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Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001#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
8struct mmu_notifier;
9struct 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 */
19struct 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
26struct 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 /*
Andrea Arcangeli8ee53822011-01-13 15:47:10 -080065 * 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 /*
Izik Eidus828502d2009-09-21 17:01:51 -070075 * 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 /*
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070084 * 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.
Peter Zijlstra2b575eb2011-05-24 17:12:11 -0700153 * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->mutex).
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700154 * 3. No other concurrent thread can access the list (release)
155 */
156struct mmu_notifier {
157 struct hlist_node hlist;
158 const struct mmu_notifier_ops *ops;
159};
160
161static inline int mm_has_notifiers(struct mm_struct *mm)
162{
163 return unlikely(mm->mmu_notifier_mm);
164}
165
166extern int mmu_notifier_register(struct mmu_notifier *mn,
167 struct mm_struct *mm);
168extern int __mmu_notifier_register(struct mmu_notifier *mn,
169 struct mm_struct *mm);
170extern void mmu_notifier_unregister(struct mmu_notifier *mn,
171 struct mm_struct *mm);
172extern void __mmu_notifier_mm_destroy(struct mm_struct *mm);
173extern void __mmu_notifier_release(struct mm_struct *mm);
174extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
175 unsigned long address);
Andrea Arcangeli8ee53822011-01-13 15:47:10 -0800176extern int __mmu_notifier_test_young(struct mm_struct *mm,
177 unsigned long address);
Izik Eidus828502d2009-09-21 17:01:51 -0700178extern void __mmu_notifier_change_pte(struct mm_struct *mm,
179 unsigned long address, pte_t pte);
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700180extern void __mmu_notifier_invalidate_page(struct mm_struct *mm,
181 unsigned long address);
182extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
183 unsigned long start, unsigned long end);
184extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
185 unsigned long start, unsigned long end);
186
187static inline void mmu_notifier_release(struct mm_struct *mm)
188{
189 if (mm_has_notifiers(mm))
190 __mmu_notifier_release(mm);
191}
192
193static 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
Andrea Arcangeli8ee53822011-01-13 15:47:10 -0800201static 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
Izik Eidus828502d2009-09-21 17:01:51 -0700209static 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
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700216static 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
223static 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
230static 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
237static inline void mmu_notifier_mm_init(struct mm_struct *mm)
238{
239 mm->mmu_notifier_mm = NULL;
240}
241
242static 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.
Figo.zhange732ff72010-10-26 21:01:47 +0800250 * ptep_clear_flush is implemented as macro itself, so this also is
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700251 * 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
Andrea Arcangeli91a4ee22011-01-13 15:46:44 -0800266#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
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700292#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
Andrea Arcangeli91a4ee22011-01-13 15:46:44 -0800303#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
Izik Eidus828502d2009-09-21 17:01:51 -0700314#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
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700324#else /* CONFIG_MMU_NOTIFIER */
325
326static inline void mmu_notifier_release(struct mm_struct *mm)
327{
328}
329
330static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm,
331 unsigned long address)
332{
333 return 0;
334}
335
Andrea Arcangeli8ee53822011-01-13 15:47:10 -0800336static inline int mmu_notifier_test_young(struct mm_struct *mm,
337 unsigned long address)
338{
339 return 0;
340}
341
Izik Eidus828502d2009-09-21 17:01:51 -0700342static inline void mmu_notifier_change_pte(struct mm_struct *mm,
343 unsigned long address, pte_t pte)
344{
345}
346
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700347static inline void mmu_notifier_invalidate_page(struct mm_struct *mm,
348 unsigned long address)
349{
350}
351
352static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm,
353 unsigned long start, unsigned long end)
354{
355}
356
357static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm,
358 unsigned long start, unsigned long end)
359{
360}
361
362static inline void mmu_notifier_mm_init(struct mm_struct *mm)
363{
364}
365
366static inline void mmu_notifier_mm_destroy(struct mm_struct *mm)
367{
368}
369
370#define ptep_clear_flush_young_notify ptep_clear_flush_young
Andrea Arcangeli91a4ee22011-01-13 15:46:44 -0800371#define pmdp_clear_flush_young_notify pmdp_clear_flush_young
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700372#define ptep_clear_flush_notify ptep_clear_flush
Andrea Arcangeli91a4ee22011-01-13 15:46:44 -0800373#define pmdp_clear_flush_notify pmdp_clear_flush
374#define pmdp_splitting_flush_notify pmdp_splitting_flush
Izik Eidus828502d2009-09-21 17:01:51 -0700375#define set_pte_at_notify set_pte_at
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700376
377#endif /* CONFIG_MMU_NOTIFIER */
378
379#endif /* _LINUX_MMU_NOTIFIER_H */