arch/arm/include/asm/pgtable.h - kernel/msm-4.19 - Gitiles

 /*
  *  arch/arm/include/asm/pgtable.h
  *
  *  Copyright (C) 1995-2002 Russell King
  *
  * 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 <linux/const.h>
 #include <asm/proc-fns.h>

 #ifndef CONFIG_MMU

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

 #else

 #include <asm-generic/pgtable-nopud.h>
 #include <asm/memory.h>
 #include <asm/pgtable-hwdef.h>

 #ifdef CONFIG_ARM_LPAE
 #include <asm/pgtable-3level.h>
 #else
 #include <asm/pgtable-2level.h>
 #endif

 /*
  * Just any arbitrary offset to the start of the vmalloc VM area: the
  * current 8MB value just means that there will be a 8MB "hole" after the
  * physical memory until the kernel virtual memory starts.  That means that
  * any out-of-bounds memory accesses will hopefully be caught.
  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
  * area for the same reason. ;)
  */
 #define VMALLOC_OFFSET		(8*1024*1024)
 #define VMALLOC_START		(((unsigned long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
 #define VMALLOC_END		0xff000000UL

 #define LIBRARY_TEXT_START	0x0c000000

 #ifndef __ASSEMBLY__
 extern void __pte_error(const char *file, int line, pte_t);
 extern void __pmd_error(const char *file, int line, pmd_t);
 extern void __pgd_error(const char *file, int line, pgd_t);

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

 /*
  * 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

 /*
  * Use TASK_SIZE as the ceiling argument for free_pgtables() and
  * free_pgd_range() to avoid freeing the modules pmd when LPAE is enabled (pmd
  * page shared between user and kernel).
  */
 #ifdef CONFIG_ARM_LPAE
 #define USER_PGTABLES_CEILING	TASK_SIZE
 #endif

 /*
  * The pgprot_* and protection_map entries will be fixed up in runtime
  * to include the cachable and bufferable bits based on memory policy,
  * as well as any architecture dependent bits like global/ASID and SMP
  * shared mapping bits.
  */
 #define _L_PTE_DEFAULT	L_PTE_PRESENT | L_PTE_YOUNG

 extern pgprot_t		pgprot_user;
 extern pgprot_t		pgprot_kernel;
 extern pgprot_t		pgprot_hyp_device;
 extern pgprot_t		pgprot_s2;
 extern pgprot_t		pgprot_s2_device;

 #define _MOD_PROT(p, b)	__pgprot(pgprot_val(p) | (b))

 #define PAGE_NONE		_MOD_PROT(pgprot_user, L_PTE_XN | L_PTE_RDONLY | L_PTE_NONE)
 #define PAGE_SHARED		_MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_XN)
 #define PAGE_SHARED_EXEC	_MOD_PROT(pgprot_user, L_PTE_USER)
 #define PAGE_COPY		_MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY | L_PTE_XN)
 #define PAGE_COPY_EXEC		_MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY)
 #define PAGE_READONLY		_MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY | L_PTE_XN)
 #define PAGE_READONLY_EXEC	_MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY)
 #define PAGE_KERNEL		_MOD_PROT(pgprot_kernel, L_PTE_XN)
 #define PAGE_KERNEL_EXEC	pgprot_kernel
 #define PAGE_HYP		_MOD_PROT(pgprot_kernel, L_PTE_HYP)
 #define PAGE_HYP_DEVICE		_MOD_PROT(pgprot_hyp_device, L_PTE_HYP)
 #define PAGE_S2			_MOD_PROT(pgprot_s2, L_PTE_S2_RDONLY)
 #define PAGE_S2_DEVICE		_MOD_PROT(pgprot_s2_device, L_PTE_USER | L_PTE_S2_RDONLY)

