1 #ifndef _LINUX_RMAP_H
2 #define _LINUX_RMAP_H
3 /*
4 * Declarations for Reverse Mapping functions in mm/rmap.c
5 */
6
7 #include <linux/list.h>
8 #include <linux/slab.h>
9 #include <linux/mm.h>
10 #include <linux/rwsem.h>
11 #include <linux/memcontrol.h>
12
13 /*
14 * The anon_vma heads a list of private "related" vmas, to scan if
15 * an anonymous page pointing to this anon_vma needs to be unmapped:
16 * the vmas on the list will be related by forking, or by splitting.
17 *
18 * Since vmas come and go as they are split and merged (particularly
19 * in mprotect), the mapping field of an anonymous page cannot point
20 * directly to a vma: instead it points to an anon_vma, on whose list
21 * the related vmas can be easily linked or unlinked.
22 *
23 * After unlinking the last vma on the list, we must garbage collect
24 * the anon_vma object itself: we're guaranteed no page can be
25 * pointing to this anon_vma once its vma list is empty.
26 */
27 struct anon_vma {
28 struct anon_vma *root; /* Root of this anon_vma tree */
29 struct rw_semaphore rwsem; /* W: modification, R: walking the list */
30 /*
31 * The refcount is taken on an anon_vma when there is no
32 * guarantee that the vma of page tables will exist for
33 * the duration of the operation. A caller that takes
34 * the reference is responsible for clearing up the
35 * anon_vma if they are the last user on release
36 */
37 atomic_t refcount;
38
39 /*
40 * Count of child anon_vmas and VMAs which points to this anon_vma.
41 *
42 * This counter is used for making decision about reusing anon_vma
43 * instead of forking new one. See comments in function anon_vma_clone.
44 */
45 unsigned degree;
46
47 struct anon_vma *parent; /* Parent of this anon_vma */
48
49 /*
50 * NOTE: the LSB of the rb_root.rb_node is set by
51 * mm_take_all_locks() _after_ taking the above lock. So the
52 * rb_root must only be read/written after taking the above lock
53 * to be sure to see a valid next pointer. The LSB bit itself
54 * is serialized by a system wide lock only visible to
55 * mm_take_all_locks() (mm_all_locks_mutex).
56 */
57 struct rb_root rb_root; /* Interval tree of private "related" vmas */
58 };
59
60 /*
61 * The copy-on-write semantics of fork mean that an anon_vma
62 * can become associated with multiple processes. Furthermore,
63 * each child process will have its own anon_vma, where new
64 * pages for that process are instantiated.
65 *
66 * This structure allows us to find the anon_vmas associated
67 * with a VMA, or the VMAs associated with an anon_vma.
68 * The "same_vma" list contains the anon_vma_chains linking
69 * all the anon_vmas associated with this VMA.
70 * The "rb" field indexes on an interval tree the anon_vma_chains
71 * which link all the VMAs associated with this anon_vma.
72 */
73 struct anon_vma_chain {
74 struct vm_area_struct *vma;
75 struct anon_vma *anon_vma;
76 struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
77 struct rb_node rb; /* locked by anon_vma->rwsem */
78 unsigned long rb_subtree_last;
79 #ifdef CONFIG_DEBUG_VM_RB
80 unsigned long cached_vma_start, cached_vma_last;
81 #endif
82 };
83
84 enum ttu_flags {
85 TTU_UNMAP = 1, /* unmap mode */
86 TTU_MIGRATION = 2, /* migration mode */
87 TTU_MUNLOCK = 4, /* munlock mode */
88
89 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
90 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
91 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
92 TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible
93 * and caller guarantees they will
94 * do a final flush if necessary */
95 };
96
97 #ifdef CONFIG_MMU
get_anon_vma(struct anon_vma * anon_vma)98 static inline void get_anon_vma(struct anon_vma *anon_vma)
99 {
100 atomic_inc(&anon_vma->refcount);
101 }
102
103 void __put_anon_vma(struct anon_vma *anon_vma);
104
put_anon_vma(struct anon_vma * anon_vma)105 static inline void put_anon_vma(struct anon_vma *anon_vma)
106 {
107 if (atomic_dec_and_test(&anon_vma->refcount))
108 __put_anon_vma(anon_vma);
109 }
110
vma_lock_anon_vma(struct vm_area_struct * vma)111 static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
112 {
113 struct anon_vma *anon_vma = vma->anon_vma;
114 if (anon_vma)
115 down_write(&anon_vma->root->rwsem);
116 }
117
vma_unlock_anon_vma(struct vm_area_struct * vma)118 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
119 {
120 struct anon_vma *anon_vma = vma->anon_vma;
121 if (anon_vma)
122 up_write(&anon_vma->root->rwsem);
123 }
124
anon_vma_lock_write(struct anon_vma * anon_vma)125 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
126 {
127 down_write(&anon_vma->root->rwsem);
128 }
129
anon_vma_unlock_write(struct anon_vma * anon_vma)130 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
131 {
132 up_write(&anon_vma->root->rwsem);
133 }
134
anon_vma_lock_read(struct anon_vma * anon_vma)135 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
136 {
137 down_read(&anon_vma->root->rwsem);
138 }
139
anon_vma_unlock_read(struct anon_vma * anon_vma)140 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
141 {
142 up_read(&anon_vma->root->rwsem);
143 }
144
145
146 /*
147 * anon_vma helper functions.
