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

From: Leo Yan
Date: Tue May 08 2018 - 21:00:01 EST


On Tue, May 08, 2018 at 11:01:30AM -0600, Mathieu Poirier wrote:
> On 3 May 2018 at 09:18, Leo Yan <leo.yan@xxxxxxxxxx> 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@xxxxxxxxxx>
> > ---
> > 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@xxxxxxxxxx>

Thanks for reviewing, Mathieu. Will spin new patches and send out.

[...]

Thanks,
Leo Yan