From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1986 invoked by alias); 5 Jul 2008 18:08:10 -0000 Received: (qmail 1978 invoked by uid 22791); 5 Jul 2008 18:08:09 -0000 X-Spam-Status: No, hits=-2.6 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from verein.lst.de (HELO verein.lst.de) (213.95.11.210) by sourceware.org (qpsmtpd/0.31) with ESMTP; Sat, 05 Jul 2008 18:07:52 +0000 Received: from verein.lst.de (localhost [127.0.0.1]) by verein.lst.de (8.12.3/8.12.3/Debian-7.1) with ESMTP id m65I6ZNW009237 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Sat, 5 Jul 2008 20:06:35 +0200 Received: (from hch@localhost) by verein.lst.de (8.12.3/8.12.3/Debian-6.6) id m65I6ZkC009235; Sat, 5 Jul 2008 20:06:35 +0200 Date: Sat, 05 Jul 2008 18:08:00 -0000 From: Christoph Hellwig To: James Bottomley Cc: Christoph Hellwig , Peter Zijlstra , ksummit-2008-discuss@lists.linux-foundation.org, Roland McGrath , systemtap@sources.redhat.com Subject: Re: [Ksummit-2008-discuss] DTrace Message-ID: <20080705180635.GA9074@lst.de> References: <20080630201031.GF7988@mit.edu> <20080630204219.GA6631@redhat.com> <20080701024140.GB28143@mit.edu> <20080701070746.C6DAD15420E@magilla.localdomain> <20080701101507.GB22717@mit.edu> <20080701200632.6790A1541F5@magilla.localdomain> <20080701231327.GA5829@mit.edu> <1215251049.6320.15.camel@lappy.programming.kicks-ass.net> <20080705100536.GA18534@lst.de> <1215265789.3439.8.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1215265789.3439.8.camel@localhost.localdomain> User-Agent: Mutt/1.3.28i X-Spam-Score: 0 () X-Scanned-By: MIMEDefang 2.39 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: 2008-q3/txt/msg00053.txt.bz2 On Sat, Jul 05, 2008 at 08:49:49AM -0500, James Bottomley wrote: > To be fair, you can simply "just write" entry (jprobes) and return > probes (kretprobes). For the entry probes, if you want access to the > function arguments you need to know the deep magic of the calling > conventions of your platform (pretty easy on x86, though). For jprobes your probe just has the same signature as the probed function, and for kretprobes you use the regs_return_value() arch-provided helper. It's really quite easy and covers 90% of what I need as a kernel developer. Well, except for the cases where gcc gets to smart and inlines enormous callchains, but at least in XFS we've just delcared everything noinline..