linux-kernel - Re: [PATCH 1/2] perf cs-etm: Support unknown_thread in cs_etm

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Message-ID: <20180509005640.GB23540@leoy-ThinkPad-X240s>
Date:   Wed, 9 May 2018 08:56:41 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel@...r.kernel.org, coresight@...ts.linaro.org
Subject: Re: [PATCH 1/2] perf cs-etm: Support unknown_thread in
 cs_etm_auxtrace

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

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

[...]

Thanks,
Leo Yan