From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29007 invoked by alias); 16 Nov 2007 20:35:48 -0000 Received: (qmail 28998 invoked by uid 22791); 16 Nov 2007 20:35:48 -0000 X-Spam-Status: No, hits=-2.2 required=5.0 tests=AWL,BAYES_00,DK_POLICY_SIGNSOME,FORGED_RCVD_HELO,TW_EB X-Spam-Check-By: sourceware.org Received: from tomts10.bellnexxia.net (HELO tomts10-srv.bellnexxia.net) (209.226.175.54) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 16 Nov 2007 20:35:43 +0000 Received: from toip4.srvr.bell.ca ([209.226.175.87]) by tomts10-srv.bellnexxia.net (InterMail vM.5.01.06.13 201-253-122-130-113-20050324) with ESMTP id <20071116203541.IRKG1733.tomts10-srv.bellnexxia.net@toip4.srvr.bell.ca> for ; Fri, 16 Nov 2007 15:35:41 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Aq4HAP+NPUdMROHU/2dsb2JhbACBXw Received: from bas5-montreal19-1279582676.dsl.bell.ca (HELO krystal.dyndns.org) ([76.68.225.212]) by toip4.srvr.bell.ca with ESMTP; 16 Nov 2007 15:38:21 -0500 Received: from localhost (localhost [127.0.0.1]) (uid 1000) by krystal.dyndns.org with local; Fri, 16 Nov 2007 15:35:39 -0500 id 001CE3B0.473DFF1B.00007EEA Date: Fri, 16 Nov 2007 20:35:00 -0000 From: Mathieu Desnoyers To: "Frank Ch. Eigler" Cc: ltt-dev@shafik.org, Systemtap List Subject: Re: patches to actually use markers? Message-ID: <20071116203539.GA32261@Krystal> References: <472633E3.1050507@redhat.com> <20071029220454.GB4233@Krystal> <4728AD5F.1010604@redhat.com> <473DEBB7.40607@redhat.com> <20071116192415.GA25794@Krystal> <20071116201015.GA29545@Krystal> <20071116202645.GB25326@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20071116202645.GB25326@redhat.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 15:33:09 up 13 days, 1:38, 6 users, load average: 1.84, 1.68, 1.44 User-Agent: Mutt/1.5.16 (2007-06-11) X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2007-q4/txt/msg00358.txt.bz2 * Frank Ch. Eigler (fche@redhat.com) wrote: > Hi - > > On Fri, Nov 16, 2007 at 03:10:15PM -0500, Mathieu Desnoyers wrote: > > [...] > > > How would this syscall specific function get ebx or the string, > > > without ebx (or regs) being passed as marker arguments? > > > That's the idea : in the syscall specific function (not in > > syscall_trace()), we add another marker that takes the syscall > > specific arguments as parameter. I think we use the same approach > > there. > > I see. Yes, per-systemcall markers would be welcome by our group, and > ones not dependent on TIF_TRACE or whatnot even more so. But were > trying not to get too optimistic. > I use per-systemcall markers for the principally useful systemcalls, but I also instrument syscall_trace() to get all the other syscalls (new ones, etc..). I add my own TIF_KERNEL_TRACE, which is a thread flag enabled in each and every thread when tracing is active. I think both have their own advantage (complete information vs instrumentation of every, even less important, system calls). > > > What I was saying is that we can't extract the string from > > syscall_trace() because we have no idea it is a string. > > If "we" is a marker callback function that is given the system call > number, it can be taught. This is the sort of thing we do currently > in systemtap script code based upon kprobes. > Yeah.. but I fear that within the kernel it can become quickly very ugly. Mathieu > - FChE -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68