function_graph: Everyone uses HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, remove it

All architectures that implement function graph also implements
HAVE_FUNCTION_GRAPH_RET_ADDR_PTR. Remove it, as it is no longer a
differentiator.

Link: https://lore.kernel.org/linux-trace-kernel/[e-mail]

Cc: Masami Hiramatsu <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Mathieu Desnoyers <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Guo Ren <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: WANG Xuerui <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Cc: Christophe Leroy <[e-mail]>
Cc: "Naveen N. Rao" <[e-mail]>
Cc: Paul Walmsley <[e-mail]>
Cc: Palmer Dabbelt <[e-mail]>
Cc: Albert Ou <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Alexander Gordeev <[e-mail]>
Cc: Christian Borntraeger <[e-mail]>
Cc: Sven Schnelle <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Signed-off-by: Steven Rostedt (Google) <[e-mail]>

Documentation/trace/ftrace-design.rst

···
 
 Similarly, when you call ftrace_return_to_handler(), pass it the frame pointer.
 
-HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
---------------------------------
-
-An arch may pass in a pointer to the return address on the stack.  This
-prevents potential stack unwinding issues where the unwinder gets out of
-sync with ret_stack and the wrong addresses are reported by
-ftrace_graph_ret_addr().
-
-Adding support for it is easy: just define the macro in asm/ftrace.h and
-pass the return address pointer as the 'retp' argument to
-ftrace_push_return_trace().
-
 HAVE_SYSCALL_TRACEPOINTS
 ------------------------
 

arch/arm64/include/asm/ftrace.h

···
 
 #define HAVE_FUNCTION_GRAPH_FP_TEST
 
-/*
- * HAVE_FUNCTION_GRAPH_RET_ADDR_PTR means that the architecture can provide a
- * "return address pointer" which can be used to uniquely identify a return
- * address which has been overwritten.
- *
- * On arm64 we use the address of the caller's frame record, which remains the
- * same for the lifetime of the instrumented function, unlike the return
- * address in the LR.
- */
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
 #define ARCH_SUPPORTS_FTRACE_OPS 1
 #else

arch/csky/include/asm/ftrace.h

···
 
 #define HAVE_FUNCTION_GRAPH_FP_TEST
 
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-
 #define ARCH_SUPPORTS_FTRACE_OPS 1
 
 #define MCOUNT_ADDR	((unsigned long)_mcount)

arch/loongarch/include/asm/ftrace.h

···
 struct dyn_arch_ftrace { };
 
 #define ARCH_SUPPORTS_FTRACE_OPS 1
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 
 #define ftrace_init_nop ftrace_init_nop
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);

arch/powerpc/include/asm/ftrace.h

···
 #define MCOUNT_ADDR		((unsigned long)(_mcount))
 #define MCOUNT_INSN_SIZE	4 /* sizeof mcount call */
 
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-
 /* Ignore unused weak functions which will have larger offsets */
 #if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)
 #define FTRACE_MCOUNT_MAX_OFFSET	16

arch/riscv/include/asm/ftrace.h

···
 #if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_FRAME_POINTER)
 #define HAVE_FUNCTION_GRAPH_FP_TEST
 #endif
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 
 #define ARCH_SUPPORTS_FTRACE_OPS 1
 #ifndef __ASSEMBLY__

arch/s390/include/asm/ftrace.h

···
 #ifndef _ASM_S390_FTRACE_H
 #define _ASM_S390_FTRACE_H
 
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 #define ARCH_SUPPORTS_FTRACE_OPS 1
 #define MCOUNT_INSN_SIZE	6
 

arch/x86/include/asm/ftrace.h

···
 #define ARCH_SUPPORTS_FTRACE_OPS 1
 #endif
 
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-
 #ifndef __ASSEMBLY__
 extern void __fentry__(void);
 

include/linux/ftrace.h

···
 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
 	unsigned long fp;
 #endif
-#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 	unsigned long *retp;
-#endif
 };
 
 /*

kernel/trace/fgraph.c

···
 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
 	ret_stack->fp = frame_pointer;
 #endif
-#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 	ret_stack->retp = retp;
-#endif
 	return offset;
 }
 
···
  * will be assigned that location so that if called again, it will continue
  * where it left off.
  *
- * @retp is a pointer to the return address on the stack.  It's ignored if
- * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
+ * @retp is a pointer to the return address on the stack.
  */
-#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
 				    unsigned long ret, unsigned long *retp)
 {
···
 
 	return ret;
 }
-#else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
-unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
-				    unsigned long ret, unsigned long *retp)
-{
-	struct ftrace_ret_stack *ret_stack;
-	unsigned long return_handler = (unsigned long)dereference_kernel_function_descriptor(return_to_handler);
-	int offset = task->curr_ret_stack;
-	int i;
-
-	if (ret != return_handler)
-		return ret;
-
-	if (!idx)
-		return ret;
-
-	i = *idx;
-	do {
-		ret_stack = get_ret_stack(task, offset, &offset);
-		if (ret_stack && ret_stack->ret == return_handler)
-			continue;
-		i--;
-	} while (i >= 0 && ret_stack);
-
-	if (ret_stack)
-		return ret_stack->ret;
-
-	return ret;
-}
-#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
 
 static struct ftrace_ops graph_ops = {
 	.func			= ftrace_graph_func,