arch/x86/include/asm/pgtable_32.h

#ifndef _ASM_X86_PGTABLE_32_H
#define _ASM_X86_PGTABLE_32_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>
#include <asm/paravirt.h>

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

struct mm_struct;
struct vm_area_struct;

extern pgd_t swapper_pg_dir[1024];

static inline void pgtable_cache_init(void) { }
static inline void check_pgt_cache(void) { }
void paging_init(void);

extern void set_pmd_pfn(unsigned long, unsigned long, pgprot_t);

/*
 * 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_types.h>
# define PMD_SIZE	(1UL << PMD_SHIFT)
# define PMD_MASK	(~(PMD_SIZE - 1))
#else
# include <asm/pgtable-2level_types.h>
#endif

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

/* 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)
#ifdef CONFIG_X86_PAE
#define LAST_PKMAP 512
#else
#define LAST_PKMAP 1024
#endif

#define PKMAP_BASE ((FIXADDR_BOOT_START - PAGE_SIZE * (LAST_PKMAP + 1))	\
		    & PMD_MASK)

#ifdef CONFIG_HIGHMEM
# define VMALLOC_END	(PKMAP_BASE - 2 * PAGE_SIZE)
#else
# define VMALLOC_END	(FIXADDR_START - 2 * PAGE_SIZE)
#endif

#define MAXMEM	(VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE)

/*
 * 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 'access_ok(VERIFY_WRITE,..)'
 */
#undef TEST_ACCESS_OK

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

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

#if defined(CONFIG_HIGHPTE)
#define pte_offset_map(dir, address)					\
	((pte_t *)kmap_atomic_pte(pmd_page(*(dir)), KM_PTE0) +		\
	 pte_index((address)))
#define pte_offset_map_nested(dir, address)				\
	((pte_t *)kmap_atomic_pte(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

/* Clear a kernel PTE and flush it from the TLB */
#define kpte_clear_flush(ptep, vaddr)		\
do {						\
	pte_clear(&init_mm, (vaddr), (ptep));	\
	__flush_tlb_one((vaddr));		\
} while (0)

/*
 * The i386 doesn't have any external MMU info: the kernel page
 * tables contain all the necessary information.
 */
#define update_mmu_cache(vma, address, pte) do { } while (0)

#endif /* !__ASSEMBLY__ */

/*
 * kern_addr_valid() is (1) for FLATMEM and (0) for
 * SPARSEMEM and DISCONTIGMEM
 */
#ifdef CONFIG_FLATMEM
#define kern_addr_valid(addr)	(1)
#else
#define kern_addr_valid(kaddr)	(0)
#endif

#endif /* _ASM_X86_PGTABLE_32_H */