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Commit 46ec69ad authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
Browse files

perf tools: Fix probing the kernel API with cpu-wide events 



Fall back to probing with the current pid if cpu-wide probing fails.
This primarily affects the setting of comm_exec flag when the user is
un-privileged and /proc/sys/kernel/perf_event_paranoid > 0.

The change to comm_exec can be observed by using -vv with perf record
and a kernel that supports comm_exec.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1407855871-15024-4-git-send-email-adrian.hunter@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c6fa3565

tools/perf/util/record.c

+27 −9
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ static int perf_do_probe_api(setup_probe_fn_t fn, int cpu, const char *str) 
	struct perf_evsel *evsel;

	unsigned long flags = perf_event_open_cloexec_flag();

	int err = -EAGAIN, fd;

	static pid_t pid = -1;



	evlist = perf_evlist__new();

	if (!evlist)
@@ -24,14 +25,22 @@ static int perf_do_probe_api(setup_probe_fn_t fn, int cpu, const char *str) 


	evsel = perf_evlist__first(evlist);



	fd = sys_perf_event_open(&evsel->attr, -1, cpu, -1, flags);

	if (fd < 0)

	while (1) {

		fd = sys_perf_event_open(&evsel->attr, pid, cpu, -1, flags);

		if (fd < 0) {

			if (pid == -1 && errno == EACCES) {

				pid = 0;

				continue;

			}

			goto out_delete;

		}

		break;

	}

	close(fd);



	fn(evsel);



	fd = sys_perf_event_open(&evsel->attr, -1, cpu, -1, flags);

	fd = sys_perf_event_open(&evsel->attr, pid, cpu, -1, flags);

	if (fd < 0) {

		if (errno == EINVAL)

			err = -EINVAL;
@@ -201,6 +210,7 @@ bool perf_evlist__can_select_event(struct perf_evlist *evlist, const char *str) 
	struct perf_evsel *evsel;

	int err, fd, cpu;

	bool ret = false;

	pid_t pid = -1;



	temp_evlist = perf_evlist__new();

	if (!temp_evlist)
@@ -221,12 +231,20 @@ bool perf_evlist__can_select_event(struct perf_evlist *evlist, const char *str) 
		cpu = evlist->cpus->map[0];

	}



	fd = sys_perf_event_open(&evsel->attr, -1, cpu, -1,

	while (1) {

		fd = sys_perf_event_open(&evsel->attr, pid, cpu, -1,

					 perf_event_open_cloexec_flag());

	if (fd >= 0) {

		if (fd < 0) {

			if (pid == -1 && errno == EACCES) {

				pid = 0;

				continue;

			}

			goto out_delete;

		}

		break;

	}

	close(fd);

	ret = true;

	}



out_delete:

	perf_evlist__delete(temp_evlist);