include/asm-arm26/pgtable.h - kernel/msm-4.9 - Gitiles

 /*
  *  linux/include/asm-arm26/pgtable.h
  *
  *  Copyright (C) 2000-2002 Russell King
  *  Copyright (C) 2003 Ian Molton
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 #ifndef _ASMARM_PGTABLE_H
 #define _ASMARM_PGTABLE_H

 #include <asm-generic/4level-fixup.h>

 #include <asm/memory.h>

 /*
  * The table below defines the page protection levels that we insert into our
  * Linux page table version.  These get translated into the best that the
  * architecture can perform.  Note that on most ARM hardware:
  *  1) We cannot do execute protection
  *  2) If we could do execute protection, then read is implied
  *  3) write implies read permissions
  */
 #define __P000  PAGE_NONE
 #define __P001  PAGE_READONLY
 #define __P010  PAGE_COPY
 #define __P011  PAGE_COPY
 #define __P100  PAGE_READONLY
 #define __P101  PAGE_READONLY
 #define __P110  PAGE_COPY
 #define __P111  PAGE_COPY

 #define __S000  PAGE_NONE
 #define __S001  PAGE_READONLY
 #define __S010  PAGE_SHARED
 #define __S011  PAGE_SHARED
 #define __S100  PAGE_READONLY
 #define __S101  PAGE_READONLY
 #define __S110  PAGE_SHARED
 #define __S111  PAGE_SHARED

 /*
  * PMD_SHIFT determines the size of the area a second-level page table can map
  * PGDIR_SHIFT determines what a third-level page table entry can map
  */
 #define PGD_SHIFT		25
 #define PMD_SHIFT		20

 #define PGD_SIZE                (1UL << PGD_SHIFT)
 #define PGD_MASK                (~(PGD_SIZE-1))
 #define PMD_SIZE                (1UL << PMD_SHIFT)
 #define PMD_MASK                (~(PMD_SIZE-1))

 /* The kernel likes to use these names for the above (ick) */
 #define PGDIR_SIZE PGD_SIZE
 #define PGDIR_MASK PGD_MASK

 #define PTRS_PER_PGD            32
 #define PTRS_PER_PMD            1
 #define PTRS_PER_PTE            32

 /*
  * This is the lowest virtual address we can permit any user space
  * mapping to be mapped at.  This is particularly important for
  * non-high vector CPUs.
  */
 #define FIRST_USER_ADDRESS	PAGE_SIZE

 #define FIRST_USER_PGD_NR       1
 #define USER_PTRS_PER_PGD       ((TASK_SIZE/PGD_SIZE) - FIRST_USER_PGD_NR)

 // FIXME - WTF?
 #define LIBRARY_TEXT_START	0x0c000000


 #ifndef __ASSEMBLY__
 extern void __pte_error(const char *file, int line, unsigned long val);
 extern void __pmd_error(const char *file, int line, unsigned long val);
 extern void __pgd_error(const char *file, int line, unsigned long val);

 #define pte_ERROR(pte)		__pte_error(__FILE__, __LINE__, pte_val(pte))
 #define pmd_ERROR(pmd)		__pmd_error(__FILE__, __LINE__, pmd_val(pmd))
 #define pgd_ERROR(pgd)		__pgd_error(__FILE__, __LINE__, pgd_val(pgd))

 /*
  * ZERO_PAGE is a global shared page that is always zero: used
  * for zero-mapped memory areas etc..
  */
 extern struct page *empty_zero_page;
 #define ZERO_PAGE(vaddr)	(empty_zero_page)

 #define pte_pfn(pte)		(pte_val(pte) >> PAGE_SHIFT)
 #define pte_page(pte)           (pfn_to_page(pte_pfn(pte)))
 #define pfn_pte(pfn,prot)	(__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot)))
 #define pages_to_mb(x)		((x) >> (20 - PAGE_SHIFT))
 #define mk_pte(page,prot)	pfn_pte(page_to_pfn(page),prot)

