#ifndef _X86_64_PGTABLE_H
  #define _X86_64_PGTABLE_H

  #include <linux/const.h>

  #ifndef __ASSEMBLY__

  /*
   * This file contains the functions and defines necessary to modify and use
   * the x86-64 page table tree.
   */
  #include <asm/processor.h>

  #include <asm/bitops.h>
  #include <linux/threads.h>
  #include <asm/pda.h>
  
  extern pud_t level3_kernel_pgt[512];

  extern pud_t level3_ident_pgt[512];
  extern pmd_t level2_kernel_pgt[512];
  extern pgd_t init_level4_pgt[];
  extern unsigned long __supported_pte_mask;

  #define swapper_pg_dir init_level4_pgt

  extern void paging_init(void);
  extern void clear_kernel_mapping(unsigned long addr, unsigned long size);

  /*
   * ZERO_PAGE is a global shared page that is always zero: used
   * for zero-mapped memory areas etc..
   */
  extern unsigned long empty_zero_page[PAGE_SIZE/sizeof(unsigned long)];

  #define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))

  #endif /* !__ASSEMBLY__ */

  /*
   * PGDIR_SHIFT determines what a top-level page table entry can map
   */
  #define PGDIR_SHIFT	39
  #define PTRS_PER_PGD	512
  
  /*
   * 3rd level page
   */
  #define PUD_SHIFT	30
  #define PTRS_PER_PUD	512
  
  /*
   * PMD_SHIFT determines the size of the area a middle-level
   * page table can map
   */
  #define PMD_SHIFT	21
  #define PTRS_PER_PMD	512
  
  /*
   * entries per page directory level
   */
  #define PTRS_PER_PTE	512

  #ifndef __ASSEMBLY__

  #define pte_ERROR(e) \
  	printk("%s:%d: bad pte %p(%016lx).
  ", __FILE__, __LINE__, &(e), pte_val(e))
  #define pmd_ERROR(e) \
  	printk("%s:%d: bad pmd %p(%016lx).
  ", __FILE__, __LINE__, &(e), pmd_val(e))
  #define pud_ERROR(e) \
  	printk("%s:%d: bad pud %p(%016lx).
  ", __FILE__, __LINE__, &(e), pud_val(e))
  #define pgd_ERROR(e) \
  	printk("%s:%d: bad pgd %p(%016lx).
  ", __FILE__, __LINE__, &(e), pgd_val(e))
  
  #define pgd_none(x)	(!pgd_val(x))
  #define pud_none(x)	(!pud_val(x))
  
  static inline void set_pte(pte_t *dst, pte_t val)
  {
  	pte_val(*dst) = pte_val(val);
  } 
  #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
  
  static inline void set_pmd(pmd_t *dst, pmd_t val)
  {
          pmd_val(*dst) = pmd_val(val); 
  } 
  
  static inline void set_pud(pud_t *dst, pud_t val)
  {
  	pud_val(*dst) = pud_val(val);
  }

  static inline void pud_clear (pud_t *pud)

  {
  	set_pud(pud, __pud(0));
  }
  
  static inline void set_pgd(pgd_t *dst, pgd_t val)
  {
  	pgd_val(*dst) = pgd_val(val); 
  } 

  static inline void pgd_clear (pgd_t * pgd)

  {
  	set_pgd(pgd, __pgd(0));
  }

  #define ptep_get_and_clear(mm,addr,xp)	__pte(xchg(&(xp)->pte, 0))

  struct mm_struct;

  static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, unsigned long addr, pte_t *ptep, int full)
  {
  	pte_t pte;
  	if (full) {
  		pte = *ptep;
  		*ptep = __pte(0);
  	} else {
  		pte = ptep_get_and_clear(mm, addr, ptep);
  	}
  	return pte;
  }

  #define pte_same(a, b)		((a).pte == (b).pte)

  #define pte_pgprot(a)	(__pgprot((a).pte & ~PHYSICAL_PAGE_MASK))

  #endif /* !__ASSEMBLY__ */
  
  #define PMD_SIZE	(_AC(1,UL) << PMD_SHIFT)

  #define PMD_MASK	(~(PMD_SIZE-1))

  #define PUD_SIZE	(_AC(1,UL) << PUD_SHIFT)

  #define PUD_MASK	(~(PUD_SIZE-1))

  #define PGDIR_SIZE	(_AC(1,UL) << PGDIR_SHIFT)

  #define PGDIR_MASK	(~(PGDIR_SIZE-1))

  #define USER_PTRS_PER_PGD	((TASK_SIZE-1)/PGDIR_SIZE+1)

