Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932173AbWIVQTI (ORCPT ); Fri, 22 Sep 2006 12:19:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932295AbWIVQTI (ORCPT ); Fri, 22 Sep 2006 12:19:08 -0400 Received: from tomts16-srv.bellnexxia.net ([209.226.175.4]:49655 "EHLO tomts16-srv.bellnexxia.net") by vger.kernel.org with ESMTP id S932173AbWIVQTG (ORCPT ); Fri, 22 Sep 2006 12:19:06 -0400 Date: Fri, 22 Sep 2006 12:13:53 -0400 From: Mathieu Desnoyers To: Karim Yaghmour Cc: Ingo Molnar , Martin Bligh , "Frank Ch. Eigler" , Masami Hiramatsu , prasanna@in.ibm.com, Andrew Morton , 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 0.5 for Linux 2.6.17 (with probe management) Message-ID: <20060922161353.GA1569@Krystal> References: <20060921160009.GA30115@Krystal> <20060921160656.GA24774@elte.hu> <20060921214248.GA10097@Krystal> <20060922070714.GB4167@elte.hu> <20060922150810.GB20839@Krystal> <45140E33.9030509@opersys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <45140E33.9030509@opersys.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.4.32-grsec (i686) X-Uptime: 12:05:31 up 30 days, 13:14, 4 users, load average: 0.60, 0.44, 0.27 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1376 Lines: 37 * Karim Yaghmour (karim@opersys.com) wrote: > So if your proposal is to amend the markup to use the short-jmp+nops > at every marker site instead of my earlier suggestion for the bprobes > thing, I'm all with you. > First of all, I think that specific architecture-specific optimisations can and should be integrated in a more generic portable framework. Hrm, your comment makes me think of an interesting idea : .align jump_address: near jump to end setup_stack_address: setup stack call empty function end: So, instead of putting nops in the target area, we fill it with a useful function call. Near jump being 2 bytes, it might be much easier to modify. If necessary, making sure the instruction is aligned would help to change it atomically. If we mark the jump address, the setup stack address and the end tag address with symbols, we can easily calculate (portably) the offset of the near jump to activate either the setup_stack_address or end tags. Mathieu OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj.gpg Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - 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/