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

[Leo Yan]

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....@linaro.org>
Acked-by: Mathieu Poirier <mathieu.poir...@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