From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12841 invoked by alias); 22 Sep 2006 15:38:06 -0000 Received: (qmail 12834 invoked by uid 22791); 22 Sep 2006 15:38:06 -0000 X-Spam-Status: No, hits=-2.4 required=5.0 tests=AWL,BAYES_00,FORGED_RCVD_HELO X-Spam-Check-By: sourceware.org Received: from tomts22.bellnexxia.net (HELO tomts22-srv.bellnexxia.net) (209.226.175.184) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 22 Sep 2006 15:38:00 +0000 Received: from krystal.dyndns.org ([67.68.212.231]) by tomts22-srv.bellnexxia.net (InterMail vM.5.01.06.13 201-253-122-130-113-20050324) with ESMTP id <20060922153758.VHNW10262.tomts22-srv.bellnexxia.net@krystal.dyndns.org> for ; Fri, 22 Sep 2006 11:37:58 -0400 Received: from localhost (localhost [127.0.0.1]) (uid 1000) by krystal.dyndns.org with local; Fri, 22 Sep 2006 11:27:37 -0400 id 001C248C.451400E9.000033E5 Date: Fri, 22 Sep 2006 15:38:00 -0000 From: Mathieu Desnoyers To: Jeremy Fitzhardinge Cc: Martin Bligh , "Frank Ch. Eigler" , Masami Hiramatsu , prasanna@in.ibm.com, Andrew Morton , Ingo Molnar , Paul Mundt , linux-kernel , Jes Sorensen , Tom Zanussi , Richard J Moore , Michel Dagenais , Christoph Hellwig , Greg Kroah-Hartman , Thomas Gleixner , William Cohen , ltt-dev@shafik.org, systemtap@sources.redhat.com, Alan Cox Subject: Re: [PATCH] Linux Kernel Markers 0.7 for 2.6.17 (with type checking!) Message-ID: <20060922152737.GA30668@Krystal> References: <20060921232024.GA16155@Krystal> <451331A1.3020601@goop.org> <20060922020119.GA28712@Krystal> <45134539.7070305@goop.org> <20060922021400.GA6330@Krystal> <45135FA0.1030403@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <45135FA0.1030403@goop.org> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.4.32-grsec (i686) X-Uptime: 11:22:15 up 30 days, 12:30, 5 users, load average: 0.19, 0.15, 0.15 User-Agent: Mutt/1.5.13 (2006-08-11) X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q3/txt/msg00705.txt.bz2 * Jeremy Fitzhardinge (jeremy@goop.org) wrote: > Mathieu Desnoyers wrote: > >* Jeremy Fitzhardinge (jeremy@goop.org) wrote: > > > >>Mathieu Desnoyers wrote: > >> > >>>#define MARK_SYM(name) \ > >>> do { \ > >>> __label__ here; \ > >>> volatile static void *__mark_kprobe_##name \ > >>> asm (MARK_CALL_PREFIX#name) \ > >>> __attribute__((unused)) = &&here; \ > >>>here: \ > >>> do { } while(0); \ > >>> } while(0) > >>> > >>>Which fixes the problem. Some tests showed me that the compiler does not > >>>unroll > >>>an otherwise unrolled loop when this specific macro is called. (test > >>>done with > >>>-funroll-all-loops). > >>> > >>Eh? I thought you wanted to avoid changing the generated code? > >>Inhibiting loop unrolling could be a pretty large change... > >> > >> > > > >Yes, if possible. But letting gcc duplicate those symbols brings many > >questions, > >such as : how can we name each of them differently ? Is there any way to > >automatically increment an "identifier" counter in assembly ? > > Use a section instead: > > struct marker { > const char *name; > const void *location; > }; > > #define MARKER_SYM(name) > do { > __label__ here; > here: asm volatile(".section \".markers\"; .long %0, %1; > .previous" : : "m" (#name), "m" (*&&here));\ > } while(0); > > Not a linker symbol, but it does let you find all the places containing > a particular mark. > Very clever idea, as it lessens the impact on the compiler optimisations. Any ideas about how we could fit in a list of "read" memory constraints based on a vargs list in the macro ? Mathieu OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj.gpg Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68