include/linux/highmem.h

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