summaryrefslogtreecommitdiff
path: root/include/linux/swapops.h
blob: cb468e418ea11444ad0fe4be3b551787ba26947f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_SWAPOPS_H
#define _LINUX_SWAPOPS_H

#include <linux/radix-tree.h>
#include <linux/bug.h>
#include <linux/mm_types.h>

#ifdef CONFIG_MMU

#ifdef CONFIG_SWAP
#include <linux/swapfile.h>
#endif	/* CONFIG_SWAP */

/*
 * swapcache pages are stored in the swapper_space radix tree.  We want to
 * get good packing density in that tree, so the index should be dense in
 * the low-order bits.
 *
 * We arrange the `type' and `offset' fields so that `type' is at the six
 * high-order bits of the swp_entry_t and `offset' is right-aligned in the
 * remaining bits.  Although `type' itself needs only five bits, we allow for
 * shmem/tmpfs to shift it all up a further one bit: see swp_to_radix_entry().
 *
 * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
 */
#define SWP_TYPE_SHIFT	(BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT)
#define SWP_OFFSET_MASK	((1UL << SWP_TYPE_SHIFT) - 1)

/*
 * Definitions only for PFN swap entries (see is_pfn_swap_entry()).  To
 * store PFN, we only need SWP_PFN_BITS bits.  Each of the pfn swap entries
 * can use the extra bits to store other information besides PFN.
 */
#ifdef MAX_PHYSMEM_BITS
#define SWP_PFN_BITS		(MAX_PHYSMEM_BITS - PAGE_SHIFT)
#else  /* MAX_PHYSMEM_BITS */
#define SWP_PFN_BITS		min_t(int, \
				      sizeof(phys_addr_t) * 8 - PAGE_SHIFT, \
				      SWP_TYPE_SHIFT)
#endif	/* MAX_PHYSMEM_BITS */
#define SWP_PFN_MASK		(BIT(SWP_PFN_BITS) - 1)

/**
 * Migration swap entry specific bitfield definitions.  Layout:
 *
 *   |----------+--------------------|
 *   | swp_type | swp_offset         |
 *   |----------+--------+-+-+-------|
 *   |          | resv   |D|A|  PFN  |
 *   |----------+--------+-+-+-------|
 *
 * @SWP_MIG_YOUNG_BIT: Whether the page used to have young bit set (bit A)
 * @SWP_MIG_DIRTY_BIT: Whether the page used to have dirty bit set (bit D)
 *
 * Note: A/D bits will be stored in migration entries iff there're enough
 * free bits in arch specific swp offset.  By default we'll ignore A/D bits
 * when migrating a page.  Please refer to migration_entry_supports_ad()
 * for more information.  If there're more bits besides PFN and A/D bits,
 * they should be reserved and always be zeros.
 */
#define SWP_MIG_YOUNG_BIT		(SWP_PFN_BITS)
#define SWP_MIG_DIRTY_BIT		(SWP_PFN_BITS + 1)
#define SWP_MIG_TOTAL_BITS		(SWP_PFN_BITS + 2)

#define SWP_MIG_YOUNG			BIT(SWP_MIG_YOUNG_BIT)
#define SWP_MIG_DIRTY			BIT(SWP_MIG_DIRTY_BIT)

static inline bool is_pfn_swap_entry(swp_entry_t entry);

/* Clear all flags but only keep swp_entry_t related information */
static inline pte_t pte_swp_clear_flags(pte_t pte)
{
	if (pte_swp_exclusive(pte))
		pte = pte_swp_clear_exclusive(pte);
	if (pte_swp_soft_dirty(pte))
		pte = pte_swp_clear_soft_dirty(pte);
	if (pte_swp_uffd_wp(pte))
		pte = pte_swp_clear_uffd_wp(pte);
	return pte;
}

/*
 * Store a type+offset into a swp_entry_t in an arch-independent format
 */
static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
{
	swp_entry_t ret;

	ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);
	return ret;
}

/*
 * Extract the `type' field from a swp_entry_t.  The swp_entry_t is in
 * arch-independent format
 */
static inline unsigned swp_type(swp_entry_t entry)
{
	return (entry.val >> SWP_TYPE_SHIFT);
}

