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 */ 27struct 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 */ 73struct 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 84enum 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 95static inline void get_anon_vma(struct anon_vma *anon_vma) 96{ 97 atomic_inc(&anon_vma->refcount); 98} 99 100void __put_anon_vma(struct anon_vma *anon_vma); 101 102static 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 108static inline void anon_vma_lock_write(struct anon_vma *anon_vma) 109{ 110 down_write(&anon_vma->root->rwsem); 111} 112 113static inline void anon_vma_unlock_write(struct anon_vma *anon_vma) 114{ 115 up_write(&anon_vma->root->rwsem); 116} 117 118static inline void anon_vma_lock_read(struct anon_vma *anon_vma) 119{ 120 down_read(&anon_vma->root->rwsem); 121} 122 123static 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 */ 132void anon_vma_init(void); /* create anon_vma_cachep */ 133int anon_vma_prepare(struct vm_area_struct *); 134void unlink_anon_vmas(struct vm_area_struct *); 135int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); 136int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); 137 138static 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 145struct anon_vma *page_get_anon_vma(struct page *page); 146 147/* 148 * rmap interfaces called when adding or removing pte of page 149 */ 150void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 151void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 152void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, 153 unsigned long, int); 154void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); 155void page_add_file_rmap(struct page *); 156void page_remove_rmap(struct page *); 157 158void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, 159 unsigned long); 160void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, 161 unsigned long); 162 163static 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 */ 171int 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 176int try_to_unmap(struct page *, enum ttu_flags flags); 177 178/* 179 * Used by uprobes to replace a userspace page safely 180 */ 181pte_t *__page_check_address(struct page *, struct mm_struct *, 182 unsigned long, spinlock_t **, int); 183 184static 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 */ 198unsigned 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 */ 206int page_mkclean(struct page *); 207 208/* 209 * called in munlock()/munmap() path to check for other vmas holding 210 * the page mlocked. 211 */ 212int try_to_munlock(struct page *); 213 214/* 215 * Called by memory-failure.c to kill processes. 216 */ 217struct anon_vma *page_lock_anon_vma_read(struct page *page); 218void page_unlock_anon_vma_read(struct anon_vma *anon_vma); 219int 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 */ 230struct 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 239int 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 247static 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 257static 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