 #define __PAGE_NONE		__pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN | L_PTE_NONE)
 #define __PAGE_SHARED		__pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN)
 #define __PAGE_SHARED_EXEC	__pgprot(_L_PTE_DEFAULT | L_PTE_USER)
 #define __PAGE_COPY		__pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_RDONLY | L_PTE_XN)
 #define __PAGE_COPY_EXEC	__pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_RDONLY)
 #define __PAGE_READONLY		__pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_RDONLY | L_PTE_XN)
 #define __PAGE_READONLY_EXEC	__pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_RDONLY)

 #define __pgprot_modify(prot,mask,bits)		\
 	__pgprot((pgprot_val(prot) & ~(mask)) | (bits))

 #define pgprot_noncached(prot) \
 	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED)

 #define pgprot_writecombine(prot) \
 	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE)

 #define pgprot_stronglyordered(prot) \
 	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED)

 #ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE
 #define pgprot_dmacoherent(prot) \
 	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE | L_PTE_XN)
 #define __HAVE_PHYS_MEM_ACCESS_PROT
 struct file;
 extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 				     unsigned long size, pgprot_t vma_prot);
 #else
 #define pgprot_dmacoherent(prot) \
 	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED | L_PTE_XN)
 #endif

 #endif /* __ASSEMBLY__ */

 /*
  * 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_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__
 /*
  * 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)


 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];

 /* to find an entry in a page-table-directory */
 #define pgd_index(addr)		((addr) >> PGDIR_SHIFT)

 #define pgd_offset(mm, addr)	((mm)->pgd + pgd_index(addr))

 /* to find an entry in a kernel page-table-directory */
 #define pgd_offset_k(addr)	pgd_offset(&init_mm, addr)

 #define pmd_none(pmd)		(!pmd_val(pmd))
 #define pmd_present(pmd)	(pmd_val(pmd))

 static inline pte_t *pmd_page_vaddr(pmd_t pmd)
 {
 	return __va(pmd_val(pmd) & PHYS_MASK & (s32)PAGE_MASK);
 }

 #define pmd_page(pmd)		pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))

 #ifndef CONFIG_HIGHPTE
 #define __pte_map(pmd)		pmd_page_vaddr(*(pmd))
 #define __pte_unmap(pte)	do { } while (0)
 #else
 #define __pte_map(pmd)		(pte_t *)kmap_atomic(pmd_page(*(pmd)))
 #define __pte_unmap(pte)	kunmap_atomic(pte)
 #endif

 #define pte_index(addr)		(((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))

 #define pte_offset_kernel(pmd,addr)	(pmd_page_vaddr(*(pmd)) + pte_index(addr))

 #define pte_offset_map(pmd,addr)	(__pte_map(pmd) + pte_index(addr))
 #define pte_unmap(pte)			__pte_unmap(pte)

 #define pte_pfn(pte)		((pte_val(pte) & PHYS_MASK) >> PAGE_SHIFT)
 #define pfn_pte(pfn,prot)	__pte(__pfn_to_phys(pfn) | pgprot_val(prot))

 #define pte_page(pte)		pfn_to_page(pte_pfn(pte))
 #define mk_pte(page,prot)	pfn_pte(page_to_pfn(page), prot)

 #define pte_clear(mm,addr,ptep)	set_pte_ext(ptep, __pte(0), 0)

 #define pte_none(pte)		(!pte_val(pte))
 #define pte_present(pte)	(pte_val(pte) & L_PTE_PRESENT)
 #define pte_write(pte)		(!(pte_val(pte) & L_PTE_RDONLY))
 #define pte_dirty(pte)		(pte_val(pte) & L_PTE_DIRTY)
 #define pte_young(pte)		(pte_val(pte) & L_PTE_YOUNG)
 #define pte_exec(pte)		(!(pte_val(pte) & L_PTE_XN))
 #define pte_special(pte)	(0)

 #define pte_present_user(pte)  (pte_present(pte) && (pte_val(pte) & L_PTE_USER))

