From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754824AbZA1Ebx (ORCPT ); Tue, 27 Jan 2009 23:31:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751632AbZA1Ebo (ORCPT ); Tue, 27 Jan 2009 23:31:44 -0500 Received: from hera.kernel.org ([140.211.167.34]:55433 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751541AbZA1Ebo (ORCPT ); Tue, 27 Jan 2009 23:31:44 -0500 Message-ID: <497FDFA7.8080402@kernel.org> Date: Wed, 28 Jan 2009 13:31:35 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Ingo Molnar , Linux Kernel Mailing List Subject: [PATCH 2/2 x86#stackprotector] x86: conditionalize stack canary handling in hot path References: <497FDF7C.8080706@kernel.org> In-Reply-To: <497FDF7C.8080706@kernel.org> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 28 Jan 2009 04:31:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Impact: no unnecessary stack canary swapping during context switch There's no point in moving stack_canary around during context switch if it's not enabled. Conditionalize it. Signed-off-by: Tejun Heo --- Ditto as the previous one. arch/x86/include/asm/system.h | 22 ++++++++++++++++------ 1 files changed, 16 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h index 8cadfe9..b77bd8b 100644 --- a/arch/x86/include/asm/system.h +++ b/arch/x86/include/asm/system.h @@ -86,17 +86,28 @@ do { \ , "rcx", "rbx", "rdx", "r8", "r9", "r10", "r11", \ "r12", "r13", "r14", "r15" +#ifdef CONFIG_CC_STACKPROTECTOR +#define __switch_canary \ + "movq %P[task_canary](%%rsi),%%r8\n\t" \ + "movq %%r8,%%gs:%P[pda_canary]\n\t" +#define __switch_canary_param \ + , [task_canary] "i" (offsetof(struct task_struct, stack_canary)) \ + , [pda_canary] "i" (offsetof(struct x8664_pda, stack_canary)) +#else /* CC_STACKPROTECTOR */ +#define __switch_canary +#define __switch_canary_param +#endif /* CC_STACKPROTECTOR */ + /* Save restore flags to clear handle leaking NT */ #define switch_to(prev, next, last) \ - asm volatile(SAVE_CONTEXT \ + asm volatile(SAVE_CONTEXT \ "movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */ \ "movq %P[threadrsp](%[next]),%%rsp\n\t" /* restore RSP */ \ "call __switch_to\n\t" \ ".globl thread_return\n" \ "thread_return:\n\t" \ "movq "__percpu_arg([current_task])",%%rsi\n\t" \ - "movq %P[task_canary](%%rsi),%%r8\n\t" \ - "movq %%r8,%%gs:%P[pda_canary]\n\t" \ + __switch_canary \ "movq %P[thread_info](%%rsi),%%r8\n\t" \ LOCK_PREFIX "btr %[tif_fork],%P[ti_flags](%%r8)\n\t" \ "movq %%rax,%%rdi\n\t" \ @@ -108,9 +119,8 @@ do { \ [ti_flags] "i" (offsetof(struct thread_info, flags)), \ [tif_fork] "i" (TIF_FORK), \ [thread_info] "i" (offsetof(struct task_struct, stack)), \ - [task_canary] "i" (offsetof(struct task_struct, stack_canary)),\ - [current_task] "m" (per_cpu_var(current_task)), \ - [pda_canary] "i" (offsetof(struct x8664_pda, stack_canary))\ + [current_task] "m" (per_cpu_var(current_task)) \ + __switch_canary_param \ : "memory", "cc" __EXTRA_CLOBBER) #endif -- 1.6.0.2