Re: [patch V4 part 1 05/36] x86/entry: Flip _TIF_SIGPENDING and _TIF_NOTIFY_RESUME handling

From: Alexandre Chartre
Date: Wed May 06 2020 - 09:08:43 EST



On 5/5/20 3:16 PM, Thomas Gleixner wrote:
Make sure task_work runs before any kind of userspace -- very much
including signals -- is invoked.

Suggested-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/entry/common.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>

alex.

--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -156,16 +156,16 @@ static void exit_to_usermode_loop(struct
if (cached_flags & _TIF_PATCH_PENDING)
klp_update_patch_state(current);
- /* deal with pending signal delivery */
- if (cached_flags & _TIF_SIGPENDING)
- do_signal(regs);
-
if (cached_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
rseq_handle_notify_resume(NULL, regs);
}
+ /* deal with pending signal delivery */
+ if (cached_flags & _TIF_SIGPENDING)
+ do_signal(regs);
+
if (cached_flags & _TIF_USER_RETURN_NOTIFY)
fire_user_return_notifiers();