#ifndef _LINUX_HIGHMEM_H
  #define _LINUX_HIGHMEM_H

  #include <linux/fs.h>

  #include <linux/kernel.h>

  #include <linux/mm.h>

  #include <linux/uaccess.h>

  
  #include <asm/cacheflush.h>

  #ifndef ARCH_HAS_FLUSH_ANON_PAGE

  static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)

  {
  }
  #endif

  #ifndef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
  static inline void flush_kernel_dcache_page(struct page *page)
  {
  }

  static inline void flush_kernel_vmap_range(void *vaddr, int size)
  {
  }
  static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
  {
  }

  #endif

  #include <asm/kmap_types.h>

  #ifdef CONFIG_DEBUG_HIGHMEM

  
  void debug_kmap_atomic(enum km_type type);
  
  #else

  static inline void debug_kmap_atomic(enum km_type type)
  {
  }
  
  #endif
  
  #ifdef CONFIG_HIGHMEM

  #include <asm/highmem.h>
  
  /* declarations for linux/mm/highmem.c */
  unsigned int nr_free_highpages(void);

  extern unsigned long totalhigh_pages;

  void kmap_flush_unused(void);

  #else /* CONFIG_HIGHMEM */
  
  static inline unsigned int nr_free_highpages(void) { return 0; }

  #define totalhigh_pages 0UL

  #ifndef ARCH_HAS_KMAP

  static inline void *kmap(struct page *page)
  {
  	might_sleep();
  	return page_address(page);
  }

  static inline void kunmap(struct page *page)
  {
  }

  static inline void *kmap_atomic(struct page *page, enum km_type idx)
  {
  	pagefault_disable();
  	return page_address(page);
  }

  #define kmap_atomic_prot(page, idx, prot)	kmap_atomic(page, idx)

  static inline void kunmap_atomic_notypecheck(void *addr, enum km_type idx)
  {
  	pagefault_enable();
  }

  #define kmap_atomic_pfn(pfn, idx)	kmap_atomic(pfn_to_page(pfn), (idx))

  #define kmap_atomic_to_page(ptr)	virt_to_page(ptr)

  
  #define kmap_flush_unused()	do {} while(0)

  #endif

  
  #endif /* CONFIG_HIGHMEM */

  /* Prevent people trying to call kunmap_atomic() as if it were kunmap() */
  /* kunmap_atomic() should get the return value of kmap_atomic, not the page. */
  #define kunmap_atomic(addr, idx) do { \
  		BUILD_BUG_ON(__same_type((addr), struct page *)); \
  		kunmap_atomic_notypecheck((addr), (idx)); \
  	} while (0)

  /* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */

  #ifndef clear_user_highpage

  static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
  {
  	void *addr = kmap_atomic(page, KM_USER0);
  	clear_user_page(addr, vaddr, page);
  	kunmap_atomic(addr, KM_USER0);

  }

  #endif

  
  #ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE

  /**
   * __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags
   * @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE
   * @vma: The VMA the page is to be allocated for
   * @vaddr: The virtual address the page will be inserted into
   *
   * This function will allocate a page for a VMA but the caller is expected
   * to specify via movableflags whether the page will be movable in the
   * future or not
   *
   * An architecture may override this function by defining
   * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own
   * implementation.
   */

  static inline struct page *

  __alloc_zeroed_user_highpage(gfp_t movableflags,
  			struct vm_area_struct *vma,
  			unsigned long vaddr)

  {

  	struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags,
  			vma, vaddr);

  
  	if (page)
  		clear_user_highpage(page, vaddr);
  
  	return page;
  }
  #endif

  /**

   * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
   * @vma: The VMA the page is to be allocated for
   * @vaddr: The virtual address the page will be inserted into
   *
   * This function will allocate a page for a VMA that the caller knows will
   * be able to migrate in the future using move_pages() or reclaimed
   */
  static inline struct page *
  alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
  					unsigned long vaddr)
  {
  	return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
  }

  static inline void clear_highpage(struct page *page)
  {
  	void *kaddr = kmap_atomic(page, KM_USER0);
  	clear_page(kaddr);
  	kunmap_atomic(kaddr, KM_USER0);
  }

  static inline void zero_user_segments(struct page *page,
  	unsigned start1, unsigned end1,
  	unsigned start2, unsigned end2)
  {
  	void *kaddr = kmap_atomic(page, KM_USER0);
  
  	BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE);
  
  	if (end1 > start1)
  		memset(kaddr + start1, 0, end1 - start1);
  
  	if (end2 > start2)
  		memset(kaddr + start2, 0, end2 - start2);
  
  	kunmap_atomic(kaddr, KM_USER0);
  	flush_dcache_page(page);
  }
  
  static inline void zero_user_segment(struct page *page,
  	unsigned start, unsigned end)
  {
  	zero_user_segments(page, start, end, 0, 0);
  }
  
  static inline void zero_user(struct page *page,
  	unsigned start, unsigned size)
  {
  	zero_user_segments(page, start, start + size, 0, 0);
  }

  static inline void __deprecated memclear_highpage_flush(struct page *page,

  			unsigned int offset, unsigned int size)

  {

  	zero_user(page, offset, size);

  }

  #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE

  static inline void copy_user_highpage(struct page *to, struct page *from,
  	unsigned long vaddr, struct vm_area_struct *vma)

  {
  	char *vfrom, *vto;
  
  	vfrom = kmap_atomic(from, KM_USER0);
  	vto = kmap_atomic(to, KM_USER1);
  	copy_user_page(vto, vfrom, vaddr, to);
  	kunmap_atomic(vfrom, KM_USER0);
  	kunmap_atomic(vto, KM_USER1);

  }

  #endif

  static inline void copy_highpage(struct page *to, struct page *from)
  {
  	char *vfrom, *vto;
  
  	vfrom = kmap_atomic(from, KM_USER0);
  	vto = kmap_atomic(to, KM_USER1);
  	copy_page(vto, vfrom);
  	kunmap_atomic(vfrom, KM_USER0);
  	kunmap_atomic(vto, KM_USER1);
  }
  
  #endif /* _LINUX_HIGHMEM_H */