diff mbox series

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

Message ID 1525924920-4381-1-git-send-email-leo.yan@linaro.org
State Accepted
Commit 46d53620044f7b574c0f3216f8b4f2ce3559ce31
Headers show
Series [RESEND,v2,1/2] perf cs-etm: Support unknown_thread in cs_etm_auxtrace | expand

Commit Message

Leo Yan May 10, 2018, 4:01 a.m. UTC
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(-)

-- 
2.7.4

Comments

Arnaldo Carvalho de Melo May 11, 2018, 1:48 p.m. UTC | #1
Em Thu, May 10, 2018 at 12:01:59PM +0800, Leo Yan escreveu:
> 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>


Thanks, applied to perf/urgent.

And please use a more descriptive, eye catching summary, something like:

  perf cs-etm: Fix segfault when accessing NULL unknown_thread variable

:-)

- Arnaldo
Leo Yan May 11, 2018, 11:29 p.m. UTC | #2
On Fri, May 11, 2018 at 10:48:00AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Thu, May 10, 2018 at 12:01:59PM +0800, Leo Yan escreveu:

> > 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>

> 

> Thanks, applied to perf/urgent.

> 

> And please use a more descriptive, eye catching summary, something like:

> 

>   perf cs-etm: Fix segfault when accessing NULL unknown_thread variable

> 

> :-)


Thanks for suggestion.  Indeed, this patch is a fix rather than
a new feature, subject should reflect it.

Thanks,
Leo Yan
diff mbox series

Patch

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;