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
anon_vma_lock_write(struct anon_vma * anon_vma)111 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
112 {
113 down_write(&anon_vma->root->rwsem);
114 }
115
anon_vma_unlock_write(struct anon_vma * anon_vma)116 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
117 {
118 up_write(&anon_vma->root->rwsem);
119 }
120
anon_vma_lock_read(struct anon_vma * anon_vma)121 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
122 {
123 down_read(&anon_vma->root->rwsem);
124 }
125
anon_vma_unlock_read(struct anon_vma * anon_vma)126 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
127 {
128 up_read(&anon_vma->root->rwsem);
129 }
130
131
132 /*
133 * anon_vma helper functions.
134 */
135 void anon_vma_init(void); /* create anon_vma_cachep */
136 int anon_vma_prepare(struct vm_area_struct *);
137 void unlink_anon_vmas(struct vm_area_struct *);
138 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
139 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
140
anon_vma_merge(struct vm_area_struct * vma,struct vm_area_struct * next)141 static inline void anon_vma_merge(struct vm_area_struct *vma,
142 struct vm_area_struct *next)
143 {
144 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
145 unlink_anon_vmas(next);
146 }
147
148 struct anon_vma *page_get_anon_vma(struct page *page);
149
150 /*
151 * rmap interfaces called when adding or removing pte of page
152 */
153 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
154 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
155 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
156 unsigned long, int);
157 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
158 void page_add_file_rmap(struct page *);
159 void page_remove_rmap(struct page *);
160
161 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
162 unsigned long);
163 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
164 unsigned long);
165
page_dup_rmap(struct page * page)166 static inline void page_dup_rmap(struct page *page)
167 {
168 atomic_inc(&page->_mapcount);
169 }
170
171 /*
172 * Called from mm/vmscan.c to handle paging out
173 */
174 int page_referenced(struct page *, int is_locked,
175 struct mem_cgroup *memcg, unsigned long *vm_flags);
176
177 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
178
179 int try_to_unmap(struct page *, enum ttu_flags flags);
180
181 /*
182 * Used by uprobes to replace a userspace page safely
183 */
184 pte_t *__page_check_address(struct page *, struct mm_struct *,
185 unsigned long, spinlock_t **, int);
186
page_check_address(struct page * page,struct mm_struct * mm,unsigned long address,spinlock_t ** ptlp,int sync)187 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
188 unsigned long address,
189 spinlock_t **ptlp, int sync)
190 {
191 pte_t *ptep;
192
193 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
194 ptlp, sync));
195 return ptep;
196 }
197
198 /*
199 * Used by swapoff to help locate where page is expected in vma.
200 */
201 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
202
203 /*
204 * Cleans the PTEs of shared mappings.
205 * (and since clean PTEs should also be readonly, write protects them too)
206 *
207 * returns the number of cleaned PTEs.
208 */
209 int page_mkclean(struct page *);
210
211 /*
212 * called in munlock()/munmap() path to check for other vmas holding
213 * the page mlocked.
214 */
215 int try_to_munlock(struct page *);
216
217 /*
218 * Called by memory-failure.c to kill processes.
219 */
220 struct anon_vma *page_lock_anon_vma_read(struct page *page);
221 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
222 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
223
224 /*
225 * rmap_walk_control: To control rmap traversing for specific needs
226 *
227 * arg: passed to rmap_one() and invalid_vma()
228 * rmap_one: executed on each vma where page is mapped
229 * done: for checking traversing termination condition
230 * anon_lock: for getting anon_lock by optimized way rather than default
231 * invalid_vma: for skipping uninterested vma
232 */
233 struct rmap_walk_control {
234 void *arg;
235 int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
236 unsigned long addr, void *arg);
237 int (*done)(struct page *page);
238 struct anon_vma *(*anon_lock)(struct page *page);
239 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
240 };
241
242 int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
243
244 #else /* !CONFIG_MMU */
245
246 #define anon_vma_init() do {} while (0)
247 #define anon_vma_prepare(vma) (0)
248 #define anon_vma_link(vma) do {} while (0)
249
page_referenced(struct page * page,int is_locked,struct mem_cgroup * memcg,unsigned long * vm_flags)250 static inline int page_referenced(struct page *page, int is_locked,
251 struct mem_cgroup *memcg,
252 unsigned long *vm_flags)
253 {
254 *vm_flags = 0;
255 return 0;
256 }
257
258 #define try_to_unmap(page, refs) SWAP_FAIL
259
page_mkclean(struct page * page)260 static inline int page_mkclean(struct page *page)
261 {
262 return 0;
263 }
264
265
266 #endif /* CONFIG_MMU */
267
268 /*
269 * Return values of try_to_unmap
270 */
271 #define SWAP_SUCCESS 0
272 #define SWAP_AGAIN 1
273 #define SWAP_FAIL 2
274 #define SWAP_MLOCK 3
275
276 #endif /* _LINUX_RMAP_H */
277