rmap.h 3.7 KB

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  1. #ifndef _LINUX_RMAP_H
  2. #define _LINUX_RMAP_H
  3. /*
  4. * Declarations for Reverse Mapping functions in mm/rmap.c
  5. */
  6. #include <linux/list.h>
  7. #include <linux/slab.h>
  8. #include <linux/mm.h>
  9. #include <linux/spinlock.h>
  10. /*
  11. * The anon_vma heads a list of private "related" vmas, to scan if
  12. * an anonymous page pointing to this anon_vma needs to be unmapped:
  13. * the vmas on the list will be related by forking, or by splitting.
  14. *
  15. * Since vmas come and go as they are split and merged (particularly
  16. * in mprotect), the mapping field of an anonymous page cannot point
  17. * directly to a vma: instead it points to an anon_vma, on whose list
  18. * the related vmas can be easily linked or unlinked.
  19. *
  20. * After unlinking the last vma on the list, we must garbage collect
  21. * the anon_vma object itself: we're guaranteed no page can be
  22. * pointing to this anon_vma once its vma list is empty.
  23. */
  24. struct anon_vma {
  25. spinlock_t lock; /* Serialize access to vma list */
  26. struct list_head head; /* List of private "related" vmas */
  27. };
  28. #ifdef CONFIG_MMU
  29. extern struct kmem_cache *anon_vma_cachep;
  30. static inline struct anon_vma *anon_vma_alloc(void)
  31. {
  32. return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
  33. }
  34. static inline void anon_vma_free(struct anon_vma *anon_vma)
  35. {
  36. kmem_cache_free(anon_vma_cachep, anon_vma);
  37. }
  38. static inline void anon_vma_lock(struct vm_area_struct *vma)
  39. {
  40. struct anon_vma *anon_vma = vma->anon_vma;
  41. if (anon_vma)
  42. spin_lock(&anon_vma->lock);
  43. }
  44. static inline void anon_vma_unlock(struct vm_area_struct *vma)
  45. {
  46. struct anon_vma *anon_vma = vma->anon_vma;
  47. if (anon_vma)
  48. spin_unlock(&anon_vma->lock);
  49. }
  50. /*
  51. * anon_vma helper functions.
  52. */
  53. void anon_vma_init(void); /* create anon_vma_cachep */
  54. int anon_vma_prepare(struct vm_area_struct *);
  55. void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
  56. void anon_vma_unlink(struct vm_area_struct *);
  57. void anon_vma_link(struct vm_area_struct *);
  58. void __anon_vma_link(struct vm_area_struct *);
  59. /*
  60. * rmap interfaces called when adding or removing pte of page
  61. */
  62. void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  63. void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
  64. void page_add_file_rmap(struct page *);
  65. void page_remove_rmap(struct page *, struct vm_area_struct *);
  66. /**
  67. * page_dup_rmap - duplicate pte mapping to a page
  68. * @page: the page to add the mapping to
  69. *
  70. * For copy_page_range only: minimal extract from page_add_rmap,
  71. * avoiding unnecessary tests (already checked) so it's quicker.
  72. */
  73. static inline void page_dup_rmap(struct page *page)
  74. {
  75. atomic_inc(&page->_mapcount);
  76. }
  77. /*
  78. * Called from mm/vmscan.c to handle paging out
  79. */
  80. int page_referenced(struct page *, int is_locked);
  81. int try_to_unmap(struct page *, int ignore_refs);
  82. /*
  83. * Called from mm/filemap_xip.c to unmap empty zero page
  84. */
  85. pte_t *page_check_address(struct page *, struct mm_struct *,
  86. unsigned long, spinlock_t **);
  87. /*
  88. * Used by swapoff to help locate where page is expected in vma.
  89. */
  90. unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
  91. /*
  92. * Cleans the PTEs of shared mappings.
  93. * (and since clean PTEs should also be readonly, write protects them too)
  94. *
  95. * returns the number of cleaned PTEs.
  96. */
  97. int page_mkclean(struct page *);
  98. #else /* !CONFIG_MMU */
  99. #define anon_vma_init() do {} while (0)
  100. #define anon_vma_prepare(vma) (0)
  101. #define anon_vma_link(vma) do {} while (0)
  102. #define page_referenced(page,l) TestClearPageReferenced(page)
  103. #define try_to_unmap(page, refs) SWAP_FAIL
  104. static inline int page_mkclean(struct page *page)
  105. {
  106. return 0;
  107. }
  108. #endif /* CONFIG_MMU */
  109. /*
  110. * Return values of try_to_unmap
  111. */
  112. #define SWAP_SUCCESS 0
  113. #define SWAP_AGAIN 1
  114. #define SWAP_FAIL 2
  115. #endif /* _LINUX_RMAP_H */