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Date: Tue, 22 Jul 2014 16:17:10 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...il.com>,
Paul Mackerras <paulus@...ba.org>,
Stephane Eranian <eranian@...gle.com>
Subject: [PATCH 01/52] 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@...el.com>
---
tools/perf/util/cloexec.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index c5d05ec..6a37be5 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -1,3 +1,4 @@
+#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,
--
1.8.3.2
--
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