Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755285AbZGNRO2 (ORCPT ); Tue, 14 Jul 2009 13:14:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754817AbZGNRO1 (ORCPT ); Tue, 14 Jul 2009 13:14:27 -0400 Received: from smtp.gentoo.org ([140.211.166.183]:59962 "EHLO smtp.gentoo.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754687AbZGNRO1 (ORCPT ); Tue, 14 Jul 2009 13:14:27 -0400 From: Mike Frysinger To: linux-kernel@vger.kernel.org Cc: uclinux-dist-devel@blackfin.uclinux.org, Bernd Schmidt , Bryan Wu , David Howells Subject: [PATCH v2] NOMMU: add support for Memory Protection Units (MPU) Date: Tue, 14 Jul 2009 13:14:25 -0400 Message-Id: <1247591665-12000-1-git-send-email-vapier@gentoo.org> X-Mailer: git-send-email 1.6.3.3 In-Reply-To: <20090714161416.GA19147@cmpxchg.org> References: <20090714161416.GA19147@cmpxchg.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3113 Lines: 106 From: Bernd Schmidt Some architectures (like the Blackfin arch) implement some of the "simpler" features that one would expect out of a MMU such as memory protection. In our case, we actually get read/write/exec protection down to the page boundary so processes can't stomp on each other let alone the kernel. There is a performance decrease (which depends greatly on the workload) however as the hardware/software interaction was not optimized at design time. Signed-off-by: Bernd Schmidt Signed-off-by: Bryan Wu Signed-off-by: Mike Frysinger CC: David Howells --- v2 - unify mpu code in nommu.c to simplify things kernel/module.c | 5 +++++ mm/nommu.c | 21 +++++++++++++++++++++ 2 files changed, 26 insertions(+), 0 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index e797812..80036bc 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -46,6 +46,7 @@ #include #include #include +#include #include #include #include @@ -1506,6 +1507,10 @@ static void free_module(struct module *mod) /* Finally, free the core (containing the module structure) */ module_free(mod, mod->module_core); + +#ifdef CONFIG_MPU + update_protections(current->mm); +#endif } void *__symbol_get(const char *symbol) diff --git a/mm/nommu.c b/mm/nommu.c index b571ef7..e7c3bbe 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -33,6 +33,7 @@ #include #include #include +#include #include "internal.h" static inline __attribute__((format(printf, 1, 2))) @@ -608,6 +609,22 @@ static void put_nommu_region(struct vm_region *region) } /* + * update protection on a vma + */ +static void protect_vma(struct vm_area_struct *vma, unsigned long flags) +{ +#ifdef CONFIG_MPU + struct mm_struct *mm = vma->vm_mm; + long start = vma->vm_start & PAGE_MASK; + while (start < vma->vm_end) { + protect_page(mm, start, flags); + start += PAGE_SIZE; + } + update_protections(mm); +#endif +} + +/* * add a VMA into a process's mm_struct in the appropriate place in the list * and tree and add to the address space's page tree also if not an anonymous * page @@ -626,6 +643,8 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) mm->map_count++; vma->vm_mm = mm; + protect_vma(vma, vma->vm_flags); + /* add the VMA to the mapping */ if (vma->vm_file) { mapping = vma->vm_file->f_mapping; @@ -688,6 +707,8 @@ static void delete_vma_from_mm(struct vm_area_struct *vma) kenter("%p", vma); + protect_vma(vma, 0); + mm->map_count--; if (mm->mmap_cache == vma) mm->mmap_cache = NULL; -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/