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=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 DA98DC432C3 for ; Fri, 12 Mar 2021 15:46:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF54C65046 for ; Fri, 12 Mar 2021 15:46:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233171AbhCLPpq (ORCPT ); Fri, 12 Mar 2021 10:45:46 -0500 Received: from foss.arm.com ([217.140.110.172]:55982 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232375AbhCLPoV (ORCPT ); Fri, 12 Mar 2021 10:44:21 -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 EF6851FB; Fri, 12 Mar 2021 07:44:20 -0800 (PST) Received: from [10.37.8.6] (unknown [10.37.8.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 02E3A3F7D7; Fri, 12 Mar 2021 07:44:18 -0800 (PST) Subject: Re: [PATCH v15 5/8] arm64: mte: Enable TCO in functions that can read beyond buffer limits To: Catalin Marinas Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Andrew Morton , Will Deacon , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Andrey Konovalov , Lorenzo Pieralisi References: <20210312142210.21326-1-vincenzo.frascino@arm.com> <20210312142210.21326-6-vincenzo.frascino@arm.com> <20210312151259.GB24210@arm.com> <31b7a388-4c57-cb25-2d30-da7c37e2b4d6@arm.com> <20210312152927.GD24210@arm.com> From: Vincenzo Frascino Message-ID: Date: Fri, 12 Mar 2021 15:44:17 +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: <20210312152927.GD24210@arm.com> 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 3/12/21 3:29 PM, Catalin Marinas wrote: > On Fri, Mar 12, 2021 at 03:23:44PM +0000, Vincenzo Frascino wrote: >> On 3/12/21 3:13 PM, Catalin Marinas wrote: >>> On Fri, Mar 12, 2021 at 02:22:07PM +0000, Vincenzo Frascino wrote: >>>> diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h >>>> index 9b557a457f24..8603c6636a7d 100644 >>>> --- a/arch/arm64/include/asm/mte.h >>>> +++ b/arch/arm64/include/asm/mte.h >>>> @@ -90,5 +90,20 @@ static inline void mte_assign_mem_tag_range(void *addr, size_t size) >>>> >>>> #endif /* CONFIG_ARM64_MTE */ >>>> >>>> +#ifdef CONFIG_KASAN_HW_TAGS >>>> +/* Whether the MTE asynchronous mode is enabled. */ >>>> +DECLARE_STATIC_KEY_FALSE(mte_async_mode); >>>> + >>>> +static inline bool system_uses_mte_async_mode(void) >>>> +{ >>>> + return static_branch_unlikely(&mte_async_mode); >>>> +} >>>> +#else >>>> +static inline bool system_uses_mte_async_mode(void) >>>> +{ >>>> + return false; >>>> +} >>>> +#endif /* CONFIG_KASAN_HW_TAGS */ >>> >>> You can write this with fewer lines: >>> >>> DECLARE_STATIC_KEY_FALSE(mte_async_mode); >>> >>> static inline bool system_uses_mte_async_mode(void) >>> { >>> return IS_ENABLED(CONFIG_KASAN_HW_TAGS) && >>> static_branch_unlikely(&mte_async_mode); >>> } >>> >>> The compiler will ensure that mte_async_mode is not referred when >>> !CONFIG_KASAN_HW_TAGS and therefore doesn't need to be defined. >> >> Yes, I agree, but I introduce "#ifdef CONFIG_KASAN_HW_TAGS" in the successive >> patch anyway, according to me the overall code looks more uniform like this. But >> I do not have a strong opinion or preference on this. > > Ah, yes, I didn't look at patch 6 again as it was already reviewed and I > forgot the context. Leave it as it is then, my reviewed-by still stands. > Ok, thanks. -- Regards, Vincenzo