]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - include/linux/mmu_notifier.h
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MMU_NOTIFIER_H
3 #define _LINUX_MMU_NOTIFIER_H
5 #include <linux/list.h>
6 #include <linux/spinlock.h>
7 #include <linux/mm_types.h>
8 #include <linux/srcu.h>
11 struct mmu_notifier_ops
;
13 #ifdef CONFIG_MMU_NOTIFIER
16 * The mmu notifier_mm structure is allocated and installed in
17 * mm->mmu_notifier_mm inside the mm_take_all_locks() protected
18 * critical section and it's released only when mm_count reaches zero
21 struct mmu_notifier_mm
{
22 /* all mmu notifiers registerd in this mm are queued in this list */
23 struct hlist_head list
;
24 /* to serialize the list modifications and hlist_unhashed */
28 struct mmu_notifier_ops
{
30 * Called either by mmu_notifier_unregister or when the mm is
31 * being destroyed by exit_mmap, always before all pages are
32 * freed. This can run concurrently with other mmu notifier
33 * methods (the ones invoked outside the mm context) and it
34 * should tear down all secondary mmu mappings and freeze the
35 * secondary mmu. If this method isn't implemented you've to
36 * be sure that nothing could possibly write to the pages
37 * through the secondary mmu by the time the last thread with
38 * tsk->mm == mm exits.
40 * As side note: the pages freed after ->release returns could
41 * be immediately reallocated by the gart at an alias physical
42 * address with a different cache model, so if ->release isn't
43 * implemented because all _software_ driven memory accesses
44 * through the secondary mmu are terminated by the time the
45 * last thread of this mm quits, you've also to be sure that
46 * speculative _hardware_ operations can't allocate dirty
47 * cachelines in the cpu that could not be snooped and made
48 * coherent with the other read and write operations happening
49 * through the gart alias address, so leading to memory
52 void (*release
)(struct mmu_notifier
*mn
,
53 struct mm_struct
*mm
);
56 * clear_flush_young is called after the VM is
57 * test-and-clearing the young/accessed bitflag in the
58 * pte. This way the VM will provide proper aging to the
59 * accesses to the page through the secondary MMUs and not
60 * only to the ones through the Linux pte.
61 * Start-end is necessary in case the secondary MMU is mapping the page
62 * at a smaller granularity than the primary MMU.
64 int (*clear_flush_young
)(struct mmu_notifier
*mn
,
70 * clear_young is a lightweight version of clear_flush_young. Like the
71 * latter, it is supposed to test-and-clear the young/accessed bitflag
72 * in the secondary pte, but it may omit flushing the secondary tlb.
74 int (*clear_young
)(struct mmu_notifier
*mn
,
80 * test_young is called to check the young/accessed bitflag in
81 * the secondary pte. This is used to know if the page is
82 * frequently used without actually clearing the flag or tearing
83 * down the secondary mapping on the page.
85 int (*test_young
)(struct mmu_notifier
*mn
,
87 unsigned long address
);
90 * change_pte is called in cases that pte mapping to page is changed:
91 * for example, when ksm remaps pte to point to a new shared page.
93 void (*change_pte
)(struct mmu_notifier
*mn
,
95 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_clear_young(struct mm_struct
*mm
,
209 extern int __mmu_notifier_test_young(struct mm_struct
*mm
,
210 unsigned long address
);
211 extern void __mmu_notifier_change_pte(struct mm_struct
*mm
,
212 unsigned long address
, pte_t pte
);
213 extern void __mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
214 unsigned long start
, unsigned long end
);
215 extern void __mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
216 unsigned long start
, unsigned long end
);
217 extern void __mmu_notifier_invalidate_range(struct mm_struct
*mm
,
218 unsigned long start
, unsigned long end
);
220 static inline void mmu_notifier_release(struct mm_struct
*mm
)
222 if (mm_has_notifiers(mm
))
223 __mmu_notifier_release(mm
);
226 static inline int mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
230 if (mm_has_notifiers(mm
))
231 return __mmu_notifier_clear_flush_young(mm
, start
, end
);
235 static inline int mmu_notifier_clear_young(struct mm_struct
*mm
,
239 if (mm_has_notifiers(mm
))
240 return __mmu_notifier_clear_young(mm
, start
, end
);
244 static inline int mmu_notifier_test_young(struct mm_struct
*mm
,
245 unsigned long address
)
247 if (mm_has_notifiers(mm
))
248 return __mmu_notifier_test_young(mm
, address
);
252 static inline void mmu_notifier_change_pte(struct mm_struct
*mm
,
253 unsigned long address
, pte_t pte
)
255 if (mm_has_notifiers(mm
))
256 __mmu_notifier_change_pte(mm
, address
, pte
);
259 static inline void mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
260 unsigned long start
, unsigned long end
)
262 if (mm_has_notifiers(mm
))
263 __mmu_notifier_invalidate_range_start(mm
, start
, end
);
266 static inline void mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
267 unsigned long start
, unsigned long end
)
269 if (mm_has_notifiers(mm
))
270 __mmu_notifier_invalidate_range_end(mm
, start
, end
);
