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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 25C40C433DB for ; Fri, 15 Jan 2021 15:09:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF26E2054F for ; Fri, 15 Jan 2021 15:09:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732695AbhAOPJK (ORCPT ); Fri, 15 Jan 2021 10:09:10 -0500 Received: from foss.arm.com ([217.140.110.172]:42436 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730569AbhAOPJI (ORCPT ); Fri, 15 Jan 2021 10:09:08 -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 1D92BD6E; Fri, 15 Jan 2021 07:08:23 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.41.13]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 270B53F70D; Fri, 15 Jan 2021 07:08:18 -0800 (PST) Date: Fri, 15 Jan 2021 15:08:11 +0000 From: Mark Rutland To: Vincenzo Frascino 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 Subject: Re: [PATCH v3 1/4] kasan, arm64: Add KASAN light mode Message-ID: <20210115150811.GA44111@C02TD0UTHF1T.local> References: <20210115120043.50023-1-vincenzo.frascino@arm.com> <20210115120043.50023-2-vincenzo.frascino@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210115120043.50023-2-vincenzo.frascino@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > 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(); } Thanks, Mark.