include/linux/highmem.h

   1 #ifndef _LINUX_HIGHMEM_H
   2 #define _LINUX_HIGHMEM_H
   3
   4 #include <linux/config.h>
   5 #include <linux/pagemap.h>
   6 #include <asm/pgtable.h>
   7
   8 #ifdef CONFIG_HIGHMEM
   9
  10 extern struct page *highmem_start_page;
  11
  12 #include <asm/highmem.h>
  13
  14 /* declarations for linux/mm/highmem.c */
  15 extern unsigned long highmem_mapnr;
  16 FASTCALL(unsigned int nr_free_highpages(void));
  17
  18 extern struct page * prepare_highmem_swapout(struct page *);
  19 extern struct page * replace_with_highmem(struct page *);
  20 extern struct buffer_head * create_bounce(int rw, struct buffer_head * bh_orig);
  21
  22 #else /* CONFIG_HIGHMEM */
  23
  24 extern inline unsigned int nr_free_highpages(void) { return 0; }
  25 #define prepare_highmem_swapout(page) page
  26 #define replace_with_highmem(page) page
  27 #define kmap(page) page_address(page)
  28 #define kunmap(page) do { } while (0)
  29
  30 #endif /* CONFIG_HIGHMEM */
  31
  32 /* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
  33 extern inline void clear_highpage(struct page *page)
  34 {
  35         unsigned long kaddr;
  36
  37         kaddr = kmap(page);
  38         clear_page((void *)kaddr);
  39         kunmap(page);
  40 }
  41
  42 extern inline void memclear_highpage(struct page *page, unsigned int offset, unsigned int size)
  43 {
  44         unsigned long kaddr;
  45
  46         if (offset + size > PAGE_SIZE)
  47                 BUG();
  48         kaddr = kmap(page);
  49         memset((void *)(kaddr + offset), 0, size);
  50         kunmap(page);
  51 }
  52
  53 /*
  54  * Same but also flushes aliased cache contents to RAM.
  55  */
  56 extern inline void memclear_highpage_flush(struct page *page, unsigned int offset, unsigned int size)
  57 {
  58         unsigned long kaddr;
  59
  60         if (offset + size > PAGE_SIZE)
  61                 BUG();
  62         kaddr = kmap(page);
  63         memset((void *)(kaddr + offset), 0, size);
  64         flush_page_to_ram(page);
  65         kunmap(page);
  66 }
  67
  68 extern inline void copy_highpage(struct page *to, struct page *from)
  69 {
  70         unsigned long vfrom, vto;
  71
  72         vfrom = kmap(from);
  73         vto = kmap(to);
  74         copy_page((void *)vto, (void *)vfrom);
  75         kunmap(from);
  76         kunmap(to);
  77 }
  78
  79 #endif /* _LINUX_HIGHMEM_H */