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TOMOYO Linux Cross Reference
Linux/include/linux/rmap.h

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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         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
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 
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 
115 static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
116 {
117         down_write(&anon_vma->root->rwsem);
118 }
119 
120 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
121 {
122         up_write(&anon_vma->root->rwsem);
123 }
124 
125 static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
126 {
127         down_read(&anon_vma->root->rwsem);
128 }
129 
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 
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 
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 
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
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 
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 
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 

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