Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262139AbTEEW6U (ORCPT ); Mon, 5 May 2003 18:58:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262157AbTEEW6U (ORCPT ); Mon, 5 May 2003 18:58:20 -0400 Received: from a169212.upc-a.chello.nl ([62.163.169.212]:1284 "EHLO walton.kettenis.dyndns.org") by vger.kernel.org with ESMTP id S262139AbTEEW6T (ORCPT ); Mon, 5 May 2003 18:58:19 -0400 To: Richard Henderson Cc: David.Mosberger@acm.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] fix vsyscall unwind information References: <20030502004014$08e2@gated-at.bofh.it> <20030503210015$292c@gated-at.bofh.it> <20030504063010$279f@gated-at.bofh.it> <20030505074248.GA7812@twiddle.net> <16054.32214.804891.702812@panda.mostang.com> <20030505163444.GB9342@twiddle.net> From: Mark Kettenis Date: 06 May 2003 01:10:37 +0200 In-Reply-To: Richard Henderson's message of "Mon, 5 May 2003 09:34:44 -0700" Message-ID: <86d6ixdm6q.fsf@elgar.kettenis.dyndns.org> X-Mailer: Gnus v5.7/Emacs 20.7 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1346 Lines: 26 Richard Henderson writes: > On Mon, May 05, 2003 at 08:05:58AM -0700, David Mosberger-Tang wrote: > > Richard> Why? Certainly it isn't needed for x86. > > > > Certain applications (such as debuggers) want to know. Sure, you can > > do symbol matching (if you have the symbol table) or code-reading > > (assuming you know the exact sigreturn sequence), but having a marker > > would be more reliable and faster. > > Eh. The whole point was to *eliminate* the special cases. > > If the debugger does nothing special now, it'll see the symbol > from the VDSO in the backtrace and print __kernel_sigreturn. > Isn't this sufficient for the user to recognize what's going on? > Does it really need to print ? Unfortunately, GDB needs to be able to recognize signal trampolines in order to be able to single step correctly when a signal arrives. At least on some platforms. Could be that the code-path in question isn't used for Linux/i386, but I vaguely remember it does. Anyway, signal trampolines could be marked with a special augmentation in their CIE. Mark - 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/