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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 | ||
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 | |
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 | ||
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 | ||
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 | ||
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 | ||
125 | static inline void anon_vma_lock_write(struct anon_vma *anon_vma) | |
126 | { | |
127 | down_write(&anon_vma->root->rwsem); | |
128 | } | |
129 | ||
130 | static inline void anon_vma_unlock_write(struct anon_vma *anon_vma) | |
131 | { | |
132 | up_write(&anon_vma->root->rwsem); | |
133 | } | |
134 | ||
135 | static inline void anon_vma_lock_read(struct anon_vma *anon_vma) | |
136 | { | |
137 | down_read(&anon_vma->root->rwsem); | |
138 | } | |
139 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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 */ |