tracehook: TIF_NOTIFY_RESUME
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>
This commit is contained in:
parent
b787f7ba67
commit
64b1208d5b
|
@ -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> */
|
#endif /* <linux/tracehook.h> */
|
||||||
|
|
Loading…
Reference in New Issue