Merge tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

- kprobes: Restructured stack unwinder to show properly on x86 when a
stack dump happens from a kretprobe callback.

- Fix to bootconfig parsing

- Have tracefs allow owner and group permissions by default (only
denying others). There's been pressure to allow non root to tracefs
in a controlled fashion, and using groups is probably the safest.

- Bootconfig memory managament updates.

- Bootconfig clean up to have the tools directory be less dependent on
changes in the kernel tree.

- Allow perf to be traced by function tracer.

- Rewrite of function graph tracer to be a callback from the function
tracer instead of having its own trampoline (this change will happen
on an arch by arch basis, and currently only x86_64 implements it).

- Allow multiple direct trampolines (bpf hooks to functions) be batched
together in one synchronization.

- Allow histogram triggers to add variables that can perform
calculations against the event's fields.

- Use the linker to determine architecture callbacks from the ftrace
trampoline to allow for proper parameter prototypes and prevent
warnings from the compiler.

- Extend histogram triggers to key off of variables.

- Have trace recursion use bit magic to determine preempt context over
if branches.

- Have trace recursion disable preemption as all use cases do anyway.

- Added testing for verification of tracing utilities.

- Various small clean ups and fixes.

* tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (101 commits)
tracing/histogram: Fix semicolon.cocci warnings
tracing/histogram: Fix documentation inline emphasis warning
tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together
tracing: Show size of requested perf buffer
bootconfig: Initialize ret in xbc_parse_tree()
ftrace: do CPU checking after preemption disabled
ftrace: disable preemption when recursion locked
tracing/histogram: Document expression arithmetic and constants
tracing/histogram: Optimize division by a power of 2
tracing/histogram: Covert expr to const if both operands are constants
tracing/histogram: Simplify handling of .sym-offset in expressions
tracing: Fix operator precedence for hist triggers expression
tracing: Add division and multiplication support for hist triggers
tracing: Add support for creating hist trigger variables from literal
selftests/ftrace: Stop tracing while reading the trace file by default
MAINTAINERS: Update KPROBES and TRACING entries
test_kprobes: Move it from kernel/ to lib/
docs, kprobes: Remove invalid URL and add new reference
samples/kretprobes: Fix return value if register_kretprobe() failed
lib/bootconfig: Fix the xbc_get_info kerneldoc
...

Documentation/trace/histogram.rst

···
 
   # echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ...' >> event3/trigger
 
+Expressions support the use of addition, subtraction, multiplication and
+division operators (+-\*/).
+
+Note that division by zero always returns -1.
+
+Numeric constants can also be used directly in an expression::
+
+  # echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/1000000 ...' >> event/trigger
+
+or assigned to a variable and referenced in a subsequent expression::
+
+  # echo 'hist:keys=next_pid:us_per_sec=1000000 ...' >> event/trigger
+  # echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/$us_per_sec ...' >> event/trigger
+
 2.2.2 Synthetic Events
 ----------------------
 

Documentation/trace/kprobes.rst

···
 
 For additional information on Kprobes, refer to the following URLs:
 
-- https://www.ibm.com/developerworks/library/l-kprobes/index.html
+- https://lwn.net/Articles/132196/
 - https://www.kernel.org/doc/ols/2006/ols2006v2-pages-109-124.pdf
 

Documentation/trace/timerlat-tracer.rst

···
 ###############
 
 The timerlat tracer aims to help the preemptive kernel developers to
-find souces of wakeup latencies of real-time threads. Like cyclictest,
+find sources of wakeup latencies of real-time threads. Like cyclictest,
 the tracer sets a periodic timer that wakes up a thread. The thread then
 computes a *wakeup latency* value as the difference between the *current
 time* and the *absolute time* that the timer was set to expire. The main
···
 ID field serves to relate the *irq* execution to its respective *thread*
 execution.
 
-The *irq*/*thread* splitting is important to clarify at which context
+The *irq*/*thread* splitting is important to clarify in which context
 the unexpected high value is coming from. The *irq* context can be
-delayed by hardware related actions, such as SMIs, NMIs, IRQs
-or by a thread masking interrupts. Once the timer happens, the delay
+delayed by hardware-related actions, such as SMIs, NMIs, IRQs,
+or by thread masking interrupts. Once the timer happens, the delay
 can also be influenced by blocking caused by threads. For example, by
-postponing the scheduler execution via preempt_disable(), by the
-scheduler execution, or by masking interrupts. Threads can
-also be delayed by the interference from other threads and IRQs.
+postponing the scheduler execution via preempt_disable(), scheduler
+execution, or masking interrupts. Threads can also be delayed by the
+interference from other threads and IRQs.
 
 Tracer options
 ---------------------
···
 
  - cpus: CPUs at which a timerlat thread will execute.
  - timerlat_period_us: the period of the timerlat thread.
- - osnoise/stop_tracing_us: stop the system tracing if a
+ - stop_tracing_us: stop the system tracing if a
    timer latency at the *irq* context higher than the configured
    value happens. Writing 0 disables this option.
  - stop_tracing_total_us: stop the system tracing if a
-   timer latency at the *thread* context higher than the configured
+   timer latency at the *thread* context is higher than the configured
    value happens. Writing 0 disables this option.
- - print_stack: save the stack of the IRQ ocurrence, and print
-   it afte the *thread context* event".
+ - print_stack: save the stack of the IRQ occurrence, and print
+   it after the *thread context* event".
 
 timerlat and osnoise
 ----------------------------
···
       timerlat/5-1035    [005] .......   548.771104: #402268 context thread timer_latency     39960 ns
 
 In this case, the root cause of the timer latency does not point to a
-single cause, but to multiple ones. Firstly, the timer IRQ was delayed
+single cause but to multiple ones. Firstly, the timer IRQ was delayed
 for 13 us, which may point to a long IRQ disabled section (see IRQ
 stacktrace section). Then the timer interrupt that wakes up the timerlat
 thread took 7597 ns, and the qxl:21 device IRQ took 7139 ns. Finally,

MAINTAINERS

···
 M:	"David S. Miller" <[e-mail]>
 M:	Masami Hiramatsu <[e-mail]>
 S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
 F:	Documentation/trace/kprobes.rst
 F:	include/asm-generic/kprobes.h
 F:	include/linux/kprobes.h
 F:	kernel/kprobes.c
+F:	lib/test_kprobes.c
+F:	samples/kprobes
 
 KS0108 LCD CONTROLLER DRIVER
 M:	Miguel Ojeda <[e-mail]>
···
 M:	Steven Rostedt <[e-mail]>
 M:	Ingo Molnar <[e-mail]>
 S:	Maintained
-T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf/core
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
 F:	Documentation/trace/ftrace.rst
 F:	arch/*/*/*/ftrace.h
 F:	arch/*/kernel/ftrace.c

arch/Kconfig

···
 config HAVE_KPROBES_ON_FTRACE
 	bool
 
+config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
+	bool
+	help
+	  Since kretprobes modifies return address on the stack, the
+	  stacktrace may see the kretprobe trampoline address instead
+	  of correct one. If the architecture stacktrace code and
+	  unwinder can adjust such entries, select this configuration.
+
 config HAVE_FUNCTION_ERROR_INJECTION
 	bool
 

arch/arc/include/asm/kprobes.h

···
 };
 
 int kprobe_fault_handler(struct pt_regs *regs, unsigned long cause);
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 void trap_is_kprobe(unsigned long address, struct pt_regs *regs);
 #else
 #define trap_is_kprobe(address, regs)

arch/arc/include/asm/ptrace.h

···
 	return (long)regs->r0;
 }
 
+static inline void instruction_pointer_set(struct pt_regs *regs,
+					   unsigned long val)
+{
+	instruction_pointer(regs) = val;
+}
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_PTRACE_H */

arch/arc/kernel/kprobes.c

···
 
 static void __used kretprobe_trampoline_holder(void)
 {
-	__asm__ __volatile__(".global kretprobe_trampoline\n"
-			     "kretprobe_trampoline:\n" "nop\n");
+	__asm__ __volatile__(".global __kretprobe_trampoline\n"
+			     "__kretprobe_trampoline:\n"
+			     "nop\n");
 }
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
···
 	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->blink = (unsigned long)&kretprobe_trampoline;
+	regs->blink = (unsigned long)&__kretprobe_trampoline;
 }
 
 static int __kprobes trampoline_probe_handler(struct kprobe *p,
 					      struct pt_regs *regs)
 {
-	regs->ret = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
+	regs->ret = __kretprobe_trampoline_handler(regs, NULL);
 
 	/* By returning a non zero value, we are telling the kprobe handler
 	 * that we don't want the post_handler to run
···
 }
 
 static struct kprobe trampoline_p = {
-	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
+	.addr = (kprobe_opcode_t *) &__kretprobe_trampoline,
 	.pre_handler = trampoline_probe_handler
 };
 
···
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
-	if (p->addr == (kprobe_opcode_t *) &kretprobe_trampoline)
+	if (p->addr == (kprobe_opcode_t *) &__kretprobe_trampoline)
 		return 1;
 
 	return 0;

arch/arm/Kconfig

···
 	bool
 	default y
 	select ARCH_32BIT_OFF_T
+	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE if HAVE_KRETPROBES && FRAME_POINTER && !ARM_UNWIND
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE

arch/arm/include/asm/stacktrace.h

···
 #define __ASM_STACKTRACE_H
 
 #include <asm/ptrace.h>
+#include <linux/llist.h>
 
 struct stackframe {
 	/*
···
 	unsigned long sp;
 	unsigned long lr;
 	unsigned long pc;
+#ifdef CONFIG_KRETPROBES
+	struct llist_node *kr_cur;
+	struct task_struct *tsk;
+#endif
 };
 
 static __always_inline
···
 		frame->sp = regs->ARM_sp;
 		frame->lr = regs->ARM_lr;
 		frame->pc = regs->ARM_pc;
+#ifdef CONFIG_KRETPROBES
+		frame->kr_cur = NULL;
+		frame->tsk = current;
+#endif
 }
 
 extern int unwind_frame(struct stackframe *frame);

arch/arm/kernel/ftrace.c

···
 
 	return ret;
 }
-
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER

arch/arm/kernel/return_address.c

···
 	frame.sp = current_stack_pointer;
 	frame.lr = (unsigned long)__builtin_return_address(0);
 	frame.pc = (unsigned long)return_address;
+#ifdef CONFIG_KRETPROBES
+	frame.kr_cur = NULL;
+	frame.tsk = current;
+#endif
 
 	walk_stackframe(&frame, save_return_addr, &data);
 

arch/arm/kernel/stacktrace.c

···
 // SPDX-License-Identifier: GPL-2.0-only
 #include <linux/export.h>
+#include <linux/kprobes.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/stacktrace.h>
···
 
 	frame->sp = frame->fp;
 	frame->fp = *(unsigned long *)(fp);
-	frame->pc = frame->lr;
-	frame->lr = *(unsigned long *)(fp + 4);
+	frame->pc = *(unsigned long *)(fp + 4);
 #else
 	/* check current frame pointer is within bounds */
 	if (fp < low + 12 || fp > high - 4)
···
 	frame->fp = *(unsigned long *)(fp - 12);
 	frame->sp = *(unsigned long *)(fp - 8);
 	frame->pc = *(unsigned long *)(fp - 4);
+#endif
+#ifdef CONFIG_KRETPROBES
+	if (is_kretprobe_trampoline(frame->pc))
+		frame->pc = kretprobe_find_ret_addr(frame->tsk,
+					(void *)frame->fp, &frame->kr_cur);
 #endif
 
 	return 0;
···
 		frame.lr = (unsigned long)__builtin_return_address(0);
 		frame.pc = (unsigned long)__save_stack_trace;
 	}
+#ifdef CONFIG_KRETPROBES
+	frame.kr_cur = NULL;
+	frame.tsk = tsk;
+#endif
 
 	walk_stackframe(&frame, save_trace, &data);
 }
···
 	frame.sp = regs->ARM_sp;
 	frame.lr = regs->ARM_lr;
 	frame.pc = regs->ARM_pc;
+#ifdef CONFIG_KRETPROBES
+	frame.kr_cur = NULL;
+	frame.tsk = current;
+#endif
 
 	walk_stackframe(&frame, save_trace, &data);
 }

arch/arm/probes/kprobes/core.c

···
  * Copyright (C) 2007 Marvell Ltd.
  */
 
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
 #include <linux/module.h>
···
 				break;
 			case KPROBE_REENTER:
 				/* A nested probe was hit in FIQ, it is a BUG */
-				pr_warn("Unrecoverable kprobe detected.\n");
+				pr_warn("Failed to recover from reentered kprobes.\n");
 				dump_kprobe(p);
 				fallthrough;
 			default:
···
 /*
  * When a retprobed function returns, trampoline_handler() is called,
  * calling the kretprobe's handler. We construct a struct pt_regs to
- * give a view of registers r0-r11 to the user return-handler.  This is
- * not a complete pt_regs structure, but that should be plenty sufficient
- * for kretprobe handlers which should normally be interested in r0 only
- * anyway.
+ * give a view of registers r0-r11, sp, lr, and pc to the user
+ * return-handler. This is not a complete pt_regs structure, but that
+ * should be enough for stacktrace from the return handler with or
+ * without pt_regs.
  */
-void __naked __kprobes kretprobe_trampoline(void)
+void __naked __kprobes __kretprobe_trampoline(void)
 {
 	__asm__ __volatile__ (
+#ifdef CONFIG_FRAME_POINTER
+		"ldr	lr, =__kretprobe_trampoline	\n\t"
+	/* __kretprobe_trampoline makes a framepointer on pt_regs. */
+#ifdef CONFIG_CC_IS_CLANG
+		"stmdb	sp, {sp, lr, pc}	\n\t"
+		"sub	sp, sp, #12		\n\t"
+		/* In clang case, pt_regs->ip = lr. */
+		"stmdb	sp!, {r0 - r11, lr}	\n\t"
+		/* fp points regs->r11 (fp) */
+		"add	fp, sp,	#44		\n\t"
+#else /* !CONFIG_CC_IS_CLANG */
+		/* In gcc case, pt_regs->ip = fp. */
+		"stmdb	sp, {fp, sp, lr, pc}	\n\t"
+		"sub	sp, sp, #16		\n\t"
 		"stmdb	sp!, {r0 - r11}		\n\t"
+		/* fp points regs->r15 (pc) */
+		"add	fp, sp, #60		\n\t"
+#endif /* CONFIG_CC_IS_CLANG */
+#else /* !CONFIG_FRAME_POINTER */
+		"sub	sp, sp, #16		\n\t"
+		"stmdb	sp!, {r0 - r11}		\n\t"
+#endif /* CONFIG_FRAME_POINTER */
 		"mov	r0, sp			\n\t"
 		"bl	trampoline_handler	\n\t"
 		"mov	lr, r0			\n\t"
 		"ldmia	sp!, {r0 - r11}		\n\t"
+		"add	sp, sp, #16		\n\t"
 #ifdef CONFIG_THUMB2_KERNEL
 		"bx	lr			\n\t"
 #else
···
 		: : : "memory");
 }
 
-/* Called from kretprobe_trampoline */
+/* Called from __kretprobe_trampoline */
 static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
 {
-	return (void *)kretprobe_trampoline_handler(regs, &kretprobe_trampoline,
-						    (void *)regs->ARM_fp);
+	return (void *)kretprobe_trampoline_handler(regs, (void *)regs->ARM_fp);
 }
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
···
 	ri->fp = (void *)regs->ARM_fp;
 
 	/* Replace the return addr with trampoline addr. */
-	regs->ARM_lr = (unsigned long)&kretprobe_trampoline;
+	regs->ARM_lr = (unsigned long)&__kretprobe_trampoline;
 }
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)

arch/arm/probes/kprobes/opt-arm.c

···
 }
 
 int arch_within_optimized_kprobe(struct optimized_kprobe *op,
-				unsigned long addr)
+				 kprobe_opcode_t *addr)
 {
-	return ((unsigned long)op->kp.addr <= addr &&
-		(unsigned long)op->kp.addr + RELATIVEJUMP_SIZE > addr);
+	return (op->kp.addr <= addr &&
+		op->kp.addr + (RELATIVEJUMP_SIZE / sizeof(kprobe_opcode_t)) > addr);
+
 }
 
 void arch_remove_optimized_kprobe(struct optimized_kprobe *op)

arch/arm64/Kconfig

···
 	select ACPI_PPTT if ACPI
 	select ARCH_HAS_DEBUG_WX
 	select ARCH_BINFMT_ELF_STATE
+	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
 	select ARCH_ENABLE_MEMORY_HOTPLUG
 	select ARCH_ENABLE_MEMORY_HOTREMOVE

arch/arm64/include/asm/kprobes.h

···
 int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
 int kprobe_exceptions_notify(struct notifier_block *self,
 			     unsigned long val, void *data);
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 void __kprobes *trampoline_probe_handler(struct pt_regs *regs);
 
 #endif /* CONFIG_KPROBES */

arch/arm64/include/asm/stacktrace.h

···
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 #include <linux/types.h>
+#include <linux/llist.h>
 
 #include <asm/memory.h>
 #include <asm/ptrace.h>
···
 	enum stack_type prev_type;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	int graph;
+#endif
+#ifdef CONFIG_KRETPROBES
+	struct llist_node *kr_cur;
 #endif
 };
 

arch/arm64/kernel/ftrace.c

···
 	command |= FTRACE_MAY_SLEEP;
 	ftrace_modify_all_code(command);
 }
-
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER

arch/arm64/kernel/probes/kprobes.c

···
  * Copyright (C) 2013 Linaro Limited.
  * Author: Sandeepa Prabhu <[e-mail]>
  */
+
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/extable.h>
 #include <linux/kasan.h>
 #include <linux/kernel.h>
···
 		break;
 	case KPROBE_HIT_SS:
 	case KPROBE_REENTER:
-		pr_warn("Unrecoverable kprobe detected.\n");
+		pr_warn("Failed to recover from reentered kprobes.\n");
 		dump_kprobe(p);
 		BUG();
 		break;
···
 
 void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
 {
-	return (void *)kretprobe_trampoline_handler(regs, &kretprobe_trampoline,
-					(void *)kernel_stack_pointer(regs));
+	return (void *)kretprobe_trampoline_handler(regs, (void *)regs->regs[29]);
 }
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 				      struct pt_regs *regs)
 {
 	ri->ret_addr = (kprobe_opcode_t *)regs->regs[30];
-	ri->fp = (void *)kernel_stack_pointer(regs);
+	ri->fp = (void *)regs->regs[29];
 
 	/* replace return addr (x30) with trampoline */
-	regs->regs[30] = (long)&kretprobe_trampoline;
+	regs->regs[30] = (long)&__kretprobe_trampoline;
 }
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)

arch/arm64/kernel/probes/kprobes_trampoline.S

···
 	ldp x28, x29, [sp, #S_X28]
 	.endm
 
-SYM_CODE_START(kretprobe_trampoline)
+SYM_CODE_START(__kretprobe_trampoline)
 	sub sp, sp, #PT_REGS_SIZE
 
 	save_all_base_regs
+
+	/* Setup a frame pointer. */
+	add x29, sp, #S_FP
 
 	mov x0, sp
 	bl trampoline_probe_handler
···
 	 */
 	mov lr, x0
 
+	/* The frame pointer (x29) is restored with other registers. */
 	restore_all_base_regs
 
 	add sp, sp, #PT_REGS_SIZE
 	ret
 
-SYM_CODE_END(kretprobe_trampoline)
+SYM_CODE_END(__kretprobe_trampoline)

arch/arm64/kernel/stacktrace.c

···
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	frame->graph = 0;
 #endif
+#ifdef CONFIG_KRETPROBES
+	frame->kr_cur = NULL;
+#endif
 
 	/*
 	 * Prime the first unwind.
···
 		frame->pc = ret_stack->ret;
 	}
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+#ifdef CONFIG_KRETPROBES
+	if (is_kretprobe_trampoline(frame->pc))
+		frame->pc = kretprobe_find_ret_addr(tsk, (void *)frame->fp, &frame->kr_cur);
+#endif
 
 	frame->pc = ptrauth_strip_insn_pac(frame->pc);
 

arch/csky/include/asm/kprobes.h

···
 int kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr);
 int kprobe_breakpoint_handler(struct pt_regs *regs);
 int kprobe_single_step_handler(struct pt_regs *regs);
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 void __kprobes *trampoline_probe_handler(struct pt_regs *regs);
 
 #endif /* CONFIG_KPROBES */

arch/csky/kernel/ftrace.c

···
 				(unsigned long)func, true, true);
 	return ret;
 }
-
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS

arch/csky/kernel/probes/ftrace.c

···
 
 #include <linux/kprobes.h>
 
-int arch_check_ftrace_location(struct kprobe *p)
-{
-	if (ftrace_location((unsigned long)p->addr))
-		p->flags |= KPROBE_FLAG_FTRACE;
-	return 0;
-}
-
 /* Ftrace callback handler for kprobes -- called under preepmt disabled */
 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
···
 		return;
 
 	regs = ftrace_get_regs(fregs);
-	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (!p) {
 		p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE));
···
 		__this_cpu_write(current_kprobe, NULL);
 	}
 out:
-	preempt_enable_notrace();
 	ftrace_test_recursion_unlock(bit);
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/csky/kernel/probes/kprobes.c

···
 // SPDX-License-Identifier: GPL-2.0+
 
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/kprobes.h>
 #include <linux/extable.h>
 #include <linux/slab.h>
···
 {
 	unsigned long probe_addr = (unsigned long)p->addr;
 
-	if (probe_addr & 0x1) {
-		pr_warn("Address not aligned.\n");
-		return -EINVAL;
-	}
+	if (probe_addr & 0x1)
+		return -EILSEQ;
 
 	/* copy instruction */
 	p->opcode = le32_to_cpu(*p->addr);
···
 		break;
 	case KPROBE_HIT_SS:
 	case KPROBE_REENTER:
-		pr_warn("Unrecoverable kprobe detected.\n");
+		pr_warn("Failed to recover from reentered kprobes.\n");
 		dump_kprobe(p);
 		BUG();
 		break;
···
 
 void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
 {
-	return (void *)kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
+	return (void *)kretprobe_trampoline_handler(regs, NULL);
 }
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
···
 {
 	ri->ret_addr = (kprobe_opcode_t *)regs->lr;
 	ri->fp = NULL;
-	regs->lr = (unsigned long) &kretprobe_trampoline;
+	regs->lr = (unsigned long) &__kretprobe_trampoline;
 }
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)

arch/csky/kernel/probes/kprobes_trampoline.S

···
 
 #include <abi/entry.h>
 
-ENTRY(kretprobe_trampoline)
+ENTRY(__kretprobe_trampoline)
 	SAVE_REGS_FTRACE
 
 	mov	a0, sp /* pt_regs */
···
 
 	RESTORE_REGS_FTRACE
 	rts
-ENDPROC(kretprobe_trampoline)
+ENDPROC(__kretprobe_trampoline)

arch/ia64/include/asm/ptrace.h

···
  * the canonical representation by adding to instruction pointer.
  */
 # define instruction_pointer(regs) ((regs)->cr_iip + ia64_psr(regs)->ri)
+# define instruction_pointer_set(regs, val)	\
+({						\
+	ia64_psr(regs)->ri = (val & 0xf);	\
+	regs->cr_iip = (val & ~0xfULL);		\
+})
 
 static inline unsigned long user_stack_pointer(struct pt_regs *regs)
 {

arch/ia64/kernel/ftrace.c

···
 	flush_icache_range(addr, addr + 16);
 	return 0;
 }
-
-/* run from kstop_machine */
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}

arch/ia64/kernel/kprobes.c

···
 	__this_cpu_write(current_kprobe, p);
 }
 
-static void kretprobe_trampoline(void)
+void __kretprobe_trampoline(void)
 {
 }
 
 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 {
-	regs->cr_iip = __kretprobe_trampoline_handler(regs, kretprobe_trampoline, NULL);
+	regs->cr_iip = __kretprobe_trampoline_handler(regs, NULL);
 	/*
 	 * By returning a non-zero value, we are telling
 	 * kprobe_handler() that we don't want the post_handler
···
 	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
+	regs->b0 = (unsigned long)dereference_function_descriptor(__kretprobe_trampoline);
 }
 
 /* Check the instruction in the slot is break */
···
 	return ret;
 }
 
-unsigned long arch_deref_entry_point(void *entry)
-{
-	return ((struct fnptr *)entry)->ip;
-}
-
 static struct kprobe trampoline_p = {
 	.pre_handler = trampoline_probe_handler
 };
···
 int __init arch_init_kprobes(void)
 {
 	trampoline_p.addr =
-		(kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
+		dereference_function_descriptor(__kretprobe_trampoline);
 	return register_kprobe(&trampoline_p);
 }
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
 	if (p->addr ==
-		(kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip)
+		dereference_function_descriptor(__kretprobe_trampoline))
 		return 1;
 
 	return 0;

arch/microblaze/kernel/ftrace.c

···
 	return ret;
 }
 
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
-
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
 	unsigned long ip = (unsigned long)(&ftrace_call);

arch/mips/kernel/kprobes.c

···
  *   Copyright (C) IBM Corporation, 2002, 2004
  */
 
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/kprobes.h>
 #include <linux/preempt.h>
 #include <linux/uaccess.h>
···
 	insn = p->addr[0];
 
 	if (insn_has_ll_or_sc(insn)) {
-		pr_notice("Kprobes for ll and sc instructions are not"
-			  "supported\n");
+		pr_notice("Kprobes for ll and sc instructions are not supported\n");
 		ret = -EINVAL;
 		goto out;
 	}
···
 	return 0;
 
 unaligned:
-	pr_notice("%s: unaligned epc - sending SIGBUS.\n", current->comm);
+	pr_notice("Failed to emulate branch instruction because of unaligned epc - sending SIGBUS to %s.\n", current->comm);
 	force_sig(SIGBUS);
 	return -EFAULT;
 
···
 		regs->cp0_epc = (unsigned long)p->addr;
 	else if (insn_has_delayslot(p->opcode)) {
 		ret = evaluate_branch_instruction(p, regs, kcb);
-		if (ret < 0) {
-			pr_notice("Kprobes: Error in evaluating branch\n");
+		if (ret < 0)
 			return;
-		}
 	}
 	regs->cp0_epc = (unsigned long)&p->ainsn.insn[0];
 }
···
 		/* Keep the assembler from reordering and placing JR here. */
 		".set noreorder\n\t"
 		"nop\n\t"
-		".global kretprobe_trampoline\n"
-		"kretprobe_trampoline:\n\t"
+		".global __kretprobe_trampoline\n"
+		"__kretprobe_trampoline:\n\t"
 		"nop\n\t"
 		".set pop"
 		: : : "memory");
 }
 
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 				      struct pt_regs *regs)
···
 	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->regs[31] = (unsigned long)kretprobe_trampoline;
+	regs->regs[31] = (unsigned long)__kretprobe_trampoline;
 }
 
 /*
···
 static int __kprobes trampoline_probe_handler(struct kprobe *p,
 						struct pt_regs *regs)
 {
-	instruction_pointer(regs) = __kretprobe_trampoline_handler(regs,
-						kretprobe_trampoline, NULL);
+	instruction_pointer(regs) = __kretprobe_trampoline_handler(regs, NULL);
 	/*
 	 * By returning a non-zero value, we are telling
 	 * kprobe_handler() that we don't want the post_handler
···
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
-	if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
+	if (p->addr == (kprobe_opcode_t *)__kretprobe_trampoline)
 		return 1;
 
 	return 0;
 }
 
 static struct kprobe trampoline_p = {
-	.addr = (kprobe_opcode_t *)kretprobe_trampoline,
+	.addr = (kprobe_opcode_t *)__kretprobe_trampoline,
 	.pre_handler = trampoline_probe_handler
 };
 

arch/nds32/kernel/ftrace.c

···
 	/* restore all state needed by the compiler epilogue */
 }
 
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
-
 static unsigned long gen_sethi_insn(unsigned long addr)
 {
 	unsigned long opcode = 0x46000000;

arch/parisc/kernel/ftrace.c

···
 #endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
-
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
 	ftrace_func = func;
···
 		return;
 
 	regs = ftrace_get_regs(fregs);
-	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (unlikely(!p) || kprobe_disabled(p))
 		goto out;
···
 	}
 	__this_cpu_write(current_kprobe, NULL);
 out:
-	preempt_enable_notrace();
 	ftrace_test_recursion_unlock(bit);
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/parisc/kernel/kprobes.c

···
 	return 1;
 }
 
-static inline void kretprobe_trampoline(void)
+void __kretprobe_trampoline(void)
 {
 	asm volatile("nop");
 	asm volatile("nop");
···
 {
 	unsigned long orig_ret_address;
 
-	orig_ret_address = __kretprobe_trampoline_handler(regs, trampoline_p.addr, NULL);
+	orig_ret_address = __kretprobe_trampoline_handler(regs, NULL);
 	instruction_pointer_set(regs, orig_ret_address);
 
 	return 1;
···
 int __init arch_init_kprobes(void)
 {
 	trampoline_p.addr = (kprobe_opcode_t *)
-		dereference_function_descriptor(kretprobe_trampoline);
+		dereference_function_descriptor(__kretprobe_trampoline);
 	return register_kprobe(&trampoline_p);
 }

arch/powerpc/include/asm/kprobes.h

···
 #define flush_insn_slot(p)	do { } while (0)
 #define kretprobe_blacklist_size 0
 
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 extern void arch_remove_kprobe(struct kprobe *p);
 
 /* Architecture specific copy of original instruction */

arch/powerpc/kernel/kprobes-ftrace.c

···
 		return;
 
 	regs = ftrace_get_regs(fregs);
-	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)nip);
 	if (unlikely(!p) || kprobe_disabled(p))
 		goto out;
···
 		__this_cpu_write(current_kprobe, NULL);
 	}
 out:
-	preempt_enable_notrace();
 	ftrace_test_recursion_unlock(bit);
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/powerpc/kernel/kprobes.c

···
 	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->link = (unsigned long)kretprobe_trampoline;
+	regs->link = (unsigned long)__kretprobe_trampoline;
 }
 NOKPROBE_SYMBOL(arch_prepare_kretprobe);
 
···
  * 	- When the probed function returns, this probe
  * 		causes the handlers to fire
  */
-asm(".global kretprobe_trampoline\n"
-	".type kretprobe_trampoline, @function\n"
-	"kretprobe_trampoline:\n"
+asm(".global __kretprobe_trampoline\n"
+	".type __kretprobe_trampoline, @function\n"
+	"__kretprobe_trampoline:\n"
 	"nop\n"
 	"blr\n"
-	".size kretprobe_trampoline, .-kretprobe_trampoline\n");
+	".size __kretprobe_trampoline, .-__kretprobe_trampoline\n");
 
 /*
  * Called when the probe at kretprobe trampoline is hit
···
 {
 	unsigned long orig_ret_address;
 
-	orig_ret_address = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
+	orig_ret_address = __kretprobe_trampoline_handler(regs, NULL);
 	/*
 	 * We get here through one of two paths:
 	 * 1. by taking a trap -> kprobe_handler() -> here
···
 	 * as it is used to determine the return address from the trap.
 	 * For (2), since nip is not honoured with optprobes, we instead setup
 	 * the link register properly so that the subsequent 'blr' in
-	 * kretprobe_trampoline jumps back to the right instruction.
+	 * __kretprobe_trampoline jumps back to the right instruction.
 	 *
 	 * For nip, we should set the address to the previous instruction since
 	 * we end up emulating it in kprobe_handler(), which increments the nip
···
 }
 NOKPROBE_SYMBOL(kprobe_fault_handler);
 
-unsigned long arch_deref_entry_point(void *entry)
-{
-#ifdef PPC64_ELF_ABI_v1
-	if (!kernel_text_address((unsigned long)entry))
-		return ppc_global_function_entry(entry);
-	else
-#endif
-		return (unsigned long)entry;
-}
-NOKPROBE_SYMBOL(arch_deref_entry_point);
-
 static struct kprobe trampoline_p = {
-	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
+	.addr = (kprobe_opcode_t *) &__kretprobe_trampoline,
 	.pre_handler = trampoline_probe_handler
 };
 
···
 
 int arch_trampoline_kprobe(struct kprobe *p)
 {
-	if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
+	if (p->addr == (kprobe_opcode_t *)&__kretprobe_trampoline)
 		return 1;
 
 	return 0;

arch/powerpc/kernel/optprobes.c

···
 	 * has a 'nop' instruction, which can be emulated.
 	 * So further checks can be skipped.
 	 */
-	if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
+	if (p->addr == (kprobe_opcode_t *)&__kretprobe_trampoline)
 		return addr + sizeof(kprobe_opcode_t);
 
