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 TTU_LZFREE = 8, /* lazy free mode */
89 TTU_SPLIT_HUGE_PMD = 16, /* split huge PMD if any */
90
91 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
92 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
93 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
94 TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible
95 * and caller guarantees they will
96 * do a final flush if necessary */
97 TTU_RMAP_LOCKED = (1 << 12) /* do not grab rmap lock:
98 * caller holds it */
99 };
100
101 #ifdef CONFIG_MMU
get_anon_vma(struct anon_vma * anon_vma)102 static inline void get_anon_vma(struct anon_vma *anon_vma)
103 {
104 atomic_inc(&anon_vma->refcount);
105 }
106
107 void __put_anon_vma(struct anon_vma *anon_vma);
108
put_anon_vma(struct anon_vma * anon_vma)109 static inline void put_anon_vma(struct anon_vma *anon_vma)
110 {
111 if (atomic_dec_and_test(&anon_vma->refcount))
112 __put_anon_vma(anon_vma);
113 }
114
anon_vma_lock_write(struct anon_vma * anon_vma)115 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
116 {
117 down_write(&anon_vma->root->rwsem);
118 }
119
anon_vma_unlock_write(struct anon_vma * anon_vma)120 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
121 {
122 up_write(&anon_vma->root->rwsem);
123 }
124
anon_vma_lock_read(struct anon_vma * anon_vma)125 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
126 {
127 down_read(&anon_vma->root->rwsem);
128 }
129
anon_vma_unlock_read(struct anon_vma * anon_vma)130 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
131 {
132 up_read(&anon_vma->root->rwsem);
133 }
134
135
136 /*
137 * anon_vma helper functions.
138 */
139 void anon_vma_init(void); /* create anon_vma_cachep */
140 int anon_vma_prepare(struct vm_area_struct *);
141 void unlink_anon_vmas(struct vm_area_struct *);
142 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
143 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
144
anon_vma_merge(struct vm_area_struct * vma,struct vm_area_struct * next)145 static inline void anon_vma_merge(struct vm_area_struct *vma,
146 struct vm_area_struct *next)
147 {
148 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
149 unlink_anon_vmas(next);
150 }
151
152 struct anon_vma *page_get_anon_vma(struct page *page);
153
154 /* bitflags for do_page_add_anon_rmap() */
155 #define RMAP_EXCLUSIVE 0x01
156 #define RMAP_COMPOUND 0x02
157
158 /*
159 * rmap interfaces called when adding or removing pte of page
160 */
161 void page_move_anon_rmap(struct page *, struct vm_area_struct *);
162 void page_add_anon_rmap(struct page *, struct vm_area_struct *,
163 unsigned long, bool);
164 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
165 unsigned long, int);
166 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
167 unsigned long, bool);
168 void page_add_file_rmap(struct page *, bool);
169 void page_remove_rmap(struct page *, bool);
170
171 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
172 unsigned long);
173 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
174 unsigned long);
175
page_dup_rmap(struct page * page,bool compound)176 static inline void page_dup_rmap(struct page *page, bool compound)
177 {
178 atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount);
179 }
180
181 /*
182 * Called from mm/vmscan.c to handle paging out
183 */
184 int page_referenced(struct page *, int is_locked,
185 struct mem_cgroup *memcg, unsigned long *vm_flags);
186
187 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
188
189 int try_to_unmap(struct page *, enum ttu_flags flags);
190
191 /*
192 * Used by uprobes to replace a userspace page safely
193 */
194 pte_t *__page_check_address(struct page *, struct mm_struct *,
195 unsigned long, spinlock_t **, int);
196
page_check_address(struct page * page,struct mm_struct * mm,unsigned long address,spinlock_t ** ptlp,int sync)197 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
198 unsigned long address,
199 spinlock_t **ptlp, int sync)
200 {
201 pte_t *ptep;
202
203 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
204 ptlp, sync));
205 return ptep;
206 }
207
208 /*
209 * Used by idle page tracking to check if a page was referenced via page
210 * tables.
211 */
212 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
213 bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
214 unsigned long address, pmd_t **pmdp,
215 pte_t **ptep, spinlock_t **ptlp);
216 #else
page_check_address_transhuge(struct page * page,struct mm_struct * mm,unsigned long address,pmd_t ** pmdp,pte_t ** ptep,spinlock_t ** ptlp)217 static inline bool page_check_address_transhuge(struct page *page,
218 struct mm_struct *mm, unsigned long address,
219 pmd_t **pmdp, pte_t **ptep, spinlock_t **ptlp)
220 {
221 *ptep = page_check_address(page, mm, address, ptlp, 0);
222 *pmdp = NULL;
223 return !!*ptep;
224 }
225 #endif
226
227 /*
228 * Used by swapoff to help locate where page is expected in vma.
229 */
230 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
231
232 /*
233 * Cleans the PTEs of shared mappings.
234 * (and since clean PTEs should also be readonly, write protects them too)
235 *
236 * returns the number of cleaned PTEs.
237 */
238 int page_mkclean(struct page *);
239
240 /*
241 * called in munlock()/munmap() path to check for other vmas holding
242 * the page mlocked.
243 */
244 int try_to_munlock(struct page *);
245
246 void remove_migration_ptes(struct page *old, struct page *new, bool locked);
247
248 /*
249 * Called by memory-failure.c to kill processes.
250 */
251 struct anon_vma *page_lock_anon_vma_read(struct page *page);
252 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
253 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
254
255 /*
256 * rmap_walk_control: To control rmap traversing for specific needs
257 *
258 * arg: passed to rmap_one() and invalid_vma()
259 * rmap_one: executed on each vma where page is mapped
260 * done: for checking traversing termination condition
261 * anon_lock: for getting anon_lock by optimized way rather than default
262 * invalid_vma: for skipping uninterested vma
263 */
264 struct rmap_walk_control {
265 void *arg;
266 int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
267 unsigned long addr, void *arg);
268 int (*done)(struct page *page);
269 struct anon_vma *(*anon_lock)(struct page *page);
270 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
271 };
272
273 int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
274 int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
275
276 #else /* !CONFIG_MMU */
277
278 #define anon_vma_init() do {} while (0)
279 #define anon_vma_prepare(vma) (0)
280 #define anon_vma_link(vma) do {} while (0)
281
page_referenced(struct page * page,int is_locked,struct mem_cgroup * memcg,unsigned long * vm_flags)282 static inline int page_referenced(struct page *page, int is_locked,
283 struct mem_cgroup *memcg,
284 unsigned long *vm_flags)
285 {
286 *vm_flags = 0;
287 return 0;
288 }
289
290 #define try_to_unmap(page, refs) SWAP_FAIL
291
page_mkclean(struct page * page)292 static inline int page_mkclean(struct page *page)
293 {
294 return 0;
295 }
296
297
298 #endif /* CONFIG_MMU */
299
300 /*
301 * Return values of try_to_unmap
302 */
303 #define SWAP_SUCCESS 0
304 #define SWAP_AGAIN 1
305 #define SWAP_FAIL 2
306 #define SWAP_MLOCK 3
307 #define SWAP_LZFREE 4
308
309 #endif /* _LINUX_RMAP_H */
310