1. 根目录:
2. arch
3. x86
4. include
5. asm
6. pgtable_64.h

#ifndef _ASM_X86_PGTABLE_64_H
#define _ASM_X86_PGTABLE_64_H

#include <linux/const.h>
#include <asm/pgtable_64_types.h>

#ifndef __ASSEMBLY__

/*
 * This file contains the functions and defines necessary to modify and use
 * the x86-64 page table tree.
 */
#include <asm/processor.h>
#include <linux/bitops.h>
#include <linux/threads.h>

extern pud_t level3_kernel_pgt[512];
extern pud_t level3_ident_pgt[512];
extern pmd_t level2_kernel_pgt[512];
extern pmd_t level2_fixmap_pgt[512];
extern pmd_t level2_ident_pgt[512];
extern pte_t level1_fixmap_pgt[512];
extern pgd_t init_level4_pgt[];

#define swapper_pg_dir init_level4_pgt

extern void paging_init(void);

#define pte_ERROR(e)					\
	pr_err("%s:%d: bad pte %p(%016lx)\n",		\
	       __FILE__, __LINE__, &(e), pte_val(e))
#define pmd_ERROR(e)					\
	pr_err("%s:%d: bad pmd %p(%016lx)\n",		\
	       __FILE__, __LINE__, &(e), pmd_val(e))
#define pud_ERROR(e)					\
	pr_err("%s:%d: bad pud %p(%016lx)\n",		\
	       __FILE__, __LINE__, &(e), pud_val(e))
#define pgd_ERROR(e)					\
	pr_err("%s:%d: bad pgd %p(%016lx)\n",		\
	       __FILE__, __LINE__, &(e), pgd_val(e))

struct mm_struct;

void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte);


static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr,
				    pte_t *ptep)
{
	*ptep = native_make_pte(0);
}

static inline void native_set_pte(pte_t *ptep, pte_t pte)
{
	*ptep = pte;
}

static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
{
	native_set_pte(ptep, pte);
}

static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
{
	*pmdp = pmd;
}

static inline void native_pmd_clear(pmd_t *pmd)
{
	native_set_pmd(pmd, native_make_pmd(0));
}

static inline pte_t native_ptep_get_and_clear(pte_t *xp)
{
#ifdef CONFIG_SMP
	return native_make_pte(xchg(&xp->pte, 0));
#else
	/* native_local_ptep_get_and_clear,
	   but duplicated because of cyclic dependency */
	pte_t ret = *xp;
	native_pte_clear(NULL, 0, xp);
	return ret;
#endif
}

static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
{
#ifdef CONFIG_SMP
	return native_make_pmd(xchg(&xp->pmd, 0));
#else
	/* native_local_pmdp_get_and_clear,
	   but duplicated because of cyclic dependency */
	pmd_t ret = *xp;
	native_pmd_clear(xp);
	return ret;
#endif
}

static inline void native_set_pud(pud_t *pudp, pud_t pud)
{
	*pudp = pud;
}

static inline void native_pud_clear(pud_t *pud)
{
	native_set_pud(pud, native_make_pud(0));
}

static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd)
{
	*pgdp = pgd;
}

static inline void native_pgd_clear(pgd_t *pgd)
{
	native_set_pgd(pgd, native_make_pgd(0));
}

extern void sync_global_pgds(unsigned long start, unsigned long end,
			     int removed);

/*
 * Conversion functions: convert a page and protection to a page entry,
 * and a page entry and page directory to the page they refer to.
 */

/*
 * Level 4 access.
 */
static inline int pgd_large(pgd_t pgd) { return 0; }
#define mk_kernel_pgd(address) __pgd((address) | _KERNPG_TABLE)

/* PUD - Level3 access */

/* PMD  - Level 2 access */
#define pte_to_pgoff(pte) ((pte_val((pte)) & PHYSICAL_PAGE_MASK) >> PAGE_SHIFT)
#define pgoff_to_pte(off) ((pte_t) { .pte = ((off) << PAGE_SHIFT) |	\
					    _PAGE_FILE })
#define PTE_FILE_MAX_BITS __PHYSICAL_MASK_SHIFT

/* PTE - Level 1 access. */

/* x86-64 always has all page tables mapped. */
#define pte_offset_map(dir, address) pte_offset_kernel((dir), (address))
#define pte_unmap(pte) ((void)(pte))/* NOP */

/* Encode and de-code a swap entry */
#define SWP_TYPE_BITS (_PAGE_BIT_FILE - _PAGE_BIT_PRESENT - 1)
#ifdef CONFIG_NUMA_BALANCING
/* Automatic NUMA balancing needs to be distinguishable from swap entries */
#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 2)
#else
#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)
#endif

#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)

#define __swp_type(x)			(((x).val >> (_PAGE_BIT_PRESENT + 1)) \
					 & ((1U << SWP_TYPE_BITS) - 1))
#define __swp_offset(x)			((x).val >> SWP_OFFSET_SHIFT)
#define __swp_entry(type, offset)	((swp_entry_t) { \
					 ((type) << (_PAGE_BIT_PRESENT + 1)) \
					 | ((offset) << SWP_OFFSET_SHIFT) })
#define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val((pte)) })
#define __swp_entry_to_pte(x)		((pte_t) { .pte = (x).val })

extern int kern_addr_valid(unsigned long addr);
extern void cleanup_highmap(void);

#define HAVE_ARCH_UNMAPPED_AREA
#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN

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

#define PAGE_AGP    PAGE_KERNEL_NOCACHE
#define HAVE_PAGE_AGP 1

/* fs/proc/kcore.c */
#define	kc_vaddr_to_offset(v) ((v) & __VIRTUAL_MASK)
#define	kc_offset_to_vaddr(o) ((o) | ~__VIRTUAL_MASK)

#define __HAVE_ARCH_PTE_SAME

#define vmemmap ((struct page *)VMEMMAP_START)

extern void init_extra_mapping_uc(unsigned long phys, unsigned long size);
extern void init_extra_mapping_wb(unsigned long phys, unsigned long size);

#endif /* !__ASSEMBLY__ */

#endif /* _ASM_X86_PGTABLE_64_H */