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cddb8a5c AA |
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> | |
21a92735 | 7 | #include <linux/srcu.h> |
cddb8a5c AA |
8 | |
9 | struct mmu_notifier; | |
10 | struct mmu_notifier_ops; | |
11 | ||
12 | #ifdef CONFIG_MMU_NOTIFIER | |
13 | ||
14 | /* | |
15 | * The mmu notifier_mm structure is allocated and installed in | |
16 | * mm->mmu_notifier_mm inside the mm_take_all_locks() protected | |
17 | * critical section and it's released only when mm_count reaches zero | |
18 | * in mmdrop(). | |
19 | */ | |
20 | struct mmu_notifier_mm { | |
21 | /* all mmu notifiers registerd in this mm are queued in this list */ | |
22 | struct hlist_head list; | |
23 | /* to serialize the list modifications and hlist_unhashed */ | |
24 | spinlock_t lock; | |
25 | }; | |
26 | ||
27 | struct mmu_notifier_ops { | |
28 | /* | |
29 | * Called either by mmu_notifier_unregister or when the mm is | |
30 | * being destroyed by exit_mmap, always before all pages are | |
31 | * freed. This can run concurrently with other mmu notifier | |
32 | * methods (the ones invoked outside the mm context) and it | |
33 | * should tear down all secondary mmu mappings and freeze the | |
34 | * secondary mmu. If this method isn't implemented you've to | |
35 | * be sure that nothing could possibly write to the pages | |
36 | * through the secondary mmu by the time the last thread with | |
37 | * tsk->mm == mm exits. | |
38 | * | |
39 | * As side note: the pages freed after ->release returns could | |
40 | * be immediately reallocated by the gart at an alias physical | |
41 | * address with a different cache model, so if ->release isn't | |
42 | * implemented because all _software_ driven memory accesses | |
43 | * through the secondary mmu are terminated by the time the | |
44 | * last thread of this mm quits, you've also to be sure that | |
45 | * speculative _hardware_ operations can't allocate dirty | |
46 | * cachelines in the cpu that could not be snooped and made | |
47 | * coherent with the other read and write operations happening | |
48 | * through the gart alias address, so leading to memory | |
49 | * corruption. | |
50 | */ | |
51 | void (*release)(struct mmu_notifier *mn, | |
52 | struct mm_struct *mm); | |
53 | ||
54 | /* | |
55 | * clear_flush_young is called after the VM is | |
56 | * test-and-clearing the young/accessed bitflag in the | |
57 | * pte. This way the VM will provide proper aging to the | |
58 | * accesses to the page through the secondary MMUs and not | |
59 | * only to the ones through the Linux pte. | |
60 | */ | |
61 | int (*clear_flush_young)(struct mmu_notifier *mn, | |
62 | struct mm_struct *mm, | |
63 | unsigned long address); | |
64 | ||
8ee53820 AA |
65 | /* |
66 | * test_young is called to check the young/accessed bitflag in | |
67 | * the secondary pte. This is used to know if the page is | |
68 | * frequently used without actually clearing the flag or tearing | |
69 | * down the secondary mapping on the page. | |
70 | */ | |
71 | int (*test_young)(struct mmu_notifier *mn, | |
72 | struct mm_struct *mm, | |
73 | unsigned long address); | |
74 | ||
828502d3 IE |
75 | /* |
76 | * change_pte is called in cases that pte mapping to page is changed: | |
77 | * for example, when ksm remaps pte to point to a new shared page. | |
78 | */ | |
79 | void (*change_pte)(struct mmu_notifier *mn, | |
80 | struct mm_struct *mm, | |
81 | unsigned long address, | |
82 | pte_t pte); | |
83 | ||
cddb8a5c AA |
84 | /* |
85 | * Before this is invoked any secondary MMU is still ok to | |
86 | * read/write to the page previously pointed to by the Linux | |
87 | * pte because the page hasn't been freed yet and it won't be | |
88 | * freed until this returns. If required set_page_dirty has to | |
89 | * be called internally to this method. | |
90 | */ | |
91 | void (*invalidate_page)(struct mmu_notifier *mn, | |
92 | struct mm_struct *mm, | |
93 | unsigned long address); | |
94 | ||
95 | /* | |
96 | * invalidate_range_start() and invalidate_range_end() must be | |
97 | * paired and are called only when the mmap_sem and/or the | |
98 | * locks protecting the reverse maps are held. The subsystem | |
99 | * must guarantee that no additional references are taken to | |
100 | * the pages in the range established between the call to | |
101 | * invalidate_range_start() and the matching call to | |
102 | * invalidate_range_end(). | |
103 | * | |
104 | * Invalidation of multiple concurrent ranges may be | |
105 | * optionally permitted by the driver. Either way the | |
106 | * establishment of sptes is forbidden in the range passed to | |
107 | * invalidate_range_begin/end for the whole duration of the | |
108 | * invalidate_range_begin/end critical section. | |
