text: #ifndef _PARISC_PGTABLE_H
  #define _PARISC_PGTABLE_H
  
  #include <linux/config.h>
  #include <asm/fixmap.h>
  
  #ifndef __ASSEMBLY__
  /*
   * we simulate an x86-style page table for the linux mm code
   */
  
  #include <linux/spinlock.h>
  #include <asm/processor.h>
  #include <asm/cache.h>
  #include <asm/bitops.h>
  
  /*
   * kern_addr_valid(ADDR) tests if ADDR is pointing to valid kernel
   * memory.  For the return value to be meaningful, ADDR must be >=
   * PAGE_OFFSET.  This operation can be relatively expensive (e.g.,
   * require a hash-, or multi-level tree-lookup or something of that
   * sort) but it guarantees to return TRUE only if accessing the page
   * at that address does not cause an error.  Note that there may be
   * addresses for which kern_addr_valid() returns FALSE even though an
   * access would not cause an error (e.g., this is typically true for
   * memory mapped I/O regions.
   *
   * XXX Need to implement this for parisc.
   */
  #define kern_addr_valid(addr)	(1)
  
  /* Certain architectures need to do special things when PTEs
   * within a page table are directly modified.  Thus, the following
   * hook is made available.
   */
  #define set_pte(pteptr, pteval)                                 \
          do{                                                     \
                  *(pteptr) = (pteval);                           \
          } while(0)
  
  #endif /* !__ASSEMBLY__ */
  
  #define pte_ERROR(e) \
  	printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
  #define pmd_ERROR(e) \
  	printk("%s:%d: bad pmd %08lx.\n", __FILE__, __LINE__, pmd_val(e))
  #define pgd_ERROR(e) \
  	printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
  
   /* Note: If you change ISTACK_SIZE, you need to change the corresponding
    * values in vmlinux.lds and vmlinux64.lds (init_istack section). Also,
    * the "order" and size need to agree.
    */
  
  #define  ISTACK_SIZE  32768 /* Interrupt Stack Size */
  #define  ISTACK_ORDER 3
  
  /*
   * NOTE: Many of the below macros use PT_NLEVELS because
   *       it is convenient that PT_NLEVELS == LOG2(pte size in bytes),
   *       i.e. we use 3 level page tables when we use 8 byte pte's
   *       (for 64 bit) and 2 level page tables when we use 4 byte pte's
   */
  
  #ifdef __LP64__
  #define PT_NLEVELS 3
  #define PT_INITIAL 4 /* Number of initial page tables */
  #else
  #define PT_NLEVELS 2
  #define PT_INITIAL 2 /* Number of initial page tables */
  #endif
  
  #define MAX_ADDRBITS (PAGE_SHIFT + (PT_NLEVELS)*(PAGE_SHIFT - PT_NLEVELS))
  #define MAX_ADDRESS (1UL << MAX_ADDRBITS)
  
  #define SPACEID_SHIFT (MAX_ADDRBITS - 32)
  
  /* Definitions for 1st level */
  
  #define PGDIR_SHIFT  (PAGE_SHIFT + (PT_NLEVELS - 1)*(PAGE_SHIFT - PT_NLEVELS))
  #define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
  #define PGDIR_MASK	(~(PGDIR_SIZE-1))
  #define PTRS_PER_PGD    (1UL << (PAGE_SHIFT - PT_NLEVELS))
  #define USER_PTRS_PER_PGD       PTRS_PER_PGD
  
  /* Definitions for 2nd level */
  #define pgtable_cache_init()	do { } while (0)
  
  #define PMD_SHIFT       (PAGE_SHIFT + (PAGE_SHIFT - PT_NLEVELS))
  #define PMD_SIZE	(1UL << PMD_SHIFT)
  #define PMD_MASK	(~(PMD_SIZE-1))
  #if PT_NLEVELS == 3
  #define PTRS_PER_PMD    (1UL << (PAGE_SHIFT - PT_NLEVELS))
  #else
  #define PTRS_PER_PMD    1
  #endif
  
  /* Definitions for 3rd level */
  
  #define PTRS_PER_PTE    (1UL << (PAGE_SHIFT - PT_NLEVELS))
  
