Previous documentation has referred to these 4 bits as "ignored". That means that software could have made use of them. But, as far as I know, the kernel never used them. They are still ignored when protection keys is not enabled, so they could theoretically still get used for software purposes. We also implement "empty" versions so that code that references to them can be optimized away by the compiler when the config option is not enabled. --- b/arch/x86/include/asm/pgtable_types.h | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff -puN arch/x86/include/asm/pgtable_types.h~pkeys-04-ptebits arch/x86/include/asm/pgtable_types.h --- a/arch/x86/include/asm/pgtable_types.h~pkeys-04-ptebits 2015-09-16 10:48:13.805081207 -0700 +++ b/arch/x86/include/asm/pgtable_types.h 2015-09-16 10:48:13.809081388 -0700 @@ -25,7 +25,11 @@ #define _PAGE_BIT_SPLITTING _PAGE_BIT_SOFTW2 /* only valid on a PSE pmd */ #define _PAGE_BIT_HIDDEN _PAGE_BIT_SOFTW3 /* hidden by kmemcheck */ #define _PAGE_BIT_SOFT_DIRTY _PAGE_BIT_SOFTW3 /* software dirty tracking */ -#define _PAGE_BIT_NX 63 /* No execute: only valid after cpuid check */ +#define _PAGE_BIT_PKEY_BIT0 59 /* Protection Keys, bit 1/4 */ +#define _PAGE_BIT_PKEY_BIT1 60 /* Protection Keys, bit 2/4 */ +#define _PAGE_BIT_PKEY_BIT2 61 /* Protection Keys, bit 3/4 */ +#define _PAGE_BIT_PKEY_BIT3 62 /* Protection Keys, bit 4/4 */ +#define _PAGE_BIT_NX 63 /* No execute: only valid after cpuid check */ /* If _PAGE_BIT_PRESENT is clear, we use these: */ /* - if the user mapped it with PROT_NONE; pte_present gives true */ @@ -47,6 +51,17 @@ #define _PAGE_SPECIAL (_AT(pteval_t, 1) << _PAGE_BIT_SPECIAL) #define _PAGE_CPA_TEST (_AT(pteval_t, 1) << _PAGE_BIT_CPA_TEST) #define _PAGE_SPLITTING (_AT(pteval_t, 1) << _PAGE_BIT_SPLITTING) +#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS +#define _PAGE_PKEY_BIT0 (_AT(pteval_t, 1) << _PAGE_BIT_PKEY_BIT0) +#define _PAGE_PKEY_BIT1 (_AT(pteval_t, 1) << _PAGE_BIT_PKEY_BIT1) +#define _PAGE_PKEY_BIT2 (_AT(pteval_t, 1) << _PAGE_BIT_PKEY_BIT2) +#define _PAGE_PKEY_BIT3 (_AT(pteval_t, 1) << _PAGE_BIT_PKEY_BIT3) +#else +#define _PAGE_PKEY_BIT0 (_AT(pteval_t, 0)) +#define _PAGE_PKEY_BIT1 (_AT(pteval_t, 0)) +#define _PAGE_PKEY_BIT2 (_AT(pteval_t, 0)) +#define _PAGE_PKEY_BIT3 (_AT(pteval_t, 0)) +#endif #define __HAVE_ARCH_PTE_SPECIAL #ifdef CONFIG_KMEMCHECK _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>