perf cs-etm: 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 CoreSight ETM trace 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>
Reviewed-by: Andrea Brunato <andrea.brunato@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
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: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
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
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Link: http://lore.kernel.org/lkml/20200819084751.17686-1-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index c283223fb31f22479ecfa9e46cdc888c902025c4..a2a369e2fbb67eadbf1474d87a1b55e335bb0f8b 100644 (file)
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1344,8 +1344,15 @@ static int cs_etm__synth_events(struct cs_etm_auxtrace *etm,
                attr.sample_type &= ~(u64)PERF_SAMPLE_ADDR;
        }
 
-       if (etm->synth_opts.last_branch)
+       if (etm->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 (etm->synth_opts.instructions) {
                attr.config = PERF_COUNT_HW_INSTRUCTIONS;