 #if __LINUX_ARM_ARCH__ < 6
 static inline void __sync_icache_dcache(pte_t pteval)
 {
 }
 #else
 extern void __sync_icache_dcache(pte_t pteval);
 #endif

 static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep, pte_t pteval)
 {
 	unsigned long ext = 0;

 	if (addr < TASK_SIZE && pte_present_user(pteval)) {
 		__sync_icache_dcache(pteval);
 		ext |= PTE_EXT_NG;
 	}

 	set_pte_ext(ptep, pteval, ext);
 }

 #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, |= L_PTE_RDONLY);
 PTE_BIT_FUNC(mkwrite,   &= ~L_PTE_RDONLY);
 PTE_BIT_FUNC(mkclean,   &= ~L_PTE_DIRTY);
 PTE_BIT_FUNC(mkdirty,   |= L_PTE_DIRTY);
 PTE_BIT_FUNC(mkold,     &= ~L_PTE_YOUNG);
 PTE_BIT_FUNC(mkyoung,   |= L_PTE_YOUNG);

 static inline pte_t pte_mkspecial(pte_t pte) { return pte; }

 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
 	const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER |
 		L_PTE_NONE | L_PTE_VALID;
 	pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
 	return pte;
 }

 /*
  * Encode and decode a swap entry.  Swap entries are stored in the Linux
  * page tables as follows:
  *
  *   3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
  *   1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
  *   <--------------- offset ----------------------> < type -> 0 0 0
  *
  * This gives us up to 31 swap files and 64GB per swap file.  Note that
  * the offset field is always non-zero.
  */
 #define __SWP_TYPE_SHIFT	3
 #define __SWP_TYPE_BITS		5
 #define __SWP_TYPE_MASK		((1 << __SWP_TYPE_BITS) - 1)
 #define __SWP_OFFSET_SHIFT	(__SWP_TYPE_BITS + __SWP_TYPE_SHIFT)

 #define __swp_type(x)		(((x).val >> __SWP_TYPE_SHIFT) & __SWP_TYPE_MASK)
 #define __swp_offset(x)		((x).val >> __SWP_OFFSET_SHIFT)
 #define __swp_entry(type,offset) ((swp_entry_t) { ((type) << __SWP_TYPE_SHIFT) | ((offset) << __SWP_OFFSET_SHIFT) })

 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
 #define __swp_entry_to_pte(swp)	((pte_t) { (swp).val })

 /*
  * It is an error for the kernel to have more swap files than we can
  * encode in the PTEs.  This ensures that we know when MAX_SWAPFILES
  * is increased beyond what we presently support.
  */
 #define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > __SWP_TYPE_BITS)

 /*
  * Encode and decode a file entry.  File entries are stored in the Linux
  * page tables as follows:
  *
  *   3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
  *   1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
  *   <----------------------- offset ------------------------> 1 0 0
  */
 #define pte_file(pte)		(pte_val(pte) & L_PTE_FILE)
 #define pte_to_pgoff(x)		(pte_val(x) >> 3)
 #define pgoff_to_pte(x)		__pte(((x) << 3) | L_PTE_FILE)

 #define PTE_FILE_MAX_BITS	29

 /* 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)

 #include <asm-generic/pgtable.h>

 /*
  * We provide our own arch_get_unmapped_area to cope with VIPT caches.
  */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN

 /*
  * 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)

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

 #endif /* !__ASSEMBLY__ */

 #endif /* CONFIG_MMU */

 #endif /* _ASMARM_PGTABLE_H */
	/*
	* arch/arm/include/asm/pgtable.h
	*
	* Copyright (C) 1995-2002 Russell King
	*
	* 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 <linux/const.h>
	#include <asm/proc-fns.h>

	#ifndef CONFIG_MMU

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

	#else

	#include <asm-generic/pgtable-nopud.h>
	#include <asm/memory.h>
	#include <asm/pgtable-hwdef.h>