109 | * | |
110 | * invalidate_range_start() is called when all pages in the | |
111 | * range are still mapped and have at least a refcount of one. | |
112 | * | |
113 | * invalidate_range_end() is called when all pages in the | |
114 | * range have been unmapped and the pages have been freed by | |
115 | * the VM. | |
116 | * | |
117 | * The VM will remove the page table entries and potentially | |
118 | * the page between invalidate_range_start() and | |
119 | * invalidate_range_end(). If the page must not be freed | |
120 | * because of pending I/O or other circumstances then the | |
121 | * invalidate_range_start() callback (or the initial mapping | |
122 | * by the driver) must make sure that the refcount is kept | |
123 | * elevated. | |
124 | * | |
125 | * If the driver increases the refcount when the pages are | |
126 | * initially mapped into an address space then either | |
127 | * invalidate_range_start() or invalidate_range_end() may | |
128 | * decrease the refcount. If the refcount is decreased on | |
129 | * invalidate_range_start() then the VM can free pages as page | |
130 | * table entries are removed. If the refcount is only | |
131 | * droppped on invalidate_range_end() then the driver itself | |
132 | * will drop the last refcount but it must take care to flush | |
133 | * any secondary tlb before doing the final free on the | |
134 | * page. Pages will no longer be referenced by the linux | |
135 | * address space but may still be referenced by sptes until | |
136 | * the last refcount is dropped. | |
137 | */ | |
138 | void (*invalidate_range_start)(struct mmu_notifier *mn, | |
139 | struct mm_struct *mm, | |
140 | unsigned long start, unsigned long end); | |
141 | void (*invalidate_range_end)(struct mmu_notifier *mn, | |
142 | struct mm_struct *mm, | |
143 | unsigned long start, unsigned long end); | |
144 | }; | |
145 | ||
146 | /* | |
147 | * The notifier chains are protected by mmap_sem and/or the reverse map | |
148 | * semaphores. Notifier chains are only changed when all reverse maps and | |
149 | * the mmap_sem locks are taken. | |
150 | * | |
151 | * Therefore notifier chains can only be traversed when either | |
152 | * | |
153 | * 1. mmap_sem is held. | |
631b0cfd | 154 | * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->rwsem). |
cddb8a5c AA |
155 | * 3. No other concurrent thread can access the list (release) |
156 | */ | |
157 | struct mmu_notifier { | |
158 | struct hlist_node hlist; | |
159 | const struct mmu_notifier_ops *ops; | |
160 | }; | |
161 | ||
162 | static inline int mm_has_notifiers(struct mm_struct *mm) | |
163 | { | |
164 | return unlikely(mm->mmu_notifier_mm); | |
165 | } | |
166 | ||
167 | extern int mmu_notifier_register(struct mmu_notifier *mn, | |
168 | struct mm_struct *mm); | |
169 | extern int __mmu_notifier_register(struct mmu_notifier *mn, | |
170 | struct mm_struct *mm); | |
171 | extern void mmu_notifier_unregister(struct mmu_notifier *mn, | |
172 | struct mm_struct *mm); | |
173 | extern void __mmu_notifier_mm_destroy(struct mm_struct *mm); | |
174 | extern void __mmu_notifier_release(struct mm_struct *mm); | |
175 | extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm, | |
176 | unsigned long address); | |
8ee53820 AA |
177 | extern int __mmu_notifier_test_young(struct mm_struct *mm, |
178 | unsigned long address); | |
828502d3 IE |
179 | extern void __mmu_notifier_change_pte(struct mm_struct *mm, |
180 | unsigned long address, pte_t pte); | |
cddb8a5c AA |
181 | extern void __mmu_notifier_invalidate_page(struct mm_struct *mm, |
182 | unsigned long address); | |
183 | extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm, | |
184 | unsigned long start, unsigned long end); | |
185 | extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm, | |
186 | unsigned long start, unsigned long end); | |
187 | ||
188 | static inline void mmu_notifier_release(struct mm_struct *mm) | |
189 | { | |
190 | if (mm_has_notifiers(mm)) | |
191 | __mmu_notifier_release(mm); | |
192 | } | |
193 | ||
194 | static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, | |
195 | unsigned long address) | |
196 | { | |
197 | if (mm_has_notifiers(mm)) | |
198 | return __mmu_notifier_clear_flush_young(mm, address); | |
199 | return 0; | |
200 | } | |
201 | ||
8ee53820 AA |
202 | static inline int mmu_notifier_test_young(struct mm_struct *mm, |
203 | unsigned long address) | |
204 | { | |
205 | if (mm_has_notifiers(mm)) | |
206 | return __mmu_notifier_test_young(mm, address); | |
207 | return 0; | |
208 | } | |
209 | ||
828502d3 IE |
210 | static inline void mmu_notifier_change_pte(struct mm_struct *mm, |
211 | unsigned long address, pte_t pte) | |
212 | { | |
213 | if (mm_has_notifiers(mm)) | |
214 | __mmu_notifier_change_pte(mm, address, pte); | |
