Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755319AbZGNQOx (ORCPT ); Tue, 14 Jul 2009 12:14:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755253AbZGNQOw (ORCPT ); Tue, 14 Jul 2009 12:14:52 -0400 Received: from cmpxchg.org ([85.214.51.133]:48912 "EHLO cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755018AbZGNQOw (ORCPT ); Tue, 14 Jul 2009 12:14:52 -0400 Date: Tue, 14 Jul 2009 18:14:16 +0200 From: Johannes Weiner To: Mike Frysinger Cc: linux-kernel@vger.kernel.org, uclinux-dist-devel@blackfin.uclinux.org, Bernd Schmidt , Bryan Wu , David Howells Subject: Re: [PATCH] NOMMU: add support for Memory Protection Units (MPU) Message-ID: <20090714161416.GA19147@cmpxchg.org> References: <1247581340-20031-1-git-send-email-vapier@gentoo.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1247581340-20031-1-git-send-email-vapier@gentoo.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3267 Lines: 105 On Tue, Jul 14, 2009 at 10:22:20AM -0400, Mike Frysinger wrote: > 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 > --- > kernel/module.c | 5 +++++ > mm/nommu.c | 25 +++++++++++++++++++++++++ > 2 files changed, 30 insertions(+), 0 deletions(-) > > diff --git a/kernel/module.c b/kernel/module.c > index 0a04983..e1a3dfc 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -47,6 +47,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -1519,6 +1520,10 @@ 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 53cab10..a0269e5 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))) > @@ -640,11 +641,23 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) > struct vm_area_struct *pvma, **pp; > struct address_space *mapping; > struct rb_node **p, *parent; > +#ifdef CONFIG_MPU > + long start; > +#endif > > kenter(",%p", vma); > > BUG_ON(!vma->vm_region); > > +#ifdef CONFIG_MPU > + start = vma->vm_start & PAGE_MASK; > + while (start < vma->vm_end) { > + protect_page(mm, start, vma->vm_flags); > + start += PAGE_SIZE; > + } > + update_protections(mm); > +#endif > + > mm->map_count++; > vma->vm_mm = mm; > > @@ -707,9 +720,21 @@ static void delete_vma_from_mm(struct vm_area_struct *vma) > struct vm_area_struct **pp; > struct address_space *mapping; > struct mm_struct *mm = vma->vm_mm; > +#ifdef CONFIG_MPU > + long start; > +#endif > > kenter("%p", vma); > > +#ifdef CONFIG_MPU > + start = vma->vm_start & PAGE_MASK; > + while (start < vma->vm_end) { > + protect_page(mm, start, 0); > + start += PAGE_SIZE; > + } > + update_protections(mm); > +#endif How about refactoring that into one function? Saves all but one #ifdef. -- 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/