From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEA30C433E0 for ; Wed, 8 Jul 2020 07:39:03 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BD04620656 for ; Wed, 8 Jul 2020 07:39:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="wgrAKIne"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="uPQtrGDN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BD04620656 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=B/CbGUHEclmPa1Zp10y3JvXc1DV5O7k5S+lX6wT7Z/w=; b=wgrAKIneaMLEr2NFeRdMt5Nop TInoCum1dkFDkI3/dyKA4id1qMGgXJsMS0k0ehbxkufZlsaV8IQAF9/9KCJivfyrf7cP9A0ugSTip 2sZ9vztDGE/Bp4vxjWD6ZnwayCkOtConk89AhxLCnzm2Ue+RGgmaIp+GDZgjclbKxjvvl1jBtfoZB W0w9fxbjhWDd0WaQlJv+hXihK3mRM+B0qApRYuVgMIUcpdOEdaj9jGuLZzezH+n1edAyLCSY/LQCR UhtQLLmaP8Q87e77Jz6LpwJ9wX2c277CUbJIED6F8jkT7q/sq9LdVOPdUw0k9UH/BVzBFGMS2tIf9 5B0NNc7TA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jt4d2-0008MY-Ec; Wed, 08 Jul 2020 07:36:28 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jt4d1-0008M8-52 for linux-arm-kernel@lists.infradead.org; Wed, 08 Jul 2020 07:36:27 +0000 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EA4A720656; Wed, 8 Jul 2020 07:36:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594193785; bh=YLEgYj53wYk32PrzlV+lyPNbCQ9oHulDz021ZeDZ1dI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uPQtrGDNmKMy9iuc3Z24/enef6AqVUg7dXPeZIH6YdKY0H3TydaxnAcV555QM0sex FuwpsgO4ehoLOK/y1jCkAU2iODlOVlHWBKabP4H8IkXagneE9gf9vzyJHi1hHri7hL HSW3ndHFzUDvn1XK2MlW7das9NAR5ePkE2Z4ll0I= Date: Wed, 8 Jul 2020 08:36:21 +0100 From: Will Deacon To: Steve Capper Subject: Re: [PATCH] arm64: Introduce sysctl to disable pointer authentication Message-ID: <20200708073621.GA25261@willie-the-truck> References: <20200707173232.5535-1-steve.capper@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200707173232.5535-1-steve.capper@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200708_033627_260962_3F4A58C7 X-CRM114-Status: GOOD ( 13.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, catalin.marinas@arm.com, jeremy.linton@arm.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jul 07, 2020 at 06:32:32PM +0100, Steve Capper wrote: > Pointer authentication is a mandatory feature in the Armv8.3 > architecture that provides protection against return oriented > programming attacks. (meaning that all Arm CPUs targetting at least > Armv8.3 will have this feature). > > Once CONFIG_ARM64_PTR_AUTH=y, any systems with the hardware support for > pointer authentication will automatically have it enabled by the kernel. > > There are, however, situations where end users may want to disable > pointer authentication. One could be tracking down/working around a bug > in userspace relating to pointer auth. Also, one may wish to quantify > the performance overhead of pointer auth by running a workload > with/without it. If you're debugging userspace, just recompile your userspace application without ptr auth, in the same way that you might recompile with -g. The performance argument sucks; this stuff needs to be fast otherwise it's pointless. If you really need that last bit of speed, try Gentoo ;) Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel