From: Arnaldo Carvalho de Melo <acme@redhat.com>

Date: Mon, 3 Jul 2017 17:01:41 -0300

Subject: perf evsel: Set attr.exclude_kernel when probing max attr.precise_ip

Git-commit: 97365e81366f5ca16a9ce66cff4dd4c5b0d9f4db

Patch-mainline: v4.13-rc1

References: bsc#1070010 (git-fixes)

Signed-off-By: Tony Jones <tonyj@suse.de>

​

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>

---

 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 cda44b0e821c..91192415f38d 100644

--- a/tools/perf/util/evsel.c

+++ b/tools/perf/util/evsel.c

@@ -269,6 +269,7 @@ 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;

​

​