[PATCH v2 1/2] perf cs-etm: Support unknown_thread in cs_etm_auxtrace

Leo Yan
2018-05-09T04:15:11Z

CoreSight doesn't allocate thread structure for unknown_thread in etm
auxtrace, so unknown_thread is NULL pointer. If the perf data doesn't
contain valid tid and then cs_etm__mem_access() uses unknown_thread
instead as thread handler, this results in segmentation fault when
thread__find_addr_map() accesses thread handler.

This commit creates new thread data which is used by unknown_thread, so
CoreSight tracing can roll back to use unknown_thread if perf data
doesn't include valid thread info. This commit also releases thread
data for initialization failure case and for normal auxtrace free flow.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
tools/perf/util/cs-etm.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 6533b1a..69f21de 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -239,6 +239,7 @@ static void cs_etm__free(struct perf_session *session)
for (i = 0; i < aux->num_cpu; i++)
zfree(&aux->metadata[i]);

+ thread__zput(aux->unknown_thread);
zfree(&aux->metadata);
zfree(&aux);
}
@@ -1355,6 +1356,23 @@ int cs_etm__process_auxtrace_info(union perf_event *event,
etm->auxtrace.free = cs_etm__free;
session->auxtrace = &etm->auxtrace;

+ etm->unknown_thread = thread__new(999999999, 999999999);
+ if (!etm->unknown_thread)
+ goto err_free_queues;
+
+ /*
+ * Initialize list node so that at thread__zput() we can avoid
+ * segmentation fault at list_del_init().
+ */
+ INIT_LIST_HEAD(&etm->unknown_thread->node);
+
+ err = thread__set_comm(etm->unknown_thread, "unknown", 0);
+ if (err)
+ goto err_delete_thread;
+
+ if (thread__init_map_groups(etm->unknown_thread, etm->machine))
+ goto err_delete_thread;
+
if (dump_trace) {
cs_etm__print_auxtrace_info(auxtrace_info->priv, num_cpu);
return 0;
@@ -1369,16 +1387,18 @@ int cs_etm__process_auxtrace_info(union perf_event *event,

err = cs_etm__synth_events(etm, session);
if (err)
- goto err_free_queues;
+ goto err_delete_thread;

err = auxtrace_queues__process_index(&etm->queues, session);
if (err)
- goto err_free_queues;
+ goto err_delete_thread;

etm->data_queued = etm->queues.populated;

return 0;

+err_delete_thread:
+ thread__zput(etm->unknown_thread);
err_free_queues:
auxtrace_queues__free(&etm->queues);
session->auxtrace = NULL;
--
2.7.4