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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 | * Before this is invoked any secondary MMU is still ok to | |
66 | * read/write to the page previously pointed to by the Linux | |
67 | * pte because the page hasn't been freed yet and it won't be | |
68 | * freed until this returns. If required set_page_dirty has to | |
69 | * be called internally to this method. | |
70 | */ | |
71 | void (*invalidate_page)(struct mmu_notifier *mn, | |
72 | struct mm_struct *mm, | |
73 | unsigned long address); | |
74 | ||
75 | /* | |
76 | * invalidate_range_start() and invalidate_range_end() must be | |
77 | * paired and are called only when the mmap_sem and/or the | |
78 | * locks protecting the reverse maps are held. The subsystem | |
79 | * must guarantee that no additional references are taken to | |
80 | * the pages in the range established between the call to | |
81 | * invalidate_range_start() and the matching call to | |
82 | * invalidate_range_end(). | |
83 | * | |
84 | * Invalidation of multiple concurrent ranges may be | |
85 | * optionally permitted by the driver. Either way the | |
86 | * establishment of sptes is forbidden in the range passed to | |
87 | * invalidate_range_begin/end for the whole duration of the | |
88 | * invalidate_range_begin/end critical section. | |
89 | * | |
90 | * invalidate_range_start() is called when all pages in the | |
91 | * range are still mapped and have at least a refcount of one. | |
92 | * | |
93 | * invalidate_range_end() is called when all pages in the | |
94 | * range have been unmapped and the pages have been freed by | |
95 | * the VM. | |
96 | * | |
97 | * The VM will remove the page table entries and potentially | |
98 | * the page between invalidate_range_start() and | |
99 | * invalidate_range_end(). If the page must not be freed | |
100 | * because of pending I/O or other circumstances then the | |
101 | * invalidate_range_start() callback (or the initial mapping | |
102 | * by the driver) must make sure that the refcount is kept | |
103 | * elevated. | |
104 | * | |
105 | * If the driver increases the refcount when the pages are | |
106 | * initially mapped into an address space then either | |
107 | * invalidate_range_start() or invalidate_range_end() may | |
108 | * decrease the refcount. If the refcount is decreased on | |
109 | * invalidate_range_start() then the VM can free pages as page | |
110 | * table entries are removed. If the refcount is only | |
111 | * droppped on invalidate_range_end() then the driver itself | |
112 | * will drop the last refcount but it must take care to flush | |
113 | * any secondary tlb before doing the final free on the | |
114 | * page. Pages will no longer be referenced by the linux | |
115 | * address space but may still be referenced by sptes until | |
116 | * the last refcount is dropped. | |
117 | */ | |
118 | void (*invalidate_range_start)(struct mmu_notifier *mn, | |
119 | struct mm_struct *mm, | |
120 | unsigned long start, unsigned long end); | |
121 | void (*invalidate_range_end)(struct mmu_notifier *mn, | |
122 | struct mm_struct *mm, | |
123 | unsigned long start, unsigned long end); | |
124 | }; | |
125 | ||
126 | /* | |
127 | * The notifier chains are protected by mmap_sem and/or the reverse map | |
128 | * semaphores. Notifier chains are only changed when all reverse maps and | |
129 | * the mmap_sem locks are taken. | |
130 | * | |
131 | * Therefore notifier chains can only be traversed when either | |
132 | * | |
133 | * 1. mmap_sem is held. | |
134 | * 2. One of the reverse map locks is held (i_mmap_lock or anon_vma->lock). | |
135 | * 3. No other concurrent thread can access the list (release) | |
136 | */ | |
137 | struct mmu_notifier { | |
138 | struct hlist_node hlist; | |
139 | const struct mmu_notifier_ops *ops; | |
140 | }; | |
141 | ||
142 | static inline int mm_has_notifiers(struct mm_struct *mm) | |
143 | { | |
144 | return unlikely(mm->mmu_notifier_mm); | |
145 | } | |
146 | ||
147 | extern int mmu_notifier_register(struct mmu_notifier *mn, | |
148 | struct mm_struct *mm); | |
149 | extern int __mmu_notifier_register(struct mmu_notifier *mn, | |
150 | struct mm_struct *mm); | |
151 | extern void mmu_notifier_unregister(struct mmu_notifier *mn, | |
152 | struct mm_struct *mm); | |
153 | extern void __mmu_notifier_mm_destroy(struct mm_struct *mm); | |
154 | extern void __mmu_notifier_release(struct mm_struct *mm); | |
