linux-kernel - Re: [PATCH 2/2] perf test: Add perf record sample filtering test

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Date:   Tue, 22 Aug 2023 17:50:26 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Subject: Re: [PATCH 2/2] perf test: Add perf record sample filtering test

Hi Arnaldo,

On Tue, Aug 15, 2023 at 10:42 AM Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
>
> Em Tue, Aug 15, 2023 at 02:30:18PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Thu, Aug 10, 2023 at 07:58:22PM -0700, Namhyung Kim escreveu:
> > >   $ sudo ./perf test 'sample filter' -v
> > >    94: perf record sample filtering (by BPF) tests                     :
> > >   --- start ---
> > >   test child forked, pid 3817527
> > >   Checking BPF-filter privilege
> > >   Basic bpf-filter test
> > >   Basic bpf-filter test [Success]
> > >   Failing bpf-filter test
> > >   Error: task-clock event does not have PERF_SAMPLE_CPU
> > >   Failing bpf-filter test [Success]
> > >   Group bpf-filter test
> > >   Error: task-clock event does not have PERF_SAMPLE_CPU
> > >   Error: task-clock event does not have PERF_SAMPLE_CODE_PAGE_SIZE
> > >   Group bpf-filter test [Success]
> > >   test child finished with 0
> > >   ---- end ----
> > >   perf record sample filtering (by BPF) tests: Ok
> >
> > [root@...e ~]# perf test -v "by BPF"
> >  91: perf record sample filtering (by BPF) tests                     :
> > --- start ---
> > test child forked, pid 64165
> > Checking BPF-filter privilege
> > Basic bpf-filter test
> >  ffffffff97f4f688
> >  ffffffff97f73859
> >  ffffffff97412ce6
> >  ffffffff976da215
> >  ffffffff973a92bf
> >  ffffffff97376ad7
> >  ffffffff97f73859
> <SNIP
> >  ffffffff971fdca5
> >  ffffffff9737dbc4
> >  ffffffff971b4e04
> > Basic bpf-filter test [Failed invalid output]
> > test child finished with -1
> > ---- end ----
> > perf record sample filtering (by BPF) tests: FAILED!
> > [root@...e ~]#
> >
> > [root@...e ~]# uname -a
> > Linux five 6.2.15-100.fc36.x86_64 #1 SMP PREEMPT_DYNAMIC Thu May 11 16:51:53 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
> > [root@...e ~]#
>
> Above was on a AMD Ryzen 5950X, the following was on a lenovo t480s,
> Intel notebook:

Thanks for the test.  I think it's a matter of the kernel version
rather than the CPU vendor.  6.1 or before will fail the check
in the beginning but 6.2 kernel lacks a feature to set sample
flags for some fields and silently accept all samples.  IIRC it's
added in v6.3.

Probably I need to add a version check in the error path.

Thanks,
Namhyung

>
> [root@...co ~]# uname -a
> Linux quaco 6.4.7-200.fc38.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Jul 27 20:01:18 UTC 2023 x86_64 GNU/Linux
> [root@...co ~]# perf test "filter"
>  30: Filter hist entries                                             : Ok
>  36: Filter fds with revents mask in a fdarray                       : Ok
>  67: dlfilter C API                                                  : Ok
>  91: perf record sample filtering (by BPF) tests                     : Ok
> [root@...co ~]# perf test -v "by BPF"
>  91: perf record sample filtering (by BPF) tests                     :
> --- start ---
> test child forked, pid 273609
> Checking BPF-filter privilege
> Basic bpf-filter test
> Basic bpf-filter test [Success]
> Failing bpf-filter test
> Error: task-clock event does not have PERF_SAMPLE_CPU
> Failing bpf-filter test [Success]
> Group bpf-filter test
> Error: task-clock event does not have PERF_SAMPLE_CPU
> Error: task-clock event does not have PERF_SAMPLE_CODE_PAGE_SIZE
> Group bpf-filter test [Success]
> test child finished with 0
> ---- end ----
> perf record sample filtering (by BPF) tests: Ok
> [root@...co ~]#