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authorVince Weaver <vincent.weaver@maine.edu>2013-12-30 15:39:45 -0500
committerArnaldo Carvalho de Melo <acme@redhat.com>2014-02-10 11:34:31 -0300
commit88fee52e58ca14d8465b614774ed0bf08e1a7790 (patch)
treed0043a4b7886fdfa76ed6bc0d95e24df2b03e079 /tools
parentf67697bd079f4bbcbe7d6d26765a06b18afe0630 (diff)
perf list: Fix checking for supported events on older kernels
"perf list" listing of hardware events doesn't work on older ARM devices. The change enabling event detection: commit b41f1cec91c37eeea6fdb15effbfa24ea0a5536b Author: Namhyung Kim <namhyung.kim@lge.com> Date: Tue Aug 27 11:41:53 2013 +0900 perf list: Skip unsupported events uses the following code in tools/perf/util/parse-events.c: struct perf_event_attr attr = { .type = type, .config = config, .disabled = 1, .exclude_kernel = 1, }; On ARM machines pre-dating the Cortex-A15 this doesn't work, as these machines don't support .exclude_kernel. So starting with 3.12 "perf list" does not report any hardware events at all on older machines (seen on Rasp-Pi, Pandaboard, Beagleboard, etc). This version of the patch makes changes suggested by Namhyung Kim to check for EACCESS and retry (instead of just dropping the exclude_kernel) so we can properly handle machines where /proc/sys/kernel/perf_event_paranoid is set to 2. Reported-by: Chad Paradis <chad.paradis@umit.maine.edu> Signed-off-by: Vince Weaver <vincent.weaver@maine.edu> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Chad Paradis <chad.paradis@umit.maine.edu> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1312301536150.28814@vincent-weaver-1.um.maine.edu Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/util/parse-events.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index d248fca6d7ed..1e15df10a88c 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1091,12 +1091,12 @@ int is_valid_tracepoint(const char *event_string)
static bool is_event_supported(u8 type, unsigned config)
{
bool ret = true;
+ int open_return;
struct perf_evsel *evsel;
struct perf_event_attr attr = {
.type = type,
.config = config,
.disabled = 1,
- .exclude_kernel = 1,
};
struct {
struct thread_map map;
@@ -1108,7 +1108,20 @@ static bool is_event_supported(u8 type, unsigned config)
evsel = perf_evsel__new(&attr);
if (evsel) {
- ret = perf_evsel__open(evsel, NULL, &tmap.map) >= 0;
+ open_return = perf_evsel__open(evsel, NULL, &tmap.map);
+ ret = open_return >= 0;
+
+ if (open_return == -EACCES) {
+ /*
+ * This happens if the paranoid value
+ * /proc/sys/kernel/perf_event_paranoid is set to 2
+ * Re-run with exclude_kernel set; we don't do that
+ * by default as some ARM machines do not support it.
+ *
+ */
+ evsel->attr.exclude_kernel = 1;
+ ret = perf_evsel__open(evsel, NULL, &tmap.map) >= 0;
+ }
perf_evsel__delete(evsel);
}