/*
 * Extract the `offset' field from a swp_entry_t.  The swp_entry_t is in
 * arch-independent format
 */
static inline pgoff_t swp_offset(swp_entry_t entry)
{
	return entry.val & SWP_OFFSET_MASK;
}

/*
 * This should only be called upon a pfn swap entry to get the PFN stored
 * in the swap entry.  Please refers to is_pfn_swap_entry() for definition
 * of pfn swap entry.
 */
static inline unsigned long swp_offset_pfn(swp_entry_t entry)
{
	VM_BUG_ON(!is_pfn_swap_entry(entry));
	return swp_offset(entry) & SWP_PFN_MASK;
}

/* check whether a pte points to a swap entry */
static inline int is_swap_pte(pte_t pte)
{
	return !pte_none(pte) && !pte_present(pte);
}

/*
 * Convert the arch-dependent pte representation of a swp_entry_t into an
 * arch-independent swp_entry_t.
 */
static inline swp_entry_t pte_to_swp_entry(pte_t pte)
{
	swp_entry_t arch_entry;

	pte = pte_swp_clear_flags(pte);
	arch_entry = __pte_to_swp_entry(pte);
	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
}

/*
 * Convert the arch-independent representation of a swp_entry_t into the
 * arch-dependent pte representation.
 */
static inline pte_t swp_entry_to_pte(swp_entry_t entry)
{
	swp_entry_t arch_entry;

	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
	return __swp_entry_to_pte(arch_entry);
}

static inline swp_entry_t radix_to_swp_entry(void *arg)
{
	swp_entry_t entry;

	entry.val = xa_to_value(arg);
	return entry;
}

static inline void *swp_to_radix_entry(swp_entry_t entry)
{
	return xa_mk_value(entry.val);
}

#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
{
	return swp_entry(SWP_DEVICE_READ, offset);
}

static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
{
	return swp_entry(SWP_DEVICE_WRITE, offset);
}

static inline bool is_device_private_entry(swp_entry_t entry)
{
	int type = swp_type(entry);
	return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
}

static inline bool is_writable_device_private_entry(swp_entry_t entry)
{
	return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
}

static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset)
{
	return swp_entry(SWP_DEVICE_EXCLUSIVE_READ, offset);
}

static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset)
{
	return swp_entry(SWP_DEVICE_EXCLUSIVE_WRITE, offset);
}

static inline bool is_device_exclusive_entry(swp_entry_t entry)
{
	return swp_type(entry) == SWP_DEVICE_EXCLUSIVE_READ ||
		swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE;
}

static inline bool is_writable_device_exclusive_entry(swp_entry_t entry)
{
	return unlikely(swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE);
}
#else /* CONFIG_DEVICE_PRIVATE */
static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
{
	return swp_entry(0, 0);
}

static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
{
	return swp_entry(0, 0);
}

static inline bool is_device_private_entry(swp_entry_t entry)
{
	return false;
}

static inline bool is_writable_device_private_entry(swp_entry_t entry)
{
	return false;
}

static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset)
{
	return swp_entry(0, 0);
}

static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset)
{
	return swp_entry(0, 0);
}

static inline bool is_device_exclusive_entry(swp_entry_t entry)
{
	return false;
}

static inline bool is_writable_device_exclusive_entry(swp_entry_t entry)
{
	return false;
}
#endif /* CONFIG_DEVICE_PRIVATE */

#ifdef CONFIG_MIGRATION
static inline int is_migration_entry(swp_entry_t entry)
{
	return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
			swp_type(entry) == SWP_MIGRATION_READ_EXCLUSIVE ||
			swp_type(entry) == SWP_MIGRATION_WRITE);
}

static inline int is_writable_migration_entry(swp_entry_t entry)
{
	return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
}

static inline int is_readable_migration_entry(swp_entry_t entry)
{
	return unlikely(swp_type(entry) == SWP_MIGRATION_READ);
}

static inline int is_readable_exclusive_migration_entry(swp_entry_t entry)
{
	return unlikely(swp_type(entry) == SWP_MIGRATION_READ_EXCLUSIVE);
}

static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
{
	return swp_entry(SWP_MIGRATION_READ, offset);
}

static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset)
{
	return swp_entry(SWP_MIGRATION_READ_EXCLUSIVE, offset);
}

static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
{
	return swp_entry(SWP_MIGRATION_WRITE, offset);
}

