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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 1045DC433E0 for ; Fri, 15 May 2020 17:17:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CE56A206D8 for ; Fri, 15 May 2020 17:17:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE56A206D8 Authentication-Results: mail.kernel.org; dmarc=none (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 574878E001D; Fri, 15 May 2020 13:17:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 524698E0001; Fri, 15 May 2020 13:17:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 39F8A8E001D; Fri, 15 May 2020 13:17:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0206.hostedemail.com [216.40.44.206]) by kanga.kvack.org (Postfix) with ESMTP id 01F0B8E0001 for ; Fri, 15 May 2020 13:17:10 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id A7CCD6D894 for ; Fri, 15 May 2020 17:17:10 +0000 (UTC) X-FDA: 76819609020.10.vest72_46d7b205a743 X-HE-Tag: vest72_46d7b205a743 X-Filterd-Recvd-Size: 3364 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf25.hostedemail.com (Postfix) with ESMTP for ; Fri, 15 May 2020 17:17:10 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CC414113E; Fri, 15 May 2020 10:17:09 -0700 (PDT) Received: from localhost.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 339633F305; Fri, 15 May 2020 10:17:08 -0700 (PDT) From: Catalin Marinas To: linux-arm-kernel@lists.infradead.org Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org, Will Deacon , Dave P Martin , Vincenzo Frascino , Szabolcs Nagy , Kevin Brodsky , Andrey Konovalov , Peter Collingbourne Subject: [PATCH v4 24/26] arm64: mte: Introduce early param to disable MTE support Date: Fri, 15 May 2020 18:16:10 +0100 Message-Id: <20200515171612.1020-25-catalin.marinas@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200515171612.1020-1-catalin.marinas@arm.com> References: <20200515171612.1020-1-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: For performance analysis it may be desirable to disable MTE altogether via an early param. Introduce arm64.mte_disable and, if true, filter out the sanitised ID_AA64PFR1_EL1.MTE field to avoid exposing the HWCAP to user. Signed-off-by: Catalin Marinas Cc: Will Deacon --- Notes: New in v4. Documentation/admin-guide/kernel-parameters.txt | 4 ++++ arch/arm64/kernel/cpufeature.c | 11 +++++++++++ 2 files changed, 15 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentat= ion/admin-guide/kernel-parameters.txt index f2a93c8679e8..7436e7462b85 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -373,6 +373,10 @@ arcrimi=3D [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards Format: ,, =20 + arm64.mte_disable=3D + [ARM64] Disable Linux support for the Memory + Tagging Extension (both user and in-kernel). + ataflop=3D [HW,M68k] =20 atarimouse=3D [HW,MOUSE] Atari Mouse diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeatur= e.c index aaadc1cbc006..f7596830694f 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -126,12 +126,23 @@ static void cpu_enable_cnp(struct arm64_cpu_capabil= ities const *cap); static bool __system_matches_cap(unsigned int n); =20 #ifdef CONFIG_ARM64_MTE +static bool mte_disable; + +static int __init arm64_mte_disable(char *buf) +{ + return strtobool(buf, &mte_disable); +} +early_param("arm64.mte_disable", arm64_mte_disable); + s64 mte_ftr_filter(const struct arm64_ftr_bits *ftrp, s64 val) { struct device_node *np; static bool memory_checked =3D false; static bool mte_capable =3D true; =20 + if (mte_disable) + return ID_AA64PFR1_MTE_NI; + /* EL0-only MTE is not supported by Linux, don't expose it */ if (val < ID_AA64PFR1_MTE) return ID_AA64PFR1_MTE_NI;