x86/mm/pkeys: Add arch-specific VMA protection bits

[cascardo/linux.git] / arch / x86 / include / asm / pgtable_types.h

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index cae10ba..8c35cf0 100644 (file)
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -115,7 +115,12 @@
 #define _KERNPG_TABLE  (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED |    \
                         _PAGE_DIRTY)
 
-/* Set of bits not changed in pte_modify */
+/*
+ * Set of bits not changed in pte_modify.  The pte's
+ * protection key is treated like _PAGE_RW, for
+ * instance, and is *not* included in this mask since
+ * pte_modify() does modify it.
+ */
 #define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |         \
                         _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY | \
                         _PAGE_SOFT_DIRTY)
@@ -231,7 +236,10 @@ enum page_cache_mode {
 /* Extracts the PFN from a (pte|pmd|pud|pgd)val_t of a 4KB page */
 #define PTE_PFN_MASK           ((pteval_t)PHYSICAL_PAGE_MASK)
 
-/* Extracts the flags from a (pte|pmd|pud|pgd)val_t of a 4KB page */
+/*
+ *  Extracts the flags from a (pte|pmd|pud|pgd)val_t
+ *  This includes the protection key value.
+ */
 #define PTE_FLAGS_MASK         (~PTE_PFN_MASK)
 
 typedef struct pgprot { pgprotval_t pgprot; } pgprot_t;