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. If the subsystem
102 * can't guarantee that no additional references are taken to
103 * the pages in the range, it has to implement the
104 * invalidate_range() notifier to remove any references taken
105 * after invalidate_range_start().
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);
149 * invalidate_range() is either called between
150 * invalidate_range_start() and invalidate_range_end() when the
151 * VM has to free pages that where unmapped, but before the
152 * pages are actually freed, or outside of _start()/_end() when
153 * a (remote) TLB is necessary.
155 * If invalidate_range() is used to manage a non-CPU TLB with
156 * shared page-tables, it not necessary to implement the
157 * invalidate_range_start()/end() notifiers, as
158 * invalidate_range() alread catches the points in time when an
159 * external TLB range needs to be flushed.
161 * The invalidate_range() function is called under the ptl
162 * spin-lock and not allowed to sleep.
164 * Note that this function might be called with just a sub-range
165 * of what was passed to invalidate_range_start()/end(), if
166 * called between those functions.
168 void (*invalidate_range)(struct mmu_notifier *mn, struct mm_struct *mm,
169 unsigned long start, unsigned long end);
173 * The notifier chains are protected by mmap_sem and/or the reverse map
174 * semaphores. Notifier chains are only changed when all reverse maps and
175 * the mmap_sem locks are taken.
177 * Therefore notifier chains can only be traversed when either
179 * 1. mmap_sem is held.
180 * 2. One of the reverse map locks is held (i_mmap_rwsem or anon_vma->rwsem).
181 * 3. No other concurrent thread can access the list (release)
183 struct mmu_notifier {
184 struct hlist_node hlist;
185 const struct mmu_notifier_ops *ops;
188 static inline int mm_has_notifiers(struct mm_struct *mm)
190 return unlikely(mm->mmu_notifier_mm);
193 extern int mmu_notifier_register(struct mmu_notifier *mn,
194 struct mm_struct *mm);
195 extern int __mmu_notifier_register(struct mmu_notifier *mn,
196 struct mm_struct *mm);
197 extern void mmu_notifier_unregister(struct mmu_notifier *mn,
198 struct mm_struct *mm);
199 extern void mmu_notifier_unregister_no_release(struct mmu_notifier *mn,
200 struct mm_struct *mm);
201 extern void __mmu_notifier_mm_destroy(struct mm_struct *mm);
202 extern void __mmu_notifier_release(struct mm_struct *mm);
203 extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
206 extern int __mmu_notifier_test_young(struct mm_struct *mm,
207 unsigned long address);
208 extern void __mmu_notifier_change_pte(struct mm_struct *mm,
209 unsigned long address, pte_t pte);
210 extern void __mmu_notifier_invalidate_page(struct mm_struct *mm,
211 unsigned long address);
212 extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
213 unsigned long start, unsigned long end);
214 extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
215 unsigned long start, unsigned long end);
216 extern void __mmu_notifier_invalidate_range(struct mm_struct *mm,
217 unsigned long start, unsigned long end);
219 static inline void mmu_notifier_release(struct mm_struct *mm)
221 if (mm_has_notifiers(mm))
222 __mmu_notifier_release(mm);
225 static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm,
229 if (mm_has_notifiers(mm))
230 return __mmu_notifier_clear_flush_young(mm, start, end);
234 static inline int mmu_notifier_test_young(struct mm_struct *mm,
235 unsigned long address)
237 if (mm_has_notifiers(mm))
238 return __mmu_notifier_test_young(mm, address);
242 static inline void mmu_notifier_change_pte(struct mm_struct *mm,
243 unsigned long address, pte_t pte)
245 if (mm_has_notifiers(mm))
246 __mmu_notifier_change_pte(mm, address, pte);
249 static inline void mmu_notifier_invalidate_page(struct mm_struct *mm,
250 unsigned long address)
252 if (mm_has_notifiers(mm))
253 __mmu_notifier_invalidate_page(mm, address);
256 static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm,
257 unsigned long start, unsigned long end)
259 if (mm_has_notifiers(mm))
260 __mmu_notifier_invalidate_range_start(mm, start, end);
263 static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm,
264 unsigned long start, unsigned long end)
266 if (mm_has_notifiers(mm))
