linux-kernel - Re: [PATCH] perf tools: Fix ftrace:function event recording

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Date:	Thu, 13 Nov 2014 18:25:07 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Jiri Olsa <jolsa@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH] perf tools: Fix ftrace:function event recording

On Thu, Nov 13, 2014 at 06:21:03PM +0100, Jiri Olsa wrote:
> Following patch fails (-EINVAL) ftrace:function with enabled user
> space callchains:
>   cfa77bc4af2c perf: Disallow user-space callchains for function trace events
> 
> We need to follow in perf tool itself and explicitly set the
> perf_event_attr::exclude_callchain_user flag for ftrace:function
> event.

forgot:

Reported-by: Steven Rostedt <rostedt@...dmis.org>

thanks,
jirka

> 
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
> Cc: David Ahern <dsahern@...il.com>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Paul Mackerras <paulus@...ba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/util/evsel.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index ec5eb8033296..a3baaa31231e 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -658,6 +658,14 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts)
>  		attr->mmap_data = track;
>  	}
>  
> +	/*
> +	 * We don't allow user space callchains for  function trace
> +	 * event, due to issues with page faults while tracing page
> +	 * fault handler and its overall trickiness nature.
> +	 */
> +	if (perf_evsel__is_function_event(evsel))
> +		evsel->attr.exclude_callchain_user = 1;
> +
>  	if (callchain_param.enabled && !evsel->no_aux_samples)
>  		perf_evsel__config_callgraph(evsel);
>  
> -- 
> 1.9.3
> 
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