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>
7 #include <linux/srcu.h>
10 struct mmu_notifier_ops
;
12 #ifdef CONFIG_MMU_NOTIFIER
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
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 */
27 struct mmu_notifier_ops
{
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.
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
51 void (*release
)(struct mmu_notifier
*mn
,
52 struct mm_struct
*mm
);
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 * Start-end is necessary in case the secondary MMU is mapping the page
61 * at a smaller granularity than the primary MMU.
63 int (*clear_flush_young
)(struct mmu_notifier
*mn
,
69 * test_young is called to check the young/accessed bitflag in
70 * the secondary pte. This is used to know if the page is
71 * frequently used without actually clearing the flag or tearing
72 * down the secondary mapping on the page.
74 int (*test_young
)(struct mmu_notifier
*mn
,
76 unsigned long address
);
79 * change_pte is called in cases that pte mapping to page is changed:
80 * for example, when ksm remaps pte to point to a new shared page.
82 void (*change_pte
)(struct mmu_notifier
*mn
,
84 unsigned long address
,
88 * Before this is invoked any secondary MMU is still ok to
89 * read/write to the page previously pointed to by the Linux
90 * pte because the page hasn't been freed yet and it won't be
91 * freed until this returns. If required set_page_dirty has to
92 * be called internally to this method.
94 void (*invalidate_page
)(struct mmu_notifier
*mn
,
96 unsigned long address
);
99 * invalidate_range_start() and invalidate_range_end() must be
100 * paired and are called only when the mmap_sem and/or the
101 * locks protecting the reverse maps are held. The subsystem
102 * must guarantee that no additional references are taken to
103 * the pages in the range established between the call to
104 * invalidate_range_start() and the matching call to
105 * invalidate_range_end().
107 * Invalidation of multiple concurrent ranges may be
108 * optionally permitted by the driver. Either way the
109 * establishment of sptes is forbidden in the range passed to
110 * invalidate_range_begin/end for the whole duration of the
111 * invalidate_range_begin/end critical section.
113 * invalidate_range_start() is called when all pages in the
114 * range are still mapped and have at least a refcount of one.
116 * invalidate_range_end() is called when all pages in the
117 * range have been unmapped and the pages have been freed by
120 * The VM will remove the page table entries and potentially
121 * the page between invalidate_range_start() and
122 * invalidate_range_end(). If the page must not be freed
123 * because of pending I/O or other circumstances then the
124 * invalidate_range_start() callback (or the initial mapping
125 * by the driver) must make sure that the refcount is kept
128 * If the driver increases the refcount when the pages are
129 * initially mapped into an address space then either
130 * invalidate_range_start() or invalidate_range_end() may
131 * decrease the refcount. If the refcount is decreased on
132 * invalidate_range_start() then the VM can free pages as page
133 * table entries are removed. If the refcount is only
134 * droppped on invalidate_range_end() then the driver itself
135 * will drop the last refcount but it must take care to flush
136 * any secondary tlb before doing the final free on the
137 * page. Pages will no longer be referenced by the linux
138 * address space but may still be referenced by sptes until
139 * the last refcount is dropped.
141 void (*invalidate_range_start
)(struct mmu_notifier
*mn
,
142 struct mm_struct
*mm
,
143 unsigned long start
, unsigned long end
);
144 void (*invalidate_range_end
)(struct mmu_notifier
*mn
,
145 struct mm_struct
*mm
,
146 unsigned long start
, unsigned long end
);
150 * The notifier chains are protected by mmap_sem and/or the reverse map
151 * semaphores. Notifier chains are only changed when all reverse maps and
152 * the mmap_sem locks are taken.
154 * Therefore notifier chains can only be traversed when either
156 * 1. mmap_sem is held.
157 * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->rwsem).
