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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 586F3ECE564 for ; Tue, 18 Sep 2018 17:15:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1272220877 for ; Tue, 18 Sep 2018 17:15:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1272220877 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730473AbeIRWtF (ORCPT ); Tue, 18 Sep 2018 18:49:05 -0400 Received: from foss.arm.com ([217.140.101.70]:48418 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729037AbeIRWtF (ORCPT ); Tue, 18 Sep 2018 18:49:05 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B877A7A9; Tue, 18 Sep 2018 10:15:32 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 897A13F703; Tue, 18 Sep 2018 10:15:32 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 758CA1AE1396; Tue, 18 Sep 2018 18:15:51 +0100 (BST) Date: Tue, 18 Sep 2018 18:15:51 +0100 From: Will Deacon To: Robert Richter Cc: Mian Yousaf Kaukab , marc.zyngier@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, cwu@amperecomputing.com Subject: Re: [PATCH RESEND 3/6] arm64: add sysfs vulnerability show for spectre v1 Message-ID: <20180918171550.GN16498@arm.com> References: <20180827143310.641-1-ykaukab@suse.de> <20180827143310.641-4-ykaukab@suse.de> <20180917172206.GA3795@rric.localdomain> <20180918083805.GB14404@arm.com> <20180918095226.GJ3795@rric.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180918095226.GJ3795@rric.localdomain> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 18, 2018 at 11:52:27AM +0200, Robert Richter wrote: > On 18.09.18 09:38:05, Will Deacon wrote: > > On Mon, Sep 17, 2018 at 07:22:07PM +0200, Robert Richter wrote: > > > On 27.08.18 16:33:07, Mian Yousaf Kaukab wrote: > > > > Hard-coded since patches are merged and there are no configuration > > > > options. > > > > > > Could you add a list of upstream patches to the description that are > > > required to solve this? This would be a strict definition for the > > > mitigation being enabled and makes it easier to check if backports are > > > affected or not. A build-time check would be ideal (e.g. checking for > > > certain macros). > > > > Hmm, I don't grok what you're proposing here. Why do we need a build-time > > check (and to check what?) > > My concern is, that for kernel backports (esp. distro kernels) there > could be various interpretations of what "Mitigation: __user pointer > sanitization" means. So a list of upstream patches that need to be > backported in addition to this patch as a requirement would be good to > agree on. That should be documented in the patch description. > > If these mitigations are available in a kernel backport, that could be > even checked at build time. E.g. we could have a sanity check if the > macro array_index_nospec() is defined. But such a check does not > replace a code review of a kernel backport. > > I hope that makes sense? Ok, I see what you mean now, thanks. However, it doesn't sound much different than backporting a patch with dependencies, so I'd rather avoid adding additional code to treat this case specially. Will