 	/*
···
 	}
 }
 
-int arch_within_optimized_kprobe(struct optimized_kprobe *op, unsigned long addr)
+int arch_within_optimized_kprobe(struct optimized_kprobe *op, kprobe_opcode_t *addr)
 {
-	return ((unsigned long)op->kp.addr <= addr &&
-		(unsigned long)op->kp.addr + RELATIVEJUMP_SIZE > addr);
+	return (op->kp.addr <= addr &&
+		op->kp.addr + (RELATIVEJUMP_SIZE / sizeof(kprobe_opcode_t)) > addr);
 }

arch/powerpc/kernel/stacktrace.c

···
 		 * Mark stacktraces with kretprobed functions on them
 		 * as unreliable.
 		 */
-		if (ip == (unsigned long)kretprobe_trampoline)
+		if (ip == (unsigned long)__kretprobe_trampoline)
 			return -EINVAL;
 #endif
 

arch/riscv/include/asm/kprobes.h

···
 int kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr);
 bool kprobe_breakpoint_handler(struct pt_regs *regs);
 bool kprobe_single_step_handler(struct pt_regs *regs);
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 void __kprobes *trampoline_probe_handler(struct pt_regs *regs);
 
 #endif /* CONFIG_KPROBES */

arch/riscv/kernel/ftrace.c

···
 
 	return ret;
 }
-
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
 #endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS

arch/riscv/kernel/probes/ftrace.c

···
 	if (bit < 0)
 		return;
 
-	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (unlikely(!p) || kprobe_disabled(p))
 		goto out;
···
 		__this_cpu_write(current_kprobe, NULL);
 	}
 out:
-	preempt_enable_notrace();
 	ftrace_test_recursion_unlock(bit);
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/riscv/kernel/probes/kprobes.c

···
 // SPDX-License-Identifier: GPL-2.0+
 
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/kprobes.h>
 #include <linux/extable.h>
 #include <linux/slab.h>
···
 {
 	unsigned long probe_addr = (unsigned long)p->addr;
 
-	if (probe_addr & 0x1) {
-		pr_warn("Address not aligned.\n");
-
-		return -EINVAL;
-	}
+	if (probe_addr & 0x1)
+		return -EILSEQ;
 
 	/* copy instruction */
 	p->opcode = *p->addr;
···
 		break;
 	case KPROBE_HIT_SS:
 	case KPROBE_REENTER:
-		pr_warn("Unrecoverable kprobe detected.\n");
+		pr_warn("Failed to recover from reentered kprobes.\n");
 		dump_kprobe(p);
 		BUG();
 		break;
···
 
 void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
 {
-	return (void *)kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
+	return (void *)kretprobe_trampoline_handler(regs, NULL);
 }
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
···
 {
 	ri->ret_addr = (kprobe_opcode_t *)regs->ra;
 	ri->fp = NULL;
-	regs->ra = (unsigned long) &kretprobe_trampoline;
+	regs->ra = (unsigned long) &__kretprobe_trampoline;
 }
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)

arch/riscv/kernel/probes/kprobes_trampoline.S

···
 	REG_L x31, PT_T6(sp)
 	.endm
 
-ENTRY(kretprobe_trampoline)
+ENTRY(__kretprobe_trampoline)
 	addi sp, sp, -(PT_SIZE_ON_STACK)
 	save_all_base_regs
 
···
 	addi sp, sp, PT_SIZE_ON_STACK
 
 	ret
-ENDPROC(kretprobe_trampoline)
+ENDPROC(__kretprobe_trampoline)

arch/s390/include/asm/kprobes.h

···
 };
 
 void arch_remove_kprobe(struct kprobe *p);
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 
 int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
 int kprobe_exceptions_notify(struct notifier_block *self,

arch/s390/kernel/ftrace.c

···
 	return 0;
 }
 
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
-
 void arch_ftrace_update_code(int command)
 {
 	if (ftrace_shared_hotpatch_trampoline(NULL))

arch/s390/kernel/kprobes.c

···
  * s390 port, used ppc64 as template. Mike Grundy <[e-mail]>
  */
 
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/moduleloader.h>
 #include <linux/kprobes.h>
 #include <linux/ptrace.h>
···
 	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->gprs[14] = (unsigned long) &kretprobe_trampoline;
+	regs->gprs[14] = (unsigned long) &__kretprobe_trampoline;
 }
 NOKPROBE_SYMBOL(arch_prepare_kretprobe);
 
···
 		 * is a BUG. The code path resides in the .kprobes.text
 		 * section and is executed with interrupts disabled.
 		 */
-		pr_err("Invalid kprobe detected.\n");
+		pr_err("Failed to recover from reentered kprobes.\n");
 		dump_kprobe(p);
 		BUG();
 	}
···
  */
 static void __used kretprobe_trampoline_holder(void)
 {
-	asm volatile(".global kretprobe_trampoline\n"
-		     "kretprobe_trampoline: bcr 0,0\n");
+	asm volatile(".global __kretprobe_trampoline\n"
+		     "__kretprobe_trampoline: bcr 0,0\n");
 }
 
 /*
···
  */
 static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 {
-	regs->psw.addr = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
+	regs->psw.addr = __kretprobe_trampoline_handler(regs, NULL);
 	/*
 	 * By returning a non-zero value, we are telling
 	 * kprobe_handler() that we don't want the post_handler
···
 NOKPROBE_SYMBOL(kprobe_exceptions_notify);
 
 static struct kprobe trampoline = {
-	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
+	.addr = (kprobe_opcode_t *) &__kretprobe_trampoline,
 	.pre_handler = trampoline_probe_handler
 };
 
···
 
 int arch_trampoline_kprobe(struct kprobe *p)
 {
-	return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline;
+	return p->addr == (kprobe_opcode_t *) &__kretprobe_trampoline;
 }
 NOKPROBE_SYMBOL(arch_trampoline_kprobe);

arch/s390/kernel/stacktrace.c

···
 		 * Mark stacktraces with kretprobed functions on them
 		 * as unreliable.
 		 */
-		if (state.ip == (unsigned long)kretprobe_trampoline)
+		if (state.ip == (unsigned long)__kretprobe_trampoline)
 			return -EINVAL;
 #endif
 

arch/sh/boot/compressed/misc.c

···
 void ftrace_stub(void)
 {
 }
+void arch_ftrace_ops_list_func(void)
+{
+}
 
 #define stackalign	4
 

arch/sh/include/asm/kprobes.h

···
 struct kprobe;
 
 void arch_remove_kprobe(struct kprobe *);
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 
 /* Architecture specific copy of original instruction*/
 struct arch_specific_insn {

arch/sh/kernel/ftrace.c

···
 
 	return ftrace_modify_code(rec->ip, old, new);
 }
-
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER

arch/sh/kernel/kprobes.c

···
 	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->pr = (unsigned long)kretprobe_trampoline;
+	regs->pr = (unsigned long)__kretprobe_trampoline;
 }
 
 static int __kprobes kprobe_handler(struct pt_regs *regs)
···
  */
 static void __used kretprobe_trampoline_holder(void)
 {
-	asm volatile (".globl kretprobe_trampoline\n"
-		      "kretprobe_trampoline:\n\t"
+	asm volatile (".globl __kretprobe_trampoline\n"
+		      "__kretprobe_trampoline:\n\t"
 		      "nop\n");
 }
 
 /*
- * Called when we hit the probe point at kretprobe_trampoline
+ * Called when we hit the probe point at __kretprobe_trampoline
  */
 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 {
-	regs->pc = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
+	regs->pc = __kretprobe_trampoline_handler(regs, NULL);
 
 	return 1;
 }
···
 }
 
 static struct kprobe trampoline_p = {
-	.addr = (kprobe_opcode_t *)&kretprobe_trampoline,
+	.addr = (kprobe_opcode_t *)&__kretprobe_trampoline,
 	.pre_handler = trampoline_probe_handler
 };
 

arch/sparc/include/asm/kprobes.h

···
 	flushi(&(p)->ainsn.insn[1]);	\
 } while (0)
 
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 
 /* Architecture specific copy of original instruction*/
 struct arch_specific_insn {

arch/sparc/kernel/ftrace.c

···
 	new = ftrace_call_replace(ip, (unsigned long)func);
 	return ftrace_modify_code(ip, old, new);
 }
-
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
 #endif
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER

arch/sparc/kernel/kprobes.c

···
 
 	/* Replace the return addr with trampoline addr */
 	regs->u_regs[UREG_RETPC] =
-		((unsigned long)kretprobe_trampoline) - 8;
+		((unsigned long)__kretprobe_trampoline) - 8;
 }
 
 /*
···
 {
 	unsigned long orig_ret_address = 0;
 
-	orig_ret_address = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
+	orig_ret_address = __kretprobe_trampoline_handler(regs, NULL);
 	regs->tpc = orig_ret_address;
 	regs->tnpc = orig_ret_address + 4;
 
···
 
 static void __used kretprobe_trampoline_holder(void)
 {
-	asm volatile(".global kretprobe_trampoline\n"
-		     "kretprobe_trampoline:\n"
+	asm volatile(".global __kretprobe_trampoline\n"
+		     "__kretprobe_trampoline:\n"
 		     "\tnop\n"
 		     "\tnop\n");
 }
 static struct kprobe trampoline_p = {
-	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
+	.addr = (kprobe_opcode_t *) &__kretprobe_trampoline,
 	.pre_handler = trampoline_probe_handler
 };
 
···
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
-	if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
+	if (p->addr == (kprobe_opcode_t *)&__kretprobe_trampoline)
 		return 1;
 
 	return 0;

arch/x86/Kconfig

···
 	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
 	select ARCH_32BIT_OFF_T			if X86_32
 	select ARCH_CLOCKSOURCE_INIT
+	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
 	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 || (X86_32 && HIGHMEM)
 	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
···
 	select HAVE_FAST_GUP
 	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
-	select HAVE_FUNCTION_GRAPH_TRACER
+	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
 	select HAVE_FUNCTION_TRACER
 	select HAVE_GCC_PLUGINS
 	select HAVE_HW_BREAKPOINT

arch/x86/include/asm/ftrace.h

···
 
 #define ftrace_instruction_pointer_set(fregs, _ip)	\
 	do { (fregs)->regs.ip = (_ip); } while (0)
+
+struct ftrace_ops;
+#define ftrace_graph_func ftrace_graph_func
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs);
+#else
+#define FTRACE_GRAPH_TRAMP_ADDR FTRACE_GRAPH_ADDR
 #endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE
···
 struct dyn_arch_ftrace {
 	/* No extra data needed for x86 */
 };
-
-#define FTRACE_GRAPH_TRAMP_ADDR FTRACE_GRAPH_ADDR
 
 #endif /*  CONFIG_DYNAMIC_FTRACE */
 #endif /* __ASSEMBLY__ */

arch/x86/include/asm/kprobes.h

···
 extern const int kretprobe_blacklist_size;
 
 void arch_remove_kprobe(struct kprobe *p);
-asmlinkage void kretprobe_trampoline(void);
 
 extern void arch_kprobe_override_function(struct pt_regs *regs);
 

arch/x86/include/asm/unwind.h

···
 
 #include <linux/sched.h>
 #include <linux/ftrace.h>
+#include <linux/kprobes.h>
 #include <asm/ptrace.h>
 #include <asm/stacktrace.h>
 
···
 	unsigned long stack_mask;
 	struct task_struct *task;
 	int graph_idx;
+#ifdef CONFIG_KRETPROBES
+	struct llist_node *kr_cur;
+#endif
 	bool error;
 #if defined(CONFIG_UNWINDER_ORC)
 	bool signal, full_regs;
···
 void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
 			void *orc, size_t orc_size) {}
 #endif
+
+static inline
+unsigned long unwind_recover_kretprobe(struct unwind_state *state,
+				       unsigned long addr, unsigned long *addr_p)
+{
+#ifdef CONFIG_KRETPROBES
+	return is_kretprobe_trampoline(addr) ?
+		kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) :
+		addr;
+#else
+	return addr;
+#endif
+}
+
+/* Recover the return address modified by kretprobe and ftrace_graph. */
+static inline
+unsigned long unwind_recover_ret_addr(struct unwind_state *state,
+				     unsigned long addr, unsigned long *addr_p)
+{
+	unsigned long ret;
+
+	ret = ftrace_graph_ret_addr(state->task, &state->graph_idx,
+				    addr, addr_p);
+	return unwind_recover_kretprobe(state, ret, addr_p);
+}
 
 /*
  * This disables KASAN checking when reading a value from another task's stack,

arch/x86/include/asm/unwind_hints.h

···
 	UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=8 type=UNWIND_HINT_TYPE_FUNC
 .endm
 
+#else
+
+#define UNWIND_HINT_FUNC \
+	UNWIND_HINT(ORC_REG_SP, 8, UNWIND_HINT_TYPE_FUNC, 0)
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_X86_UNWIND_HINTS_H */

arch/x86/kernel/ftrace.c

···
 	ftrace_modify_all_code(command);
 }
 
-int __init ftrace_dyn_arch_init(void)
-{
-	return 0;
-}
-
 /* Currently only x86_64 supports dynamic trampolines */
 #ifdef CONFIG_X86_64
 
···
 	return ptr + CALL_INSN_SIZE + call.disp;
 }
 
-void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
+void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
 			   unsigned long frame_pointer);
 
 /*
···
 	void *ptr;
 
 	if (ops && ops->trampoline) {
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) && \
+	defined(CONFIG_FUNCTION_GRAPH_TRACER)
 		/*
 		 * We only know about function graph tracer setting as static
 		 * trampoline.
···
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-extern void ftrace_graph_call(void);
 
+#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+extern void ftrace_graph_call(void);
 static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
 {
 	return text_gen_insn(JMP32_INSN_OPCODE, (void *)ip, (void *)addr);
···
 
 	return ftrace_mod_jmp(ip, &ftrace_stub);
 }
+#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
+int ftrace_enable_ftrace_graph_caller(void)
+{
+	return 0;
+}
 
+int ftrace_disable_ftrace_graph_caller(void)
+{
+	return 0;
+}
+#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
 #endif /* !CONFIG_DYNAMIC_FTRACE */
 
 /*
  * Hook the return address and push it in the stack of return addrs
  * in current thread info.
  */
-void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
+void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
 			   unsigned long frame_pointer)
 {
 	unsigned long return_hooker = (unsigned long)&return_to_handler;
-	unsigned long old;
-	int faulted;
+	int bit;
 
 	/*
 	 * When resuming from suspend-to-ram, this function can be indirectly
···
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;
 
-	/*
-	 * Protect against fault, even if it shouldn't
-	 * happen. This tool is too much intrusive to
-	 * ignore such a protection.
-	 */
-	asm volatile(
-		"1: " _ASM_MOV " (%[parent]), %[old]\n"
-		"2: " _ASM_MOV " %[return_hooker], (%[parent])\n"
-		"   movl $0, %[faulted]\n"
-		"3:\n"
-
-		".section .fixup, \"ax\"\n"
-		"4: movl $1, %[faulted]\n"
-		"   jmp 3b\n"
-		".previous\n"
-
-		_ASM_EXTABLE(1b, 4b)
-		_ASM_EXTABLE(2b, 4b)
-
-		: [old] "=&r" (old), [faulted] "=r" (faulted)
-		: [parent] "r" (parent), [return_hooker] "r" (return_hooker)
-		: "memory"
-	);
-
-	if (unlikely(faulted)) {
-		ftrace_graph_stop();
-		WARN_ON(1);
+	bit = ftrace_test_recursion_trylock(ip, *parent);
+	if (bit < 0)
 		return;
-	}
 
-	if (function_graph_enter(old, self_addr, frame_pointer, parent))
-		*parent = old;
+	if (!function_graph_enter(*parent, ip, frame_pointer, parent))
+		*parent = return_hooker;
+
+	ftrace_test_recursion_unlock(bit);
 }
+
+#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+	struct pt_regs *regs = &fregs->regs;
+	unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs);
+
+	prepare_ftrace_return(ip, (unsigned long *)stack, 0);
+}
+#endif
+
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */

arch/x86/kernel/ftrace_64.S

···
 SYM_FUNC_END(ftrace_caller);
 
 SYM_FUNC_START(ftrace_epilogue)
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL)
-	jmp ftrace_stub
-#endif
-
 /*
  * This is weak to keep gas from relaxing the jumps.
  * It is also used to copy the retq for trampolines.
···
 	 * If ORIG_RAX is anything but zero, make this a call to that.
 	 * See arch_ftrace_set_direct_caller().
 	 */
-	movq ORIG_RAX(%rsp), %rax
 	testq	%rax, %rax
 SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL)
 	jnz	1f
···
 	cmpq $ftrace_stub, ftrace_trace_function
 	jnz trace
 
-fgraph_trace:
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	cmpq $ftrace_stub, ftrace_graph_return
-	jnz ftrace_graph_caller
-
-	cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
-	jnz ftrace_graph_caller
-#endif
-
 SYM_INNER_LABEL(ftrace_stub, SYM_L_GLOBAL)
 	retq
 
···
 	CALL_NOSPEC r8
 	restore_mcount_regs
 
-	jmp fgraph_trace
+	jmp ftrace_stub
 SYM_FUNC_END(__fentry__)
 EXPORT_SYMBOL(__fentry__)
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
-SYM_FUNC_START(ftrace_graph_caller)
-	/* Saves rbp into %rdx and fills first parameter  */
-	save_mcount_regs
-
-	leaq MCOUNT_REG_SIZE+8(%rsp), %rsi
-	movq $0, %rdx	/* No framepointers needed */
-	call	prepare_ftrace_return
-
-	restore_mcount_regs
-
-	retq
-SYM_FUNC_END(ftrace_graph_caller)
-
 SYM_FUNC_START(return_to_handler)
 	subq  $24, %rsp
 

arch/x86/kernel/kprobes/core.c

···
 	ri->fp = sara;
 
 	/* Replace the return addr with trampoline addr */
-	*sara = (unsigned long) &kretprobe_trampoline;
+	*sara = (unsigned long) &__kretprobe_trampoline;
 }
 NOKPROBE_SYMBOL(arch_prepare_kretprobe);
 
···
  */
 asm(
 	".text\n"
-	".global kretprobe_trampoline\n"
-	".type kretprobe_trampoline, @function\n"
-	"kretprobe_trampoline:\n"
-	/* We don't bother saving the ss register */
+	".global __kretprobe_trampoline\n"
+	".type __kretprobe_trampoline, @function\n"
+	"__kretprobe_trampoline:\n"
 #ifdef CONFIG_X86_64
+	/* Push a fake return address to tell the unwinder it's a kretprobe. */
+	"	pushq $__kretprobe_trampoline\n"
+	UNWIND_HINT_FUNC
+	/* Save the 'sp - 8', this will be fixed later. */
 	"	pushq %rsp\n"
 	"	pushfq\n"
 	SAVE_REGS_STRING
 	"	movq %rsp, %rdi\n"
 	"	call trampoline_handler\n"
-	/* Replace saved sp with true return address. */
-	"	movq %rax, 19*8(%rsp)\n"
 	RESTORE_REGS_STRING
+	/* In trampoline_handler(), 'regs->flags' is copied to 'regs->sp'. */
+	"	addq $8, %rsp\n"
 	"	popfq\n"
 #else
+	/* Push a fake return address to tell the unwinder it's a kretprobe. */
+	"	pushl $__kretprobe_trampoline\n"
+	UNWIND_HINT_FUNC
+	/* Save the 'sp - 4', this will be fixed later. */
 	"	pushl %esp\n"
 	"	pushfl\n"
 	SAVE_REGS_STRING
 	"	movl %esp, %eax\n"
 	"	call trampoline_handler\n"
-	/* Replace saved sp with true return address. */
-	"	movl %eax, 15*4(%esp)\n"
 	RESTORE_REGS_STRING
+	/* In trampoline_handler(), 'regs->flags' is copied to 'regs->sp'. */
+	"	addl $4, %esp\n"
 	"	popfl\n"
 #endif
 	"	ret\n"
-	".size kretprobe_trampoline, .-kretprobe_trampoline\n"
+	".size __kretprobe_trampoline, .-__kretprobe_trampoline\n"
 );
-NOKPROBE_SYMBOL(kretprobe_trampoline);
-STACK_FRAME_NON_STANDARD(kretprobe_trampoline);
+NOKPROBE_SYMBOL(__kretprobe_trampoline);
+/*
+ * __kretprobe_trampoline() skips updating frame pointer. The frame pointer
+ * saved in trampoline_handler() points to the real caller function's
+ * frame pointer. Thus the __kretprobe_trampoline() doesn't have a
+ * standard stack frame with CONFIG_FRAME_POINTER=y.
+ * Let's mark it non-standard function. Anyway, FP unwinder can correctly
+ * unwind without the hint.
+ */
+STACK_FRAME_NON_STANDARD_FP(__kretprobe_trampoline);
 
+/* This is called from kretprobe_trampoline_handler(). */
+void arch_kretprobe_fixup_return(struct pt_regs *regs,
+				 kprobe_opcode_t *correct_ret_addr)
+{
+	unsigned long *frame_pointer = &regs->sp + 1;
+
+	/* Replace fake return address with real one. */
+	*frame_pointer = (unsigned long)correct_ret_addr;
+}
 
 /*
- * Called from kretprobe_trampoline
+ * Called from __kretprobe_trampoline
  */
-__used __visible void *trampoline_handler(struct pt_regs *regs)
+__used __visible void trampoline_handler(struct pt_regs *regs)
 {
+	unsigned long *frame_pointer;
+
 	/* fixup registers */
 	regs->cs = __KERNEL_CS;
 #ifdef CONFIG_X86_32
 	regs->gs = 0;
 #endif
-	regs->ip = (unsigned long)&kretprobe_trampoline;
+	regs->ip = (unsigned long)&__kretprobe_trampoline;
 	regs->orig_ax = ~0UL;
+	regs->sp += sizeof(long);
+	frame_pointer = &regs->sp + 1;
 
-	return (void *)kretprobe_trampoline_handler(regs, &kretprobe_trampoline, &regs->sp);
+	/*
+	 * The return address at 'frame_pointer' is recovered by the
+	 * arch_kretprobe_fixup_return() which called from the
+	 * kretprobe_trampoline_handler().
+	 */
+	kretprobe_trampoline_handler(regs, frame_pointer);
+
+	/*
+	 * Copy FLAGS to 'pt_regs::sp' so that __kretprobe_trapmoline()
+	 * can do RET right after POPF.
+	 */
+	regs->sp = regs->flags;
 }
 NOKPROBE_SYMBOL(trampoline_handler);
 

arch/x86/kernel/kprobes/ftrace.c

···
 	if (bit < 0)
 		return;
 
-	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (unlikely(!p) || kprobe_disabled(p))
 		goto out;
···
 		__this_cpu_write(current_kprobe, NULL);
 	}
 out:
-	preempt_enable_notrace();
 	ftrace_test_recursion_unlock(bit);
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);

arch/x86/kernel/kprobes/opt.c

···
 
 /* Check the addr is within the optimized instructions. */
 int arch_within_optimized_kprobe(struct optimized_kprobe *op,
-				 unsigned long addr)
+				 kprobe_opcode_t *addr)
 {
-	return ((unsigned long)op->kp.addr <= addr &&
-		(unsigned long)op->kp.addr + op->optinsn.size > addr);
+	return (op->kp.addr <= addr &&
+		op->kp.addr + op->optinsn.size > addr);
 }
 
 /* Free optimized instruction slot */

arch/x86/kernel/trace.c

···
 	unregister_trace_local_timer_exit(trace_intel_irq_exit, "local_timer");
 	unregister_trace_local_timer_entry(trace_intel_irq_entry, NULL);
 }
-#endif /* CONFIG_OSNOISE_TRAECR && CONFIG_X86_LOCAL_APIC */
+#endif /* CONFIG_OSNOISE_TRACER && CONFIG_X86_LOCAL_APIC */

arch/x86/kernel/unwind_frame.c

···
 	else {
 		addr_p = unwind_get_return_address_ptr(state);
 		addr = READ_ONCE_TASK_STACK(state->task, *addr_p);
-		state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-						  addr, addr_p);
+		state->ip = unwind_recover_ret_addr(state, addr, addr_p);
 	}
 
 	/* Save the original stack pointer for unwind_dump(): */

arch/x86/kernel/unwind_guess.c

···
 
 	addr = READ_ONCE_NOCHECK(*state->sp);
 
-	return ftrace_graph_ret_addr(state->task, &state->graph_idx,
-				     addr, state->sp);
+	return unwind_recover_ret_addr(state, addr, state->sp);
 }
 EXPORT_SYMBOL_GPL(unwind_get_return_address);
 

arch/x86/kernel/unwind_orc.c

···
 		if (!deref_stack_reg(state, ip_p, &state->ip))
 			goto err;
 
-		state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-						  state->ip, (void *)ip_p);
-
+		state->ip = unwind_recover_ret_addr(state, state->ip,
+						    (unsigned long *)ip_p);
 		state->sp = sp;
 		state->regs = NULL;
 		state->prev_regs = NULL;
···
 					 (void *)orig_ip);
 			goto err;
 		}
-
+		/*
+		 * There is a small chance to interrupt at the entry of
+		 * __kretprobe_trampoline() where the ORC info doesn't exist.
+		 * That point is right after the RET to __kretprobe_trampoline()
+		 * which was modified return address.
+		 * At that point, the @addr_p of the unwind_recover_kretprobe()
+		 * (this has to point the address of the stack entry storing
+		 * the modified return address) must be "SP - (a stack entry)"
+		 * because SP is incremented by the RET.
+		 */
+		state->ip = unwind_recover_kretprobe(state, state->ip,
+				(unsigned long *)(state->sp - sizeof(long)));
 		state->regs = (struct pt_regs *)sp;
 		state->prev_regs = NULL;
 		state->full_regs = true;
···
 					 (void *)orig_ip);
 			goto err;
 		}
+		/* See UNWIND_HINT_TYPE_REGS case comment. */
+		state->ip = unwind_recover_kretprobe(state, state->ip,
+				(unsigned long *)(state->sp - sizeof(long)));
 
 		if (state->full_regs)
 			state->prev_regs = state->regs;

fs/tracefs/inode.c

···
 	if (unlikely(!inode))
 		return failed_creating(dentry);
 
-	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
+	/* Do not set bits for OTH */
+	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUSR| S_IRGRP | S_IXUSR | S_IXGRP;
 	inode->i_op = ops;
 	inode->i_fop = &simple_dir_operations;
 

include/asm-generic/vmlinux.lds.h

···
  * Need to also make ftrace_stub_graph point to ftrace_stub
  * so that the same stub location may have different protocols
  * and not mess up with C verifiers.
+ *
+ * ftrace_ops_list_func will be defined as arch_ftrace_ops_list_func
+ * as some archs will have a different prototype for that function
+ * but ftrace_ops_list_func() will have a single prototype.
  */
 #define MCOUNT_REC()	. = ALIGN(8);				\
 			__start_mcount_loc = .;			\
 			KEEP(*(__mcount_loc))			\
 			KEEP(*(__patchable_function_entries))	\
 			__stop_mcount_loc = .;			\
-			ftrace_stub_graph = ftrace_stub;
+			ftrace_stub_graph = ftrace_stub;	\
+			ftrace_ops_list_func = arch_ftrace_ops_list_func;
 #else
 # ifdef CONFIG_FUNCTION_TRACER
-#  define MCOUNT_REC()	ftrace_stub_graph = ftrace_stub;
+#  define MCOUNT_REC()	ftrace_stub_graph = ftrace_stub;	\
+			ftrace_ops_list_func = arch_ftrace_ops_list_func;
 # else
 #  define MCOUNT_REC()
 # endif

include/linux/bootconfig.h

···
  * Author: Masami Hiramatsu <[e-mail]>
  */
 
+#ifdef __KERNEL__
 #include <linux/kernel.h>
 #include <linux/types.h>
+#else /* !__KERNEL__ */
+/*
+ * NOTE: This is only for tools/bootconfig, because tools/bootconfig will
+ * run the parser sanity test.
+ * This does NOT mean linux/bootconfig.h is available in the user space.
+ * However, if you change this file, please make sure the tools/bootconfig
+ * has no issue on building and running.
+ */
+#endif
 
 #define BOOTCONFIG_MAGIC	"#BOOTCONFIG\n"
 #define BOOTCONFIG_MAGIC_LEN	12
···
  * The checksum will be used with the BOOTCONFIG_MAGIC and the size for
  * embedding the bootconfig in the initrd image.
  */
-static inline __init u32 xbc_calc_checksum(void *data, u32 size)
+static inline __init uint32_t xbc_calc_checksum(void *data, uint32_t size)
 {
 	unsigned char *p = data;
-	u32 ret = 0;
+	uint32_t ret = 0;
 
 	while (size--)
 		ret += *p++;
···
 
 /* XBC tree node */
 struct xbc_node {
-	u16 next;
-	u16 child;
-	u16 parent;
-	u16 data;
+	uint16_t next;
+	uint16_t child;
+	uint16_t parent;
+	uint16_t data;
 } __attribute__ ((__packed__));
 
 #define XBC_KEY		0
···
 }
 
 /* XBC node initializer */
-int __init xbc_init(char *buf, const char **emsg, int *epos);
+int __init xbc_init(const char *buf, size_t size, const char **emsg, int *epos);
 
+/* XBC node and size information */
+int __init xbc_get_info(int *node_size, size_t *data_size);
 
 /* XBC cleanup data structures */
-void __init xbc_destroy_all(void);
-
-/* Debug dump functions */
-void __init xbc_debug_dump(void);
+void __init xbc_exit(void);
 
 #endif

include/linux/ftrace.h

···
 #define ARCH_SUPPORTS_FTRACE_OPS 0
 #endif
 
+#ifdef CONFIG_FUNCTION_TRACER
+struct ftrace_ops;
+struct ftrace_regs;
 /*
  * If the arch's mcount caller does not support all of ftrace's
  * features, then it must call an indirect function that
  * does. Or at least does enough to prevent any unwelcome side effects.
+ *
+ * Also define the function prototype that these architectures use
+ * to call the ftrace_ops_list_func().
  */
 #if !ARCH_SUPPORTS_FTRACE_OPS
 # define FTRACE_FORCE_LIST_FUNC 1
+void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
 #else
 # define FTRACE_FORCE_LIST_FUNC 0
+void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+			       struct ftrace_ops *op, struct ftrace_regs *fregs);
 #endif
+#endif /* CONFIG_FUNCTION_TRACER */
 
 /* Main tracing buffer and events set up */
 #ifdef CONFIG_TRACING
···
 extern int
 ftrace_enable_sysctl(struct ctl_table *table, int write,
 		     void *buffer, size_t *lenp, loff_t *ppos);
-
-struct ftrace_ops;
 
 #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
 
···
 				unsigned long old_addr,
 				unsigned long new_addr);
 unsigned long ftrace_find_rec_direct(unsigned long ip);
+int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
+int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
+int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
+
 #else
+struct ftrace_ops;
 # define ftrace_direct_func_count 0
 static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
 {
···
 static inline unsigned long ftrace_find_rec_direct(unsigned long ip)
 {
 	return 0;
+}
+static inline int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+	return -ENODEV;
+}
+static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+	return -ENODEV;
+}
+static inline int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+	return -ENODEV;
 }
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
 
···
 	return false;
 }
 #endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#ifndef ftrace_graph_func
+#define ftrace_graph_func ftrace_stub
+#define FTRACE_OPS_GRAPH_STUB FTRACE_OPS_FL_STUB
+#else
+#define FTRACE_OPS_GRAPH_STUB 0
+#endif
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 
 /* totally disable ftrace - can not re-enable after this */
 void ftrace_kill(void);

include/linux/kprobes.h

···
 #define _LINUX_KPROBES_H
 /*
  *  Kernel Probes (KProbes)
- *  include/linux/kprobes.h
  *
  * Copyright (C) IBM Corporation, 2002, 2004
  *
···
 #define KPROBE_REENTER		0x00000004
 #define KPROBE_HIT_SSDONE	0x00000008
 
-#else /* CONFIG_KPROBES */
+#else /* !CONFIG_KPROBES */
 #include <asm-generic/kprobes.h>
 typedef int kprobe_opcode_t;
 struct arch_specific_insn {
···
 #define KPROBE_FLAG_FTRACE	8 /* probe is using ftrace */
 
 /* Has this kprobe gone ? */
-static inline int kprobe_gone(struct kprobe *p)
+static inline bool kprobe_gone(struct kprobe *p)
 {
 	return p->flags & KPROBE_FLAG_GONE;
 }
 
 /* Is this kprobe disabled ? */
-static inline int kprobe_disabled(struct kprobe *p)
+static inline bool kprobe_disabled(struct kprobe *p)
 {
 	return p->flags & (KPROBE_FLAG_DISABLED | KPROBE_FLAG_GONE);
 }
 
 /* Is this kprobe really running optimized path ? */
-static inline int kprobe_optimized(struct kprobe *p)
+static inline bool kprobe_optimized(struct kprobe *p)
 {
 	return p->flags & KPROBE_FLAG_OPTIMIZED;
 }
 
 /* Is this kprobe uses ftrace ? */
-static inline int kprobe_ftrace(struct kprobe *p)
+static inline bool kprobe_ftrace(struct kprobe *p)
 {
 	return p->flags & KPROBE_FLAG_FTRACE;
 }
···
 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
-/*
- * For #ifdef avoidance:
- */
-static inline int kprobes_built_in(void)
-{
-	return 1;
-}
-
 extern void kprobe_busy_begin(void);
 extern void kprobe_busy_end(void);
 
···
 				   struct pt_regs *regs);
 extern int arch_trampoline_kprobe(struct kprobe *p);
 
