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 };
93
94 #ifdef CONFIG_MMU
get_anon_vma(struct anon_vma * anon_vma)95 static inline void get_anon_vma(struct anon_vma *anon_vma)
96 {
97 atomic_inc(&anon_vma->refcount);
98 }
99
100 void __put_anon_vma(struct anon_vma *anon_vma);
101
put_anon_vma(struct anon_vma * anon_vma)102 static inline void put_anon_vma(struct anon_vma *anon_vma)
103 {
104 if (atomic_dec_and_test(&anon_vma->refcount))
105 __put_anon_vma(anon_vma);
106 }
107
anon_vma_lock_write(struct anon_vma * anon_vma)108 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
109 {
110 down_write(&anon_vma->root->rwsem);
111 }
112
anon_vma_unlock_write(struct anon_vma * anon_vma)113 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
114 {
115 up_write(&anon_vma->root->rwsem);
116 }
117
anon_vma_lock_read(struct anon_vma * anon_vma)118 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
119 {
120 down_read(&anon_vma->root->rwsem);
121 }
122
anon_vma_unlock_read(struct anon_vma * anon_vma)123 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
124 {
125 up_read(&anon_vma->root->rwsem);
126 }
127
128
129 /*
130 * anon_vma helper functions.
131 */
132 void anon_vma_init(void); /* create anon_vma_cachep */
133 int anon_vma_prepare(struct vm_area_struct *);
134 void unlink_anon_vmas(struct vm_area_struct *);
135 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
136 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
137
anon_vma_merge(struct vm_area_struct * vma,struct vm_area_struct * next)138 static inline void anon_vma_merge(struct vm_area_struct *vma,
139 struct vm_area_struct *next)
140 {
141 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
142 unlink_anon_vmas(next);
143 }
144
145 struct anon_vma *page_get_anon_vma(struct page *page);
146
147 /*
148 * rmap interfaces called when adding or removing pte of page
149 */
150 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
151 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
152 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
153 unsigned long, int);
154 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
155 void page_add_file_rmap(struct page *);
156 void page_remove_rmap(struct page *);
157
158 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
159 unsigned long);
160 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
161 unsigned long);
162
page_dup_rmap(struct page * page)163 static inline void page_dup_rmap(struct page *page)
164 {
165 atomic_inc(&page->_mapcount);
166 }
167
168 /*
169 * Called from mm/vmscan.c to handle paging out
170 */
171 int page_referenced(struct page *, int is_locked,
172 struct mem_cgroup *memcg, unsigned long *vm_flags);
173
174 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
175
176 int try_to_unmap(struct page *, enum ttu_flags flags);
177
178 /*
179 * Used by uprobes to replace a userspace page safely
180 */
181 pte_t *__page_check_address(struct page *, struct mm_struct *,
182 unsigned long, spinlock_t **, int);
183
page_check_address(struct page * page,struct mm_struct * mm,unsigned long address,spinlock_t ** ptlp,int sync)184 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
185 unsigned long address,
186 spinlock_t **ptlp, int sync)
187 {
188 pte_t *ptep;
189
190 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
191 ptlp, sync));
192 return ptep;
193 }
194
195 /*
196 * Used by swapoff to help locate where page is expected in vma.
197 */
198 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
199
200 /*
201 * Cleans the PTEs of shared mappings.
202 * (and since clean PTEs should also be readonly, write protects them too)
203 *
204 * returns the number of cleaned PTEs.
205 */
206 int page_mkclean(struct page *);
207
208 /*
209 * called in munlock()/munmap() path to check for other vmas holding
210 * the page mlocked.
211 */
212 int try_to_munlock(struct page *);
213
214 /*
215 * Called by memory-failure.c to kill processes.
216 */
217 struct anon_vma *page_lock_anon_vma_read(struct page *page);
218 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
219 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
220
221 /*
222 * rmap_walk_control: To control rmap traversing for specific needs
223 *
224 * arg: passed to rmap_one() and invalid_vma()
225 * rmap_one: executed on each vma where page is mapped
226 * done: for checking traversing termination condition
227 * anon_lock: for getting anon_lock by optimized way rather than default
228 * invalid_vma: for skipping uninterested vma
229 */
230 struct rmap_walk_control {
231 void *arg;
232 int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
233 unsigned long addr, void *arg);
234 int (*done)(struct page *page);
235 struct anon_vma *(*anon_lock)(struct page *page);
236 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
237 };
238
239 int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
240
241 #else /* !CONFIG_MMU */
242
243 #define anon_vma_init() do {} while (0)
244 #define anon_vma_prepare(vma) (0)
245 #define anon_vma_link(vma) do {} while (0)
246
page_referenced(struct page * page,int is_locked,struct mem_cgroup * memcg,unsigned long * vm_flags)247 static inline int page_referenced(struct page *page, int is_locked,
248 struct mem_cgroup *memcg,
249 unsigned long *vm_flags)
250 {
251 *vm_flags = 0;
252 return 0;
253 }
254
255 #define try_to_unmap(page, refs) SWAP_FAIL
256
page_mkclean(struct page * page)257 static inline int page_mkclean(struct page *page)
258 {
259 return 0;
260 }
261
262
263 #endif /* CONFIG_MMU */
264
265 /*
266 * Return values of try_to_unmap
267 */
268 #define SWAP_SUCCESS 0
269 #define SWAP_AGAIN 1
270 #define SWAP_FAIL 2
271 #define SWAP_MLOCK 3
272
273 #endif /* _LINUX_RMAP_H */
274