1 #ifndef _LINUX_MMU_NOTIFIER_H 2 #define _LINUX_MMU_NOTIFIER_H 3 4 #include <linux/list.h> 5 #include <linux/spinlock.h> 6 #include <linux/mm_types.h> 7 8 struct mmu_notifier; 9 struct mmu_notifier_ops; 10 11 #ifdef CONFIG_MMU_NOTIFIER 12 13 /* 14 * The mmu notifier_mm structure is allocated and installed in 15 * mm->mmu_notifier_mm inside the mm_take_all_locks() protected 16 * critical section and it's released only when mm_count reaches zero 17 * in mmdrop(). 18 */ 19 struct mmu_notifier_mm { 20 /* all mmu notifiers registerd in this mm are queued in this list */ 21 struct hlist_head list; 22 /* to serialize the list modifications and hlist_unhashed */ 23 spinlock_t lock; 24 }; 25 26 struct mmu_notifier_ops { 27 /* 28 * Called either by mmu_notifier_unregister or when the mm is 29 * being destroyed by exit_mmap, always before all pages are 30 * freed. This can run concurrently with other mmu notifier 31 * methods (the ones invoked outside the mm context) and it 32 * should tear down all secondary mmu mappings and freeze the 33 * secondary mmu. If this method isn't implemented you've to 34 * be sure that nothing could possibly write to the pages 35 * through the secondary mmu by the time the last thread with 36 * tsk->mm == mm exits. 37 * 38 * As side note: the pages freed after ->release returns could 39 * be immediately reallocated by the gart at an alias physical 40 * address with a different cache model, so if ->release isn't 41 * implemented because all _software_ driven memory accesses 42 * through the secondary mmu are terminated by the time the 43 * last thread of this mm quits, you've also to be sure that 44 * speculative _hardware_ operations can't allocate dirty 45 * cachelines in the cpu that could not be snooped and made 46 * coherent with the other read and write operations happening 47 * through the gart alias address, so leading to memory 48 * corruption. 49 */ 50 void (*release)(struct mmu_notifier *mn, 51 struct mm_struct *mm); 52 53 /* 54 * clear_flush_young is called after the VM is 55 * test-and-clearing the young/accessed bitflag in the 56 * pte. This way the VM will provide proper aging to the 57 * accesses to the page through the secondary MMUs and not 58 * only to the ones through the Linux pte. 59 */ 60 int (*clear_flush_young)(struct mmu_notifier *mn, 61 struct mm_struct *mm, 62 unsigned long address); 63 64 /* 65 * test_young is called to check the young/accessed bitflag in 66 * the secondary pte. This is used to know if the page is 67 * frequently used without actually clearing the flag or tearing 68 * down the secondary mapping on the page. 69 */ 70 int (*test_young)(struct mmu_notifier *mn, 71 struct mm_struct *mm, 72 unsigned long address); 73 74 /* 75 * change_pte is called in cases that pte mapping to page is changed: 76 * for example, when ksm remaps pte to point to a new shared page. 77 */ 78 void (*change_pte)(struct mmu_notifier *mn, 79 struct mm_struct *mm, 80 unsigned long address, 81 pte_t pte); 82 83 /* 84 * Before this is invoked any secondary MMU is still ok to 85 * read/write to the page previously pointed to by the Linux 86 * pte because the page hasn't been freed yet and it won't be 87 * freed until this returns. If required set_page_dirty has to 88 * be called internally to this method. 89 */ 90 void (*invalidate_page)(struct mmu_notifier *mn, 91 struct mm_struct *mm, 92 unsigned long address); 93 94 /* 95 * invalidate_range_start() and invalidate_range_end() must be 96 * paired and are called only when the mmap_sem and/or the 97 * locks protecting the reverse maps are held. The subsystem 98 * must guarantee that no additional references are taken to 99 * the pages in the range established between the call to 100 * invalidate_range_start() and the matching call to 101 * invalidate_range_end(). 102 * 103 * Invalidation of multiple concurrent ranges may be 104 * optionally permitted by the driver. Either way the 105 * establishment of sptes is forbidden in the range passed to 106 * invalidate_range_begin/end for the whole duration of the 107 * invalidate_range_begin/end critical section. 