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=-10.3 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=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 5BEC0C433E0 for ; Sat, 16 Jan 2021 17:58:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 21D862245C for ; Sat, 16 Jan 2021 17:58:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727522AbhAPR6R (ORCPT ); Sat, 16 Jan 2021 12:58:17 -0500 Received: from foss.arm.com ([217.140.110.172]:55552 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725964AbhAPR6Q (ORCPT ); Sat, 16 Jan 2021 12:58:16 -0500 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 D3540101E; Sat, 16 Jan 2021 05:43:22 -0800 (PST) Received: from [10.37.8.30] (unknown [10.37.8.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 61EBC3F719; Sat, 16 Jan 2021 05:43:20 -0800 (PST) Subject: Re: [PATCH v3 1/4] kasan, arm64: Add KASAN light mode To: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Marco Elver , Catalin Marinas , Branislav Rankov , Alexander Potapenko , Evgenii Stepanov , Andrey Konovalov , Andrey Ryabinin , Will Deacon , Dmitry Vyukov References: <20210115120043.50023-1-vincenzo.frascino@arm.com> <20210115120043.50023-2-vincenzo.frascino@arm.com> <20210115150811.GA44111@C02TD0UTHF1T.local> From: Vincenzo Frascino Message-ID: Date: Sat, 16 Jan 2021 13:47:08 +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: <20210115150811.GA44111@C02TD0UTHF1T.local> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mark, On 1/15/21 3:08 PM, Mark Rutland wrote: > On Fri, Jan 15, 2021 at 12:00:40PM +0000, Vincenzo Frascino wrote: >> Architectures supported by KASAN HW can provide a light mode of >> execution. On an MTE enabled arm64 hw for example this can be identified >> with the asynch mode of execution. >> In this mode, if a tag check fault occurs, the TFSR_EL1 register is >> updated asynchronously. The kernel checks the corresponding bits >> periodically. > > What's the expected usage of this relative to prod, given that this has > to be chosen at boot time? When/where is this expected to be used > relative to prod mode? > IIUC the light mode is meant for low spec devices. I let Andrey comment a bit more on this topic. >> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h >> index 18fce223b67b..3a7c5beb7096 100644 >> --- a/arch/arm64/include/asm/memory.h >> +++ b/arch/arm64/include/asm/memory.h >> @@ -231,7 +231,7 @@ static inline const void *__tag_set(const void *addr, u8 tag) >> } >> >> #ifdef CONFIG_KASAN_HW_TAGS >> -#define arch_enable_tagging() mte_enable_kernel() >> +#define arch_enable_tagging(mode) mte_enable_kernel(mode) > > Rather than passing a mode in, I think it'd be better to have: > > * arch_enable_tagging_prod() > * arch_enable_tagging_light() > > ... that we can map in the arch code to separate: > > * mte_enable_kernel_sync() > * mte_enable_kernel_async() > > ... as by construction that avoids calls with an unhandled mode, and we > wouldn't need the mode enum kasan_hw_tags_mode... > >> +static inline int hw_init_mode(enum kasan_arg_mode mode) >> +{ >> + switch (mode) { >> + case KASAN_ARG_MODE_LIGHT: >> + return KASAN_HW_TAGS_ASYNC; >> + default: >> + return KASAN_HW_TAGS_SYNC; >> + } >> +} > > ... and we can just have a wrapper like this to call either of the two functions directly, i.e. > > static inline void hw_enable_tagging_mode(enum kasan_arg_mode mode) > { > if (mode == KASAN_ARG_MODE_LIGHT) > arch_enable_tagging_mode_light(); > else > arch_enable_tagging_mode_prod(); > } > Fine by me, this would remove the need of adding a new enumeration as well and reflect on the arch code. I would keep "arch_enable_tagging_mode_sync" and "arch_enable_tagging_mode_async" though to give a clear indication in the KASAN code of the mode we are setting. I will adapt my code accordingly for v4. > Thanks, > Mark. > -- Regards, Vincenzo 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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 14F0CC433DB for ; Sat, 16 Jan 2021 13:45:09 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BB17923106 for ; Sat, 16 Jan 2021 13:45:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BB17923106 