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

On 3 May 2018 at 09:18, Leo Yan leo.yan@linaro.org wrote:

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

tools/perf/util/cs-etm.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c index 6533b1a..417302c 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);
  

} @@ -266,6 +267,7 @@ static u32 cs_etm__mem_access(struct cs_etm_queue *etmq, u64 address, if (!thread) { if (cpumode != PERF_RECORD_MISC_KERNEL) return -EINVAL;

Extra line, please remove.

With this change:

Acked-by: Mathieu Poirier mathieu.poirier@linaro.org

            thread = etmq->etm->unknown_thread;
    }

@@ -1355,6 +1357,23 @@ 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 +1388,18 @@ 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