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    Subject[PATCH 4.4 083/163] perf intel-pt: Fix segfault tracing transactions
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

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

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

    commit 1342e0b7a6c1a060c593037fbac9f4b717f1cb3b upstream.

    Tracing a workload that uses transactions gave a seg fault as follows:

    perf record -e intel_pt// workload
    perf report
    Program received signal SIGSEGV, Segmentation fault.
    0x000000000054b58c in intel_pt_reset_last_branch_rb (ptq=0x1a36110)
    at util/intel-pt.c:929
    929 ptq->last_branch_rb->nr = 0;
    (gdb) p ptq->last_branch_rb
    $1 = (struct branch_stack *) 0x0
    (gdb) up
    1148 intel_pt_reset_last_branch_rb(ptq);
    (gdb) l
    1143 if (ret)
    1144 pr_err("Intel Processor Trace: failed to deliver transaction event
    1145 ret);
    1146
    1147 if (pt->synth_opts.callchain)
    1148 intel_pt_reset_last_branch_rb(ptq);
    1149
    1150 return ret;
    1151 }
    1152
    (gdb) p pt->synth_opts.callchain
    $2 = true
    (gdb)
    (gdb) bt
    #0 0x000000000054b58c in intel_pt_reset_last_branch_rb (ptq=0x1a36110)
    #1 0x000000000054c1e0 in intel_pt_synth_transaction_sample (ptq=0x1a36110)
    #2 0x000000000054c5b2 in intel_pt_sample (ptq=0x1a36110)

    Caused by checking the 'callchain' flag when it should have been the
    'last_branch' flag. Fix that.

    Reported-by: Andi Kleen <ak@linux.intel.com>
    Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Fixes: f14445ee72c5 ("perf intel-pt: Support generating branch stack")
    Link: http://lkml.kernel.org/r/1460977068-11566-1-git-send-email-adrian.hunter@intel.com
    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, 1 insertion(+), 1 deletion(-)

    --- a/tools/perf/util/intel-pt.c
    +++ b/tools/perf/util/intel-pt.c
    @@ -1127,7 +1127,7 @@ static int intel_pt_synth_transaction_sa
    pr_err("Intel Processor Trace: failed to deliver transaction event, error %d\n",
    ret);

    - if (pt->synth_opts.callchain)
    + if (pt->synth_opts.last_branch)
    intel_pt_reset_last_branch_rb(ptq);

    return ret;

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