 /*
  * Terminology: PGD = Page Directory, PMD = Page Middle Directory,
  *              PTE = Page Table Entry
  *
  * on arm26 we have no 2nd level page table. we simulate this by removing the
  * PMD.
  *
  * pgd_none is 0 to prevernt pmd_alloc() calling __pmd_alloc(). This causes it
  * to return pmd_offset(pgd,addr) which is a pointer to the pgd (IOW, a no-op).
  *
  * however, to work this way, whilst we are allocating 32 pgds, containing 32
  * PTEs, the actual work is done on the PMDs, thus:
  *
  * instead of  mm->pgd->pmd->pte
  * we have     mm->pgdpmd->pte
  *
  * IOW, think of PGD operations and PMD ones as being the same thing, just
  * that PGD stuff deals with the mm_struct side of things, wheras PMD stuff
  * deals with the pte side of things.
  *
  * additionally, we store some bits in the PGD and PTE pointers:
  * PGDs:
  *   o The lowest (1) bit of the PGD is to determine if it is present or swap.
  *   o The 2nd bit of the PGD is unused and must be zero.
  *   o The top 6 bits of the PGD must be zero.
  * PTEs:
  *   o The lower 5 bits of a pte are flags. bit 1 is the 'present' flag. The
  *     others determine the pages attributes.
  *
  * the pgd_val, pmd_val, and pte_val macros seem to be private to our code.
  * They get the RAW value of the PGD/PMD/PTE entry, including our flags
  * encoded into the pointers.
  *
  * The pgd_offset, pmd_offset, and pte_offset macros are used by the kernel,
  * so they shouldnt have our flags attached.
  *
  * If you understood that, feel free to explain it to me...
  *
  */

 #define _PMD_PRESENT     (0x01)

 /* These definitions allow us to optimise out stuff like pmd_alloc() */
 #define pgd_none(pgd)		(0)
 #define pgd_bad(pgd)		(0)
 #define pgd_present(pgd)	(1)
 #define pgd_clear(pgdp)		do { } while (0)

 /* Whilst these handle our actual 'page directory' (the agglomeration of pgd and pmd)
  */
 #define pmd_none(pmd)           (!pmd_val(pmd))
 #define pmd_bad(pmd)            ((pmd_val(pmd) & 0xfc000002))
 #define pmd_present(pmd)        (pmd_val(pmd) & _PMD_PRESENT)
 #define set_pmd(pmd_ptr, pmd)   ((*(pmd_ptr)) = (pmd))
 #define pmd_clear(pmdp)         set_pmd(pmdp, __pmd(0))

 /* and these handle our pte tables */
 #define pte_none(pte)           (!pte_val(pte))
 #define pte_present(pte)        (pte_val(pte) & _PAGE_PRESENT)
 #define set_pte(pte_ptr, pte)   ((*(pte_ptr)) = (pte))
 #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
 #define pte_clear(mm,addr,ptep)	set_pte_at((mm),(addr),(ptep), __pte(0))

 /* macros to ease the getting of pointers to stuff... */
 #define pgd_offset(mm, addr)	((pgd_t *)(mm)->pgd        + __pgd_index(addr))
 #define pmd_offset(pgd, addr)	((pmd_t *)(pgd))
 #define pte_offset(pmd, addr)   ((pte_t *)pmd_page(*(pmd)) + __pte_index(addr))

 /* there is no __pmd_index as we dont use pmds */
 #define __pgd_index(addr)	((addr) >> PGD_SHIFT)
 #define __pte_index(addr)	(((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))


 /* Keep the kernel happy */
 #define pgd_index(addr)         __pgd_index(addr)
 #define pgd_offset_k(addr)	(pgd_offset(&init_mm, addr))

 /*
  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
  * area for the same reason. ;) FIXME: surely 1 page not 4k ?
  */
 #define VMALLOC_START     0x01a00000
 #define VMALLOC_END       0x01c00000

 /* Is pmd_page supposed to return a pointer to a page in some arches? ours seems to
  * return a pointer to memory (no special alignment)
  */
 #define pmd_page(pmd)  ((struct page *)(pmd_val((pmd)) & ~_PMD_PRESENT))
 #define pmd_page_vaddr(pmd) ((pte_t *)(pmd_val((pmd)) & ~_PMD_PRESENT))

 #define pte_offset_kernel(dir,addr)     (pmd_page_vaddr(*(dir)) + __pte_index(addr))

 #define pte_offset_map(dir,addr)        (pmd_page_vaddr(*(dir)) + __pte_index(addr))
 #define pte_offset_map_nested(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr))
 #define pte_unmap(pte)                  do { } while (0)
 #define pte_unmap_nested(pte)           do { } while (0)


 #define _PAGE_PRESENT   0x01
 #define _PAGE_READONLY  0x02
 #define _PAGE_NOT_USER  0x04
 #define _PAGE_OLD       0x08
 #define _PAGE_CLEAN     0x10

 // an old page has never been read.
 // a clean page has never been written.

