From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932713AbcIUB1C (ORCPT ); Tue, 20 Sep 2016 21:27:02 -0400 Received: from mail-yw0-f171.google.com ([209.85.161.171]:33454 "EHLO mail-yw0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932393AbcIUB07 (ORCPT ); Tue, 20 Sep 2016 21:26:59 -0400 Subject: Re: [RFC PATCH 0/8] arm64: move thread_info off of the task stack To: Mark Rutland , linux-arm-kernel@lists.infradead.org References: <1473947349-14521-1-git-send-email-mark.rutland@arm.com> 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, suzuki.poulose@arm.com, takahiro.akashi@linaro.org, will.deacon@arm.com, kernel-hardening@lists.openwall.com From: Laura Abbott Message-ID: Date: Tue, 20 Sep 2016 18:26:54 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <1473947349-14521-1-git-send-email-mark.rutland@arm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/15/2016 06:49 AM, Mark Rutland wrote: > Building atop of Andy's work on x86 and generic code, these patches move > arm64's thread_info off of the stack and into task_struct. This protects > thread_info from corruption in the face of stack overflow, and serves as > a step towards fully robust stack overflow handling will be addressed by > subsequent patches. > > In contrast to x86, we can't place some critical data such as > preempt_count in percpu variables, and we must store these in some > per-task location. This, compounded with the way headers are organised > conspires to require us to still define our own thread_info. I > understand that the longer term plan is to kill off thread_info > entirely, hence I'm sending this as an RFC so we can figure out if/how > we can achieve that. > > These patches are based on Andy's x86/vmap_stack branch [1,2], and I've > pushed a copy to me arm64/ti-stack-split branch [3,4]. The result of > these patches boots happily on platforms within reach of my desk, but > has not seen much stressing so far. > FWIW, I used your ti-stack-split branch while running some kernel builds and it seems to work well enough. You can take that as a Tested-by or I can re-test with a non-RFC version. > Thanks, > Mark. > > [1] git://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git x86/vmap_stack > [2] https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/log/?h=x86/vmap_stack > [3] git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git arm64/ti-stack-split > [4] https://git.kernel.org/cgit/linux/kernel/git/mark/linux.git/log/?h=arm64/ti-stack-split > > Mark Rutland (8): > thread_info: include for THREAD_INFO_IN_TASK > thread_info: allow custom in-task thread_info > arm64: thread_info remove stale items > arm64: asm-offsets: remove unused definitions > arm64: assembler: introduce ldr_this_cpu > arm64: traps: use task_struct instead of thread_info > arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx > arm64: split thread_info from task stack > > arch/arm64/Kconfig | 2 ++ > arch/arm64/include/asm/Kbuild | 1 - > arch/arm64/include/asm/assembler.h | 19 +++++++++++++++---- > arch/arm64/include/asm/current.h | 22 ++++++++++++++++++++++ > arch/arm64/include/asm/smp.h | 1 + > arch/arm64/include/asm/suspend.h | 2 +- > arch/arm64/include/asm/thread_info.h | 21 --------------------- > arch/arm64/kernel/asm-offsets.c | 3 +-- > arch/arm64/kernel/entry.S | 6 +++--- > arch/arm64/kernel/head.S | 11 +++++------ > arch/arm64/kernel/process.c | 31 ++++++++++++++++++++++++++----- > arch/arm64/kernel/sleep.S | 3 --- > arch/arm64/kernel/smp.c | 2 ++ > arch/arm64/kernel/stacktrace.c | 5 +++++ > arch/arm64/kernel/suspend.c | 6 ------ > arch/arm64/kernel/traps.c | 12 ++++++------ > arch/arm64/mm/proc.S | 6 ++++++ > include/linux/thread_info.h | 4 +++- > init/Kconfig | 3 +++ > 19 files changed, 101 insertions(+), 59 deletions(-) > create mode 100644 arch/arm64/include/asm/current.h >