  /*
   * pgd entries used up by user/kernel:
   */
  
  #define FIRST_USER_PGD_NR	0
  
  #ifndef __ASSEMBLY__
  extern  void *vmalloc_start;
  #define PCXL_DMA_MAP_SIZE   (8*1024*1024)
  #define VMALLOC_START   ((unsigned long)vmalloc_start)
  /* this is a fixmap remnant, see fixmap.h */
  #define VMALLOC_END	(TMPALIAS_MAP_START)
  #endif
  
  /* NB: The tlb miss handlers make certain assumptions about the order */
  /*     of the following bits, so be careful (One example, bits 25-31  */
  /*     are moved together in one instruction).                        */
  
  #define _PAGE_READ_BIT     31   /* (0x001) read access allowed */
  #define _PAGE_WRITE_BIT    30   /* (0x002) write access allowed */
  #define _PAGE_EXEC_BIT     29   /* (0x004) execute access allowed */
  #define _PAGE_GATEWAY_BIT  28   /* (0x008) privilege promotion allowed */
  #define _PAGE_DMB_BIT      27   /* (0x010) Data Memory Break enable (B bit) */
  #define _PAGE_DIRTY_BIT    26   /* (0x020) Page Dirty (D bit) */
  #define _PAGE_FILE_BIT	_PAGE_DIRTY_BIT	/* overload this bit */
  #define _PAGE_REFTRAP_BIT  25   /* (0x040) Page Ref. Trap enable (T bit) */
  #define _PAGE_NO_CACHE_BIT 24   /* (0x080) Uncached Page (U bit) */
  #define _PAGE_ACCESSED_BIT 23   /* (0x100) Software: Page Accessed */
  #define _PAGE_PRESENT_BIT  22   /* (0x200) Software: translation valid */
  #define _PAGE_FLUSH_BIT    21   /* (0x400) Software: translation valid */
  				/*             for cache flushing only */
  #define _PAGE_USER_BIT     20   /* (0x800) Software: User accessible page */
  
  /* N.B. The bits are defined in terms of a 32 bit word above, so the */
  /*      following macro is ok for both 32 and 64 bit.                */
  
  #define xlate_pabit(x) (31 - x)
  
  /* this defines the shift to the usable bits in the PTE it is set so
   * that the valid bits _PAGE_PRESENT_BIT and _PAGE_USER_BIT are set
   * to zero */
  #define PTE_SHIFT	   	xlate_pabit(_PAGE_USER_BIT)
  
  /* this is how many bits may be used by the file functions */
  #define PTE_FILE_MAX_BITS	(BITS_PER_LONG - PTE_SHIFT)
  
  #define pte_to_pgoff(pte) (pte_val(pte) >> PTE_SHIFT)
  #define pgoff_to_pte(off) ((pte_t) { ((off) << PTE_SHIFT) | _PAGE_FILE })
  
  #define _PAGE_READ     (1 << xlate_pabit(_PAGE_READ_BIT))
  #define _PAGE_WRITE    (1 << xlate_pabit(_PAGE_WRITE_BIT))
  #define _PAGE_RW       (_PAGE_READ | _PAGE_WRITE)
  #define _PAGE_EXEC     (1 << xlate_pabit(_PAGE_EXEC_BIT))
  #define _PAGE_GATEWAY  (1 << xlate_pabit(_PAGE_GATEWAY_BIT))
  #define _PAGE_DMB      (1 << xlate_pabit(_PAGE_DMB_BIT))
  #define _PAGE_DIRTY    (1 << xlate_pabit(_PAGE_DIRTY_BIT))
  #define _PAGE_REFTRAP  (1 << xlate_pabit(_PAGE_REFTRAP_BIT))
  #define _PAGE_NO_CACHE (1 << xlate_pabit(_PAGE_NO_CACHE_BIT))
  #define _PAGE_ACCESSED (1 << xlate_pabit(_PAGE_ACCESSED_BIT))
  #define _PAGE_PRESENT  (1 << xlate_pabit(_PAGE_PRESENT_BIT))
  #define _PAGE_FLUSH    (1 << xlate_pabit(_PAGE_FLUSH_BIT))
  #define _PAGE_USER     (1 << xlate_pabit(_PAGE_USER_BIT))
  #define _PAGE_FILE     (1 << xlate_pabit(_PAGE_FILE_BIT))
  