	#ifdef CONFIG_ARM_LPAE
	#include <asm/pgtable-3level.h>
	#else
	#include <asm/pgtable-2level.h>
	#endif

	/*
	* Just any arbitrary offset to the start of the vmalloc VM area: the
	* current 8MB value just means that there will be a 8MB "hole" after the
	* physical memory until the kernel virtual memory starts. That means that
	* any out-of-bounds memory accesses will hopefully be caught.
	* The vmalloc() routines leaves a hole of 4kB between each vmalloced
	* area for the same reason. ;)
	*/
	#define VMALLOC_OFFSET (810241024)
	#define VMALLOC_START (((unsigned long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
	#define VMALLOC_END 0xff000000UL

	#define LIBRARY_TEXT_START 0x0c000000

	#ifndef __ASSEMBLY__
	extern void __pte_error(const char *file, int line, pte_t);
	extern void __pmd_error(const char *file, int line, pmd_t);
	extern void __pgd_error(const char *file, int line, pgd_t);

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

	/*
	* 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

	/*
	* Use TASK_SIZE as the ceiling argument for free_pgtables() and
	* free_pgd_range() to avoid freeing the modules pmd when LPAE is enabled (pmd
	* page shared between user and kernel).
	*/
	#ifdef CONFIG_ARM_LPAE
	#define USER_PGTABLES_CEILING TASK_SIZE
	#endif

	/*
	* The pgprot_* and protection_map entries will be fixed up in runtime
	* to include the cachable and bufferable bits based on memory policy,
	* as well as any architecture dependent bits like global/ASID and SMP
	* shared mapping bits.
	*/
	#define _L_PTE_DEFAULT L_PTE_PRESENT \| L_PTE_YOUNG

	extern pgprot_t pgprot_user;
	extern pgprot_t pgprot_kernel;
	extern pgprot_t pgprot_hyp_device;
	extern pgprot_t pgprot_s2;
	extern pgprot_t pgprot_s2_device;

	#define _MOD_PROT(p, b) __pgprot(pgprot_val(p) \| (b))

	#define PAGE_NONE _MOD_PROT(pgprot_user, L_PTE_XN \| L_PTE_RDONLY \| L_PTE_NONE)
	#define PAGE_SHARED _MOD_PROT(pgprot_user, L_PTE_USER \| L_PTE_XN)
	#define PAGE_SHARED_EXEC _MOD_PROT(pgprot_user, L_PTE_USER)
	#define PAGE_COPY _MOD_PROT(pgprot_user, L_PTE_USER \| L_PTE_RDONLY \| L_PTE_XN)
	#define PAGE_COPY_EXEC _MOD_PROT(pgprot_user, L_PTE_USER \| L_PTE_RDONLY)
	#define PAGE_READONLY _MOD_PROT(pgprot_user, L_PTE_USER \| L_PTE_RDONLY \| L_PTE_XN)
	#define PAGE_READONLY_EXEC _MOD_PROT(pgprot_user, L_PTE_USER \| L_PTE_RDONLY)
	#define PAGE_KERNEL _MOD_PROT(pgprot_kernel, L_PTE_XN)
	#define PAGE_KERNEL_EXEC pgprot_kernel
	#define PAGE_HYP _MOD_PROT(pgprot_kernel, L_PTE_HYP)
	#define PAGE_HYP_DEVICE _MOD_PROT(pgprot_hyp_device, L_PTE_HYP)
	#define PAGE_S2 _MOD_PROT(pgprot_s2, L_PTE_S2_RDONLY)
	#define PAGE_S2_DEVICE _MOD_PROT(pgprot_s2_device, L_PTE_USER \| L_PTE_S2_RDONLY)

