Patch "perf cs-etm: Fix corrupt data after perf inject from" has been added to the 5.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    perf cs-etm: Fix corrupt data after perf inject from

to the 5.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-cs-etm-fix-corrupt-data-after-perf-inject-from.patch
and it can be found in the queue-5.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit aa363e1fc121920c7e21a47fa0ee0413bf62d3e5
Author: Al Grant <al.grant@xxxxxxx>
Date:   Wed Aug 19 16:47:50 2020 +0800

    perf cs-etm: Fix corrupt data after perf inject from
    
    [ Upstream commit f5f8e7e55fbdb4fdddec73518e23c48083108fbb ]
    
    Commit 42bbabed09ce6208 ("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: 42bbabed09ce6208 ("perf tools: Add hw_idx in struct branch_stack")
    Signed-off-by: Al Grant <al.grant@xxxxxxx>
    Reviewed-by: Andrea Brunato <andrea.brunato@xxxxxxx>
    Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
    Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
    Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
    Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
    Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
    Cc: Mark Rutland <mark.rutland@xxxxxxx>
    Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
    Cc: Mike Leach <mike.leach@xxxxxxxxxx>
    Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
    Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
    Cc: Suzuki Poulouse <suzuki.poulose@xxxxxxx>
    Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
    Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
    Link: http://lore.kernel.org/lkml/20200819084751.17686-1-leo.yan@xxxxxxxxxx
    Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index c283223fb31f2..a2a369e2fbb67 100644
--- 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;