um/ptrace: Implement HAVE_SYSCALL_TRACEPOINTS

Implement syscall tracepoints through the generic tracing infrastructure.

Signed-off-by: Thomas Weißschuh <[e-mail]>
Reviewed-by: Nam Cao <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Johannes Berg <[e-mail]>

arch/um/Kconfig

···
 	select HAVE_RUST
 	select ARCH_HAS_UBSAN
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_SYSCALL_TRACEPOINTS
 	select THREAD_INFO_IN_TASK
 
 config MMU

arch/um/include/asm/thread_info.h

···
 #define TIF_NOTIFY_RESUME	8
 #define TIF_SECCOMP		9	/* secure computing */
 #define TIF_SINGLESTEP		10	/* single stepping userspace */
+#define TIF_SYSCALL_TRACEPOINT	11	/* syscall tracepoint instrumentation */
+
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)

arch/um/kernel/ptrace.c

···
 #include <linux/uaccess.h>
 #include <asm/ptrace-abi.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/syscalls.h>
+
 void user_enable_single_step(struct task_struct *child)
 {
 	set_tsk_thread_flag(child, TIF_SINGLESTEP);
···
 			    UPT_SYSCALL_ARG3(&regs->regs),
 			    UPT_SYSCALL_ARG4(&regs->regs));
 
+	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
+		trace_sys_enter(regs, UPT_SYSCALL_NR(&regs->regs));
+
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		return 0;
 
···
 	/* Fake a debug trap */
 	if (test_thread_flag(TIF_SINGLESTEP))
 		send_sigtrap(&regs->regs, 0);
+
+	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
+		trace_sys_exit(regs, PT_REGS_SYSCALL_RET(regs));
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		return;