Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753752AbaBDKFm (ORCPT ); Tue, 4 Feb 2014 05:05:42 -0500 Received: from mail4.hitachi.co.jp ([133.145.228.5]:34211 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079AbaBDKFe (ORCPT ); Tue, 4 Feb 2014 05:05:34 -0500 Message-ID: <52F0BB60.8020402@hitachi.com> Date: Tue, 04 Feb 2014 19:05:20 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Namhyung Kim Cc: Arnaldo Carvalho de Melo , Srikar Dronamraju , David Ahern , linux-kernel@vger.kernel.org, "Steven Rostedt (Red Hat)" , Oleg Nesterov , Ingo Molnar , "David A. Long" , yrl.pp-manager.tt@hitachi.com Subject: Re: Re: Re: [PATCH -tip v2 4/8] perf-probe: Use _stext based address instead of the symbol name References: <20140129091450.22141.86662.stgit@kbuild-fedora.yrl.intra.hitachi.co.jp> <20140129091459.22141.29467.stgit@kbuild-fedora.yrl.intra.hitachi.co.jp> <87d2j43aav.fsf@sejong.aot.lge.com> <52EF541E.8040802@hitachi.com> <52F0B7C5.8080609@hitachi.com> In-Reply-To: <52F0B7C5.8080609@hitachi.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/02/04 18:49), Masami Hiramatsu wrote: >>> Couldn't we just use kmap->ref_reloc_sym instead of the hard-coded >>> "_stext"? You might want to check the Adrian's recent kaslr fixes (now >>> in tip/perf/urgent). >> >> Yeah, I just found Adrian's work and this series must be updated for that, >> because symbol's address is now based on the real (relocated) address. >> OK, I'll try to use a symbol in ref_reloc_sym. ;) Thank you for pointed it out! > > Hmm, I've tested using ref_reloc_sym for new version, setting probes was OK, > but getting the address of "_text" always failed. It seems that the kmaps > doesn't make a symbol for "_text", on the other hand, "_stext" seems always > available. So I think there are two ways to fix this, use "_stext" as this > version, or use "_text" and fix dso__load_sym to load "_text" as a function > symbol if exist. > I'm not sure why the "_text" is not loaded, is that a policy? Ah, I see. "_text" is not a function, just a label. That is why it is not found in function map. Hmm, in that case, maybe I should use a special case for checking reference symbol is a ref_reloc_sym and if so, use ref_reloc_sym->unrelocated_addr. Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- 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/