Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751225AbWIWPuM (ORCPT ); Sat, 23 Sep 2006 11:50:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751259AbWIWPuM (ORCPT ); Sat, 23 Sep 2006 11:50:12 -0400 Received: from tomts43-srv.bellnexxia.net ([209.226.175.110]:27272 "EHLO tomts43-srv.bellnexxia.net") by vger.kernel.org with ESMTP id S1751225AbWIWPuK (ORCPT ); Sat, 23 Sep 2006 11:50:10 -0400 Date: Sat, 23 Sep 2006 11:50:06 -0400 From: Mathieu Desnoyers To: Ingo Molnar Cc: Theodore Tso , Nicholas Miell , Paul Mundt , linux-kernel , Ingo Molnar , Jes Sorensen , Andrew Morton , Tom Zanussi , Richard J Moore , "Frank Ch. Eigler" , Michel Dagenais , Christoph Hellwig , Greg Kroah-Hartman , Thomas Gleixner , William Cohen , "Martin J. Bligh" Subject: Re: LTTng and SystemTAP (Everyone who is scared to read this huge thread, skip to here) Message-ID: <20060923155006.GA27012@Krystal> References: <20060917230623.GD8791@elte.hu> <450DEEA5.7080808@opersys.com> <20060918005624.GA30835@elte.hu> <450DFFC8.5080005@opersys.com> <20060918033027.GB11894@elte.hu> <20060918035216.GF9049@thunk.org> <450E1F6F.7040401@opersys.com> <20060918043248.GB19843@elte.hu> <20060918050310.GC15930@Krystal> <20060918151059.GA10106@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20060918151059.GA10106@elte.hu> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.4.32-grsec (i686) X-Uptime: 11:47:30 up 31 days, 12:56, 3 users, load average: 0.89, 0.51, 0.29 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: 1545 Lines: 38 * Ingo Molnar (mingo@elte.hu) wrote: > > * Mathieu Desnoyers wrote: > > > > Some of the extensive hooking you do in LTT could be aleviated to a > > > great degree if you used dynamic probes. For example the syscall > > > entry hackery in LTT looks truly scary. > > > > Yes, agreed. The last time I checked, I thought about moving this > > tracing code to the syscall_trace_entry/exit (used for security hooks > > and ptrace if I remember well). I just didn't have the time to do it > > yet. > > correct, that's where all such things (auditing, seccomp, ptrace, > sigstop, freezing, etc.) hook into. Much (all?) of the current entry.S > hacks can go away in favor of a much easier .c patch to > do_syscall_trace() and this would reduce a significantion portion of the > present intrusiveness of LTTng. > Hi Ingo, The only problem with do_syscall_trace is that it is only called at the beginning of the system call. LTT also needs a marker at the end of the system call to know when the control went back to user space. Any idea of a nice location (in C code preferably) for such a marker ? 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/