[v5] user-only: Cleanup SIGSEGV and SIGBUS handling

[PATCH v5 04/67] accel/tcg: Fold cpu_exit_tb_from_sighandler into caller

Richard Henderson posted 67 patches 4 years, 3 months ago

Diff against v6 v7
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Maintainers: Paolo Bonzini <pbonzini@redhat.com>, Taylor Simpson <tsimpson@quicinc.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, David Hildenbrand <david@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Greg Kurz <groug@kaod.org>, Cornelia Huck <cohuck@redhat.com>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, Richard Henderson <richard.henderson@linaro.org>, "Philippe Mathieu-Daudé" <f4bug@amsat.org>, Thomas Huth <thuth@redhat.com>, David Gibson <david@gibson.dropbear.id.au>, Artyom Tarasenko <atar4qemu@gmail.com>, Laurent Vivier <laurent@vivier.eu>, Aurelien Jarno <aurelien@aurel32.net>, Eduardo Habkost <ehabkost@redhat.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Riku Voipio <riku.voipio@iki.fi>, Peter Maydell <peter.maydell@linaro.org>, Yoshinori Sato <ysato@users.sourceforge.jp>, Jiaxun Yang <jiaxun.yang@flygoat.com>, "Philippe Mathieu-Daudé" <philmd@redhat.com>

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[PATCH v5 04/67] accel/tcg: Fold cpu_exit_tb_from_sighandler into caller

Posted by Richard Henderson 4 years, 3 months ago

Remove the comment about siglongjmp.  We do use sigsetjmp
in the main cpu loop, but we do not save the signal mask
as most exits from the cpu loop do not require them.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/user-exec.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index cb63e528c5..744af19397 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -46,17 +46,6 @@ __thread uintptr_t helper_retaddr;
 
 //#define DEBUG_SIGNAL
 
-/* exit the current TB from a signal handler. The host registers are
-   restored in a state compatible with the CPU emulator
- */
-static void QEMU_NORETURN cpu_exit_tb_from_sighandler(CPUState *cpu,
-                                                      sigset_t *old_set)
-{
-    /* XXX: use siglongjmp ? */
-    sigprocmask(SIG_SETMASK, old_set, NULL);
-    cpu_loop_exit_noexc(cpu);
-}
-
 /*
  * Adjust the pc to pass to cpu_restore_state; return the memop type.
  */
@@ -155,7 +144,8 @@ bool handle_sigsegv_accerr_write(CPUState *cpu, sigset_t *old_set,
          * currently executing TB was modified and must be exited
          * immediately.  Clear helper_retaddr for next execution.
          */
-        cpu_exit_tb_from_sighandler(cpu, old_set);
+        sigprocmask(SIG_SETMASK, old_set, NULL);
+        cpu_loop_exit_noexc(cpu);
         /* NORETURN */
     default:
         g_assert_not_reached();
-- 
2.25.1

Re: [PATCH v5 04/67] accel/tcg: Fold cpu_exit_tb_from_sighandler into caller

Posted by Warner Losh 4 years, 3 months ago

On Thu, Oct 14, 2021 at 10:10 PM Richard Henderson <
richard.henderson@linaro.org> wrote:

> Remove the comment about siglongjmp.  We do use sigsetjmp
> in the main cpu loop, but we do not save the signal mask
> as most exits from the cpu loop do not require them.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  accel/tcg/user-exec.c | 14 ++------------
>  1 file changed, 2 insertions(+), 12 deletions(-)
>

Reviewed-by: Warner Losh <imp@bsdimp.com>



> diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
> index cb63e528c5..744af19397 100644
> --- a/accel/tcg/user-exec.c
> +++ b/accel/tcg/user-exec.c
> @@ -46,17 +46,6 @@ __thread uintptr_t helper_retaddr;
>
>  //#define DEBUG_SIGNAL
>
> -/* exit the current TB from a signal handler. The host registers are
> -   restored in a state compatible with the CPU emulator
> - */
> -static void QEMU_NORETURN cpu_exit_tb_from_sighandler(CPUState *cpu,
> -                                                      sigset_t *old_set)
> -{
> -    /* XXX: use siglongjmp ? */
> -    sigprocmask(SIG_SETMASK, old_set, NULL);
> -    cpu_loop_exit_noexc(cpu);
> -}
> -
>  /*
>   * Adjust the pc to pass to cpu_restore_state; return the memop type.
>   */
> @@ -155,7 +144,8 @@ bool handle_sigsegv_accerr_write(CPUState *cpu,
> sigset_t *old_set,
>           * currently executing TB was modified and must be exited
>           * immediately.  Clear helper_retaddr for next execution.
>           */
> -        cpu_exit_tb_from_sighandler(cpu, old_set);
> +        sigprocmask(SIG_SETMASK, old_set, NULL);
> +        cpu_loop_exit_noexc(cpu);
>          /* NORETURN */
>      default:
>          g_assert_not_reached();
> --
> 2.25.1
>
>