108 * 109 * invalidate_range_start() is called when all pages in the 110 * range are still mapped and have at least a refcount of one. 111 * 112 * invalidate_range_end() is called when all pages in the 113 * range have been unmapped and the pages have been freed by 114 * the VM. 115 * 116 * The VM will remove the page table entries and potentially 117 * the page between invalidate_range_start() and 118 * invalidate_range_end(). If the page must not be freed 119 * because of pending I/O or other circumstances then the 120 * invalidate_range_start() callback (or the initial mapping 121 * by the driver) must make sure that the refcount is kept 122 * elevated. 123 * 124 * If the driver increases the refcount when the pages are 125 * initially mapped into an address space then either 126 * invalidate_range_start() or invalidate_range_end() may 127 * decrease the refcount. If the refcount is decreased on 128 * invalidate_range_start() then the VM can free pages as page 129 * table entries are removed. If the refcount is only 130 * droppped on invalidate_range_end() then the driver itself 131 * will drop the last refcount but it must take care to flush 132 * any secondary tlb before doing the final free on the 133 * page. Pages will no longer be referenced by the linux 134 * address space but may still be referenced by sptes until 135 * the last refcount is dropped. 136 */ 137 void (*invalidate_range_start)(struct mmu_notifier *mn, 138 struct mm_struct *mm, 139 unsigned long start, unsigned long end); 140 void (*invalidate_range_end)(struct mmu_notifier *mn, 141 struct mm_struct *mm, 142 unsigned long start, unsigned long end); 143 }; 144 145 /* 146 * The notifier chains are protected by mmap_sem and/or the reverse map 147 * semaphores. Notifier chains are only changed when all reverse maps and 148 * the mmap_sem locks are taken. 149 * 150 * Therefore notifier chains can only be traversed when either 151 * 152 * 1. mmap_sem is held. 153 * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->mutex). 154 * 3. No other concurrent thread can access the list (release) 155 */ 156 struct mmu_notifier { 157 struct hlist_node hlist; 158 const struct mmu_notifier_ops *ops; 159 }; 160 161 static inline int mm_has_notifiers(struct mm_struct *mm) 162 { 163 return unlikely(mm->mmu_notifier_mm); 164 } 165 166 extern int mmu_notifier_register(struct mmu_notifier *mn, 167 struct mm_struct *mm); 168 extern int __mmu_notifier_register(struct mmu_notifier *mn, 169 struct mm_struct *mm); 170 extern void mmu_notifier_unregister(struct mmu_notifier *mn, 171 struct mm_struct *mm); 172 extern void __mmu_notifier_mm_destroy(struct mm_struct *mm); 173 extern void __mmu_notifier_release(struct mm_struct *mm); 174 extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm, 175 unsigned long address); 176 extern int __mmu_notifier_test_young(struct mm_struct *mm, 177 unsigned long address); 178 extern void __mmu_notifier_change_pte(struct mm_struct *mm, 179 unsigned long address, pte_t pte); 180 extern void __mmu_notifier_invalidate_page(struct mm_struct *mm, 181 unsigned long address); 182 extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm, 183 unsigned long start, unsigned long end); 184 extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm, 185 unsigned long start, unsigned long end); 186 187 static inline void mmu_notifier_release(struct mm_struct *mm) 188 { 189 if (mm_has_notifiers(mm)) 190 __mmu_notifier_release(mm); 191 } 192 193 static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, 194 unsigned long address) 195 { 196 if (mm_has_notifiers(mm)) 197 return __mmu_notifier_clear_flush_young(mm, address); 198 return 0; 199 } 200 201 static inline int mmu_notifier_test_young(struct mm_struct *mm, 202 unsigned long address) 203 { 204 if (mm_has_notifiers(mm)) 205 return __mmu_notifier_test_young(mm, address); 206 return 0; 207 } 208 209 static inline void mmu_notifier_change_pte(struct mm_struct *mm, 210 unsigned long address, pte_t pte) 211 { 212 if (mm_has_notifiers(mm)) 213 __mmu_notifier_change_pte(mm, address, pte); 214 } 215 216 static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, 217 unsigned long address) 218 { 219 if (mm_has_notifiers(mm)) 220 __mmu_notifier_invalidate_page(mm, address); 221 } 222 223 static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, 224 unsigned long start, unsigned long end) 225 { 226 if (mm_has_notifiers(mm)) 227 __mmu_notifier_invalidate_range_start(mm, start, end); 228 } 229 230 static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, 231 unsigned long start, unsigned long end) 232 { 233 if (mm_has_notifiers(mm)) 234 __mmu_notifier_invalidate_range_end(mm, start, end); 235 } 236 237 static inline void mmu_notifier_mm_init(struct mm_struct *mm) 238 { 239 mm->mmu_notifier_mm = NULL; 240 } 241 242 static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) 243 { 244 if (mm_has_notifiers(mm)) 245 __mmu_notifier_mm_destroy(mm); 246 } 247 248 /* 249 * These two macros will sometime replace ptep_clear_flush. 