267 __mmu_notifier_invalidate_range_end(mm, start, end);
270 static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
271 unsigned long start, unsigned long end)
273 if (mm_has_notifiers(mm))
274 __mmu_notifier_invalidate_range(mm, start, end);
277 static inline void mmu_notifier_mm_init(struct mm_struct *mm)
279 mm->mmu_notifier_mm = NULL;
282 static inline void mmu_notifier_mm_destroy(struct mm_struct *mm)
284 if (mm_has_notifiers(mm))
285 __mmu_notifier_mm_destroy(mm);
288 #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \
291 struct vm_area_struct *___vma = __vma; \
292 unsigned long ___address = __address; \
293 __young = ptep_clear_flush_young(___vma, ___address, __ptep); \
294 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
301 #define pmdp_clear_flush_young_notify(__vma, __address, __pmdp) \
304 struct vm_area_struct *___vma = __vma; \
305 unsigned long ___address = __address; \
306 __young = pmdp_clear_flush_young(___vma, ___address, __pmdp); \
307 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
314 #define ptep_clear_flush_notify(__vma, __address, __ptep) \
316 unsigned long ___addr = __address & PAGE_MASK; \
317 struct mm_struct *___mm = (__vma)->vm_mm; \
320 ___pte = ptep_clear_flush(__vma, __address, __ptep); \
321 mmu_notifier_invalidate_range(___mm, ___addr, \
322 ___addr + PAGE_SIZE); \
327 #define pmdp_clear_flush_notify(__vma, __haddr, __pmd) \
329 unsigned long ___haddr = __haddr & HPAGE_PMD_MASK; \
330 struct mm_struct *___mm = (__vma)->vm_mm; \
333 ___pmd = pmdp_clear_flush(__vma, __haddr, __pmd); \
334 mmu_notifier_invalidate_range(___mm, ___haddr, \
335 ___haddr + HPAGE_PMD_SIZE); \
340 #define pmdp_get_and_clear_notify(__mm, __haddr, __pmd) \
342 unsigned long ___haddr = __haddr & HPAGE_PMD_MASK; \
345 ___pmd = pmdp_get_and_clear(__mm, __haddr, __pmd); \
346 mmu_notifier_invalidate_range(__mm, ___haddr, \
347 ___haddr + HPAGE_PMD_SIZE); \
353 * set_pte_at_notify() sets the pte _after_ running the notifier.
354 * This is safe to start by updating the secondary MMUs, because the primary MMU
355 * pte invalidate must have already happened with a ptep_clear_flush() before
356 * set_pte_at_notify() has been invoked. Updating the secondary MMUs first is
357 * required when we change both the protection of the mapping from read-only to
358 * read-write and the pfn (like during copy on write page faults). Otherwise the
359 * old page would remain mapped readonly in the secondary MMUs after the new
360 * page is already writable by some CPU through the primary MMU.
362 #define set_pte_at_notify(__mm, __address, __ptep, __pte) \
364 struct mm_struct *___mm = __mm; \
365 unsigned long ___address = __address; \
366 pte_t ___pte = __pte; \
368 mmu_notifier_change_pte(___mm, ___address, ___pte); \
369 set_pte_at(___mm, ___address, __ptep, ___pte); \
372 extern void mmu_notifier_call_srcu(struct rcu_head *rcu,
373 void (*func)(struct rcu_head *rcu));
374 extern void mmu_notifier_synchronize(void);
376 #else /* CONFIG_MMU_NOTIFIER */
378 static inline void mmu_notifier_release(struct mm_struct *mm)
382 static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm,
389 static inline int mmu_notifier_test_young(struct mm_struct *mm,
390 unsigned long address)
395 static inline void mmu_notifier_change_pte(struct mm_struct *mm,
396 unsigned long address, pte_t pte)
400 static inline void mmu_notifier_invalidate_page(struct mm_struct *mm,
401 unsigned long address)
405 static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm,
406 unsigned long start, unsigned long end)
410 static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm,
411 unsigned long start, unsigned long end)
415 static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
416 unsigned long start, unsigned long end)
420 static inline void mmu_notifier_mm_init(struct mm_struct *mm)
424 static inline void mmu_notifier_mm_destroy(struct mm_struct *mm)
428 #define ptep_clear_flush_young_notify ptep_clear_flush_young
429 #define pmdp_clear_flush_young_notify pmdp_clear_flush_young
430 #define ptep_clear_flush_notify ptep_clear_flush
431 #define pmdp_clear_flush_notify pmdp_clear_flush
432 #define pmdp_get_and_clear_notify pmdp_get_and_clear
433 #define set_pte_at_notify set_pte_at
435 #endif /* CONFIG_MMU_NOTIFIER */
437 #endif /* _LINUX_MMU_NOTIFIER_H */