releases/4.19.31/perf-intel-pt-fix-divide-by-zero-when-tsc-is-not-available.patch

   1 From 076333870c2f5bdd9b6d31e7ca1909cf0c84cbfa Mon Sep 17 00:00:00 2001
   2 From: Adrian Hunter <adrian.hunter@intel.com>
   3 Date: Fri, 1 Mar 2019 12:35:36 +0200
   4 Subject: perf intel-pt: Fix divide by zero when TSC is not available
   5
   6 From: Adrian Hunter <adrian.hunter@intel.com>
   7
   8 commit 076333870c2f5bdd9b6d31e7ca1909cf0c84cbfa upstream.
   9
  10 When TSC is not available, "timeless" decoding is used but a divide by
  11 zero occurs if perf_time_to_tsc() is called.
  12
  13 Ensure the divisor is not zero.
  14
  15 Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
  16 Cc: Jiri Olsa <jolsa@redhat.com>
  17 Cc: stable@vger.kernel.org # v4.9+
  18 Link: https://lkml.kernel.org/n/tip-1i4j0wqoc8vlbkcizqqxpsf4@git.kernel.org
  19 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  tools/perf/util/intel-pt.c |    2 ++
  24  1 file changed, 2 insertions(+)
  25
  26 --- a/tools/perf/util/intel-pt.c
  27 +++ b/tools/perf/util/intel-pt.c
  28 @@ -2507,6 +2507,8 @@ int intel_pt_process_auxtrace_info(union
  29         }
  30
  31         pt->timeless_decoding = intel_pt_timeless_decoding(pt);
  32 +       if (pt->timeless_decoding && !pt->tc.time_mult)
  33 +               pt->tc.time_mult = 1;
  34         pt->have_tsc = intel_pt_have_tsc(pt);
  35         pt->sampling_mode = false;
  36         pt->est_tsc = !pt->timeless_decoding;