  #define FIRST_USER_ADDRESS	0

  #define MAXMEM		 _AC(0x3fffffffffff, UL)
  #define VMALLOC_START    _AC(0xffffc20000000000, UL)
  #define VMALLOC_END      _AC(0xffffe1ffffffffff, UL)
  #define MODULES_VADDR    _AC(0xffffffff88000000, UL)
  #define MODULES_END      _AC(0xfffffffffff00000, UL)

  #define MODULES_LEN   (MODULES_END - MODULES_VADDR)
  
  #define _PAGE_BIT_PRESENT	0
  #define _PAGE_BIT_RW		1
  #define _PAGE_BIT_USER		2
  #define _PAGE_BIT_PWT		3
  #define _PAGE_BIT_PCD		4
  #define _PAGE_BIT_ACCESSED	5
  #define _PAGE_BIT_DIRTY		6
  #define _PAGE_BIT_PSE		7	/* 4 MB (or 2MB) page */
  #define _PAGE_BIT_GLOBAL	8	/* Global TLB entry PPro+ */
  #define _PAGE_BIT_NX           63       /* No execute: only valid after cpuid check */
  
  #define _PAGE_PRESENT	0x001
  #define _PAGE_RW	0x002
  #define _PAGE_USER	0x004
  #define _PAGE_PWT	0x008
  #define _PAGE_PCD	0x010
  #define _PAGE_ACCESSED	0x020
  #define _PAGE_DIRTY	0x040
  #define _PAGE_PSE	0x080	/* 2MB page */

  #define _PAGE_FILE	0x040	/* nonlinear file mapping, saved PTE; unset:swap */

  #define _PAGE_GLOBAL	0x100	/* Global TLB entry */
  
  #define _PAGE_PROTNONE	0x080	/* If not present */

  #define _PAGE_NX        (_AC(1,UL)<<_PAGE_BIT_NX)

  
  #define _PAGE_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_DIRTY)
  #define _KERNPG_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
  
  #define _PAGE_CHG_MASK	(PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
  
  #define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
  #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_NX)
  #define PAGE_SHARED_EXEC __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED)
  #define PAGE_COPY_NOEXEC __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_NX)
  #define PAGE_COPY PAGE_COPY_NOEXEC
  #define PAGE_COPY_EXEC __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
  #define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_NX)
  #define PAGE_READONLY_EXEC __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
  #define __PAGE_KERNEL \
  	(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_NX)
  #define __PAGE_KERNEL_EXEC \
  	(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
  #define __PAGE_KERNEL_NOCACHE \
  	(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_PCD | _PAGE_ACCESSED | _PAGE_NX)
  #define __PAGE_KERNEL_RO \
  	(_PAGE_PRESENT | _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_NX)
  #define __PAGE_KERNEL_VSYSCALL \
  	(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
  #define __PAGE_KERNEL_VSYSCALL_NOCACHE \
  	(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_PCD)
  #define __PAGE_KERNEL_LARGE \
  	(__PAGE_KERNEL | _PAGE_PSE)

  #define __PAGE_KERNEL_LARGE_EXEC \
  	(__PAGE_KERNEL_EXEC | _PAGE_PSE)

  
  #define MAKE_GLOBAL(x) __pgprot((x) | _PAGE_GLOBAL)
  
  #define PAGE_KERNEL MAKE_GLOBAL(__PAGE_KERNEL)
  #define PAGE_KERNEL_EXEC MAKE_GLOBAL(__PAGE_KERNEL_EXEC)
  #define PAGE_KERNEL_RO MAKE_GLOBAL(__PAGE_KERNEL_RO)
  #define PAGE_KERNEL_NOCACHE MAKE_GLOBAL(__PAGE_KERNEL_NOCACHE)
  #define PAGE_KERNEL_VSYSCALL32 __pgprot(__PAGE_KERNEL_VSYSCALL)
  #define PAGE_KERNEL_VSYSCALL MAKE_GLOBAL(__PAGE_KERNEL_VSYSCALL)
  #define PAGE_KERNEL_LARGE MAKE_GLOBAL(__PAGE_KERNEL_LARGE)
  #define PAGE_KERNEL_VSYSCALL_NOCACHE MAKE_GLOBAL(__PAGE_KERNEL_VSYSCALL_NOCACHE)
  
  /*         xwr */
  #define __P000	PAGE_NONE
  #define __P001	PAGE_READONLY
  #define __P010	PAGE_COPY
  #define __P011	PAGE_COPY
  #define __P100	PAGE_READONLY_EXEC
  #define __P101	PAGE_READONLY_EXEC
  #define __P110	PAGE_COPY_EXEC
  #define __P111	PAGE_COPY_EXEC
  
