From patchwork Thu Sep 15 13:49:03 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 76312 Delivered-To: patch@linaro.org Received: by 10.140.106.72 with SMTP id d66csp2454011qgf; Thu, 15 Sep 2016 06:50:22 -0700 (PDT) X-Received: by 10.98.22.212 with SMTP id 203mr14832013pfw.74.1473947422878; Thu, 15 Sep 2016 06:50:22 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id o192si3701394pfg.228.2016.09.15.06.50.22; Thu, 15 Sep 2016 06:50:22 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934060AbcIONuH (ORCPT + 27 others); Thu, 15 Sep 2016 09:50:07 -0400 Received: from foss.arm.com ([217.140.101.70]:36964 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932974AbcIONtz (ORCPT ); Thu, 15 Sep 2016 09:49:55 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8FC8F687; Thu, 15 Sep 2016 06:49:49 -0700 (PDT) Received: from leverpostej.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 710F13F21A; Thu, 15 Sep 2016 06:49:47 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: akpm@linux-foundation.org, ard.biesheuvel@linaro.org, catalin.marinas@arm.com, james.morse@arm.com, keescook@chromium.org, linux-kernel@vger.kernel.org, lorenzo.pieralisi@arm.com, luto@kernel.org, mark.rutland@arm.com, suzuki.poulose@arm.com, takahiro.akashi@linaro.org, will.deacon@arm.com, kernel-hardening@lists.openwall.com Subject: [RFC PATCH 2/8] thread_info: allow custom in-task thread_info Date: Thu, 15 Sep 2016 14:49:03 +0100 Message-Id: <1473947349-14521-3-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1473947349-14521-1-git-send-email-mark.rutland@arm.com> References: <1473947349-14521-1-git-send-email-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, task_struct is defined in , which (indirectly) pulls in a number of low-level arch headers such as through a number of other headers. Thus, code and structures in these headers can't rely on the definition of task_struct. Some of these headers are necessary for the definition of task_struct, so moving task_struct into its own header is insufficient tio avoid circular includes. With CONFIG_THREAD_INFO_IN_TASK, arch code needs to implement its own get_current() for the generic get_thread_info(). To avoid header dependency issues, this relies on thread_info being the first member of task_struct. This can be used by low-level arch code, as it doesn't depend on the definition of task_struct. For architectures without preempt-safe this_cpu ops, some data required by low-level arch code (e.g. preempt_count) has to be stored per-thread, and for the reasons above, we cannot place this in task_struct (or thread_struct, since we cannot know its offset from within task_struct). The only practical location for these is thread_info. This patch allows architectures with CONFIG_ARCH_HAS_OWN_THREAD_INFO to define their own thread_info, avoiding the problems described above. Signed-off-by: Mark Rutland Cc: Andrew Morton Cc: Andy Lutomirski Cc: Catalin Marinas Cc: Kees Cook Cc: Will Deacon Cc: linux-kernel@vger.kernel.org --- include/linux/thread_info.h | 3 ++- init/Kconfig | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) -- 1.9.1 diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index d9622f7..7984f87 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -13,7 +13,8 @@ struct timespec; struct compat_timespec; -#ifdef CONFIG_THREAD_INFO_IN_TASK +#if defined(CONFIG_THREAD_INFO_IN_TASK) && \ + !defined(CONFIG_ARCH_HAS_OWN_THREAD_INFO) struct thread_info { u32 flags; /* low level flags */ }; diff --git a/init/Kconfig b/init/Kconfig index 3b9a47f..f812098 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -26,6 +26,9 @@ config IRQ_WORK config BUILDTIME_EXTABLE_SORT bool +config ARCH_HAS_OWN_THREAD_INFO + bool + config THREAD_INFO_IN_TASK bool help