148 */
149 void anon_vma_init(void); /* create anon_vma_cachep */
150 int anon_vma_prepare(struct vm_area_struct *);
151 void unlink_anon_vmas(struct vm_area_struct *);
152 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
153 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
154
anon_vma_merge(struct vm_area_struct * vma,struct vm_area_struct * next)155 static inline void anon_vma_merge(struct vm_area_struct *vma,
156 struct vm_area_struct *next)
157 {
158 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
159 unlink_anon_vmas(next);
160 }
161
162 struct anon_vma *page_get_anon_vma(struct page *page);
163
164 /*
165 * rmap interfaces called when adding or removing pte of page
166 */
167 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
168 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
169 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
170 unsigned long, int);
171 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
172 void page_add_file_rmap(struct page *);
173 void page_remove_rmap(struct page *);
174
175 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
176 unsigned long);
177 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
178 unsigned long);
179
page_dup_rmap(struct page * page)180 static inline void page_dup_rmap(struct page *page)
181 {
182 atomic_inc(&page->_mapcount);
183 }
184
185 /*
186 * Called from mm/vmscan.c to handle paging out
187 */
188 int page_referenced(struct page *, int is_locked,
189 struct mem_cgroup *memcg, unsigned long *vm_flags);
190
191 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
192
193 int try_to_unmap(struct page *, enum ttu_flags flags);
194
195 /*
196 * Used by uprobes to replace a userspace page safely
197 */
198 pte_t *__page_check_address(struct page *, struct mm_struct *,
199 unsigned long, spinlock_t **, int);
200
page_check_address(struct page * page,struct mm_struct * mm,unsigned long address,spinlock_t ** ptlp,int sync)201 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
202 unsigned long address,
203 spinlock_t **ptlp, int sync)
204 {
205 pte_t *ptep;
206
207 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
208 ptlp, sync));
209 return ptep;
210 }
211
212 /*
213 * Used by swapoff to help locate where page is expected in vma.
214 */
215 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
216
217 /*
218 * Cleans the PTEs of shared mappings.
219 * (and since clean PTEs should also be readonly, write protects them too)
220 *
221 * returns the number of cleaned PTEs.
222 */
223 int page_mkclean(struct page *);
224
225 /*
226 * called in munlock()/munmap() path to check for other vmas holding
227 * the page mlocked.
228 */
229 int try_to_munlock(struct page *);
230
231 /*
232 * Called by memory-failure.c to kill processes.
233 */
234 struct anon_vma *page_lock_anon_vma_read(struct page *page);
235 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
236 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
237
238 /*
239 * rmap_walk_control: To control rmap traversing for specific needs
240 *
241 * arg: passed to rmap_one() and invalid_vma()
242 * rmap_one: executed on each vma where page is mapped
243 * done: for checking traversing termination condition
244 * anon_lock: for getting anon_lock by optimized way rather than default
245 * invalid_vma: for skipping uninterested vma
246 */
247 struct rmap_walk_control {
248 void *arg;
249 int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
250 unsigned long addr, void *arg);
251 int (*done)(struct page *page);
252 struct anon_vma *(*anon_lock)(struct page *page);
253 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
254 };
255
256 int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
257
258 #else /* !CONFIG_MMU */
259
260 #define anon_vma_init() do {} while (0)
261 #define anon_vma_prepare(vma) (0)
262 #define anon_vma_link(vma) do {} while (0)
263
page_referenced(struct page * page,int is_locked,struct mem_cgroup * memcg,unsigned long * vm_flags)264 static inline int page_referenced(struct page *page, int is_locked,
265 struct mem_cgroup *memcg,
266 unsigned long *vm_flags)
267 {
268 *vm_flags = 0;
269 return 0;
270 }
271
272 #define try_to_unmap(page, refs) SWAP_FAIL
273
page_mkclean(struct page * page)274 static inline int page_mkclean(struct page *page)
275 {
276 return 0;
277 }
278
279
280 #endif /* CONFIG_MMU */
281
282 /*
283 * Return values of try_to_unmap
284 */
285 #define SWAP_SUCCESS 0
286 #define SWAP_AGAIN 1
287 #define SWAP_FAIL 2
288 #define SWAP_MLOCK 3
289
290 #endif /* _LINUX_RMAP_H */
291