 /*                               -- present --   -- !dirty --  --- !write ---   ---- !user --- */
 #define PAGE_NONE       __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY | _PAGE_NOT_USER)
 #define PAGE_SHARED     __pgprot(_PAGE_PRESENT | _PAGE_CLEAN                                  )
 #define PAGE_COPY       __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY                 )
 #define PAGE_READONLY   __pgprot(_PAGE_PRESENT | _PAGE_CLEAN | _PAGE_READONLY                 )
 #define PAGE_KERNEL     __pgprot(_PAGE_PRESENT                                | _PAGE_NOT_USER)

 #define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_OLD | _PAGE_CLEAN)

 /*
  * The following only work if pte_present() is true.
  * Undefined behaviour if not..
  */
 #define pte_write(pte)                  (!(pte_val(pte) & _PAGE_READONLY))
 #define pte_dirty(pte)                  (!(pte_val(pte) & _PAGE_CLEAN))
 #define pte_young(pte)                  (!(pte_val(pte) & _PAGE_OLD))
 //ONLY when !pte_present() I think. nicked from arm32 (FIXME!)
 #define pte_file(pte)                   (!(pte_val(pte) & _PAGE_OLD))

 #define PTE_BIT_FUNC(fn,op)                     \
 static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }

 PTE_BIT_FUNC(wrprotect, |=  _PAGE_READONLY);
 PTE_BIT_FUNC(mkwrite,   &= ~_PAGE_READONLY);
 PTE_BIT_FUNC(mkclean,   |=  _PAGE_CLEAN);
 PTE_BIT_FUNC(mkdirty,   &= ~_PAGE_CLEAN);
 PTE_BIT_FUNC(mkold,     |=  _PAGE_OLD);
 PTE_BIT_FUNC(mkyoung,   &= ~_PAGE_OLD);

 /*
  * We don't store cache state bits in the page table here. FIXME - or do we?
  */
 #define pgprot_noncached(prot)  (prot)
 #define pgprot_writecombine(prot) (prot) //FIXME - is a no-op?

 extern void pgtable_cache_init(void);

 //FIXME - nicked from arm32 and brutally hacked. probably wrong.
 #define pte_to_pgoff(x) (pte_val(x) >> 2)
 #define pgoff_to_pte(x) __pte(((x) << 2) & ~_PAGE_OLD)

 //FIXME - next line borrowed from arm32. is it right?
 #define PTE_FILE_MAX_BITS       30


 static 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;
 }

 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];

 /* Encode and decode a swap entry.
  *
  * We support up to 32GB of swap on 4k machines
  */
 #define __swp_type(x)		(((x).val >> 2) & 0x7f)
 #define __swp_offset(x)		((x).val >> 9)
 #define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 2) | ((offset) << 9) })
 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
 #define __swp_entry_to_pte(swp)	((pte_t) { (swp).val })

 /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
 /* FIXME: this is not correct */
 #define kern_addr_valid(addr)	(1)

 /*
  * Conversion functions: convert a page and protection to a page entry,
  * and a page entry and page directory to the page they refer to.
  */
 static inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)
 {
         pte_t pte;
         pte_val(pte) = physpage | pgprot_val(pgprot);
         return pte;
 }


 #include <asm-generic/pgtable.h>

 /*
  * remap a physical page `pfn' of size `size' with page protection `prot'
  * into virtual address `from'
  */
 #define io_remap_pfn_range(vma,from,pfn,size,prot) \
 		remap_pfn_range(vma, from, pfn, size, prot)