  #define _PAGE_TABLE	(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE |  _PAGE_DIRTY | _PAGE_ACCESSED)
  #define _PAGE_CHG_MASK	(PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
  #define _PAGE_KERNEL	(_PAGE_PRESENT | _PAGE_EXEC | _PAGE_READ | _PAGE_WRITE | _PAGE_DIRTY | _PAGE_ACCESSED)
  
  #ifndef __ASSEMBLY__
  
  #define PAGE_NONE	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
  #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_READ | _PAGE_WRITE | _PAGE_ACCESSED)
  /* Others seem to make this executable, I don't know if that's correct
     or not.  The stack is mapped this way though so this is necessary
     in the short term - dhd@linuxcare.com, 2000-08-08 */
  #define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_READ | _PAGE_ACCESSED)
  #define PAGE_WRITEONLY  __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_WRITE | _PAGE_ACCESSED)
  #define PAGE_EXECREAD   __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_READ | _PAGE_EXEC |_PAGE_ACCESSED)
  #define PAGE_COPY       PAGE_EXECREAD
  #define PAGE_RWX        __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_READ | _PAGE_WRITE | _PAGE_EXEC |_PAGE_ACCESSED)
  #define PAGE_KERNEL	__pgprot(_PAGE_KERNEL)
  #define PAGE_KERNEL_RO	__pgprot(_PAGE_PRESENT | _PAGE_EXEC | _PAGE_READ | _PAGE_DIRTY | _PAGE_ACCESSED)
  #define PAGE_KERNEL_UNC	__pgprot(_PAGE_KERNEL | _PAGE_NO_CACHE)
  #define PAGE_GATEWAY    __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_GATEWAY| _PAGE_READ)
  #define PAGE_FLUSH      __pgprot(_PAGE_FLUSH)
  
  
  /*
   * We could have an execute only page using "gateway - promote to priv
   * level 3", but that is kind of silly. So, the way things are defined
   * now, we must always have read permission for pages with execute
   * permission. For the fun of it we'll go ahead and support write only
   * pages.
   */
  
  	 /*xwr*/
  #define __P000  PAGE_NONE
  #define __P001  PAGE_READONLY
  #define __P010  __P000 /* copy on write */
  #define __P011  __P001 /* copy on write */
  #define __P100  PAGE_EXECREAD
  #define __P101  PAGE_EXECREAD
  #define __P110  __P100 /* copy on write */
  #define __P111  __P101 /* copy on write */
  
  #define __S000  PAGE_NONE
  #define __S001  PAGE_READONLY
  #define __S010  PAGE_WRITEONLY
  #define __S011  PAGE_SHARED
  #define __S100  PAGE_EXECREAD
  #define __S101  PAGE_EXECREAD
  #define __S110  PAGE_RWX
  #define __S111  PAGE_RWX
  
  extern pgd_t swapper_pg_dir[]; /* declared in init_task.c */
  
  /* initial page tables for 0-8MB for kernel */
  
  extern unsigned long pg0[];
  
  /* zero page used for uninitialized stuff */
  
  extern unsigned long *empty_zero_page;
  
  /*
   * ZERO_PAGE is a global shared page that is always zero: used
   * for zero-mapped memory areas etc..
   */
  
  #define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
  
  #define pte_none(x)     ((pte_val(x) == 0) || (pte_val(x) & _PAGE_FLUSH))
  #define pte_present(x)	(pte_val(x) & _PAGE_PRESENT)
  #define pte_clear(xp)	do { pte_val(*(xp)) = 0; } while (0)
  
  #define pmd_none(x)	(!pmd_val(x))
  #define pmd_bad(x)	((pmd_val(x) & ~PAGE_MASK) != _PAGE_TABLE)
  #define pmd_present(x)	(pmd_val(x) & _PAGE_PRESENT)
  #define pmd_clear(xp)	do { pmd_val(*(xp)) = 0; } while (0)
  
  
  
  #ifdef __LP64__
  #define pgd_page(pgd) ((unsigned long) __va(pgd_val(pgd) & PAGE_MASK))
  
