From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752279AbdLLP1a (ORCPT <rfc822;w@1wt.eu>);
        Tue, 12 Dec 2017 10:27:30 -0500
Received: from mail.kernel.org ([198.145.29.99]:41090 "EHLO mail.kernel.org"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751653AbdLLP11 (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 12 Dec 2017 10:27:27 -0500
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C723F20740
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org
Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=acme@kernel.org
Date: Tue, 12 Dec 2017 12:27:24 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: bhargavb <bhargavaramudu@gmail.com>, linux-kernel@vger.kernel.org,
        Paul Clarke <pc@us.ibm.com>,
        Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>,
        Thomas Richter <tmricht@linux.vnet.ibm.com>,
        linux-rt-users@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v4] perf-probe: Support escaped character in parser
Message-ID: <20171212152724.GO3958@kernel.org>
References: <151309111236.18107.5634753157435343410.stgit@devbox>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <151309111236.18107.5634753157435343410.stgit@devbox>
X-Url: http://acmel.wordpress.com
User-Agent: Mutt/1.9.1 (2017-09-22)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Em Wed, Dec 13, 2017 at 12:05:12AM +0900, Masami Hiramatsu escreveu:
> Support the special characters escaped by '\' in parser.
> This allows user to specify versions directly like below.
> 
>   =====
>   # ./perf probe -x /lib64/libc-2.25.so malloc_get_state\\@GLIBC_2.2.5
>   Added new event:
>     probe_libc:malloc_get_state (on malloc_get_state@GLIBC_2.2.5 in /usr/lib64/libc-2.25.so)
> 
>   You can now use it in all perf tools, such as:
> 
> 	  perf record -e probe_libc:malloc_get_state -aR sleep 1
> 
>   =====
> 
> Or, you can use separators in source filename, e.g.
> 
>   =====
>   # ./perf probe -x /opt/test/a.out foo+bar.c:3
>   Semantic error :There is non-digit character in offset.
>     Error: Command Parse Error.
>   =====
> 
> Usually "+" in source file cause parser error, but
> 
>   =====
>   # ./perf probe -x /opt/test/a.out foo\\+bar.c:4
>   Added new event:
>     probe_a:main         (on @foo+bar.c:4 in /opt/test/a.out)
> 
>   You can now use it in all perf tools, such as:
> 
> 	  perf record -e probe_a:main -aR sleep 1
>   =====
> 
> escaped "\+" allows you to specify that.

<SNIP>
 
>  Changes in v4:
>   - Fix a build error (Thanks for Arnaldo!)
>     This time, I ensured that I ran "make build-test" and it passed.

Thanks, testing it I still have that artifact:

 ---------------------------------------

[root@jouet perf]# perf probe -x /lib64/libc-2.25.so malloc_get_state\\@GLIBC_2.2.5
Added new event:
  probe_libc:malloc_get_state (on malloc_get_state@GLIBC_2.2.5 in /usr/lib64/libc-2.25.so)

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

	perf record -e probe_libc:malloc_get_state -aR sleep 1

[root@jouet perf]# perf probe -l
Failed to find debug information for address dd38eca7
  probe_libc:malloc_get_state (on 0xdd38eca7 in /usr/lib64/libc-2.25.so)
[root@jouet perf]#

 ---------------------------------------

I mean the "on 0xdd38eca7" part:


That failed to find debug information part:

[root@jouet perf]# perf probe -vv -l
Add filter: *
Opening /sys/kernel/debug/tracing//kprobe_events write=0
Opening /sys/kernel/debug/tracing//uprobe_events write=0
Parsing probe_events: p:probe_libc/malloc_get_state /usr/lib64/libc-2.25.so:0x00000000dd38eca7
Group:probe_libc Event:malloc_get_state probe:p
try to find information at dd38eca7 in /usr/lib64/libc-2.25.so
Open Debuginfo file: /usr/lib/debug/usr/lib64/libc-2.25.so.debug
Failed to find debug information for address dd38eca7
Failed to find corresponding probes from debuginfo.
symsrc__init: build id mismatch for /usr/lib/debug/usr/lib64/libc-2.25.so.debug.
Failed to find probe point from both of dwarf and map.
  probe_libc:malloc_get_state (on 0xdd38eca7 in /usr/lib64/libc-2.25.so)
[root@jouet perf]#

Ok, so build-id mismatch, lets see:

[root@jouet perf]# rpm -q glibc glibc-debuginfo
glibc-2.25-10.fc26.x86_64
glibc-2.25-10.fc26.i686
glibc-debuginfo-2.25-12.fc26.x86_64
[root@jouet perf]#

Ok, the debuginfo file is newer than the glibc installed, updating glibc
now...

We could have a more informative message in this case, right? I.e.
something like:

[root@jouet perf]# perf probe -l
There was a build-id mismatch while trying to resolve 0xdd38eca7, please
check your system's debuginfo files for mismatches, e.g. check the
versions for glibc and glibc-debuginfo.
  probe_libc:malloc_get_state (on 0xdd38eca7 in /usr/lib64/libc-2.25.so)
[root@jouet perf]#

- Arnaldo