pgtable.h

讲述linux的初始化过程

/*
 * The PowerPC can only do execute protection on a segment (256MB) basis,
 * not on a page basis.  So we consider execute permission the same as 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
#define __P101	PAGE_READONLY
#define __P110	PAGE_COPY
#define __P111	PAGE_COPY

#define __S000	PAGE_NONE
#define __S001	PAGE_READONLY
#define __S010	PAGE_SHARED
#define __S011	PAGE_SHARED
#define __S100	PAGE_READONLY
#define __S101	PAGE_READONLY
#define __S110	PAGE_SHARED
#define __S111	PAGE_SHARED

#ifndef __ASSEMBLY__
/*
 * ZERO_PAGE is a global shared page that is always zero: used
 * for zero-mapped memory areas etc..
 */
extern unsigned long empty_zero_page[1024];
#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))

/*
 * BAD_PAGETABLE is used when we need a bogus page-table, while
 * BAD_PAGE is used for a bogus page.
 *
 * ZERO_PAGE is a global shared page that is always zero: used
 * for zero-mapped memory areas etc..
 */
extern pte_t __bad_page(void);
extern pte_t * __bad_pagetable(void);

#define BAD_PAGETABLE	__bad_pagetable()
#define BAD_PAGE	__bad_page()
#endif /* __ASSEMBLY__ */

/* number of bits that fit into a memory pointer */
#define BITS_PER_PTR	(8*sizeof(unsigned long))

/* to align the pointer to a pointer address */
#define PTR_MASK	(~(sizeof(void*)-1))

/* sizeof(void*) == 1<<SIZEOF_PTR_LOG2 */
/* 64-bit machines, beware!  SRB. */
#define SIZEOF_PTR_LOG2	2

#define pte_none(pte)		(!pte_val(pte))
#define pte_present(pte)	(pte_val(pte) & _PAGE_PRESENT)
#define pte_clear(ptep)		do { pte_val(*(ptep)) = 0; } while (0)

#define pmd_none(pmd)		(!pmd_val(pmd))
#define	pmd_bad(pmd)		((pmd_val(pmd) & ~PAGE_MASK) != 0)
#define	pmd_present(pmd)	((pmd_val(pmd) & PAGE_MASK) != 0)
#define	pmd_clear(pmdp)		do { pmd_val(*(pmdp)) = 0; } while (0)

/*
 * Permanent address of a page.
 */
#define page_address(page)  ((page)->virtual)
#define pages_to_mb(x)		((x) >> (20-PAGE_SHIFT))
#define pte_page(x)		(mem_map+(unsigned long)((pte_val(x) >> PAGE_SHIFT)))

#ifndef __ASSEMBLY__
/*
 * The "pgd_xxx()" functions here are trivial for a folded two-level
 * setup: the pgd is never bad, and a pmd always exists (as it's folded
 * into the pgd entry)
 */
extern inline int pgd_none(pgd_t pgd)		{ return 0; }
extern inline int pgd_bad(pgd_t pgd)		{ return 0; }
extern inline int pgd_present(pgd_t pgd)	{ return 1; }
#define pgd_clear(xp)				do { } while (0)

#define pgd_page(pgd) \
	((unsigned long) __va(pgd_val(pgd) & PAGE_MASK))

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

extern inline void pte_uncache(pte_t pte)       { pte_val(pte) |= _PAGE_NO_CACHE; }
extern inline void pte_cache(pte_t pte)         { pte_val(pte) &= ~_PAGE_NO_CACHE; }

extern inline pte_t pte_rdprotect(pte_t pte) {
	pte_val(pte) &= ~_PAGE_USER; return pte; }
extern inline pte_t pte_exprotect(pte_t pte) {
	pte_val(pte) &= ~_PAGE_USER; return pte; }
extern inline pte_t pte_wrprotect(pte_t pte) {
	pte_val(pte) &= ~(_PAGE_RW | _PAGE_HWWRITE); return pte; }
extern inline pte_t pte_mkclean(pte_t pte) {
	pte_val(pte) &= ~(_PAGE_DIRTY | _PAGE_HWWRITE); return pte; }
extern inline pte_t pte_mkold(pte_t pte) {
	pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }

