#ifndef _ASM_GENERIC_PGTABLE_H
  #define _ASM_GENERIC_PGTABLE_H

  #ifndef __ASSEMBLY__

  #ifdef CONFIG_MMU

  #include <linux/mm_types.h>

  #ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS

  extern int ptep_set_access_flags(struct vm_area_struct *vma,
  				 unsigned long address, pte_t *ptep,
  				 pte_t entry, int dirty);
  #endif
  
  #ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
  extern int pmdp_set_access_flags(struct vm_area_struct *vma,
  				 unsigned long address, pmd_t *pmdp,
  				 pmd_t entry, int dirty);

  #endif
  
  #ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG

  static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
  					    unsigned long address,
  					    pte_t *ptep)
  {
  	pte_t pte = *ptep;
  	int r = 1;
  	if (!pte_young(pte))
  		r = 0;
  	else
  		set_pte_at(vma->vm_mm, address, ptep, pte_mkold(pte));
  	return r;
  }
  #endif
  
  #ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
  					    unsigned long address,
  					    pmd_t *pmdp)
  {
  	pmd_t pmd = *pmdp;
  	int r = 1;
  	if (!pmd_young(pmd))
  		r = 0;
  	else
  		set_pmd_at(vma->vm_mm, address, pmdp, pmd_mkold(pmd));
  	return r;
  }
  #else /* CONFIG_TRANSPARENT_HUGEPAGE */
  static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
  					    unsigned long address,
  					    pmd_t *pmdp)
  {
  	BUG();
  	return 0;
  }
  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */

  #endif
  
  #ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH

  int ptep_clear_flush_young(struct vm_area_struct *vma,
  			   unsigned long address, pte_t *ptep);
  #endif
  
  #ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
  int pmdp_clear_flush_young(struct vm_area_struct *vma,
  			   unsigned long address, pmd_t *pmdp);

  #endif

  #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR

  static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
  				       unsigned long address,
  				       pte_t *ptep)
  {
  	pte_t pte = *ptep;
  	pte_clear(mm, address, ptep);
  	return pte;
  }
  #endif
  
  #ifndef __HAVE_ARCH_PMDP_GET_AND_CLEAR
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm,
  				       unsigned long address,
  				       pmd_t *pmdp)
  {
  	pmd_t pmd = *pmdp;
  	pmd_clear(mm, address, pmdp);
  	return pmd;

  }

  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */

  #endif

  #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL

  static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
  					    unsigned long address, pte_t *ptep,
  					    int full)
  {
  	pte_t pte;
  	pte = ptep_get_and_clear(mm, address, ptep);
  	return pte;
  }

  #endif

  /*
   * Some architectures may be able to avoid expensive synchronization
   * primitives when modifications are made to PTE's which are already
   * not present, or in the process of an address space destruction.
   */
  #ifndef __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL

  static inline void pte_clear_not_present_full(struct mm_struct *mm,
  					      unsigned long address,
  					      pte_t *ptep,
  					      int full)
  {
  	pte_clear(mm, address, ptep);
  }

  #endif

  #ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH

  extern pte_t ptep_clear_flush(struct vm_area_struct *vma,
  			      unsigned long address,
  			      pte_t *ptep);
  #endif
  
  #ifndef __HAVE_ARCH_PMDP_CLEAR_FLUSH
  extern pmd_t pmdp_clear_flush(struct vm_area_struct *vma,
  			      unsigned long address,
  			      pmd_t *pmdp);

  #endif
  
  #ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT

  struct mm_struct;

  static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
  {
  	pte_t old_pte = *ptep;
  	set_pte_at(mm, address, ptep, pte_wrprotect(old_pte));
  }
  #endif

  #ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  static inline void pmdp_set_wrprotect(struct mm_struct *mm,
  				      unsigned long address, pmd_t *pmdp)
  {
  	pmd_t old_pmd = *pmdp;
  	set_pmd_at(mm, address, pmdp, pmd_wrprotect(old_pmd));
  }
  #else /* CONFIG_TRANSPARENT_HUGEPAGE */
  static inline void pmdp_set_wrprotect(struct mm_struct *mm,
  				      unsigned long address, pmd_t *pmdp)
  {
  	BUG();
  }
  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
  #endif
  
  #ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH

  extern pmd_t pmdp_splitting_flush(struct vm_area_struct *vma,
  				  unsigned long address,
  				  pmd_t *pmdp);

  #endif

  #ifndef __HAVE_ARCH_PTE_SAME

  static inline int pte_same(pte_t pte_a, pte_t pte_b)
  {
  	return pte_val(pte_a) == pte_val(pte_b);
  }
  #endif
  