+void arch_kretprobe_fixup_return(struct pt_regs *regs,
+				 kprobe_opcode_t *correct_ret_addr);
+
+void __kretprobe_trampoline(void);
+/*
+ * Since some architecture uses structured function pointer,
+ * use dereference_function_descriptor() to get real function address.
+ */
+static nokprobe_inline void *kretprobe_trampoline_addr(void)
+{
+	return dereference_kernel_function_descriptor(__kretprobe_trampoline);
+}
+
 /* If the trampoline handler called from a kprobe, use this version */
 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
-				void *trampoline_address,
-				void *frame_pointer);
+					     void *frame_pointer);
 
 static nokprobe_inline
 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs,
-				void *trampoline_address,
-				void *frame_pointer)
+					   void *frame_pointer)
 {
 	unsigned long ret;
 	/*
···
 	 * be running at this point.
 	 */
 	kprobe_busy_begin();
-	ret = __kretprobe_trampoline_handler(regs, trampoline_address, frame_pointer);
+	ret = __kretprobe_trampoline_handler(regs, frame_pointer);
 	kprobe_busy_end();
 
 	return ret;
···
 	return READ_ONCE(ri->rph->rp);
 }
 
-#else /* CONFIG_KRETPROBES */
+#else /* !CONFIG_KRETPROBES */
 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 					struct pt_regs *regs)
 {
···
 }
 #endif /* CONFIG_KRETPROBES */
 
+/* Markers of '_kprobe_blacklist' section */
+extern unsigned long __start_kprobe_blacklist[];
+extern unsigned long __stop_kprobe_blacklist[];
+
 extern struct kretprobe_blackpoint kretprobe_blacklist[];
 
 #ifdef CONFIG_KPROBES_SANITY_TEST
 extern int init_test_probes(void);
-#else
+#else /* !CONFIG_KPROBES_SANITY_TEST */
 static inline int init_test_probes(void)
 {
 	return 0;
···
 #define KPROBE_OPTINSN_PAGE_SYM		"kprobe_optinsn_page"
 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
 			     unsigned long *value, char *type, char *sym);
-#else /* __ARCH_WANT_KPROBES_INSN_SLOT */
+#else /* !__ARCH_WANT_KPROBES_INSN_SLOT */
 #define DEFINE_INSN_CACHE_OPS(__name)					\
 static inline bool is_kprobe_##__name##_slot(unsigned long addr)	\
 {									\
···
 				    struct list_head *done_list);
 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
-					unsigned long addr);
+					kprobe_opcode_t *addr);
 
 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
 
···
 extern int proc_kprobes_optimization_handler(struct ctl_table *table,
 					     int write, void *buffer,
 					     size_t *length, loff_t *ppos);
-#endif
+#endif /* CONFIG_SYSCTL */
 extern void wait_for_kprobe_optimizer(void);
-#else
+#else /* !CONFIG_OPTPROBES */
 static inline void wait_for_kprobe_optimizer(void) { }
 #endif /* CONFIG_OPTPROBES */
+
 #ifdef CONFIG_KPROBES_ON_FTRACE
 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 				  struct ftrace_ops *ops, struct ftrace_regs *fregs);
 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
-#endif
-
-int arch_check_ftrace_location(struct kprobe *p);
+#else
+static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
+{
+	return -EINVAL;
+}
+#endif /* CONFIG_KPROBES_ON_FTRACE */
 
 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 struct kprobe *get_kprobe(void *addr);
···
 /* kprobe_running() will just return the current_kprobe on this CPU */
 static inline struct kprobe *kprobe_running(void)
 {
-	return (__this_cpu_read(current_kprobe));
+	return __this_cpu_read(current_kprobe);
 }
 
 static inline void reset_current_kprobe(void)
···
 void unregister_kprobe(struct kprobe *p);
 int register_kprobes(struct kprobe **kps, int num);
 void unregister_kprobes(struct kprobe **kps, int num);
-unsigned long arch_deref_entry_point(void *);
 
 int register_kretprobe(struct kretprobe *rp);
 void unregister_kretprobe(struct kretprobe *rp);
···
 			    char *type, char *sym);
 #else /* !CONFIG_KPROBES: */
 
-static inline int kprobes_built_in(void)
-{
-	return 0;
-}
 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
 	return 0;
···
 }
 static inline int register_kprobe(struct kprobe *p)
 {
-	return -ENOSYS;
+	return -EOPNOTSUPP;
 }
 static inline int register_kprobes(struct kprobe **kps, int num)
 {
-	return -ENOSYS;
+	return -EOPNOTSUPP;
 }
 static inline void unregister_kprobe(struct kprobe *p)
 {
···
 }
 static inline int register_kretprobe(struct kretprobe *rp)
 {
-	return -ENOSYS;
+	return -EOPNOTSUPP;
 }
 static inline int register_kretprobes(struct kretprobe **rps, int num)
 {
-	return -ENOSYS;
+	return -EOPNOTSUPP;
 }
 static inline void unregister_kretprobe(struct kretprobe *rp)
 {
···
 }
 static inline int disable_kprobe(struct kprobe *kp)
 {
-	return -ENOSYS;
+	return -EOPNOTSUPP;
 }
 static inline int enable_kprobe(struct kprobe *kp)
 {
-	return -ENOSYS;
+	return -EOPNOTSUPP;
 }
 
 static inline bool within_kprobe_blacklist(unsigned long addr)
···
 	return -ERANGE;
 }
 #endif /* CONFIG_KPROBES */
+
 static inline int disable_kretprobe(struct kretprobe *rp)
 {
 	return disable_kprobe(&rp->kp);
···
 {
 	return false;
 }
-#endif
+#endif /* !CONFIG_KPROBES */
+
 #ifndef CONFIG_OPTPROBES
 static inline bool is_kprobe_optinsn_slot(unsigned long addr)
 {
 	return false;
+}
+#endif /* !CONFIG_OPTPROBES */
+
+#ifdef CONFIG_KRETPROBES
+static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
+{
+	return (void *)addr == kretprobe_trampoline_addr();
+}
+
+unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
+				      struct llist_node **cur);
+#else
+static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
+{
+	return false;
+}
+
+static nokprobe_inline
+unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
+				      struct llist_node **cur)
+{
+	return 0;
 }
 #endif
 
···
 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
 					      unsigned int trap)
 {
-	if (!kprobes_built_in())
+	if (!IS_ENABLED(CONFIG_KPROBES))
 		return false;
 	if (user_mode(regs))
 		return false;

include/linux/objtool.h

···
 	static void __used __section(".discard.func_stack_frame_non_standard") \
 		*__func_stack_frame_non_standard_##func = func
 
+/*
+ * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
+ * for the case where a function is intentionally missing frame pointer setup,
+ * but otherwise needs objtool/ORC coverage when frame pointers are disabled.
+ */
+#ifdef CONFIG_FRAME_POINTER
+#define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
+#else
+#define STACK_FRAME_NON_STANDARD_FP(func)
+#endif
+
 #else /* __ASSEMBLY__ */
 
 /*
···
 #define UNWIND_HINT(sp_reg, sp_offset, type, end)	\
 	"\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
+#define STACK_FRAME_NON_STANDARD_FP(func)
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0

include/linux/preempt.h

···
 /* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */
 #include <asm/preempt.h>
 
+/**
+ * interrupt_context_level - return interrupt context level
+ *
+ * Returns the current interrupt context level.
+ *  0 - normal context
+ *  1 - softirq context
+ *  2 - hardirq context
+ *  3 - NMI context
+ */
+static __always_inline unsigned char interrupt_context_level(void)
+{
+	unsigned long pc = preempt_count();
+	unsigned char level = 0;
+
+	level += !!(pc & (NMI_MASK));
+	level += !!(pc & (NMI_MASK | HARDIRQ_MASK));
+	level += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET));
+
+	return level;
+}
+
 #define nmi_count()	(preempt_count() & NMI_MASK)
 #define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
 #ifdef CONFIG_PREEMPT_RT

include/linux/trace_events.h

···
 	}								\
 	early_initcall(trace_init_perf_perm_##name);
 
-#define PERF_MAX_TRACE_SIZE	2048
+#define PERF_MAX_TRACE_SIZE	8192
 
 #define MAX_FILTER_STR_VAL	256	/* Should handle KSYM_SYMBOL_LEN */
 

include/linux/trace_recursion.h

···
 
 static __always_inline int trace_get_context_bit(void)
 {
-	unsigned long pc = preempt_count();
+	unsigned char bit = interrupt_context_level();
 
-	if (!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
-		return TRACE_CTX_NORMAL;
-	else
-		return pc & NMI_MASK ? TRACE_CTX_NMI :
-			pc & HARDIRQ_MASK ? TRACE_CTX_IRQ : TRACE_CTX_SOFTIRQ;
+	return TRACE_CTX_NORMAL - bit;
 }
 
 #ifdef CONFIG_FTRACE_RECORD_RECURSION
···
 # define do_ftrace_record_recursion(ip, pip)	do { } while (0)
 #endif
 
+/*
+ * Preemption is promised to be disabled when return bit >= 0.
+ */
 static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip,
 							int start)
 {
···
 	bit = trace_get_context_bit() + start;
 	if (unlikely(val & (1 << bit))) {
 		/*
-		 * It could be that preempt_count has not been updated during
-		 * a switch between contexts. Allow for a single recursion.
+		 * If an interrupt occurs during a trace, and another trace
+		 * happens in that interrupt but before the preempt_count is
+		 * updated to reflect the new interrupt context, then this
+		 * will think a recursion occurred, and the event will be dropped.
+		 * Let a single instance happen via the TRANSITION_BIT to
+		 * not drop those events.
 		 */
 		bit = TRACE_CTX_TRANSITION + start;
 		if (val & (1 << bit)) {
···
 	current->trace_recursion = val;
 	barrier();
 
+	preempt_disable_notrace();
+
 	return bit;
 }
 
+/*
+ * Preemption will be enabled (if it was previously enabled).
+ */
 static __always_inline void trace_clear_recursion(int bit)
 {
+	preempt_enable_notrace();
 	barrier();
 	trace_recursion_clear(bit);
 }
···
  * tracing recursed in the same context (normal vs interrupt),
  *
  * Returns: -1 if a recursion happened.
- *           >= 0 if no recursion
+ *           >= 0 if no recursion.
  */
 static __always_inline int ftrace_test_recursion_trylock(unsigned long ip,
 							 unsigned long parent_ip)

init/main.c

···
 	const char *msg;
 	int pos;
 	u32 size, csum;
-	char *data, *copy, *err;
+	char *data, *err;
 	int ret;
 
 	/* Cut out the bootconfig data even if we have no bootconfig option */
···
 		return;
 	}
 
-	copy = memblock_alloc(size + 1, SMP_CACHE_BYTES);
-	if (!copy) {
-		pr_err("Failed to allocate memory for bootconfig\n");
-		return;
-	}
-
-	memcpy(copy, data, size);
-	copy[size] = '\0';
-
-	ret = xbc_init(copy, &msg, &pos);
+	ret = xbc_init(data, size, &msg, &pos);
 	if (ret < 0) {
 		if (pos < 0)
 			pr_err("Failed to init bootconfig: %s.\n", msg);
···
 			pr_err("Failed to parse bootconfig: %s at %d.\n",
 				msg, pos);
 	} else {
+		xbc_get_info(&ret, NULL);
 		pr_info("Load bootconfig: %d bytes %d nodes\n", size, ret);
 		/* keys starting with "kernel." are passed via cmdline */
 		extra_command_line = xbc_make_cmdline("kernel");
···
 
 static void __init exit_boot_config(void)
 {
-	xbc_destroy_all();
+	xbc_exit();
 }
 
 #else	/* !CONFIG_BOOT_CONFIG */

kernel/Makefile

···
 obj-$(CONFIG_IKCONFIG) += configs.o
 obj-$(CONFIG_IKHEADERS) += kheaders.o
 obj-$(CONFIG_SMP) += stop_machine.o
-obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
 obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
 obj-$(CONFIG_AUDITSYSCALL) += auditsc.o audit_watch.o audit_fsnotify.o audit_tree.o
 obj-$(CONFIG_GCOV_KERNEL) += gcov/

kernel/events/internal.h

···
 
 static inline int get_recursion_context(int *recursion)
 {
-	unsigned int pc = preempt_count();
-	unsigned char rctx = 0;
-
-	rctx += !!(pc & (NMI_MASK));
-	rctx += !!(pc & (NMI_MASK | HARDIRQ_MASK));
-	rctx += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET));
+	unsigned char rctx = interrupt_context_level();
 
 	if (recursion[rctx])
 		return -1;

kernel/kprobes.c

···
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *  Kernel Probes (KProbes)
- *  kernel/kprobes.c
  *
  * Copyright (C) IBM Corporation, 2002, 2004
  *
···
  *		<[e-mail]> and Prasanna S Panchamukhi
  *		<[e-mail]> added function-return probes.
  */
+
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/kprobes.h>
 #include <linux/hash.h>
 #include <linux/init.h>
···
 
 static int kprobes_initialized;
 /* kprobe_table can be accessed by
- * - Normal hlist traversal and RCU add/del under kprobe_mutex is held.
+ * - Normal hlist traversal and RCU add/del under 'kprobe_mutex' is held.
  * Or
  * - RCU hlist traversal under disabling preempt (breakpoint handlers)
  */
 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
 
-/* NOTE: change this value only with kprobe_mutex held */
+/* NOTE: change this value only with 'kprobe_mutex' held */
 static bool kprobes_all_disarmed;
 
-/* This protects kprobe_table and optimizing_list */
+/* This protects 'kprobe_table' and 'optimizing_list' */
 static DEFINE_MUTEX(kprobe_mutex);
-static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
+static DEFINE_PER_CPU(struct kprobe *, kprobe_instance);
 
 kprobe_opcode_t * __weak kprobe_lookup_name(const char *name,
 					unsigned int __unused)
···
 	return ((kprobe_opcode_t *)(kallsyms_lookup_name(name)));
 }
 
-/* Blacklist -- list of struct kprobe_blacklist_entry */
+/*
+ * Blacklist -- list of 'struct kprobe_blacklist_entry' to store info where
+ * kprobes can not probe.
+ */
 static LIST_HEAD(kprobe_blacklist);
 
 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 /*
- * kprobe->ainsn.insn points to the copy of the instruction to be
+ * 'kprobe::ainsn.insn' points to the copy of the instruction to be
  * single-stepped. x86_64, POWER4 and above have no-exec support and
  * stepping on the instruction on a vmalloced/kmalloced/data page
  * is a recipe for disaster
···
 
 void __weak *alloc_insn_page(void)
 {
+	/*
+	 * Use module_alloc() so this page is within +/- 2GB of where the
+	 * kernel image and loaded module images reside. This is required
+	 * for most of the architectures.
+	 * (e.g. x86-64 needs this to handle the %rip-relative fixups.)
+	 */
 	return module_alloc(PAGE_SIZE);
 }
 
···
 	list_for_each_entry_rcu(kip, &c->pages, list) {
 		if (kip->nused < slots_per_page(c)) {
 			int i;
+
 			for (i = 0; i < slots_per_page(c); i++) {
 				if (kip->slot_used[i] == SLOT_CLEAN) {
 					kip->slot_used[i] = SLOT_USED;
···
 	if (!kip)
 		goto out;
 
-	/*
-	 * Use module_alloc so this page is within +/- 2GB of where the
-	 * kernel image and loaded module images reside. This is required
-	 * so x86_64 can correctly handle the %rip-relative fixups.
-	 */
 	kip->insns = c->alloc();
 	if (!kip->insns) {
 		kfree(kip);
···
 	return slot;
 }
 
-/* Return 1 if all garbages are collected, otherwise 0. */
-static int collect_one_slot(struct kprobe_insn_page *kip, int idx)
+/* Return true if all garbages are collected, otherwise false. */
+static bool collect_one_slot(struct kprobe_insn_page *kip, int idx)
 {
 	kip->slot_used[idx] = SLOT_CLEAN;
 	kip->nused--;
···
 			kip->cache->free(kip->insns);
 			kfree(kip);
 		}
-		return 1;
+		return true;
 	}
-	return 0;
+	return false;
 }
 
 static int collect_garbage_slots(struct kprobe_insn_cache *c)
···
 
 	list_for_each_entry_safe(kip, next, &c->pages, list) {
 		int i;
+
 		if (kip->ngarbage == 0)
 			continue;
 		kip->ngarbage = 0;	/* we will collect all garbages */
···
 	list_for_each_entry_rcu(kip, &c->pages, list) {
 		if ((*symnum)--)
 			continue;
-		strlcpy(sym, c->sym, KSYM_NAME_LEN);
+		strscpy(sym, c->sym, KSYM_NAME_LEN);
 		*type = 't';
 		*value = (unsigned long)kip->insns;
 		ret = 0;
···
 
 /*
  * This routine is called either:
- * 	- under the kprobe_mutex - during kprobe_[un]register()
- * 				OR
- * 	- with preemption disabled - from arch/xxx/kernel/kprobes.c
+ *	- under the 'kprobe_mutex' - during kprobe_[un]register().
+ *				OR
+ *	- with preemption disabled - from architecture specific code.
  */
 struct kprobe *get_kprobe(void *addr)
 {
···
 
 static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
 
-/* Return true if the kprobe is an aggregator */
-static inline int kprobe_aggrprobe(struct kprobe *p)
+/* Return true if 'p' is an aggregator */
+static inline bool kprobe_aggrprobe(struct kprobe *p)
 {
 	return p->pre_handler == aggr_pre_handler;
 }
 
-/* Return true(!0) if the kprobe is unused */
-static inline int kprobe_unused(struct kprobe *p)
+/* Return true if 'p' is unused */
+static inline bool kprobe_unused(struct kprobe *p)
 {
 	return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
 	       list_empty(&p->list);
 }
 
-/*
- * Keep all fields in the kprobe consistent
- */
+/* Keep all fields in the kprobe consistent. */
 static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
 {
 	memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
···
 }
 
 #ifdef CONFIG_OPTPROBES
-/* NOTE: change this value only with kprobe_mutex held */
+/* NOTE: This is protected by 'kprobe_mutex'. */
 static bool kprobes_allow_optimization;
 
 /*
- * Call all pre_handler on the list, but ignores its return value.
+ * Call all 'kprobe::pre_handler' on the list, but ignores its return value.
  * This must be called from arch-dep optimized caller.
  */
 void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
···
 	kfree(op);
 }
 
-/* Return true(!0) if the kprobe is ready for optimization. */
+/* Return true if the kprobe is ready for optimization. */
 static inline int kprobe_optready(struct kprobe *p)
 {
 	struct optimized_kprobe *op;
···
 	return 0;
 }
 
-/* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
-static inline int kprobe_disarmed(struct kprobe *p)
+/* Return true if the kprobe is disarmed. Note: p must be on hash list */
+static inline bool kprobe_disarmed(struct kprobe *p)
 {
 	struct optimized_kprobe *op;
 
···
 	return kprobe_disabled(p) && list_empty(&op->list);
 }
 
-/* Return true(!0) if the probe is queued on (un)optimizing lists */
-static int kprobe_queued(struct kprobe *p)
+/* Return true if the probe is queued on (un)optimizing lists */
+static bool kprobe_queued(struct kprobe *p)
 {
 	struct optimized_kprobe *op;
 
 	if (kprobe_aggrprobe(p)) {
 		op = container_of(p, struct optimized_kprobe, kp);
 		if (!list_empty(&op->list))
-			return 1;
+			return true;
 	}
-	return 0;
+	return false;
 }
 
 /*
  * Return an optimized kprobe whose optimizing code replaces
- * instructions including addr (exclude breakpoint).
+ * instructions including 'addr' (exclude breakpoint).
  */
-static struct kprobe *get_optimized_kprobe(unsigned long addr)
+static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *addr)
 {
 	int i;
 	struct kprobe *p = NULL;
 	struct optimized_kprobe *op;
 
 	/* Don't check i == 0, since that is a breakpoint case. */
-	for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
-		p = get_kprobe((void *)(addr - i));
+	for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++)
+		p = get_kprobe(addr - i);
 
 	if (p && kprobe_optready(p)) {
 		op = container_of(p, struct optimized_kprobe, kp);
···
 	return NULL;
 }
 
-/* Optimization staging list, protected by kprobe_mutex */
+/* Optimization staging list, protected by 'kprobe_mutex' */
 static LIST_HEAD(optimizing_list);
 static LIST_HEAD(unoptimizing_list);
 static LIST_HEAD(freeing_list);
···
 
 /*
  * Optimize (replace a breakpoint with a jump) kprobes listed on
- * optimizing_list.
+ * 'optimizing_list'.
  */
 static void do_optimize_kprobes(void)
 {
 	lockdep_assert_held(&text_mutex);
 	/*
-	 * The optimization/unoptimization refers online_cpus via
-	 * stop_machine() and cpu-hotplug modifies online_cpus.
-	 * And same time, text_mutex will be held in cpu-hotplug and here.
-	 * This combination can cause a deadlock (cpu-hotplug try to lock
-	 * text_mutex but stop_machine can not be done because online_cpus
-	 * has been changed)
-	 * To avoid this deadlock, caller must have locked cpu hotplug
-	 * for preventing cpu-hotplug outside of text_mutex locking.
+	 * The optimization/unoptimization refers 'online_cpus' via
+	 * stop_machine() and cpu-hotplug modifies the 'online_cpus'.
+	 * And same time, 'text_mutex' will be held in cpu-hotplug and here.
+	 * This combination can cause a deadlock (cpu-hotplug tries to lock
+	 * 'text_mutex' but stop_machine() can not be done because
+	 * the 'online_cpus' has been changed)
+	 * To avoid this deadlock, caller must have locked cpu-hotplug
+	 * for preventing cpu-hotplug outside of 'text_mutex' locking.
 	 */
 	lockdep_assert_cpus_held();
 
···
 
 /*
  * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
- * if need) kprobes listed on unoptimizing_list.
+ * if need) kprobes listed on 'unoptimizing_list'.
  */
 static void do_unoptimize_kprobes(void)
 {
···
 		return;
 
 	arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
-	/* Loop free_list for disarming */
+	/* Loop on 'freeing_list' for disarming */
 	list_for_each_entry_safe(op, tmp, &freeing_list, list) {
 		/* Switching from detour code to origin */
 		op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
···
 			/*
 			 * Remove unused probes from hash list. After waiting
 			 * for synchronization, these probes are reclaimed.
-			 * (reclaiming is done by do_free_cleaned_kprobes.)
+			 * (reclaiming is done by do_free_cleaned_kprobes().)
 			 */
 			hlist_del_rcu(&op->kp.hlist);
 		} else
···
 	}
 }
 
-/* Reclaim all kprobes on the free_list */
+/* Reclaim all kprobes on the 'freeing_list' */
 static void do_free_cleaned_kprobes(void)
 {
 	struct optimized_kprobe *op, *tmp;
···
 	while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
 		mutex_unlock(&kprobe_mutex);
 
-		/* this will also make optimizing_work execute immmediately */
+		/* This will also make 'optimizing_work' execute immmediately */
 		flush_delayed_work(&optimizing_work);
-		/* @optimizing_work might not have been queued yet, relax */
+		/* 'optimizing_work' might not have been queued yet, relax */
 		cpu_relax();
 
 		mutex_lock(&kprobe_mutex);
···
 	    (kprobe_disabled(p) || kprobes_all_disarmed))
 		return;
 
-	/* kprobes with post_handler can not be optimized */
+	/* kprobes with 'post_handler' can not be optimized */
 	if (p->post_handler)
 		return;
 
···
 	}
 	op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
 
-	/* On unoptimizing/optimizing_list, op must have OPTIMIZED flag */
+	/*
+	 * On the 'unoptimizing_list' and 'optimizing_list',
+	 * 'op' must have OPTIMIZED flag
+	 */
 	if (WARN_ON_ONCE(!list_empty(&op->list)))
 		return;
 
···
 	WARN_ON_ONCE(list_empty(&op->list));
 	/* Enable the probe again */
 	ap->flags &= ~KPROBE_FLAG_DISABLED;
-	/* Optimize it again (remove from op->list) */
+	/* Optimize it again. (remove from 'op->list') */
 	if (!kprobe_optready(ap))
 		return -EINVAL;
 
···
 	__prepare_optimized_kprobe(op, p);
 }
 
-/* Allocate new optimized_kprobe and try to prepare optimized instructions */
+/* Allocate new optimized_kprobe and try to prepare optimized instructions. */
 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 {
 	struct optimized_kprobe *op;
···
 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
 
 /*
- * Prepare an optimized_kprobe and optimize it
- * NOTE: p must be a normal registered kprobe
+ * Prepare an optimized_kprobe and optimize it.
+ * NOTE: 'p' must be a normal registered kprobe.
  */
 static void try_to_optimize_kprobe(struct kprobe *p)
 {
 	struct kprobe *ap;
 	struct optimized_kprobe *op;
 
-	/* Impossible to optimize ftrace-based kprobe */
+	/* Impossible to optimize ftrace-based kprobe. */
 	if (kprobe_ftrace(p))
 		return;
 
-	/* For preparing optimization, jump_label_text_reserved() is called */
+	/* For preparing optimization, jump_label_text_reserved() is called. */
 	cpus_read_lock();
 	jump_label_lock();
 	mutex_lock(&text_mutex);
···
 
 	op = container_of(ap, struct optimized_kprobe, kp);
 	if (!arch_prepared_optinsn(&op->optinsn)) {
-		/* If failed to setup optimizing, fallback to kprobe */
+		/* If failed to setup optimizing, fallback to kprobe. */
 		arch_remove_optimized_kprobe(op);
 		kfree(op);
 		goto out;
 	}
 
 	init_aggr_kprobe(ap, p);
-	optimize_kprobe(ap);	/* This just kicks optimizer thread */
+	optimize_kprobe(ap);	/* This just kicks optimizer thread. */
 
 out:
 	mutex_unlock(&text_mutex);
···
 	unsigned int i;
 
 	mutex_lock(&kprobe_mutex);
-	/* If optimization is already allowed, just return */
+	/* If optimization is already allowed, just return. */
 	if (kprobes_allow_optimization)
 		goto out;
 
···
 				optimize_kprobe(p);
 	}
 	cpus_read_unlock();
-	printk(KERN_INFO "Kprobes globally optimized\n");
+	pr_info("kprobe jump-optimization is enabled. All kprobes are optimized if possible.\n");
 out:
 	mutex_unlock(&kprobe_mutex);
 }
···
 	unsigned int i;
 
 	mutex_lock(&kprobe_mutex);
-	/* If optimization is already prohibited, just return */
+	/* If optimization is already prohibited, just return. */
 	if (!kprobes_allow_optimization) {
 		mutex_unlock(&kprobe_mutex);
 		return;
···
 	cpus_read_unlock();
 	mutex_unlock(&kprobe_mutex);
 
-	/* Wait for unoptimizing completion */
+	/* Wait for unoptimizing completion. */
 	wait_for_kprobe_optimizer();
-	printk(KERN_INFO "Kprobes globally unoptimized\n");
+	pr_info("kprobe jump-optimization is disabled. All kprobes are based on software breakpoint.\n");
 }
 
 static DEFINE_MUTEX(kprobe_sysctl_mutex);
···
 }
 #endif /* CONFIG_SYSCTL */
 
-/* Put a breakpoint for a probe. Must be called with text_mutex locked */
+/* Put a breakpoint for a probe. */
 static void __arm_kprobe(struct kprobe *p)
 {
 	struct kprobe *_p;
 
-	/* Check collision with other optimized kprobes */
-	_p = get_optimized_kprobe((unsigned long)p->addr);
+	lockdep_assert_held(&text_mutex);
+
+	/* Find the overlapping optimized kprobes. */
+	_p = get_optimized_kprobe(p->addr);
 	if (unlikely(_p))
 		/* Fallback to unoptimized kprobe */
 		unoptimize_kprobe(_p, true);
···
 	optimize_kprobe(p);	/* Try to optimize (add kprobe to a list) */
 }
 
-/* Remove the breakpoint of a probe. Must be called with text_mutex locked */
+/* Remove the breakpoint of a probe. */
 static void __disarm_kprobe(struct kprobe *p, bool reopt)
 {
 	struct kprobe *_p;
+
+	lockdep_assert_held(&text_mutex);
 
 	/* Try to unoptimize */
 	unoptimize_kprobe(p, kprobes_all_disarmed);
 
 	if (!kprobe_queued(p)) {
 		arch_disarm_kprobe(p);
-		/* If another kprobe was blocked, optimize it. */
-		_p = get_optimized_kprobe((unsigned long)p->addr);
+		/* If another kprobe was blocked, re-optimize it. */
+		_p = get_optimized_kprobe(p->addr);
 		if (unlikely(_p) && reopt)
 			optimize_kprobe(_p);
 	}
-	/* TODO: reoptimize others after unoptimized this probe */
+	/*
+	 * TODO: Since unoptimization and real disarming will be done by
+	 * the worker thread, we can not check whether another probe are
+	 * unoptimized because of this probe here. It should be re-optimized
+	 * by the worker thread.
+	 */
 }
 
 #else /* !CONFIG_OPTPROBES */
···
 	 * unregistered.
 	 * Thus there should be no chance to reuse unused kprobe.
 	 */
-	printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
+	WARN_ON_ONCE(1);
 	return -EINVAL;
 }
 
···
 static int kprobe_ipmodify_enabled;
 static int kprobe_ftrace_enabled;
 
-/* Must ensure p->addr is really on ftrace */
-static int prepare_kprobe(struct kprobe *p)
-{
-	if (!kprobe_ftrace(p))
-		return arch_prepare_kprobe(p);
-
-	return arch_prepare_kprobe_ftrace(p);
-}
-
-/* Caller must lock kprobe_mutex */
 static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 			       int *cnt)
 {
 	int ret = 0;
 
+	lockdep_assert_held(&kprobe_mutex);
+
 	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
-	if (ret) {
-		pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n",
-			 p->addr, ret);
+	if (WARN_ONCE(ret < 0, "Failed to arm kprobe-ftrace at %pS (error %d)\n", p->addr, ret))
 		return ret;
-	}
 
 	if (*cnt == 0) {
 		ret = register_ftrace_function(ops);
-		if (ret) {
-			pr_debug("Failed to init kprobe-ftrace (%d)\n", ret);
+		if (WARN(ret < 0, "Failed to register kprobe-ftrace (error %d)\n", ret))
 			goto err_ftrace;
-		}
 	}
 
 	(*cnt)++;
···
 		ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
 }
 
-/* Caller must lock kprobe_mutex */
 static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 				  int *cnt)
 {
 	int ret = 0;
 
+	lockdep_assert_held(&kprobe_mutex);
+
 	if (*cnt == 1) {
 		ret = unregister_ftrace_function(ops);
-		if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (%d)\n", ret))
+		if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (error %d)\n", ret))
 			return ret;
 	}
 
 	(*cnt)--;
 
 	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
-	WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n",
+	WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (error %d)\n",
 		  p->addr, ret);
 	return ret;
 }
···
 		ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
 }
 #else	/* !CONFIG_KPROBES_ON_FTRACE */
-static inline int prepare_kprobe(struct kprobe *p)
-{
-	return arch_prepare_kprobe(p);
-}
-
 static inline int arm_kprobe_ftrace(struct kprobe *p)
 {
 	return -ENODEV;
···
 }
 #endif
 
-/* Arm a kprobe with text_mutex */
+static int prepare_kprobe(struct kprobe *p)
+{
+	/* Must ensure p->addr is really on ftrace */
+	if (kprobe_ftrace(p))
+		return arch_prepare_kprobe_ftrace(p);
+
+	return arch_prepare_kprobe(p);
+}
+
 static int arm_kprobe(struct kprobe *kp)
 {
 	if (unlikely(kprobe_ftrace(kp)))
···
 	return 0;
 }
 
-/* Disarm a kprobe with text_mutex */
 static int disarm_kprobe(struct kprobe *kp, bool reopt)
 {
 	if (unlikely(kprobe_ftrace(kp)))
···
 }
 NOKPROBE_SYMBOL(aggr_post_handler);
 
-/* Walks the list and increments nmissed count for multiprobe case */
+/* Walks the list and increments 'nmissed' if 'p' has child probes. */
 void kprobes_inc_nmissed_count(struct kprobe *p)
 {
 	struct kprobe *kp;
+
 	if (!kprobe_aggrprobe(p)) {
 		p->nmissed++;
 	} else {
 		list_for_each_entry_rcu(kp, &p->list, list)
 			kp->nmissed++;
 	}
-	return;
 }
 NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
 
···
 {
 	struct kretprobe *rp = get_kretprobe(ri);
 
-	if (likely(rp)) {
+	if (likely(rp))
 		freelist_add(&ri->freelist, &rp->freelist);
-	} else
+	else
 		call_rcu(&ri->rcu, free_rp_inst_rcu);
 }
 NOKPROBE_SYMBOL(recycle_rp_inst);
···
 
 /*
  * This function is called from delayed_put_task_struct() when a task is
- * dead and cleaned up to recycle any function-return probe instances
- * associated with this task. These left over instances represent probed
- * functions that have been called but will never return.
+ * dead and cleaned up to recycle any kretprobe instances associated with
+ * this task. These left over instances represent probed functions that
+ * have been called but will never return.
  */
 void kprobe_flush_task(struct task_struct *tk)
 {
···
 	}
 }
 
