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Subject[tip:perf/urgent] perf intel-pt: Fix segfault tracing transactions
Commit-ID:  1342e0b7a6c1a060c593037fbac9f4b717f1cb3b
Gitweb: http://git.kernel.org/tip/1342e0b7a6c1a060c593037fbac9f4b717f1cb3b
Author: Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Mon, 18 Apr 2016 13:57:48 +0300
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 18 Apr 2016 11:00:56 -0300

perf intel-pt: Fix segfault tracing transactions

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>
Cc: stable@vger.kernel.org # v4.4+
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>
---
tools/perf/util/intel-pt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 407f11b..6175784 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1130,7 +1130,7 @@ static int intel_pt_synth_transaction_sample(struct intel_pt_queue *ptq)
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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