From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31846 invoked by alias); 1 Nov 2004 20:45:58 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 31837 invoked from network); 1 Nov 2004 20:45:56 -0000 Received: from unknown (HELO walton.sibelius.xs4all.nl) (82.92.89.47) by sourceware.org with SMTP; 1 Nov 2004 20:45:56 -0000 Received: from elgar.sibelius.xs4all.nl (elgar.sibelius.xs4all.nl [192.168.0.2]) by walton.sibelius.xs4all.nl (8.13.0/8.13.0) with ESMTP id iA1KjTwp011354; Mon, 1 Nov 2004 21:45:29 +0100 (CET) Received: from elgar.sibelius.xs4all.nl (localhost [127.0.0.1]) by elgar.sibelius.xs4all.nl (8.12.6p3/8.12.6) with ESMTP id iA1KjTKQ000422; Mon, 1 Nov 2004 21:45:29 +0100 (CET) (envelope-from kettenis@elgar.sibelius.xs4all.nl) Received: (from kettenis@localhost) by elgar.sibelius.xs4all.nl (8.12.6p3/8.12.6/Submit) id iA1KjKDg000415; Mon, 1 Nov 2004 21:45:20 +0100 (CET) Date: Mon, 01 Nov 2004 20:45:00 -0000 Message-Id: <200411012045.iA1KjKDg000415@elgar.sibelius.xs4all.nl> From: Mark Kettenis To: drow@false.org CC: gdb-patches@sources.redhat.com, ezannoni@redhat.com, cagney@gnu.org, roland@redhat.com In-reply-to: <20041101161552.GA26993@nevyn.them.org> (message from Daniel Jacobowitz on Mon, 1 Nov 2004 11:15:52 -0500) Subject: Re: [rfa] Attach vsyscall support for GNU/Linux References: <20041024185345.GB22700@nevyn.them.org> <200410242054.i9OKsjnl028328@elgar.sibelius.xs4all.nl> <20041024231636.GA21927@nevyn.them.org> <200410252212.i9PMCQhJ031724@elgar.sibelius.xs4all.nl> <20041101161552.GA26993@nevyn.them.org> X-SW-Source: 2004-11/txt/msg00024.txt.bz2 Date: Mon, 1 Nov 2004 11:15:52 -0500 From: Daniel Jacobowitz On Tue, Oct 26, 2004 at 12:12:26AM +0200, Mark Kettenis wrote: > Date: Sun, 24 Oct 2004 19:16:36 -0400 > From: Daniel Jacobowitz > > Thanks for the explanation Daniel! > > Unwinding bugs aside, I think it's valuable for GDB to know that it is > at a signal trampoline. I think the custom display in backtrace is > valuable. That means we should look for signal handlers before looking > for CFI. For NPTL that value judgement would fall the other way - not > having to special-case signal handlers is a clear win. > > Given the fact that it is desirable for GDB to know that it's dealing > with a signal handler, I think the correct approach is to extend the > DWARF2 unwinder with a method to get the frame type, similar to what > we already do for pre-initializing the register state. > > I'll see if I can come up with a patch for you to test. Had any time for this, Mark? If not, I can try it. I forgot about it :-(. I had a look just now, but unfortunately it's not as easy as I thought. The frame type is currently hard-coded in the unwinder. This is wrong, but Andrew thinks it's wrong in a different way than I. At least, that's what I think. I'll have to learn reading UML diagrams first. I'll throw some Feynman diagrams into my next mail to get even with him ;-). This is not going to be a simple fix, therefore... I think this patch is very important for 6.3. ...you might want to convince Andrew to include your origional patch in 6.3. Or better yet, a patch that prepends a signal frame unwinder only for Linux. If you succeed, you have my blessing to check this in on mainline too, provided you add a big fat warning why this is done and that it's so wrong. Sorry, Mark