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 * change_pte is called in cases that pte mapping to page is changed:
66 * for example, when ksm remaps pte to point to a new shared page.
68 void (*change_pte
)(struct mmu_notifier
*mn
,
70 unsigned long address
,
74 * Before this is invoked any secondary MMU is still ok to
75 * read/write to the page previously pointed to by the Linux
76 * pte because the page hasn't been freed yet and it won't be
77 * freed until this returns. If required set_page_dirty has to
78 * be called internally to this method.
80 void (*invalidate_page
)(struct mmu_notifier
*mn
,
82 unsigned long address
);
85 * invalidate_range_start() and invalidate_range_end() must be
86 * paired and are called only when the mmap_sem and/or the
87 * locks protecting the reverse maps are held. The subsystem
88 * must guarantee that no additional references are taken to
89 * the pages in the range established between the call to
90 * invalidate_range_start() and the matching call to
91 * invalidate_range_end().
93 * Invalidation of multiple concurrent ranges may be
94 * optionally permitted by the driver. Either way the
95 * establishment of sptes is forbidden in the range passed to
96 * invalidate_range_begin/end for the whole duration of the
97 * invalidate_range_begin/end critical section.
99 * invalidate_range_start() is called when all pages in the
100 * range are still mapped and have at least a refcount of one.
102 * invalidate_range_end() is called when all pages in the
103 * range have been unmapped and the pages have been freed by
106 * The VM will remove the page table entries and potentially
107 * the page between invalidate_range_start() and
108 * invalidate_range_end(). If the page must not be freed
109 * because of pending I/O or other circumstances then the
110 * invalidate_range_start() callback (or the initial mapping
111 * by the driver) must make sure that the refcount is kept
114 * If the driver increases the refcount when the pages are
115 * initially mapped into an address space then either
116 * invalidate_range_start() or invalidate_range_end() may
117 * decrease the refcount. If the refcount is decreased on
118 * invalidate_range_start() then the VM can free pages as page
119 * table entries are removed. If the refcount is only
120 * droppped on invalidate_range_end() then the driver itself
121 * will drop the last refcount but it must take care to flush
122 * any secondary tlb before doing the final free on the
123 * page. Pages will no longer be referenced by the linux
124 * address space but may still be referenced by sptes until
125 * the last refcount is dropped.
127 void (*invalidate_range_start
)(struct mmu_notifier
*mn
,
128 struct mm_struct
*mm
,
129 unsigned long start
, unsigned long end
);
130 void (*invalidate_range_end
)(struct mmu_notifier
*mn
,
131 struct mm_struct
*mm
,
132 unsigned long start
, unsigned long end
);
136 * The notifier chains are protected by mmap_sem and/or the reverse map
137 * semaphores. Notifier chains are only changed when all reverse maps and
138 * the mmap_sem locks are taken.
140 * Therefore notifier chains can only be traversed when either
142 * 1. mmap_sem is held.
143 * 2. One of the reverse map locks is held (i_mmap_lock or anon_vma->lock).