 #endif /* !__ASSEMBLY__ */

 #endif /* _ASMARM_PGTABLE_H */
	/*
	* linux/include/asm-arm26/pgtable.h
	*
	* Copyright (C) 2000-2002 Russell King
	* Copyright (C) 2003 Ian Molton
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/
	#ifndef _ASMARM_PGTABLE_H
	#define _ASMARM_PGTABLE_H

	#include <asm-generic/4level-fixup.h>

	#include <asm/memory.h>

	/*
	* The table below defines the page protection levels that we insert into our
	* Linux page table version. These get translated into the best that the
	* architecture can perform. Note that on most ARM hardware:
	* 1) We cannot do execute protection
	* 2) If we could do execute protection, then read is implied
	* 3) write implies read permissions
	*/
	#define __P000 PAGE_NONE
	#define __P001 PAGE_READONLY
	#define __P010 PAGE_COPY
	#define __P011 PAGE_COPY
	#define __P100 PAGE_READONLY
	#define __P101 PAGE_READONLY
	#define __P110 PAGE_COPY
	#define __P111 PAGE_COPY

	#define __S000 PAGE_NONE
	#define __S001 PAGE_READONLY
	#define __S010 PAGE_SHARED
	#define __S011 PAGE_SHARED
	#define __S100 PAGE_READONLY
	#define __S101 PAGE_READONLY
	#define __S110 PAGE_SHARED
	#define __S111 PAGE_SHARED

	/*
	* PMD_SHIFT determines the size of the area a second-level page table can map
	* PGDIR_SHIFT determines what a third-level page table entry can map
	*/
	#define PGD_SHIFT 25
	#define PMD_SHIFT 20

	#define PGD_SIZE (1UL << PGD_SHIFT)
	#define PGD_MASK (~(PGD_SIZE-1))
	#define PMD_SIZE (1UL << PMD_SHIFT)
	#define PMD_MASK (~(PMD_SIZE-1))

	/* The kernel likes to use these names for the above (ick) */
	#define PGDIR_SIZE PGD_SIZE
	#define PGDIR_MASK PGD_MASK

	#define PTRS_PER_PGD 32
	#define PTRS_PER_PMD 1
	#define PTRS_PER_PTE 32

	/*
	* This is the lowest virtual address we can permit any user space
	* mapping to be mapped at. This is particularly important for
	* non-high vector CPUs.
	*/
	#define FIRST_USER_ADDRESS PAGE_SIZE

	#define FIRST_USER_PGD_NR 1
	#define USER_PTRS_PER_PGD ((TASK_SIZE/PGD_SIZE) - FIRST_USER_PGD_NR)

	// FIXME - WTF?
	#define LIBRARY_TEXT_START 0x0c000000



	#ifndef __ASSEMBLY__
	extern void __pte_error(const char *file, int line, unsigned long val);
	extern void __pmd_error(const char *file, int line, unsigned long val);
	extern void __pgd_error(const char *file, int line, unsigned long val);

	#define pte_ERROR(pte) __pte_error(__FILE__, __LINE__, pte_val(pte))
	#define pmd_ERROR(pmd) __pmd_error(__FILE__, __LINE__, pmd_val(pmd))
	#define pgd_ERROR(pgd) __pgd_error(__FILE__, __LINE__, pgd_val(pgd))

	/*
	* ZERO_PAGE is a global shared page that is always zero: used
	* for zero-mapped memory areas etc..
	*/
	extern struct page *empty_zero_page;
	#define ZERO_PAGE(vaddr) (empty_zero_page)

	#define pte_pfn(pte) (pte_val(pte) >> PAGE_SHIFT)
	#define pte_page(pte) (pfn_to_page(pte_pfn(pte)))
	#define pfn_pte(pfn,prot) (__pte(((pfn) << PAGE_SHIFT) \| pgprot_val(prot)))
	#define pages_to_mb(x) ((x) >> (20 - PAGE_SHIFT))
	#define mk_pte(page,prot) pfn_pte(page_to_pfn(page),prot)

