perf intel-pt: Fix divide by zero when TSC is not available

commit 076333870c2f5bdd9b6d31e7ca1909cf0c84cbfa upstream.

When TSC is not available, "timeless" decoding is used but a divide by
zero occurs if perf_time_to_tsc() is called.

Ensure the divisor is not zero.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org # v4.9+
Link: https://lkml.kernel.org/n/tip-1i4j0wqoc8vlbkcizqqxpsf4@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 2e72373ec6df653a88c7bb3413d37a3c2053ae02..4493fc13a6fafca9ae833fa9d3d0d7ba76e2d490 100644 (file)
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -2522,6 +2522,8 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
        }
 
        pt->timeless_decoding = intel_pt_timeless_decoding(pt);
+       if (pt->timeless_decoding && !pt->tc.time_mult)
+               pt->tc.time_mult = 1;
        pt->have_tsc = intel_pt_have_tsc(pt);
        pt->sampling_mode = false;
        pt->est_tsc = !pt->timeless_decoding;