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: 9333677 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E50FE6077A for ; Thu, 15 Sep 2016 13:50:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CDE7A29085 for ; Thu, 15 Sep 2016 13:50:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C2706295A3; Thu, 15 Sep 2016 13:50:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 8C4862959F for ; Thu, 15 Sep 2016 13:50:04 +0000 (UTC) Received: (qmail 11397 invoked by uid 550); 15 Sep 2016 13:50:03 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 11361 invoked from network); 15 Sep 2016 13:50:01 -0000 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 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> Subject: [kernel-hardening] [RFC PATCH 2/8] thread_info: allow custom in-task thread_info X-Virus-Scanned: ClamAV using ClamSMTP 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(-) 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