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    Subject[PATCH AUTOSEL for 4.9 207/293] perf evsel: Set attr.exclude_kernel when probing max attr.precise_ip
    Date
    From: Arnaldo Carvalho de Melo <acme@redhat.com>

    [ Upstream commit 97365e81366f5ca16a9ce66cff4dd4c5b0d9f4db ]

    We should set attr.exclude_kernel when probing for attr.precise_ip
    level, otherwise !CAP_SYS_ADMIN users will not default to skidless
    samples in capable hardware.

    The increase in the paranoid level in commit 0161028b7c8a ("perf/core:
    Change the default paranoia level to 2") broke this, fix it by excluding
    kernel samples when probing.

    Before:

    $ perf record usleep 1
    [ perf record: Woken up 1 times to write data ]
    [ perf record: Captured and wrote 0.018 MB perf.data (6 samples) ]
    $ perf evlist -v
    cycles:u: sample_freq: 4000, sample_type: IP|TID|TIME|PERIOD, exclude_kernel: 1

    After:

    $ perf record usleep 1
    [ perf record: Woken up 1 times to write data ]
    [ perf record: Captured and wrote 0.018 MB perf.data (8 samples) ]
    $ perf evlist -v
    cycles:ppp: sample_freq: 4000, sample_type: IP|TID|TIME|PERIOD, exclude_kernel: 1, precise_ip: 3
    ^^^^^^^^^^^^^
    ^^^^^^^^^^^^^
    ^^^^^^^^^^^^^
    $

    To further clarify: we always set .exclude_kernel when non !CAP_SYS_ADMIN
    users profile, its just on the attr.precise_ip probing that we weren't doing
    so, fix it.

    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Wang Nan <wangnan0@huawei.com>
    Fixes: 7f8d1ade1b19 ("perf tools: By default use the most precise "cycles" hw counter available")
    Link: http://lkml.kernel.org/n/tip-t2qttwhbnua62o5gt75cueml@git.kernel.org
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    ---
    tools/perf/util/evsel.c | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
    index 97fe0c80ff02..1c1291afd6a6 100644
    --- a/tools/perf/util/evsel.c
    +++ b/tools/perf/util/evsel.c
    @@ -258,6 +258,7 @@ struct perf_evsel *perf_evsel__new_cycles(void)
    struct perf_event_attr attr = {
    .type = PERF_TYPE_HARDWARE,
    .config = PERF_COUNT_HW_CPU_CYCLES,
    + .exclude_kernel = 1,
    };
    struct perf_evsel *evsel;

    --
    2.15.1
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