From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 130966 invoked by alias); 5 Jul 2018 19:31:25 -0000 Mailing-List: contact gnu-gabi-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Post: List-Help: List-Subscribe: Sender: gnu-gabi-owner@sourceware.org Received: (qmail 130909 invoked by uid 89); 5 Jul 2018 19:31:24 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Checked: by ClamAV 0.99.4 on sourceware.org X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=worried, stronger, conforming X-Spam-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS autolearn=ham version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on sourceware.org X-Spam-Level: X-Spam-User: qpsmtpd, 3 recipients X-HELO: mx1.redhat.com Received: from mx3-rdu2.redhat.com (HELO mx1.redhat.com) (66.187.233.73) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 05 Jul 2018 19:31:23 +0000 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8F3F1400ADCC; Thu, 5 Jul 2018 19:31:21 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-116-201.ams2.redhat.com [10.36.116.201]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 706DD2026D74; Thu, 5 Jul 2018 19:31:20 +0000 (UTC) Subject: Re: Invalid program counters and unwinding To: Michael Matz , Jakub Jelinek Cc: Jeff Law , GCC , GNU C Library , Binutils , gnu-gabi@sourceware.org References: <6feeaf09-0bc2-238b-42df-2ff915f3581e@redhat.com> <2b47dbd9-f1a2-1bf0-06ca-fca40660fabf@redhat.com> <6c555c05-e6d7-f37a-577f-4e0559c36f76@redhat.com> <20180702155448.GW7166@tucnak> From: Florian Weimer Message-ID: Date: Mon, 01 Jan 2018 00:00:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Thu, 05 Jul 2018 19:31:21 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Thu, 05 Jul 2018 19:31:21 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'fweimer@redhat.com' RCPT:'' X-IsSubscribed: yes X-SW-Source: 2018-q3/txt/msg00004.txt.bz2 On 07/02/2018 06:14 PM, Michael Matz wrote: > There is no such language in the psABI, no (at least I haven't found > anything; you had me worried for a moment :) ). But there's stronger one: > all functions through which unwinding is expected must provide CFI. So, > yes, such code isn't strictly conforming. But there we are, there's much > code that isn't and we still have to sensibly deal with it (if we can). > IMHO making guesses is better than to stop unwinding. And IMHO guessing > that it's FP-using is better than guessing that it's leaf, especially if > the PC in question was the result of a prior unwinding step (making it > clear that it certainly was_not_ leaf). Well, the previous frame could have been a signal handler frame, but I see your point. Anyway, I've proposed a BoF for these topics for the next Cauldron. Thanks, Florian