linux-kernel - Re: [BUG] perf: intel_pt won't display kernel function

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Date:   Wed, 3 Apr 2019 20:10:47 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Song Liu <songliubraving@...com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <andi@...stfloor.org>,
        "acme@...nel.org" <acme@...nel.org>,
        "jolsa@...nel.org" <jolsa@...nel.org>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [BUG] perf: intel_pt won't display kernel function

On Wed, Apr 03, 2019 at 05:05:02PM +0000, Song Liu wrote:
> 
> 
> > On Apr 3, 2019, at 7:37 AM, Jiri Olsa <jolsa@...hat.com> wrote:
> > 
> > hi,
> > perf script --call-trace stop working for me recently,
> > and displays only user space functions
> > 
> > I bisected that to:
> >  7b612e291a5a perf tools: Synthesize PERF_RECORD_* for loaded BPF programs
> > 
> > data from following comands will display user space functions only:
> >  # perf-with-kcore record pt -e intel_pt// -- ls
> >  # perf-with-kcore script pt --call-trace
> 
> Seems the following are ok (upstream as-is)?
> 
> ./perf record -e intel_pt// -- ls
> ./perf script --call-trace

yes, I think it's the --kallsyms otion which is added by
perf-with-kcore that's broken

jirka

> 
> Jiri, could you please verify this? (Sorry I am new to perf-with-kcore). 
> 
> Thanks,
> Song
> 
> > 
> > when I disable the bpf synthesizing (patch below), kernel functions are back
> > 
> > I guess the new events mess up with intel_pt decoder somehow
> > 
> > 
> > thanks,
> > jirka
> > 
> > 
> > ---
> > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > index 4e2d953d4bc5..3daa78bc6549 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -1114,10 +1114,12 @@ static int record__synthesize(struct record *rec, bool tail)
> > 		return err;
> > 	}
> > 
> > +#if 0
> > 	err = perf_event__synthesize_bpf_events(session, process_synthesized_event,
> > 						machine, opts);
> > 	if (err < 0)
> > 		pr_warning("Couldn't synthesize bpf events.\n");
> > +#endif
> > 
> > 	err = __machine__synthesize_threads(machine, tool, &opts->target, rec->evlist->threads,
> > 					    process_synthesized_event, opts->sample_address,
>