linux-kernel - Re: [PATCH 05/12] perf pmu: Fix pmu events parsing rule

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Date:   Thu, 3 May 2018 14:38:15 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Jiri Olsa <jolsa@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        David Ahern <dsahern@...il.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 05/12] perf pmu: Fix pmu events parsing rule

On 03/05/18 13:37, Jiri Olsa wrote:
> On Thu, May 03, 2018 at 11:25:16AM +0300, Adrian Hunter wrote:
>> Hi
>>
>> This breaks Intel PT i.e.
>>
>> $ perf record -e intel_pt//u uname
>> event syntax error: 'intel_pt//u'
>>                              \___ parser error
>> Run 'perf list' for a list of valid events
>>
>>  Usage: perf record [<options>] [<command>]
>>     or: perf record [<options>] -- <command> [<options>]
>>
>>     -e, --event <event>   event selector. use 'perf list' to list available events
>>
>> See below for cause.
>>
>> On 25/04/18 19:00, Arnaldo Carvalho de Melo wrote:
>>> From: Jiri Olsa <jolsa@...nel.org>
>>>
>>> Currently all the event parsing fails end up in the event_pmu rule, and
>>> display misleading help like:
>>>
>>>   $ perf stat -e inst kill
>>>   event syntax error: 'inst'
>>>                        \___ Cannot find PMU `inst'. Missing kernel support?
>>>   ...
>>>
>>> The reason is that the event_pmu is too strong and match also single
>>> string. Changing it to force the '/' separators to be part of the rule,
>>> and getting the proper error now:
>>>
>>>   $ perf stat -e inst kill
>>>   event syntax error: 'inst'
>>>                        \___ parser error
>>>   Run 'perf list' for a list of valid events
>>>   ...
>>>
>>> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
>>> Reported-by: Ingo Molnar <mingo@...nel.org>
>>> Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
>>> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
>>> Cc: David Ahern <dsahern@...il.com>
>>> Cc: Namhyung Kim <namhyung@...nel.org>
>>> Cc: Peter Zijlstra <peterz@...radead.org>
>>> Link: http://lkml.kernel.org/r/20180423090823.32309-5-jolsa@kernel.org
>>> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
>>> ---
>>>  tools/perf/util/parse-events.y | 8 ++++----
>>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
>>> index 7afeb80cc39e..d14464c42714 100644
>>> --- a/tools/perf/util/parse-events.y
>>> +++ b/tools/perf/util/parse-events.y
>>> @@ -224,15 +224,15 @@ event_def: event_pmu |
>>>  	   event_bpf_file
>>>  
>>>  event_pmu:
>>> -PE_NAME opt_event_config
>>> +PE_NAME '/' event_config '/'
>>
>> These are not equivalent because opt_event_config allows '//'
>> but event_config cannot be an empty string.
> 
> yep, overlooked this one, how about patch below

Seems to work but gives build warnings:

util/parse-events.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
util/parse-events.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]


> 
> jirka
> 
> ---
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index d14464c42714..1ed2befeca8a 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -523,6 +523,10 @@ event_term
>  	list_add_tail(&term->list, head);
>  	$$ = head;
>  }
> +|
> +{
> +	$$ = NULL;
> +}
>  
>  event_term:
>  PE_NAME '=' PE_NAME
>