linux-kernel - Re: [PATCH -tip ] [BUGFIX] perf probe: Fix to probe on symbols with optimization suffix

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Date:	Wed, 25 Sep 2013 12:38:38 -0300
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc:	Ingo Molnar <mingo@...hat.com>, Paul Mackerras <paulus@...ba.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH -tip ] [BUGFIX] perf probe: Fix to probe on symbols with
 optimization suffix

Em Wed, Sep 25, 2013 at 10:16:16PM +0900, Masami Hiramatsu escreveu:
> Fix perf probe to probe on some symbols which have some
> optimzation suffixes, e.g. ".part", ".isra", and ".constprop".
> To fix this issue, instead of using DIE name, perf probe
> uses symbol name found by dwfl_module_addrsym().

Thanks Masami! Now it behaves _exactly_ as I expected and need:

[root@zoo linux]# perf probe -L getname_flags:65
<getname_flags@...me/git/linux/fs/namei.c:65>
     65         result->uptr = filename;
     66         audit_getname(result);
                return result;
         
         error:
     70         final_putname(result);
     71         return err;
     72  }
         
         struct filename *
         getname(const char __user * filename)

[root@zoo linux]# perf probe -V getname_flags:65
Available variables at getname_flags:65
        @<getname_flags.part.35+178>
                char*   filename
                int*    empty
                long int        max
                struct filename*        result
[root@zoo linux]# perf probe 'getname_flags:66 pathname=result->name:string'
Added new event:
  probe:getname_flags  (on getname_flags:66 with pathname=result->name:string)

You can now use it in all perf tools, such as:

	perf record -e probe:getname_flags -aR sleep 1

[root@zoo linux]# perf record -a -e probe:getname_flags
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 1.252 MB perf.data (~54692 samples) ]
[root@zoo linux]# perf script | grep -v '# | head -5
> ^C
[root@zoo linux]# perf script | grep -v '^#' | head -5
        libvirtd  1163 [001] 100606.469450: probe:getname_flags: (ffffffff811a2f89) pathname="/proc/cpuinfo"
        libvirtd  1163 [001] 100606.469563: probe:getname_flags: (ffffffff811a2f89) pathname="/sys/devices/system/node"
        libvirtd  1163 [001] 100606.469596: probe:getname_flags: (ffffffff811a2f89) pathname="/sys/devices/system/node/node0"
        libvirtd  1163 [001] 100606.469612: probe:getname_flags: (ffffffff811a2f89) pathname="/sys/devices/system/node/node0/cpu0/online"
        libvirtd  1163 [001] 100606.469628: probe:getname_flags: (ffffffff811a2f89) pathname="/sys/devices/system/node/node0/cpu0/topology/physical_package_id"
[root@zoo linux]#

Thanks a lot, applied to my perf/urgent branch,

- Arnaldo
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