tracehook: TIF_NOTIFY_RESUME (64b1208d) · Commits · 戴 / test

This adds tracehook.h inlines to enable a new arch feature in support of user debugging/tracing. This is not used yet, but it lays the groundwork for a debugger to be able to wrangle a task that's possibly running, without interrupting its syscalls in progress. Each arch should define TIF_NOTIFY_RESUME, and in their entry.S code treat it much like TIF_SIGPENDING. That is, it causes you to take the slow path when returning to user mode, where you get the full user-mode state accessible as for signal handling or ptrace. The arch code should check TIF_NOTIFY_RESUME after handling TIF_SIGPENDING. When it's set, clear it and then call tracehook_notify_resume(). In future, tracing code will call set_notify_resume() when it wants to get a callback in tracehook_notify_resume(). Signed-off-by:

Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Reviewed-by:

Ingo Molnar <mingo@elte.hu> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/tracehook.h

+34 −0

Original line number	Diff line number	Diff line
		@@ -537,4 +537,38 @@ static inline void tracehook_report_death(struct task_struct *task,
		{
		}

		#ifdef TIF_NOTIFY_RESUME
		/**
		* set_notify_resume - cause tracehook_notify_resume() to be called
		* @task: task that will call tracehook_notify_resume()
		*
		* Calling this arranges that @task will call tracehook_notify_resume()
		* before returning to user mode. If it's already running in user mode,
		* it will enter the kernel and call tracehook_notify_resume() soon.
		* If it's blocked, it will not be woken.
		*/
		static inline void set_notify_resume(struct task_struct *task)
		{
		if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME))
		kick_process(task);
		}

		/**
		* tracehook_notify_resume - report when about to return to user mode
		* @regs: user-mode registers of @current task
		*
		* This is called when %TIF_NOTIFY_RESUME has been set. Now we are
		* about to return to user mode, and the user state in @regs can be
		* inspected or adjusted. The caller in arch code has cleared
		* %TIF_NOTIFY_RESUME before the call. If the flag gets set again
		* asynchronously, this will be called again before we return to
		* user mode.
		*
		* Called without locks.
		*/
		static inline void tracehook_notify_resume(struct pt_regs *regs)
		{
		}
		#endif /* TIF_NOTIFY_RESUME */

		#endif /* <linux/tracehook.h> */

Admin message