include/asm-generic/rmap.h

   1 #ifndef _GENERIC_RMAP_H
   2 #define _GENERIC_RMAP_H
   3 /*
   4  * linux/include/asm-generic/rmap.h
   5  *
   6  * Architecture dependent parts of the reverse mapping code,
   7  * this version should work for most architectures with a
   8  * 'normal' page table layout.
   9  *
  10  * We use the struct page of the page table page to find out
  11  * the process and full address of a page table entry:
  12  * - page->mapping points to the process' mm_struct
  13  * - page->index has the high bits of the address
  14  * - the lower bits of the address are calculated from the
  15  *   offset of the page table entry within the page table page
  16  *
  17  * For CONFIG_HIGHPTE, we need to represent the address of a pte in a
  18  * scalar pte_addr_t.  The pfn of the pte's page is shifted left by PAGE_SIZE
  19  * bits and is then ORed with the byte offset of the pte within its page.
  20  *
  21  * For CONFIG_HIGHMEM4G, the pte_addr_t is 32 bits.  20 for the pfn, 12 for
  22  * the offset.
  23  *
  24  * For CONFIG_HIGHMEM64G, the pte_addr_t is 64 bits.  52 for the pfn, 12 for
  25  * the offset.
  26  */
  27 #include <linux/mm.h>
  28
  29 static inline void pgtable_add_rmap(struct page * page, struct mm_struct * mm, unsigned long address)
  30 {
  31 #ifdef BROKEN_PPC_PTE_ALLOC_ONE
  32         /* OK, so PPC calls pte_alloc() before mem_map[] is setup ... ;( */
  33         extern int mem_init_done;
  34
  35         if (!mem_init_done)
  36                 return;
  37 #endif
  38         page->mapping = (void *)mm;
  39         page->index = address & ~((PTRS_PER_PTE * PAGE_SIZE) - 1);
  40         inc_page_state(nr_page_table_pages);
  41 }
  42
  43 static inline void pgtable_remove_rmap(struct page * page)
  44 {
  45         page->mapping = NULL;
  46         page->index = 0;
  47         dec_page_state(nr_page_table_pages);
  48 }
  49
  50 static inline struct mm_struct * ptep_to_mm(pte_t * ptep)
  51 {
  52         struct page * page = kmap_atomic_to_page(ptep);
  53         return (struct mm_struct *) page->mapping;
  54 }
  55
  56 static inline unsigned long ptep_to_address(pte_t * ptep)
  57 {
  58         struct page * page = kmap_atomic_to_page(ptep);
  59         unsigned long low_bits;
  60         low_bits = ((unsigned long)ptep & ~PAGE_MASK) * PTRS_PER_PTE;
  61         return page->index + low_bits;
  62 }
  63
  64 #ifdef CONFIG_HIGHPTE
  65 static inline pte_addr_t ptep_to_paddr(pte_t *ptep)
  66 {
  67         pte_addr_t paddr;
  68         paddr = ((pte_addr_t)page_to_pfn(kmap_atomic_to_page(ptep))) << PAGE_SHIFT;
  69         return paddr + (pte_addr_t)((unsigned long)ptep & ~PAGE_MASK);
  70 }
  71 #else
  72 static inline pte_addr_t ptep_to_paddr(pte_t *ptep)
  73 {
  74         return (pte_addr_t)ptep;
  75 }
  76 #endif
  77
  78 #ifndef CONFIG_HIGHPTE
  79 static inline pte_t *rmap_ptep_map(pte_addr_t pte_paddr)
  80 {
  81         return (pte_t *)pte_paddr;
  82 }
  83
  84 static inline void rmap_ptep_unmap(pte_t *pte)
  85 {
  86         return;
  87 }
  88 #endif
  89
  90 #endif /* _GENERIC_RMAP_H */