From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22013 invoked by alias); 26 Jun 2017 10:13:20 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 21828 invoked by uid 89); 26 Jun 2017 10:13:19 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD autolearn=unavailable version=3.3.2 spammy=H*r:4.76, safest, UD:org.uk, H*r:sk:4.82_1- X-HELO: pandora.armlinux.org.uk Received: from pandora.armlinux.org.uk (HELO pandora.armlinux.org.uk) (78.32.30.218) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 26 Jun 2017 10:13:18 +0000 Received: from n2100.armlinux.org.uk ([fd8f:7570:feb6:1:214:fdff:fe10:4f86]:51621) by pandora.armlinux.org.uk with esmtpsa (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.82_1-5b7a7c0-XX) (envelope-from ) id 1dPR15-0002OR-Ka; Mon, 26 Jun 2017 11:13:11 +0100 Received: from linux by n2100.armlinux.org.uk with local (Exim 4.76) (envelope-from ) id 1dPR0z-00067G-ND; Mon, 26 Jun 2017 11:13:05 +0100 Date: Mon, 26 Jun 2017 10:13:00 -0000 From: Russell King - ARM Linux To: Dave Martin Cc: linux-arm-kernel@lists.infradead.org, Edmund Grimley-Evans , libc-alpha@sourceware.org, gdb@sourceware.org Subject: Re: [RFC PATCH 0/2] ARM: Fix unparseable signal frame with CONFIG_IWMMXT Message-ID: <20170626101304.GG4902@n2100.armlinux.org.uk> References: <1498059983-13438-1-git-send-email-Dave.Martin@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1498059983-13438-1-git-send-email-Dave.Martin@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-SW-Source: 2017-06/txt/msg00024.txt.bz2 On Wed, Jun 21, 2017 at 04:46:01PM +0100, Dave Martin wrote: > In kernels with CONFIG_IWMMXT=y running on non-iWMMXt hardware, the > signal frame can be left partially uninitialised in such a way > that userspace cannot parse uc_regspace[] safely. In particular, > this means that the VFP registers cannot be located reliably in the > signal frame when a multi_v7_defconfig kernel is run on the > majority of platforms. > > I don't know whether any userspace has implemented any sort of > workaround for this, but the ABI by itself is insufficient anyway. > > This series attempts to omit the spurious iWMMXt record when > appropriate. > > Not extensively tested, and the ABI impact is unknown for now. Hmm, I would actually suggest that we poke in a correct size for the missing iWMMXt record, and an invalid magic number as the "simple" solution for this - that doesn't make any layout changes to the data structures, and is probably the safest solution for backporting. Going forward, I think something along the lines of your proposal is okay. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.