1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_SWAPOPS_H
3#define _LINUX_SWAPOPS_H
4
5#include <linux/radix-tree.h>
6#include <linux/bug.h>
7#include <linux/mm_types.h>
8
9#ifdef CONFIG_MMU
10
11/*
12 * swapcache pages are stored in the swapper_space radix tree. We want to
13 * get good packing density in that tree, so the index should be dense in
14 * the low-order bits.
15 *
16 * We arrange the `type' and `offset' fields so that `type' is at the six
17 * high-order bits of the swp_entry_t and `offset' is right-aligned in the
18 * remaining bits. Although `type' itself needs only five bits, we allow for
19 * shmem/tmpfs to shift it all up a further one bit: see swp_to_radix_entry().
20 *
21 * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
22 */
23#define SWP_TYPE_SHIFT (BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT)
24#define SWP_OFFSET_MASK ((1UL << SWP_TYPE_SHIFT) - 1)
25
26/* Clear all flags but only keep swp_entry_t related information */
27static inline pte_t pte_swp_clear_flags(pte_t pte)
28{
29 if (pte_swp_exclusive(pte))
30 pte = pte_swp_clear_exclusive(pte);
31 if (pte_swp_soft_dirty(pte))
32 pte = pte_swp_clear_soft_dirty(pte);
33 if (pte_swp_uffd_wp(pte))
34 pte = pte_swp_clear_uffd_wp(pte);
35 return pte;
36}
37
38/*
39 * Store a type+offset into a swp_entry_t in an arch-independent format
40 */
41static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
42{
43 swp_entry_t ret;
44
45 ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);
46 return ret;
47}
48
49/*
50 * Extract the `type' field from a swp_entry_t. The swp_entry_t is in
51 * arch-independent format
52 */
53static inline unsigned swp_type(swp_entry_t entry)
54{
55 return (entry.val >> SWP_TYPE_SHIFT);
56}
57
58/*
59 * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
60 * arch-independent format
61 */
62static inline pgoff_t swp_offset(swp_entry_t entry)
63{
64 return entry.val & SWP_OFFSET_MASK;
65}
66
67/* check whether a pte points to a swap entry */
68static inline int is_swap_pte(pte_t pte)
69{
70 return !pte_none(pte) && !pte_present(pte);
71}
72
73/*
74 * Convert the arch-dependent pte representation of a swp_entry_t into an
75 * arch-independent swp_entry_t.
76 */
77static inline swp_entry_t pte_to_swp_entry(pte_t pte)
78{
79 swp_entry_t arch_entry;
80
81 pte = pte_swp_clear_flags(pte);
82 arch_entry = __pte_to_swp_entry(pte);
83 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
84}
85
86/*
87 * Convert the arch-independent representation of a swp_entry_t into the
88 * arch-dependent pte representation.
89 */
90static inline pte_t swp_entry_to_pte(swp_entry_t entry)
91{
92 swp_entry_t arch_entry;
93
94 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
95 return __swp_entry_to_pte(arch_entry);
96}
97
98static inline swp_entry_t radix_to_swp_entry(void *arg)
99{
100 swp_entry_t entry;
101
102 entry.val = xa_to_value(arg);
103 return entry;
104}
105
106static inline void *swp_to_radix_entry(swp_entry_t entry)
107{
108 return xa_mk_value(entry.val);
109}
110
111static inline swp_entry_t make_swapin_error_entry(struct page *page)
112{
113 return swp_entry(SWP_SWAPIN_ERROR, page_to_pfn(page));
114}
115
116static inline int is_swapin_error_entry(swp_entry_t entry)
117{
118 return swp_type(entry) == SWP_SWAPIN_ERROR;
119}
120
121#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
122static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
123{
124 return swp_entry(SWP_DEVICE_READ, offset);
125}
126
127static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
128{
129 return swp_entry(SWP_DEVICE_WRITE, offset);
130}
131
132static inline bool is_device_private_entry(swp_entry_t entry)
133{
134 int type = swp_type(entry);
135 return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
136}
137
138static inline bool is_writable_device_private_entry(swp_entry_t entry)
139{
140 return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
141}
142
143static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset)
144{
145 return swp_entry(SWP_DEVICE_EXCLUSIVE_READ, offset);
146}
147
148static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset)
149{
150 return swp_entry(SWP_DEVICE_EXCLUSIVE_WRITE, offset);
151}
152
153static inline bool is_device_exclusive_entry(swp_entry_t entry)
154{
155 return swp_type(entry) == SWP_DEVICE_EXCLUSIVE_READ ||
156 swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE;
157}
158
159static inline bool is_writable_device_exclusive_entry(swp_entry_t entry)
160{
161 return unlikely(swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE);
162}
163#else /* CONFIG_DEVICE_PRIVATE */
164static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
165{
166 return swp_entry(0, 0);
167}
168
169static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
170{
