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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jDmzN-00064w-Mt; Mon, 16 Mar 2020 10:28:53 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jDmzK-00064E-N6 for linux-arm-kernel@lists.infradead.org; Mon, 16 Mar 2020 10:28:52 +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 236D31FB; Mon, 16 Mar 2020 03:28:50 -0700 (PDT) Received: from [10.37.9.38] (unknown [10.37.9.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E38D43F534; Mon, 16 Mar 2020 03:28:45 -0700 (PDT) Subject: Re: [PATCH v3 18/26] arm64: Introduce asm/vdso/processor.h To: Mark Rutland References: <20200313154345.56760-1-vincenzo.frascino@arm.com> <20200313154345.56760-19-vincenzo.frascino@arm.com> <20200315182950.GB32205@mbp> <20200316102214.GA5746@lakrids.cambridge.arm.com> From: Vincenzo Frascino Message-ID: Date: Mon, 16 Mar 2020 10:29:13 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200316102214.GA5746@lakrids.cambridge.arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200316_032850_798149_85FED159 X-CRM114-Status: GOOD ( 19.65 ) 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: Catalin Marinas , Dmitry Safonov <0x7f454c46@gmail.com>, linux-mips@vger.kernel.org, Will Deacon , linux-arch@vger.kernel.org, Marc Zyngier , x86@kernel.org, Russell King , clang-built-linux@googlegroups.com, Ingo Molnar , Kees Cook , Arnd Bergmann , Will Deacon , Borislav Petkov , Andy Lutomirski , Thomas Gleixner , Peter Collingbourne , linux-arm-kernel@lists.infradead.org, Andrei Vagin , Stephen Boyd , Nick Desaulniers , linux-kernel@vger.kernel.org, Mark Salyzyn , Paul Burton Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 3/16/20 10:22 AM, Mark Rutland wrote: > Hi Vincenzo, > > On Mon, Mar 16, 2020 at 09:42:32AM +0000, Vincenzo Frascino wrote: >> On 3/15/20 6:30 PM, Catalin Marinas wrote: >>> On Fri, Mar 13, 2020 at 03:43:37PM +0000, Vincenzo Frascino wrote: >>>> --- /dev/null >>>> +++ b/arch/arm64/include/asm/vdso/processor.h >>>> @@ -0,0 +1,31 @@ >>>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>>> +/* >>>> + * Copyright (C) 2020 ARM Ltd. >>>> + */ >>>> +#ifndef __ASM_VDSO_PROCESSOR_H >>>> +#define __ASM_VDSO_PROCESSOR_H >>>> + >>>> +#ifndef __ASSEMBLY__ >>>> + >>>> +#include >>>> + >>>> +#ifdef CONFIG_COMPAT >>>> +#if defined(CONFIG_ARM64_64K_PAGES) && defined(CONFIG_KUSER_HELPERS) >>>> +/* >>>> + * With CONFIG_ARM64_64K_PAGES enabled, the last page is occupied >>>> + * by the compat vectors page. >>>> + */ >>>> +#define TASK_SIZE_32 UL(0x100000000) >>>> +#else >>>> +#define TASK_SIZE_32 (UL(0x100000000) - PAGE_SIZE) >>>> +#endif /* CONFIG_ARM64_64K_PAGES */ >>>> +#endif /* CONFIG_COMPAT */ >>> >>> Just curious, what's TASK_SIZE_32 used for in the vDSO code? You don't >>> seem to move TASK_SIZE. >>> >> >> I tried to fine grain the headers as much as I could in order to avoid >> unneeded/unwanted inclusions: >> * TASK_SIZE_32 is used to verify ABI consistency on vdso32 (please refer to >> arch/arm64/kernel/vdso32/vgettimeofday.c). >> * TASK_SIZE is not required by the vdso library hence it is not present in >> these headers. > > It would be worth noting the former point in the commit message, since > it can be surprising. > Sure it is a good point, I will add this to the commit message. > I also think it's worth keeping the definitions together if that's easy, > as it makes it easier to navigate the codebase, even if TASK_SIZE isn't > necessary for the VDSO itself. This can't be done because TASK_SIZE on arm64 requires test_thread_flag() with is not suited for vDSO. In other words can cause the same problem we are trying to solve. > > Thanks, > Mark. > -- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel