From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 26 Jul 2006 21:39:49 +0100 (BST) From: Hugh Dickins Subject: Re: [PATCH] vm/agp: remove private page protection map In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Airlie Cc: Andrew Morton , Dave Jones , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tue, 18 Jul 2006, Dave Airlie wrote: > AGP keeps its own copy of the protection_map, upcoming DRM changes > will also require access to this map from modules. I'm happy with the intent of your vm_get_page_prot() patch (and would like to extend it to other places after, minimizing references to the protection_map[]). But there's a few aspects which distress me - the u8 type nowhere else in mm, the requirement that caller mask the arg, agp_convert_mmap_flags still using its own conversion from PROT_ to VM_ while there's an inline in mm.h (though why someone thought to optimize and so obscure that version puzzles me!). Would you be happy to insert your Sign-off in the replacement below? AGP keeps its own copy of the protection_map, upcoming DRM changes will also require access to this map from modules. Signed-off-by: Hugh Dickins --- drivers/char/agp/frontend.c | 27 ++------------------------- include/linux/mm.h | 1 + mm/mmap.c | 7 +++++++ 3 files changed, 10 insertions(+), 25 deletions(-) --- 2.6.18-rc2-git6/drivers/char/agp/frontend.c 2006-07-16 00:17:07.000000000 +0100 +++ linux/drivers/char/agp/frontend.c 2006-07-26 20:32:10.000000000 +0100 @@ -151,35 +151,12 @@ static void agp_add_seg_to_client(struct client->segments = seg; } -/* Originally taken from linux/mm/mmap.c from the array - * protection_map. - * The original really should be exported to modules, or - * some routine which does the conversion for you - */ - -static const pgprot_t my_protect_map[16] = -{ - __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, - __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 -}; - static pgprot_t agp_convert_mmap_flags(int prot) { -#define _trans(x,bit1,bit2) \ -((bit1==bit2)?(x&bit1):(x&bit1)?bit2:0) - unsigned long prot_bits; - pgprot_t temp; - - prot_bits = _trans(prot, PROT_READ, VM_READ) | - _trans(prot, PROT_WRITE, VM_WRITE) | - _trans(prot, PROT_EXEC, VM_EXEC); - - prot_bits |= VM_SHARED; - temp = my_protect_map[prot_bits & 0x0000000f]; - - return temp; + prot_bits = calc_vm_prot_bits(prot) | VM_SHARED; + return vm_get_page_prot(prot_bits); } static int agp_create_segment(struct agp_client *client, struct agp_region *region) --- 2.6.18-rc2-git6/include/linux/mm.h 2006-07-16 00:17:31.000000000 +0100 +++ linux/include/linux/mm.h 2006-07-26 20:33:59.000000000 +0100 @@ -1012,6 +1012,7 @@ static inline unsigned long vma_pages(st return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; } +pgprot_t vm_get_page_prot(unsigned long vm_flags); struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr); struct page *vmalloc_to_page(void *addr); unsigned long vmalloc_to_pfn(void *addr); --- 2.6.18-rc2-git6/mm/mmap.c 2006-07-16 00:17:39.000000000 +0100 +++ linux/mm/mmap.c 2006-07-26 20:40:12.000000000 +0100 @@ -60,6 +60,13 @@ pgprot_t protection_map[16] = { __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 }; +pgprot_t vm_get_page_prot(unsigned long vm_flags) +{ + return protection_map[vm_flags & + (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; +} +EXPORT_SYMBOL(vm_get_page_prot); + int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ int sysctl_overcommit_ratio = 50; /* default is 50% */ int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org