| From | Adrian Hunter <> | Subject | [PATCH 01/52] perf tools: Fix jump label always changing during tracing | Date | Tue, 22 Jul 2014 16:17:10 +0300 |
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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> --- 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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