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

Peter Zijlstra
2020-02-21T16:15:12Z

On Fri, Feb 21, 2020 at 02:34:19PM +0100, Peter Zijlstra wrote:
> 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);
> +

For giggles, I just found:

do_signal()
get_signal()
task_work_run()