  #define __S000	PAGE_NONE
  #define __S001	PAGE_READONLY
  #define __S010	PAGE_SHARED
  #define __S011	PAGE_SHARED
  #define __S100	PAGE_READONLY_EXEC
  #define __S101	PAGE_READONLY_EXEC
  #define __S110	PAGE_SHARED_EXEC
  #define __S111	PAGE_SHARED_EXEC

  #ifndef __ASSEMBLY__

  static inline unsigned long pgd_bad(pgd_t pgd)
  {
  	return pgd_val(pgd) & ~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER);
  }

  
  static inline unsigned long pud_bad(pud_t pud)
  {

  	return pud_val(pud) & ~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER);
  }
  
  static inline unsigned long pmd_bad(pmd_t pmd)
  {
  	return pmd_val(pmd) & ~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER);

  }
  
  #define pte_none(x)	(!pte_val(x))
  #define pte_present(x)	(pte_val(x) & (_PAGE_PRESENT | _PAGE_PROTNONE))
  #define pte_clear(mm,addr,xp)	do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)
  
  #define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT))	/* FIXME: is this
  						   right? */
  #define pte_page(x)	pfn_to_page(pte_pfn(x))

  #define pte_pfn(x)  ((pte_val(x) & __PHYSICAL_MASK) >> PAGE_SHIFT)

  
  static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
  {
  	pte_t pte;
  	pte_val(pte) = (page_nr << PAGE_SHIFT);
  	pte_val(pte) |= pgprot_val(pgprot);
  	pte_val(pte) &= __supported_pte_mask;
  	return pte;
  }
  
  /*
   * The following only work if pte_present() is true.
   * Undefined behaviour if not..
   */

  #define __LARGE_PTE (_PAGE_PSE|_PAGE_PRESENT)

  static inline int pte_dirty(pte_t pte)		{ return pte_val(pte) & _PAGE_DIRTY; }
  static inline int pte_young(pte_t pte)		{ return pte_val(pte) & _PAGE_ACCESSED; }
  static 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; }

  static inline int pte_huge(pte_t pte)		{ return pte_val(pte) & _PAGE_PSE; }

  static inline pte_t pte_mkclean(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_DIRTY)); return pte; }
  static inline pte_t pte_mkold(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_ACCESSED)); return pte; }
  static inline pte_t pte_wrprotect(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_RW)); return pte; }

  static inline pte_t pte_mkexec(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_NX)); return pte; }

  static inline pte_t pte_mkdirty(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | _PAGE_DIRTY)); return pte; }
  static inline pte_t pte_mkyoung(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | _PAGE_ACCESSED)); return pte; }
  static inline pte_t pte_mkwrite(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | _PAGE_RW)); return pte; }

  static inline pte_t pte_mkhuge(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) | _PAGE_PSE)); return pte; }

  static inline pte_t pte_clrhuge(pte_t pte)	{ set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_PSE)); return pte; }

  
  struct vm_area_struct;

  static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
  {
  	if (!pte_young(*ptep))
  		return 0;

  	return test_and_clear_bit(_PAGE_BIT_ACCESSED, &ptep->pte);

  }
  
  static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
  {

  	clear_bit(_PAGE_BIT_RW, &ptep->pte);

  }
  
  /*
   * Macro to mark a page protection value as "uncacheable".
   */
  #define pgprot_noncached(prot)	(__pgprot(pgprot_val(prot) | _PAGE_PCD | _PAGE_PWT))

  static inline int pmd_large(pmd_t pte) { 
  	return (pmd_val(pte) & __LARGE_PTE) == __LARGE_PTE; 
  } 	
  
  
  /*
   * Conversion functions: convert a page and protection to a page entry,
   * and a page entry and page directory to the page they refer to.
   */

  /*
   * Level 4 access.
   */

  #define pgd_page_vaddr(pgd) ((unsigned long) __va((unsigned long)pgd_val(pgd) & PTE_MASK))
  #define pgd_page(pgd)		(pfn_to_page(pgd_val(pgd) >> PAGE_SHIFT))

  #define pgd_index(address) (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
  #define pgd_offset(mm, addr) ((mm)->pgd + pgd_index(addr))
  #define pgd_offset_k(address) (init_level4_pgt + pgd_index(address))
  #define pgd_present(pgd) (pgd_val(pgd) & _PAGE_PRESENT)
  #define mk_kernel_pgd(address) ((pgd_t){ (address) | _KERNPG_TABLE })
  
  /* PUD - Level3 access */
  /* to find an entry in a page-table-directory. */

  #define pud_page_vaddr(pud) ((unsigned long) __va(pud_val(pud) & PHYSICAL_PAGE_MASK))
  #define pud_page(pud)		(pfn_to_page(pud_val(pud) >> PAGE_SHIFT))

