linux/include/asm-i386/pgtable.h

#ifndef _I386_PGTABLE_H
#define _I386_PGTABLE_H

#include <linux/config.h>

/*
 * The Linux memory management assumes a three-level page table setup. On
 * the i386, we use that, but "fold" the mid level into the top-level page
 * table, so that we physically have the same two-level page table as the
 * i386 mmu expects.
 *
 * This file contains the functions and defines necessary to modify and use
 * the i386 page table tree.
 */
#ifndef __ASSEMBLY__
#include <asm/processor.h>
#include <asm/fixmap.h>
#include <linux/threads.h>

#ifndef _I386_BITOPS_H
#include <asm/bitops.h>
#endif

#include <linux/slab.h>
#include <linux/list.h>
#include <linux/spinlock.h>

/*
 * 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))
extern unsigned long empty_zero_page[1024];
extern pgd_t swapper_pg_dir[1024];
extern kmem_cache_t *pgd_cache;
extern kmem_cache_t *pmd_cache;
extern spinlock_t pgd_lock;
extern struct page *pgd_list;

void pmd_ctor(void *, kmem_cache_t *, unsigned long);
void pgd_ctor(void *, kmem_cache_t *, unsigned long);
void pgd_dtor(void *, kmem_cache_t *, unsigned long);
void pgtable_cache_init(void);
void paging_init(void);

/*
 * The Linux x86 paging architecture is 'compile-time dual-mode', it
 * implements both the traditional 2-level x86 page tables and the
 * newer 3-level PAE-mode page tables.
 */
#ifdef CONFIG_X86_PAE
# include <asm/pgtable-3level-defs.h>
# define PMD_SIZE	(1UL << PMD_SHIFT)
# define PMD_MASK	(~(PMD_SIZE-1))
#else
# include <asm/pgtable-2level-defs.h>
#endif

#define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
#define PGDIR_MASK	(~(PGDIR_SIZE-1))

#define USER_PTRS_PER_PGD	(TASK_SIZE/PGDIR_SIZE)
#define FIRST_USER_PGD_NR	0

#define USER_PGD_PTRS (PAGE_OFFSET >> PGDIR_SHIFT)
#define KERNEL_PGD_PTRS (PTRS_PER_PGD-USER_PGD_PTRS)

#define TWOLEVEL_PGDIR_SHIFT	22
#define BOOT_USER_PGD_PTRS (__PAGE_OFFSET >> TWOLEVEL_PGDIR_SHIFT)
#define BOOT_KERNEL_PGD_PTRS (1024-BOOT_USER_PGD_PTRS)

/* 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_earlyreserve + \
			2*VMALLOC_OFFSET-1) & ~(VMALLOC_OFFSET-1))
#ifdef CONFIG_HIGHMEM
# define VMALLOC_END	(PKMAP_BASE-2*PAGE_SIZE)
#else
# define VMALLOC_END	(FIXADDR_START-2*PAGE_SIZE)
#endif

/*
 * The 4MB page is guessing..  Detailed in the infamous "Chapter H"
 * of the Pentium details, but assuming intel did the straightforward
 * thing, this bit set in the page directory entry just means that
 * the page directory entry points directly to a 4MB-aligned block of
 * memory. 
 */
#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, Pentium+, if present.. */
#define _PAGE_BIT_GLOBAL	8	/* Global TLB entry PPro+ */
#define _PAGE_BIT_UNUSED1	9	/* available for programmer */
#define _PAGE_BIT_UNUSED2	10
#define _PAGE_BIT_UNUSED3	11
#define _PAGE_BIT_NX		63

#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	/* 4 MB (or 2MB) page, Pentium+, if present.. */
#define _PAGE_GLOBAL	0x100	/* Global TLB entry PPro+ */
#define _PAGE_UNUSED1	0x200	/* available for programmer */
#define _PAGE_UNUSED2	0x400
#define _PAGE_UNUSED3	0x800

#define _PAGE_FILE	0x040	/* set:pagecache unset:swap */
#define _PAGE_PROTNONE	0x080	/* If not present */
#ifdef CONFIG_X86_PAE
#define _PAGE_NX	(1ULL<<_PAGE_BIT_NX)
#else
#define _PAGE_NX	0
#endif

#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)

#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_EXEC \
	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
#define PAGE_COPY \
	PAGE_COPY_NOEXEC
#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)

extern unsigned long long __PAGE_KERNEL, __PAGE_KERNEL_EXEC;
#define __PAGE_KERNEL_RO		(__PAGE_KERNEL & ~_PAGE_RW)
#define __PAGE_KERNEL_NOCACHE		(__PAGE_KERNEL | _PAGE_PCD)
#define __PAGE_KERNEL_LARGE		(__PAGE_KERNEL | _PAGE_PSE)
#define __PAGE_KERNEL_LARGE_EXEC	(__PAGE_KERNEL_EXEC | _PAGE_PSE)

