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=-8.3 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=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 9AF48C56201 for ; Thu, 12 Nov 2020 09:52:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1530322228 for ; Thu, 12 Nov 2020 09:52:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1530322228 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 8CAE36B005D; Thu, 12 Nov 2020 04:52:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 855326B0068; Thu, 12 Nov 2020 04:52:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6F5C96B006C; Thu, 12 Nov 2020 04:52:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0127.hostedemail.com [216.40.44.127]) by kanga.kvack.org (Postfix) with ESMTP id 3E38E6B005D for ; Thu, 12 Nov 2020 04:52:06 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id E1BE88249980 for ; Thu, 12 Nov 2020 09:52:05 +0000 (UTC) X-FDA: 77475300210.24.walk50_300a1c427305 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id BF41C1A4A5 for ; Thu, 12 Nov 2020 09:52:05 +0000 (UTC) X-HE-Tag: walk50_300a1c427305 X-Filterd-Recvd-Size: 3783 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Thu, 12 Nov 2020 09:52:05 +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 54D9E139F; Thu, 12 Nov 2020 01:52:04 -0800 (PST) Received: from [10.37.12.33] (unknown [10.37.12.33]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 47B643F73C; Thu, 12 Nov 2020 01:52:01 -0800 (PST) Subject: Re: [PATCH v9 32/44] arm64: mte: Switch GCR_EL1 in kernel entry and exit To: Catalin Marinas Cc: Andrey Konovalov , Will Deacon , 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 References: <25401c15dc19c7b672771f5b49a208d6e77bfeb5.1605046192.git.andreyknvl@google.com> <20201112093908.GE29613@gaia> <20201112094553.GG29613@gaia> From: Vincenzo Frascino Message-ID: <6aec6a77-f9b0-cf73-6bf3-4f8df8f8cd13@arm.com> Date: Thu, 12 Nov 2020 09:55:05 +0000 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: <20201112094553.GG29613@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: On 11/12/20 9:45 AM, Catalin Marinas wrote: > On Thu, Nov 12, 2020 at 09:45:45AM +0000, Vincenzo Frascino wrote: >> On 11/12/20 9:39 AM, Catalin Marinas wrote: >>> On Tue, Nov 10, 2020 at 11:10:29PM +0100, Andrey Konovalov wrote: >>>> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c >>>> index 664c968dc43c..dbda6598c19d 100644 >>>> --- a/arch/arm64/kernel/mte.c >>>> +++ b/arch/arm64/kernel/mte.c >>>> @@ -129,6 +131,26 @@ void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag) >>>> return ptr; >>>> } >>>> >>>> +void mte_init_tags(u64 max_tag) >>>> +{ >>>> + static bool gcr_kernel_excl_initialized = false; >>>> + >>>> + if (!gcr_kernel_excl_initialized) { >>>> + /* >>>> + * The format of the tags in KASAN is 0xFF and in MTE is 0xF. >>>> + * This conversion extracts an MTE tag from a KASAN tag. >>>> + */ >>>> + u64 incl = GENMASK(FIELD_GET(MTE_TAG_MASK >> MTE_TAG_SHIFT, >>>> + max_tag), 0); >>>> + >>>> + gcr_kernel_excl = ~incl & SYS_GCR_EL1_EXCL_MASK; >>>> + gcr_kernel_excl_initialized = true; >>>> + } >>>> + >>>> + /* Enable the kernel exclude mask for random tags generation. */ >>>> + write_sysreg_s(SYS_GCR_EL1_RRND | gcr_kernel_excl, SYS_GCR_EL1); >>>> +} >>> >>> I don't think this function belongs to this patch. There is an earlier >>> patch that talks about mte_init_tags() but no trace of it until this >>> patch. >> >> Could you please point out to which patch are you referring to? > > I replied to it already (or you can search ;)). But this patch is about > switching GCR_EL1 on exception entry/exit rather than setting up the > initial kernel GCR_EL1 value. > Temporally after I asked ;) (I give you the benefit of delay of the mail server ;) ). I think that during the development the logic changed a bit, but I agree that the comments are outdated. I am fine to move the code. -- Regards, Vincenzo