pgtable.h

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

{
	return (pmd_val(pmd) & (~PAGE_MASK & ~_PAGE_TABLE_INV)) != _PAGE_TABLE;
}

extern inline int pte_present(pte_t pte) { return pte_val(pte) & _PAGE_PRESENT; }
extern inline int pte_none(pte_t pte)
{
	return ((pte_val(pte) & 
                (_PAGE_INVALID | _PAGE_RO | _PAGE_PRESENT)) == _PAGE_INVALID);
}

#define pte_same(a,b)	(pte_val(a) == pte_val(b))

/*
 * query functions pte_write/pte_dirty/pte_young only work if
 * pte_present() is true. Undefined behaviour if not..
 */
extern inline int pte_write(pte_t pte)
{
	return (pte_val(pte) & _PAGE_RO) == 0;
}

extern inline int pte_dirty(pte_t pte)
{
	int skey;

	asm volatile ("iske %0,%1" : "=d" (skey) : "a" (pte_val(pte)));
	return skey & _PAGE_CHANGED;
}

extern inline int pte_young(pte_t pte)
{
	int skey;

	asm volatile ("iske %0,%1" : "=d" (skey) : "a" (pte_val(pte)));
	return skey & _PAGE_REFERENCED;
}

/*
 * pgd/pmd/pte modification functions
 */
extern inline void pgd_clear(pgd_t * pgdp)      { }

extern inline void pmd_clear(pmd_t * pmdp)
{
	pmd_val(pmdp[0]) = _PAGE_TABLE_INV;
	pmd_val(pmdp[1]) = _PAGE_TABLE_INV;
	pmd_val(pmdp[2]) = _PAGE_TABLE_INV;
	pmd_val(pmdp[3]) = _PAGE_TABLE_INV;
}

extern inline void pte_clear(pte_t *ptep)
{
	pte_val(*ptep) = _PAGE_INVALID; 
}

#define PTE_INIT(x) pte_clear(x)

/*
 * The following pte modification functions only work if
 * pte_present() is true. Undefined behaviour if not..
 */
extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
	pte_val(pte) = (pte_val(pte) & PAGE_MASK) | pgprot_val(newprot);
	return pte;
}

extern inline pte_t pte_wrprotect(pte_t pte)
{
	pte_val(pte) |= _PAGE_RO;
	return pte;
}

extern inline pte_t pte_mkwrite(pte_t pte) 
{
	pte_val(pte) &= ~_PAGE_RO;
	return pte;
}

extern inline pte_t pte_mkclean(pte_t pte)
{
	/* The only user of pte_mkclean is the fork() code.
	   We must *not* clear the *physical* page dirty bit
	   just because fork() wants to clear the dirty bit in
	   *one* of the page's mappings.  So we just do nothing. */
	return pte;
}

extern inline pte_t pte_mkdirty(pte_t pte)
{
	/* We can't set the changed bit atomically. For now we
         * set (!) the page referenced bit. */
	asm volatile ("sske %0,%1" 
	              : : "d" (_PAGE_CHANGED|_PAGE_REFERENCED),
		          "a" (pte_val(pte)));

	pte_val(pte) &= ~_PAGE_MKCLEAR;
	return pte;
}

extern inline pte_t pte_mkold(pte_t pte)
{
	asm volatile ("rrbe 0,%0" : : "a" (pte_val(pte)) : "cc" );
	return pte;
}

extern inline pte_t pte_mkyoung(pte_t pte)
{
	/* To set the referenced bit we read the first word from the real
	 * page with a special instruction: load using real address (lura).
	 * Isn't S/390 a nice architecture ?! */
	asm volatile ("lura 0,%0" : : "a" (pte_val(pte) & PAGE_MASK) : "0" );
	return pte;
}

static inline int ptep_test_and_clear_young(pte_t *ptep)
{
	int ccode;

	asm volatile ("rrbe 0,%1\n\t"
		      "ipm  %0\n\t"
		      "srl  %0,28\n\t" 
                      : "=d" (ccode) : "a" (pte_val(*ptep)) : "cc" );
	return ccode & 2;
}

static inline int ptep_test_and_clear_dirty(pte_t *ptep)
{
	int skey;

	asm volatile ("iske %0,%1" : "=d" (skey) : "a" (*ptep));
	if ((skey & _PAGE_CHANGED) == 0)
		return 0;
	/* We can't clear the changed bit atomically. For now we
         * clear (!) the page referenced bit. */
	asm volatile ("sske %0,%1" 
	              : : "d" (0), "a" (*ptep));
	return 1;
}

static inline pte_t ptep_get_and_clear(pte_t *ptep)
{
	pte_t pte = *ptep;
	pte_clear(ptep);
	return pte;
}

static inline void ptep_set_wrprotect(pte_t *ptep)
{
	pte_t old_pte = *ptep;
	set_pte(ptep, pte_wrprotect(old_pte));
}

static inline void ptep_mkdirty(pte_t *ptep)
{
	pte_mkdirty(*ptep);
}

/*
 * 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(pg, pgprot)                                                \
({                                                                        \
	struct page *__page = (pg);                                       \
	unsigned long __physpage = __pa((__page-mem_map) << PAGE_SHIFT);  \
	pte_t __pte = mk_pte_phys(__physpage, (pgprot));                  \
	                                                                  \
	if (__page != ZERO_PAGE(__physpage)) {                            \
		int __users = page_count(__page);                         \
		__users -= !!__page->buffers + !!__page->mapping;         \
	                                                                  \
		if (__users == 1)                                         \
			pte_val(__pte) |= _PAGE_MKCLEAR;                  \
        }                                                                 \
	                                                                  \
	__pte;                                                            \
})

#define pte_page(x) (mem_map+(unsigned long)((pte_val(x) >> PAGE_SHIFT)))

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

/* to find an entry in a page-table-directory */
#define pgd_index(address) ((address >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
#define pgd_offset(mm, address) ((mm)->pgd+pgd_index(address))

/* 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))))

/*
 * A page-table entry has some bits we have to treat in a special way.
 * Bits 0, 20 and bit 23 have to be zero, otherwise an specification
 * exception will occur instead of a page translation exception. The
 * specifiation exception has the bad habit not to store necessary
 * information in the lowcore.
 * Bit 21 and bit 22 are the page invalid bit and the page protection
 * bit. We set both to indicate a swapped page.
 * Bit 31 is used as the software page present bit. If a page is
 * swapped this obviously has to be zero.
 * This leaves the bits 1-19 and bits 24-30 to store type and offset.
 * We use the 7 bits from 24-30 for the type and the 19 bits from 1-19
 * for the offset.
 * 0|     offset      |0110|type |0
 * 00000000001111111111222222222233
 * 01234567890123456789012345678901
 */
extern inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
{
	pte_t pte;
	pte_val(pte) = (type << 1) | (offset << 12) | _PAGE_INVALID | _PAGE_RO;
	pte_val(pte) &= 0x7ffff6fe;  /* better to be paranoid */
	return pte;
}

#define SWP_TYPE(entry)		(((entry).val >> 1) & 0x3f)
#define SWP_OFFSET(entry)	(((entry).val >> 12) & 0x7FFFF )
#define SWP_ENTRY(type,offset)	((swp_entry_t) { pte_val(mk_swap_pte((type),(offset))) })

#define pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
#define swp_entry_to_pte(x)	((pte_t) { (x).val })

#endif /* !__ASSEMBLY__ */

/* 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)

/*
 * No page table caches to initialise
 */
#define pgtable_cache_init()	do { } while (0)

#endif /* _S390_PAGE_H */