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From:   John Garry <john.garry@huawei.com>
Subject: Re: [PATCH] perf test: Test 73 Sig_trap fails on s390
To:     Leo Yan <leo.yan@linaro.org>
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        Thomas Richter <tmricht@linux.ibm.com>,
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        Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
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Date:   Tue, 18 Jan 2022 10:20:37 +0000
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Hi Leo,

>> test child forked, pid 45193
> Both Arm and Arm64 platforms cannot support signal handler with
> breakpoint, please see the details in [1].  

Thanks for the info.

>So I think we need
> something like below:
> 

ok

> static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
> {
>          ...
> 
>          if (!BP_SIGNAL_IS_SUPPORTED) {
>                  pr_debug("Test not supported on this architecture");
>                  return TEST_SKIP;
>          }
> 
>          ...
> }
> 
> Since we have defined BP_SIGNAL_IS_SUPPORTED, I think we can reuse it at
> here.


Do you know any other architectures which would have this issue? Or a 
generic way to check for support?

It's better to not have to add to this list arch-by-arch..

> 
> [1]https://lore.kernel.org/lkml/157169993406.29376.12473771029179755767.tip-bot2@tip-bot2/
> 
>> And fails on my x86 broadwell machine:
>>
>> john@localhost:~/kernel-dev2/tools/perf> sudo ./perf test -v 73
>> 73: Sigtrap                                                         :
>> --- start ---
>> test child forked, pid 22255
>> FAILED sys_perf_event_open(): Argument list too long
>> test child finished with -1
>> ---- end ----
>> Sigtrap: FAILED!
>> john@localhost:~/kernel-dev2/tools/perf>
> It is a bit suprise for the failure on x86, as I remembered x86 platform
> can support signal handler with hw breakpoint.  And from the error
> "Argument list too long", it should be a different issue from other
> archs.

Yeah, I don't know what's going on here.

Thanks,
John