From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261646AbUKSWCw (ORCPT ); Fri, 19 Nov 2004 17:02:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261641AbUKSWBB (ORCPT ); Fri, 19 Nov 2004 17:01:01 -0500 Received: from fw.osdl.org ([65.172.181.6]:4259 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261604AbUKSVx7 (ORCPT ); Fri, 19 Nov 2004 16:53:59 -0500 Date: Fri, 19 Nov 2004 13:53:38 -0800 (PST) From: Linus Torvalds To: Daniel Jacobowitz cc: Eric Pouech , Roland McGrath , Mike Hearn , linux-kernel@vger.kernel.org, Andrew Morton , wine-devel Subject: Re: ptrace single-stepping change breaks Wine In-Reply-To: <20041119212327.GA8121@nevyn.them.org> Message-ID: References: <200411152253.iAFMr8JL030601@magilla.sf.frob.com> <419E42B3.8070901@wanadoo.fr> <419E4A76.8020909@wanadoo.fr> <419E5A88.1050701@wanadoo.fr> <20041119212327.GA8121@nevyn.them.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 19 Nov 2004, Daniel Jacobowitz wrote: > > I'm getting the feeling that the question of whether to step into > signal handlers is orthogonal to single-stepping; maybe it should be a > separate ptrace operation. I really don't see why. If a controlling process is asking for single-stepping, then it damn well should get it. It it doesn't want to single-step through a signal handler, then it could decide to just put a breakpoint on the return point (possibly by modifying the signal handler save area). It's not like single-stepping into the signal handler in any way removes any information (while _not_ single-stepping into it clearly does). With the patch I just posted (assuming it works for people), Wine should at least have the choice. The behaviour now should be: - if the app sets TF on its own, it will cause a SIGTRAP which it can catch. - if the debugger sets TF with SINGLESTEP, it will single-step into a signal handler. - it the app sets TF _and_ you ptrace it, you the ptracer will see the debug event and catch it. However, doing a "continue" at that point will remove the TF flag (and always has), the app will normally then never see the trap. You can do a "signal SIGTRAP" to actually force the trap handler to tun, but that one won't actually single-step (it's a "continue" in all other senses). It sounds like the third case is what wine wants. Linus