extern inline pte_t pte_mkread(pte_t pte) {
	pte_val(pte) |= _PAGE_USER; return pte; }
extern inline pte_t pte_mkexec(pte_t pte) {
	pte_val(pte) |= _PAGE_USER; return pte; }
extern inline pte_t pte_mkwrite(pte_t pte)
{
	pte_val(pte) |= _PAGE_RW;
	if (pte_val(pte) & _PAGE_DIRTY)
		pte_val(pte) |= _PAGE_HWWRITE;
	return pte;
}
extern inline pte_t pte_mkdirty(pte_t pte)
{
	pte_val(pte) |= _PAGE_DIRTY;
	if (pte_val(pte) & _PAGE_RW)
		pte_val(pte) |= _PAGE_HWWRITE;
	return pte;
}
extern inline pte_t pte_mkyoung(pte_t pte) {
	pte_val(pte) |= _PAGE_ACCESSED; return pte; }

/* Certain architectures need to do special things when pte's
 * within a page table are directly modified.  Thus, the following
 * hook is made available.
 */
#define set_pte(pteptr, pteval)	((*(pteptr)) = (pteval))

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

extern inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)
{
	pte_t pte;
	pte_val(pte) = physpage | pgprot_val(pgprot);
	return pte;
}

#define mk_pte(page,pgprot) \
({									\
	pte_t pte;							\
	pte_val(pte) = ((page - mem_map) << PAGE_SHIFT) | pgprot_val(pgprot); \
	pte;							\
})

extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
	pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot);
	return pte;
}

#define pmd_page(pmd)	(pmd_val(pmd))

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

/* to find an entry in a page-table-directory */
#define pgd_index(address)	 ((address) >> PGDIR_SHIFT)
#define pgd_offset(mm, address)	 ((mm)->pgd + pgd_index(address))

/* Find an entry in the second-level page table.. */
extern inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)
{
	return (pmd_t *) dir;
}

/* Find an entry in the third-level page table.. */ 
extern inline pte_t * pte_offset(pmd_t * dir, unsigned long address)
{
	return (pte_t *) pmd_page(*dir) + ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1));
}

extern pgd_t swapper_pg_dir[1024];
extern void paging_init(void);

/*
 * Page tables may have changed.  We don't need to do anything here
 * as entries are faulted into the hash table by the low-level
 * data/instruction access exception handlers.
 */
#define update_mmu_cache(vma, addr, pte)	do { } while (0)

/*
 * When flushing the tlb entry for a page, we also need to flush the
 * hash table entry.  flush_hash_page is assembler (for speed) in head.S.
 */
extern void flush_hash_segments(unsigned low_vsid, unsigned high_vsid);
extern void flush_hash_page(unsigned context, unsigned long va);

/* Encode and de-code a swap entry */
#define SWP_TYPE(entry)			(((entry).val >> 1) & 0x3f)
#define SWP_OFFSET(entry)		((entry).val >> 8)
#define SWP_ENTRY(type, offset)		((swp_entry_t) { ((type) << 1) | ((offset) << 8) })
#define pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) })
#define swp_entry_to_pte(x)		((pte_t) { (x).val })

/* CONFIG_APUS */
/* For virtual address to physical address conversion */
extern void cache_clear(__u32 addr, int length);
extern void cache_push(__u32 addr, int length);
extern int mm_end_of_chunk (unsigned long addr, int len);
extern unsigned long iopa(unsigned long addr);
extern unsigned long mm_ptov(unsigned long addr) __attribute__ ((const));

/* Values for nocacheflag and cmode */
/* These are not used by the APUS kernel_map, but prevents
   compilation errors. */
#define	KERNELMAP_FULL_CACHING		0
#define	KERNELMAP_NOCACHE_SER		1
#define	KERNELMAP_NOCACHE_NONSER	2
#define	KERNELMAP_NO_COPYBACK		3

/*
 * Map some physical address range into the kernel address space.
 */
extern unsigned long kernel_map(unsigned long paddr, unsigned long size,
				int nocacheflag, unsigned long *memavailp );

/*
 * Set cache mode of (kernel space) address range. 
 */
extern void kernel_set_cachemode (unsigned long address, unsigned long size,
                                 unsigned int cmode);

/* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
#define PageSkip(page)		(0)
#define kern_addr_valid(addr)	(1)

#define io_remap_page_range remap_page_range 

#include <asm-generic/pgtable.h>

#endif __ASSEMBLY__
#endif /* _PPC_PGTABLE_H */
#endif /* __KERNEL__ */