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Subject: Re: [PATCH v2] perf test: Skip Sigtrap test for arm+aarch64
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        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
References: <1645176813-202756-1-git-send-email-john.garry@huawei.com>
 <20220218104611.GD56419@leoy-ThinkPad-X240s> <Yg+Xmt27POS2y2LI@kernel.org>
From:   kajoljain <kjain@linux.ibm.com>
Message-ID: <447ebda7-eaff-f765-d6ec-66ad0fc957a0@linux.ibm.com>
Date:   Mon, 21 Feb 2022 15:22:32 +0530
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On 2/18/22 6:26 PM, Arnaldo Carvalho de Melo wrote:
> 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>

Sorry for late update.

Patch looks good to me. I tested it on powerpc.

Tested-by: Kajol Jain<kjain@linux.ibm.com>

Thanks,
Kajol Jain
> 
> Thanks, applied.
> 
> - Arnaldo
>