  #ifndef __HAVE_ARCH_PMD_SAME
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
  {
  	return pmd_val(pmd_a) == pmd_val(pmd_b);
  }
  #else /* CONFIG_TRANSPARENT_HUGEPAGE */
  static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
  {
  	BUG();
  	return 0;
  }
  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */

  #endif

  #ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY
  #define page_test_and_clear_dirty(pfn, mapped)	(0)

  #endif

  #ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY

  #define pte_maybe_dirty(pte)		pte_dirty(pte)
  #else
  #define pte_maybe_dirty(pte)		(1)

  #endif
  
  #ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG

  #define page_test_and_clear_young(pfn) (0)

  #endif
  
  #ifndef __HAVE_ARCH_PGD_OFFSET_GATE
  #define pgd_offset_gate(mm, addr)	pgd_offset(mm, addr)
  #endif

  #ifndef __HAVE_ARCH_MOVE_PTE

  #define move_pte(pte, prot, old_addr, new_addr)	(pte)

  #endif

  #ifndef flush_tlb_fix_spurious_fault
  #define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address)
  #endif

  #ifndef pgprot_noncached
  #define pgprot_noncached(prot)	(prot)
  #endif

  #ifndef pgprot_writecombine
  #define pgprot_writecombine pgprot_noncached
  #endif

  /*

   * When walking page tables, get the address of the next boundary,
   * or the end address of the range if that comes earlier.  Although no
   * vma end wraps to 0, rounded up __boundary may wrap to 0 throughout.

   */

  #define pgd_addr_end(addr, end)						\
  ({	unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK;	\
  	(__boundary - 1 < (end) - 1)? __boundary: (end);		\
  })

  
  #ifndef pud_addr_end
  #define pud_addr_end(addr, end)						\
  ({	unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK;	\
  	(__boundary - 1 < (end) - 1)? __boundary: (end);		\
  })
  #endif
  
  #ifndef pmd_addr_end
  #define pmd_addr_end(addr, end)						\
  ({	unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK;	\
  	(__boundary - 1 < (end) - 1)? __boundary: (end);		\
  })
  #endif

  /*
   * When walking page tables, we usually want to skip any p?d_none entries;
   * and any p?d_bad entries - reporting the error before resetting to none.
   * Do the tests inline, but report and clear the bad entry in mm/memory.c.
   */
  void pgd_clear_bad(pgd_t *);
  void pud_clear_bad(pud_t *);
  void pmd_clear_bad(pmd_t *);
  
  static inline int pgd_none_or_clear_bad(pgd_t *pgd)
  {
  	if (pgd_none(*pgd))
  		return 1;
  	if (unlikely(pgd_bad(*pgd))) {
  		pgd_clear_bad(pgd);
  		return 1;
  	}
  	return 0;
  }
  
  static inline int pud_none_or_clear_bad(pud_t *pud)
  {
  	if (pud_none(*pud))
  		return 1;
  	if (unlikely(pud_bad(*pud))) {
  		pud_clear_bad(pud);
  		return 1;
  	}
  	return 0;
  }
  
  static inline int pmd_none_or_clear_bad(pmd_t *pmd)
  {
  	if (pmd_none(*pmd))
  		return 1;
  	if (unlikely(pmd_bad(*pmd))) {
  		pmd_clear_bad(pmd);
  		return 1;
  	}
  	return 0;
  }

  static inline pte_t __ptep_modify_prot_start(struct mm_struct *mm,
  					     unsigned long addr,
  					     pte_t *ptep)
  {
  	/*
  	 * Get the current pte state, but zero it out to make it
  	 * non-present, preventing the hardware from asynchronously
  	 * updating it.
  	 */
  	return ptep_get_and_clear(mm, addr, ptep);
  }
  
  static inline void __ptep_modify_prot_commit(struct mm_struct *mm,
  					     unsigned long addr,
  					     pte_t *ptep, pte_t pte)
  {
  	/*
  	 * The pte is non-present, so there's no hardware state to
  	 * preserve.
  	 */
  	set_pte_at(mm, addr, ptep, pte);
  }
  
