Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752175AbZLaKga (ORCPT ); Thu, 31 Dec 2009 05:36:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751660AbZLaKga (ORCPT ); Thu, 31 Dec 2009 05:36:30 -0500 Received: from casper.infradead.org ([85.118.1.10]:47563 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751614AbZLaKg3 (ORCPT ); Thu, 31 Dec 2009 05:36:29 -0500 Date: Thu, 31 Dec 2009 08:36:09 -0200 From: Arnaldo Carvalho de Melo To: Xiao Guangrong Cc: "H. Peter Anvin" , James Bottomley , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Paul Mackerras , "Frank Ch. Eigler" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] x86: record relocation offset Message-ID: <20091231103609.GE2384@ghostprotocols.net> References: <1262216506.2749.254.camel@mulgrave.site> <4B3BE63B.70907@zytor.com> <20091231003046.GC2384@ghostprotocols.net> <4B3C13B0.6080600@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B3C13B0.6080600@cn.fujitsu.com> X-Url: http://oops.ghostprotocols.net:81/blog User-Agent: Mutt/1.5.20 (2009-08-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1519 Lines: 45 Em Thu, Dec 31, 2009 at 11:00:00AM +0800, Xiao Guangrong escreveu: > Arnaldo Carvalho de Melo wrote: > > Conclusion: at 'perf record' time store the address of a well know > > symbol (_text) into the perf.data header. Later, at perf report time, if > > using a vmlinux file, calculate the relocation by subtracting the same > > well known symbol from the one stored in the header. > > So no need for ioctl or boot stuff. > I'm little confused, how to get the load symbol address? > It's not a good way, if you get it from '/proc/kallsyms', we can't assume kernel > has this file. Well, then its just a matter of exposing _text as /sys/kernel/sections/.text, as we already have for modules: [acme@ana linux-2.6-tip]$ cat /sys/module/ipv6/sections/.text 0xfa0c2000 Which matches nf_conntrack_ipv6 17548 2 - Live 0xfa147000 ipv6 239420 32 ip6t_REJECT,nf_conntrack_ipv6, Live 0xfa0c2000 [acme@ana linux-2.6-tip]$ But even as a quick transational assist, we can look at kallsyms at 'perf record' time. > > I'll do that tomorrow, if Xiao doesn't beats me to it :-) > Of course, please do if you have a better way :-) I meant, if you didn't write the patch first, while I was sleeping :-) I'll work on it today after some coffee and errands. Best Regards, - Arnaldo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/