perf intel-pt: Fix corrupt data after perf inject from

Commit 59c81482bad671f7 ("perf tools: Add hw_idx in struct branch_stack")
changed the format of branch stacks in perf samples. When samples use
this new format, a flag must be set in the corresponding event.

Synthesized branch stacks generated from Intel PT were using the new
format, but not setting the event attribute, leading to consumers
seeing corrupt data. This patch fixes the issue by setting the event
attribute to indicate use of the new format.

Fixes: 59c81482bad671f7 ("perf tools: Add hw_idx in struct branch_stack")
Signed-off-by: Al Grant <al.grant@arm.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20200819084751.17686-2-leo.yan@linaro.org
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 2a8d245351e747188c690193a5b6f61ca2e99fed..0af4e81c46e2bea4f4698da74c5774be79b62708 100644 (file)
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -3017,8 +3017,15 @@ static int intel_pt_synth_events(struct intel_pt *pt,
 
        if (pt->synth_opts.callchain)
                attr.sample_type |= PERF_SAMPLE_CALLCHAIN;
-       if (pt->synth_opts.last_branch)
+       if (pt->synth_opts.last_branch) {
                attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+               /*
+                * We don't use the hardware index, but the sample generation
+                * code uses the new format branch_stack with this field,
+                * so the event attributes must indicate that it's present.
+                */
+               attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+       }
 
        if (pt->synth_opts.instructions) {
                attr.config = PERF_COUNT_HW_INSTRUCTIONS;