pgtable.h

基于组件方式开发操作系统的OSKIT源代码

/* to find an entry in a page-table */
#define PAGE_PTR(address) \
((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)

/* to set the page-dir */
#define SET_PAGE_DIR(tsk,pgdir) \
do { \
	unsigned long __pgdir = __pa(pgdir); \
	(tsk)->tss.cr3 = __pgdir; \
	if ((tsk) == current) \
		__asm__ __volatile__("movl %0,%%cr3": :"r" (__pgdir)); \
} while (0)

#define pte_none(x)	(!pte_val(x))
#define pte_present(x)	(pte_val(x) & (_PAGE_PRESENT | _PAGE_PROTNONE))
#define pte_clear(xp)	do { pte_val(*(xp)) = 0; } while (0)

#define pmd_none(x)	(!pmd_val(x))
#define	pmd_bad(x)	((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
#define pmd_present(x)	(pmd_val(x) & _PAGE_PRESENT)
#define pmd_clear(xp)	do { pmd_val(*(xp)) = 0; } while (0)

/*
 * 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; }
extern inline void pgd_clear(pgd_t * pgdp)	{ }

/*
 * 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_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 int pte_write(pte_t pte)		{ return pte_val(pte) & _PAGE_RW; }

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_mkclean(pte_t pte)	{ pte_val(pte) &= ~_PAGE_DIRTY; return pte; }
extern inline pte_t pte_mkold(pte_t pte)	{ pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
extern inline pte_t pte_wrprotect(pte_t pte)	{ pte_val(pte) &= ~_PAGE_RW; 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_mkdirty(pte_t pte)	{ pte_val(pte) |= _PAGE_DIRTY; return pte; }
extern inline pte_t pte_mkyoung(pte_t pte)	{ pte_val(pte) |= _PAGE_ACCESSED; return pte; }
extern inline pte_t pte_mkwrite(pte_t pte)	{ pte_val(pte) |= _PAGE_RW; return pte; }

/*
 * 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) \
({ pte_t __pte; pte_val(__pte) = __pa(page) + pgprot_val(pgprot); __pte; })

/* This takes a physical page address that is used by the remapping functions */
#define mk_pte_phys(physpage, pgprot) \
({ pte_t __pte; pte_val(__pte) = physpage + 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 pte_page(pte) \
((unsigned long) __va(pte_val(pte) & PAGE_MASK))

#define pmd_page(pmd) \
((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))

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

/* to find an entry in a kernel page-table-directory */
#define pgd_offset_k(address) pgd_offset(&init_mm, 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.. */ 
#define pte_offset(pmd, address) \
((pte_t *) (pmd_page(*pmd) + ((address>>10) & ((PTRS_PER_PTE-1)<<2))))

/*
 * Allocate and free page tables. The xxx_kernel() versions are
 * used to allocate a kernel page table - this turns on ASN bits
 * if any.
 */

#define pgd_quicklist (current_cpu_data.pgd_quick)
#define pmd_quicklist ((unsigned long *)0)
#define pte_quicklist (current_cpu_data.pte_quick)
#define pgtable_cache_size (current_cpu_data.pgtable_cache_sz)

extern __inline__ pgd_t *get_pgd_slow(void)
{
	pgd_t *ret = (pgd_t *)__get_free_page(GFP_KERNEL), *init;

	if (ret) {
		init = pgd_offset(&init_mm, 0);
		memset (ret, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
		memcpy (ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
			(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
	}
	return ret;
}

extern __inline__ pgd_t *get_pgd_fast(void)
{
	unsigned long *ret;

	if((ret = pgd_quicklist) != NULL) {
		pgd_quicklist = (unsigned long *)(*ret);
		ret[0] = ret[1];
		pgtable_cache_size--;
	} else
		ret = (unsigned long *)get_pgd_slow();
	return (pgd_t *)ret;
}

extern __inline__ void free_pgd_fast(pgd_t *pgd)
{
	*(unsigned long *)pgd = (unsigned long) pgd_quicklist;
	pgd_quicklist = (unsigned long *) pgd;
	pgtable_cache_size++;
}

extern __inline__ void free_pgd_slow(pgd_t *pgd)
{
	free_page((unsigned long)pgd);
}

extern pte_t *get_pte_slow(pmd_t *pmd, unsigned long address_preadjusted);
extern pte_t *get_pte_kernel_slow(pmd_t *pmd, unsigned long address_preadjusted);

extern __inline__ pte_t *get_pte_fast(void)
{
	unsigned long *ret;

	if((ret = (unsigned long *)pte_quicklist) != NULL) {
		pte_quicklist = (unsigned long *)(*ret);
		ret[0] = ret[1];
		pgtable_cache_size--;
	}
	return (pte_t *)ret;
}

extern __inline__ void free_pte_fast(pte_t *pte)
{
	*(unsigned long *)pte = (unsigned long) pte_quicklist;
	pte_quicklist = (unsigned long *) pte;
	pgtable_cache_size++;
}

extern __inline__ void free_pte_slow(pte_t *pte)
{
	free_page((unsigned long)pte);
}

