linux-kernel - Re: BUG: different symbol address between System.map and /proc/kallsyms

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Date:	Sun, 20 Dec 2009 22:31:12 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
CC:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Paul Mackerras <paulus@...ba.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: BUG: different symbol address between System.map and /proc/kallsyms

On 12/20/2009 05:20 PM, Xiao Guangrong wrote:
> Hi,
> 
> The symbol address in System.map and /proc/kallsys is different:
> 
> # cat System.map | grep _text
>   c1000000 T _text
> # cat /proc/kallsyms | grep _text
>   c0100000 T _text
> 
> # readelf -s vmlinux | grep _text
> 35078: c1000000     0 NOTYPE  GLOBAL DEFAULT    1 _text
> 
> So, perf can't get sysmbol address properly:
> 
> # ./perf report
> # Samples: 29
> #
> # Overhead  Command        Shared Object  Symbol
> # ........  .......  ...................  ......
> #
>     93.10%    sleep             c014f988  [k] 0x000000c014f988
>      3.45%    sleep  libc-2.9.90.so       [.] _int_malloc
>      3.45%    sleep  [kernel]             [k] 0x000000c014f988

That is normal if you have a relocatable kernel which has been loaded at
the non-compile-time default address.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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