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=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 983A8C55ABD for ; Sat, 14 Nov 2020 12:48:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 63FF722240 for ; Sat, 14 Nov 2020 12:48:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726789AbgKNMsB (ORCPT ); Sat, 14 Nov 2020 07:48:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:41174 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726112AbgKNMsB (ORCPT ); Sat, 14 Nov 2020 07:48:01 -0500 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 804B82222C; Sat, 14 Nov 2020 12:47:58 +0000 (UTC) Date: Sat, 14 Nov 2020 12:47:56 +0000 From: Catalin Marinas To: Andrey Konovalov Cc: Andrew Morton , Will Deacon , Vincenzo Frascino , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH mm v10 28/42] arm64: kasan: Allow enabling in-kernel MTE Message-ID: <20201114124755.GD2837@gaia> References: <123c654a82018611d38af8c83d1e90c16558ce52.1605305705.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <123c654a82018611d38af8c83d1e90c16558ce52.1605305705.git.andreyknvl@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 13, 2020 at 11:15:56PM +0100, Andrey Konovalov wrote: > From: Vincenzo Frascino > > Hardware tag-based KASAN relies on Memory Tagging Extension (MTE) > feature and requires it to be enabled. MTE supports > > This patch adds a new mte_enable_kernel() helper, that enables MTE in > Synchronous mode in EL1 and is intended to be called from KASAN runtime > during initialization. > > The Tag Checking operation causes a synchronous data abort as > a consequence of a tag check fault when MTE is configured in > synchronous mode. > > As part of this change enable match-all tag for EL1 to allow the > kernel to access user pages without faulting. This is required because > the kernel does not have knowledge of the tags set by the user in a > page. > > Note: For MTE, the TCF bit field in SCTLR_EL1 affects only EL1 in a > similar way as TCF0 affects EL0. > > MTE that is built on top of the Top Byte Ignore (TBI) feature hence we > enable it as part of this patch as well. > > Signed-off-by: Vincenzo Frascino > Co-developed-by: Andrey Konovalov > Signed-off-by: Andrey Konovalov Reviewed-by: Catalin Marinas