From: Nick Piggin 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: 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 Signed-off-by: Andrew Morton --- include/asm-x86/pgtable.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff -puN include/asm-x86/pgtable.h~x86-implement-pte_special include/asm-x86/pgtable.h --- a/include/asm-x86/pgtable.h~x86-implement-pte_special +++ a/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 */ @@ -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) @@ -194,7 +197,7 @@ 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) @@ -260,7 +263,7 @@ 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; _