linux-kernel - Re: [PATCH v3] tools lib traceevent: add checks for returned EVENT

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Date:	Fri, 21 Aug 2015 16:03:10 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Arnaldo Carvalho dn Melo <acme@...nel.org>
Cc:	Jiri Olsa <jolsa@...nel.org>, Dean Nelson <dnelson@...hat.com>,
	a.p.zijlstra@...llo.org, mingo@...hat.com, rostedt@...dmis.org,
	namhyung@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] tools lib traceevent: add checks for returned
 EVENT_ERROR type

On Fri, Aug 21, 2015 at 10:34:41AM -0300, Arnaldo Carvalho dn Melo wrote:
> Em Thu, Aug 20, 2015 at 11:16:32AM -0400, Dean Nelson escreveu:
> > Running the following perf-stat command on an arm64 system produces the
> > following result...
>  
> >   [root@...ch64 ~]# perf stat -e kmem:mm_page_alloc -a sleep 1
> >     Warning: [kmem:mm_page_alloc] function sizeof not defined
> >     Warning: Error: expected type 4 but read 0
> >   Segmentation fault
> >   [root@...ch64 ~]#
> 
> Jiri, while testing this I noticed that when running as !root I get:
> 
>   $ perf stat -e kmem:mm_page_alloc -a sleep 1
>   event syntax error: 'kmem:mm_page_alloc'
>                        \___ unknown tracepoint
>   Run 'perf list' for a list of valid events

yep, we need to hook it in.. I recall we discussed this already ;-)
so would something like this be ok:

  $ perf stat -e kmem:mm_page_alloc -a sleep 1
  event syntax error: 'kmem:mm_page_alloc'
                       \___ No permissions to read
  /sys/kernel/debug/tracing/events/raw_syscalls/sys_(enter|exit)
  Hint:       Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
  Run 'perf list' for a list of valid events

jirka
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