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 90 TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */ 91 TTU_IGNORE_ACCESS = (1 << 9), /* don't age */ 92 TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */ 93 TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible 94 * and caller guarantees they will 95 * do a final flush if necessary */ 96 }; 97 98 #ifdef CONFIG_MMU 99 static inline void get_anon_vma(struct anon_vma *anon_vma) 100 { 101 atomic_inc(&anon_vma->refcount); 102 } 103 104 void __put_anon_vma(struct anon_vma *anon_vma); 105 106 static inline void put_anon_vma(struct anon_vma *anon_vma) 107 { 108 if (atomic_dec_and_test(&anon_vma->refcount)) 109 __put_anon_vma(anon_vma); 110 } 111 112 static inline void vma_lock_anon_vma(struct vm_area_struct *vma) 113 { 114 struct anon_vma *anon_vma = vma->anon_vma; 115 if (anon_vma) 116 down_write(&anon_vma->root->rwsem); 117 } 118 119 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma) 120 { 121 struct anon_vma *anon_vma = vma->anon_vma; 122 if (anon_vma) 123 up_write(&anon_vma->root->rwsem); 124 } 125 126 static inline void anon_vma_lock_write(struct anon_vma *anon_vma) 127 { 128 down_write(&anon_vma->root->rwsem); 129 } 130 131 static inline void anon_vma_unlock_write(struct anon_vma *anon_vma) 132 { 133 up_write(&anon_vma->root->rwsem); 134 } 135 136 static inline void anon_vma_lock_read(struct anon_vma *anon_vma) 137 { 138 down_read(&anon_vma->root->rwsem); 139 } 140 141 static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) 142 { 143 up_read(&anon_vma->root->rwsem); 144 } 145 146 147 /* 148 * anon_vma helper functions. 149 */ 150 void anon_vma_init(void); /* create anon_vma_cachep */ 151 int anon_vma_prepare(struct vm_area_struct *); 152 void unlink_anon_vmas(struct vm_area_struct *); 153 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 154 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 155 156 static inline void anon_vma_merge(struct vm_area_struct *vma, 157 struct vm_area_struct *next) 158 { 159 VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma); 160 unlink_anon_vmas(next); 161 } 162 163 struct anon_vma *page_get_anon_vma(struct page *page); 164 165 /* bitflags for do_page_add_anon_rmap() */ 166 #define RMAP_EXCLUSIVE 0x01 167 #define RMAP_COMPOUND 0x02 168 169 /* 170 * rmap interfaces called when adding or removing pte of page 171 */ 172 void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 173 void page_add_anon_rmap(struct page *, struct vm_area_struct *, 174 unsigned long, bool); 175 void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, 176 unsigned long, int); 177 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, 178 unsigned long, bool); 179 void page_add_file_rmap(struct page *); 180 void page_remove_rmap(struct page *, bool); 181 182 void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, 183 unsigned long); 184 void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, 185 unsigned long); 186 187 static inline void page_dup_rmap(struct page *page, bool compound) 188 { 189 atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount); 190 } 191 192 /* 193 * Called from mm/vmscan.c to handle paging out 194 */ 195 int page_referenced(struct page *, int is_locked, 196 struct mem_cgroup *memcg, unsigned long *vm_flags); 197 198 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK) 199 200 int try_to_unmap(struct page *, enum ttu_flags flags); 201 202 /* 203 * Used by uprobes to replace a userspace page safely 204 */ 205 pte_t *__page_check_address(struct page *, struct mm_struct *, 206 unsigned long, spinlock_t **, int); 207 208 static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm, 209 unsigned long address, 210 spinlock_t **ptlp, int sync) 211 { 212 pte_t *ptep; 213 214 __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address, 215 ptlp, sync)); 216 return ptep; 217 } 218 219 /* 220 * Used by idle page tracking to check if a page was referenced via page 221 * tables. 222 */ 223 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 224 bool page_check_address_transhuge(struct page *page, struct mm_struct *mm, 225 unsigned long address, pmd_t **pmdp, 226 pte_t **ptep, spinlock_t **ptlp); 227 #else 228 static inline bool page_check_address_transhuge(struct page *page, 229 struct mm_struct *mm, unsigned long address, 230 pmd_t **pmdp, pte_t **ptep, spinlock_t **ptlp) 231 { 232 *ptep = page_check_address(page, mm, address, ptlp, 0); 233 *pmdp = NULL; 234 return !!*ptep; 235 } 236 #endif 237 238 /* 239 * Used by swapoff to help locate where page is expected in vma. 240 */ 241 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); 242 243 /* 244 * Cleans the PTEs of shared mappings. 245 * (and since clean PTEs should also be readonly, write protects them too) 246 * 247 * returns the number of cleaned PTEs. 248 */ 249 int page_mkclean(struct page *); 250 251 /* 252 * called in munlock()/munmap() path to check for other vmas holding 253 * the page mlocked. 254 */ 255 int try_to_munlock(struct page *); 256 257 /* 258 * Called by memory-failure.c to kill processes. 259 */ 260 struct anon_vma *page_lock_anon_vma_read(struct page *page); 261 void page_unlock_anon_vma_read(struct anon_vma *anon_vma); 262 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); 263 264 /* 265 * rmap_walk_control: To control rmap traversing for specific needs 266 * 267 * arg: passed to rmap_one() and invalid_vma() 268 * rmap_one: executed on each vma where page is mapped 269 * done: for checking traversing termination condition 270 * anon_lock: for getting anon_lock by optimized way rather than default 271 * invalid_vma: for skipping uninterested vma 272 */ 273 struct rmap_walk_control { 274 void *arg; 275 int (*rmap_one)(struct page *page, struct vm_area_struct *vma, 276 unsigned long addr, void *arg); 277 int (*done)(struct page *page); 278 struct anon_vma *(*anon_lock)(struct page *page); 279 bool (*invalid_vma)(struct vm_area_struct *vma, void *arg); 280 }; 281 282 int rmap_walk(struct page *page, struct rmap_walk_control *rwc); 283 284 #else /* !CONFIG_MMU */ 285 286 #define anon_vma_init() do {} while (0) 287 #define anon_vma_prepare(vma) (0) 288 #define anon_vma_link(vma) do {} while (0) 289 290 static inline int page_referenced(struct page *page, int is_locked, 291 struct mem_cgroup *memcg, 292 unsigned long *vm_flags) 293 { 294 *vm_flags = 0; 295 return 0; 296 } 297 298 #define try_to_unmap(page, refs) SWAP_FAIL 299 300 static inline int page_mkclean(struct page *page) 301 { 302 return 0; 303 } 304 305 306 #endif /* CONFIG_MMU */ 307 308 /* 309 * Return values of try_to_unmap 310 */ 311 #define SWAP_SUCCESS 0 312 #define SWAP_AGAIN 1 313 #define SWAP_FAIL 2 314 #define SWAP_MLOCK 3 315 #define SWAP_LZFREE 4 316 317 #endif /* _LINUX_RMAP_H */ 318