[PATCH v4 03/27] x86/entry: Flip _TIF_SIGPENDING and _TIF_NOTIFY_RESUME handling

Peter Zijlstra
2020-02-21T13:50:33Z

Make sure we run task_work before we hit any kind of userspace -- very
much including signals.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/entry/common.c | 8
usr/src/linux-2.6/arch/x86/entry/common.c | 440 ------------------------------
2 files changed, 4 insertions(+), 444 deletions(-)

--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -155,16 +155,16 @@ 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();