158 * 3. No other concurrent thread can access the list (release)
160 struct mmu_notifier
{
161 struct hlist_node hlist
;
162 const struct mmu_notifier_ops
*ops
;
165 static inline int mm_has_notifiers(struct mm_struct
*mm
)
167 return unlikely(mm
->mmu_notifier_mm
);
170 extern int mmu_notifier_register(struct mmu_notifier
*mn
,
171 struct mm_struct
*mm
);
172 extern int __mmu_notifier_register(struct mmu_notifier
*mn
,
173 struct mm_struct
*mm
);
174 extern void mmu_notifier_unregister(struct mmu_notifier
*mn
,
175 struct mm_struct
*mm
);
176 extern void mmu_notifier_unregister_no_release(struct mmu_notifier
*mn
,
177 struct mm_struct
*mm
);
178 extern void __mmu_notifier_mm_destroy(struct mm_struct
*mm
);
179 extern void __mmu_notifier_release(struct mm_struct
*mm
);
180 extern int __mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
183 extern int __mmu_notifier_test_young(struct mm_struct
*mm
,
184 unsigned long address
);
185 extern void __mmu_notifier_change_pte(struct mm_struct
*mm
,
186 unsigned long address
, pte_t pte
);
187 extern void __mmu_notifier_invalidate_page(struct mm_struct
*mm
,
188 unsigned long address
);
189 extern void __mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
190 unsigned long start
, unsigned long end
);
191 extern void __mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
192 unsigned long start
, unsigned long end
);
194 static inline void mmu_notifier_release(struct mm_struct
*mm
)
196 if (mm_has_notifiers(mm
))
197 __mmu_notifier_release(mm
);
200 static inline int mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
204 if (mm_has_notifiers(mm
))
205 return __mmu_notifier_clear_flush_young(mm
, start
, end
);
209 static inline int mmu_notifier_test_young(struct mm_struct
*mm
,
210 unsigned long address
)
212 if (mm_has_notifiers(mm
))
213 return __mmu_notifier_test_young(mm
, address
);
217 static inline void mmu_notifier_change_pte(struct mm_struct
*mm
,
218 unsigned long address
, pte_t pte
)
220 if (mm_has_notifiers(mm
))
221 __mmu_notifier_change_pte(mm
, address
, pte
);
224 static inline void mmu_notifier_invalidate_page(struct mm_struct
*mm
,
225 unsigned long address
)
227 if (mm_has_notifiers(mm
))
228 __mmu_notifier_invalidate_page(mm
, address
);
231 static inline void mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
232 unsigned long start
, unsigned long end
)
234 if (mm_has_notifiers(mm
))
235 __mmu_notifier_invalidate_range_start(mm
, start
, end
);
238 static inline void mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
239 unsigned long start
, unsigned long end
)
241 if (mm_has_notifiers(mm
))
242 __mmu_notifier_invalidate_range_end(mm
, start
, end
);
245 static inline void mmu_notifier_mm_init(struct mm_struct
*mm
)
247 mm
->mmu_notifier_mm
= NULL
;
250 static inline void mmu_notifier_mm_destroy(struct mm_struct
*mm
)
252 if (mm_has_notifiers(mm
))
253 __mmu_notifier_mm_destroy(mm
);
256 #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \
259 struct vm_area_struct *___vma = __vma; \
260 unsigned long ___address = __address; \
261 __young = ptep_clear_flush_young(___vma, ___address, __ptep); \
262 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
269 #define pmdp_clear_flush_young_notify(__vma, __address, __pmdp) \
272 struct vm_area_struct *___vma = __vma; \
273 unsigned long ___address = __address; \
274 __young = pmdp_clear_flush_young(___vma, ___address, __pmdp); \
275 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
283 * set_pte_at_notify() sets the pte _after_ running the notifier.
284 * This is safe to start by updating the secondary MMUs, because the primary MMU
285 * pte invalidate must have already happened with a ptep_clear_flush() before
286 * set_pte_at_notify() has been invoked. Updating the secondary MMUs first is
287 * required when we change both the protection of the mapping from read-only to
288 * read-write and the pfn (like during copy on write page faults). Otherwise the
289 * old page would remain mapped readonly in the secondary MMUs after the new
290 * page is already writable by some CPU through the primary MMU.
292 #define set_pte_at_notify(__mm, __address, __ptep, __pte) \
294 struct mm_struct *___mm = __mm; \
295 unsigned long ___address = __address; \
296 pte_t ___pte = __pte; \
298 mmu_notifier_change_pte(___mm, ___address, ___pte); \
299 set_pte_at(___mm, ___address, __ptep, ___pte); \
302 extern void mmu_notifier_call_srcu(struct rcu_head
*rcu
,
303 void (*func
)(struct rcu_head
*rcu
));
304 extern void mmu_notifier_synchronize(void);
306 #else /* CONFIG_MMU_NOTIFIER */
308 static inline void mmu_notifier_release(struct mm_struct
*mm
)
312 static inline int mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
319 static inline int mmu_notifier_test_young(struct mm_struct
*mm
,
320 unsigned long address
)
325 static inline void mmu_notifier_change_pte(struct mm_struct
*mm
,
326 unsigned long address
, pte_t pte
)
330 static inline void mmu_notifier_invalidate_page(struct mm_struct
*mm
,
331 unsigned long address
)
335 static inline void mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
336 unsigned long start
, unsigned long end
)
340 static inline void mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
341 unsigned long start
, unsigned long end
)
345 static inline void mmu_notifier_mm_init(struct mm_struct
*mm
)
349 static inline void mmu_notifier_mm_destroy(struct mm_struct
*mm
)
353 #define ptep_clear_flush_young_notify ptep_clear_flush_young
354 #define pmdp_clear_flush_young_notify pmdp_clear_flush_young
355 #define set_pte_at_notify set_pte_at
357 #endif /* CONFIG_MMU_NOTIFIER */
359 #endif /* _LINUX_MMU_NOTIFIER_H */
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