linux/include/asm-x86/page_64.h

#ifndef _X86_64_PAGE_H
#define _X86_64_PAGE_H

#define PAGETABLE_LEVELS	4

#define THREAD_ORDER	1
#define THREAD_SIZE  (PAGE_SIZE << THREAD_ORDER)
#define CURRENT_MASK (~(THREAD_SIZE - 1))

#define EXCEPTION_STACK_ORDER 0
#define EXCEPTION_STKSZ (PAGE_SIZE << EXCEPTION_STACK_ORDER)

#define DEBUG_STACK_ORDER (EXCEPTION_STACK_ORDER + 1)
#define DEBUG_STKSZ (PAGE_SIZE << DEBUG_STACK_ORDER)

#define IRQSTACK_ORDER 2
#define IRQSTACKSIZE (PAGE_SIZE << IRQSTACK_ORDER)

#define STACKFAULT_STACK 1
#define DOUBLEFAULT_STACK 2
#define NMI_STACK 3
#define DEBUG_STACK 4
#define MCE_STACK 5
#define N_EXCEPTION_STACKS 5  /* hw limit: 7 */

#define PUD_PAGE_SIZE		(_AC(1, UL) << PUD_SHIFT)
#define PUD_PAGE_MASK		(~(PUD_PAGE_SIZE-1))

/*
 * Set __PAGE_OFFSET to the most negative possible address +
 * PGDIR_SIZE*16 (pgd slot 272).  The gap is to allow a space for a
 * hypervisor to fit.  Choosing 16 slots here is arbitrary, but it's
 * what Xen requires.
 */
#define __PAGE_OFFSET           _AC(0xffff880000000000, UL)

#define __PHYSICAL_START	CONFIG_PHYSICAL_START
#define __KERNEL_ALIGN		0x200000

/*
 * Make sure kernel is aligned to 2MB address. Catching it at compile
 * time is better. Change your config file and compile the kernel
 * for a 2MB aligned address (CONFIG_PHYSICAL_START)
 */
#if (CONFIG_PHYSICAL_START % __KERNEL_ALIGN) != 0
#error "CONFIG_PHYSICAL_START must be a multiple of 2MB"
#endif

#define __START_KERNEL		(__START_KERNEL_map + __PHYSICAL_START)
#define __START_KERNEL_map	_AC(0xffffffff80000000, UL)

/* See Documentation/x86_64/mm.txt for a description of the memory map. */
#define __PHYSICAL_MASK_SHIFT	46
#define __VIRTUAL_MASK_SHIFT	48

/*
 * Kernel image size is limited to 512 MB (see level2_kernel_pgt in
 * arch/x86/kernel/head_64.S), and it is mapped here:
 */
#define KERNEL_IMAGE_SIZE	(512 * 1024 * 1024)
#define KERNEL_IMAGE_START	_AC(0xffffffff80000000, UL)

#ifndef __ASSEMBLY__
void clear_page(void *page);
void copy_page(void *to, void *from);

/* duplicated to the one in bootmem.h */
extern unsigned long max_pfn;
extern unsigned long phys_base;

extern unsigned long __phys_addr(unsigned long);
#define __phys_reloc_hide(x)	(x)

/*
 * These are used to make use of C type-checking..
 */
typedef unsigned long	pteval_t;
typedef unsigned long	pmdval_t;
typedef unsigned long	pudval_t;
typedef unsigned long	pgdval_t;
typedef unsigned long	pgprotval_t;
typedef unsigned long	phys_addr_t;

typedef struct page *pgtable_t;

typedef struct { pteval_t pte; } pte_t;

#define vmemmap ((struct page *)VMEMMAP_START)

extern unsigned long init_memory_mapping(unsigned long start,
					 unsigned long end);

extern void initmem_init(unsigned long start_pfn, unsigned long end_pfn);

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__ */

#ifdef CONFIG_FLATMEM
#define pfn_valid(pfn)          ((pfn) < max_pfn)
#endif


#endif /* _X86_64_PAGE_H */