Re: [PATCH] perf: cs-etm: Fix the assert() to handle captured and unprocessed cpu trace

From: James Clark
Date: Wed Sep 25 2024 - 05:54:44 EST




On 25/09/2024 12:39 am, Ilkka Koskinen wrote:
If one builds perf with DEBUG=1, captures data on multiple CPUs and
finally runs 'perf report -C <cpu>' for only one of the cpus, assert()
aborts the program. This happens because there are empty queues with
format set. This patch changes the condition to abort only if a queue
is not empty and if the format is unset.

$ make -C tools/perf DEBUG=1 CORESIGHT=1 CSLIBS=/usr/lib CSINCLUDES=/usr/include install
$ perf record -o kcore --kcore -e cs_etm/timestamp/k -s -C 0-1 dd if=/dev/zero of=/dev/null bs=1M count=1
$ perf report --input kcore/data --vmlinux=/home/ikoskine/projects/linux/vmlinux -C 1
Aborted (core dumped)

Fixes: 57880a7966be ("perf: cs-etm: Allocate queues for all CPUs")
Signed-off-by: Ilkka Koskinen <ilkka@xxxxxxxxxxxxxxxxxxxxxx>
---
tools/perf/util/cs-etm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 90f32f327b9b..40f047baef81 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -3323,7 +3323,7 @@ static int cs_etm__create_decoders(struct cs_etm_auxtrace *etm)
* Don't create decoders for empty queues, mainly because
* etmq->format is unknown for empty queues.
*/
- assert(empty == (etmq->format == UNSET));
+ assert(empty || etmq->format != UNSET);
if (empty)
continue;

Oops I didn't realize you could filter on CPU in report mode. Thanks for the fix. Adding a test to the end of test_arm_coresight.sh might be quite useful. Either way:

Reviewed-by: James Clark <james.clark@xxxxxxxxxx>