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    Subject[PATCH 4.19 258/280] perf intel-pt: Fix divide by zero when TSC is not available
    Date
    4.19-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Adrian Hunter <adrian.hunter@intel.com>

    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>

    ---
    tools/perf/util/intel-pt.c | 2 ++
    1 file changed, 2 insertions(+)

    --- a/tools/perf/util/intel-pt.c
    +++ b/tools/perf/util/intel-pt.c
    @@ -2507,6 +2507,8 @@ int intel_pt_process_auxtrace_info(union
    }

    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;

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