-/* Add the new probe to ap->list */
+/* Add the new probe to 'ap->list'. */
 static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
 {
 	if (p->post_handler)
···
 }
 
 /*
- * Fill in the required fields of the "manager kprobe". Replace the
- * earlier kprobe in the hlist with the manager kprobe
+ * Fill in the required fields of the aggregator kprobe. Replace the
+ * earlier kprobe in the hlist with the aggregator kprobe.
  */
 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
 {
-	/* Copy p's insn slot to ap */
+	/* Copy the insn slot of 'p' to 'ap'. */
 	copy_kprobe(p, ap);
 	flush_insn_slot(ap);
 	ap->addr = p->addr;
···
 }
 
 /*
- * This is the second or subsequent kprobe at the address - handle
- * the intricacies
+ * This registers the second or subsequent kprobe at the same address.
  */
 static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
 {
···
 	mutex_lock(&text_mutex);
 
 	if (!kprobe_aggrprobe(orig_p)) {
-		/* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
+		/* If 'orig_p' is not an 'aggr_kprobe', create new one. */
 		ap = alloc_aggr_kprobe(orig_p);
 		if (!ap) {
 			ret = -ENOMEM;
···
 		if (ret)
 			/*
 			 * Even if fail to allocate new slot, don't need to
-			 * free aggr_probe. It will be used next time, or
-			 * freed by unregister_kprobe.
+			 * free the 'ap'. It will be used next time, or
+			 * freed by unregister_kprobe().
 			 */
 			goto out;
 
···
 			    | KPROBE_FLAG_DISABLED;
 	}
 
-	/* Copy ap's insn slot to p */
+	/* Copy the insn slot of 'p' to 'ap'. */
 	copy_kprobe(ap, p);
 	ret = add_new_kprobe(ap, p);
 
···
 
 bool __weak arch_within_kprobe_blacklist(unsigned long addr)
 {
-	/* The __kprobes marked functions and entry code must not be probed */
+	/* The '__kprobes' functions and entry code must not be probed. */
 	return addr >= (unsigned long)__kprobes_text_start &&
 	       addr < (unsigned long)__kprobes_text_end;
 }
···
 	if (arch_within_kprobe_blacklist(addr))
 		return true;
 	/*
-	 * If there exists a kprobe_blacklist, verify and
-	 * fail any probe registration in the prohibited area
+	 * If 'kprobe_blacklist' is defined, check the address and
+	 * reject any probe registration in the prohibited area.
 	 */
 	list_for_each_entry(ent, &kprobe_blacklist, list) {
 		if (addr >= ent->start_addr && addr < ent->end_addr)
···
 }
 
 /*
- * If we have a symbol_name argument, look it up and add the offset field
+ * If 'symbol_name' is specified, look it up and add the 'offset'
  * to it. This way, we can specify a relative address to a symbol.
  * This returns encoded errors if it fails to look up symbol or invalid
  * combination of parameters.
···
 	return _kprobe_addr(p->addr, p->symbol_name, p->offset);
 }
 
-/* Check passed kprobe is valid and return kprobe in kprobe_table. */
+/*
+ * Check the 'p' is valid and return the aggregator kprobe
+ * at the same address.
+ */
 static struct kprobe *__get_valid_kprobe(struct kprobe *p)
 {
 	struct kprobe *ap, *list_p;
···
 	return ret;
 }
 
-int __weak arch_check_ftrace_location(struct kprobe *p)
+static int check_ftrace_location(struct kprobe *p)
 {
 	unsigned long ftrace_addr;
 
···
 {
 	int ret;
 
-	ret = arch_check_ftrace_location(p);
+	ret = check_ftrace_location(p);
 	if (ret)
 		return ret;
 	jump_label_lock();
···
 		goto out;
 	}
 
-	/* Check if are we probing a module */
+	/* Check if 'p' is probing a module. */
 	*probed_mod = __module_text_address((unsigned long) p->addr);
 	if (*probed_mod) {
 		/*
···
 		}
 
 		/*
-		 * If the module freed .init.text, we couldn't insert
+		 * If the module freed '.init.text', we couldn't insert
 		 * kprobes in there.
 		 */
 		if (within_module_init((unsigned long)p->addr, *probed_mod) &&
···
 
 	old_p = get_kprobe(p->addr);
 	if (old_p) {
-		/* Since this may unoptimize old_p, locking text_mutex. */
+		/* Since this may unoptimize 'old_p', locking 'text_mutex'. */
 		ret = register_aggr_kprobe(old_p, p);
 		goto out;
 	}
···
 }
 EXPORT_SYMBOL_GPL(register_kprobe);
 
-/* Check if all probes on the aggrprobe are disabled */
-static int aggr_kprobe_disabled(struct kprobe *ap)
+/* Check if all probes on the 'ap' are disabled. */
+static bool aggr_kprobe_disabled(struct kprobe *ap)
 {
 	struct kprobe *kp;
 
···
 	list_for_each_entry(kp, &ap->list, list)
 		if (!kprobe_disabled(kp))
 			/*
-			 * There is an active probe on the list.
-			 * We can't disable this ap.
+			 * Since there is an active probe on the list,
+			 * we can't disable this 'ap'.
 			 */
-			return 0;
+			return false;
 
-	return 1;
+	return true;
 }
 
-/* Disable one kprobe: Make sure called under kprobe_mutex is locked */
 static struct kprobe *__disable_kprobe(struct kprobe *p)
 {
 	struct kprobe *orig_p;
 	int ret;
+
+	lockdep_assert_held(&kprobe_mutex);
 
 	/* Get an original kprobe for return */
 	orig_p = __get_valid_kprobe(p);
···
 		/* Try to disarm and disable this/parent probe */
 		if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
 			/*
-			 * If kprobes_all_disarmed is set, orig_p
+			 * If 'kprobes_all_disarmed' is set, 'orig_p'
 			 * should have already been disarmed, so
 			 * skip unneed disarming process.
 			 */
···
 	.priority = 0x7fffffff /* we need to be notified first */
 };
 
-unsigned long __weak arch_deref_entry_point(void *entry)
-{
-	return (unsigned long)entry;
-}
-
 #ifdef CONFIG_KRETPROBES
 
+/* This assumes the 'tsk' is the current task or the is not running. */
+static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk,
+						  struct llist_node **cur)
+{
+	struct kretprobe_instance *ri = NULL;
+	struct llist_node *node = *cur;
+
+	if (!node)
+		node = tsk->kretprobe_instances.first;
+	else
+		node = node->next;
+
+	while (node) {
+		ri = container_of(node, struct kretprobe_instance, llist);
+		if (ri->ret_addr != kretprobe_trampoline_addr()) {
+			*cur = node;
+			return ri->ret_addr;
+		}
+		node = node->next;
+	}
+	return NULL;
+}
+NOKPROBE_SYMBOL(__kretprobe_find_ret_addr);
+
+/**
+ * kretprobe_find_ret_addr -- Find correct return address modified by kretprobe
+ * @tsk: Target task
+ * @fp: A frame pointer
+ * @cur: a storage of the loop cursor llist_node pointer for next call
+ *
+ * Find the correct return address modified by a kretprobe on @tsk in unsigned
+ * long type. If it finds the return address, this returns that address value,
+ * or this returns 0.
+ * The @tsk must be 'current' or a task which is not running. @fp is a hint
+ * to get the currect return address - which is compared with the
+ * kretprobe_instance::fp field. The @cur is a loop cursor for searching the
+ * kretprobe return addresses on the @tsk. The '*@cur' should be NULL at the
+ * first call, but '@cur' itself must NOT NULL.
+ */
+unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
+				      struct llist_node **cur)
+{
+	struct kretprobe_instance *ri = NULL;
+	kprobe_opcode_t *ret;
+
+	if (WARN_ON_ONCE(!cur))
+		return 0;
+
+	do {
+		ret = __kretprobe_find_ret_addr(tsk, cur);
+		if (!ret)
+			break;
+		ri = container_of(*cur, struct kretprobe_instance, llist);
+	} while (ri->fp != fp);
+
+	return (unsigned long)ret;
+}
+NOKPROBE_SYMBOL(kretprobe_find_ret_addr);
+
+void __weak arch_kretprobe_fixup_return(struct pt_regs *regs,
+					kprobe_opcode_t *correct_ret_addr)
+{
+	/*
+	 * Do nothing by default. Please fill this to update the fake return
+	 * address on the stack with the correct one on each arch if possible.
+	 */
+}
+
 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
-					     void *trampoline_address,
 					     void *frame_pointer)
 {
 	kprobe_opcode_t *correct_ret_addr = NULL;
 	struct kretprobe_instance *ri = NULL;
-	struct llist_node *first, *node;
+	struct llist_node *first, *node = NULL;
 	struct kretprobe *rp;
 
-	/* Find all nodes for this frame. */
-	first = node = current->kretprobe_instances.first;
-	while (node) {
-		ri = container_of(node, struct kretprobe_instance, llist);
-
-		BUG_ON(ri->fp != frame_pointer);
-
-		if (ri->ret_addr != trampoline_address) {
-			correct_ret_addr = ri->ret_addr;
-			/*
-			 * This is the real return address. Any other
-			 * instances associated with this task are for
-			 * other calls deeper on the call stack
-			 */
-			goto found;
-		}
-
-		node = node->next;
+	/* Find correct address and all nodes for this frame. */
+	correct_ret_addr = __kretprobe_find_ret_addr(current, &node);
+	if (!correct_ret_addr) {
+		pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n");
+		BUG_ON(1);
 	}
-	pr_err("Oops! Kretprobe fails to find correct return address.\n");
-	BUG_ON(1);
 
-found:
-	/* Unlink all nodes for this frame. */
-	current->kretprobe_instances.first = node->next;
-	node->next = NULL;
+	/*
+	 * Set the return address as the instruction pointer, because if the
+	 * user handler calls stack_trace_save_regs() with this 'regs',
+	 * the stack trace will start from the instruction pointer.
+	 */
+	instruction_pointer_set(regs, (unsigned long)correct_ret_addr);
 
-	/* Run them..  */
+	/* Run the user handler of the nodes. */
+	first = current->kretprobe_instances.first;
 	while (first) {
 		ri = container_of(first, struct kretprobe_instance, llist);
-		first = first->next;
+
+		if (WARN_ON_ONCE(ri->fp != frame_pointer))
+			break;
 
 		rp = get_kretprobe(ri);
 		if (rp && rp->handler) {
···
 			rp->handler(ri, regs);
 			__this_cpu_write(current_kprobe, prev);
 		}
+		if (first == node)
+			break;
+
+		first = first->next;
+	}
+
+	arch_kretprobe_fixup_return(regs, correct_ret_addr);
+
+	/* Unlink all nodes for this frame. */
+	first = current->kretprobe_instances.first;
+	current->kretprobe_instances.first = node->next;
+	node->next = NULL;
+
+	/* Recycle free instances. */
+	while (first) {
+		ri = container_of(first, struct kretprobe_instance, llist);
+		first = first->next;
 
 		recycle_rp_inst(ri);
 	}
···
 	if (ret)
 		return ret;
 
-	/* If only rp->kp.addr is specified, check reregistering kprobes */
+	/* If only 'rp->kp.addr' is specified, check reregistering kprobes */
 	if (rp->kp.addr && warn_kprobe_rereg(&rp->kp))
 		return -EINVAL;
 
···
 #else /* CONFIG_KRETPROBES */
 int register_kretprobe(struct kretprobe *rp)
 {
-	return -ENOSYS;
+	return -EOPNOTSUPP;
 }
 EXPORT_SYMBOL_GPL(register_kretprobe);
 
 int register_kretprobes(struct kretprobe **rps, int num)
 {
-	return -ENOSYS;
+	return -EOPNOTSUPP;
 }
 EXPORT_SYMBOL_GPL(register_kretprobes);
 
···
 	/*
 	 * The module is going away. We should disarm the kprobe which
 	 * is using ftrace, because ftrace framework is still available at
-	 * MODULE_STATE_GOING notification.
+	 * 'MODULE_STATE_GOING' notification.
 	 */
 	if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed)
 		disarm_kprobe_ftrace(p);
···
 /* Caller must NOT call this in usual path. This is only for critical case */
 void dump_kprobe(struct kprobe *kp)
 {
-	pr_err("Dumping kprobe:\n");
-	pr_err("Name: %s\nOffset: %x\nAddress: %pS\n",
+	pr_err("Dump kprobe:\n.symbol_name = %s, .offset = %x, .addr = %pS\n",
 	       kp->symbol_name, kp->offset, kp->addr);
 }
 NOKPROBE_SYMBOL(dump_kprobe);
···
 	int ret;
 
 	for (iter = start; iter < end; iter++) {
-		entry = arch_deref_entry_point((void *)*iter);
+		entry = (unsigned long)dereference_symbol_descriptor((void *)*iter);
 		ret = kprobe_add_ksym_blacklist(entry);
 		if (ret == -EINVAL)
 			continue;
···
 			return ret;
 	}
 
-	/* Symbols in __kprobes_text are blacklisted */
+	/* Symbols in '__kprobes_text' are blacklisted */
 	ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
 					(unsigned long)__kprobes_text_end);
 	if (ret)
 		return ret;
 
-	/* Symbols in noinstr section are blacklisted */
+	/* Symbols in 'noinstr' section are blacklisted */
 	ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start,
 					(unsigned long)__noinstr_text_end);
 
···
 		return NOTIFY_DONE;
 
 	/*
-	 * When MODULE_STATE_GOING was notified, both of module .text and
-	 * .init.text sections would be freed. When MODULE_STATE_LIVE was
-	 * notified, only .init.text section would be freed. We need to
+	 * When 'MODULE_STATE_GOING' was notified, both of module '.text' and
+	 * '.init.text' sections would be freed. When 'MODULE_STATE_LIVE' was
+	 * notified, only '.init.text' section would be freed. We need to
 	 * disable kprobes which have been inserted in the sections.
 	 */
 	mutex_lock(&kprobe_mutex);
···
 				 *
 				 * Note, this will also move any optimized probes
 				 * that are pending to be removed from their
-				 * corresponding lists to the freeing_list and
+				 * corresponding lists to the 'freeing_list' and
 				 * will not be touched by the delayed
-				 * kprobe_optimizer work handler.
+				 * kprobe_optimizer() work handler.
 				 */
 				kill_kprobe(p);
 			}
···
 	.priority = 0
 };
 
-/* Markers of _kprobe_blacklist section */
-extern unsigned long __start_kprobe_blacklist[];
-extern unsigned long __stop_kprobe_blacklist[];
-
 void kprobe_free_init_mem(void)
 {
 	void *start = (void *)(&__init_begin);
···
 
 	mutex_lock(&kprobe_mutex);
 
-	/* Kill all kprobes on initmem */
+	/* Kill all kprobes on initmem because the target code has been freed. */
 	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 		head = &kprobe_table[i];
 		hlist_for_each_entry(p, head, hlist) {
···
 
 	err = populate_kprobe_blacklist(__start_kprobe_blacklist,
 					__stop_kprobe_blacklist);
-	if (err) {
-		pr_err("kprobes: failed to populate blacklist: %d\n", err);
-		pr_err("Please take care of using kprobes.\n");
-	}
+	if (err)
+		pr_err("Failed to populate blacklist (error %d), kprobes not restricted, be careful using them!\n", err);
 
 	if (kretprobe_blacklist_size) {
 		/* lookup the function address from its name */
···
 			kretprobe_blacklist[i].addr =
 				kprobe_lookup_name(kretprobe_blacklist[i].name, 0);
 			if (!kretprobe_blacklist[i].addr)
-				printk("kretprobe: lookup failed: %s\n",
+				pr_err("Failed to lookup symbol '%s' for kretprobe blacklist. Maybe the target function is removed or renamed.\n",
 				       kretprobe_blacklist[i].name);
 		}
 	}
···
 	kprobes_all_disarmed = false;
 
 #if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
-	/* Init kprobe_optinsn_slots for allocation */
+	/* Init 'kprobe_optinsn_slots' for allocation */
 	kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
 #endif
 
···
 		err = register_module_notifier(&kprobe_module_nb);
 
 	kprobes_initialized = (err == 0);
-
-	if (!err)
-		init_test_probes();
 	return err;
 }
 early_initcall(init_kprobes);
···
 		list_entry(v, struct kprobe_blacklist_entry, list);
 
 	/*
-	 * If /proc/kallsyms is not showing kernel address, we won't
+	 * If '/proc/kallsyms' is not showing kernel address, we won't
 	 * show them here either.
 	 */
 	if (!kallsyms_show_value(m->file->f_cred))
···
 	}
 
 	if (errors)
-		pr_warn("Kprobes globally enabled, but failed to arm %d out of %d probes\n",
+		pr_warn("Kprobes globally enabled, but failed to enable %d out of %d probes. Please check which kprobes are kept disabled via debugfs.\n",
 			errors, total);
 	else
 		pr_info("Kprobes globally enabled\n");
···
 	}
 
 	if (errors)
-		pr_warn("Kprobes globally disabled, but failed to disarm %d out of %d probes\n",
+		pr_warn("Kprobes globally disabled, but failed to disable %d out of %d probes. Please check which kprobes are kept enabled via debugfs.\n",
 			errors, total);
 	else
 		pr_info("Kprobes globally disabled\n");
···
 static ssize_t write_enabled_file_bool(struct file *file,
 	       const char __user *user_buf, size_t count, loff_t *ppos)
 {
-	char buf[32];
-	size_t buf_size;
-	int ret = 0;
+	bool enable;
+	int ret;
 
-	buf_size = min(count, (sizeof(buf)-1));
-	if (copy_from_user(buf, user_buf, buf_size))
-		return -EFAULT;
+	ret = kstrtobool_from_user(user_buf, count, &enable);
+	if (ret)
+		return ret;
 
-	buf[buf_size] = '\0';
-	switch (buf[0]) {
-	case 'y':
-	case 'Y':
-	case '1':
-		ret = arm_all_kprobes();
-		break;
-	case 'n':
-	case 'N':
-	case '0':
-		ret = disarm_all_kprobes();
-		break;
-	default:
-		return -EINVAL;
-	}
-
+	ret = enable ? arm_all_kprobes() : disarm_all_kprobes();
 	if (ret)
 		return ret;
 
···
 static int __init debugfs_kprobe_init(void)
 {
 	struct dentry *dir;
-	unsigned int value = 1;
 
 	dir = debugfs_create_dir("kprobes", NULL);
 
 	debugfs_create_file("list", 0400, dir, NULL, &kprobes_fops);
 
-	debugfs_create_file("enabled", 0600, dir, &value, &fops_kp);
+	debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp);
 
 	debugfs_create_file("blacklist", 0400, dir, NULL,
 			    &kprobe_blacklist_fops);

kernel/livepatch/patch.c

···
 
 	ops = container_of(fops, struct klp_ops, fops);
 
+	/*
+	 * The ftrace_test_recursion_trylock() will disable preemption,
+	 * which is required for the variant of synchronize_rcu() that is
+	 * used to allow patching functions where RCU is not watching.
+	 * See klp_synchronize_transition() for more details.
+	 */
 	bit = ftrace_test_recursion_trylock(ip, parent_ip);
 	if (WARN_ON_ONCE(bit < 0))
 		return;
-	/*
-	 * A variant of synchronize_rcu() is used to allow patching functions
-	 * where RCU is not watching, see klp_synchronize_transition().
-	 */
-	preempt_disable_notrace();
 
 	func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
 				      stack_node);
···
 	klp_arch_set_pc(fregs, (unsigned long)func->new_func);
 
 unlock:
-	preempt_enable_notrace();
 	ftrace_test_recursion_unlock(bit);
 }
 

kernel/test_kprobes.c

···
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * test_kprobes.c - simple sanity test for *probes
- *
- * Copyright IBM Corp. 2008
- */
-
-#define pr_fmt(fmt) "Kprobe smoke test: " fmt
-
-#include <linux/kernel.h>
-#include <linux/kprobes.h>
-#include <linux/random.h>
-
-#define div_factor 3
-
-static u32 rand1, preh_val, posth_val;
-static int errors, handler_errors, num_tests;
-static u32 (*target)(u32 value);
-static u32 (*target2)(u32 value);
-
-static noinline u32 kprobe_target(u32 value)
-{
-	return (value / div_factor);
-}
-
-static int kp_pre_handler(struct kprobe *p, struct pt_regs *regs)
-{
-	if (preemptible()) {
-		handler_errors++;
-		pr_err("pre-handler is preemptible\n");
-	}
-	preh_val = (rand1 / div_factor);
-	return 0;
-}
-
-static void kp_post_handler(struct kprobe *p, struct pt_regs *regs,
-		unsigned long flags)
-{
-	if (preemptible()) {
-		handler_errors++;
-		pr_err("post-handler is preemptible\n");
-	}
-	if (preh_val != (rand1 / div_factor)) {
-		handler_errors++;
-		pr_err("incorrect value in post_handler\n");
-	}
-	posth_val = preh_val + div_factor;
-}
-
-static struct kprobe kp = {
-	.symbol_name = "kprobe_target",
-	.pre_handler = kp_pre_handler,
-	.post_handler = kp_post_handler
-};
-
-static int test_kprobe(void)
-{
-	int ret;
-
-	ret = register_kprobe(&kp);
-	if (ret < 0) {
-		pr_err("register_kprobe returned %d\n", ret);
-		return ret;
-	}
-
-	ret = target(rand1);
-	unregister_kprobe(&kp);
-
-	if (preh_val == 0) {
-		pr_err("kprobe pre_handler not called\n");
-		handler_errors++;
-	}
-
-	if (posth_val == 0) {
-		pr_err("kprobe post_handler not called\n");
-		handler_errors++;
-	}
-
-	return 0;
-}
-
-static noinline u32 kprobe_target2(u32 value)
-{
-	return (value / div_factor) + 1;
-}
-
-static int kp_pre_handler2(struct kprobe *p, struct pt_regs *regs)
-{
-	preh_val = (rand1 / div_factor) + 1;
-	return 0;
-}
-
-static void kp_post_handler2(struct kprobe *p, struct pt_regs *regs,
-		unsigned long flags)
-{
-	if (preh_val != (rand1 / div_factor) + 1) {
-		handler_errors++;
-		pr_err("incorrect value in post_handler2\n");
-	}
-	posth_val = preh_val + div_factor;
-}
-
-static struct kprobe kp2 = {
-	.symbol_name = "kprobe_target2",
-	.pre_handler = kp_pre_handler2,
-	.post_handler = kp_post_handler2
-};
-
-static int test_kprobes(void)
-{
-	int ret;
-	struct kprobe *kps[2] = {&kp, &kp2};
-
-	/* addr and flags should be cleard for reusing kprobe. */
-	kp.addr = NULL;
-	kp.flags = 0;
-	ret = register_kprobes(kps, 2);
-	if (ret < 0) {
-		pr_err("register_kprobes returned %d\n", ret);
-		return ret;
-	}
-
-	preh_val = 0;
-	posth_val = 0;
-	ret = target(rand1);
-
-	if (preh_val == 0) {
-		pr_err("kprobe pre_handler not called\n");
-		handler_errors++;
-	}
-
-	if (posth_val == 0) {
-		pr_err("kprobe post_handler not called\n");
-		handler_errors++;
-	}
-
-	preh_val = 0;
-	posth_val = 0;
-	ret = target2(rand1);
-
-	if (preh_val == 0) {
-		pr_err("kprobe pre_handler2 not called\n");
-		handler_errors++;
-	}
-
-	if (posth_val == 0) {
-		pr_err("kprobe post_handler2 not called\n");
-		handler_errors++;
-	}
-
-	unregister_kprobes(kps, 2);
-	return 0;
-
-}
-
-#ifdef CONFIG_KRETPROBES
-static u32 krph_val;
-
-static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
-{
-	if (preemptible()) {
-		handler_errors++;
-		pr_err("kretprobe entry handler is preemptible\n");
-	}
-	krph_val = (rand1 / div_factor);
-	return 0;
-}
-
-static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
-{
-	unsigned long ret = regs_return_value(regs);
-
-	if (preemptible()) {
-		handler_errors++;
-		pr_err("kretprobe return handler is preemptible\n");
-	}
-	if (ret != (rand1 / div_factor)) {
-		handler_errors++;
-		pr_err("incorrect value in kretprobe handler\n");
-	}
-	if (krph_val == 0) {
-		handler_errors++;
-		pr_err("call to kretprobe entry handler failed\n");
-	}
-
-	krph_val = rand1;
-	return 0;
-}
-
-static struct kretprobe rp = {
-	.handler	= return_handler,
-	.entry_handler  = entry_handler,
-	.kp.symbol_name = "kprobe_target"
-};
-
-static int test_kretprobe(void)
-{
-	int ret;
-
-	ret = register_kretprobe(&rp);
-	if (ret < 0) {
-		pr_err("register_kretprobe returned %d\n", ret);
-		return ret;
-	}
-
-	ret = target(rand1);
-	unregister_kretprobe(&rp);
-	if (krph_val != rand1) {
-		pr_err("kretprobe handler not called\n");
-		handler_errors++;
-	}
-
-	return 0;
-}
-
-static int return_handler2(struct kretprobe_instance *ri, struct pt_regs *regs)
-{
-	unsigned long ret = regs_return_value(regs);
-
-	if (ret != (rand1 / div_factor) + 1) {
-		handler_errors++;
-		pr_err("incorrect value in kretprobe handler2\n");
-	}
-	if (krph_val == 0) {
-		handler_errors++;
-		pr_err("call to kretprobe entry handler failed\n");
-	}
-
-	krph_val = rand1;
-	return 0;
-}
-
-static struct kretprobe rp2 = {
-	.handler	= return_handler2,
-	.entry_handler  = entry_handler,
-	.kp.symbol_name = "kprobe_target2"
-};
-
-static int test_kretprobes(void)
-{
-	int ret;
-	struct kretprobe *rps[2] = {&rp, &rp2};
-
-	/* addr and flags should be cleard for reusing kprobe. */
-	rp.kp.addr = NULL;
-	rp.kp.flags = 0;
-	ret = register_kretprobes(rps, 2);
-	if (ret < 0) {
-		pr_err("register_kretprobe returned %d\n", ret);
-		return ret;
-	}
-
-	krph_val = 0;
-	ret = target(rand1);
-	if (krph_val != rand1) {
-		pr_err("kretprobe handler not called\n");
-		handler_errors++;
-	}
-
-	krph_val = 0;
-	ret = target2(rand1);
-	if (krph_val != rand1) {
-		pr_err("kretprobe handler2 not called\n");
-		handler_errors++;
-	}
-	unregister_kretprobes(rps, 2);
-	return 0;
-}
-#endif /* CONFIG_KRETPROBES */
-
-int init_test_probes(void)
-{
-	int ret;
-
-	target = kprobe_target;
-	target2 = kprobe_target2;
-
-	do {
-		rand1 = prandom_u32();
-	} while (rand1 <= div_factor);
-
-	pr_info("started\n");
-	num_tests++;
-	ret = test_kprobe();
-	if (ret < 0)
-		errors++;
-
-	num_tests++;
-	ret = test_kprobes();
-	if (ret < 0)
-		errors++;
-
-#ifdef CONFIG_KRETPROBES
-	num_tests++;
-	ret = test_kretprobe();
-	if (ret < 0)
-		errors++;
-
-	num_tests++;
-	ret = test_kretprobes();
-	if (ret < 0)
-		errors++;
-#endif /* CONFIG_KRETPROBES */
-
-	if (errors)
-		pr_err("BUG: %d out of %d tests failed\n", errors, num_tests);
-	else if (handler_errors)
-		pr_err("BUG: %d error(s) running handlers\n", handler_errors);
-	else
-		pr_info("passed successfully\n");
-
-	return 0;
-}

kernel/trace/Makefile

···
 obj-$(CONFIG_TRACING) += trace_seq.o
 obj-$(CONFIG_TRACING) += trace_stat.o
 obj-$(CONFIG_TRACING) += trace_printk.o
+obj-$(CONFIG_TRACING) += 	pid_list.o
 obj-$(CONFIG_TRACING_MAP) += tracing_map.o
 obj-$(CONFIG_PREEMPTIRQ_DELAY_TEST) += preemptirq_delay_test.o
 obj-$(CONFIG_SYNTH_EVENT_GEN_TEST) += synth_event_gen_test.o

kernel/trace/fgraph.c

···
 {
 	struct ftrace_graph_ent trace;
 
+#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
 	/*
 	 * Skip graph tracing if the return location is served by direct trampoline,
 	 * since call sequence and return addresses are unpredictable anyway.
···
 	if (ftrace_direct_func_count &&
 	    ftrace_find_rec_direct(ret - MCOUNT_INSN_SIZE))
 		return -EBUSY;
+#endif
 	trace.func = func;
 	trace.depth = ++current->curr_ret_depth;
 
···
 #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
 
 static struct ftrace_ops graph_ops = {
-	.func			= ftrace_stub,
+	.func			= ftrace_graph_func,
 	.flags			= FTRACE_OPS_FL_INITIALIZED |
 				   FTRACE_OPS_FL_PID |
-				   FTRACE_OPS_FL_STUB,
+				   FTRACE_OPS_GRAPH_STUB,
 #ifdef FTRACE_GRAPH_TRAMP_ADDR
 	.trampoline		= FTRACE_GRAPH_TRAMP_ADDR,
 	/* trampoline_size is only needed for dynamically allocated tramps */

kernel/trace/ftrace.c

···
 ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
 struct ftrace_ops global_ops;
 
-#if ARCH_SUPPORTS_FTRACE_OPS
-static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
-				 struct ftrace_ops *op, struct ftrace_regs *fregs);
-#else
-/* See comment below, where ftrace_ops_list_func is defined */
-static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
-#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
-#endif
+/* Defined by vmlinux.lds.h see the commment above arch_ftrace_ops_list_func for details */
+void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+			  struct ftrace_ops *op, struct ftrace_regs *fregs);
 
 static inline void ftrace_ops_init(struct ftrace_ops *ops)
 {
···
 	       FTRACE_PROFILE_HASH_SIZE * sizeof(struct hlist_head));
 }
 
-int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
+static int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
 {
 	struct ftrace_profile_page *pg;
 	int functions;
···
 		}
 	}
 
-	entry = tracefs_create_file("function_profile_enabled", 0644,
-				    d_tracer, NULL, &ftrace_profile_fops);
+	entry = tracefs_create_file("function_profile_enabled",
+				    TRACE_MODE_WRITE, d_tracer, NULL,
+				    &ftrace_profile_fops);
 	if (!entry)
 		pr_warn("Could not create tracefs 'function_profile_enabled' entry\n");
 }
···
 		return 0;
 
 	return entry->direct;
+}
+
+static struct ftrace_func_entry*
+ftrace_add_rec_direct(unsigned long ip, unsigned long addr,
+		      struct ftrace_hash **free_hash)
+{
+	struct ftrace_func_entry *entry;
+
+	if (ftrace_hash_empty(direct_functions) ||
+	    direct_functions->count > 2 * (1 << direct_functions->size_bits)) {
+		struct ftrace_hash *new_hash;
+		int size = ftrace_hash_empty(direct_functions) ? 0 :
+			direct_functions->count + 1;
+
+		if (size < 32)
+			size = 32;
+
+		new_hash = dup_hash(direct_functions, size);
+		if (!new_hash)
+			return NULL;
+
+		*free_hash = direct_functions;
+		direct_functions = new_hash;
+	}
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return NULL;
+
+	entry->ip = ip;
+	entry->direct = addr;
+	__add_hash_entry(direct_functions, entry);
+	return entry;
 }
 
 static void call_direct_funcs(unsigned long ip, unsigned long pip,
···
 	}
 
 	ret = -ENOMEM;
-	if (ftrace_hash_empty(direct_functions) ||
-	    direct_functions->count > 2 * (1 << direct_functions->size_bits)) {
-		struct ftrace_hash *new_hash;
-		int size = ftrace_hash_empty(direct_functions) ? 0 :
-			direct_functions->count + 1;
-
-		if (size < 32)
-			size = 32;
-
-		new_hash = dup_hash(direct_functions, size);
-		if (!new_hash)
-			goto out_unlock;
-
-		free_hash = direct_functions;
-		direct_functions = new_hash;
-	}
-
-	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
-	if (!entry)
-		goto out_unlock;
-
 	direct = ftrace_find_direct_func(addr);
 	if (!direct) {
 		direct = ftrace_alloc_direct_func(addr);
-		if (!direct) {
-			kfree(entry);
+		if (!direct)
 			goto out_unlock;
-		}
 	}
 