/*
 * Returns whether the host has large enough swap offset field to support
 * carrying over pgtable A/D bits for page migrations.  The result is
 * pretty much arch specific.
 */
static inline bool migration_entry_supports_ad(void)
{
#ifdef CONFIG_SWAP
	return swap_migration_ad_supported;
#else  /* CONFIG_SWAP */
	return false;
#endif	/* CONFIG_SWAP */
}

static inline swp_entry_t make_migration_entry_young(swp_entry_t entry)
{
	if (migration_entry_supports_ad())
		return swp_entry(swp_type(entry),
				 swp_offset(entry) | SWP_MIG_YOUNG);
	return entry;
}

static inline bool is_migration_entry_young(swp_entry_t entry)
{
	if (migration_entry_supports_ad())
		return swp_offset(entry) & SWP_MIG_YOUNG;
	/* Keep the old behavior of aging page after migration */
	return false;
}

static inline swp_entry_t make_migration_entry_dirty(swp_entry_t entry)
{
	if (migration_entry_supports_ad())
		return swp_entry(swp_type(entry),
				 swp_offset(entry) | SWP_MIG_DIRTY);
	return entry;
}

static inline bool is_migration_entry_dirty(swp_entry_t entry)
{
	if (migration_entry_supports_ad())
		return swp_offset(entry) & SWP_MIG_DIRTY;
	/* Keep the old behavior of clean page after migration */
	return false;
}

extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
					unsigned long address);
extern void migration_entry_wait_huge(struct vm_area_struct *vma, unsigned long addr, pte_t *pte);
#else  /* CONFIG_MIGRATION */
static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
{
	return swp_entry(0, 0);
}

static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset)
{
	return swp_entry(0, 0);
}

static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
{
	return swp_entry(0, 0);
}

static inline int is_migration_entry(swp_entry_t swp)
{
	return 0;
}

static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
					unsigned long address) { }
static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
					     unsigned long addr, pte_t *pte) { }
static inline int is_writable_migration_entry(swp_entry_t entry)
{
	return 0;
}
static inline int is_readable_migration_entry(swp_entry_t entry)
{
	return 0;
}

static inline swp_entry_t make_migration_entry_young(swp_entry_t entry)
{
	return entry;
}

static inline bool is_migration_entry_young(swp_entry_t entry)
{
	return false;
}

static inline swp_entry_t make_migration_entry_dirty(swp_entry_t entry)
{
	return entry;
}

static inline bool is_migration_entry_dirty(swp_entry_t entry)
{
	return false;
}
#endif	/* CONFIG_MIGRATION */

#ifdef CONFIG_MEMORY_FAILURE

/*
 * Support for hardware poisoned pages
 */
static inline swp_entry_t make_hwpoison_entry(struct page *page)
{
	BUG_ON(!PageLocked(page));
	return swp_entry(SWP_HWPOISON, page_to_pfn(page));
}

static inline int is_hwpoison_entry(swp_entry_t entry)
{
	return swp_type(entry) == SWP_HWPOISON;
}

#else

static inline swp_entry_t make_hwpoison_entry(struct page *page)
{
	return swp_entry(0, 0);
}

static inline int is_hwpoison_entry(swp_entry_t swp)
{
	return 0;
}
#endif

typedef unsigned long pte_marker;

#define  PTE_MARKER_UFFD_WP			BIT(0)
/*
 * "Poisoned" here is meant in the very general sense of "future accesses are
 * invalid", instead of referring very specifically to hardware memory errors.
 * This marker is meant to represent any of various different causes of this.
 */
#define  PTE_MARKER_POISONED			BIT(1)
#define  PTE_MARKER_MASK			(BIT(2) - 1)

static inline swp_entry_t make_pte_marker_entry(pte_marker marker)
{
	return swp_entry(SWP_PTE_MARKER, marker);
}

static inline bool is_pte_marker_entry(swp_entry_t entry)
{
	return swp_type(entry) == SWP_PTE_MARKER;
}

static inline pte_marker pte_marker_get(swp_entry_t entry)
{
	return swp_offset(entry) & PTE_MARKER_MASK;
}

