1 #ifndef _LINUX_MMU_NOTIFIER_H
2 #define _LINUX_MMU_NOTIFIER_H
4 #include <linux/list.h>
5 #include <linux/spinlock.h>
6 #include <linux/mm_types.h>
9 struct mmu_notifier_ops
;
11 #ifdef CONFIG_MMU_NOTIFIER
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
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 */
26 struct mmu_notifier_ops
{
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.
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
50 void (*release
)(struct mmu_notifier
*mn
,
51 struct mm_struct
*mm
);
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.
60 int (*clear_flush_young
)(struct mmu_notifier
*mn
,
62 unsigned long address
);
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.
70 int (*test_young
)(struct mmu_notifier
*mn
,
72 unsigned long address
);
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.
78 void (*change_pte
)(struct mmu_notifier
*mn
,
80 unsigned long address
,
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.
90 void (*invalidate_page
)(struct mmu_notifier
*mn
,
92 unsigned long address
);
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().
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.
109 * invalidate_range_start() is called when all pages in the
110 * range are still mapped and have at least a refcount of one.
112 * invalidate_range_end() is called when all pages in the
113 * range have been unmapped and the pages have been freed by
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
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.
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
);
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.
150 * Therefore notifier chains can only be traversed when either
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)
156 struct mmu_notifier
{
157 struct hlist_node hlist
;
158 const struct mmu_notifier_ops
*ops
;
161 static inline int mm_has_notifiers(struct mm_struct
*mm
)
163 return unlikely(mm
->mmu_notifier_mm
);
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
);
187 static inline void mmu_notifier_release(struct mm_struct
*mm
)
189 if (mm_has_notifiers(mm
))
190 __mmu_notifier_release(mm
);
193 static inline int mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
194 unsigned long address
)
196 if (mm_has_notifiers(mm
))
197 return __mmu_notifier_clear_flush_young(mm
, address
);
201 static inline int mmu_notifier_test_young(struct mm_struct
*mm
,
202 unsigned long address
)
204 if (mm_has_notifiers(mm
))
205 return __mmu_notifier_test_young(mm
, address
);
209 static inline void mmu_notifier_change_pte(struct mm_struct
*mm
,
210 unsigned long address
, pte_t pte
)
212 if (mm_has_notifiers(mm
))
213 __mmu_notifier_change_pte(mm
, address
, pte
);
216 static inline void mmu_notifier_invalidate_page(struct mm_struct
*mm
,
217 unsigned long address
)
219 if (mm_has_notifiers(mm
))
220 __mmu_notifier_invalidate_page(mm
, address
);
223 static inline void mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
224 unsigned long start
, unsigned long end
)
226 if (mm_has_notifiers(mm
))
227 __mmu_notifier_invalidate_range_start(mm
, start
, end
);
230 static inline void mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
231 unsigned long start
, unsigned long end
)
233 if (mm_has_notifiers(mm
))
234 __mmu_notifier_invalidate_range_end(mm
, start
, end
);
237 static inline void mmu_notifier_mm_init(struct mm_struct
*mm
)
239 mm
->mmu_notifier_mm
= NULL
;
242 static inline void mmu_notifier_mm_destroy(struct mm_struct
*mm
)
244 if (mm_has_notifiers(mm
))
245 __mmu_notifier_mm_destroy(mm
);
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.
256 #define ptep_clear_flush_notify(__vma, __address, __ptep) \
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); \
266 #define pmdp_clear_flush_notify(__vma, __address, __pmdp) \
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); \
280 #define pmdp_splitting_flush_notify(__vma, __address, __pmdp) \
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); \
292 #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \
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, \
303 #define pmdp_clear_flush_young_notify(__vma, __address, __pmdp) \
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, \
314 #define set_pte_at_notify(__mm, __address, __ptep, __pte) \
316 struct mm_struct *___mm = __mm; \
317 unsigned long ___address = __address; \
318 pte_t ___pte = __pte; \
320 set_pte_at(___mm, ___address, __ptep, ___pte); \
321 mmu_notifier_change_pte(___mm, ___address, ___pte); \
324 #else /* CONFIG_MMU_NOTIFIER */
326 static inline void mmu_notifier_release(struct mm_struct
*mm
)
330 static inline int mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
331 unsigned long address
)
336 static inline int mmu_notifier_test_young(struct mm_struct
*mm
,
337 unsigned long address
)
342 static inline void mmu_notifier_change_pte(struct mm_struct
*mm
,
343 unsigned long address
, pte_t pte
)
347 static inline void mmu_notifier_invalidate_page(struct mm_struct
*mm
,
348 unsigned long address
)
352 static inline void mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
353 unsigned long start
, unsigned long end
)
357 static inline void mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
358 unsigned long start
, unsigned long end
)
362 static inline void mmu_notifier_mm_init(struct mm_struct
*mm
)
366 static inline void mmu_notifier_mm_destroy(struct mm_struct
*mm
)
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
377 #endif /* CONFIG_MMU_NOTIFIER */
379 #endif /* _LINUX_MMU_NOTIFIER_H */
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