-	entry->ip = ip;
-	entry->direct = addr;
-	__add_hash_entry(direct_functions, entry);
+	entry = ftrace_add_rec_direct(ip, addr, &free_hash);
+	if (!entry)
+		goto out_unlock;
 
 	ret = ftrace_set_filter_ip(&direct_ops, ip, 0, 0);
 	if (ret)
···
 	return ret;
 }
 EXPORT_SYMBOL_GPL(modify_ftrace_direct);
+
+#define MULTI_FLAGS (FTRACE_OPS_FL_IPMODIFY | FTRACE_OPS_FL_DIRECT | \
+		     FTRACE_OPS_FL_SAVE_REGS)
+
+static int check_direct_multi(struct ftrace_ops *ops)
+{
+	if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED))
+		return -EINVAL;
+	if ((ops->flags & MULTI_FLAGS) != MULTI_FLAGS)
+		return -EINVAL;
+	return 0;
+}
+
+static void remove_direct_functions_hash(struct ftrace_hash *hash, unsigned long addr)
+{
+	struct ftrace_func_entry *entry, *del;
+	int size, i;
+
+	size = 1 << hash->size_bits;
+	for (i = 0; i < size; i++) {
+		hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
+			del = __ftrace_lookup_ip(direct_functions, entry->ip);
+			if (del && del->direct == addr) {
+				remove_hash_entry(direct_functions, del);
+				kfree(del);
+			}
+		}
+	}
+}
+
+/**
+ * register_ftrace_direct_multi - Call a custom trampoline directly
+ * for multiple functions registered in @ops
+ * @ops: The address of the struct ftrace_ops object
+ * @addr: The address of the trampoline to call at @ops functions
+ *
+ * This is used to connect a direct calls to @addr from the nop locations
+ * of the functions registered in @ops (with by ftrace_set_filter_ip
+ * function).
+ *
+ * The location that it calls (@addr) must be able to handle a direct call,
+ * and save the parameters of the function being traced, and restore them
+ * (or inject new ones if needed), before returning.
+ *
+ * Returns:
+ *  0 on success
+ *  -EINVAL  - The @ops object was already registered with this call or
+ *             when there are no functions in @ops object.
+ *  -EBUSY   - Another direct function is already attached (there can be only one)
+ *  -ENODEV  - @ip does not point to a ftrace nop location (or not supported)
+ *  -ENOMEM  - There was an allocation failure.
+ */
+int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+	struct ftrace_hash *hash, *free_hash = NULL;
+	struct ftrace_func_entry *entry, *new;
+	int err = -EBUSY, size, i;
+
+	if (ops->func || ops->trampoline)
+		return -EINVAL;
+	if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED))
+		return -EINVAL;
+	if (ops->flags & FTRACE_OPS_FL_ENABLED)
+		return -EINVAL;
+
+	hash = ops->func_hash->filter_hash;
+	if (ftrace_hash_empty(hash))
+		return -EINVAL;
+
+	mutex_lock(&direct_mutex);
+
+	/* Make sure requested entries are not already registered.. */
+	size = 1 << hash->size_bits;
+	for (i = 0; i < size; i++) {
+		hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
+			if (ftrace_find_rec_direct(entry->ip))
+				goto out_unlock;
+		}
+	}
+
+	/* ... and insert them to direct_functions hash. */
+	err = -ENOMEM;
+	for (i = 0; i < size; i++) {
+		hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
+			new = ftrace_add_rec_direct(entry->ip, addr, &free_hash);
+			if (!new)
+				goto out_remove;
+			entry->direct = addr;
+		}
+	}
+
+	ops->func = call_direct_funcs;
+	ops->flags = MULTI_FLAGS;
+	ops->trampoline = FTRACE_REGS_ADDR;
+
+	err = register_ftrace_function(ops);
+
+ out_remove:
+	if (err)
+		remove_direct_functions_hash(hash, addr);
+
+ out_unlock:
+	mutex_unlock(&direct_mutex);
+
+	if (free_hash) {
+		synchronize_rcu_tasks();
+		free_ftrace_hash(free_hash);
+	}
+	return err;
+}
+EXPORT_SYMBOL_GPL(register_ftrace_direct_multi);
+
+/**
+ * unregister_ftrace_direct_multi - Remove calls to custom trampoline
+ * previously registered by register_ftrace_direct_multi for @ops object.
+ * @ops: The address of the struct ftrace_ops object
+ *
+ * This is used to remove a direct calls to @addr from the nop locations
+ * of the functions registered in @ops (with by ftrace_set_filter_ip
+ * function).
+ *
+ * Returns:
+ *  0 on success
+ *  -EINVAL - The @ops object was not properly registered.
+ */
+int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+	struct ftrace_hash *hash = ops->func_hash->filter_hash;
+	int err;
+
+	if (check_direct_multi(ops))
+		return -EINVAL;
+	if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
+		return -EINVAL;
+
+	mutex_lock(&direct_mutex);
+	err = unregister_ftrace_function(ops);
+	remove_direct_functions_hash(hash, addr);
+	mutex_unlock(&direct_mutex);
+	return err;
+}
+EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi);
+
+/**
+ * modify_ftrace_direct_multi - Modify an existing direct 'multi' call
+ * to call something else
+ * @ops: The address of the struct ftrace_ops object
+ * @addr: The address of the new trampoline to call at @ops functions
+ *
+ * This is used to unregister currently registered direct caller and
+ * register new one @addr on functions registered in @ops object.
+ *
+ * Note there's window between ftrace_shutdown and ftrace_startup calls
+ * where there will be no callbacks called.
+ *
+ * Returns: zero on success. Non zero on error, which includes:
+ *  -EINVAL - The @ops object was not properly registered.
+ */
+int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+	struct ftrace_hash *hash;
+	struct ftrace_func_entry *entry, *iter;
+	static struct ftrace_ops tmp_ops = {
+		.func		= ftrace_stub,
+		.flags		= FTRACE_OPS_FL_STUB,
+	};
+	int i, size;
+	int err;
+
+	if (check_direct_multi(ops))
+		return -EINVAL;
+	if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
+		return -EINVAL;
+
+	mutex_lock(&direct_mutex);
+
+	/* Enable the tmp_ops to have the same functions as the direct ops */
+	ftrace_ops_init(&tmp_ops);
+	tmp_ops.func_hash = ops->func_hash;
+
+	err = register_ftrace_function(&tmp_ops);
+	if (err)
+		goto out_direct;
+
+	/*
+	 * Now the ftrace_ops_list_func() is called to do the direct callers.
+	 * We can safely change the direct functions attached to each entry.
+	 */
+	mutex_lock(&ftrace_lock);
+
+	hash = ops->func_hash->filter_hash;
+	size = 1 << hash->size_bits;
+	for (i = 0; i < size; i++) {
+		hlist_for_each_entry(iter, &hash->buckets[i], hlist) {
+			entry = __ftrace_lookup_ip(direct_functions, iter->ip);
+			if (!entry)
+				continue;
+			entry->direct = addr;
+		}
+	}
+
+	/* Removing the tmp_ops will add the updated direct callers to the functions */
+	unregister_ftrace_function(&tmp_ops);
+
+	mutex_unlock(&ftrace_lock);
+ out_direct:
+	mutex_unlock(&direct_mutex);
+	return err;
+}
+EXPORT_SYMBOL_GPL(modify_ftrace_direct_multi);
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
 
 /**
···
 				struct dentry *parent)
 {
 
-	trace_create_file("set_ftrace_filter", 0644, parent,
+	trace_create_file("set_ftrace_filter", TRACE_MODE_WRITE, parent,
 			  ops, &ftrace_filter_fops);
 
-	trace_create_file("set_ftrace_notrace", 0644, parent,
+	trace_create_file("set_ftrace_notrace", TRACE_MODE_WRITE, parent,
 			  ops, &ftrace_notrace_fops);
 }
 
···
 static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer)
 {
 
-	trace_create_file("available_filter_functions", 0444,
+	trace_create_file("available_filter_functions", TRACE_MODE_READ,
 			d_tracer, NULL, &ftrace_avail_fops);
 
-	trace_create_file("enabled_functions", 0444,
+	trace_create_file("enabled_functions", TRACE_MODE_READ,
 			d_tracer, NULL, &ftrace_enabled_fops);
 
 	ftrace_create_filter_files(&global_ops, d_tracer);
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	trace_create_file("set_graph_function", 0644, d_tracer,
+	trace_create_file("set_graph_function", TRACE_MODE_WRITE, d_tracer,
 				    NULL,
 				    &ftrace_graph_fops);
-	trace_create_file("set_graph_notrace", 0644, d_tracer,
+	trace_create_file("set_graph_notrace", TRACE_MODE_WRITE, d_tracer,
 				    NULL,
 				    &ftrace_graph_notrace_fops);
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
···
 	ftrace_free_mem(NULL, start, end);
 }
 
+int __init __weak ftrace_dyn_arch_init(void)
+{
+	return 0;
+}
+
 void __init ftrace_init(void)
 {
 	extern unsigned long __start_mcount_loc[];
···
 	struct ftrace_ops *op;
 	int bit;
 
+	/*
+	 * The ftrace_test_and_set_recursion() will disable preemption,
+	 * which is required since some of the ops may be dynamically
+	 * allocated, they must be freed after a synchronize_rcu().
+	 */
 	bit = trace_test_and_set_recursion(ip, parent_ip, TRACE_LIST_START);
 	if (bit < 0)
 		return;
-
-	/*
-	 * Some of the ops may be dynamically allocated,
-	 * they must be freed after a synchronize_rcu().
-	 */
-	preempt_disable_notrace();
 
 	do_for_each_ftrace_op(op, ftrace_ops_list) {
 		/* Stub functions don't need to be called nor tested */
···
 		}
 	} while_for_each_ftrace_op(op);
 out:
-	preempt_enable_notrace();
 	trace_clear_recursion(bit);
 }
 
···
  * Note, CONFIG_DYNAMIC_FTRACE_WITH_REGS expects a full regs to be saved.
  * An architecture can pass partial regs with ftrace_ops and still
  * set the ARCH_SUPPORTS_FTRACE_OPS.
+ *
+ * In vmlinux.lds.h, ftrace_ops_list_func() is defined to be
+ * arch_ftrace_ops_list_func.
  */
 #if ARCH_SUPPORTS_FTRACE_OPS
-static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
-				 struct ftrace_ops *op, struct ftrace_regs *fregs)
+void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+			       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	__ftrace_ops_list_func(ip, parent_ip, NULL, fregs);
 }
-NOKPROBE_SYMBOL(ftrace_ops_list_func);
 #else
-static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
+void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
 {
 	__ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
 }
-NOKPROBE_SYMBOL(ftrace_ops_no_ops);
 #endif
+NOKPROBE_SYMBOL(arch_ftrace_ops_list_func);
 
 /*
  * If there's only one function registered but it does not support
···
 	if (bit < 0)
 		return;
 
-	preempt_disable_notrace();
-
 	if (!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching())
 		op->func(ip, parent_ip, op, fregs);
 
-	preempt_enable_notrace();
 	trace_clear_recursion(bit);
 }
 NOKPROBE_SYMBOL(ftrace_ops_assist_func);
···
 	synchronize_rcu();
 
 	if ((type & TRACE_PIDS) && pid_list)
-		trace_free_pid_list(pid_list);
+		trace_pid_list_free(pid_list);
 
 	if ((type & TRACE_NO_PIDS) && no_pid_list)
-		trace_free_pid_list(no_pid_list);
+		trace_pid_list_free(no_pid_list);
 }
 
 void ftrace_clear_pids(struct trace_array *tr)
···
 
 	if (filtered_pids) {
 		synchronize_rcu();
-		trace_free_pid_list(filtered_pids);
+		trace_pid_list_free(filtered_pids);
 	} else if (pid_list && !other_pids) {
 		/* Register a probe to set whether to ignore the tracing of a task */
 		register_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr);
···
 
 void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 {
-	trace_create_file("set_ftrace_pid", 0644, d_tracer,
+	trace_create_file("set_ftrace_pid", TRACE_MODE_WRITE, d_tracer,
 			    tr, &ftrace_pid_fops);
-	trace_create_file("set_ftrace_notrace_pid", 0644, d_tracer,
-			    tr, &ftrace_no_pid_fops);
+	trace_create_file("set_ftrace_notrace_pid", TRACE_MODE_WRITE,
+			  d_tracer, tr, &ftrace_no_pid_fops);
 }
 
 void __init ftrace_init_tracefs_toplevel(struct trace_array *tr,

kernel/trace/pid_list.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 VMware Inc, Steven Rostedt <[e-mail]>
+ */
+#include <linux/spinlock.h>
+#include <linux/irq_work.h>
+#include <linux/slab.h>
+#include "trace.h"
+
+/* See pid_list.h for details */
+
+static inline union lower_chunk *get_lower_chunk(struct trace_pid_list *pid_list)
+{
+	union lower_chunk *chunk;
+
+	lockdep_assert_held(&pid_list->lock);
+
+	if (!pid_list->lower_list)
+		return NULL;
+
+	chunk = pid_list->lower_list;
+	pid_list->lower_list = chunk->next;
+	pid_list->free_lower_chunks--;
+	WARN_ON_ONCE(pid_list->free_lower_chunks < 0);
+	chunk->next = NULL;
+	/*
+	 * If a refill needs to happen, it can not happen here
+	 * as the scheduler run queue locks are held.
+	 */
+	if (pid_list->free_lower_chunks <= CHUNK_REALLOC)
+		irq_work_queue(&pid_list->refill_irqwork);
+
+	return chunk;
+}
+
+static inline union upper_chunk *get_upper_chunk(struct trace_pid_list *pid_list)
+{
+	union upper_chunk *chunk;
+
+	lockdep_assert_held(&pid_list->lock);
+
+	if (!pid_list->upper_list)
+		return NULL;
+
+	chunk = pid_list->upper_list;
+	pid_list->upper_list = chunk->next;
+	pid_list->free_upper_chunks--;
+	WARN_ON_ONCE(pid_list->free_upper_chunks < 0);
+	chunk->next = NULL;
+	/*
+	 * If a refill needs to happen, it can not happen here
+	 * as the scheduler run queue locks are held.
+	 */
+	if (pid_list->free_upper_chunks <= CHUNK_REALLOC)
+		irq_work_queue(&pid_list->refill_irqwork);
+
+	return chunk;
+}
+
+static inline void put_lower_chunk(struct trace_pid_list *pid_list,
+				   union lower_chunk *chunk)
+{
+	lockdep_assert_held(&pid_list->lock);
+
+	chunk->next = pid_list->lower_list;
+	pid_list->lower_list = chunk;
+	pid_list->free_lower_chunks++;
+}
+
+static inline void put_upper_chunk(struct trace_pid_list *pid_list,
+				   union upper_chunk *chunk)
+{
+	lockdep_assert_held(&pid_list->lock);
+
+	chunk->next = pid_list->upper_list;
+	pid_list->upper_list = chunk;
+	pid_list->free_upper_chunks++;
+}
+
+static inline bool upper_empty(union upper_chunk *chunk)
+{
+	/*
+	 * If chunk->data has no lower chunks, it will be the same
+	 * as a zeroed bitmask. Use find_first_bit() to test it
+	 * and if it doesn't find any bits set, then the array
+	 * is empty.
+	 */
+	int bit = find_first_bit((unsigned long *)chunk->data,
+				 sizeof(chunk->data) * 8);
+	return bit >= sizeof(chunk->data) * 8;
+}
+
+static inline int pid_split(unsigned int pid, unsigned int *upper1,
+			     unsigned int *upper2, unsigned int *lower)
+{
+	/* MAX_PID should cover all pids */
+	BUILD_BUG_ON(MAX_PID < PID_MAX_LIMIT);
+
+	/* In case a bad pid is passed in, then fail */
+	if (unlikely(pid >= MAX_PID))
+		return -1;
+
+	*upper1 = (pid >> UPPER1_SHIFT) & UPPER_MASK;
+	*upper2 = (pid >> UPPER2_SHIFT) & UPPER_MASK;
+	*lower = pid & LOWER_MASK;
+
+	return 0;
+}
+
+static inline unsigned int pid_join(unsigned int upper1,
+				    unsigned int upper2, unsigned int lower)
+{
+	return ((upper1 & UPPER_MASK) << UPPER1_SHIFT) |
+		((upper2 & UPPER_MASK) << UPPER2_SHIFT) |
+		(lower & LOWER_MASK);
+}
+
+/**
+ * trace_pid_list_is_set - test if the pid is set in the list
+ * @pid_list: The pid list to test
+ * @pid: The pid to to see if set in the list.
+ *
+ * Tests if @pid is is set in the @pid_list. This is usually called
+ * from the scheduler when a task is scheduled. Its pid is checked
+ * if it should be traced or not.
+ *
+ * Return true if the pid is in the list, false otherwise.
+ */
+bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid)
+{
+	union upper_chunk *upper_chunk;
+	union lower_chunk *lower_chunk;
+	unsigned long flags;
+	unsigned int upper1;
+	unsigned int upper2;
+	unsigned int lower;
+	bool ret = false;
+
+	if (!pid_list)
+		return false;
+
+	if (pid_split(pid, &upper1, &upper2, &lower) < 0)
+		return false;
+
+	raw_spin_lock_irqsave(&pid_list->lock, flags);
+	upper_chunk = pid_list->upper[upper1];
+	if (upper_chunk) {
+		lower_chunk = upper_chunk->data[upper2];
+		if (lower_chunk)
+			ret = test_bit(lower, lower_chunk->data);
+	}
+	raw_spin_unlock_irqrestore(&pid_list->lock, flags);
+
+	return ret;
+}
+
+/**
+ * trace_pid_list_set - add a pid to the list
+ * @pid_list: The pid list to add the @pid to.
+ * @pid: The pid to add.
+ *
+ * Adds @pid to @pid_list. This is usually done explicitly by a user
+ * adding a task to be traced, or indirectly by the fork function
+ * when children should be traced and a task's pid is in the list.
+ *
+ * Return 0 on success, negative otherwise.
+ */
+int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid)
+{
+	union upper_chunk *upper_chunk;
+	union lower_chunk *lower_chunk;
+	unsigned long flags;
+	unsigned int upper1;
+	unsigned int upper2;
+	unsigned int lower;
+	int ret;
+
+	if (!pid_list)
+		return -ENODEV;
+
+	if (pid_split(pid, &upper1, &upper2, &lower) < 0)
+		return -EINVAL;
+
+	raw_spin_lock_irqsave(&pid_list->lock, flags);
+	upper_chunk = pid_list->upper[upper1];
+	if (!upper_chunk) {
+		upper_chunk = get_upper_chunk(pid_list);
+		if (!upper_chunk) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		pid_list->upper[upper1] = upper_chunk;
+	}
+	lower_chunk = upper_chunk->data[upper2];
+	if (!lower_chunk) {
+		lower_chunk = get_lower_chunk(pid_list);
+		if (!lower_chunk) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		upper_chunk->data[upper2] = lower_chunk;
+	}
+	set_bit(lower, lower_chunk->data);
+	ret = 0;
+ out:
+	raw_spin_unlock_irqrestore(&pid_list->lock, flags);
+	return ret;
+}
+
+/**
+ * trace_pid_list_clear - remove a pid from the list
+ * @pid_list: The pid list to remove the @pid from.
+ * @pid: The pid to remove.
+ *
+ * Removes @pid from @pid_list. This is usually done explicitly by a user
+ * removing tasks from tracing, or indirectly by the exit function
+ * when a task that is set to be traced exits.
+ *
+ * Return 0 on success, negative otherwise.
+ */
+int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid)
+{
+	union upper_chunk *upper_chunk;
+	union lower_chunk *lower_chunk;
+	unsigned long flags;
+	unsigned int upper1;
+	unsigned int upper2;
+	unsigned int lower;
+
+	if (!pid_list)
+		return -ENODEV;
+
+	if (pid_split(pid, &upper1, &upper2, &lower) < 0)
+		return -EINVAL;
+
+	raw_spin_lock_irqsave(&pid_list->lock, flags);
+	upper_chunk = pid_list->upper[upper1];
+	if (!upper_chunk)
+		goto out;
+
+	lower_chunk = upper_chunk->data[upper2];
+	if (!lower_chunk)
+		goto out;
+
+	clear_bit(lower, lower_chunk->data);
+
+	/* if there's no more bits set, add it to the free list */
+	if (find_first_bit(lower_chunk->data, LOWER_MAX) >= LOWER_MAX) {
+		put_lower_chunk(pid_list, lower_chunk);
+		upper_chunk->data[upper2] = NULL;
+		if (upper_empty(upper_chunk)) {
+			put_upper_chunk(pid_list, upper_chunk);
+			pid_list->upper[upper1] = NULL;
+		}
+	}
+ out:
+	raw_spin_unlock_irqrestore(&pid_list->lock, flags);
+	return 0;
+}
+
+/**
+ * trace_pid_list_next - return the next pid in the list
+ * @pid_list: The pid list to examine.
+ * @pid: The pid to start from
+ * @next: The pointer to place the pid that is set starting from @pid.
+ *
+ * Looks for the next consecutive pid that is in @pid_list starting
+ * at the pid specified by @pid. If one is set (including @pid), then
+ * that pid is placed into @next.
+ *
+ * Return 0 when a pid is found, -1 if there are no more pids included.
+ */
+int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid,
+			unsigned int *next)
+{
+	union upper_chunk *upper_chunk;
+	union lower_chunk *lower_chunk;
+	unsigned long flags;
+	unsigned int upper1;
+	unsigned int upper2;
+	unsigned int lower;
+
+	if (!pid_list)
+		return -ENODEV;
+
+	if (pid_split(pid, &upper1, &upper2, &lower) < 0)
+		return -EINVAL;
+
+	raw_spin_lock_irqsave(&pid_list->lock, flags);
+	for (; upper1 <= UPPER_MASK; upper1++, upper2 = 0) {
+		upper_chunk = pid_list->upper[upper1];
+
+		if (!upper_chunk)
+			continue;
+
+		for (; upper2 <= UPPER_MASK; upper2++, lower = 0) {
+			lower_chunk = upper_chunk->data[upper2];
+			if (!lower_chunk)
+				continue;
+
+			lower = find_next_bit(lower_chunk->data, LOWER_MAX,
+					    lower);
+			if (lower < LOWER_MAX)
+				goto found;
+		}
+	}
+
+ found:
+	raw_spin_unlock_irqrestore(&pid_list->lock, flags);
+	if (upper1 > UPPER_MASK)
+		return -1;
+
+	*next = pid_join(upper1, upper2, lower);
+	return 0;
+}
+
+/**
+ * trace_pid_list_first - return the first pid in the list
+ * @pid_list: The pid list to examine.
+ * @pid: The pointer to place the pid first found pid that is set.
+ *
+ * Looks for the first pid that is set in @pid_list, and places it
+ * into @pid if found.
+ *
+ * Return 0 when a pid is found, -1 if there are no pids set.
+ */
+int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid)
+{
+	return trace_pid_list_next(pid_list, 0, pid);
+}
+
+static void pid_list_refill_irq(struct irq_work *iwork)
+{
+	struct trace_pid_list *pid_list = container_of(iwork, struct trace_pid_list,
+						       refill_irqwork);
+	union upper_chunk *upper = NULL;
+	union lower_chunk *lower = NULL;
+	union upper_chunk **upper_next = &upper;
+	union lower_chunk **lower_next = &lower;
+	int upper_count;
+	int lower_count;
+	int ucnt = 0;
+	int lcnt = 0;
+
+ again:
+	raw_spin_lock(&pid_list->lock);
+	upper_count = CHUNK_ALLOC - pid_list->free_upper_chunks;
+	lower_count = CHUNK_ALLOC - pid_list->free_lower_chunks;
+	raw_spin_unlock(&pid_list->lock);
+
+	if (upper_count <= 0 && lower_count <= 0)
+		return;
+
+	while (upper_count-- > 0) {
+		union upper_chunk *chunk;
+
+		chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+		if (!chunk)
+			break;
+		*upper_next = chunk;
+		upper_next = &chunk->next;
+		ucnt++;
+	}
+
+	while (lower_count-- > 0) {
+		union lower_chunk *chunk;
+
+		chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+		if (!chunk)
+			break;
+		*lower_next = chunk;
+		lower_next = &chunk->next;
+		lcnt++;
+	}
+
+	raw_spin_lock(&pid_list->lock);
+	if (upper) {
+		*upper_next = pid_list->upper_list;
+		pid_list->upper_list = upper;
+		pid_list->free_upper_chunks += ucnt;
+	}
+	if (lower) {
+		*lower_next = pid_list->lower_list;
+		pid_list->lower_list = lower;
+		pid_list->free_lower_chunks += lcnt;
+	}
+	raw_spin_unlock(&pid_list->lock);
+
+	/*
+	 * On success of allocating all the chunks, both counters
+	 * will be less than zero. If they are not, then an allocation
+	 * failed, and we should not try again.
+	 */
+	if (upper_count >= 0 || lower_count >= 0)
+		return;
+	/*
+	 * When the locks were released, free chunks could have
+	 * been used and allocation needs to be done again. Might as
+	 * well allocate it now.
+	 */
+	goto again;
+}
+
+/**
+ * trace_pid_list_alloc - create a new pid_list
+ *
+ * Allocates a new pid_list to store pids into.
+ *
+ * Returns the pid_list on success, NULL otherwise.
+ */
+struct trace_pid_list *trace_pid_list_alloc(void)
+{
+	struct trace_pid_list *pid_list;
+	int i;
+
+	/* According to linux/thread.h, pids can be no bigger that 30 bits */
+	WARN_ON_ONCE(pid_max > (1 << 30));
+
+	pid_list = kzalloc(sizeof(*pid_list), GFP_KERNEL);
+	if (!pid_list)
+		return NULL;
+
+	init_irq_work(&pid_list->refill_irqwork, pid_list_refill_irq);
+
+	raw_spin_lock_init(&pid_list->lock);
+
+	for (i = 0; i < CHUNK_ALLOC; i++) {
+		union upper_chunk *chunk;
+
+		chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+		if (!chunk)
+			break;
+		chunk->next = pid_list->upper_list;
+		pid_list->upper_list = chunk;
+		pid_list->free_upper_chunks++;
+	}
+
+	for (i = 0; i < CHUNK_ALLOC; i++) {
+		union lower_chunk *chunk;
+
+		chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+		if (!chunk)
+			break;
+		chunk->next = pid_list->lower_list;
+		pid_list->lower_list = chunk;
+		pid_list->free_lower_chunks++;
+	}
+
+	return pid_list;
+}
+
+/**
+ * trace_pid_list_free - Frees an allocated pid_list.
+ *
+ * Frees the memory for a pid_list that was allocated.
+ */
+void trace_pid_list_free(struct trace_pid_list *pid_list)
+{
+	union upper_chunk *upper;
+	union lower_chunk *lower;
+	int i, j;
+
+	if (!pid_list)
+		return;
+
+	irq_work_sync(&pid_list->refill_irqwork);
+
+	while (pid_list->lower_list) {
+		union lower_chunk *chunk;
+
+		chunk = pid_list->lower_list;
+		pid_list->lower_list = pid_list->lower_list->next;
+		kfree(chunk);
+	}
+
+	while (pid_list->upper_list) {
+		union upper_chunk *chunk;
+
+		chunk = pid_list->upper_list;
+		pid_list->upper_list = pid_list->upper_list->next;
+		kfree(chunk);
+	}
+
+	for (i = 0; i < UPPER1_SIZE; i++) {
+		upper = pid_list->upper[i];
+		if (upper) {
+			for (j = 0; j < UPPER2_SIZE; j++) {
+				lower = upper->data[j];
+				kfree(lower);
+			}
+			kfree(upper);
+		}
+	}
+	kfree(pid_list);
+}

kernel/trace/pid_list.h

···
+// SPDX-License-Identifier: GPL-2.0
+
+/* Do not include this file directly. */
+
+#ifndef _TRACE_INTERNAL_PID_LIST_H
+#define _TRACE_INTERNAL_PID_LIST_H
+
+/*
+ * In order to keep track of what pids to trace, a tree is created much
+ * like page tables are used. This creates a sparse bit map, where
+ * the tree is filled in when needed. A PID is at most 30 bits (see
+ * linux/thread.h), and is broken up into 3 sections based on the bit map
+ * of the bits. The 8 MSB is the "upper1" section. The next 8 MSB is the
+ * "upper2" section and the 14 LSB is the "lower" section.
+ *
+ * A trace_pid_list structure holds the "upper1" section, in an
+ * array of 256 pointers (1 or 2K in size) to "upper_chunk" unions, where
+ * each has an array of 256 pointers (1 or 2K in size) to the "lower_chunk"
+ * structures, where each has an array of size 2K bytes representing a bitmask
+ * of the 14 LSB of the PID (256 * 8 = 2048)
+ *
+ * When a trace_pid_list is allocated, it includes the 256 pointer array
+ * of the upper1 unions. Then a "cache" of upper and lower is allocated
+ * where these will be assigned as needed.
+ *
+ * When a bit is set in the pid_list bitmask, the pid to use has
+ * the 8 MSB masked, and this is used to index the array in the
+ * pid_list to find the next upper union. If the element is NULL,
+ * then one is retrieved from the upper_list cache. If none is
+ * available, then -ENOMEM is returned.
+ *
+ * The next 8 MSB is used to index into the "upper2" section. If this
+ * element is NULL, then it is retrieved from the lower_list cache.
+ * Again, if one is not available -ENOMEM is returned.
+ *
+ * Finally the 14 LSB of the PID is used to set the bit in the 16384
+ * bitmask (made up of 2K bytes).
+ *
+ * When the second upper section or the lower section has their last
+ * bit cleared, they are added back to the free list to be reused
+ * when needed.
+ */
+
+#define UPPER_BITS	8
+#define UPPER_MAX	(1 << UPPER_BITS)
+#define UPPER1_SIZE	(1 << UPPER_BITS)
+#define UPPER2_SIZE	(1 << UPPER_BITS)
+
+#define LOWER_BITS	14
+#define LOWER_MAX	(1 << LOWER_BITS)
+#define LOWER_SIZE	(LOWER_MAX / BITS_PER_LONG)
+
+#define UPPER1_SHIFT	(LOWER_BITS + UPPER_BITS)
+#define UPPER2_SHIFT	LOWER_BITS
+#define LOWER_MASK	(LOWER_MAX - 1)
+
+#define UPPER_MASK	(UPPER_MAX - 1)
+
+/* According to linux/thread.h pids can not be bigger than or equal to 1 << 30 */
+#define MAX_PID		(1 << 30)
+
+/* Just keep 6 chunks of both upper and lower in the cache on alloc */
+#define CHUNK_ALLOC 6
+
+/* Have 2 chunks free, trigger a refill of the cache */
+#define CHUNK_REALLOC 2
+
+union lower_chunk {
+	union lower_chunk		*next;
+	unsigned long			data[LOWER_SIZE]; // 2K in size
+};
+
+union upper_chunk {
+	union upper_chunk		*next;
+	union lower_chunk		*data[UPPER2_SIZE]; // 1 or 2K in size
+};
+
+struct trace_pid_list {
+	raw_spinlock_t			lock;
+	struct irq_work			refill_irqwork;
+	union upper_chunk		*upper[UPPER1_SIZE]; // 1 or 2K in size
+	union upper_chunk		*upper_list;
+	union lower_chunk		*lower_list;
+	int				free_upper_chunks;
+	int				free_lower_chunks;
+};
+
+#endif /* _TRACE_INTERNAL_PID_LIST_H */

kernel/trace/ring_buffer.c

···
 trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
 {
 	unsigned int val = cpu_buffer->current_context;
-	unsigned long pc = preempt_count();
-	int bit;
+	int bit = interrupt_context_level();
 
-	if (!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
-		bit = RB_CTX_NORMAL;
-	else
-		bit = pc & NMI_MASK ? RB_CTX_NMI :
-			pc & HARDIRQ_MASK ? RB_CTX_IRQ : RB_CTX_SOFTIRQ;
+	bit = RB_CTX_NORMAL - bit;
 
 	if (unlikely(val & (1 << (bit + cpu_buffer->nest)))) {
 		/*

kernel/trace/trace.c

···
 	return 0;
 }
 
-void trace_free_pid_list(struct trace_pid_list *pid_list)
-{
-	vfree(pid_list->pids);
-	kfree(pid_list);
-}
-
 /**
  * trace_find_filtered_pid - check if a pid exists in a filtered_pid list
  * @filtered_pids: The list of pids to check
···
 bool
 trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid)
 {
-	/*
-	 * If pid_max changed after filtered_pids was created, we
-	 * by default ignore all pids greater than the previous pid_max.
-	 */
-	if (search_pid >= filtered_pids->pid_max)
-		return false;
-
-	return test_bit(search_pid, filtered_pids->pids);
+	return trace_pid_list_is_set(filtered_pids, search_pid);
 }
 
 /**
···
 			return;
 	}
 
-	/* Sorry, but we don't support pid_max changing after setting */
-	if (task->pid >= pid_list->pid_max)
-		return;
-
 	/* "self" is set for forks, and NULL for exits */
 	if (self)
-		set_bit(task->pid, pid_list->pids);
+		trace_pid_list_set(pid_list, task->pid);
 	else
-		clear_bit(task->pid, pid_list->pids);
+		trace_pid_list_clear(pid_list, task->pid);
 }
 
 /**
···
  */
 void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos)
 {
-	unsigned long pid = (unsigned long)v;
+	long pid = (unsigned long)v;
+	unsigned int next;
 
 	(*pos)++;
 
 	/* pid already is +1 of the actual previous bit */
-	pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid);
+	if (trace_pid_list_next(pid_list, pid, &next) < 0)
+		return NULL;
+
+	pid = next;
 
