On 07/22/2014 05:00 PM, Arnaldo Carvalho de Melo wrote: > 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...
Possibly > > Anyway, I'll take this patch. Thanks! > > - 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/
