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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 98431C0044D for ; Mon, 16 Mar 2020 10:28:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76E13205ED for ; Mon, 16 Mar 2020 10:28:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730565AbgCPK2v (ORCPT ); Mon, 16 Mar 2020 06:28:51 -0400 Received: from foss.arm.com ([217.140.110.172]:45530 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730550AbgCPK2v (ORCPT ); Mon, 16 Mar 2020 06:28:51 -0400 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 Cc: Catalin Marinas , linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, clang-built-linux@googlegroups.com, x86@kernel.org, Will Deacon , Arnd Bergmann , Russell King , Paul Burton , Thomas Gleixner , Andy Lutomirski , Ingo Molnar , Borislav Petkov , Stephen Boyd , Mark Salyzyn , Kees Cook , Peter Collingbourne , Dmitry Safonov <0x7f454c46@gmail.com>, Andrei Vagin , Nick Desaulniers , Marc Zyngier , Will Deacon 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-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.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