/* We don't use pmd cache, so these are dummy routines */
extern __inline__ pmd_t *get_pmd_fast(void)
{
	return (pmd_t *)0;
}

extern __inline__ void free_pmd_fast(pmd_t *pmd)
{
}

extern __inline__ void free_pmd_slow(pmd_t *pmd)
{
}

extern void __bad_pte(pmd_t *pmd);
extern void __bad_pte_kernel(pmd_t *pmd);

#define pte_free_kernel(pte)    free_pte_fast(pte)
#define pte_free(pte)           free_pte_fast(pte)
#define pgd_free(pgd)           free_pgd_fast(pgd)
#define pgd_alloc()             get_pgd_fast()

extern inline pte_t * pte_alloc_kernel(pmd_t * pmd, unsigned long address)
{
	address = (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
	if (pmd_none(*pmd)) {
		pte_t * page = (pte_t *) get_pte_fast();
		
		if (!page)
			return get_pte_kernel_slow(pmd, address);
		pmd_val(*pmd) = _KERNPG_TABLE + __pa(page);
		return page + address;
	}
	if (pmd_bad(*pmd)) {
		__bad_pte_kernel(pmd);
		return NULL;
	}
	return (pte_t *) pmd_page(*pmd) + address;
}

extern inline pte_t * pte_alloc(pmd_t * pmd, unsigned long address)
{
	address = (address >> (PAGE_SHIFT-2)) & 4*(PTRS_PER_PTE - 1);

	if (pmd_none(*pmd))
		goto getnew;
	if (pmd_bad(*pmd))
		goto fix;
	return (pte_t *) (pmd_page(*pmd) + address);
getnew:
{
	unsigned long page = (unsigned long) get_pte_fast();
	
	if (!page)
		return get_pte_slow(pmd, address);
	pmd_val(*pmd) = _PAGE_TABLE + __pa(page);
	return (pte_t *) (page + address);
}
fix:
	__bad_pte(pmd);
	return NULL;
}

/*
 * allocating and freeing a pmd is trivial: the 1-entry pmd is
 * inside the pgd, so has no extra memory associated with it.
 */
extern inline void pmd_free(pmd_t * pmd)
{
}

extern inline pmd_t * pmd_alloc(pgd_t * pgd, unsigned long address)
{
	return (pmd_t *) pgd;
}

#define pmd_free_kernel		pmd_free
#define pmd_alloc_kernel	pmd_alloc

extern int do_check_pgt_cache(int, int);

extern inline void set_pgdir(unsigned long address, pgd_t entry)
{
	struct task_struct * p;
	pgd_t *pgd;
#ifdef __SMP__
	int i;
#endif	
        
	read_lock(&tasklist_lock);
	for_each_task(p) {
		if (!p->mm)
			continue;
		*pgd_offset(p->mm,address) = entry;
	}
	read_unlock(&tasklist_lock);
#ifndef __SMP__
	for (pgd = (pgd_t *)pgd_quicklist; pgd; pgd = (pgd_t *)*(unsigned long *)pgd)
		pgd[address >> PGDIR_SHIFT] = entry;
#else
	/* To pgd_alloc/pgd_free, one holds master kernel lock and so does our callee, so we can
	   modify pgd caches of other CPUs as well. -jj */
	for (i = 0; i < NR_CPUS; i++)
		for (pgd = (pgd_t *)cpu_data[i].pgd_quick; pgd; pgd = (pgd_t *)*(unsigned long *)pgd)
			pgd[address >> PGDIR_SHIFT] = entry;
#endif
}

extern pgd_t swapper_pg_dir[1024];

/*
 * The i386 doesn't have any external MMU info: the kernel page
 * tables contain all the necessary information.
 */
extern inline void update_mmu_cache(struct vm_area_struct * vma,
	unsigned long address, pte_t pte)
{
}

#define SWP_TYPE(entry) (((entry) >> 1) & 0x3f)
#define SWP_OFFSET(entry) ((entry) >> 8)
#define SWP_ENTRY(type,offset) (((type) << 1) | ((offset) << 8))

#define module_map      vmalloc
#define module_unmap    vfree

#endif /* !__ASSEMBLY__ */
#endif /* !OSKIT */

/* 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)

#endif /* _I386_PAGE_H */