From a0a8f5364a5ad248aec6cb705e0092ff563edc2f Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 25 Jul 2008 19:45:20 -0700 Subject: [PATCH] x86: implement pte_special 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). [hugh@veritas.com: fix a BUG] Signed-off-by: Nick Piggin Cc: Dave Kleikamp Cc: Andy Whitcroft Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Andi Kleen Cc: Dave Kleikamp Cc: Badari Pulavarty Cc: Zach Brown Cc: Jens Axboe Reviewed-by: Peter Zijlstra Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-x86/pgtable.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/include/asm-x86/pgtable.h b/include/asm-x86/pgtable.h index 3e5dbc4..04caa2f 100644 --- a/include/asm-x86/pgtable.h +++ b/include/asm-x86/pgtable.h @@ -18,6 +18,7 @@ #define _PAGE_BIT_UNUSED2 10 #define _PAGE_BIT_UNUSED3 11 #define _PAGE_BIT_PAT_LARGE 12 /* On 2MB or 1GB pages */ +#define _PAGE_BIT_SPECIAL _PAGE_BIT_UNUSED1 #define _PAGE_BIT_NX 63 /* No execute: only valid after cpuid check */ #define _PAGE_PRESENT (_AT(pteval_t, 1) << _PAGE_BIT_PRESENT) @@ -34,6 +35,8 @@ #define _PAGE_UNUSED3 (_AT(pteval_t, 1) << _PAGE_BIT_UNUSED3) #define _PAGE_PAT (_AT(pteval_t, 1) << _PAGE_BIT_PAT) #define _PAGE_PAT_LARGE (_AT(pteval_t, 1) << _PAGE_BIT_PAT_LARGE) +#define _PAGE_SPECIAL (_AT(pteval_t, 1) << _PAGE_BIT_SPECIAL) +#define __HAVE_ARCH_PTE_SPECIAL #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) #define _PAGE_NX (_AT(pteval_t, 1) << _PAGE_BIT_NX) @@ -54,7 +57,7 @@ /* Set of bits not changed in pte_modify */ #define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \ - _PAGE_ACCESSED | _PAGE_DIRTY) + _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY) #define _PAGE_CACHE_MASK (_PAGE_PCD | _PAGE_PWT) #define _PAGE_CACHE_WB (0) @@ -180,7 +183,7 @@ 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) @@ -246,7 +249,7 @@ static inline pte_t pte_clrglobal(pte_t pte) static inline pte_t pte_mkspecial(pte_t pte) { - return pte; + return __pte(pte_val(pte) | _PAGE_SPECIAL); } extern pteval_t __supported_pte_mask; -- 2.7.4