  /* For 64 bit we have three level tables */
  
  #define pgd_none(x)     (!pgd_val(x))
  #define pgd_bad(x)      ((pgd_val(x) & ~PAGE_MASK) != _PAGE_TABLE)
  #define pgd_present(x)  (pgd_val(x) & _PAGE_PRESENT)
  #define pgd_clear(xp)   do { pgd_val(*(xp)) = 0; } while (0)
  #else
  /*
   * The "pgd_xxx()" functions here are trivial for a folded two-level
   * setup: the pgd is never bad, and a pmd always exists (as it's folded
   * into the pgd entry)
   */
  extern inline int pgd_none(pgd_t pgd)		{ return 0; }
  extern inline int pgd_bad(pgd_t pgd)		{ return 0; }
  extern inline int pgd_present(pgd_t pgd)	{ return 1; }
  extern inline void pgd_clear(pgd_t * pgdp)	{ }
  #endif
  
  /*
   * The following only work if pte_present() is true.
   * Undefined behaviour if not..
   */
  extern inline int pte_read(pte_t pte)		{ return pte_val(pte) & _PAGE_READ; }
  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_WRITE; }
  extern inline int pte_file(pte_t pte)		{ return pte_val(pte) & _PAGE_FILE; }
  extern inline int pte_user(pte_t pte) 		{ return pte_val(pte) & _PAGE_USER; }
  
  extern inline pte_t pte_rdprotect(pte_t pte)	{ pte_val(pte) &= ~_PAGE_READ; return pte; }
  extern inline pte_t pte_mkclean(pte_t pte)	{ pte_val(pte) &= ~_PAGE_DIRTY; return pte; }
  extern inline pte_t pte_mkold(pte_t pte)	{ pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
  extern inline pte_t pte_wrprotect(pte_t pte)	{ pte_val(pte) &= ~_PAGE_WRITE; return pte; }
  extern inline pte_t pte_mkread(pte_t pte)	{ pte_val(pte) |= _PAGE_READ; return pte; }
  extern inline pte_t pte_mkdirty(pte_t pte)	{ pte_val(pte) |= _PAGE_DIRTY; return pte; }
  extern inline pte_t pte_mkyoung(pte_t pte)	{ pte_val(pte) |= _PAGE_ACCESSED; return pte; }
  extern inline pte_t pte_mkwrite(pte_t pte)	{ pte_val(pte) |= _PAGE_WRITE; return 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.
   */
  #define __mk_pte(addr,pgprot) \
  ({									\
  	pte_t __pte;							\
  									\
  	pte_val(__pte) = ((addr)+pgprot_val(pgprot));			\
  									\
  	__pte;								\
  })
  
  #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))
  
  static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot)
  {
  	pte_t pte;
  	pte_val(pte) = (pfn << PAGE_SHIFT) | pgprot_val(pgprot);
  	return pte;
  }
  
  /* This takes a physical page address that is used by the remapping functions */
  #define mk_pte_phys(physpage, pgprot) \
  ({ pte_t __pte; pte_val(__pte) = physpage + pgprot_val(pgprot); __pte; })
  
  extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
  { pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot); return pte; }
  
  /* Permanent address of a page.  On parisc we don't have highmem. */
  
  #define pte_pfn(x) (pte_val(x) >> PAGE_SHIFT)
  
  #ifdef CONFIG_DISCONTIGMEM
  #define pte_page(x) (phys_to_page(pte_val(x)))
  #else
  #define pte_page(x) (mem_map+(pte_val(x) >> PAGE_SHIFT))
  #endif
  
  #define pmd_page_kernel(pmd)	((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
  
  #define __pmd_page(pmd) ((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
  #define pmd_page(pmd)	virt_to_page((void *)__pmd_page(pmd))
  
  #define pgd_index(address) ((address) >> PGDIR_SHIFT)
  
  /* to find an entry in a page-table-directory */
  #define pgd_offset(mm, address) \
  ((mm)->pgd + ((address) >> PGDIR_SHIFT))
  
  /* to find an entry in a kernel page-table-directory */
  #define pgd_offset_k(address) pgd_offset(&init_mm, address)
  
  /* Find an entry in the second-level page table.. */
  
  #ifdef __LP64__
  #define pmd_offset(dir,address) \
  ((pmd_t *) pgd_page(*(dir)) + (((address)>>PMD_SHIFT) & (PTRS_PER_PMD-1)))
  #else
  #define pmd_offset(dir,addr) ((pmd_t *) dir)
  #endif
  