215 | } | |
216 | ||
cddb8a5c AA |
217 | static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, |
218 | unsigned long address) | |
219 | { | |
220 | if (mm_has_notifiers(mm)) | |
221 | __mmu_notifier_invalidate_page(mm, address); | |
222 | } | |
223 | ||
224 | static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, | |
225 | unsigned long start, unsigned long end) | |
226 | { | |
227 | if (mm_has_notifiers(mm)) | |
228 | __mmu_notifier_invalidate_range_start(mm, start, end); | |
229 | } | |
230 | ||
231 | static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, | |
232 | unsigned long start, unsigned long end) | |
233 | { | |
234 | if (mm_has_notifiers(mm)) | |
235 | __mmu_notifier_invalidate_range_end(mm, start, end); | |
236 | } | |
237 | ||
238 | static inline void mmu_notifier_mm_init(struct mm_struct *mm) | |
239 | { | |
240 | mm->mmu_notifier_mm = NULL; | |
241 | } | |
242 | ||
243 | static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) | |
244 | { | |
245 | if (mm_has_notifiers(mm)) | |
246 | __mmu_notifier_mm_destroy(mm); | |
247 | } | |
248 | ||
cddb8a5c AA |
249 | #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \ |
250 | ({ \ | |
251 | int __young; \ | |
252 | struct vm_area_struct *___vma = __vma; \ | |
253 | unsigned long ___address = __address; \ | |
254 | __young = ptep_clear_flush_young(___vma, ___address, __ptep); \ | |
255 | __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \ | |
256 | ___address); \ | |
257 | __young; \ | |
258 | }) | |
259 | ||
91a4ee26 AA |
260 | #define pmdp_clear_flush_young_notify(__vma, __address, __pmdp) \ |
261 | ({ \ | |
262 | int __young; \ | |
263 | struct vm_area_struct *___vma = __vma; \ | |
264 | unsigned long ___address = __address; \ | |
265 | __young = pmdp_clear_flush_young(___vma, ___address, __pmdp); \ | |
266 | __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \ | |
267 | ___address); \ | |
268 | __young; \ | |
269 | }) | |
270 | ||
48af0d7c XG |
271 | /* |
272 | * set_pte_at_notify() sets the pte _after_ running the notifier. | |
273 | * This is safe to start by updating the secondary MMUs, because the primary MMU | |
274 | * pte invalidate must have already happened with a ptep_clear_flush() before | |
275 | * set_pte_at_notify() has been invoked. Updating the secondary MMUs first is | |
276 | * required when we change both the protection of the mapping from read-only to | |
277 | * read-write and the pfn (like during copy on write page faults). Otherwise the | |
278 | * old page would remain mapped readonly in the secondary MMUs after the new | |
279 | * page is already writable by some CPU through the primary MMU. | |
280 | */ | |
828502d3 IE |
281 | #define set_pte_at_notify(__mm, __address, __ptep, __pte) \ |
282 | ({ \ | |
283 | struct mm_struct *___mm = __mm; \ | |
284 | unsigned long ___address = __address; \ | |
285 | pte_t ___pte = __pte; \ | |
286 | \ | |
828502d3 | 287 | mmu_notifier_change_pte(___mm, ___address, ___pte); \ |
48af0d7c | 288 | set_pte_at(___mm, ___address, __ptep, ___pte); \ |
828502d3 IE |
289 | }) |
290 | ||
cddb8a5c AA |
291 | #else /* CONFIG_MMU_NOTIFIER */ |
292 | ||
293 | static inline void mmu_notifier_release(struct mm_struct *mm) | |
294 | { | |
295 | } | |
296 | ||
297 | static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, | |
298 | unsigned long address) | |
8ee53820 AA |
299 | { |
300 | return 0; | |
301 | } | |
302 | ||
303 | static inline int mmu_notifier_test_young(struct mm_struct *mm, | |
304 | unsigned long address) | |
cddb8a5c AA |
305 | { |
306 | return 0; | |
307 | } | |
308 | ||
828502d3 IE |
309 | static inline void mmu_notifier_change_pte(struct mm_struct *mm, |
310 | unsigned long address, pte_t pte) | |
311 | { | |
312 | } | |
313 | ||
cddb8a5c AA |
314 | static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, |
315 | unsigned long address) | |
316 | { | |
317 | } | |
318 | ||
319 | static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, | |
320 | unsigned long start, unsigned long end) | |
321 | { | |
322 | } | |
323 | ||
324 | static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, | |
325 | unsigned long start, unsigned long end) | |
326 | { | |
327 | } | |
328 | ||
329 | static inline void mmu_notifier_mm_init(struct mm_struct *mm) | |
330 | { | |
331 | } | |
332 | ||
333 | static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) | |
334 | { | |
335 | } | |
336 | ||
337 | #define ptep_clear_flush_young_notify ptep_clear_flush_young | |
91a4ee26 | 338 | #define pmdp_clear_flush_young_notify pmdp_clear_flush_young |
828502d3 | 339 | #define set_pte_at_notify set_pte_at |
cddb8a5c AA |
340 | |
341 | #endif /* CONFIG_MMU_NOTIFIER */ | |
342 | ||
343 | #endif /* _LINUX_MMU_NOTIFIER_H */ |