static inline bool is_pte_marker(pte_t pte)
{
	return is_swap_pte(pte) && is_pte_marker_entry(pte_to_swp_entry(pte));
}

static inline pte_t make_pte_marker(pte_marker marker)
{
	return swp_entry_to_pte(make_pte_marker_entry(marker));
}

static inline swp_entry_t make_poisoned_swp_entry(void)
{
	return make_pte_marker_entry(PTE_MARKER_POISONED);
}

static inline int is_poisoned_swp_entry(swp_entry_t entry)
{
	return is_pte_marker_entry(entry) &&
	    (pte_marker_get(entry) & PTE_MARKER_POISONED);
}

/*
 * This is a special version to check pte_none() just to cover the case when
 * the pte is a pte marker.  It existed because in many cases the pte marker
 * should be seen as a none pte; it's just that we have stored some information
 * onto the none pte so it becomes not-none any more.
 *
 * It should be used when the pte is file-backed, ram-based and backing
 * userspace pages, like shmem.  It is not needed upon pgtables that do not
 * support pte markers at all.  For example, it's not needed on anonymous
 * memory, kernel-only memory (including when the system is during-boot),
 * non-ram based generic file-system.  It's fine to be used even there, but the
 * extra pte marker check will be pure overhead.
 */
static inline int pte_none_mostly(pte_t pte)
{
	return pte_none(pte) || is_pte_marker(pte);
}

static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry)
{
	struct page *p = pfn_to_page(swp_offset_pfn(entry));

	/*
	 * Any use of migration entries may only occur while the
	 * corresponding page is locked
	 */
	BUG_ON(is_migration_entry(entry) && !PageLocked(p));

	return p;
}

static inline struct folio *pfn_swap_entry_folio(swp_entry_t entry)
{
	struct folio *folio = pfn_folio(swp_offset_pfn(entry));

	/*
	 * Any use of migration entries may only occur while the
	 * corresponding folio is locked
	 */
	BUG_ON(is_migration_entry(entry) && !folio_test_locked(folio));

	return folio;
}

/*
 * A pfn swap entry is a special type of swap entry that always has a pfn stored
 * in the swap offset. They can either be used to represent unaddressable device
 * memory, to restrict access to a page undergoing migration or to represent a
 * pfn which has been hwpoisoned and unmapped.
 */
static inline bool is_pfn_swap_entry(swp_entry_t entry)
{
	/* Make sure the swp offset can always store the needed fields */
	BUILD_BUG_ON(SWP_TYPE_SHIFT < SWP_PFN_BITS);

	return is_migration_entry(entry) || is_device_private_entry(entry) ||
	       is_device_exclusive_entry(entry) || is_hwpoison_entry(entry);
}

struct page_vma_mapped_walk;

#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
extern int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
		struct page *page);

extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
		struct page *new);

extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);

static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
{
	swp_entry_t arch_entry;

	if (pmd_swp_soft_dirty(pmd))
		pmd = pmd_swp_clear_soft_dirty(pmd);
	if (pmd_swp_uffd_wp(pmd))
		pmd = pmd_swp_clear_uffd_wp(pmd);
	arch_entry = __pmd_to_swp_entry(pmd);
	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
}

static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
{
	swp_entry_t arch_entry;

	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
	return __swp_entry_to_pmd(arch_entry);
}

static inline int is_pmd_migration_entry(pmd_t pmd)
{
	return is_swap_pmd(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
}
#else  /* CONFIG_ARCH_ENABLE_THP_MIGRATION */
static inline int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
		struct page *page)
{
	BUILD_BUG();
}

static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
		struct page *new)
{
	BUILD_BUG();
}

static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }

static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
{
	return swp_entry(0, 0);
}

static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
{
	return __pmd(0);
}

static inline int is_pmd_migration_entry(pmd_t pmd)
{
	return 0;
}
#endif  /* CONFIG_ARCH_ENABLE_THP_MIGRATION */

static inline int non_swap_entry(swp_entry_t entry)
{
	return swp_type(entry) >= MAX_SWAPFILES;
}

#endif /* CONFIG_MMU */
#endif /* _LINUX_SWAPOPS_H */