	#define __PAGE_NONE __pgprot(_L_PTE_DEFAULT \| L_PTE_RDONLY \| L_PTE_XN \| L_PTE_NONE)
	#define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT \| L_PTE_USER \| L_PTE_XN)
	#define __PAGE_SHARED_EXEC __pgprot(_L_PTE_DEFAULT \| L_PTE_USER)
	#define __PAGE_COPY __pgprot(_L_PTE_DEFAULT \| L_PTE_USER \| L_PTE_RDONLY \| L_PTE_XN)
	#define __PAGE_COPY_EXEC __pgprot(_L_PTE_DEFAULT \| L_PTE_USER \| L_PTE_RDONLY)
	#define __PAGE_READONLY __pgprot(_L_PTE_DEFAULT \| L_PTE_USER \| L_PTE_RDONLY \| L_PTE_XN)
	#define __PAGE_READONLY_EXEC __pgprot(_L_PTE_DEFAULT \| L_PTE_USER \| L_PTE_RDONLY)

	#define __pgprot_modify(prot,mask,bits) \
	__pgprot((pgprot_val(prot) & ~(mask)) \| (bits))

	#define pgprot_noncached(prot) \
	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED)

	#define pgprot_writecombine(prot) \
	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE)

	#define pgprot_stronglyordered(prot) \
	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED)

	#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE
	#define pgprot_dmacoherent(prot) \
	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE \| L_PTE_XN)
	#define __HAVE_PHYS_MEM_ACCESS_PROT
	struct file;
	extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
	unsigned long size, pgprot_t vma_prot);
	#else
	#define pgprot_dmacoherent(prot) \
	__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED \| L_PTE_XN)
	#endif

	#endif /* __ASSEMBLY__ */

	/*
	* 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_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__
	/*
	* 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)


	extern pgd_t swapper_pg_dir[PTRS_PER_PGD];

	/* to find an entry in a page-table-directory */
	#define pgd_index(addr) ((addr) >> PGDIR_SHIFT)

	#define pgd_offset(mm, addr) ((mm)->pgd + pgd_index(addr))

	/* to find an entry in a kernel page-table-directory */
	#define pgd_offset_k(addr) pgd_offset(&init_mm, addr)

	#define pmd_none(pmd) (!pmd_val(pmd))
	#define pmd_present(pmd) (pmd_val(pmd))

	static inline pte_t *pmd_page_vaddr(pmd_t pmd)
	{
	return __va(pmd_val(pmd) & PHYS_MASK & (s32)PAGE_MASK);
	}

	#define pmd_page(pmd) pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))

	#ifndef CONFIG_HIGHPTE
	#define __pte_map(pmd) pmd_page_vaddr(*(pmd))
	#define __pte_unmap(pte) do { } while (0)
	#else
	#define __pte_map(pmd) (pte_t )kmap_atomic(pmd_page((pmd)))
	#define __pte_unmap(pte) kunmap_atomic(pte)
	#endif

	#define pte_index(addr) (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))

	#define pte_offset_kernel(pmd,addr) (pmd_page_vaddr(*(pmd)) + pte_index(addr))

	#define pte_offset_map(pmd,addr) (__pte_map(pmd) + pte_index(addr))
	#define pte_unmap(pte) __pte_unmap(pte)

	#define pte_pfn(pte) ((pte_val(pte) & PHYS_MASK) >> PAGE_SHIFT)
	#define pfn_pte(pfn,prot) __pte(__pfn_to_phys(pfn) \| pgprot_val(prot))

	#define pte_page(pte) pfn_to_page(pte_pfn(pte))
	#define mk_pte(page,prot) pfn_pte(page_to_pfn(page), prot)

	#define pte_clear(mm,addr,ptep) set_pte_ext(ptep, __pte(0), 0)

	#define pte_none(pte) (!pte_val(pte))
	#define pte_present(pte) (pte_val(pte) & L_PTE_PRESENT)
	#define pte_write(pte) (!(pte_val(pte) & L_PTE_RDONLY))
	#define pte_dirty(pte) (pte_val(pte) & L_PTE_DIRTY)
	#define pte_young(pte) (pte_val(pte) & L_PTE_YOUNG)
	#define pte_exec(pte) (!(pte_val(pte) & L_PTE_XN))
	#define pte_special(pte) (0)