 	/* Return pid + 1 to allow zero to be represented */
-	if (pid < pid_list->pid_max)
-		return (void *)(pid + 1);
-
-	return NULL;
+	return (void *)(pid + 1);
 }
 
 /**
···
 void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos)
 {
 	unsigned long pid;
+	unsigned int first;
 	loff_t l = 0;
 
-	pid = find_first_bit(pid_list->pids, pid_list->pid_max);
-	if (pid >= pid_list->pid_max)
+	if (trace_pid_list_first(pid_list, &first) < 0)
 		return NULL;
+
+	pid = first;
 
 	/* Return pid + 1 so that zero can be the exit value */
 	for (pid++; pid && l < *pos;
···
 	unsigned long val;
 	int nr_pids = 0;
 	ssize_t read = 0;
-	ssize_t ret = 0;
+	ssize_t ret;
 	loff_t pos;
 	pid_t pid;
 
···
 	 * the user. If the operation fails, then the current list is
 	 * not modified.
 	 */
-	pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL);
+	pid_list = trace_pid_list_alloc();
 	if (!pid_list) {
 		trace_parser_put(&parser);
 		return -ENOMEM;
 	}
 
-	pid_list->pid_max = READ_ONCE(pid_max);
-
-	/* Only truncating will shrink pid_max */
-	if (filtered_pids && filtered_pids->pid_max > pid_list->pid_max)
-		pid_list->pid_max = filtered_pids->pid_max;
-
-	pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3);
-	if (!pid_list->pids) {
-		trace_parser_put(&parser);
-		kfree(pid_list);
-		return -ENOMEM;
-	}
-
 	if (filtered_pids) {
 		/* copy the current bits to the new max */
-		for_each_set_bit(pid, filtered_pids->pids,
-				 filtered_pids->pid_max) {
-			set_bit(pid, pid_list->pids);
+		ret = trace_pid_list_first(filtered_pids, &pid);
+		while (!ret) {
+			trace_pid_list_set(pid_list, pid);
+			ret = trace_pid_list_next(filtered_pids, pid + 1, &pid);
 			nr_pids++;
 		}
 	}
 
+	ret = 0;
 	while (cnt > 0) {
 
 		pos = 0;
···
 		ret = -EINVAL;
 		if (kstrtoul(parser.buffer, 0, &val))
 			break;
-		if (val >= pid_list->pid_max)
-			break;
 
 		pid = (pid_t)val;
 
-		set_bit(pid, pid_list->pids);
+		if (trace_pid_list_set(pid_list, pid) < 0) {
+			ret = -1;
+			break;
+		}
 		nr_pids++;
 
 		trace_parser_clear(&parser);
···
 	trace_parser_put(&parser);
 
 	if (ret < 0) {
-		trace_free_pid_list(pid_list);
+		trace_pid_list_free(pid_list);
 		return ret;
 	}
 
 	if (!nr_pids) {
 		/* Cleared the list of pids */
-		trace_free_pid_list(pid_list);
+		trace_pid_list_free(pid_list);
 		read = ret;
 		pid_list = NULL;
 	}
···
 {
 	INIT_WORK(&tr->fsnotify_work, latency_fsnotify_workfn);
 	init_irq_work(&tr->fsnotify_irqwork, latency_fsnotify_workfn_irq);
-	tr->d_max_latency = trace_create_file("tracing_max_latency", 0644,
+	tr->d_max_latency = trace_create_file("tracing_max_latency",
+					      TRACE_MODE_WRITE,
 					      d_tracer, &tr->max_latency,
 					      &tracing_max_lat_fops);
 }
···
 	|| defined(CONFIG_OSNOISE_TRACER)
 
 #define trace_create_maxlat_file(tr, d_tracer)				\
-	trace_create_file("tracing_max_latency", 0644, d_tracer,	\
-			  &tr->max_latency, &tracing_max_lat_fops)
+	trace_create_file("tracing_max_latency", TRACE_MODE_WRITE,	\
+			  d_tracer, &tr->max_latency, &tracing_max_lat_fops)
 
 #else
 #define trace_create_maxlat_file(tr, d_tracer)	 do { } while (0)
···
 
 static void trace_create_eval_file(struct dentry *d_tracer)
 {
-	trace_create_file("eval_map", 0444, d_tracer,
+	trace_create_file("eval_map", TRACE_MODE_READ, d_tracer,
 			  NULL, &tracing_eval_map_fops);
 }
 
···
 	}
 
 	/* per cpu trace_pipe */
-	trace_create_cpu_file("trace_pipe", 0444, d_cpu,
+	trace_create_cpu_file("trace_pipe", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_pipe_fops);
 
 	/* per cpu trace */
-	trace_create_cpu_file("trace", 0644, d_cpu,
+	trace_create_cpu_file("trace", TRACE_MODE_WRITE, d_cpu,
 				tr, cpu, &tracing_fops);
 
-	trace_create_cpu_file("trace_pipe_raw", 0444, d_cpu,
+	trace_create_cpu_file("trace_pipe_raw", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_buffers_fops);
 
-	trace_create_cpu_file("stats", 0444, d_cpu,
+	trace_create_cpu_file("stats", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_stats_fops);
 
-	trace_create_cpu_file("buffer_size_kb", 0444, d_cpu,
+	trace_create_cpu_file("buffer_size_kb", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_entries_fops);
 
 #ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_cpu_file("snapshot", 0644, d_cpu,
+	trace_create_cpu_file("snapshot", TRACE_MODE_WRITE, d_cpu,
 				tr, cpu, &snapshot_fops);
 
-	trace_create_cpu_file("snapshot_raw", 0444, d_cpu,
+	trace_create_cpu_file("snapshot_raw", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &snapshot_raw_fops);
 #endif
 }
···
 	topt->opt = opt;
 	topt->tr = tr;
 
-	topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
-				    &trace_options_fops);
+	topt->entry = trace_create_file(opt->name, TRACE_MODE_WRITE,
+					t_options, topt, &trace_options_fops);
 
 }
 
···
 	if (!t_options)
 		return NULL;
 
-	return trace_create_file(option, 0644, t_options,
+	return trace_create_file(option, TRACE_MODE_WRITE, t_options,
 				 (void *)&tr->trace_flags_index[index],
 				 &trace_options_core_fops);
 }
···
 	struct trace_event_file *file;
 	int cpu;
 
-	trace_create_file("available_tracers", 0444, d_tracer,
+	trace_create_file("available_tracers", TRACE_MODE_READ, d_tracer,
 			tr, &show_traces_fops);
 
-	trace_create_file("current_tracer", 0644, d_tracer,
+	trace_create_file("current_tracer", TRACE_MODE_WRITE, d_tracer,
 			tr, &set_tracer_fops);
 
-	trace_create_file("tracing_cpumask", 0644, d_tracer,
+	trace_create_file("tracing_cpumask", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_cpumask_fops);
 
-	trace_create_file("trace_options", 0644, d_tracer,
+	trace_create_file("trace_options", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_iter_fops);
 
-	trace_create_file("trace", 0644, d_tracer,
+	trace_create_file("trace", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_fops);
 
-	trace_create_file("trace_pipe", 0444, d_tracer,
+	trace_create_file("trace_pipe", TRACE_MODE_READ, d_tracer,
 			  tr, &tracing_pipe_fops);
 
-	trace_create_file("buffer_size_kb", 0644, d_tracer,
+	trace_create_file("buffer_size_kb", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_entries_fops);
 
-	trace_create_file("buffer_total_size_kb", 0444, d_tracer,
+	trace_create_file("buffer_total_size_kb", TRACE_MODE_READ, d_tracer,
 			  tr, &tracing_total_entries_fops);
 
 	trace_create_file("free_buffer", 0200, d_tracer,
···
 
 	file = __find_event_file(tr, "ftrace", "print");
 	if (file && file->dir)
-		trace_create_file("trigger", 0644, file->dir, file,
-				  &event_trigger_fops);
+		trace_create_file("trigger", TRACE_MODE_WRITE, file->dir,
+				  file, &event_trigger_fops);
 	tr->trace_marker_file = file;
 
 	trace_create_file("trace_marker_raw", 0220, d_tracer,
 			  tr, &tracing_mark_raw_fops);
 
-	trace_create_file("trace_clock", 0644, d_tracer, tr,
+	trace_create_file("trace_clock", TRACE_MODE_WRITE, d_tracer, tr,
 			  &trace_clock_fops);
 
-	trace_create_file("tracing_on", 0644, d_tracer,
+	trace_create_file("tracing_on", TRACE_MODE_WRITE, d_tracer,
 			  tr, &rb_simple_fops);
 
-	trace_create_file("timestamp_mode", 0444, d_tracer, tr,
+	trace_create_file("timestamp_mode", TRACE_MODE_READ, d_tracer, tr,
 			  &trace_time_stamp_mode_fops);
 
 	tr->buffer_percent = 50;
 
-	trace_create_file("buffer_percent", 0444, d_tracer,
+	trace_create_file("buffer_percent", TRACE_MODE_READ, d_tracer,
 			tr, &buffer_percent_fops);
 
 	create_trace_options_dir(tr);
···
 		MEM_FAIL(1, "Could not allocate function filter files");
 
 #ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_file("snapshot", 0644, d_tracer,
+	trace_create_file("snapshot", TRACE_MODE_WRITE, d_tracer,
 			  tr, &snapshot_fops);
 #endif
 
-	trace_create_file("error_log", 0644, d_tracer,
+	trace_create_file("error_log", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_err_log_fops);
 
 	for_each_tracing_cpu(cpu)
···
 	init_tracer_tracefs(&global_trace, NULL);
 	ftrace_init_tracefs_toplevel(&global_trace, NULL);
 
-	trace_create_file("tracing_thresh", 0644, NULL,
+	trace_create_file("tracing_thresh", TRACE_MODE_WRITE, NULL,
 			&global_trace, &tracing_thresh_fops);
 
-	trace_create_file("README", 0444, NULL,
+	trace_create_file("README", TRACE_MODE_READ, NULL,
 			NULL, &tracing_readme_fops);
 
-	trace_create_file("saved_cmdlines", 0444, NULL,
+	trace_create_file("saved_cmdlines", TRACE_MODE_READ, NULL,
 			NULL, &tracing_saved_cmdlines_fops);
 
-	trace_create_file("saved_cmdlines_size", 0644, NULL,
+	trace_create_file("saved_cmdlines_size", TRACE_MODE_WRITE, NULL,
 			  NULL, &tracing_saved_cmdlines_size_fops);
 
-	trace_create_file("saved_tgids", 0444, NULL,
+	trace_create_file("saved_tgids", TRACE_MODE_READ, NULL,
 			NULL, &tracing_saved_tgids_fops);
 
 	trace_eval_init();
···
 #endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-	trace_create_file("dyn_ftrace_total_info", 0444, NULL,
+	trace_create_file("dyn_ftrace_total_info", TRACE_MODE_READ, NULL,
 			NULL, &tracing_dyn_info_fops);
 #endif
 

kernel/trace/trace.h

···
 #include <linux/ctype.h>
 #include <linux/once_lite.h>
 
+#include "pid_list.h"
+
 #ifdef CONFIG_FTRACE_SYSCALLS
 #include <asm/unistd.h>		/* For NR_SYSCALLS	     */
 #include <asm/syscall.h>	/* some archs define it here */
 #endif
+
+#define TRACE_MODE_WRITE	0640
+#define TRACE_MODE_READ		0440
 
 enum trace_type {
 	__TRACE_FIRST_TYPE = 0,
···
 	struct trace_option_dentry	*topts;
 };
 
-struct trace_pid_list {
-	int				pid_max;
-	unsigned long			*pids;
-};
+struct trace_pid_list *trace_pid_list_alloc(void);
+void trace_pid_list_free(struct trace_pid_list *pid_list);
+bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid);
+int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid);
+int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid);
+int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid);
+int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid,
+			unsigned int *next);
 
 enum {
 	TRACE_PIDS		= BIT(0),
···
 		 * is set, and called by an interrupt handler, we still
 		 * want to trace it.
 		 */
-		if (in_irq())
+		if (in_hardirq())
 			trace_recursion_set(TRACE_IRQ_BIT);
 		else
 			trace_recursion_clear(TRACE_IRQ_BIT);

kernel/trace/trace_boot.c

···
 		/* All digit started node should be instances. */
 		if (trace_boot_compose_hist_cmd(node, buf, size) == 0) {
 			tmp = kstrdup(buf, GFP_KERNEL);
+			if (!tmp)
+				return;
 			if (trigger_process_regex(file, buf) < 0)
 				pr_err("Failed to apply hist trigger: %s\n", tmp);
 			kfree(tmp);
···
 	if (xbc_node_find_subkey(hnode, "keys")) {
 		if (trace_boot_compose_hist_cmd(hnode, buf, size) == 0) {
 			tmp = kstrdup(buf, GFP_KERNEL);
+			if (!tmp)
+				return;
 			if (trigger_process_regex(file, buf) < 0)
 				pr_err("Failed to apply hist trigger: %s\n", tmp);
 			kfree(tmp);

kernel/trace/trace_dynevent.c

···
 	if (ret)
 		return 0;
 
-	entry = tracefs_create_file("dynamic_events", 0644, NULL,
+	entry = tracefs_create_file("dynamic_events", TRACE_MODE_WRITE, NULL,
 				    NULL, &dynamic_events_ops);
 
 	/* Event list interface */

kernel/trace/trace_event_perf.c

···
 	BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
 
 	if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-		      "perf buffer not large enough"))
+		      "perf buffer not large enough, wanted %d, have %d",
+		      size, PERF_MAX_TRACE_SIZE))
 		return NULL;
 
 	*rctxp = rctx = perf_swevent_get_recursion_context();
···
 	if (!rcu_is_watching())
 		return;
 
-	if ((unsigned long)ops->private != smp_processor_id())
-		return;
-
 	bit = ftrace_test_recursion_trylock(ip, parent_ip);
 	if (bit < 0)
 		return;
+
+	if ((unsigned long)ops->private != smp_processor_id())
+		goto out;
 
 	event = container_of(ops, struct perf_event, ftrace_ops);
 

kernel/trace/trace_events.c

···
 	tracepoint_synchronize_unregister();
 
 	if ((type & TRACE_PIDS) && pid_list)
-		trace_free_pid_list(pid_list);
+		trace_pid_list_free(pid_list);
 
 	if ((type & TRACE_NO_PIDS) && no_pid_list)
-		trace_free_pid_list(no_pid_list);
+		trace_pid_list_free(no_pid_list);
 }
 
 static void ftrace_clear_event_pids(struct trace_array *tr, int type)
···
 
 	if (filtered_pids) {
 		tracepoint_synchronize_unregister();
-		trace_free_pid_list(filtered_pids);
+		trace_pid_list_free(filtered_pids);
 	} else if (pid_list && !other_pids) {
 		register_pid_events(tr);
 	}
···
 	/* the ftrace system is special, do not create enable or filter files */
 	if (strcmp(name, "ftrace") != 0) {
 
-		entry = tracefs_create_file("filter", 0644, dir->entry, dir,
+		entry = tracefs_create_file("filter", TRACE_MODE_WRITE,
+					    dir->entry, dir,
 					    &ftrace_subsystem_filter_fops);
 		if (!entry) {
 			kfree(system->filter);
···
 			pr_warn("Could not create tracefs '%s/filter' entry\n", name);
 		}
 
-		trace_create_file("enable", 0644, dir->entry, dir,
+		trace_create_file("enable", TRACE_MODE_WRITE, dir->entry, dir,
 				  &ftrace_system_enable_fops);
 	}
 
···
 	}
 
 	if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
-		trace_create_file("enable", 0644, file->dir, file,
+		trace_create_file("enable", TRACE_MODE_WRITE, file->dir, file,
 				  &ftrace_enable_fops);
 
 #ifdef CONFIG_PERF_EVENTS
 	if (call->event.type && call->class->reg)
-		trace_create_file("id", 0444, file->dir,
+		trace_create_file("id", TRACE_MODE_READ, file->dir,
 				  (void *)(long)call->event.type,
 				  &ftrace_event_id_fops);
 #endif
···
 	 * triggers or filters.
 	 */
 	if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)) {
-		trace_create_file("filter", 0644, file->dir, file,
-				  &ftrace_event_filter_fops);
+		trace_create_file("filter", TRACE_MODE_WRITE, file->dir,
+				  file, &ftrace_event_filter_fops);
 
-		trace_create_file("trigger", 0644, file->dir, file,
-				  &event_trigger_fops);
+		trace_create_file("trigger", TRACE_MODE_WRITE, file->dir,
+				  file, &event_trigger_fops);
 	}
 
 #ifdef CONFIG_HIST_TRIGGERS
-	trace_create_file("hist", 0444, file->dir, file,
+	trace_create_file("hist", TRACE_MODE_READ, file->dir, file,
 			  &event_hist_fops);
 #endif
 #ifdef CONFIG_HIST_TRIGGERS_DEBUG
-	trace_create_file("hist_debug", 0444, file->dir, file,
+	trace_create_file("hist_debug", TRACE_MODE_READ, file->dir, file,
 			  &event_hist_debug_fops);
 #endif
-	trace_create_file("format", 0444, file->dir, call,
+	trace_create_file("format", TRACE_MODE_READ, file->dir, call,
 			  &ftrace_event_format_fops);
 
 #ifdef CONFIG_TRACE_EVENT_INJECT
···
 	struct dentry *d_events;
 	struct dentry *entry;
 
-	entry = tracefs_create_file("set_event", 0644, parent,
+	entry = tracefs_create_file("set_event", TRACE_MODE_WRITE, parent,
 				    tr, &ftrace_set_event_fops);
 	if (!entry) {
 		pr_warn("Could not create tracefs 'set_event' entry\n");
···
 		return -ENOMEM;
 	}
 
-	entry = trace_create_file("enable", 0644, d_events,
+	entry = trace_create_file("enable", TRACE_MODE_WRITE, d_events,
 				  tr, &ftrace_tr_enable_fops);
 	if (!entry) {
 		pr_warn("Could not create tracefs 'enable' entry\n");
···
 
 	/* There are not as crucial, just warn if they are not created */
 
-	entry = tracefs_create_file("set_event_pid", 0644, parent,
+	entry = tracefs_create_file("set_event_pid", TRACE_MODE_WRITE, parent,
 				    tr, &ftrace_set_event_pid_fops);
 	if (!entry)
 		pr_warn("Could not create tracefs 'set_event_pid' entry\n");
 
-	entry = tracefs_create_file("set_event_notrace_pid", 0644, parent,
-				    tr, &ftrace_set_event_notrace_pid_fops);
+	entry = tracefs_create_file("set_event_notrace_pid",
+				    TRACE_MODE_WRITE, parent, tr,
+				    &ftrace_set_event_notrace_pid_fops);
 	if (!entry)
 		pr_warn("Could not create tracefs 'set_event_notrace_pid' entry\n");
 
 	/* ring buffer internal formats */
-	entry = trace_create_file("header_page", 0444, d_events,
+	entry = trace_create_file("header_page", TRACE_MODE_READ, d_events,
 				  ring_buffer_print_page_header,
 				  &ftrace_show_header_fops);
 	if (!entry)
 		pr_warn("Could not create tracefs 'header_page' entry\n");
 
-	entry = trace_create_file("header_event", 0444, d_events,
+	entry = trace_create_file("header_event", TRACE_MODE_READ, d_events,
 				  ring_buffer_print_entry_header,
 				  &ftrace_show_header_fops);
 	if (!entry)
···
 	if (!tr)
 		return -ENODEV;
 
-	entry = tracefs_create_file("available_events", 0444, NULL,
-				    tr, &ftrace_avail_fops);
+	entry = tracefs_create_file("available_events", TRACE_MODE_READ,
+				    NULL, tr, &ftrace_avail_fops);
 	if (!entry)
 		pr_warn("Could not create tracefs 'available_events' entry\n");
 

kernel/trace/trace_events_hist.c

···
 	C(EMPTY_SORT_FIELD,	"Empty sort field"),			\
 	C(TOO_MANY_SORT_FIELDS,	"Too many sort fields (Max = 2)"),	\
 	C(INVALID_SORT_FIELD,	"Sort field must be a key or a val"),	\
-	C(INVALID_STR_OPERAND,	"String type can not be an operand in expression"),
+	C(INVALID_STR_OPERAND,	"String type can not be an operand in expression"), \
+	C(EXPECT_NUMBER,	"Expecting numeric literal"),		\
+	C(UNARY_MINUS_SUBEXPR,	"Unary minus not supported in sub-expressions"),
 
 #undef C
 #define C(a, b)		HIST_ERR_##a
···
 #define HIST_FIELD_OPERANDS_MAX	2
 #define HIST_FIELDS_MAX		(TRACING_MAP_FIELDS_MAX + TRACING_MAP_VARS_MAX)
 #define HIST_ACTIONS_MAX	8
+#define HIST_CONST_DIGITS_MAX	21
 
 enum field_op_id {
 	FIELD_OP_NONE,
 	FIELD_OP_PLUS,
 	FIELD_OP_MINUS,
 	FIELD_OP_UNARY_MINUS,
+	FIELD_OP_DIV,
+	FIELD_OP_MULT,
 };
 
 /*
···
 	bool                            read_once;
 
 	unsigned int			var_str_idx;
+
+	/* Numeric literals are represented as u64 */
+	u64				constant;
 };
 
 static u64 hist_field_none(struct hist_field *field,
···
 			   void *event)
 {
 	return 0;
+}
+
+static u64 hist_field_const(struct hist_field *field,
+			   struct tracing_map_elt *elt,
+			   struct trace_buffer *buffer,
+			   struct ring_buffer_event *rbe,
+			   void *event)
+{
+	return field->constant;
 }
 
 static u64 hist_field_counter(struct hist_field *field,
···
 	return val1 - val2;
 }
 
+static u64 hist_field_div(struct hist_field *hist_field,
+			   struct tracing_map_elt *elt,
+			   struct trace_buffer *buffer,
+			   struct ring_buffer_event *rbe,
+			   void *event)
+{
+	struct hist_field *operand1 = hist_field->operands[0];
+	struct hist_field *operand2 = hist_field->operands[1];
+
+	u64 val1 = operand1->fn(operand1, elt, buffer, rbe, event);
+	u64 val2 = operand2->fn(operand2, elt, buffer, rbe, event);
+
+	/* Return -1 for the undefined case */
+	if (!val2)
+		return -1;
+
+	/* Use shift if the divisor is a power of 2 */
+	if (!(val2 & (val2 - 1)))
+		return val1 >> __ffs64(val2);
+
+	return div64_u64(val1, val2);
+}
+
+static u64 hist_field_mult(struct hist_field *hist_field,
+			   struct tracing_map_elt *elt,
+			   struct trace_buffer *buffer,
+			   struct ring_buffer_event *rbe,
+			   void *event)
+{
+	struct hist_field *operand1 = hist_field->operands[0];
+	struct hist_field *operand2 = hist_field->operands[1];
+
+	u64 val1 = operand1->fn(operand1, elt, buffer, rbe, event);
+	u64 val2 = operand2->fn(operand2, elt, buffer, rbe, event);
+
+	return val1 * val2;
+}
+
 static u64 hist_field_unary_minus(struct hist_field *hist_field,
 				  struct tracing_map_elt *elt,
 				  struct trace_buffer *buffer,
···
 	HIST_FIELD_FL_CPU		= 1 << 15,
 	HIST_FIELD_FL_ALIAS		= 1 << 16,
 	HIST_FIELD_FL_BUCKET		= 1 << 17,
+	HIST_FIELD_FL_CONST		= 1 << 18,
 };
 
 struct var_defs {
···
 {
 	if (field->flags & HIST_FIELD_FL_VAR_REF)
 		strcat(expr, "$");
+	else if (field->flags & HIST_FIELD_FL_CONST) {
+		char str[HIST_CONST_DIGITS_MAX];
+
+		snprintf(str, HIST_CONST_DIGITS_MAX, "%llu", field->constant);
+		strcat(expr, str);
+	}
 
 	strcat(expr, hist_field_name(field, 0));
 
···
 	case FIELD_OP_PLUS:
 		strcat(expr, "+");
 		break;
+	case FIELD_OP_DIV:
+		strcat(expr, "/");
+		break;
+	case FIELD_OP_MULT:
+		strcat(expr, "*");
+		break;
 	default:
 		kfree(expr);
 		return NULL;
···
 	return expr;
 }
 
-static int contains_operator(char *str)
+/*
+ * If field_op != FIELD_OP_NONE, *sep points to the root operator
+ * of the expression tree to be evaluated.
+ */
+static int contains_operator(char *str, char **sep)
 {
 	enum field_op_id field_op = FIELD_OP_NONE;
-	char *op;
+	char *minus_op, *plus_op, *div_op, *mult_op;
 
-	op = strpbrk(str, "+-");
-	if (!op)
-		return FIELD_OP_NONE;
 
-	switch (*op) {
-	case '-':
+	/*
+	 * Report the last occurrence of the operators first, so that the
+	 * expression is evaluated left to right. This is important since
+	 * subtraction and division are not associative.
+	 *
+	 *	e.g
+	 *		64/8/4/2 is 1, i.e 64/8/4/2 = ((64/8)/4)/2
+	 *		14-7-5-2 is 0, i.e 14-7-5-2 = ((14-7)-5)-2
+	 */
+
+	/*
+	 * First, find lower precedence addition and subtraction
+	 * since the expression will be evaluated recursively.
+	 */
+	minus_op = strrchr(str, '-');
+	if (minus_op) {
 		/*
-		 * Unfortunately, the modifier ".sym-offset"
-		 * can confuse things.
+		 * Unary minus is not supported in sub-expressions. If
+		 * present, it is always the next root operator.
 		 */
-		if (op - str >= 4 && !strncmp(op - 4, ".sym-offset", 11))
-			return FIELD_OP_NONE;
-
-		if (*str == '-')
+		if (minus_op == str) {
 			field_op = FIELD_OP_UNARY_MINUS;
-		else
-			field_op = FIELD_OP_MINUS;
-		break;
-	case '+':
-		field_op = FIELD_OP_PLUS;
-		break;
-	default:
-		break;
+			goto out;
+		}
+
+		field_op = FIELD_OP_MINUS;
+	}
+
+	plus_op = strrchr(str, '+');
+	if (plus_op || minus_op) {
+		/*
+		 * For operators of the same precedence use to rightmost as the
+		 * root, so that the expression is evaluated left to right.
+		 */
+		if (plus_op > minus_op)
+			field_op = FIELD_OP_PLUS;
+		goto out;
+	}
+
+	/*
+	 * Multiplication and division have higher precedence than addition and
+	 * subtraction.
+	 */
+	div_op = strrchr(str, '/');
+	if (div_op)
+		field_op = FIELD_OP_DIV;
+
+	mult_op = strrchr(str, '*');
+	/*
+	 * For operators of the same precedence use to rightmost as the
+	 * root, so that the expression is evaluated left to right.
+	 */
+	if (mult_op > div_op)
+		field_op = FIELD_OP_MULT;
+
+out:
+	if (sep) {
+		switch (field_op) {
+		case FIELD_OP_UNARY_MINUS:
+		case FIELD_OP_MINUS:
+			*sep = minus_op;
+			break;
+		case FIELD_OP_PLUS:
+			*sep = plus_op;
+			break;
+		case FIELD_OP_DIV:
+			*sep = div_op;
+			break;
+		case FIELD_OP_MULT:
+			*sep = mult_op;
+			break;
+		case FIELD_OP_NONE:
+		default:
+			*sep = NULL;
+			break;
+		}
 	}
 
 	return field_op;
···
 		hist_field->fn = hist_field_counter;
 		hist_field->size = sizeof(u64);
 		hist_field->type = "u64";
+		goto out;
+	}
+
+	if (flags & HIST_FIELD_FL_CONST) {
+		hist_field->fn = hist_field_const;
+		hist_field->size = sizeof(u64);
+		hist_field->type = kstrdup("u64", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
 		goto out;
 	}
 
···
 
 		if (strcmp(var_name, name) == 0) {
 			field = hist_data->attrs->var_defs.expr[i];
-			if (contains_operator(field) || is_var_ref(field))
+			if (contains_operator(field, NULL) || is_var_ref(field))
 				continue;
 			return field;
 		}
···
 			*flags |= HIST_FIELD_FL_HEX;
 		else if (strcmp(modifier, "sym") == 0)
 			*flags |= HIST_FIELD_FL_SYM;
-		else if (strcmp(modifier, "sym-offset") == 0)
+		/*
+		 * 'sym-offset' occurrences in the trigger string are modified
+		 * to 'symXoffset' to simplify arithmetic expression parsing.
+		 */
+		else if (strcmp(modifier, "symXoffset") == 0)
 			*flags |= HIST_FIELD_FL_SYM_OFFSET;
 		else if ((strcmp(modifier, "execname") == 0) &&
 			 (strcmp(field_name, "common_pid") == 0))
···
 	return alias;
 }
 
+static struct hist_field *parse_const(struct hist_trigger_data *hist_data,
+				      char *str, char *var_name,
+				      unsigned long *flags)
+{
+	struct trace_array *tr = hist_data->event_file->tr;
+	struct hist_field *field = NULL;
+	u64 constant;
+
+	if (kstrtoull(str, 0, &constant)) {
+		hist_err(tr, HIST_ERR_EXPECT_NUMBER, errpos(str));
+		return NULL;
+	}
+
+	*flags |= HIST_FIELD_FL_CONST;
+	field = create_hist_field(hist_data, NULL, *flags, var_name);
+	if (!field)
+		return NULL;
+
+	field->constant = constant;
+
+	return field;
+}
+
 static struct hist_field *parse_atom(struct hist_trigger_data *hist_data,
 				     struct trace_event_file *file, char *str,
 				     unsigned long *flags, char *var_name)
···
 	struct hist_field *hist_field = NULL;
 	unsigned long buckets = 0;
 	int ret = 0;
+
+	if (isdigit(str[0])) {
+		hist_field = parse_const(hist_data, str, var_name, flags);
+		if (!hist_field) {
+			ret = -EINVAL;
+			goto out;
+		}
+		return hist_field;
+	}
 
 	s = strchr(str, '.');
 	if (s) {
···
 static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
 				     struct trace_event_file *file,
 				     char *str, unsigned long flags,
-				     char *var_name, unsigned int level);
+				     char *var_name, unsigned int *n_subexprs);
 
 static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
 				      struct trace_event_file *file,
 				      char *str, unsigned long flags,
-				      char *var_name, unsigned int level)
+				      char *var_name, unsigned int *n_subexprs)
 {
 	struct hist_field *operand1, *expr = NULL;
 	unsigned long operand_flags;
 	int ret = 0;
 	char *s;
 
+	/* Unary minus operator, increment n_subexprs */
+	++*n_subexprs;
+
 	/* we support only -(xxx) i.e. explicit parens required */
 
-	if (level > 3) {
+	if (*n_subexprs > 3) {
 		hist_err(file->tr, HIST_ERR_TOO_MANY_SUBEXPR, errpos(str));
 		ret = -EINVAL;
 		goto free;
···
 	}
 
 	s = strrchr(str, ')');
-	if (s)
+	if (s) {
+		 /* unary minus not supported in sub-expressions */
+		if (*(s+1) != '\0') {
+			hist_err(file->tr, HIST_ERR_UNARY_MINUS_SUBEXPR,
+				 errpos(str));
+			ret = -EINVAL;
+			goto free;
+		}
 		*s = '\0';
+	}
 	else {
 		ret = -EINVAL; /* no closing ')' */
 		goto free;
···
 	}
 
 	operand_flags = 0;
-	operand1 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);
+	operand1 = parse_expr(hist_data, file, str, operand_flags, NULL, n_subexprs);
 	if (IS_ERR(operand1)) {
 		ret = PTR_ERR(operand1);
 		goto free;
···
 	return ERR_PTR(ret);
 }
 
+/*
+ * If the operands are var refs, return pointers the
+ * variable(s) referenced in var1 and var2, else NULL.
+ */
 static int check_expr_operands(struct trace_array *tr,
 			       struct hist_field *operand1,
-			       struct hist_field *operand2)
+			       struct hist_field *operand2,
+			       struct hist_field **var1,
+			       struct hist_field **var2)
 {
 	unsigned long operand1_flags = operand1->flags;
 	unsigned long operand2_flags = operand2->flags;
···
 		if (!var)
 			return -EINVAL;
 		operand1_flags = var->flags;
+		*var1 = var;
 	}
 
 	if ((operand2_flags & HIST_FIELD_FL_VAR_REF) ||
···
 		if (!var)
 			return -EINVAL;
 		operand2_flags = var->flags;
+		*var2 = var;
 	}
 
 	if ((operand1_flags & HIST_FIELD_FL_TIMESTAMP_USECS) !=
···
 static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
 				     struct trace_event_file *file,
 				     char *str, unsigned long flags,
-				     char *var_name, unsigned int level)
+				     char *var_name, unsigned int *n_subexprs)
 {
 	struct hist_field *operand1 = NULL, *operand2 = NULL, *expr = NULL;
-	unsigned long operand_flags;
+	struct hist_field *var1 = NULL, *var2 = NULL;
+	unsigned long operand_flags, operand2_flags;
 	int field_op, ret = -EINVAL;
 	char *sep, *operand1_str;
+	hist_field_fn_t op_fn;
+	bool combine_consts;
 
