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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,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 AD904C433E0 for ; Mon, 22 Feb 2021 11:11:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4D36464E4B for ; Mon, 22 Feb 2021 11:11:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230316AbhBVLLU (ORCPT ); Mon, 22 Feb 2021 06:11:20 -0500 Received: from foss.arm.com ([217.140.110.172]:41454 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230171AbhBVLLQ (ORCPT ); Mon, 22 Feb 2021 06:11:16 -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 1CF701FB; Mon, 22 Feb 2021 03:10:30 -0800 (PST) Received: from [10.37.8.9] (unknown [10.37.8.9]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id ADCBB3F73B; Mon, 22 Feb 2021 03:10:26 -0800 (PST) Subject: Re: [PATCH v13 1/7] arm64: mte: Add asynchronous mode support To: Andrey Konovalov Cc: Linux ARM , LKML , kasan-dev , Andrew Morton , Catalin Marinas , Will Deacon , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Lorenzo Pieralisi References: <20210211153353.29094-1-vincenzo.frascino@arm.com> <20210211153353.29094-2-vincenzo.frascino@arm.com> From: Vincenzo Frascino Message-ID: Date: Mon, 22 Feb 2021 11:14:38 +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: 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 On 2/12/21 9:21 PM, Andrey Konovalov wrote: > On Thu, Feb 11, 2021 at 4:34 PM Vincenzo Frascino > wrote: >> >> MTE provides an asynchronous mode for detecting tag exceptions. In >> particular instead of triggering a fault the arm64 core updates a >> register which is checked by the kernel after the asynchronous tag >> check fault has occurred. >> >> Add support for MTE asynchronous mode. >> >> The exception handling mechanism will be added with a future patch. >> >> Note: KASAN HW activates async mode via kasan.mode kernel parameter. >> The default mode is set to synchronous. >> The code that verifies the status of TFSR_EL1 will be added with a >> future patch. >> >> Cc: Catalin Marinas >> Cc: Will Deacon >> Reviewed-by: Catalin Marinas >> Reviewed-by: Andrey Konovalov >> Signed-off-by: Vincenzo Frascino >> --- >> arch/arm64/include/asm/memory.h | 3 ++- >> arch/arm64/include/asm/mte-kasan.h | 9 +++++++-- >> arch/arm64/kernel/mte.c | 19 ++++++++++++++++--- >> 3 files changed, 25 insertions(+), 6 deletions(-) >> >> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h >> index c759faf7a1ff..91515383d763 100644 >> --- a/arch/arm64/include/asm/memory.h >> +++ b/arch/arm64/include/asm/memory.h >> @@ -243,7 +243,8 @@ 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_sync() mte_enable_kernel_sync() >> +#define arch_enable_tagging_async() mte_enable_kernel_async() > > We need to update KASAN usage of arch_enable_tagging() to > arch_enable_tagging_sync() in this patch as well. Otherwise, this > leaves KASAN broken between this patch and the next one. > Yes you are right, still can't explain why it did bysect cleanly though. I will introduce temporarily here: #define arch_enable_tagging() arch_enable_tagging_sync() and remove it again in the respective kasan patch. > >> #define arch_set_tagging_report_once(state) mte_set_report_once(state) >> #define arch_init_tags(max_tag) mte_init_tags(max_tag) >> #define arch_get_random_tag() mte_get_random_tag() >> diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h >> index 7ab500e2ad17..4acf8bf41cad 100644 >> --- a/arch/arm64/include/asm/mte-kasan.h >> +++ b/arch/arm64/include/asm/mte-kasan.h >> @@ -77,7 +77,8 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag) >> } while (curr != end); >> } >> >> -void mte_enable_kernel(void); >> +void mte_enable_kernel_sync(void); >> +void mte_enable_kernel_async(void); >> void mte_init_tags(u64 max_tag); >> >> void mte_set_report_once(bool state); >> @@ -104,7 +105,11 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag) >> { >> } >> >> -static inline void mte_enable_kernel(void) >> +static inline void mte_enable_kernel_sync(void) >> +{ >> +} >> + >> +static inline void mte_enable_kernel_async(void) >> { >> } >> >> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c >> index a66c2806fc4d..706b7ab75f31 100644 >> --- a/arch/arm64/kernel/mte.c >> +++ b/arch/arm64/kernel/mte.c >> @@ -107,13 +107,26 @@ void mte_init_tags(u64 max_tag) >> write_sysreg_s(SYS_GCR_EL1_RRND | gcr_kernel_excl, SYS_GCR_EL1); >> } >> >> -void mte_enable_kernel(void) >> +static inline void __mte_enable_kernel(const char *mode, unsigned long tcf) >> { >> /* Enable MTE Sync Mode for EL1. */ >> - sysreg_clear_set(sctlr_el1, SCTLR_ELx_TCF_MASK, SCTLR_ELx_TCF_SYNC); >> + sysreg_clear_set(sctlr_el1, SCTLR_ELx_TCF_MASK, tcf); >> isb(); >> + >> + pr_info_once("MTE: enabled in %s mode at EL1\n", mode); >> +} >> + >> +void mte_enable_kernel_sync(void) >> +{ >> + __mte_enable_kernel("synchronous", SCTLR_ELx_TCF_SYNC); >> +} >> +EXPORT_SYMBOL_GPL(mte_enable_kernel_sync); >> + >> +void mte_enable_kernel_async(void) >> +{ >> + __mte_enable_kernel("asynchronous", SCTLR_ELx_TCF_ASYNC); >> } >> -EXPORT_SYMBOL_GPL(mte_enable_kernel); >> +EXPORT_SYMBOL_GPL(mte_enable_kernel_async); >> >> void mte_set_report_once(bool state) >> { >> -- >> 2.30.0 >> -- Regards, Vincenzo