#define PAGE_KERNEL		__pgprot(__PAGE_KERNEL)
#define PAGE_KERNEL_RO		__pgprot(__PAGE_KERNEL_RO)
#define PAGE_KERNEL_EXEC	__pgprot(__PAGE_KERNEL_EXEC)
#define PAGE_KERNEL_NOCACHE	__pgprot(__PAGE_KERNEL_NOCACHE)
#define PAGE_KERNEL_LARGE	__pgprot(__PAGE_KERNEL_LARGE)
#define PAGE_KERNEL_LARGE_EXEC	__pgprot(__PAGE_KERNEL_LARGE_EXEC)

/*
 * The i386 can't do page protection for execute, and considers that
 * the same are read. Also, write permissions imply read permissions.
 * This is the closest we can get..
 */
#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

/*
 * Define this if things work differently on an i386 and an i486:
 * it will (on an i486) warn about kernel memory accesses that are
 * done without a 'verify_area(VERIFY_WRITE,..)'
 */
#undef TEST_VERIFY_AREA

/* The boot page tables (all created as a single array) */
extern unsigned long pg0[];

#define pte_present(x)	((x).pte_low & (_PAGE_PRESENT | _PAGE_PROTNONE))
#define pte_clear(mm,addr,xp)	do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)

#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	pmd_bad(x)	((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)


#define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT))

/*
 * The following only work if pte_present() is true.
 * Undefined behaviour if not..
 */
static inline int pte_user(pte_t pte)		{ return (pte).pte_low & _PAGE_USER; }
static inline int pte_read(pte_t pte)		{ return (pte).pte_low & _PAGE_USER; }
static inline int pte_dirty(pte_t pte)		{ return (pte).pte_low & _PAGE_DIRTY; }
static inline int pte_young(pte_t pte)		{ return (pte).pte_low & _PAGE_ACCESSED; }
static inline int pte_write(pte_t pte)		{ return (pte).pte_low & _PAGE_RW; }

/*
 * The following only works if pte_present() is not true.
 */
static inline int pte_file(pte_t pte)		{ return (pte).pte_low & _PAGE_FILE; }

static inline pte_t pte_rdprotect(pte_t pte)	{ (pte).pte_low &= ~_PAGE_USER; return pte; }
static inline pte_t pte_exprotect(pte_t pte)	{ (pte).pte_low &= ~_PAGE_USER; return pte; }
static inline pte_t pte_mkclean(pte_t pte)	{ (pte).pte_low &= ~_PAGE_DIRTY; return pte; }
static inline pte_t pte_mkold(pte_t pte)	{ (pte).pte_low &= ~_PAGE_ACCESSED; return pte; }
static inline pte_t pte_wrprotect(pte_t pte)	{ (pte).pte_low &= ~_PAGE_RW; return pte; }
static inline pte_t pte_mkread(pte_t pte)	{ (pte).pte_low |= _PAGE_USER; return pte; }
static inline pte_t pte_mkexec(pte_t pte)	{ (pte).pte_low |= _PAGE_USER; return pte; }
static inline pte_t pte_mkdirty(pte_t pte)	{ (pte).pte_low |= _PAGE_DIRTY; return pte; }
static inline pte_t pte_mkyoung(pte_t pte)	{ (pte).pte_low |= _PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkwrite(pte_t pte)	{ (pte).pte_low |= _PAGE_RW; return pte; }

#ifdef CONFIG_X86_PAE
# include <asm/pgtable-3level.h>
#else
# include <asm/pgtable-2level.h>
#endif

static inline int ptep_test_and_clear_dirty(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
{
	if (!pte_dirty(*ptep))
		return 0;
	return test_and_clear_bit(_PAGE_BIT_DIRTY, &ptep->pte_low);
}

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_low);
}

static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
	clear_bit(_PAGE_BIT_RW, &ptep->pte_low);
}

/*
 * Macro to mark a page protection value as "uncacheable".  On processors which do not support
 * it, this is a no-op.
 */
#define pgprot_noncached(prot)	((boot_cpu_data.x86 > 3)					  \
				 ? (__pgprot(pgprot_val(prot) | _PAGE_PCD | _PAGE_PWT)) : (prot))