-	if (level > 3) {
+	if (*n_subexprs > 3) {
 		hist_err(file->tr, HIST_ERR_TOO_MANY_SUBEXPR, errpos(str));
 		return ERR_PTR(-EINVAL);
 	}
 
-	field_op = contains_operator(str);
+	field_op = contains_operator(str, &sep);
 
 	if (field_op == FIELD_OP_NONE)
 		return parse_atom(hist_data, file, str, &flags, var_name);
 
 	if (field_op == FIELD_OP_UNARY_MINUS)
-		return parse_unary(hist_data, file, str, flags, var_name, ++level);
+		return parse_unary(hist_data, file, str, flags, var_name, n_subexprs);
 
-	switch (field_op) {
-	case FIELD_OP_MINUS:
-		sep = "-";
-		break;
-	case FIELD_OP_PLUS:
-		sep = "+";
-		break;
-	default:
+	/* Binary operator found, increment n_subexprs */
+	++*n_subexprs;
+
+	/* Split the expression string at the root operator */
+	if (!sep)
 		goto free;
-	}
+	*sep = '\0';
+	operand1_str = str;
+	str = sep+1;
 
-	operand1_str = strsep(&str, sep);
 	if (!operand1_str || !str)
 		goto free;
 
 	operand_flags = 0;
-	operand1 = parse_atom(hist_data, file, operand1_str,
-			      &operand_flags, NULL);
+
+	/* LHS of string is an expression e.g. a+b in a+b+c */
+	operand1 = parse_expr(hist_data, file, operand1_str, operand_flags, NULL, n_subexprs);
 	if (IS_ERR(operand1)) {
 		ret = PTR_ERR(operand1);
 		operand1 = NULL;
···
 		goto free;
 	}
 
-	/* rest of string could be another expression e.g. b+c in a+b+c */
+	/* RHS of string is another expression e.g. c in a+b+c */
 	operand_flags = 0;
-	operand2 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);
+	operand2 = parse_expr(hist_data, file, str, operand_flags, NULL, n_subexprs);
 	if (IS_ERR(operand2)) {
 		ret = PTR_ERR(operand2);
 		operand2 = NULL;
···
 		goto free;
 	}
 
-	ret = check_expr_operands(file->tr, operand1, operand2);
+	switch (field_op) {
+	case FIELD_OP_MINUS:
+		op_fn = hist_field_minus;
+		break;
+	case FIELD_OP_PLUS:
+		op_fn = hist_field_plus;
+		break;
+	case FIELD_OP_DIV:
+		op_fn = hist_field_div;
+		break;
+	case FIELD_OP_MULT:
+		op_fn = hist_field_mult;
+		break;
+	default:
+		ret = -EINVAL;
+		goto free;
+	}
+
+	ret = check_expr_operands(file->tr, operand1, operand2, &var1, &var2);
 	if (ret)
 		goto free;
 
-	flags |= HIST_FIELD_FL_EXPR;
+	operand_flags = var1 ? var1->flags : operand1->flags;
+	operand2_flags = var2 ? var2->flags : operand2->flags;
+
+	/*
+	 * If both operands are constant, the expression can be
+	 * collapsed to a single constant.
+	 */
+	combine_consts = operand_flags & operand2_flags & HIST_FIELD_FL_CONST;
+
+	flags |= combine_consts ? HIST_FIELD_FL_CONST : HIST_FIELD_FL_EXPR;
 
 	flags |= operand1->flags &
 		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
···
 	expr->operands[0] = operand1;
 	expr->operands[1] = operand2;
 
-	/* The operand sizes should be the same, so just pick one */
-	expr->size = operand1->size;
+	if (combine_consts) {
+		if (var1)
+			expr->operands[0] = var1;
+		if (var2)
+			expr->operands[1] = var2;
 
-	expr->operator = field_op;
-	expr->name = expr_str(expr, 0);
-	expr->type = kstrdup_const(operand1->type, GFP_KERNEL);
-	if (!expr->type) {
-		ret = -ENOMEM;
-		goto free;
-	}
+		expr->constant = op_fn(expr, NULL, NULL, NULL, NULL);
 
-	switch (field_op) {
-	case FIELD_OP_MINUS:
-		expr->fn = hist_field_minus;
-		break;
-	case FIELD_OP_PLUS:
-		expr->fn = hist_field_plus;
-		break;
-	default:
-		ret = -EINVAL;
-		goto free;
+		expr->operands[0] = NULL;
+		expr->operands[1] = NULL;
+
+		/*
+		 * var refs won't be destroyed immediately
+		 * See: destroy_hist_field()
+		 */
+		destroy_hist_field(operand2, 0);
+		destroy_hist_field(operand1, 0);
+
+		expr->name = expr_str(expr, 0);
+	} else {
+		expr->fn = op_fn;
+
+		/* The operand sizes should be the same, so just pick one */
+		expr->size = operand1->size;
+
+		expr->operator = field_op;
+		expr->type = kstrdup_const(operand1->type, GFP_KERNEL);
+		if (!expr->type) {
+			ret = -ENOMEM;
+			goto free;
+		}
+
+		expr->name = expr_str(expr, 0);
 	}
 
 	return expr;
- free:
+free:
 	destroy_hist_field(operand1, 0);
 	destroy_hist_field(operand2, 0);
 	destroy_hist_field(expr, 0);
···
 			      unsigned long flags)
 {
 	struct hist_field *hist_field;
-	int ret = 0;
+	int ret = 0, n_subexprs = 0;
 
-	hist_field = parse_expr(hist_data, file, field_str, flags, var_name, 0);
+	hist_field = parse_expr(hist_data, file, field_str, flags, var_name, &n_subexprs);
 	if (IS_ERR(hist_field)) {
 		ret = PTR_ERR(hist_field);
 		goto out;
···
 	struct hist_field *hist_field = NULL;
 	unsigned long flags = 0;
 	unsigned int key_size;
-	int ret = 0;
+	int ret = 0, n_subexprs = 0;
 
 	if (WARN_ON(key_idx >= HIST_FIELDS_MAX))
 		return -EINVAL;
···
 		hist_field = create_hist_field(hist_data, NULL, flags, NULL);
 	} else {
 		hist_field = parse_expr(hist_data, file, field_str, flags,
-					NULL, 0);
+					NULL, &n_subexprs);
 		if (IS_ERR(hist_field)) {
 			ret = PTR_ERR(hist_field);
 			goto out;
···
 					  unsigned long *stacktrace_entries,
 					  unsigned int max_entries)
 {
-	char str[KSYM_SYMBOL_LEN];
 	unsigned int spaces = 8;
 	unsigned int i;
 
···
 			return;
 
 		seq_printf(m, "%*c", 1 + spaces, ' ');
-		sprint_symbol(str, stacktrace_entries[i]);
-		seq_printf(m, "%s\n", str);
+		seq_printf(m, "%pS\n", (void*)stacktrace_entries[i]);
 	}
 }
 
···
 				   struct tracing_map_elt *elt)
 {
 	struct hist_field *key_field;
-	char str[KSYM_SYMBOL_LEN];
 	bool multiline = false;
 	const char *field_name;
 	unsigned int i;
···
 			seq_printf(m, "%s: %llx", field_name, uval);
 		} else if (key_field->flags & HIST_FIELD_FL_SYM) {
 			uval = *(u64 *)(key + key_field->offset);
-			sprint_symbol_no_offset(str, uval);
-			seq_printf(m, "%s: [%llx] %-45s", field_name,
-				   uval, str);
+			seq_printf(m, "%s: [%llx] %-45ps", field_name,
+				   uval, (void *)(uintptr_t)uval);
 		} else if (key_field->flags & HIST_FIELD_FL_SYM_OFFSET) {
 			uval = *(u64 *)(key + key_field->offset);
-			sprint_symbol(str, uval);
-			seq_printf(m, "%s: [%llx] %-55s", field_name,
-				   uval, str);
+			seq_printf(m, "%s: [%llx] %-55pS", field_name,
+				   uval, (void *)(uintptr_t)uval);
 		} else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
 			struct hist_elt_data *elt_data = elt->private_data;
 			char *comm;
···
 
 	if (flags & HIST_FIELD_FL_ALIAS)
 		seq_puts(m, "        HIST_FIELD_FL_ALIAS\n");
+	else if (flags & HIST_FIELD_FL_CONST)
+		seq_puts(m, "        HIST_FIELD_FL_CONST\n");
 }
 
 static int hist_field_debug_show(struct seq_file *m,
···
 		seq_printf(m, "      var.idx (into tracing_map_elt.vars[]): %u\n",
 			   field->var.idx);
 	}
+
+	if (field->flags & HIST_FIELD_FL_CONST)
+		seq_printf(m, "      constant: %llu\n", field->constant);
 
 	if (field->flags & HIST_FIELD_FL_ALIAS)
 		seq_printf(m, "      var_ref_idx (into hist_data->var_refs[]): %u\n",
···
 
 	if (hist_field->flags & HIST_FIELD_FL_CPU)
 		seq_puts(m, "common_cpu");
+	else if (hist_field->flags & HIST_FIELD_FL_CONST)
+		seq_printf(m, "%llu", hist_field->constant);
 	else if (field_name) {
 		if (hist_field->flags & HIST_FIELD_FL_VAR_REF ||
 		    hist_field->flags & HIST_FIELD_FL_ALIAS)
···
 	struct synth_event *se;
 	const char *se_name;
 	bool remove = false;
-	char *trigger, *p;
+	char *trigger, *p, *start;
 	int ret = 0;
 
 	lockdep_assert_held(&event_mutex);
···
 		*(p - 1) = '\0';
 		param = strstrip(p);
 		trigger = strstrip(trigger);
+	}
+
+	/*
+	 * To simplify arithmetic expression parsing, replace occurrences of
+	 * '.sym-offset' modifier with '.symXoffset'
+	 */
+	start = strstr(trigger, ".sym-offset");
+	while (start) {
+		*(start + 4) = 'X';
+		start = strstr(start + 11, ".sym-offset");
 	}
 
 	attrs = parse_hist_trigger_attrs(file->tr, trigger);

kernel/trace/trace_events_synth.c

···
 	if (err)
 		goto err;
 
-	entry = tracefs_create_file("synthetic_events", 0644, NULL,
-				    NULL, &synth_events_fops);
+	entry = tracefs_create_file("synthetic_events", TRACE_MODE_WRITE,
+				    NULL, NULL, &synth_events_fops);
 	if (!entry) {
 		err = -ENODEV;
 		goto err;

kernel/trace/trace_functions.c

···
 		return;
 
 	trace_ctx = tracing_gen_ctx();
-	preempt_disable_notrace();
 
 	cpu = smp_processor_id();
 	data = per_cpu_ptr(tr->array_buffer.data, cpu);
···
 		trace_function(tr, ip, parent_ip, trace_ctx);
 
 	ftrace_test_recursion_unlock(bit);
-	preempt_enable_notrace();
 }
 
 #ifdef CONFIG_UNWINDER_ORC
···
 	if (bit < 0)
 		return;
 
-	preempt_disable_notrace();
-
 	cpu = smp_processor_id();
 	data = per_cpu_ptr(tr->array_buffer.data, cpu);
 	if (atomic_read(&data->disabled))
···
 
 out:
 	ftrace_test_recursion_unlock(bit);
-	preempt_enable_notrace();
 }
 
 static void

kernel/trace/trace_functions_graph.c

···
 	if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
 		return 0;
 
-	return in_irq();
+	return in_hardirq();
 }
 
 int trace_graph_entry(struct ftrace_graph_ent *trace)
···
 	if (ret)
 		return 0;
 
-	trace_create_file("max_graph_depth", 0644, NULL,
+	trace_create_file("max_graph_depth", TRACE_MODE_WRITE, NULL,
 			  NULL, &graph_depth_fops);
 
 	return 0;

kernel/trace/trace_hwlat.c

···
 	int			nmi_cpu;
 };
 
-struct hwlat_kthread_data hwlat_single_cpu_data;
-DEFINE_PER_CPU(struct hwlat_kthread_data, hwlat_per_cpu_data);
+static struct hwlat_kthread_data hwlat_single_cpu_data;
+static DEFINE_PER_CPU(struct hwlat_kthread_data, hwlat_per_cpu_data);
 
 /* Tells NMIs to call back to the hwlat tracer to record timestamps */
 bool trace_hwlat_callback_enabled;
···
 	if (!top_dir)
 		return -ENOMEM;
 
-	hwlat_sample_window = tracefs_create_file("window", 0640,
+	hwlat_sample_window = tracefs_create_file("window", TRACE_MODE_WRITE,
 						  top_dir,
 						  &hwlat_window,
 						  &trace_min_max_fops);
 	if (!hwlat_sample_window)
 		goto err;
 
-	hwlat_sample_width = tracefs_create_file("width", 0644,
+	hwlat_sample_width = tracefs_create_file("width", TRACE_MODE_WRITE,
 						 top_dir,
 						 &hwlat_width,
 						 &trace_min_max_fops);
 	if (!hwlat_sample_width)
 		goto err;
 
-	hwlat_thread_mode = trace_create_file("mode", 0644,
+	hwlat_thread_mode = trace_create_file("mode", TRACE_MODE_WRITE,
 					      top_dir,
 					      NULL,
 					      &thread_mode_fops);

kernel/trace/trace_kprobe.c

···
 
 static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
 {
-	return !!(kprobe_gone(&tk->rp.kp));
+	return kprobe_gone(&tk->rp.kp);
 }
 
 static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
···
 	if (ret)
 		return 0;
 
-	entry = tracefs_create_file("kprobe_events", 0644, NULL,
-				    NULL, &kprobe_events_ops);
+	entry = tracefs_create_file("kprobe_events", TRACE_MODE_WRITE,
+				    NULL, NULL, &kprobe_events_ops);
 
 	/* Event list interface */
 	if (!entry)
 		pr_warn("Could not create tracefs 'kprobe_events' entry\n");
 
 	/* Profile interface */
-	entry = tracefs_create_file("kprobe_profile", 0444, NULL,
-				    NULL, &kprobe_profile_ops);
+	entry = tracefs_create_file("kprobe_profile", TRACE_MODE_READ,
+				    NULL, NULL, &kprobe_profile_ops);
 
 	if (!entry)
 		pr_warn("Could not create tracefs 'kprobe_profile' entry\n");

kernel/trace/trace_osnoise.c

···
 	seq_puts(s, "#                                _-----=> irqs-off\n");
 	seq_puts(s, "#                               / _----=> need-resched\n");
 	seq_puts(s, "#                              | / _---=> hardirq/softirq\n");
-	seq_puts(s, "#                              || / _--=> preempt-depth     ");
-	seq_puts(s, "                       MAX\n");
-
-	seq_puts(s, "#                              || /                         ");
+	seq_puts(s, "#                              || / _--=> preempt-depth\n");
+	seq_puts(s, "#                              ||| / _-=> migrate-disable     ");
+	seq_puts(s, "                    MAX\n");
+	seq_puts(s, "#                              |||| /     delay               ");
 	seq_puts(s, "                    SINGLE      Interference counters:\n");
 
-	seq_puts(s, "#                              ||||               RUNTIME   ");
+	seq_puts(s, "#                              |||||               RUNTIME   ");
 	seq_puts(s, "   NOISE  %% OF CPU  NOISE    +-----------------------------+\n");
 
-	seq_puts(s, "#           TASK-PID      CPU# ||||   TIMESTAMP    IN US    ");
+	seq_puts(s, "#           TASK-PID      CPU# |||||   TIMESTAMP    IN US    ");
 	seq_puts(s, "   IN US  AVAILABLE  IN US     HW    NMI    IRQ   SIRQ THREAD\n");
 
-	seq_puts(s, "#              | |         |   ||||      |           |      ");
+	seq_puts(s, "#              | |         |   |||||      |           |      ");
 	seq_puts(s, "       |    |            |      |      |      |      |      |\n");
 }
 #endif /* CONFIG_PREEMPT_RT */
···
 	seq_puts(s, "#                               / _----=> need-resched\n");
 	seq_puts(s, "#                              | / _---=> hardirq/softirq\n");
 	seq_puts(s, "#                              || / _--=> preempt-depth\n");
-	seq_puts(s, "#                              || /\n");
-	seq_puts(s, "#                              ||||             ACTIVATION\n");
-	seq_puts(s, "#           TASK-PID      CPU# ||||   TIMESTAMP    ID     ");
-	seq_puts(s, "       CONTEXT                LATENCY\n");
-	seq_puts(s, "#              | |         |   ||||      |         |      ");
+	seq_puts(s, "#                              ||| / _-=> migrate-disable\n");
+	seq_puts(s, "#                              |||| /     delay\n");
+	seq_puts(s, "#                              |||||            ACTIVATION\n");
+	seq_puts(s, "#           TASK-PID      CPU# |||||   TIMESTAMP   ID      ");
+	seq_puts(s, "      CONTEXT                 LATENCY\n");
+	seq_puts(s, "#              | |         |   |||||      |         |      ");
 	seq_puts(s, "            |                       |\n");
 }
 #endif /* CONFIG_PREEMPT_RT */
···
 	if (!top_dir)
 		return 0;
 
-	tmp = tracefs_create_file("period_us", 0640, top_dir,
+	tmp = tracefs_create_file("period_us", TRACE_MODE_WRITE, top_dir,
 				  &osnoise_period, &trace_min_max_fops);
 	if (!tmp)
 		goto err;
 
-	tmp = tracefs_create_file("runtime_us", 0644, top_dir,
+	tmp = tracefs_create_file("runtime_us", TRACE_MODE_WRITE, top_dir,
 				  &osnoise_runtime, &trace_min_max_fops);
 	if (!tmp)
 		goto err;
 
-	tmp = tracefs_create_file("stop_tracing_us", 0640, top_dir,
+	tmp = tracefs_create_file("stop_tracing_us", TRACE_MODE_WRITE, top_dir,
 				  &osnoise_stop_tracing_in, &trace_min_max_fops);
 	if (!tmp)
 		goto err;
 
-	tmp = tracefs_create_file("stop_tracing_total_us", 0640, top_dir,
+	tmp = tracefs_create_file("stop_tracing_total_us", TRACE_MODE_WRITE, top_dir,
 				  &osnoise_stop_tracing_total, &trace_min_max_fops);
 	if (!tmp)
 		goto err;
 
-	tmp = trace_create_file("cpus", 0644, top_dir, NULL, &cpus_fops);
+	tmp = trace_create_file("cpus", TRACE_MODE_WRITE, top_dir, NULL, &cpus_fops);
 	if (!tmp)
 		goto err;
 #ifdef CONFIG_TIMERLAT_TRACER
 #ifdef CONFIG_STACKTRACE
-	tmp = tracefs_create_file("print_stack", 0640, top_dir,
+	tmp = tracefs_create_file("print_stack", TRACE_MODE_WRITE, top_dir,
 				  &osnoise_print_stack, &trace_min_max_fops);
 	if (!tmp)
 		goto err;
 #endif
 
-	tmp = tracefs_create_file("timerlat_period_us", 0640, top_dir,
+	tmp = tracefs_create_file("timerlat_period_us", TRACE_MODE_WRITE, top_dir,
 				  &timerlat_period, &trace_min_max_fops);
 	if (!tmp)
 		goto err;

kernel/trace/trace_output.c

···
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/ftrace.h>
+#include <linux/kprobes.h>
 #include <linux/sched/clock.h>
 #include <linux/sched/mm.h>
 
···
 }
 EXPORT_SYMBOL_GPL(trace_output_call);
 
-#ifdef CONFIG_KRETPROBES
-static inline const char *kretprobed(const char *name)
+static inline const char *kretprobed(const char *name, unsigned long addr)
 {
-	static const char tramp_name[] = "kretprobe_trampoline";
-	int size = sizeof(tramp_name);
-
-	if (strncmp(tramp_name, name, size) == 0)
+	if (is_kretprobe_trampoline(addr))
 		return "[unknown/kretprobe'd]";
 	return name;
 }
-#else
-static inline const char *kretprobed(const char *name)
-{
-	return name;
-}
-#endif /* CONFIG_KRETPROBES */
 
 void
 trace_seq_print_sym(struct trace_seq *s, unsigned long address, bool offset)
···
 		sprint_symbol(str, address);
 	else
 		kallsyms_lookup(address, NULL, NULL, NULL, str);
-	name = kretprobed(str);
+	name = kretprobed(str, address);
 
 	if (name && strlen(name)) {
 		trace_seq_puts(s, name);

kernel/trace/trace_printk.c

···
 	if (ret)
 		return 0;
 
-	trace_create_file("printk_formats", 0444, NULL,
+	trace_create_file("printk_formats", TRACE_MODE_READ, NULL,
 				    NULL, &ftrace_formats_fops);
 
 	return 0;

kernel/trace/trace_recursion_record.c

···
 {
 	struct dentry *dentry;
 
-	dentry = trace_create_file("recursed_functions", 0644, NULL, NULL,
-				   &recursed_functions_fops);
+	dentry = trace_create_file("recursed_functions", TRACE_MODE_WRITE,
+				   NULL, NULL, &recursed_functions_fops);
 	if (!dentry)
 		pr_warn("WARNING: Failed to create recursed_functions\n");
 	return 0;

kernel/trace/trace_selftest.c

···
 	if (trace_selftest_test_probe3_cnt != 4)
 		goto out_free;
 
+	/* Remove trace function from probe 3 */
+	func1_name = "!" __stringify(DYN_FTRACE_TEST_NAME);
+	len1 = strlen(func1_name);
+
+	ftrace_set_filter(&test_probe3, func1_name, len1, 0);
+
+	DYN_FTRACE_TEST_NAME();
+
+	print_counts();
+
+	if (trace_selftest_test_probe1_cnt != 3)
+		goto out_free;
+	if (trace_selftest_test_probe2_cnt != 2)
+		goto out_free;
+	if (trace_selftest_test_probe3_cnt != 4)
+		goto out_free;
+	if (cnt > 1) {
+		if (trace_selftest_test_global_cnt == 0)
+			goto out_free;
+	}
+	if (trace_selftest_test_dyn_cnt == 0)
+		goto out_free;
+
+	DYN_FTRACE_TEST_NAME2();
+
+	print_counts();
+
+	if (trace_selftest_test_probe1_cnt != 3)
+		goto out_free;
+	if (trace_selftest_test_probe2_cnt != 3)
+		goto out_free;
+	if (trace_selftest_test_probe3_cnt != 5)
+		goto out_free;
+
 	ret = 0;
  out_free:
 	unregister_ftrace_function(dyn_ops);
···
 	.retfunc		= &trace_graph_return,
 };
 
+#if defined(CONFIG_DYNAMIC_FTRACE) && \
+    defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS)
+#define TEST_DIRECT_TRAMP
+noinline __noclone static void trace_direct_tramp(void) { }
+#endif
+
 /*
  * Pretty much the same than for the function tracer from which the selftest
  * has been borrowed.
···
 {
 	int ret;
 	unsigned long count;
+	char *func_name __maybe_unused;
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 	if (ftrace_filter_param) {
···
 		goto out;
 	}
 
-	/* Don't test dynamic tracing, the function tracer already did */
+#ifdef TEST_DIRECT_TRAMP
+	tracing_reset_online_cpus(&tr->array_buffer);
+	set_graph_array(tr);
 
+	/*
+	 * Some archs *cough*PowerPC*cough* add characters to the
+	 * start of the function names. We simply put a '*' to
+	 * accommodate them.
+	 */
+	func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
+	ftrace_set_global_filter(func_name, strlen(func_name), 1);
+
+	/*
+	 * Register direct function together with graph tracer
+	 * and make sure we get graph trace.
+	 */
+	ret = register_ftrace_direct((unsigned long) DYN_FTRACE_TEST_NAME,
+				     (unsigned long) trace_direct_tramp);
+	if (ret)
+		goto out;
+
+	ret = register_ftrace_graph(&fgraph_ops);
+	if (ret) {
+		warn_failed_init_tracer(trace, ret);
+		goto out;
+	}
+
+	DYN_FTRACE_TEST_NAME();
+
+	count = 0;
+
+	tracing_stop();
+	/* check the trace buffer */
+	ret = trace_test_buffer(&tr->array_buffer, &count);
+
+	unregister_ftrace_graph(&fgraph_ops);
+
+	ret = unregister_ftrace_direct((unsigned long) DYN_FTRACE_TEST_NAME,
+				       (unsigned long) trace_direct_tramp);
+	if (ret)
+		goto out;
+
+	tracing_start();
+
+	if (!ret && !count) {
+		ret = -1;
+		goto out;
+	}
+#endif
+
+	/* Don't test dynamic tracing, the function tracer already did */
 out:
 	/* Stop it if we failed */
 	if (ret)

kernel/trace/trace_stack.c

···
 	if (ret)
 		return 0;
 
-	trace_create_file("stack_max_size", 0644, NULL,
+	trace_create_file("stack_max_size", TRACE_MODE_WRITE, NULL,
 			&stack_trace_max_size, &stack_max_size_fops);
 
-	trace_create_file("stack_trace", 0444, NULL,
+	trace_create_file("stack_trace", TRACE_MODE_READ, NULL,
 			NULL, &stack_trace_fops);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-	trace_create_file("stack_trace_filter", 0644, NULL,
+	trace_create_file("stack_trace_filter", TRACE_MODE_WRITE, NULL,
 			  &trace_ops, &stack_trace_filter_fops);
 #endif
 

kernel/trace/trace_stat.c

···
 	if (!stat_dir && (ret = tracing_stat_init()))
 		return ret;
 
-	session->file = tracefs_create_file(session->ts->name, 0644,
-					    stat_dir,
-					    session, &tracing_stat_fops);
+	session->file = tracefs_create_file(session->ts->name, TRACE_MODE_WRITE,
+					    stat_dir, session,
+					    &tracing_stat_fops);
 	if (!session->file)
 		return -ENOMEM;
 	return 0;

kernel/trace/trace_uprobe.c

···
 	if (ret)
 		return 0;
 
-	trace_create_file("uprobe_events", 0644, NULL,
+	trace_create_file("uprobe_events", TRACE_MODE_WRITE, NULL,
 				    NULL, &uprobe_events_ops);
 	/* Profile interface */
-	trace_create_file("uprobe_profile", 0444, NULL,
+	trace_create_file("uprobe_profile", TRACE_MODE_READ, NULL,
 				    NULL, &uprobe_profile_ops);
 	return 0;
 }

kernel/trace/tracing_map.c

···
 	return err;
 }
 
-static int cmp_entries_dup(const struct tracing_map_sort_entry **a,
-			   const struct tracing_map_sort_entry **b)
+static int cmp_entries_dup(const void *A, const void *B)
 {
+	const struct tracing_map_sort_entry *a, *b;
 	int ret = 0;
 
-	if (memcmp((*a)->key, (*b)->key, (*a)->elt->map->key_size))
+	a = *(const struct tracing_map_sort_entry **)A;
+	b = *(const struct tracing_map_sort_entry **)B;
+
+	if (memcmp(a->key, b->key, a->elt->map->key_size))
 		ret = 1;
 
 	return ret;
 }
 
-static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
-			   const struct tracing_map_sort_entry **b)
+static int cmp_entries_sum(const void *A, const void *B)
 {
 	const struct tracing_map_elt *elt_a, *elt_b;
+	const struct tracing_map_sort_entry *a, *b;
 	struct tracing_map_sort_key *sort_key;
 	struct tracing_map_field *field;
 	tracing_map_cmp_fn_t cmp_fn;
 	void *val_a, *val_b;
 	int ret = 0;
 
-	elt_a = (*a)->elt;
-	elt_b = (*b)->elt;
+	a = *(const struct tracing_map_sort_entry **)A;
+	b = *(const struct tracing_map_sort_entry **)B;
+
+	elt_a = a->elt;
+	elt_b = b->elt;
 
 	sort_key = &elt_a->map->sort_key;
 
···
 	return ret;
 }
 
-static int cmp_entries_key(const struct tracing_map_sort_entry **a,
-			   const struct tracing_map_sort_entry **b)
+static int cmp_entries_key(const void *A, const void *B)
 {
 	const struct tracing_map_elt *elt_a, *elt_b;
+	const struct tracing_map_sort_entry *a, *b;
 	struct tracing_map_sort_key *sort_key;
 	struct tracing_map_field *field;
 	tracing_map_cmp_fn_t cmp_fn;
 	void *val_a, *val_b;
 	int ret = 0;
 
-	elt_a = (*a)->elt;
-	elt_b = (*b)->elt;
+	a = *(const struct tracing_map_sort_entry **)A;
+	b = *(const struct tracing_map_sort_entry **)B;
+
+	elt_a = a->elt;
+	elt_b = b->elt;
 
 	sort_key = &elt_a->map->sort_key;
 
···
 			   struct tracing_map_sort_key *primary_key,
 			   struct tracing_map_sort_key *secondary_key)
 {
-	int (*primary_fn)(const struct tracing_map_sort_entry **,
-			  const struct tracing_map_sort_entry **);
-	int (*secondary_fn)(const struct tracing_map_sort_entry **,
-			    const struct tracing_map_sort_entry **);
+	int (*primary_fn)(const void *, const void *);
+	int (*secondary_fn)(const void *, const void *);
 	unsigned i, start = 0, n_sub = 1;
 
 	if (is_key(map, primary_key->field_idx))
···
 			     unsigned int n_sort_keys,
 			     struct tracing_map_sort_entry ***sort_entries)
 {
-	int (*cmp_entries_fn)(const struct tracing_map_sort_entry **,
-			      const struct tracing_map_sort_entry **);
+	int (*cmp_entries_fn)(const void *, const void *);
 	struct tracing_map_sort_entry *sort_entry, **entries;
 	int i, n_entries, ret;
 

lib/Kconfig.debug

···
 	  If unsure, say N.
 
 config KPROBES_SANITY_TEST
-	bool "Kprobes sanity tests"
+	tristate "Kprobes sanity tests"
 	depends on DEBUG_KERNEL
 	depends on KPROBES
+	depends on KUNIT
 	help
 	  This option provides for testing basic kprobes functionality on
 	  boot. Samples of kprobe and kretprobe are inserted and

lib/Makefile

···
 obj-$(CONFIG_TEST_LOCKUP) += test_lockup.o
 obj-$(CONFIG_TEST_HMM) += test_hmm.o
 obj-$(CONFIG_TEST_FREE_PAGES) += test_free_pages.o
+obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
 
 #
 # CFLAGS for compiling floating point code inside the kernel. x86/Makefile turns

lib/bootconfig.c

···
  * Masami Hiramatsu <[e-mail]>
  */
 
-#define pr_fmt(fmt)    "bootconfig: " fmt
-
+#ifdef __KERNEL__
 #include <linux/bootconfig.h>
 #include <linux/bug.h>
 #include <linux/ctype.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/memblock.h>
-#include <linux/printk.h>
 #include <linux/string.h>
+#else /* !__KERNEL__ */
+/*
+ * NOTE: This is only for tools/bootconfig, because tools/bootconfig will
+ * run the parser sanity test.
+ * This does NOT mean lib/bootconfig.c is available in the user space.
+ * However, if you change this file, please make sure the tools/bootconfig
+ * has no issue on building and running.
+ */
+#include <linux/bootconfig.h>
+#endif
 
 /*
  * Extra Boot Config (XBC) is given as tree-structured ascii text of
···
 static int xbc_err_pos __initdata;
 static int open_brace[XBC_DEPTH_MAX] __initdata;
 static int brace_index __initdata;
+
+#ifdef __KERNEL__
+static inline void * __init xbc_alloc_mem(size_t size)
+{
+	return memblock_alloc(size, SMP_CACHE_BYTES);
+}
+
+static inline void __init xbc_free_mem(void *addr, size_t size)
+{
+	memblock_free_ptr(addr, size);
+}
+
+#else /* !__KERNEL__ */
+
+static inline void *xbc_alloc_mem(size_t size)
+{
+	return malloc(size);
+}
+
+static inline void xbc_free_mem(void *addr, size_t size)
+{
+	free(addr);
+}
+#endif
+/**
+ * xbc_get_info() - Get the information of loaded boot config
+ * @node_size: A pointer to store the number of nodes.
+ * @data_size: A pointer to store the size of bootconfig data.
+ *
+ * Get the number of used nodes in @node_size if it is not NULL,
+ * and the size of bootconfig data in @data_size if it is not NULL.
+ * Return 0 if the boot config is initialized, or return -ENODEV.
+ */
+int __init xbc_get_info(int *node_size, size_t *data_size)
+{
+	if (!xbc_data)
+		return -ENODEV;
+
+	if (node_size)
+		*node_size = xbc_node_num;
+	if (data_size)
+		*data_size = xbc_data_size;
+	return 0;
+}
 
 static int __init xbc_parse_error(const char *msg, const char *p)
 {
···
 				      struct xbc_node *node,
 				      char *buf, size_t size)
 {
-	u16 keys[XBC_DEPTH_MAX];
+	uint16_t keys[XBC_DEPTH_MAX];
 	int depth = 0, ret = 0, total = 0;
 
 	if (!node || node == root)
···
 
 /* XBC parse and tree build */
 
-static int __init xbc_init_node(struct xbc_node *node, char *data, u32 flag)
+static int __init xbc_init_node(struct xbc_node *node, char *data, uint32_t flag)
 {
 	unsigned long offset = data - xbc_data;
 
 	if (WARN_ON(offset >= XBC_DATA_MAX))
 		return -EINVAL;
 