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=c9rQK+iStaTHBJFs7KGshroi4RE//s19KdwF0YvY1fQ=; b=rRYvq03o5ua196WbqpgHBaoXm 8rkRhF810CXB8Or+l5axuArpU6JZjDBfV+9kYzfDkM+RcsdF3X3+y1O3nGWhCgXG7MXYgIhsmmrLE YmbnHTglY6K2xeJXSe7AUrN23QX5roH5hgHm6KvFrAV4IY26Sx1HNqKk1v13NpLsWdeMlN5kqPx2u cxc97Y84eOCVUCXZY6DpK+U42N0NyhOykfXrgIWXU9YOHXCnivcvgDMFdlIUlpsSBJnUWRGyag8vt mTax6qP/eVfNCjpmGFKwH+/RUk2AKjdHTmMjFIJojXiXFpzI51GCl+c+Ljl+CNN+1iFBA7NC94mR7 ifuE0BJSw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l0lrT-0000qc-RK; Sat, 16 Jan 2021 13:43:27 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l0lrR-0000qF-1f for linux-arm-kernel@lists.infradead.org; Sat, 16 Jan 2021 13:43:25 +0000 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 D3540101E; Sat, 16 Jan 2021 05:43:22 -0800 (PST) Received: from [10.37.8.30] (unknown [10.37.8.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 61EBC3F719; Sat, 16 Jan 2021 05:43:20 -0800 (PST) Subject: Re: [PATCH v3 1/4] kasan, arm64: Add KASAN light mode To: Mark Rutland References: <20210115120043.50023-1-vincenzo.frascino@arm.com> <20210115120043.50023-2-vincenzo.frascino@arm.com> <20210115150811.GA44111@C02TD0UTHF1T.local> From: Vincenzo Frascino Message-ID: Date: Sat, 16 Jan 2021 13:47:08 +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: <20210115150811.GA44111@C02TD0UTHF1T.local> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210116_084325_165080_733129E5 X-CRM114-Status: GOOD ( 21.84 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marco Elver , Catalin Marinas , Branislav Rankov , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, Alexander Potapenko , Evgenii Stepanov , Andrey Konovalov , Dmitry Vyukov , Andrey Ryabinin , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Mark, On 1/15/21 3:08 PM, Mark Rutland wrote: > On Fri, Jan 15, 2021 at 12:00:40PM +0000, Vincenzo Frascino wrote: >> Architectures supported by KASAN HW can provide a light mode of >> execution. On an MTE enabled arm64 hw for example this can be identified >> with the asynch mode of execution. >> In this mode, if a tag check fault occurs, the TFSR_EL1 register is >> updated asynchronously. The kernel checks the corresponding bits >> periodically. > > What's the expected usage of this relative to prod, given that this has > to be chosen at boot time? When/where is this expected to be used > relative to prod mode? > IIUC the light mode is meant for low spec devices. I let Andrey comment a bit more on this topic. >> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h >> index 18fce223b67b..3a7c5beb7096 100644 >> --- a/arch/arm64/include/asm/memory.h >> +++ b/arch/arm64/include/asm/memory.h >> @@ -231,7 +231,7 @@ static inline const void *__tag_set(const void *addr, u8 tag) >> } >> >> #ifdef CONFIG_KASAN_HW_TAGS >> -#define arch_enable_tagging() mte_enable_kernel() >> +#define arch_enable_tagging(mode) mte_enable_kernel(mode) > > Rather than passing a mode in, I think it'd be better to have: > > * arch_enable_tagging_prod() > * arch_enable_tagging_light() > > ... that we can map in the arch code to separate: > > * mte_enable_kernel_sync() > * mte_enable_kernel_async() > > ... as by construction that avoids calls with an unhandled mode, and we > wouldn't need the mode enum kasan_hw_tags_mode... > >> +static inline int hw_init_mode(enum kasan_arg_mode mode) >> +{ >> + switch (mode) { >> + case KASAN_ARG_MODE_LIGHT: >> + return KASAN_HW_TAGS_ASYNC; >> + default: >> + return KASAN_HW_TAGS_SYNC; >> + } >> +} > > ... and we can just have a wrapper like this to call either of the two functions directly, i.e. > > static inline void hw_enable_tagging_mode(enum kasan_arg_mode mode) > { > if (mode == KASAN_ARG_MODE_LIGHT) > arch_enable_tagging_mode_light(); > else > arch_enable_tagging_mode_prod(); > } > Fine by me, this would remove the need of adding a new enumeration as well and reflect on the arch code. I would keep "arch_enable_tagging_mode_sync" and "arch_enable_tagging_mode_async" though to give a clear indication in the KASAN code of the mode we are setting. I will adapt my code accordingly for v4. > Thanks, > Mark. > -- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel