From 97365e81366f5ca16a9ce66cff4dd4c5b0d9f4db Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Mon, 3 Jul 2017 17:01:41 -0300 Subject: [PATCH] perf evsel: Set attr.exclude_kernel when probing max attr.precise_ip 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 Cc: Andy Lutomirski Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan 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 --- 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; -- 2.20.1