	/*
	* Terminology: PGD = Page Directory, PMD = Page Middle Directory,
	* PTE = Page Table Entry
	*
	* on arm26 we have no 2nd level page table. we simulate this by removing the
	* PMD.
	*
	* pgd_none is 0 to prevernt pmd_alloc() calling __pmd_alloc(). This causes it
	* to return pmd_offset(pgd,addr) which is a pointer to the pgd (IOW, a no-op).
	*
	* however, to work this way, whilst we are allocating 32 pgds, containing 32
	* PTEs, the actual work is done on the PMDs, thus:
	*
	* instead of mm->pgd->pmd->pte
	* we have mm->pgdpmd->pte
	*
	* IOW, think of PGD operations and PMD ones as being the same thing, just
	* that PGD stuff deals with the mm_struct side of things, wheras PMD stuff
	* deals with the pte side of things.
	*
	* additionally, we store some bits in the PGD and PTE pointers:
	* PGDs:
	* o The lowest (1) bit of the PGD is to determine if it is present or swap.
	* o The 2nd bit of the PGD is unused and must be zero.
	* o The top 6 bits of the PGD must be zero.
	* PTEs:
	* o The lower 5 bits of a pte are flags. bit 1 is the 'present' flag. The
	* others determine the pages attributes.
	*
	* the pgd_val, pmd_val, and pte_val macros seem to be private to our code.
	* They get the RAW value of the PGD/PMD/PTE entry, including our flags
	* encoded into the pointers.
	*
	* The pgd_offset, pmd_offset, and pte_offset macros are used by the kernel,
	* so they shouldnt have our flags attached.
	*
	* If you understood that, feel free to explain it to me...
	*
	*/

	#define _PMD_PRESENT (0x01)

	/* These definitions allow us to optimise out stuff like pmd_alloc() */
	#define pgd_none(pgd) (0)
	#define pgd_bad(pgd) (0)
	#define pgd_present(pgd) (1)
	#define pgd_clear(pgdp) do { } while (0)

	/* Whilst these handle our actual 'page directory' (the agglomeration of pgd and pmd)
	*/
	#define pmd_none(pmd) (!pmd_val(pmd))
	#define pmd_bad(pmd) ((pmd_val(pmd) & 0xfc000002))
	#define pmd_present(pmd) (pmd_val(pmd) & _PMD_PRESENT)
	#define set_pmd(pmd_ptr, pmd) ((*(pmd_ptr)) = (pmd))
	#define pmd_clear(pmdp) set_pmd(pmdp, __pmd(0))

	/* and these handle our pte tables */
	#define pte_none(pte) (!pte_val(pte))
	#define pte_present(pte) (pte_val(pte) & _PAGE_PRESENT)
	#define set_pte(pte_ptr, pte) ((*(pte_ptr)) = (pte))
	#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
	#define pte_clear(mm,addr,ptep) set_pte_at((mm),(addr),(ptep), __pte(0))

	/* macros to ease the getting of pointers to stuff... */
	#define pgd_offset(mm, addr) ((pgd_t *)(mm)->pgd + __pgd_index(addr))
	#define pmd_offset(pgd, addr) ((pmd_t *)(pgd))
	#define pte_offset(pmd, addr) ((pte_t )pmd_page((pmd)) + __pte_index(addr))

	/* there is no __pmd_index as we dont use pmds */
	#define __pgd_index(addr) ((addr) >> PGD_SHIFT)
	#define __pte_index(addr) (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))


	/* Keep the kernel happy */
	#define pgd_index(addr) __pgd_index(addr)
	#define pgd_offset_k(addr) (pgd_offset(&init_mm, addr))

	/*
	* The vmalloc() routines leaves a hole of 4kB between each vmalloced
	* area for the same reason. ;) FIXME: surely 1 page not 4k ?
	*/
	#define VMALLOC_START 0x01a00000
	#define VMALLOC_END 0x01c00000

	/* Is pmd_page supposed to return a pointer to a page in some arches? ours seems to
	* return a pointer to memory (no special alignment)
	*/
	#define pmd_page(pmd) ((struct page *)(pmd_val((pmd)) & ~_PMD_PRESENT))
	#define pmd_page_vaddr(pmd) ((pte_t *)(pmd_val((pmd)) & ~_PMD_PRESENT))

	#define pte_offset_kernel(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr))

	#define pte_offset_map(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr))
	#define pte_offset_map_nested(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr))
	#define pte_unmap(pte) do { } while (0)
	#define pte_unmap_nested(pte) do { } while (0)


	#define _PAGE_PRESENT 0x01
	#define _PAGE_READONLY 0x02
	#define _PAGE_NOT_USER 0x04
	#define _PAGE_OLD 0x08
	#define _PAGE_CLEAN 0x10

	// an old page has never been read.
	// a clean page has never been written.

