From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25990 invoked by alias); 13 May 2016 09:54:08 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 25889 invoked by uid 89); 13 May 2016 09:54:07 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.3 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=violates X-HELO: mx1.redhat.com Subject: Re: [PATCH 14/17 v5] Avoid stack-protecting signal-handling functions sibcalled from assembly. To: Nix References: <1457882222-22599-1-git-send-email-nix@esperi.org.uk> <1457882222-22599-15-git-send-email-nix@esperi.org.uk> Cc: libc-alpha@sourceware.org From: Florian Weimer Message-ID: <3a1025f2-8b0e-5d9b-01c4-7b4e4ef62cc8@redhat.com> Date: Fri, 13 May 2016 09:54:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.0 MIME-Version: 1.0 In-Reply-To: <1457882222-22599-15-git-send-email-nix@esperi.org.uk> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2016-05/txt/msg00270.txt.bz2 On 03/13/2016 04:16 PM, Nix wrote: > Certain signal-handling functions are sibcalled from assembly on > x86, both on Linux and the Hurd. As such, they depend on having > the same-shaped stack frame, an assumption it seems likely that > -fstack-protector violates. I think that's not actually true for tail calls to stack-protector-enabled functions from those who are not so enabled. The lack of rebuild is more problematic. Does it really make a difference, considering that the affected function is not active while we initialize the stack guard value? Thanks, Florian