144 * 3. No other concurrent thread can access the list (release)
146 struct mmu_notifier
{
147 struct hlist_node hlist
;
148 const struct mmu_notifier_ops
*ops
;
151 static inline int mm_has_notifiers(struct mm_struct
*mm
)
153 return unlikely(mm
->mmu_notifier_mm
);
156 extern int mmu_notifier_register(struct mmu_notifier
*mn
,
157 struct mm_struct
*mm
);
158 extern int __mmu_notifier_register(struct mmu_notifier
*mn
,
159 struct mm_struct
*mm
);
160 extern void mmu_notifier_unregister(struct mmu_notifier
*mn
,
161 struct mm_struct
*mm
);
162 extern void __mmu_notifier_mm_destroy(struct mm_struct
*mm
);
163 extern void __mmu_notifier_release(struct mm_struct
*mm
);
164 extern int __mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
165 unsigned long address
);
166 extern void __mmu_notifier_change_pte(struct mm_struct
*mm
,
167 unsigned long address
, pte_t pte
);
168 extern void __mmu_notifier_invalidate_page(struct mm_struct
*mm
,
169 unsigned long address
);
170 extern void __mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
171 unsigned long start
, unsigned long end
);
172 extern void __mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
173 unsigned long start
, unsigned long end
);
175 static inline void mmu_notifier_release(struct mm_struct
*mm
)
177 if (mm_has_notifiers(mm
))
178 __mmu_notifier_release(mm
);
181 static inline int mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
182 unsigned long address
)
184 if (mm_has_notifiers(mm
))
185 return __mmu_notifier_clear_flush_young(mm
, address
);
189 static inline void mmu_notifier_change_pte(struct mm_struct
*mm
,
190 unsigned long address
, pte_t pte
)
192 if (mm_has_notifiers(mm
))
193 __mmu_notifier_change_pte(mm
, address
, pte
);
196 static inline void mmu_notifier_invalidate_page(struct mm_struct
*mm
,
197 unsigned long address
)
199 if (mm_has_notifiers(mm
))
200 __mmu_notifier_invalidate_page(mm
, address
);
203 static inline void mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
204 unsigned long start
, unsigned long end
)
206 if (mm_has_notifiers(mm
))
207 __mmu_notifier_invalidate_range_start(mm
, start
, end
);
210 static inline void mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
211 unsigned long start
, unsigned long end
)
213 if (mm_has_notifiers(mm
))
214 __mmu_notifier_invalidate_range_end(mm
, start
, end
);
217 static inline void mmu_notifier_mm_init(struct mm_struct
*mm
)
219 mm
->mmu_notifier_mm
= NULL
;
222 static inline void mmu_notifier_mm_destroy(struct mm_struct
*mm
)
224 if (mm_has_notifiers(mm
))
225 __mmu_notifier_mm_destroy(mm
);
229 * These two macros will sometime replace ptep_clear_flush.
230 * ptep_clear_flush is impleemnted as macro itself, so this also is
231 * implemented as a macro until ptep_clear_flush will converted to an
232 * inline function, to diminish the risk of compilation failure. The
233 * invalidate_page method over time can be moved outside the PT lock
234 * and these two macros can be later removed.
236 #define ptep_clear_flush_notify(__vma, __address, __ptep) \
239 struct vm_area_struct *___vma = __vma; \
240 unsigned long ___address = __address; \
241 __pte = ptep_clear_flush(___vma, ___address, __ptep); \
242 mmu_notifier_invalidate_page(___vma->vm_mm, ___address); \
246 #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \
249 struct vm_area_struct *___vma = __vma; \
250 unsigned long ___address = __address; \
251 __young = ptep_clear_flush_young(___vma, ___address, __ptep); \
252 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
257 #define set_pte_at_notify(__mm, __address, __ptep, __pte) \
259 struct mm_struct *___mm = __mm; \
260 unsigned long ___address = __address; \
261 pte_t ___pte = __pte; \
263 set_pte_at(___mm, ___address, __ptep, ___pte); \
264 mmu_notifier_change_pte(___mm, ___address, ___pte); \
267 #else /* CONFIG_MMU_NOTIFIER */
269 static inline void mmu_notifier_release(struct mm_struct
*mm
)
273 static inline int mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
274 unsigned long address
)
279 static inline void mmu_notifier_change_pte(struct mm_struct
*mm
,
280 unsigned long address
, pte_t pte
)
284 static inline void mmu_notifier_invalidate_page(struct mm_struct
*mm
,
285 unsigned long address
)
289 static inline void mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
290 unsigned long start
, unsigned long end
)
294 static inline void mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
295 unsigned long start
, unsigned long end
)
299 static inline void mmu_notifier_mm_init(struct mm_struct
*mm
)
303 static inline void mmu_notifier_mm_destroy(struct mm_struct
*mm
)
307 #define ptep_clear_flush_young_notify ptep_clear_flush_young
308 #define ptep_clear_flush_notify ptep_clear_flush
309 #define set_pte_at_notify set_pte_at
311 #endif /* CONFIG_MMU_NOTIFIER */
313 #endif /* _LINUX_MMU_NOTIFIER_H */
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