[PATCH] x86_64: support for file offsets in pte's

Path from Andi Kleen <ak@muc.de>

Add x86_64 support for file offsets in pte's.

include/asm-x86_64/page.h

@@ -69,8 +69,9 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 /* See Documentation/x86_64/mm.txt for a description of the memory map. */
 #define __START_KERNEL		0xffffffff80100000
 #define __START_KERNEL_map	0xffffffff80000000
-#define __PAGE_OFFSET           0x0000010000000000
-#define __PHYSICAL_MASK		0x000000ffffffffff
+#define __PAGE_OFFSET           0x0000010000000000	/* 1 << 40 */
+#define __PHYSICAL_MASK_SHIFT	40
+#define __PHYSICAL_MASK		((1UL << __PHYSICAL_MASK_SHIFT) - 1)
 
 #define KERNEL_TEXT_SIZE  (40UL*1024*1024)
 #define KERNEL_TEXT_START 0xffffffff80000000UL 

include/asm-x86_64/pgtable.h

@@ -151,6 +151,7 @@ static inline void set_pml4(pml4_t *dst, pml4_t val)
 #define _PAGE_ACCESSED	0x020
 #define _PAGE_DIRTY	0x040
 #define _PAGE_PSE	0x080	/* 2MB page */
+#define _PAGE_FILE	0x040	/* pagecache or swap */
 #define _PAGE_GLOBAL	0x100	/* Global TLB entry */
 
 #define _PAGE_PROTNONE	0x080	/* If not present */
@@ -245,6 +246,7 @@ extern inline int pte_exec(pte_t pte)		{ return pte_val(pte) & _PAGE_USER; }
 extern inline int pte_dirty(pte_t pte)		{ return pte_val(pte) & _PAGE_DIRTY; }
 extern inline int pte_young(pte_t pte)		{ return pte_val(pte) & _PAGE_ACCESSED; }
 extern inline int pte_write(pte_t pte)		{ return pte_val(pte) & _PAGE_RW; }
+static inline int pte_file(pte_t pte)		{ return pte_val(pte) & _PAGE_FILE; }
 
 extern inline pte_t pte_rdprotect(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_USER)); return pte; }
 extern inline pte_t pte_exprotect(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_USER)); return pte; }
@@ -330,6 +332,11 @@ static inline pgd_t *current_pgd_offset_k(unsigned long address)
 #define	pmd_bad(x)	((pmd_val(x) & (~PTE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE )
 #define pfn_pmd(nr,prot) (__pmd(((nr) << PAGE_SHIFT) | pgprot_val(prot)))
 
+
+#define pte_to_pgoff(pte) ((pte_val(pte) & PHYSICAL_PAGE_MASK) >> PAGE_SHIFT)
+#define pgoff_to_pte(off) ((pte_t) { ((off) << PAGE_SHIFT) | _PAGE_FILE })
+#define PTE_FILE_MAX_BITS __PHYSICAL_MASK_SHIFT
+
 /* PTE - Level 1 access. */
 
 /* page, protection -> pte */