From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 21 May 2008 13:59:29 +0200 From: Nick Piggin Subject: [patch 1/2] x86: implement pte_special Message-ID: <20080521115929.GB9030@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: shaggy@austin.ibm.com, axboe@oracle.com, torvalds@linux-foundation.org, linux-mm@kvack.org, linux-arch@vger.kernel.org List-ID: Implement the pte_special bit for x86. This is required to support lockless get_user_pages, because we need to know whether or not we can refcount a particular page given only its pte (and no vma). Signed-off-by: Nick Piggin Cc: shaggy@austin.ibm.com Cc: axboe@oracle.com Cc: torvalds@linux-foundation.org Cc: linux-mm@kvack.org Cc: linux-arch@vger.kernel.org --- Index: linux-2.6/include/asm-x86/pgtable.h =================================================================== --- linux-2.6.orig/include/asm-x86/pgtable.h +++ linux-2.6/include/asm-x86/pgtable.h @@ -17,6 +17,7 @@ #define _PAGE_BIT_UNUSED1 9 /* available for programmer */ #define _PAGE_BIT_UNUSED2 10 #define _PAGE_BIT_UNUSED3 11 +#define _PAGE_BIT_SPECIAL _PAGE_BIT_UNUSED1 #define _PAGE_BIT_PAT_LARGE 12 /* On 2MB or 1GB pages */ #define _PAGE_BIT_NX 63 /* No execute: only valid after cpuid check */ @@ -39,6 +40,8 @@ #define _PAGE_UNUSED3 (_AC(1, L)<<_PAGE_BIT_UNUSED3) #define _PAGE_PAT (_AC(1, L)<<_PAGE_BIT_PAT) #define _PAGE_PAT_LARGE (_AC(1, L)<<_PAGE_BIT_PAT_LARGE) +#define _PAGE_SPECIAL (_AC(1, L)<<_PAGE_BIT_SPECIAL) +#define __HAVE_ARCH_PTE_SPECIAL #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) #define _PAGE_NX (_AC(1, ULL) << _PAGE_BIT_NX) @@ -198,7 +201,7 @@ static inline int pte_exec(pte_t pte) static inline int pte_special(pte_t pte) { - return 0; + return pte_val(pte) & _PAGE_SPECIAL; } static inline int pmd_large(pmd_t pte) @@ -264,7 +267,7 @@ static inline pte_t pte_clrglobal(pte_t static inline pte_t pte_mkspecial(pte_t pte) { - return pte; + return __pte(pte_val(pte) | _PAGE_SPECIAL); } extern pteval_t __supported_pte_mask; -- 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