	/* -- present -- -- !dirty -- --- !write --- ---- !user --- */
	#define PAGE_NONE __pgprot(_PAGE_PRESENT \| _PAGE_CLEAN \| _PAGE_READONLY \| _PAGE_NOT_USER)
	#define PAGE_SHARED __pgprot(_PAGE_PRESENT \| _PAGE_CLEAN )
	#define PAGE_COPY __pgprot(_PAGE_PRESENT \| _PAGE_CLEAN \| _PAGE_READONLY )
	#define PAGE_READONLY __pgprot(_PAGE_PRESENT \| _PAGE_CLEAN \| _PAGE_READONLY )
	#define PAGE_KERNEL __pgprot(_PAGE_PRESENT \| _PAGE_NOT_USER)

	#define _PAGE_CHG_MASK (PAGE_MASK \| _PAGE_OLD \| _PAGE_CLEAN)

	/*
	* The following only work if pte_present() is true.
	* Undefined behaviour if not..
	*/
	#define pte_write(pte) (!(pte_val(pte) & _PAGE_READONLY))
	#define pte_dirty(pte) (!(pte_val(pte) & _PAGE_CLEAN))
	#define pte_young(pte) (!(pte_val(pte) & _PAGE_OLD))
	//ONLY when !pte_present() I think. nicked from arm32 (FIXME!)
	#define pte_file(pte) (!(pte_val(pte) & _PAGE_OLD))

	#define PTE_BIT_FUNC(fn,op) \
	static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }

	PTE_BIT_FUNC(wrprotect, \|= _PAGE_READONLY);
	PTE_BIT_FUNC(mkwrite, &= ~_PAGE_READONLY);
	PTE_BIT_FUNC(mkclean, \|= _PAGE_CLEAN);
	PTE_BIT_FUNC(mkdirty, &= ~_PAGE_CLEAN);
	PTE_BIT_FUNC(mkold, \|= _PAGE_OLD);
	PTE_BIT_FUNC(mkyoung, &= ~_PAGE_OLD);

	/*
	* We don't store cache state bits in the page table here. FIXME - or do we?
	*/
	#define pgprot_noncached(prot) (prot)
	#define pgprot_writecombine(prot) (prot) //FIXME - is a no-op?

	extern void pgtable_cache_init(void);

	//FIXME - nicked from arm32 and brutally hacked. probably wrong.
	#define pte_to_pgoff(x) (pte_val(x) >> 2)
	#define pgoff_to_pte(x) __pte(((x) << 2) & ~_PAGE_OLD)

	//FIXME - next line borrowed from arm32. is it right?
	#define PTE_FILE_MAX_BITS 30


	static 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;
	}

	extern pgd_t swapper_pg_dir[PTRS_PER_PGD];

	/* Encode and decode a swap entry.
	*
	* We support up to 32GB of swap on 4k machines
	*/
	#define __swp_type(x) (((x).val >> 2) & 0x7f)
	#define __swp_offset(x) ((x).val >> 9)
	#define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 2) \| ((offset) << 9) })
	#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
	#define __swp_entry_to_pte(swp) ((pte_t) { (swp).val })

	/* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
	/* FIXME: this is not correct */
	#define kern_addr_valid(addr) (1)

	/*
	* Conversion functions: convert a page and protection to a page entry,
	* and a page entry and page directory to the page they refer to.
	*/
	static inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)
	{
	pte_t pte;
	pte_val(pte) = physpage \| pgprot_val(pgprot);
	return pte;
	}


	#include <asm-generic/pgtable.h>

	/*
	* remap a physical page `pfn' of size `size' with page protection `prot'
	* into virtual address `from'
	*/
	#define io_remap_pfn_range(vma,from,pfn,size,prot) \
	remap_pfn_range(vma, from, pfn, size, prot)

	#endif /* !__ASSEMBLY__ */

	#endif /* _ASMARM_PGTABLE_H */