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

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Message-ID: <4EA3EF29-6D79-4F79-B1AD-0B6C12A5FF97@fb.com>
Date:   Wed, 3 Apr 2019 17:05:02 +0000
From:   Song Liu <songliubraving@...com>
To:     Jiri Olsa <jolsa@...hat.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 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

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,