  #define pud_index(address) (((address) >> PUD_SHIFT) & (PTRS_PER_PUD-1))

  #define pud_offset(pgd, address) ((pud_t *) pgd_page_vaddr(*(pgd)) + pud_index(address))

  #define pud_present(pud) (pud_val(pud) & _PAGE_PRESENT)

  /* PMD  - Level 2 access */

  #define pmd_page_vaddr(pmd) ((unsigned long) __va(pmd_val(pmd) & PTE_MASK))

  #define pmd_page(pmd)		(pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT))
  
  #define pmd_index(address) (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))

  #define pmd_offset(dir, address) ((pmd_t *) pud_page_vaddr(*(dir)) + \

  			pmd_index(address))
  #define pmd_none(x)	(!pmd_val(x))
  #define pmd_present(x)	(pmd_val(x) & _PAGE_PRESENT)
  #define pmd_clear(xp)	do { set_pmd(xp, __pmd(0)); } while (0)

  #define pfn_pmd(nr,prot) (__pmd(((nr) << PAGE_SHIFT) | pgprot_val(prot)))

  #define pmd_pfn(x)  ((pmd_val(x) & __PHYSICAL_MASK) >> PAGE_SHIFT)

  
  #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 */
  #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))
  #define mk_pte_huge(entry) (pte_val(entry) |= _PAGE_PRESENT | _PAGE_PSE)
   

  /* Change flags of a PTE */

  static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)

  { 
  	pte_val(pte) &= _PAGE_CHG_MASK;
  	pte_val(pte) |= pgprot_val(newprot);
  	pte_val(pte) &= __supported_pte_mask;
         return pte; 
  }
  
  #define pte_index(address) \

  		(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))

  #define pte_offset_kernel(dir, address) ((pte_t *) pmd_page_vaddr(*(dir)) + \

  			pte_index(address))
  
  /* x86-64 always has all page tables mapped. */
  #define pte_offset_map(dir,address) pte_offset_kernel(dir,address)
  #define pte_offset_map_nested(dir,address) pte_offset_kernel(dir,address)
  #define pte_unmap(pte) /* NOP */
  #define pte_unmap_nested(pte) /* NOP */ 
  
  #define update_mmu_cache(vma,address,pte) do { } while (0)
  
  /* We only update the dirty/accessed state if we set
   * the dirty bit by hand in the kernel, since the hardware
   * will do the accessed bit for us, and we don't want to
   * race with other CPU's that might be updating the dirty
   * bit at the same time. */
  #define  __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
  #define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \

  ({									  \
  	int __changed = !pte_same(*(__ptep), __entry);			  \
  	if (__changed && __dirty) {					  \
  		set_pte(__ptep, __entry);			  	  \
  		flush_tlb_page(__vma, __address);		  	  \
  	}								  \
  	__changed;							  \
  })

  
  /* Encode and de-code a swap entry */
  #define __swp_type(x)			(((x).val >> 1) & 0x3f)
  #define __swp_offset(x)			((x).val >> 8)
  #define __swp_entry(type, offset)	((swp_entry_t) { ((type) << 1) | ((offset) << 8) })
  #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) })
  #define __swp_entry_to_pte(x)		((pte_t) { (x).val })

  extern spinlock_t pgd_lock;

  extern struct list_head pgd_list;

  extern int kern_addr_valid(unsigned long addr); 

  pte_t *lookup_address(unsigned long addr);

  #define io_remap_pfn_range(vma, vaddr, pfn, size, prot)		\
  		remap_pfn_range(vma, vaddr, pfn, size, prot)

  #define HAVE_ARCH_UNMAPPED_AREA
  
  #define pgtable_cache_init()   do { } while (0)

  
  #define PAGE_AGP    PAGE_KERNEL_NOCACHE
  #define HAVE_PAGE_AGP 1
  
  /* fs/proc/kcore.c */
  #define	kc_vaddr_to_offset(v) ((v) & __VIRTUAL_MASK)
  #define	kc_offset_to_vaddr(o) \
     (((o) & (1UL << (__VIRTUAL_MASK_SHIFT-1))) ? ((o) | (~__VIRTUAL_MASK)) : (o))
  
  #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG

  #define __HAVE_ARCH_PTEP_GET_AND_CLEAR

  #define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL

  #define __HAVE_ARCH_PTEP_SET_WRPROTECT
  #define __HAVE_ARCH_PTE_SAME
  #include <asm-generic/pgtable.h>

  #endif /* !__ASSEMBLY__ */

  
  #endif /* _X86_64_PGTABLE_H */