250 * ptep_clear_flush is implemented as macro itself, so this also is 251 * implemented as a macro until ptep_clear_flush will converted to an 252 * inline function, to diminish the risk of compilation failure. The 253 * invalidate_page method over time can be moved outside the PT lock 254 * and these two macros can be later removed. 255 */ 256 #define ptep_clear_flush_notify(__vma, __address, __ptep) \ 257 ({ \ 258 pte_t __pte; \ 259 struct vm_area_struct *___vma = __vma; \ 260 unsigned long ___address = __address; \ 261 __pte = ptep_clear_flush(___vma, ___address, __ptep); \ 262 mmu_notifier_invalidate_page(___vma->vm_mm, ___address); \ 263 __pte; \ 264 }) 265 266 #define pmdp_clear_flush_notify(__vma, __address, __pmdp) \ 267 ({ \ 268 pmd_t __pmd; \ 269 struct vm_area_struct *___vma = __vma; \ 270 unsigned long ___address = __address; \ 271 VM_BUG_ON(__address & ~HPAGE_PMD_MASK); \ 272 mmu_notifier_invalidate_range_start(___vma->vm_mm, ___address, \ 273 (__address)+HPAGE_PMD_SIZE);\ 274 __pmd = pmdp_clear_flush(___vma, ___address, __pmdp); \ 275 mmu_notifier_invalidate_range_end(___vma->vm_mm, ___address, \ 276 (__address)+HPAGE_PMD_SIZE); \ 277 __pmd; \ 278 }) 279 280 #define pmdp_splitting_flush_notify(__vma, __address, __pmdp) \ 281 ({ \ 282 struct vm_area_struct *___vma = __vma; \ 283 unsigned long ___address = __address; \ 284 VM_BUG_ON(__address & ~HPAGE_PMD_MASK); \ 285 mmu_notifier_invalidate_range_start(___vma->vm_mm, ___address, \ 286 (__address)+HPAGE_PMD_SIZE);\ 287 pmdp_splitting_flush(___vma, ___address, __pmdp); \ 288 mmu_notifier_invalidate_range_end(___vma->vm_mm, ___address, \ 289 (__address)+HPAGE_PMD_SIZE); \ 290 }) 291 292 #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \ 293 ({ \ 294 int __young; \ 295 struct vm_area_struct *___vma = __vma; \ 296 unsigned long ___address = __address; \ 297 __young = ptep_clear_flush_young(___vma, ___address, __ptep); \ 298 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \ 299 ___address); \ 300 __young; \ 301 }) 302 303 #define pmdp_clear_flush_young_notify(__vma, __address, __pmdp) \ 304 ({ \ 305 int __young; \ 306 struct vm_area_struct *___vma = __vma; \ 307 unsigned long ___address = __address; \ 308 __young = pmdp_clear_flush_young(___vma, ___address, __pmdp); \ 309 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \ 310 ___address); \ 311 __young; \ 312 }) 313 314 #define set_pte_at_notify(__mm, __address, __ptep, __pte) \ 315 ({ \ 316 struct mm_struct *___mm = __mm; \ 317 unsigned long ___address = __address; \ 318 pte_t ___pte = __pte; \ 319 \ 320 set_pte_at(___mm, ___address, __ptep, ___pte); \ 321 mmu_notifier_change_pte(___mm, ___address, ___pte); \ 322 }) 323 324 #else /* CONFIG_MMU_NOTIFIER */ 325 326 static inline void mmu_notifier_release(struct mm_struct *mm) 327 { 328 } 329 330 static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, 331 unsigned long address) 332 { 333 return 0; 334 } 335 336 static inline int mmu_notifier_test_young(struct mm_struct *mm, 337 unsigned long address) 338 { 339 return 0; 340 } 341 342 static inline void mmu_notifier_change_pte(struct mm_struct *mm, 343 unsigned long address, pte_t pte) 344 { 345 } 346 347 static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, 348 unsigned long address) 349 { 350 } 351 352 static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, 353 unsigned long start, unsigned long end) 354 { 355 } 356 357 static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, 358 unsigned long start, unsigned long end) 359 { 360 } 361 362 static inline void mmu_notifier_mm_init(struct mm_struct *mm) 363 { 364 } 365 366 static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) 367 { 368 } 369 370 #define ptep_clear_flush_young_notify ptep_clear_flush_young 371 #define pmdp_clear_flush_young_notify pmdp_clear_flush_young 372 #define ptep_clear_flush_notify ptep_clear_flush 373 #define pmdp_clear_flush_notify pmdp_clear_flush 374 #define pmdp_splitting_flush_notify pmdp_splitting_flush 375 #define set_pte_at_notify set_pte_at 376 377 #endif /* CONFIG_MMU_NOTIFIER */ 378 379 #endif /* _LINUX_MMU_NOTIFIER_H */ 380