171 return swp_entry(0, 0);
172}
173
174static inline bool is_device_private_entry(swp_entry_t entry)
175{
176 return false;
177}
178
179static inline bool is_writable_device_private_entry(swp_entry_t entry)
180{
181 return false;
182}
183
184static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset)
185{
186 return swp_entry(0, 0);
187}
188
189static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset)
190{
191 return swp_entry(0, 0);
192}
193
194static inline bool is_device_exclusive_entry(swp_entry_t entry)
195{
196 return false;
197}
198
199static inline bool is_writable_device_exclusive_entry(swp_entry_t entry)
200{
201 return false;
202}
203#endif /* CONFIG_DEVICE_PRIVATE */
204
205#ifdef CONFIG_MIGRATION
206static inline int is_migration_entry(swp_entry_t entry)
207{
208 return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
209 swp_type(entry) == SWP_MIGRATION_READ_EXCLUSIVE ||
210 swp_type(entry) == SWP_MIGRATION_WRITE);
211}
212
213static inline int is_writable_migration_entry(swp_entry_t entry)
214{
215 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
216}
217
218static inline int is_readable_migration_entry(swp_entry_t entry)
219{
220 return unlikely(swp_type(entry) == SWP_MIGRATION_READ);
221}
222
223static inline int is_readable_exclusive_migration_entry(swp_entry_t entry)
224{
225 return unlikely(swp_type(entry) == SWP_MIGRATION_READ_EXCLUSIVE);
226}
227
228static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
229{
230 return swp_entry(SWP_MIGRATION_READ, offset);
231}
232
233static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset)
234{
235 return swp_entry(SWP_MIGRATION_READ_EXCLUSIVE, offset);
236}
237
238static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
239{
240 return swp_entry(SWP_MIGRATION_WRITE, offset);
241}
242
243extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
244 spinlock_t *ptl);
245extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
246 unsigned long address);
247#ifdef CONFIG_HUGETLB_PAGE
248extern void __migration_entry_wait_huge(pte_t *ptep, spinlock_t *ptl);
249extern void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte);
250#endif
251#else
252static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
253{
254 return swp_entry(0, 0);
255}
256
257static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset)
258{
259 return swp_entry(0, 0);
260}
261
262static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
263{
264 return swp_entry(0, 0);
265}
266
267static inline int is_migration_entry(swp_entry_t swp)
268{
269 return 0;
270}
271
272static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
273 spinlock_t *ptl) { }
274static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
275 unsigned long address) { }
276#ifdef CONFIG_HUGETLB_PAGE
277static inline void __migration_entry_wait_huge(pte_t *ptep, spinlock_t *ptl) { }
278static inline void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte) { }
279#endif
280static inline int is_writable_migration_entry(swp_entry_t entry)
281{
282 return 0;
283}
284static inline int is_readable_migration_entry(swp_entry_t entry)
285{
286 return 0;
287}
288
289#endif
290
291typedef unsigned long pte_marker;
292
293#define PTE_MARKER_UFFD_WP BIT(0)
294#define PTE_MARKER_MASK (PTE_MARKER_UFFD_WP)
295
296#ifdef CONFIG_PTE_MARKER
297
298static inline swp_entry_t make_pte_marker_entry(pte_marker marker)
299{
300 return swp_entry(SWP_PTE_MARKER, marker);
301}
302
303static inline bool is_pte_marker_entry(swp_entry_t entry)
304{
305 return swp_type(entry) == SWP_PTE_MARKER;
306}
307
308static inline pte_marker pte_marker_get(swp_entry_t entry)
309{
310 return swp_offset(entry) & PTE_MARKER_MASK;
311}
312
313static inline bool is_pte_marker(pte_t pte)
314{
315 return is_swap_pte(pte) && is_pte_marker_entry(pte_to_swp_entry(pte));
316}
317
318#else /* CONFIG_PTE_MARKER */
319
320static inline swp_entry_t make_pte_marker_entry(pte_marker marker)
321{
322 /* This should never be called if !CONFIG_PTE_MARKER */
323 WARN_ON_ONCE(1);
324 return swp_entry(0, 0);
325}
326
327static inline bool is_pte_marker_entry(swp_entry_t entry)
328{
329 return false;
330}
331
332static inline pte_marker pte_marker_get(swp_entry_t entry)
333{
334 return 0;
335}
336
337static inline bool is_pte_marker(pte_t pte)
338{
339 return false;
340}
341
342#endif /* CONFIG_PTE_MARKER */
343
344static inline pte_t make_pte_marker(pte_marker marker)
345{
346 return swp_entry_to_pte(make_pte_marker_entry(marker));
347}
348
349/*
350 * This is a special version to check pte_none() just to cover the case when
351 * the pte is a pte marker. It existed because in many cases the pte marker
352 * should be seen as a none pte; it's just that we have stored some information
353 * onto the none pte so it becomes not-none any more.
