From: "Alex Bennée" <alex.bennee@linaro.org>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: qemu-devel@nongnu.org, laurent@vivier.eu
Subject: Re: [PATCH 00/21] linux-user: Move signal trampolines to new page
Date: Wed, 16 Jun 2021 16:05:48 +0100 [thread overview]
Message-ID: <87pmwlg88j.fsf@linaro.org> (raw)
In-Reply-To: <20210616011209.1446045-1-richard.henderson@linaro.org> (Richard Henderson's message of "Tue, 15 Jun 2021 18:11:48 -0700")
Richard Henderson <richard.henderson@linaro.org> writes:
> It is my guess that the majority of the flakiness with the
> linux-user signals.c test is due to a race condition between
> translation and page writes. I vaguely recall a bug report
> about this, but I cannot find it now.
>
> Since the vast majority of "self-modifying code" is due to
> signal delivery, work around this by allocating a new page,
> into which we write the signal handlers.
>
> A better workaround would be to implement the vdso that is
> required by many guests. However, that is a much larger
> problem, and some guests do not define a vdso in upstream
> linux. This serves as a decent fallback.
>
> Neither bit of work, I will note, solves the posited race
> condition described above.
Well this certainly solves the failures I was seeing with
s390x-on-s390x:
retry.py -n 500 -c -- ./qemu-s390x ./tests/tcg/s390x-linux-user/signals
Results summary:
0: 500 times (100.00%), avg time 2.253 (0.00 varience/0.00 deviation)
Ran command 500 times, 500 passes
However qemu-hppa (on x86_64 host) still has the stuborn 1% failure rate
(-static build):
Results summary:
0: 198 times (99.00%), avg time 2.255 (0.00 varience/0.00 deviation)
-4: 2 times (1.00%), avg time 0.252 (0.00 varience/0.00 deviation)
Ran command 200 times, 198 passes
So have a:
Tested-by: Alex Bennée <alex.bennee@linaro.org>
(for s390x at least)
--
Alex Bennée
next prev parent reply other threads:[~2021-06-16 15:07 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 1:11 [PATCH 00/21] linux-user: Move signal trampolines to new page Richard Henderson
2021-06-16 1:11 ` [PATCH 01/21] linux-user: Add infrastructure for a signal trampoline page Richard Henderson
2021-06-16 13:36 ` Max Filippov
2021-06-16 1:11 ` [PATCH 02/21] linux-user/aarch64: Implement setup_sigtramp Richard Henderson
2021-06-16 17:00 ` Philippe Mathieu-Daudé
2021-06-16 1:11 ` [PATCH 03/21] linux-user/arm: Force v2 frames for fdpic Richard Henderson
2021-06-16 17:01 ` Philippe Mathieu-Daudé
2021-06-16 1:11 ` [PATCH 04/21] linux-user/arm: Implement setup_sigtramp Richard Henderson
2021-06-16 13:46 ` Alex Bennée
2021-06-16 13:49 ` Alex Bennée
2021-06-16 17:40 ` Richard Henderson
2021-06-16 1:11 ` [PATCH 05/21] linux-user/alpha: " Richard Henderson
2021-06-16 16:56 ` Philippe Mathieu-Daudé
2021-06-16 1:11 ` [PATCH 06/21] linux-user/cris: " Richard Henderson
2021-06-16 16:37 ` Philippe Mathieu-Daudé
2021-06-16 1:11 ` [PATCH 07/21] linux-user/hexagon: " Richard Henderson
2021-06-16 8:07 ` Taylor Simpson
2021-06-16 15:05 ` Richard Henderson
2021-06-16 15:50 ` Richard Henderson
2021-06-16 21:37 ` Taylor Simpson
2021-06-16 23:15 ` Richard Henderson
2021-06-16 1:11 ` [PATCH 08/21] linux-user/hppa: Document non-use of setup_sigtramp Richard Henderson
2021-06-16 10:46 ` Philippe Mathieu-Daudé
2021-06-16 21:16 ` Alex Bennée
2021-06-16 1:11 ` [PATCH 09/21] linux-user/i386: Implement setup_sigtramp Richard Henderson
2021-06-16 1:11 ` [PATCH 10/21] linux-user/m68k: " Richard Henderson
2021-06-16 16:42 ` Philippe Mathieu-Daudé
2021-06-16 1:11 ` [PATCH 11/21] linux-user/microblaze: " Richard Henderson
2021-06-16 16:43 ` Philippe Mathieu-Daudé
2021-06-16 1:12 ` [PATCH 12/21] linux-user/mips: " Richard Henderson
2021-06-16 16:48 ` Philippe Mathieu-Daudé
2021-06-16 1:12 ` [PATCH 13/21] linux-user/nios2: Document non-use of setup_sigtramp Richard Henderson
2021-06-16 1:12 ` [PATCH 14/21] linux-user/openrisc: Implement setup_sigtramp Richard Henderson
2021-06-16 16:49 ` Philippe Mathieu-Daudé
2021-06-17 0:24 ` Stafford Horne
2021-06-16 1:12 ` [PATCH 15/21] linux-user/ppc: " Richard Henderson
2021-06-16 1:12 ` [PATCH 16/21] linux-user/riscv: " Richard Henderson
2021-06-16 16:50 ` Philippe Mathieu-Daudé
2021-06-18 1:29 ` Alistair Francis
2021-06-16 1:12 ` [PATCH 17/21] linux-user/s390x: " Richard Henderson
2021-06-16 16:52 ` Philippe Mathieu-Daudé
2021-06-16 1:12 ` [PATCH 18/21] linux-user/sh4: " Richard Henderson
2021-06-16 16:53 ` Philippe Mathieu-Daudé
2021-06-16 1:12 ` [PATCH 19/21] linux-user/sparc: " Richard Henderson
2021-06-16 1:12 ` [PATCH 20/21] linux-user/xtensa: " Richard Henderson
2021-06-16 13:35 ` Max Filippov
2021-06-16 1:12 ` [PATCH 21/21] linux-user: Remove default for TARGET_ARCH_HAS_SIGTRAMP_PAGE Richard Henderson
2021-06-16 16:54 ` Philippe Mathieu-Daudé
2021-06-16 15:05 ` Alex Bennée [this message]
2021-06-16 15:09 ` [PATCH 00/21] linux-user: Move signal trampolines to new page Richard Henderson
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