155 | extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm, | |
156 | unsigned long address); | |
157 | extern void __mmu_notifier_invalidate_page(struct mm_struct *mm, | |
158 | unsigned long address); | |
159 | extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm, | |
160 | unsigned long start, unsigned long end); | |
161 | extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm, | |
162 | unsigned long start, unsigned long end); | |
163 | ||
164 | static inline void mmu_notifier_release(struct mm_struct *mm) | |
165 | { | |
166 | if (mm_has_notifiers(mm)) | |
167 | __mmu_notifier_release(mm); | |
168 | } | |
169 | ||
170 | static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, | |
171 | unsigned long address) | |
172 | { | |
173 | if (mm_has_notifiers(mm)) | |
174 | return __mmu_notifier_clear_flush_young(mm, address); | |
175 | return 0; | |
176 | } | |
177 | ||
178 | static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, | |
179 | unsigned long address) | |
180 | { | |
181 | if (mm_has_notifiers(mm)) | |
182 | __mmu_notifier_invalidate_page(mm, address); | |
183 | } | |
184 | ||
185 | static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, | |
186 | unsigned long start, unsigned long end) | |
187 | { | |
188 | if (mm_has_notifiers(mm)) | |
189 | __mmu_notifier_invalidate_range_start(mm, start, end); | |
190 | } | |
191 | ||
192 | static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, | |
193 | unsigned long start, unsigned long end) | |
194 | { | |
195 | if (mm_has_notifiers(mm)) | |
196 | __mmu_notifier_invalidate_range_end(mm, start, end); | |
197 | } | |
198 | ||
199 | static inline void mmu_notifier_mm_init(struct mm_struct *mm) | |
200 | { | |
201 | mm->mmu_notifier_mm = NULL; | |
202 | } | |
203 | ||
204 | static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) | |
205 | { | |
206 | if (mm_has_notifiers(mm)) | |
207 | __mmu_notifier_mm_destroy(mm); | |
208 | } | |
209 | ||
210 | /* | |
211 | * These two macros will sometime replace ptep_clear_flush. | |
212 | * ptep_clear_flush is impleemnted as macro itself, so this also is | |
213 | * implemented as a macro until ptep_clear_flush will converted to an | |
214 | * inline function, to diminish the risk of compilation failure. The | |
215 | * invalidate_page method over time can be moved outside the PT lock | |
216 | * and these two macros can be later removed. | |
217 | */ | |
218 | #define ptep_clear_flush_notify(__vma, __address, __ptep) \ | |
219 | ({ \ | |
220 | pte_t __pte; \ | |
221 | struct vm_area_struct *___vma = __vma; \ | |
222 | unsigned long ___address = __address; \ | |
223 | __pte = ptep_clear_flush(___vma, ___address, __ptep); \ | |
224 | mmu_notifier_invalidate_page(___vma->vm_mm, ___address); \ | |
225 | __pte; \ | |
226 | }) | |
227 | ||
228 | #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \ | |
229 | ({ \ | |
230 | int __young; \ | |
231 | struct vm_area_struct *___vma = __vma; \ | |
232 | unsigned long ___address = __address; \ | |
233 | __young = ptep_clear_flush_young(___vma, ___address, __ptep); \ | |
234 | __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \ | |
235 | ___address); \ | |
236 | __young; \ | |
237 | }) | |
238 | ||
239 | #else /* CONFIG_MMU_NOTIFIER */ | |
240 | ||
241 | static inline void mmu_notifier_release(struct mm_struct *mm) | |
242 | { | |
243 | } | |
244 | ||
245 | static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, | |
246 | unsigned long address) | |
247 | { | |
248 | return 0; | |
249 | } | |
250 | ||
251 | static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, | |
252 | unsigned long address) | |
253 | { | |
254 | } | |
255 | ||
256 | static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, | |
257 | unsigned long start, unsigned long end) | |
258 | { | |
259 | } | |
260 | ||
261 | static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, | |
262 | unsigned long start, unsigned long end) | |
263 | { | |
264 | } | |
265 | ||
266 | static inline void mmu_notifier_mm_init(struct mm_struct *mm) | |
267 | { | |
268 | } | |
269 | ||
270 | static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) | |
271 | { | |
272 | } | |
273 | ||
274 | #define ptep_clear_flush_young_notify ptep_clear_flush_young | |
275 | #define ptep_clear_flush_notify ptep_clear_flush | |
276 | ||
277 | #endif /* CONFIG_MMU_NOTIFIER */ | |
278 | ||
279 | #endif /* _LINUX_MMU_NOTIFIER_H */ |