354 *
355 * It should be used when the pte is file-backed, ram-based and backing
356 * userspace pages, like shmem. It is not needed upon pgtables that do not
357 * support pte markers at all. For example, it's not needed on anonymous
358 * memory, kernel-only memory (including when the system is during-boot),
359 * non-ram based generic file-system. It's fine to be used even there, but the
360 * extra pte marker check will be pure overhead.
361 *
362 * For systems configured with !CONFIG_PTE_MARKER this will be automatically
363 * optimized to pte_none().
364 */
365static inline int pte_none_mostly(pte_t pte)
366{
367 return pte_none(pte) || is_pte_marker(pte);
368}
369
370static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry)
371{
372 struct page *p = pfn_to_page(swp_offset(entry));
373
374 /*
375 * Any use of migration entries may only occur while the
376 * corresponding page is locked
377 */
378 BUG_ON(is_migration_entry(entry) && !PageLocked(p));
379
380 return p;
381}
382
383/*
384 * A pfn swap entry is a special type of swap entry that always has a pfn stored
385 * in the swap offset. They are used to represent unaddressable device memory
386 * and to restrict access to a page undergoing migration.
387 */
388static inline bool is_pfn_swap_entry(swp_entry_t entry)
389{
390 return is_migration_entry(entry) || is_device_private_entry(entry) ||
391 is_device_exclusive_entry(entry);
392}
393
394struct page_vma_mapped_walk;
395
396#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
397extern int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
398 struct page *page);
399
400extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
401 struct page *new);
402
403extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
404
405static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
406{
407 swp_entry_t arch_entry;
408
409 if (pmd_swp_soft_dirty(pmd))
410 pmd = pmd_swp_clear_soft_dirty(pmd);
411 if (pmd_swp_uffd_wp(pmd))
412 pmd = pmd_swp_clear_uffd_wp(pmd);
413 arch_entry = __pmd_to_swp_entry(pmd);
414 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
415}
416
417static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
418{
419 swp_entry_t arch_entry;
420
421 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
422 return __swp_entry_to_pmd(arch_entry);
423}
424
425static inline int is_pmd_migration_entry(pmd_t pmd)
426{
427 return is_swap_pmd(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
428}
429#else
430static inline int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
431 struct page *page)
432{
433 BUILD_BUG();
434}
435
436static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
437 struct page *new)
438{
439 BUILD_BUG();
440}
441
442static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
443
444static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
445{
446 return swp_entry(0, 0);
447}
448
449static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
450{
451 return __pmd(0);
452}
453
454static inline int is_pmd_migration_entry(pmd_t pmd)
455{
456 return 0;
457}
458#endif
459
460#ifdef CONFIG_MEMORY_FAILURE
461
462extern atomic_long_t num_poisoned_pages __read_mostly;
463
464/*
465 * Support for hardware poisoned pages
466 */
467static inline swp_entry_t make_hwpoison_entry(struct page *page)
468{
469 BUG_ON(!PageLocked(page));
470 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
471}
472
473static inline int is_hwpoison_entry(swp_entry_t entry)
474{
475 return swp_type(entry) == SWP_HWPOISON;
476}
477
478static inline unsigned long hwpoison_entry_to_pfn(swp_entry_t entry)
479{
480 return swp_offset(entry);
481}
482
483static inline void num_poisoned_pages_inc(void)
484{
485 atomic_long_inc(&num_poisoned_pages);
486}
487
488static inline void num_poisoned_pages_dec(void)
489{
490 atomic_long_dec(&num_poisoned_pages);
491}
492
493static inline void num_poisoned_pages_sub(long i)
494{
495 atomic_long_sub(i, &num_poisoned_pages);
496}
497
498#else
499
500static inline swp_entry_t make_hwpoison_entry(struct page *page)
501{
502 return swp_entry(0, 0);
503}
504
505static inline int is_hwpoison_entry(swp_entry_t swp)
506{
507 return 0;
508}
509
510static inline void num_poisoned_pages_inc(void)
511{
512}
513
514static inline void num_poisoned_pages_sub(long i)
515{
516}
517#endif
518
519static inline int non_swap_entry(swp_entry_t entry)
520{
521 return swp_type(entry) >= MAX_SWAPFILES;
522}
523
524#endif /* CONFIG_MMU */
525#endif /* _LINUX_SWAPOPS_H */
526

source code of linux/include/linux/swapops.h