linux-kernel - Re: [PATCH] perf, tools: Handle events including .c and .o

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Date:   Sun, 18 Sep 2016 18:20:04 +0800
From:   "Wangnan (F)" <wangnan0@...wei.com>
To:     Andi Kleen <andi@...stfloor.org>, <acme@...nel.org>
CC:     <jolsa@...nel.org>, <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>, <sukadev@...ux.vnet.ibm.com>
Subject: Re: [PATCH] perf, tools: Handle events including .c and .o



On 2016/9/18 9:02, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
>
> This is a generic bug fix, but it helps with Sukadev's JSON event tree
> where such events can happen.
>
> Any event inclduing a .c/.o/.bpf currently triggers BPF compilation or loading
> and then an error.  This can happen for some Intel JSON events, which cannot
> be used.
>
> Fix the scanner to only match for .o or .c or .bpf at the end.
> This will prevent loading multiple BPF scripts separated with comma,
> but I assume this is acceptable.
>
> Cc: wangnan0@...wei.com
> Cc: sukadev@...ux.vnet.ibm.com
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>

I tested '.c' in middle of an event:

  # perf trace --event 'aaa.ccc'
  invalid or unsupported event: 'aaa.ccc'
  Run 'perf list' for a list of valid events
  ...

It is not recongnized as a BPF source.

So could you please provide an example to show how
this potential bug breaks the parsing of new events?

> ---
>   tools/perf/util/parse-events.l | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 7a2519435da0..64ca26e4ed2d 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -162,8 +162,8 @@ modifier_bp	[rwx]{1,3}
>   		}
>   
>   {event_pmu}	|
> -{bpf_object}	|
> -{bpf_source}	|
> +({bpf_object}$)	|
> +({bpf_source}$)	|

What about putting '$' at the definition of bpf_xxx like this?

diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 9f43fda..d9ff690 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -136,8 +136,8 @@ do 
{                                                        \
  group          [^,{}/]*[{][^}]*[}][^,{}/]*
  event_pmu      [^,{}/]+[/][^/]*[/][^,{}/]*
  event          [^,{}/]+
-bpf_object     .*\.(o|bpf)
-bpf_source     .*\.c
+bpf_object     .*\.(o|bpf)$
+bpf_source     .*\.c$

  num_dec                [0-9]+
  num_hex                0x[a-fA-F0-9]+

Thank you.

>   {event}		{
>   			BEGIN(INITIAL);
>   			REWIND(1);