  /* Find an entry in the third-level page table.. */ 
  #define pte_index(address) (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE-1))
  #define pte_offset_kernel(pmd, address) \
  	((pte_t *) pmd_page_kernel(*(pmd)) + pte_index(address))
  #define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
  #define pte_offset_map_nested(pmd, address) pte_offset_kernel(pmd, address)
  #define pte_unmap(pte) do { } while (0)
  #define pte_unmap_nested(pte) do { } while (0)
  
  #define pte_unmap(pte)			do { } while (0)
  #define pte_unmap_nested(pte)		do { } while (0)
  
  extern void paging_init (void);
  
  /* Used for deferring calls to flush_dcache_page() */
  
  #define PG_dcache_dirty         PG_arch_1
  
  struct vm_area_struct; /* forward declaration (include/linux/mm.h) */
  extern void update_mmu_cache(struct vm_area_struct *, unsigned long, pte_t);
  
  /* Encode and de-code a swap entry */
  
  #define __swp_type(x)                     ((x).val & 0x1f)
  #define __swp_offset(x)                   ( (((x).val >> 6) &  0x7) | \
  					  (((x).val >> 8) & ~0x7) )
  #define __swp_entry(type, offset)         ((swp_entry_t) { (type) | \
  					    ((offset &  0x7) << 6) | \
  					    ((offset & ~0x7) << 8) })
  #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) })
  #define __swp_entry_to_pte(x)		((pte_t) { (x).val })
  
  static inline int ptep_test_and_clear_young(pte_t *ptep)
  {
  #ifdef CONFIG_SMP
  	return test_and_clear_bit(xlate_pabit(_PAGE_ACCESSED_BIT), ptep);
  #else
  	pte_t pte = *ptep;
  	if (!pte_young(pte))
  		return 0;
  	set_pte(ptep, pte_mkold(pte));
  	return 1;
  #endif
  }
  
  static inline int ptep_test_and_clear_dirty(pte_t *ptep)
  {
  #ifdef CONFIG_SMP
  	return test_and_clear_bit(xlate_pabit(_PAGE_DIRTY_BIT), ptep);
  #else
  	pte_t pte = *ptep;
  	if (!pte_dirty(pte))
  		return 0;
  	set_pte(ptep, pte_mkclean(pte));
  	return 1;
  #endif
  }
  
  #ifdef CONFIG_SMP
  extern spinlock_t pa_dbit_lock;
  #else
  static int pa_dbit_lock; /* dummy to keep the compilers happy */
  #endif
  
  static inline pte_t ptep_get_and_clear(pte_t *ptep)
  {
  	pte_t old_pte;
  	pte_t pte;
  
  	spin_lock(&pa_dbit_lock);
  	pte = old_pte = *ptep;
  	pte_val(pte) &= ~_PAGE_PRESENT;
  	pte_val(pte) |= _PAGE_FLUSH;
  	set_pte(ptep,pte);
  	spin_unlock(&pa_dbit_lock);
  
  	return old_pte;
  }
  
  static inline void ptep_set_wrprotect(pte_t *ptep)
  {
  #ifdef CONFIG_SMP
  	unsigned long new, old;
  
  	do {
  		old = pte_val(*ptep);
  		new = pte_val(pte_wrprotect(__pte (old)));
  	} while (cmpxchg((unsigned long *) ptep, old, new) != old);
  #else
  	pte_t old_pte = *ptep;
  	set_pte(ptep, pte_wrprotect(old_pte));
  #endif
  }
  
  static inline void ptep_mkdirty(pte_t *ptep)
  {
  #ifdef CONFIG_SMP
  	set_bit(xlate_pabit(_PAGE_DIRTY_BIT), ptep);
  #else
  	pte_t old_pte = *ptep;
  	set_pte(ptep, pte_mkdirty(old_pte));
  #endif
  }
  
  #define pte_same(A,B)	(pte_val(A) == pte_val(B))
  
  typedef pte_t *pte_addr_t;
  
  #endif /* !__ASSEMBLY__ */
  
  #define io_remap_page_range remap_page_range
  
  /* We provide our own get_unmapped_area to provide cache coherency */
  
  #define HAVE_ARCH_UNMAPPED_AREA
  
  #endif /* _PARISC_PGTABLE_H */
  