	#define pte_present_user(pte) (pte_present(pte) && (pte_val(pte) & L_PTE_USER))

	#if __LINUX_ARM_ARCH__ < 6
	static inline void __sync_icache_dcache(pte_t pteval)
	{
	}
	#else
	extern void __sync_icache_dcache(pte_t pteval);
	#endif

	static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
	pte_t *ptep, pte_t pteval)
	{
	unsigned long ext = 0;

	if (addr < TASK_SIZE && pte_present_user(pteval)) {
	__sync_icache_dcache(pteval);
	ext \|= PTE_EXT_NG;
	}

	set_pte_ext(ptep, pteval, ext);
	}

	#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, \|= L_PTE_RDONLY);
	PTE_BIT_FUNC(mkwrite, &= ~L_PTE_RDONLY);
	PTE_BIT_FUNC(mkclean, &= ~L_PTE_DIRTY);
	PTE_BIT_FUNC(mkdirty, \|= L_PTE_DIRTY);
	PTE_BIT_FUNC(mkold, &= ~L_PTE_YOUNG);
	PTE_BIT_FUNC(mkyoung, \|= L_PTE_YOUNG);

	static inline pte_t pte_mkspecial(pte_t pte) { return pte; }

	static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
	{
	const pteval_t mask = L_PTE_XN \| L_PTE_RDONLY \| L_PTE_USER \|
	L_PTE_NONE \| L_PTE_VALID;
	pte_val(pte) = (pte_val(pte) & ~mask) \| (pgprot_val(newprot) & mask);
	return pte;
	}

	/*
	* Encode and decode a swap entry. Swap entries are stored in the Linux
	* page tables as follows:
	*
	* 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
	* 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
	* <--------------- offset ----------------------> < type -> 0 0 0
	*
	* This gives us up to 31 swap files and 64GB per swap file. Note that
	* the offset field is always non-zero.
	*/
	#define __SWP_TYPE_SHIFT 3
	#define __SWP_TYPE_BITS 5
	#define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1)
	#define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT)

	#define __swp_type(x) (((x).val >> __SWP_TYPE_SHIFT) & __SWP_TYPE_MASK)
	#define __swp_offset(x) ((x).val >> __SWP_OFFSET_SHIFT)
	#define __swp_entry(type,offset) ((swp_entry_t) { ((type) << __SWP_TYPE_SHIFT) \| ((offset) << __SWP_OFFSET_SHIFT) })

	#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
	#define __swp_entry_to_pte(swp) ((pte_t) { (swp).val })

	/*
	* It is an error for the kernel to have more swap files than we can
	* encode in the PTEs. This ensures that we know when MAX_SWAPFILES
	* is increased beyond what we presently support.
	*/
	#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > __SWP_TYPE_BITS)

	/*
	* Encode and decode a file entry. File entries are stored in the Linux
	* page tables as follows:
	*
	* 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
	* 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
	* <----------------------- offset ------------------------> 1 0 0
	*/
	#define pte_file(pte) (pte_val(pte) & L_PTE_FILE)
	#define pte_to_pgoff(x) (pte_val(x) >> 3)
	#define pgoff_to_pte(x) __pte(((x) << 3) \| L_PTE_FILE)

	#define PTE_FILE_MAX_BITS 29

	/* 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)

	#include <asm-generic/pgtable.h>

	/*
	* We provide our own arch_get_unmapped_area to cope with VIPT caches.
	*/
	#define HAVE_ARCH_UNMAPPED_AREA
	#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN

	/*
	* 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)

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

	#endif /* !__ASSEMBLY__ */

	#endif /* CONFIG_MMU */

	#endif /* _ASMARM_PGTABLE_H */