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=-5.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 E44A8C5519F for ; Thu, 12 Nov 2020 18:53:58 +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 7704D2222F for ; Thu, 12 Nov 2020 18:53:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="2/AldCyN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7704D2222F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com 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=3F/i6bkxU1dBg0BlY3CJAB3VvmNiEW97CJRxECys+K4=; b=2/AldCyNsvTFfThN2Lr49oaza dhBFTZBHxf8cNBnUZV5Tkxr0uy6Chvrc5LUC4cTOQzaO4UF+GpeFyYTQpYmB4DvcJcRLEMwqnZjj2 Ek5gpbALtlG0B0a+CAZ3kgjjt1djCVEw5If77Soe8SSyuAqLemSOrvxtJGHbTQHr6nXKV6XwAU56d v+PgOkUgX2oc6ggYKeS5Ghk68wb63oGlaGr3i2982FO8uxhuBiXgVXR4AnQxAgjzNBN4IAYcHvoow /3ktr0GbaxEA+WaULhtQ/Ua3iWhQS2tqDkwVMRqFX8Ld8MqpwR/YsvkJ0lAnhB+VkTiRZcZ05Zxo9 8jnRpHq8w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kdHiw-0002kl-NQ; Thu, 12 Nov 2020 18:53:34 +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 1kdHit-0002jj-Iz for linux-arm-kernel@lists.infradead.org; Thu, 12 Nov 2020 18:53:32 +0000 Received: from gaia (unknown [2.26.170.190]) (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 1009722228; Thu, 12 Nov 2020 18:53:27 +0000 (UTC) Date: Thu, 12 Nov 2020 18:53:25 +0000 From: Catalin Marinas To: "Eric W. Biederman" Subject: Re: [PATCH v14 8/8] arm64: expose FAR_EL1 tag bits in siginfo Message-ID: <20201112185324.GP29613@gaia> References: <0ce3d90b5d6a4457b2fe3b0582f61fab70b17dfc.1604523707.git.pcc@google.com> <87eel2ypy3.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87eel2ypy3.fsf@x220.int.ebiederm.org> 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-20201112_135331_700984_97EDD819 X-CRM114-Status: GOOD ( 20.29 ) 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: Peter Collingbourne , Helge Deller , Kevin Brodsky , Oleg Nesterov , linux-api@vger.kernel.org, "James E.J. Bottomley" , Kostya Serebryany , Linux ARM , Andrey Konovalov , David Spickett , Vincenzo Frascino , Will Deacon , Dave Martin , Evgenii Stepanov , Richard Henderson 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 Mon, Nov 09, 2020 at 07:13:08PM -0600, Eric W. Biederman wrote: > Peter Collingbourne writes: > > The kernel currently clears the tag bits (i.e. bits 56-63) in the fault > > address exposed via siginfo.si_addr and sigcontext.fault_address. However, > > the tag bits may be needed by tools in order to accurately diagnose > > memory errors, such as HWASan [1] or future tools based on the Memory > > Tagging Extension (MTE). > > > > We should not stop clearing these bits in the existing fault address > > fields, because there may be existing userspace applications that are > > expecting the tag bits to be cleared. Instead, create a new pair of > > fields in siginfo._sigfault, and store the tag bits of FAR_EL1 there, > > together with a mask specifying which bits are valid. > > > > A flag is added to si_faultflags to allow userspace to determine whether > > the values in the fields are valid. [...] > What prevents adding a sigaction sa_flag SA_EXPOSE_TABITS that when set > causes the high bits to be set, and when clear (the default) will have > the signal delivery code clear those bits. Thanks for the review so far Eric. If the SA_EXPOSE_TAGBITS idea works, I'd much rather have that than the ultra generic xflags approach. Given that Peter is going to rework this part, could you please pick the first clean-up patches via your tree? If there are dependencies with the reworked arm64 patches, I'm also happy for them to go via your tree. Thanks. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel