include/linux/highmem.h

   1 #ifndef _LINUX_HIGHMEM_H
   2 #define _LINUX_HIGHMEM_H
   3
   4 #include <linux/config.h>
   5 #include <linux/fs.h>
   6 #include <linux/mm.h>
   7
   8 #include <asm/cacheflush.h>
   9
  10 #ifdef CONFIG_HIGHMEM
  11
  12 extern struct page *highmem_start_page;
  13
  14 #include <asm/highmem.h>
  15
  16 /* declarations for linux/mm/highmem.c */
  17 unsigned int nr_free_highpages(void);
  18
  19 #else /* CONFIG_HIGHMEM */
  20
  21 static inline unsigned int nr_free_highpages(void) { return 0; }
  22
  23 static inline void *kmap(struct page *page)
  24 {
  25         might_sleep();
  26         return page_address(page);
  27 }
  28
  29 #define kunmap(page) do { (void) (page); } while (0)
  30
  31 #define kmap_atomic(page, idx)          page_address(page)
  32 #define kunmap_atomic(addr, idx)        do { } while (0)
  33 #define kmap_atomic_to_page(ptr)        virt_to_page(ptr)
  34
  35 #endif /* CONFIG_HIGHMEM */
  36
  37 /* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
  38 static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
  39 {
  40         void *addr = kmap_atomic(page, KM_USER0);
  41         clear_user_page(addr, vaddr, page);
  42         kunmap_atomic(addr, KM_USER0);
  43         /* Make sure this page is cleared on other CPU's too before using it */
  44         smp_wmb();
  45 }
  46
  47 static inline void clear_highpage(struct page *page)
  48 {
  49         void *kaddr = kmap_atomic(page, KM_USER0);
  50         clear_page(kaddr);
  51         kunmap_atomic(kaddr, KM_USER0);
  52 }
  53
  54 /*
  55  * Same but also flushes aliased cache contents to RAM.
  56  */
  57 static inline void memclear_highpage_flush(struct page *page, unsigned int offset, unsigned int size)
  58 {
  59         void *kaddr;
  60
  61         BUG_ON(offset + size > PAGE_SIZE);
  62
  63         kaddr = kmap_atomic(page, KM_USER0);
  64         memset((char *)kaddr + offset, 0, size);
  65         flush_dcache_page(page);
  66         kunmap_atomic(kaddr, KM_USER0);
  67 }
  68
  69 static inline void copy_user_highpage(struct page *to, struct page *from, unsigned long vaddr)
  70 {
  71         char *vfrom, *vto;
  72
  73         vfrom = kmap_atomic(from, KM_USER0);
  74         vto = kmap_atomic(to, KM_USER1);
  75         copy_user_page(vto, vfrom, vaddr, to);
  76         kunmap_atomic(vfrom, KM_USER0);
  77         kunmap_atomic(vto, KM_USER1);
  78         /* Make sure this page is cleared on other CPU's too before using it */
  79         smp_wmb();
  80 }
  81
  82 static inline void copy_highpage(struct page *to, struct page *from)
  83 {
  84         char *vfrom, *vto;
  85
  86         vfrom = kmap_atomic(from, KM_USER0);
  87         vto = kmap_atomic(to, KM_USER1);
  88         copy_page(vto, vfrom);
  89         kunmap_atomic(vfrom, KM_USER0);
  90         kunmap_atomic(vto, KM_USER1);
  91 }
  92
  93 #endif /* _LINUX_HIGHMEM_H */