Commit deaff8b6 authored Jul 22, 2014 by Adrian Hunter Committed by Arnaldo Carvalho de Melo Jul 23, 2014

perf tools: Fix jump label always changing during tracing



Intel PT decoding walks the object code to reconstruct the trace.  A
jump label change during tracing causes decoding errors.

The "Enable close-on-exec flag on perf file descriptor" patch caused
there to be always a jump label change.

It was found that using a per-cpu context instead of a per-thread
context for the probe of the close-on-exec feature, made the problem go
away.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
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/1406035081-14301-2-git-send-email-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent a6f6ae99

tools/perf/util/cloexec.c

+7 −2

Original line number	Diff line number	Diff line
		#include <sched.h>
		#include "util.h"
		#include "../perf.h"
		#include "cloexec.h"
		@@ -14,9 +15,13 @@ static int perf_flag_probe(void)
		};
		int fd;
		int err;
		int cpu = sched_getcpu();

		if (cpu < 0)
		cpu = 0;

		/* check cloexec flag */
		fd = sys_perf_event_open(&attr, 0, -1, -1,
		fd = sys_perf_event_open(&attr, -1, cpu, -1,
		PERF_FLAG_FD_CLOEXEC);
		err = errno;

		@@ -30,7 +35,7 @@ static int perf_flag_probe(void)
		err, strerror(err));

		/* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */
		fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
		fd = sys_perf_event_open(&attr, -1, cpu, -1, 0);
		err = errno;

		if (WARN_ONCE(fd < 0,