Re: [PATCH v2 3/3] selftest/bpf: Test a perf bpf program that suppresses side effects.

[Yonghong Song <yonghong.song@linux.dev>]

On 12/7/23 5:08 PM, Kyle Huey wrote:
> On Thu, Dec 7, 2023 at 2:56 PM Kyle Huey <me@kylehuey.com> wrote:
>> On Thu, Dec 7, 2023 at 11:20 AM Marco Elver <elver@google.com> wrote:
>>> On Thu, 7 Dec 2023 at 20:12, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
>>>> On Thu, Dec 7, 2023 at 8:35 AM Kyle Huey <me@kylehuey.com> wrote:
>>>>> The test sets a hardware breakpoint and uses a bpf program to suppress the
>>>>> side effects of a perf event sample, including I/O availability signals,
>>>>> SIGTRAPs, and decrementing the event counter limit, if the ip matches the
>>>>> expected value. Then the function with the breakpoint is executed multiple
>>>>> times to test that all effects behave as expected.
>>>>>
>>>>> Signed-off-by: Kyle Huey <khuey@kylehuey.com>
>>>>> ---
>>>>>   .../selftests/bpf/prog_tests/perf_skip.c      | 145 ++++++++++++++++++
>>>>>   .../selftests/bpf/progs/test_perf_skip.c      |  15 ++
>>>>>   2 files changed, 160 insertions(+)
>>>>>   create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_skip.c
>>>>>   create mode 100644 tools/testing/selftests/bpf/progs/test_perf_skip.c
>>>>>
>>>>> diff --git a/tools/testing/selftests/bpf/prog_tests/perf_skip.c b/tools/testing/selftests/bpf/prog_tests/perf_skip.c
>>>>> new file mode 100644
>>>>> index 000000000000..f6fa9bfd9efa
>>>>> --- /dev/null
>>>>> +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c
>>>>> @@ -0,0 +1,145 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>> +#define _GNU_SOURCE
>>>>> +
>>>>> +/* We need the latest siginfo from the kernel repo. */
>>>>> +#include <asm/siginfo.h>
>>>> selftests are built with UAPI headers' copies under tools/include, so
>>>> CI did catch a real issue, I think. Try copying
>>>> include/uapi/asm-generic/siginfo.h into
>>>> tools/include/uapi/asm-generic/siginfo.h ?
>>> I believe parts of this were inspired by
>>> tools/testing/selftests/perf_events/sigtrap_threads.c - getting the
>>> kernel headers is allowed, as long as $(KHDR_INCLUDES) is added to
>>> CFLAGS. See tools/testing/selftests/perf_events/Makefile. Not sure
>>> it's appropriate for this test though, if you don't want to add
>>> KHDR_INCLUDES for everything.
>> Yes, that's right. Namhyung's commit message for 91c97b36bd69 leads me
>> to believe that I should copy siginfo.h over into tools/include and
>> fix the perf_events self tests too.
>>
>> - Kyle
> That doesn't really help (though perhaps it should be done anyway so
> the selftests aren't reaching into include/) because the glibc headers
> still redefine a ton of stuff in asm-generic/siginfo.h.

Just for testing purpose, I think you can avoid includeasm/siginfo.h and directly define necessary structures in the C file 
directly, right?

>
> - Kyle