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From:   Marco Elver <elver@google.com>
Date:   Thu, 17 Feb 2022 17:45:49 +0100
Message-ID: <CANpmjNOO6yxF+xXoatR==uvSaEwsWyZ=n7ExEM_=OJaDYBCeSw@mail.gmail.com>
Subject: Re: [PATCH] perf test: Skip Sigtrap test for arm+aarch64
To:     John Garry <john.garry@huawei.com>
Cc:     peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
        mark.rutland@arm.com, jolsa@kernel.org, namhyung@kernel.org,
        leo.yan@linaro.org, dvyukov@google.com, will@kernel.org,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk
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On Thu, 17 Feb 2022 at 17:28, John Garry <john.garry@huawei.com> wrote:
>
> Skip the Sigtrap test for arm + arm64, same as was done for s390 in
> commit a840974e96fd ("perf test: Test 73 Sig_trap fails on s390").
>
> As described by Will at [0], in the test we get stuck in a loop of handling
> the HW breakpoint exception and never making progress. GDB handles this
> by stepping over the faulting instruction, but with perf the kernel is
> expected to handle the step (which it doesn't for arm).
>
> Dmitry made an attempt to get this work, also mentioned in the same thread
> as [0], which was appreciated. But the best thing to do is skip the test
> for now.
>
> [0] https://lore.kernel.org/linux-perf-users/20220118124343.GC98966@leoy-ThinkPad-X240s/T/#m13b06c39d2a5100d340f009435df6f4d8ee57b5a
>
> Fixes: Fixes: 5504f67944484 ("perf test sigtrap: Add basic stress test for sigtrap handling")
> Signed-off-by: John Garry <john.garry@huawei.com>
>
> diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> index 1f147fe6595f..3f0b5c1398b5 100644
> --- a/tools/perf/tests/sigtrap.c
> +++ b/tools/perf/tests/sigtrap.c
> @@ -29,7 +29,8 @@
>   * Just disable the test for these architectures until these issues are
>   * resolved.
>   */
> -#if defined(__powerpc__) || defined(__s390x__)
> +#if defined(__powerpc__) || defined(__s390x__) || \
> +       defined(__arm__) || defined(__aarch64__)
>  #define BP_ACCOUNT_IS_SUPPORTED 0
>  #else
>  #define BP_ACCOUNT_IS_SUPPORTED 1

This is now equivalent to BP_SIGNAL_IS_SUPPORTED
tools/perf/tests/tests.h -- and different from the original
BP_ACCOUNT_IS_SUPPORTED (and makes me wonder why
BP_SIGNAL_IS_SUPPORTED wasn't just used from the beginning). Perhaps
just use BP_SIGNAL_IS_SUPPORTED.

Thanks,
-- Marco