-	node->data = (u16)offset | flag;
+	node->data = (uint16_t)offset | flag;
 	node->child = 0;
 	node->next = 0;
 
 	return 0;
 }
 
-static struct xbc_node * __init xbc_add_node(char *data, u32 flag)
+static struct xbc_node * __init xbc_add_node(char *data, uint32_t flag)
 {
 	struct xbc_node *node;
 
···
 	return node;
 }
 
-static struct xbc_node * __init __xbc_add_sibling(char *data, u32 flag, bool head)
+static struct xbc_node * __init __xbc_add_sibling(char *data, uint32_t flag, bool head)
 {
 	struct xbc_node *sib, *node = xbc_add_node(data, flag);
 
···
 	return node;
 }
 
-static inline struct xbc_node * __init xbc_add_sibling(char *data, u32 flag)
+static inline struct xbc_node * __init xbc_add_sibling(char *data, uint32_t flag)
 {
 	return __xbc_add_sibling(data, flag, false);
 }
 
-static inline struct xbc_node * __init xbc_add_head_sibling(char *data, u32 flag)
+static inline struct xbc_node * __init xbc_add_head_sibling(char *data, uint32_t flag)
 {
 	return __xbc_add_sibling(data, flag, true);
 }
 
-static inline __init struct xbc_node *xbc_add_child(char *data, u32 flag)
+static inline __init struct xbc_node *xbc_add_child(char *data, uint32_t flag)
 {
 	struct xbc_node *node = xbc_add_sibling(data, flag);
 
···
 	return 0;
 }
 
-/**
- * xbc_destroy_all() - Clean up all parsed bootconfig
- *
- * This clears all data structures of parsed bootconfig on memory.
- * If you need to reuse xbc_init() with new boot config, you can
- * use this.
- */
-void __init xbc_destroy_all(void)
-{
-	xbc_data = NULL;
-	xbc_data_size = 0;
-	xbc_node_num = 0;
-	memblock_free_ptr(xbc_nodes, sizeof(struct xbc_node) * XBC_NODE_MAX);
-	xbc_nodes = NULL;
-	brace_index = 0;
-}
-
-/**
- * xbc_init() - Parse given XBC file and build XBC internal tree
- * @buf: boot config text
- * @emsg: A pointer of const char * to store the error message
- * @epos: A pointer of int to store the error position
- *
- * This parses the boot config text in @buf. @buf must be a
- * null terminated string and smaller than XBC_DATA_MAX.
- * Return the number of stored nodes (>0) if succeeded, or -errno
- * if there is any error.
- * In error cases, @emsg will be updated with an error message and
- * @epos will be updated with the error position which is the byte offset
- * of @buf. If the error is not a parser error, @epos will be -1.
- */
-int __init xbc_init(char *buf, const char **emsg, int *epos)
+/* Need to setup xbc_data and xbc_nodes before call this. */
+static int __init xbc_parse_tree(void)
 {
 	char *p, *q;
-	int ret, c;
+	int ret = 0, c;
 
-	if (epos)
-		*epos = -1;
-
-	if (xbc_data) {
-		if (emsg)
-			*emsg = "Bootconfig is already initialized";
-		return -EBUSY;
-	}
-
-	ret = strlen(buf);
-	if (ret > XBC_DATA_MAX - 1 || ret == 0) {
-		if (emsg)
-			*emsg = ret ? "Config data is too big" :
-				"Config data is empty";
-		return -ERANGE;
-	}
-
-	xbc_nodes = memblock_alloc(sizeof(struct xbc_node) * XBC_NODE_MAX,
-				   SMP_CACHE_BYTES);
-	if (!xbc_nodes) {
-		if (emsg)
-			*emsg = "Failed to allocate bootconfig nodes";
-		return -ENOMEM;
-	}
-	memset(xbc_nodes, 0, sizeof(struct xbc_node) * XBC_NODE_MAX);
-	xbc_data = buf;
-	xbc_data_size = ret + 1;
 	last_parent = NULL;
-
-	p = buf;
+	p = xbc_data;
 	do {
 		q = strpbrk(p, "{}=+;:\n#");
 		if (!q) {
···
 		}
 	} while (!ret);
 
+	return ret;
+}
+
+/**
+ * xbc_exit() - Clean up all parsed bootconfig
+ *
+ * This clears all data structures of parsed bootconfig on memory.
+ * If you need to reuse xbc_init() with new boot config, you can
+ * use this.
+ */
+void __init xbc_exit(void)
+{
+	xbc_free_mem(xbc_data, xbc_data_size);
+	xbc_data = NULL;
+	xbc_data_size = 0;
+	xbc_node_num = 0;
+	xbc_free_mem(xbc_nodes, sizeof(struct xbc_node) * XBC_NODE_MAX);
+	xbc_nodes = NULL;
+	brace_index = 0;
+}
+
+/**
+ * xbc_init() - Parse given XBC file and build XBC internal tree
+ * @data: The boot config text original data
+ * @size: The size of @data
+ * @emsg: A pointer of const char * to store the error message
+ * @epos: A pointer of int to store the error position
+ *
+ * This parses the boot config text in @data. @size must be smaller
+ * than XBC_DATA_MAX.
+ * Return the number of stored nodes (>0) if succeeded, or -errno
+ * if there is any error.
+ * In error cases, @emsg will be updated with an error message and
+ * @epos will be updated with the error position which is the byte offset
+ * of @buf. If the error is not a parser error, @epos will be -1.
+ */
+int __init xbc_init(const char *data, size_t size, const char **emsg, int *epos)
+{
+	int ret;
+
+	if (epos)
+		*epos = -1;
+
+	if (xbc_data) {
+		if (emsg)
+			*emsg = "Bootconfig is already initialized";
+		return -EBUSY;
+	}
+	if (size > XBC_DATA_MAX || size == 0) {
+		if (emsg)
+			*emsg = size ? "Config data is too big" :
+				"Config data is empty";
+		return -ERANGE;
+	}
+
+	xbc_data = xbc_alloc_mem(size + 1);
+	if (!xbc_data) {
+		if (emsg)
+			*emsg = "Failed to allocate bootconfig data";
+		return -ENOMEM;
+	}
+	memcpy(xbc_data, data, size);
+	xbc_data[size] = '\0';
+	xbc_data_size = size + 1;
+
+	xbc_nodes = xbc_alloc_mem(sizeof(struct xbc_node) * XBC_NODE_MAX);
+	if (!xbc_nodes) {
+		if (emsg)
+			*emsg = "Failed to allocate bootconfig nodes";
+		xbc_exit();
+		return -ENOMEM;
+	}
+	memset(xbc_nodes, 0, sizeof(struct xbc_node) * XBC_NODE_MAX);
+
+	ret = xbc_parse_tree();
 	if (!ret)
 		ret = xbc_verify_tree();
 
···
 			*epos = xbc_err_pos;
 		if (emsg)
 			*emsg = xbc_err_msg;
-		xbc_destroy_all();
+		xbc_exit();
 	} else
 		ret = xbc_node_num;
 
 	return ret;
-}
-
-/**
- * xbc_debug_dump() - Dump current XBC node list
- *
- * Dump the current XBC node list on printk buffer for debug.
- */
-void __init xbc_debug_dump(void)
-{
-	int i;
-
-	for (i = 0; i < xbc_node_num; i++) {
-		pr_debug("[%d] %s (%s) .next=%d, .child=%d .parent=%d\n", i,
-			xbc_node_get_data(xbc_nodes + i),
-			xbc_node_is_value(xbc_nodes + i) ? "value" : "key",
-			xbc_nodes[i].next, xbc_nodes[i].child,
-			xbc_nodes[i].parent);
-	}
 }

lib/error-inject.c

···
 #include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/slab.h>
+#include <asm/sections.h>
 
 /* Whitelist of symbols that can be overridden for error injection. */
 static LIST_HEAD(error_injection_list);
···
 
 	mutex_lock(&ei_mutex);
 	for (iter = start; iter < end; iter++) {
-		entry = arch_deref_entry_point((void *)iter->addr);
+		entry = (unsigned long)dereference_symbol_descriptor((void *)iter->addr);
 
 		if (!kernel_text_address(entry) ||
 		    !kallsyms_lookup_size_offset(entry, &size, &offset)) {

lib/test_kprobes.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * test_kprobes.c - simple sanity test for *probes
+ *
+ * Copyright IBM Corp. 2008
+ */
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/random.h>
+#include <kunit/test.h>
+
+#define div_factor 3
+
+static u32 rand1, preh_val, posth_val;
+static u32 (*target)(u32 value);
+static u32 (*target2)(u32 value);
+static struct kunit *current_test;
+
+static unsigned long (*internal_target)(void);
+static unsigned long (*stacktrace_target)(void);
+static unsigned long (*stacktrace_driver)(void);
+static unsigned long target_return_address[2];
+
+static noinline u32 kprobe_target(u32 value)
+{
+	return (value / div_factor);
+}
+
+static int kp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	KUNIT_EXPECT_FALSE(current_test, preemptible());
+	preh_val = (rand1 / div_factor);
+	return 0;
+}
+
+static void kp_post_handler(struct kprobe *p, struct pt_regs *regs,
+		unsigned long flags)
+{
+	KUNIT_EXPECT_FALSE(current_test, preemptible());
+	KUNIT_EXPECT_EQ(current_test, preh_val, (rand1 / div_factor));
+	posth_val = preh_val + div_factor;
+}
+
+static struct kprobe kp = {
+	.symbol_name = "kprobe_target",
+	.pre_handler = kp_pre_handler,
+	.post_handler = kp_post_handler
+};
+
+static void test_kprobe(struct kunit *test)
+{
+	current_test = test;
+	KUNIT_EXPECT_EQ(test, 0, register_kprobe(&kp));
+	target(rand1);
+	unregister_kprobe(&kp);
+	KUNIT_EXPECT_NE(test, 0, preh_val);
+	KUNIT_EXPECT_NE(test, 0, posth_val);
+}
+
+static noinline u32 kprobe_target2(u32 value)
+{
+	return (value / div_factor) + 1;
+}
+
+static noinline unsigned long kprobe_stacktrace_internal_target(void)
+{
+	if (!target_return_address[0])
+		target_return_address[0] = (unsigned long)__builtin_return_address(0);
+	return target_return_address[0];
+}
+
+static noinline unsigned long kprobe_stacktrace_target(void)
+{
+	if (!target_return_address[1])
+		target_return_address[1] = (unsigned long)__builtin_return_address(0);
+
+	if (internal_target)
+		internal_target();
+
+	return target_return_address[1];
+}
+
+static noinline unsigned long kprobe_stacktrace_driver(void)
+{
+	if (stacktrace_target)
+		stacktrace_target();
+
+	/* This is for preventing inlining the function */
+	return (unsigned long)__builtin_return_address(0);
+}
+
+static int kp_pre_handler2(struct kprobe *p, struct pt_regs *regs)
+{
+	preh_val = (rand1 / div_factor) + 1;
+	return 0;
+}
+
+static void kp_post_handler2(struct kprobe *p, struct pt_regs *regs,
+		unsigned long flags)
+{
+	KUNIT_EXPECT_EQ(current_test, preh_val, (rand1 / div_factor) + 1);
+	posth_val = preh_val + div_factor;
+}
+
+static struct kprobe kp2 = {
+	.symbol_name = "kprobe_target2",
+	.pre_handler = kp_pre_handler2,
+	.post_handler = kp_post_handler2
+};
+
+static void test_kprobes(struct kunit *test)
+{
+	struct kprobe *kps[2] = {&kp, &kp2};
+
+	current_test = test;
+
+	/* addr and flags should be cleard for reusing kprobe. */
+	kp.addr = NULL;
+	kp.flags = 0;
+
+	KUNIT_EXPECT_EQ(test, 0, register_kprobes(kps, 2));
+	preh_val = 0;
+	posth_val = 0;
+	target(rand1);
+
+	KUNIT_EXPECT_NE(test, 0, preh_val);
+	KUNIT_EXPECT_NE(test, 0, posth_val);
+
+	preh_val = 0;
+	posth_val = 0;
+	target2(rand1);
+
+	KUNIT_EXPECT_NE(test, 0, preh_val);
+	KUNIT_EXPECT_NE(test, 0, posth_val);
+	unregister_kprobes(kps, 2);
+}
+
+#ifdef CONFIG_KRETPROBES
+static u32 krph_val;
+
+static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	KUNIT_EXPECT_FALSE(current_test, preemptible());
+	krph_val = (rand1 / div_factor);
+	return 0;
+}
+
+static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	unsigned long ret = regs_return_value(regs);
+
+	KUNIT_EXPECT_FALSE(current_test, preemptible());
+	KUNIT_EXPECT_EQ(current_test, ret, rand1 / div_factor);
+	KUNIT_EXPECT_NE(current_test, krph_val, 0);
+	krph_val = rand1;
+	return 0;
+}
+
+static struct kretprobe rp = {
+	.handler	= return_handler,
+	.entry_handler  = entry_handler,
+	.kp.symbol_name = "kprobe_target"
+};
+
+static void test_kretprobe(struct kunit *test)
+{
+	current_test = test;
+	KUNIT_EXPECT_EQ(test, 0, register_kretprobe(&rp));
+	target(rand1);
+	unregister_kretprobe(&rp);
+	KUNIT_EXPECT_EQ(test, krph_val, rand1);
+}
+
+static int return_handler2(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	unsigned long ret = regs_return_value(regs);
+
+	KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor) + 1);
+	KUNIT_EXPECT_NE(current_test, krph_val, 0);
+	krph_val = rand1;
+	return 0;
+}
+
+static struct kretprobe rp2 = {
+	.handler	= return_handler2,
+	.entry_handler  = entry_handler,
+	.kp.symbol_name = "kprobe_target2"
+};
+
+static void test_kretprobes(struct kunit *test)
+{
+	struct kretprobe *rps[2] = {&rp, &rp2};
+
+	current_test = test;
+	/* addr and flags should be cleard for reusing kprobe. */
+	rp.kp.addr = NULL;
+	rp.kp.flags = 0;
+	KUNIT_EXPECT_EQ(test, 0, register_kretprobes(rps, 2));
+
+	krph_val = 0;
+	target(rand1);
+	KUNIT_EXPECT_EQ(test, krph_val, rand1);
+
+	krph_val = 0;
+	target2(rand1);
+	KUNIT_EXPECT_EQ(test, krph_val, rand1);
+	unregister_kretprobes(rps, 2);
+}
+
+#ifdef CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
+#define STACK_BUF_SIZE 16
+static unsigned long stack_buf[STACK_BUF_SIZE];
+
+static int stacktrace_return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	unsigned long retval = regs_return_value(regs);
+	int i, ret;
+
+	KUNIT_EXPECT_FALSE(current_test, preemptible());
+	KUNIT_EXPECT_EQ(current_test, retval, target_return_address[1]);
+
+	/*
+	 * Test stacktrace inside the kretprobe handler, this will involves
+	 * kretprobe trampoline, but must include correct return address
+	 * of the target function.
+	 */
+	ret = stack_trace_save(stack_buf, STACK_BUF_SIZE, 0);
+	KUNIT_EXPECT_NE(current_test, ret, 0);
+
+	for (i = 0; i < ret; i++) {
+		if (stack_buf[i] == target_return_address[1])
+			break;
+	}
+	KUNIT_EXPECT_NE(current_test, i, ret);
+
+#if !IS_MODULE(CONFIG_KPROBES_SANITY_TEST)
+	/*
+	 * Test stacktrace from pt_regs at the return address. Thus the stack
+	 * trace must start from the target return address.
+	 */
+	ret = stack_trace_save_regs(regs, stack_buf, STACK_BUF_SIZE, 0);
+	KUNIT_EXPECT_NE(current_test, ret, 0);
+	KUNIT_EXPECT_EQ(current_test, stack_buf[0], target_return_address[1]);
+#endif
+
+	return 0;
+}
+
+static struct kretprobe rp3 = {
+	.handler	= stacktrace_return_handler,
+	.kp.symbol_name = "kprobe_stacktrace_target"
+};
+
+static void test_stacktrace_on_kretprobe(struct kunit *test)
+{
+	unsigned long myretaddr = (unsigned long)__builtin_return_address(0);
+
+	current_test = test;
+	rp3.kp.addr = NULL;
+	rp3.kp.flags = 0;
+
+	/*
+	 * Run the stacktrace_driver() to record correct return address in
+	 * stacktrace_target() and ensure stacktrace_driver() call is not
+	 * inlined by checking the return address of stacktrace_driver()
+	 * and the return address of this function is different.
+	 */
+	KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
+
+	KUNIT_ASSERT_EQ(test, 0, register_kretprobe(&rp3));
+	KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
+	unregister_kretprobe(&rp3);
+}
+
+static int stacktrace_internal_return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	unsigned long retval = regs_return_value(regs);
+	int i, ret;
+
+	KUNIT_EXPECT_FALSE(current_test, preemptible());
+	KUNIT_EXPECT_EQ(current_test, retval, target_return_address[0]);
+
+	/*
+	 * Test stacktrace inside the kretprobe handler for nested case.
+	 * The unwinder will find the kretprobe_trampoline address on the
+	 * return address, and kretprobe must solve that.
+	 */
+	ret = stack_trace_save(stack_buf, STACK_BUF_SIZE, 0);
+	KUNIT_EXPECT_NE(current_test, ret, 0);
+
+	for (i = 0; i < ret - 1; i++) {
+		if (stack_buf[i] == target_return_address[0]) {
+			KUNIT_EXPECT_EQ(current_test, stack_buf[i + 1], target_return_address[1]);
+			break;
+		}
+	}
+	KUNIT_EXPECT_NE(current_test, i, ret);
+
+#if !IS_MODULE(CONFIG_KPROBES_SANITY_TEST)
+	/* Ditto for the regs version. */
+	ret = stack_trace_save_regs(regs, stack_buf, STACK_BUF_SIZE, 0);
+	KUNIT_EXPECT_NE(current_test, ret, 0);
+	KUNIT_EXPECT_EQ(current_test, stack_buf[0], target_return_address[0]);
+	KUNIT_EXPECT_EQ(current_test, stack_buf[1], target_return_address[1]);
+#endif
+
+	return 0;
+}
+
+static struct kretprobe rp4 = {
+	.handler	= stacktrace_internal_return_handler,
+	.kp.symbol_name = "kprobe_stacktrace_internal_target"
+};
+
+static void test_stacktrace_on_nested_kretprobe(struct kunit *test)
+{
+	unsigned long myretaddr = (unsigned long)__builtin_return_address(0);
+	struct kretprobe *rps[2] = {&rp3, &rp4};
+
+	current_test = test;
+	rp3.kp.addr = NULL;
+	rp3.kp.flags = 0;
+
+	//KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
+
+	KUNIT_ASSERT_EQ(test, 0, register_kretprobes(rps, 2));
+	KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
+	unregister_kretprobes(rps, 2);
+}
+#endif /* CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE */
+
+#endif /* CONFIG_KRETPROBES */
+
+static int kprobes_test_init(struct kunit *test)
+{
+	target = kprobe_target;
+	target2 = kprobe_target2;
+	stacktrace_target = kprobe_stacktrace_target;
+	internal_target = kprobe_stacktrace_internal_target;
+	stacktrace_driver = kprobe_stacktrace_driver;
+
+	do {
+		rand1 = prandom_u32();
+	} while (rand1 <= div_factor);
+	return 0;
+}
+
+static struct kunit_case kprobes_testcases[] = {
+	KUNIT_CASE(test_kprobe),
+	KUNIT_CASE(test_kprobes),
+#ifdef CONFIG_KRETPROBES
+	KUNIT_CASE(test_kretprobe),
+	KUNIT_CASE(test_kretprobes),
+#ifdef CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
+	KUNIT_CASE(test_stacktrace_on_kretprobe),
+	KUNIT_CASE(test_stacktrace_on_nested_kretprobe),
+#endif
+#endif
+	{}
+};
+
+static struct kunit_suite kprobes_test_suite = {
+	.name = "kprobes_test",
+	.init = kprobes_test_init,
+	.test_cases = kprobes_testcases,
+};
+
+kunit_test_suites(&kprobes_test_suite);
+
+MODULE_LICENSE("GPL");

samples/ftrace/Makefile

···
 obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct.o
 obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-too.o
 obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-modify.o
+obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-multi.o
 
 CFLAGS_sample-trace-array.o := -I$(src)
 obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += sample-trace-array.o

samples/ftrace/ftrace-direct-multi.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+
+#include <linux/mm.h> /* for handle_mm_fault() */
+#include <linux/ftrace.h>
+#include <linux/sched/stat.h>
+
+void my_direct_func(unsigned long ip)
+{
+	trace_printk("ip %lx\n", ip);
+}
+
+extern void my_tramp(void *);
+
+asm (
+"	.pushsection    .text, \"ax\", @progbits\n"
+"	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
+"   my_tramp:"
+"	pushq %rbp\n"
+"	movq %rsp, %rbp\n"
+"	pushq %rdi\n"
+"	movq 8(%rbp), %rdi\n"
+"	call my_direct_func\n"
+"	popq %rdi\n"
+"	leave\n"
+"	ret\n"
+"	.size		my_tramp, .-my_tramp\n"
+"	.popsection\n"
+);
+
+static struct ftrace_ops direct;
+
+static int __init ftrace_direct_multi_init(void)
+{
+	ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
+	ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
+
+	return register_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
+}
+
+static void __exit ftrace_direct_multi_exit(void)
+{
+	unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
+}
+
+module_init(ftrace_direct_multi_init);
+module_exit(ftrace_direct_multi_exit);
+
+MODULE_AUTHOR("Jiri Olsa");
+MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
+MODULE_LICENSE("GPL");

samples/kprobes/kretprobe_example.c

···
 	ret = register_kretprobe(&my_kretprobe);
 	if (ret < 0) {
 		pr_err("register_kretprobe failed, returned %d\n", ret);
-		return -1;
+		return ret;
 	}
 	pr_info("Planted return probe at %s: %p\n",
 			my_kretprobe.kp.symbol_name, my_kretprobe.kp.addr);

tools/bootconfig/Makefile

···
 ALL_TARGETS := bootconfig
 ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))
 
-all: $(ALL_PROGRAMS)
+all: $(ALL_PROGRAMS) test
 
-$(OUTPUT)bootconfig: main.c $(LIBSRC)
+$(OUTPUT)bootconfig: main.c include/linux/bootconfig.h $(LIBSRC)
 	$(CC) $(filter %.c,$^) $(CFLAGS) -o $@
 
 test: $(ALL_PROGRAMS) test-bootconfig.sh

tools/bootconfig/include/linux/bootconfig.h

···
 #ifndef _BOOTCONFIG_LINUX_BOOTCONFIG_H
 #define _BOOTCONFIG_LINUX_BOOTCONFIG_H
 
-#include "../../../../include/linux/bootconfig.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <ctype.h>
+#include <errno.h>
+#include <string.h>
+
 
 #ifndef fallthrough
 # define fallthrough
 #endif
+
+#define WARN_ON(cond)	\
+	((cond) ? printf("Internal warning(%s:%d, %s): %s\n",	\
+			__FILE__, __LINE__, __func__, #cond) : 0)
+
+#define unlikely(cond)	(cond)
+
+/* Copied from lib/string.c */
+static inline char *skip_spaces(const char *str)
+{
+	while (isspace(*str))
+		++str;
+	return (char *)str;
+}
+
+static inline char *strim(char *s)
+{
+	size_t size;
+	char *end;
+
+	size = strlen(s);
+	if (!size)
+		return s;
+
+	end = s + size - 1;
+	while (end >= s && isspace(*end))
+		end--;
+	*(end + 1) = '\0';
+
+	return skip_spaces(s);
+}
+
+#define __init
+#define __initdata
+
+#include "../../../../include/linux/bootconfig.h"
 
 #endif

tools/bootconfig/include/linux/bug.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _SKC_LINUX_BUG_H
-#define _SKC_LINUX_BUG_H
-
-#include <stdio.h>
-#include <stdlib.h>
-
-#define WARN_ON(cond)	\
-	((cond) ? printf("Internal warning(%s:%d, %s): %s\n",	\
-			__FILE__, __LINE__, __func__, #cond) : 0)
-
-#endif

tools/bootconfig/include/linux/ctype.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _SKC_LINUX_CTYPE_H
-#define _SKC_LINUX_CTYPE_H
-
-#include <ctype.h>
-
-#endif

tools/bootconfig/include/linux/errno.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _SKC_LINUX_ERRNO_H
-#define _SKC_LINUX_ERRNO_H
-
-#include <asm/errno.h>
-
-#endif

tools/bootconfig/include/linux/kernel.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _SKC_LINUX_KERNEL_H
-#define _SKC_LINUX_KERNEL_H
-
-#include <stdlib.h>
-#include <stdbool.h>
-
-#include <linux/printk.h>
-
-typedef unsigned short u16;
-typedef unsigned int   u32;
-
-#define unlikely(cond)	(cond)
-
-#define __init
-#define __initdata
-
-#endif

tools/bootconfig/include/linux/memblock.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _XBC_LINUX_MEMBLOCK_H
-#define _XBC_LINUX_MEMBLOCK_H
-
-#include <stdlib.h>
-
-#define SMP_CACHE_BYTES	0
-#define memblock_alloc(size, align)	malloc(size)
-#define memblock_free_ptr(paddr, size)	free(paddr)
-
-#endif

tools/bootconfig/include/linux/printk.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _SKC_LINUX_PRINTK_H
-#define _SKC_LINUX_PRINTK_H
-
-#include <stdio.h>
-
-#define printk(fmt, ...) printf(fmt, ##__VA_ARGS__)
-
-#define pr_err printk
-#define pr_warn	printk
-#define pr_info	printk
-#define pr_debug printk
-
-#endif

tools/bootconfig/include/linux/string.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _SKC_LINUX_STRING_H
-#define _SKC_LINUX_STRING_H
-
-#include <string.h>
-
-/* Copied from lib/string.c */
-static inline char *skip_spaces(const char *str)
-{
-	while (isspace(*str))
-		++str;
-	return (char *)str;
-}
-
-static inline char *strim(char *s)
-{
-	size_t size;
-	char *end;
-
-	size = strlen(s);
-	if (!size)
-		return s;
-
-	end = s + size - 1;
-	while (end >= s && isspace(*end))
-		end--;
-	*(end + 1) = '\0';
-
-	return skip_spaces(s);
-}
-
-#endif

tools/bootconfig/main.c

···
 #include <errno.h>
 #include <endian.h>
 
-#include <linux/kernel.h>
 #include <linux/bootconfig.h>
+
+#define pr_err(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
 
 static int xbc_show_value(struct xbc_node *node, bool semicolon)
 {
···
 {
 	struct stat stat;
 	int ret;
-	u32 size = 0, csum = 0, rcsum;
+	uint32_t size = 0, csum = 0, rcsum;
 	char magic[BOOTCONFIG_MAGIC_LEN];
 	const char *msg;
 
···
 	if (lseek(fd, -(8 + BOOTCONFIG_MAGIC_LEN), SEEK_END) < 0)
 		return pr_errno("Failed to lseek for size", -errno);
 
-	if (read(fd, &size, sizeof(u32)) < 0)
+	if (read(fd, &size, sizeof(uint32_t)) < 0)
 		return pr_errno("Failed to read size", -errno);
 	size = le32toh(size);
 
-	if (read(fd, &csum, sizeof(u32)) < 0)
+	if (read(fd, &csum, sizeof(uint32_t)) < 0)
 		return pr_errno("Failed to read checksum", -errno);
 	csum = le32toh(csum);
 
···
 		return -EINVAL;
 	}
 
-	ret = xbc_init(*buf, &msg, NULL);
+	ret = xbc_init(*buf, size, &msg, NULL);
 	/* Wrong data */
 	if (ret < 0) {
 		pr_err("parse error: %s.\n", msg);
···
 	if (!copy)
 		return -ENOMEM;
 
-	ret = xbc_init(buf, &msg, &pos);
+	ret = xbc_init(buf, len, &msg, &pos);
 	if (ret < 0)
 		show_xbc_error(copy, msg, pos);
 	free(copy);
···
 	size_t total_size;
 	struct stat stat;
 	const char *msg;
-	u32 size, csum;
+	uint32_t size, csum;
 	int pos, pad;
 	int ret, fd;
 
···
 
 	/* Backup the bootconfig data */
 	data = calloc(size + BOOTCONFIG_ALIGN +
-		      sizeof(u32) + sizeof(u32) + BOOTCONFIG_MAGIC_LEN, 1);
+		      sizeof(uint32_t) + sizeof(uint32_t) + BOOTCONFIG_MAGIC_LEN, 1);
 	if (!data)
 		return -ENOMEM;
 	memcpy(data, buf, size);
 
 	/* Check the data format */
-	ret = xbc_init(buf, &msg, &pos);
+	ret = xbc_init(buf, size, &msg, &pos);
 	if (ret < 0) {
 		show_xbc_error(data, msg, pos);
 		free(data);
···
 		return ret;
 	}
 	printf("Apply %s to %s\n", xbc_path, path);
+	xbc_get_info(&ret, NULL);
 	printf("\tNumber of nodes: %d\n", ret);
 	printf("\tSize: %u bytes\n", (unsigned int)size);
 	printf("\tChecksum: %d\n", (unsigned int)csum);
 
 	/* TODO: Check the options by schema */
-	xbc_destroy_all();
+	xbc_exit();
 	free(buf);
 
 	/* Remove old boot config if exists */
···
 	}
 
 	/* To align up the total size to BOOTCONFIG_ALIGN, get padding size */
-	total_size = stat.st_size + size + sizeof(u32) * 2 + BOOTCONFIG_MAGIC_LEN;
+	total_size = stat.st_size + size + sizeof(uint32_t) * 2 + BOOTCONFIG_MAGIC_LEN;
 	pad = ((total_size + BOOTCONFIG_ALIGN - 1) & (~BOOTCONFIG_ALIGN_MASK)) - total_size;
 	size += pad;
 
 	/* Add a footer */
 	p = data + size;
-	*(u32 *)p = htole32(size);
-	p += sizeof(u32);
+	*(uint32_t *)p = htole32(size);
+	p += sizeof(uint32_t);
 
-	*(u32 *)p = htole32(csum);
-	p += sizeof(u32);
+	*(uint32_t *)p = htole32(csum);
+	p += sizeof(uint32_t);
 
 	memcpy(p, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);
 	p += BOOTCONFIG_MAGIC_LEN;

tools/include/linux/objtool.h

···
 	static void __used __section(".discard.func_stack_frame_non_standard") \
 		*__func_stack_frame_non_standard_##func = func
 
+/*
+ * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
+ * for the case where a function is intentionally missing frame pointer setup,
+ * but otherwise needs objtool/ORC coverage when frame pointers are disabled.
+ */
+#ifdef CONFIG_FRAME_POINTER
+#define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
+#else
+#define STACK_FRAME_NON_STANDARD_FP(func)
+#endif
+
 #else /* __ASSEMBLY__ */
 
 /*
···
 #define UNWIND_HINT(sp_reg, sp_offset, type, end)	\
 	"\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
+#define STACK_FRAME_NON_STANDARD_FP(func)
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0

tools/objtool/check.c

···
 	}
 
 	while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
-		if (insn->hint && !insn->visited) {
+		if (insn->hint && !insn->visited && !insn->ignore) {
 			ret = validate_branch(file, insn->func, insn, state);
 			if (ret && backtrace)
 				BT_FUNC("<=== (hint)", insn);

tools/testing/selftests/ftrace/ftracetest

···
     exit 1
   fi
 done
-(cd $TRACING_DIR; initialize_ftrace) # for cleanup
+(cd $TRACING_DIR; finish_ftrace) # for cleanup
 
 prlog ""
 prlog "# of passed: " `echo $PASSED_CASES | wc -w`

tools/testing/selftests/ftrace/test.d/functions

···
     [ -f uprobe_events ] && echo > uprobe_events
     [ -f synthetic_events ] && echo > synthetic_events
     [ -f snapshot ] && echo 0 > snapshot
+
+# Stop tracing while reading the trace file by default, to prevent
+# the test results while checking it and to avoid taking a long time
+# to check the result.
+    [ -f options/pause-on-trace ] && echo 1 > options/pause-on-trace
+
     clear_trace
     enable_tracing
+}
+
+finish_ftrace() {
+    initialize_ftrace
+# And recover it to default.
+    [ -f options/pause-on-trace ] && echo 0 > options/pause-on-trace
 }
 
 check_requires() { # Check required files and tracers

tools/tracing/latency/latency-collector.c

···
 				mutex_lock(&print_mtx);
 				check_signals();
 				write_or_die(fd_stdout, queue_full_warning,
-					     sizeof(queue_full_warning));
+					     strlen(queue_full_warning));
 				mutex_unlock(&print_mtx);
 			}
 			modified--;