273 static inline void mmu_notifier_invalidate_range(struct mm_struct
*mm
,
274 unsigned long start
, unsigned long end
)
276 if (mm_has_notifiers(mm
))
277 __mmu_notifier_invalidate_range(mm
, start
, end
);
280 static inline void mmu_notifier_mm_init(struct mm_struct
*mm
)
282 mm
->mmu_notifier_mm
= NULL
;
285 static inline void mmu_notifier_mm_destroy(struct mm_struct
*mm
)
287 if (mm_has_notifiers(mm
))
288 __mmu_notifier_mm_destroy(mm
);
291 #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \
294 struct vm_area_struct *___vma = __vma; \
295 unsigned long ___address = __address; \
296 __young = ptep_clear_flush_young(___vma, ___address, __ptep); \
297 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
304 #define pmdp_clear_flush_young_notify(__vma, __address, __pmdp) \
307 struct vm_area_struct *___vma = __vma; \
308 unsigned long ___address = __address; \
309 __young = pmdp_clear_flush_young(___vma, ___address, __pmdp); \
310 __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
317 #define ptep_clear_young_notify(__vma, __address, __ptep) \
320 struct vm_area_struct *___vma = __vma; \
321 unsigned long ___address = __address; \
322 __young = ptep_test_and_clear_young(___vma, ___address, __ptep);\
323 __young |= mmu_notifier_clear_young(___vma->vm_mm, ___address, \
324 ___address + PAGE_SIZE); \
328 #define pmdp_clear_young_notify(__vma, __address, __pmdp) \
331 struct vm_area_struct *___vma = __vma; \
332 unsigned long ___address = __address; \
333 __young = pmdp_test_and_clear_young(___vma, ___address, __pmdp);\
334 __young |= mmu_notifier_clear_young(___vma->vm_mm, ___address, \
335 ___address + PMD_SIZE); \
339 #define ptep_clear_flush_notify(__vma, __address, __ptep) \
341 unsigned long ___addr = __address & PAGE_MASK; \
342 struct mm_struct *___mm = (__vma)->vm_mm; \
345 ___pte = ptep_clear_flush(__vma, __address, __ptep); \
346 mmu_notifier_invalidate_range(___mm, ___addr, \
347 ___addr + PAGE_SIZE); \
352 #define pmdp_huge_clear_flush_notify(__vma, __haddr, __pmd) \
354 unsigned long ___haddr = __haddr & HPAGE_PMD_MASK; \
355 struct mm_struct *___mm = (__vma)->vm_mm; \
358 ___pmd = pmdp_huge_clear_flush(__vma, __haddr, __pmd); \
359 mmu_notifier_invalidate_range(___mm, ___haddr, \
360 ___haddr + HPAGE_PMD_SIZE); \
365 #define pudp_huge_clear_flush_notify(__vma, __haddr, __pud) \
367 unsigned long ___haddr = __haddr & HPAGE_PUD_MASK; \
368 struct mm_struct *___mm = (__vma)->vm_mm; \
371 ___pud = pudp_huge_clear_flush(__vma, __haddr, __pud); \
372 mmu_notifier_invalidate_range(___mm, ___haddr, \
373 ___haddr + HPAGE_PUD_SIZE); \
379 * set_pte_at_notify() sets the pte _after_ running the notifier.
380 * This is safe to start by updating the secondary MMUs, because the primary MMU
381 * pte invalidate must have already happened with a ptep_clear_flush() before
382 * set_pte_at_notify() has been invoked. Updating the secondary MMUs first is
383 * required when we change both the protection of the mapping from read-only to
384 * read-write and the pfn (like during copy on write page faults). Otherwise the
385 * old page would remain mapped readonly in the secondary MMUs after the new
386 * page is already writable by some CPU through the primary MMU.
388 #define set_pte_at_notify(__mm, __address, __ptep, __pte) \
390 struct mm_struct *___mm = __mm; \
391 unsigned long ___address = __address; \
392 pte_t ___pte = __pte; \
394 mmu_notifier_change_pte(___mm, ___address, ___pte); \
395 set_pte_at(___mm, ___address, __ptep, ___pte); \
398 extern void mmu_notifier_call_srcu(struct rcu_head
*rcu
,
399 void (*func
)(struct rcu_head
*rcu
));
400 extern void mmu_notifier_synchronize(void);
402 #else /* CONFIG_MMU_NOTIFIER */
404 static inline int mm_has_notifiers(struct mm_struct
*mm
)
409 static inline void mmu_notifier_release(struct mm_struct
*mm
)
413 static inline int mmu_notifier_clear_flush_young(struct mm_struct
*mm
,
420 static inline int mmu_notifier_test_young(struct mm_struct
*mm
,
421 unsigned long address
)
426 static inline void mmu_notifier_change_pte(struct mm_struct
*mm
,
427 unsigned long address
, pte_t pte
)
431 static inline void mmu_notifier_invalidate_range_start(struct mm_struct
*mm
,
432 unsigned long start
, unsigned long end
)
436 static inline void mmu_notifier_invalidate_range_end(struct mm_struct
*mm
,
437 unsigned long start
, unsigned long end
)
441 static inline void mmu_notifier_invalidate_range(struct mm_struct
*mm
,
442 unsigned long start
, unsigned long end
)
446 static inline void mmu_notifier_mm_init(struct mm_struct
*mm
)
450 static inline void mmu_notifier_mm_destroy(struct mm_struct
*mm
)
454 #define ptep_clear_flush_young_notify ptep_clear_flush_young
455 #define pmdp_clear_flush_young_notify pmdp_clear_flush_young
456 #define ptep_clear_young_notify ptep_test_and_clear_young
457 #define pmdp_clear_young_notify pmdp_test_and_clear_young
458 #define ptep_clear_flush_notify ptep_clear_flush
459 #define pmdp_huge_clear_flush_notify pmdp_huge_clear_flush
460 #define pudp_huge_clear_flush_notify pudp_huge_clear_flush
461 #define set_pte_at_notify set_pte_at
463 #endif /* CONFIG_MMU_NOTIFIER */
465 #endif /* _LINUX_MMU_NOTIFIER_H */