From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753258AbcKARLO (ORCPT ); Tue, 1 Nov 2016 13:11:14 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:49538 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751414AbcKARLM (ORCPT ); Tue, 1 Nov 2016 13:11:12 -0400 DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org 24408614A1 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=pass smtp.mailfrom=cov@codeaurora.org From: Christopher Covington To: criu@openvz.org, Will Deacon , linux-mm@kvack.org, Laurent Dufour Cc: Christopher Covington , Arnd Bergmann , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC v2 1/7] mm: Provide generic VDSO unmap and remap functions Date: Tue, 1 Nov 2016 11:10:55 -0600 Message-Id: <20161101171101.24704-1-cov@codeaurora.org> X-Mailer: git-send-email 2.9.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When Address Space Layout Randomization (ASLR, randmaps) is enabled, the address of the VDSO fluctuates from one process to the next. If Checkpoint/Restore In Userspace (CRIU) is to fully replicate the memory map of a previous process, it must be able to remap the VDSO of a new process to the address used by the previous process. Historically this has been implemented in architecture-specific code for PowerPC and x86. In order to support 32-bit and 64-bit ARM without further duplication of code, copy Laurent Dufour's implementation for PowerPC with slight modifications to a generic location. This is hopefully the beginning of a long process of VDSO code de-duplication between architectures. Signed-off-by: Christopher Covington --- include/asm-generic/mm_hooks.h | 35 ++++++++++++++++++++++++++++++++--- 1 file changed, 32 insertions(+), 3 deletions(-) diff --git a/include/asm-generic/mm_hooks.h b/include/asm-generic/mm_hooks.h index cc5d9a1..73f09f1 100644 --- a/include/asm-generic/mm_hooks.h +++ b/include/asm-generic/mm_hooks.h @@ -1,7 +1,17 @@ /* - * Define generic no-op hooks for arch_dup_mmap, arch_exit_mmap - * and arch_unmap to be included in asm-FOO/mmu_context.h for any - * arch FOO which doesn't need to hook these. + * Define generic hooks for arch_dup_mmap, arch_exit_mmap and arch_unmap to be + * included in asm-FOO/mmu_context.h for any arch FOO which doesn't need to + * specially hook these. + * + * arch_remap originally from include/linux-mm-arch-hooks.h + * arch_unmap originally from arch/powerpc/include/asm/mmu_context.h + * Copyright (C) 2015, IBM Corporation + * Author: Laurent Dufour + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * */ #ifndef _ASM_GENERIC_MM_HOOKS_H #define _ASM_GENERIC_MM_HOOKS_H @@ -19,6 +29,25 @@ static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long start, unsigned long end) { +#ifdef CONFIG_GENERIC_VDSO + if (start <= mm->context.vdso && mm->context.vdso < end) + mm->context.vdso = 0; +#endif /* CONFIG_GENERIC_VDSO */ +} + +static inline void arch_remap(struct mm_struct *mm, + unsigned long old_start, unsigned long old_end, + unsigned long new_start, unsigned long new_end) +{ +#ifdef CONFIG_GENERIC_VDSO + /* + * mremap() doesn't allow moving multiple vmas so we can limit the + * check to old_addr == vdso. + */ + if (old_addr == mm->context.vdso) + mm->context.vdso = new_addr; + +#endif /* CONFIG_GENERIC_VDSO */ } static inline void arch_bprm_mm_init(struct mm_struct *mm, -- Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.