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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,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 C6C68C433E7 for ; Thu, 8 Oct 2020 18:21:41 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 20CC622203 for ; Thu, 8 Oct 2020 18:21:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 20CC622203 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 801E16B005C; Thu, 8 Oct 2020 14:21:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7B2E46B005D; Thu, 8 Oct 2020 14:21:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6A0D26B0062; Thu, 8 Oct 2020 14:21:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0075.hostedemail.com [216.40.44.75]) by kanga.kvack.org (Postfix) with ESMTP id 3A8176B005C for ; Thu, 8 Oct 2020 14:21:38 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id C235F180AD806 for ; Thu, 8 Oct 2020 18:21:37 +0000 (UTC) X-FDA: 77349576234.09.knife34_07048cc271da Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin09.hostedemail.com (Postfix) with ESMTP id A39E1180AD804 for ; Thu, 8 Oct 2020 18:21:37 +0000 (UTC) X-HE-Tag: knife34_07048cc271da X-Filterd-Recvd-Size: 3129 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Thu, 8 Oct 2020 18:21:36 +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 91CC4D6E; Thu, 8 Oct 2020 11:21:35 -0700 (PDT) Received: from [10.37.12.22] (unknown [10.37.12.22]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2D4F63F802; Thu, 8 Oct 2020 11:21:31 -0700 (PDT) Subject: Re: [PATCH v4 29/39] arm64: mte: Switch GCR_EL1 in kernel entry and exit To: Catalin Marinas , Andrey Konovalov Cc: Dmitry Vyukov , kasan-dev@googlegroups.com, Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Elena Petrova , Branislav Rankov , Kevin Brodsky , Will Deacon , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1f2681fdff1aa1096df949cb8634a9be6bf4acc4.1601593784.git.andreyknvl@google.com> <20201002140652.GG7034@gaia> From: Vincenzo Frascino Message-ID: <1b2327ee-5f30-e412-7359-32a7a38b4c8d@arm.com> Date: Thu, 8 Oct 2020 19:24:12 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201002140652.GG7034@gaia> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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: Hi Catalin, On 10/2/20 3:06 PM, Catalin Marinas wrote: > On Fri, Oct 02, 2020 at 01:10:30AM +0200, Andrey Konovalov wrote: >> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c >> index 7c67ac6f08df..d1847f29f59b 100644 >> --- a/arch/arm64/kernel/mte.c >> +++ b/arch/arm64/kernel/mte.c >> @@ -23,6 +23,8 @@ >> #include >> #include >> >> +u64 gcr_kernel_excl __ro_after_init; >> + >> static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) >> { >> pte_t old_pte = READ_ONCE(*ptep); >> @@ -120,6 +122,13 @@ void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag) >> return ptr; >> } >> >> +void mte_init_tags(u64 max_tag) >> +{ >> + u64 incl = GENMASK(max_tag & MTE_TAG_MAX, 0); > > Nitpick: it's not obvious that MTE_TAG_MAX is a mask, so better write > this as GENMASK(min(max_tag, MTE_TAG_MAX), 0). > The two things do not seem equivalent because the format of the tags in KASAN is 0xFF and in MTE is 0xF, hence if extract the minimum whatever is the tag passed by KASAN it will always be MTE_TAG_MAX. To make it cleaner I propose: GENMASK(FIELD_GET(MTE_TAG_MAX, max_tag), 0); > Otherwise it looks fine. > > Reviewed-by: Catalin Marinas > -- Regards, Vincenzo