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=unavailable 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 597C2C55179 for ; Thu, 5 Nov 2020 17:42:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C13BC20709 for ; Thu, 5 Nov 2020 17:42:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C13BC20709 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 28F506B0170; Thu, 5 Nov 2020 12:42:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 23E886B0171; Thu, 5 Nov 2020 12:42:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0E07A6B0172; Thu, 5 Nov 2020 12:42:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0080.hostedemail.com [216.40.44.80]) by kanga.kvack.org (Postfix) with ESMTP id D25416B0170 for ; Thu, 5 Nov 2020 12:42:48 -0500 (EST) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 7A1F9181AC9C6 for ; Thu, 5 Nov 2020 17:42:48 +0000 (UTC) X-FDA: 77451084816.01.hair74_1c0daa9272cb Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin01.hostedemail.com (Postfix) with ESMTP id 3063110229464 for ; Thu, 5 Nov 2020 17:42:48 +0000 (UTC) X-HE-Tag: hair74_1c0daa9272cb X-Filterd-Recvd-Size: 2475 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf32.hostedemail.com (Postfix) with ESMTP for ; Thu, 5 Nov 2020 17:42:47 +0000 (UTC) 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 44E29206CA; Thu, 5 Nov 2020 17:42:42 +0000 (UTC) Date: Thu, 5 Nov 2020 17:42:39 +0000 From: Catalin Marinas To: Andrey Konovalov Cc: Will Deacon , Vincenzo Frascino , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , Andrew Morton , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 32/43] arm64: mte: Switch GCR_EL1 in kernel entry and exit Message-ID: <20201105174239.GI30030@gaia> References: <5d9ece04df8e9d60e347a2f6f96b8c52316bfe66.1604531793.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5d9ece04df8e9d60e347a2f6f96b8c52316bfe66.1604531793.git.andreyknvl@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000009, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Nov 05, 2020 at 12:18:47AM +0100, Andrey Konovalov wrote: > From: Vincenzo Frascino > > When MTE is present, the GCR_EL1 register contains the tags mask that > allows to exclude tags from the random generation via the IRG instruction. > > With the introduction of the new Tag-Based KASAN API that provides a > mechanism to reserve tags for special reasons, the MTE implementation > has to make sure that the GCR_EL1 setting for the kernel does not affect > the userspace processes and viceversa. > > Save and restore the kernel/user mask in GCR_EL1 in kernel entry and exit. > > Signed-off-by: Vincenzo Frascino > Co-developed-by: Andrey Konovalov > Signed-off-by: Andrey Konovalov Reviewed-by: Catalin Marinas