pgalloc-3level.h

来自「讲述linux的初始化过程」· C头文件 代码 · 共 69 行

#ifndef _I386_PGALLOC_3LEVEL_H
#define _I386_PGALLOC_3LEVEL_H

/*
 * Intel Physical Address Extension (PAE) Mode - three-level page
 * tables on PPro+ CPUs. Page-table allocation routines.
 *
 * Copyright (C) 1999 Ingo Molnar <[e-mail]>
 */

extern __inline__ pmd_t *get_pmd_slow(void)
{
	pmd_t *ret = (pmd_t *)__get_free_page(GFP_KERNEL);

	if (ret)
		memset(ret, 0, PAGE_SIZE);
	return ret;
}

extern __inline__ pmd_t *get_pmd_fast(void)
{
	unsigned long *ret;

	if ((ret = pmd_quicklist) != NULL) {
		pmd_quicklist = (unsigned long *)(*ret);
		ret[0] = 0;
		pgtable_cache_size--;
	} else
		ret = (unsigned long *)get_pmd_slow();
	return (pmd_t *)ret;
}

extern __inline__ void free_pmd_fast(pmd_t *pmd)
{
	*(unsigned long *)pmd = (unsigned long) pmd_quicklist;
	pmd_quicklist = (unsigned long *) pmd;
	pgtable_cache_size++;
}

extern __inline__ void free_pmd_slow(pmd_t *pmd)
{
	free_page((unsigned long)pmd);
}

extern inline pmd_t * pmd_alloc(pgd_t *pgd, unsigned long address)
{
	if (!pgd)
		BUG();
	address = (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
	if (pgd_none(*pgd)) {
		pmd_t *page = get_pmd_fast();

		if (!page)
			page = get_pmd_slow();
		if (page) {
			if (pgd_none(*pgd)) {
				set_pgd(pgd, __pgd(1 + __pa(page)));
				__flush_tlb();
				return page + address;
			} else
				free_pmd_fast(page);
		} else
			return NULL;
	}
	return (pmd_t *)pgd_page(*pgd) + address;
}

#endif /* _I386_PGALLOC_3LEVEL_H */