  #ifndef __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
  /*
   * Start a pte protection read-modify-write transaction, which
   * protects against asynchronous hardware modifications to the pte.
   * The intention is not to prevent the hardware from making pte
   * updates, but to prevent any updates it may make from being lost.
   *
   * This does not protect against other software modifications of the
   * pte; the appropriate pte lock must be held over the transation.
   *
   * Note that this interface is intended to be batchable, meaning that
   * ptep_modify_prot_commit may not actually update the pte, but merely
   * queue the update to be done at some later time.  The update must be
   * actually committed before the pte lock is released, however.
   */
  static inline pte_t ptep_modify_prot_start(struct mm_struct *mm,
  					   unsigned long addr,
  					   pte_t *ptep)
  {
  	return __ptep_modify_prot_start(mm, addr, ptep);
  }
  
  /*
   * Commit an update to a pte, leaving any hardware-controlled bits in
   * the PTE unmodified.
   */
  static inline void ptep_modify_prot_commit(struct mm_struct *mm,
  					   unsigned long addr,
  					   pte_t *ptep, pte_t pte)
  {
  	__ptep_modify_prot_commit(mm, addr, ptep, pte);
  }
  #endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */

  #endif /* CONFIG_MMU */

  /*
   * A facility to provide lazy MMU batching.  This allows PTE updates and
   * page invalidations to be delayed until a call to leave lazy MMU mode
   * is issued.  Some architectures may benefit from doing this, and it is
   * beneficial for both shadow and direct mode hypervisors, which may batch
   * the PTE updates which happen during this window.  Note that using this
   * interface requires that read hazards be removed from the code.  A read
   * hazard could result in the direct mode hypervisor case, since the actual
   * write to the page tables may not yet have taken place, so reads though
   * a raw PTE pointer after it has been modified are not guaranteed to be
   * up to date.  This mode can only be entered and left under the protection of
   * the page table locks for all page tables which may be modified.  In the UP
   * case, this is required so that preemption is disabled, and in the SMP case,
   * it must synchronize the delayed page table writes properly on other CPUs.
   */
  #ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
  #define arch_enter_lazy_mmu_mode()	do {} while (0)
  #define arch_leave_lazy_mmu_mode()	do {} while (0)
  #define arch_flush_lazy_mmu_mode()	do {} while (0)
  #endif
  
  /*

   * A facility to provide batching of the reload of page tables and
   * other process state with the actual context switch code for
   * paravirtualized guests.  By convention, only one of the batched
   * update (lazy) modes (CPU, MMU) should be active at any given time,
   * entry should never be nested, and entry and exits should always be
   * paired.  This is for sanity of maintaining and reasoning about the
   * kernel code.  In this case, the exit (end of the context switch) is
   * in architecture-specific code, and so doesn't need a generic
   * definition.

   */

  #ifndef __HAVE_ARCH_START_CONTEXT_SWITCH

  #define arch_start_context_switch(prev)	do {} while (0)

  #endif

  #ifndef __HAVE_PFNMAP_TRACKING
  /*
   * Interface that can be used by architecture code to keep track of
   * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
   *
   * track_pfn_vma_new is called when a _new_ pfn mapping is being established
   * for physical range indicated by pfn and size.
   */

  static inline int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,

  					unsigned long pfn, unsigned long size)
  {
  	return 0;
  }
  
  /*
   * Interface that can be used by architecture code to keep track of
   * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
   *
   * track_pfn_vma_copy is called when vma that is covering the pfnmap gets
   * copied through copy_page_range().
   */
  static inline int track_pfn_vma_copy(struct vm_area_struct *vma)
  {
  	return 0;
  }
  
  /*
   * Interface that can be used by architecture code to keep track of
   * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
   *
   * untrack_pfn_vma is called while unmapping a pfnmap for a region.
   * untrack can be called for a specific region indicated by pfn and size or
   * can be for the entire vma (in which case size can be zero).
   */
  static inline void untrack_pfn_vma(struct vm_area_struct *vma,
  					unsigned long pfn, unsigned long size)
  {
  }
  #else

  extern int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,

  				unsigned long pfn, unsigned long size);
  extern int track_pfn_vma_copy(struct vm_area_struct *vma);
  extern void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
  				unsigned long size);
  #endif

  #ifndef CONFIG_TRANSPARENT_HUGEPAGE
  static inline int pmd_trans_huge(pmd_t pmd)
  {
  	return 0;
  }
  static inline int pmd_trans_splitting(pmd_t pmd)
  {
  	return 0;
  }

  #ifndef __HAVE_ARCH_PMD_WRITE
  static inline int pmd_write(pmd_t pmd)
  {
  	BUG();
  	return 0;
  }
  #endif /* __HAVE_ARCH_PMD_WRITE */

  #endif

  #endif /* !__ASSEMBLY__ */
  
  #endif /* _ASM_GENERIC_PGTABLE_H */