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Date:   Fri, 18 Feb 2022 09:56:58 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Leo Yan <leo.yan@linaro.org>
Cc:     John Garry <john.garry@huawei.com>, peterz@infradead.org,
        mingo@redhat.com, mark.rutland@arm.com, jolsa@kernel.org,
        namhyung@kernel.org, elver@google.com, 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, tmricht@linux.ibm.com, irogers@google.com
Subject: Re: [PATCH v2] perf test: Skip Sigtrap test for arm+aarch64
Message-ID: <Yg+Xmt27POS2y2LI@kernel.org>
References: <1645176813-202756-1-git-send-email-john.garry@huawei.com>
 <20220218104611.GD56419@leoy-ThinkPad-X240s>
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Em Fri, Feb 18, 2022 at 06:46:11PM +0800, Leo Yan escreveu:
> On Fri, Feb 18, 2022 at 05:33:33PM +0800, John Garry 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"). For
> > this, reuse BP_SIGNAL_IS_SUPPORTED - meaning that the arch can use BP to
> > generate signals - instead of BP_ACCOUNT_IS_SUPPORTED, which is
> > appropriate.
> > 
> > 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>
> 
> I tested this patch on my Juno board:
> 
> root@Juno:# ./perf test 73
>  73: Sigtrap                                                         : Skip
> 
> Tested-by: Leo Yan <leo.yan@linaro.org>

Thanks, applied.

- Arnaldo