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,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 ECCDFC433E6 for ; Fri, 12 Mar 2021 15:13:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B28406500B for ; Fri, 12 Mar 2021 15:13:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232229AbhCLPNM (ORCPT ); Fri, 12 Mar 2021 10:13:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:45746 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232032AbhCLPNF (ORCPT ); Fri, 12 Mar 2021 10:13:05 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A5C7964FD9; Fri, 12 Mar 2021 15:13:02 +0000 (UTC) Date: Fri, 12 Mar 2021 15:13:00 +0000 From: Catalin Marinas To: Vincenzo Frascino 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 Subject: Re: [PATCH v15 5/8] arm64: mte: Enable TCO in functions that can read beyond buffer limits Message-ID: <20210312151259.GB24210@arm.com> References: <20210312142210.21326-1-vincenzo.frascino@arm.com> <20210312142210.21326-6-vincenzo.frascino@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210312142210.21326-6-vincenzo.frascino@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c > index fa755cf94e01..9362928ba0d5 100644 > --- a/arch/arm64/kernel/mte.c > +++ b/arch/arm64/kernel/mte.c > @@ -26,6 +26,10 @@ u64 gcr_kernel_excl __ro_after_init; > > static bool report_fault_once = true; > > +/* Whether the MTE asynchronous mode is enabled. */ > +DEFINE_STATIC_KEY_FALSE(mte_async_mode); > +EXPORT_SYMBOL_GPL(mte_async_mode); Maybe keep these bracketed by #ifdef CONFIG_KASAN_HW_TAGS. I think the mte_enable_kernel_*() aren't needed either if KASAN_HW is disabled (you can do it with an additional patch). With these, you can add: Reviewed-by: Catalin Marinas