Em Tue, Jul 22, 2014 at 04:17:10PM +0300, Adrian Hunter escreveu: > 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.
And it is ok for our purposes, as this code just needs to figure out if PERF_FLAG_FD_CLOEXEC is present, but I wonder when this kind of thing will hit again... Anyway, I'll take this patch. - Arnaldo > Signed-off-by: Adrian Hunter <adrian.hun...@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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