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

static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
	pte.pte_low &= _PAGE_CHG_MASK;
	pte.pte_low |= pgprot_val(newprot);
#ifdef CONFIG_X86_PAE
	/*
	 * Chop off the NX bit (if present), and add the NX portion of
	 * the newprot (if present):
	 */
	pte.pte_high &= ~(1 << (_PAGE_BIT_NX - 32));
	pte.pte_high |= (pgprot_val(newprot) >> 32) & \
					(__supported_pte_mask >> 32);
#endif
	return pte;
}

#define page_pte(page) page_pte_prot(page, __pgprot(0))

#define pmd_large(pmd) \
((pmd_val(pmd) & (_PAGE_PSE|_PAGE_PRESENT)) == (_PAGE_PSE|_PAGE_PRESENT))

/*
 * the pgd page can be thought of an array like this: pgd_t[PTRS_PER_PGD]
 *
 * this macro returns the index of the entry in the pgd page which would
 * control the given virtual address
 */
#define pgd_index(address) (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
#define pgd_index_k(addr) pgd_index(addr)

/*
 * pgd_offset() returns a (pgd_t *)
 * pgd_index() is used get the offset into the pgd page's array of pgd_t's;
 */
#define pgd_offset(mm, address) ((mm)->pgd+pgd_index(address))

/*
 * a shortcut which implies the use of the kernel's pgd, instead
 * of a process's
 */
#define pgd_offset_k(address) pgd_offset(&init_mm, address)

/*
 * the pmd page can be thought of an array like this: pmd_t[PTRS_PER_PMD]
 *
 * this macro returns the index of the entry in the pmd page which would
 * control the given virtual address
 */
#define pmd_index(address) \
		(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))

/*
 * the pte page can be thought of an array like this: pte_t[PTRS_PER_PTE]
 *
 * this macro returns the index of the entry in the pte page which would
 * control the given virtual address
 */
#define pte_index(address) \
		(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
#define pte_offset_kernel(dir, address) \
	((pte_t *) pmd_page_kernel(*(dir)) +  pte_index(address))

/*
 * Helper function that returns the kernel pagetable entry controlling
 * the virtual address 'address'. NULL means no pagetable entry present.
 * NOTE: the return type is pte_t but if the pmd is PSE then we return it
 * as a pte too.
 */
extern pte_t *lookup_address(unsigned long address);

/*
 * Make a given kernel text page executable/non-executable.
 * Returns the previous executability setting of that page (which
 * is used to restore the previous state). Used by the SMP bootup code.
 * NOTE: this is an __init function for security reasons.
 */
#ifdef CONFIG_X86_PAE
 extern int set_kernel_exec(unsigned long vaddr, int enable);
#else
 static inline int set_kernel_exec(unsigned long vaddr, int enable) { return 0;}
#endif

extern void noexec_setup(const char *str);

#if defined(CONFIG_HIGHPTE)
#define pte_offset_map(dir, address) \
	((pte_t *)kmap_atomic(pmd_page(*(dir)),KM_PTE0) + pte_index(address))
#define pte_offset_map_nested(dir, address) \
	((pte_t *)kmap_atomic(pmd_page(*(dir)),KM_PTE1) + pte_index(address))
#define pte_unmap(pte) kunmap_atomic(pte, KM_PTE0)
#define pte_unmap_nested(pte) kunmap_atomic(pte, KM_PTE1)
#else
#define pte_offset_map(dir, address) \
	((pte_t *)page_address(pmd_page(*(dir))) + pte_index(address))
#define pte_offset_map_nested(dir, address) pte_offset_map(dir, address)
#define pte_unmap(pte) do { } while (0)
#define pte_unmap_nested(pte) do { } while (0)
#endif

/*
 * The i386 doesn't have any external MMU info: the kernel page
 * tables contain all the necessary information.
 *
 * Also, 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 update_mmu_cache(vma,address,pte) do { } while (0)
#define  __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
	do {								  \
		if (__dirty) {						  \
			(__ptep)->pte_low = (__entry).pte_low;	  	  \
			flush_tlb_page(__vma, __address);		  \
		}							  \
	} while (0)

#endif /* !__ASSEMBLY__ */

#ifndef CONFIG_DISCONTIGMEM
#define kern_addr_valid(addr)	(1)
#endif /* !CONFIG_DISCONTIGMEM */

#define io_remap_page_range(vma, vaddr, paddr, size, prot)		\
		remap_pfn_range(vma, vaddr, (paddr) >> PAGE_SHIFT, size, prot)

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

#define MK_IOSPACE_PFN(space, pfn)	(pfn)
#define GET_IOSPACE(pfn)		0
#define GET_PFN(pfn)			(pfn)

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

#endif /* _I386_PGTABLE_H */