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 #ifdef CONFIG_SWAP
12 #include <linux/swapfile.h>
13 #endif	/* CONFIG_SWAP */
14 
15 /*
16  * swapcache pages are stored in the swapper_space radix tree.  We want to
17  * get good packing density in that tree, so the index should be dense in
18  * the low-order bits.
19  *
20  * We arrange the `type' and `offset' fields so that `type' is at the six
21  * high-order bits of the swp_entry_t and `offset' is right-aligned in the
22  * remaining bits.  Although `type' itself needs only five bits, we allow for
23  * shmem/tmpfs to shift it all up a further one bit: see swp_to_radix_entry().
24  *
25  * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
26  */
27 #define SWP_TYPE_SHIFT	(BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT)
28 #define SWP_OFFSET_MASK	((1UL << SWP_TYPE_SHIFT) - 1)
29 
30 /*
31  * Definitions only for PFN swap entries (see is_pfn_swap_entry()).  To
32  * store PFN, we only need SWP_PFN_BITS bits.  Each of the pfn swap entries
33  * can use the extra bits to store other information besides PFN.
34  */
35 #ifdef MAX_PHYSMEM_BITS
36 #define SWP_PFN_BITS		(MAX_PHYSMEM_BITS - PAGE_SHIFT)
37 #else  /* MAX_PHYSMEM_BITS */
38 #define SWP_PFN_BITS		min_t(int, \
39 				      sizeof(phys_addr_t) * 8 - PAGE_SHIFT, \
40 				      SWP_TYPE_SHIFT)
41 #endif	/* MAX_PHYSMEM_BITS */
42 #define SWP_PFN_MASK		(BIT(SWP_PFN_BITS) - 1)
43 
44 /**
45  * Migration swap entry specific bitfield definitions.  Layout:
46  *
47  *   |----------+--------------------|
48  *   | swp_type | swp_offset         |
49  *   |----------+--------+-+-+-------|
50  *   |          | resv   |D|A|  PFN  |
51  *   |----------+--------+-+-+-------|
52  *
53  * @SWP_MIG_YOUNG_BIT: Whether the page used to have young bit set (bit A)
54  * @SWP_MIG_DIRTY_BIT: Whether the page used to have dirty bit set (bit D)
55  *
56  * Note: A/D bits will be stored in migration entries iff there're enough
57  * free bits in arch specific swp offset.  By default we'll ignore A/D bits
58  * when migrating a page.  Please refer to migration_entry_supports_ad()
59  * for more information.  If there're more bits besides PFN and A/D bits,
60  * they should be reserved and always be zeros.
61  */
62 #define SWP_MIG_YOUNG_BIT		(SWP_PFN_BITS)
63 #define SWP_MIG_DIRTY_BIT		(SWP_PFN_BITS + 1)
64 #define SWP_MIG_TOTAL_BITS		(SWP_PFN_BITS + 2)
65 
66 #define SWP_MIG_YOUNG			BIT(SWP_MIG_YOUNG_BIT)
67 #define SWP_MIG_DIRTY			BIT(SWP_MIG_DIRTY_BIT)
68 
69 static inline bool is_pfn_swap_entry(swp_entry_t entry);
70 
71 /* Clear all flags but only keep swp_entry_t related information */
pte_swp_clear_flags(pte_t pte)72 static inline pte_t pte_swp_clear_flags(pte_t pte)
73 {
74 	if (pte_swp_exclusive(pte))
75 		pte = pte_swp_clear_exclusive(pte);
76 	if (pte_swp_soft_dirty(pte))
77 		pte = pte_swp_clear_soft_dirty(pte);
78 	if (pte_swp_uffd_wp(pte))
79 		pte = pte_swp_clear_uffd_wp(pte);
80 	return pte;
81 }
82 
83 /*
84  * Store a type+offset into a swp_entry_t in an arch-independent format
85  */
swp_entry(unsigned long type,pgoff_t offset)86 static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
87 {
88 	swp_entry_t ret;
89 
90 	ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);
91 	return ret;
92 }
93 
94 /*
95  * Extract the `type' field from a swp_entry_t.  The swp_entry_t is in
96  * arch-independent format
97  */
swp_type(swp_entry_t entry)98 static inline unsigned swp_type(swp_entry_t entry)
99 {
100 	return (entry.val >> SWP_TYPE_SHIFT);
101 }
102 
103 /*
104  * Extract the `offset' field from a swp_entry_t.  The swp_entry_t is in
105  * arch-independent format
106  */
swp_offset(swp_entry_t entry)107 static inline pgoff_t swp_offset(swp_entry_t entry)
108 {
109 	return entry.val & SWP_OFFSET_MASK;
110 }
111 
112 /*
113  * This should only be called upon a pfn swap entry to get the PFN stored
114  * in the swap entry.  Please refers to is_pfn_swap_entry() for definition
115  * of pfn swap entry.
116  */
swp_offset_pfn(swp_entry_t entry)117 static inline unsigned long swp_offset_pfn(swp_entry_t entry)
118 {
119 	VM_BUG_ON(!is_pfn_swap_entry(entry));
120 	return swp_offset(entry) & SWP_PFN_MASK;
121 }
122 
123 /* check whether a pte points to a swap entry */
is_swap_pte(pte_t pte)124 static inline int is_swap_pte(pte_t pte)
125 {
126 	return !pte_none(pte) && !pte_present(pte);
127 }
128 
129 /*
130  * Convert the arch-dependent pte representation of a swp_entry_t into an
131  * arch-independent swp_entry_t.
132  */
pte_to_swp_entry(pte_t pte)133 static inline swp_entry_t pte_to_swp_entry(pte_t pte)
134 {
135 	swp_entry_t arch_entry;
136 
137 	pte = pte_swp_clear_flags(pte);
138 	arch_entry = __pte_to_swp_entry(pte);
139 	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
140 }
141 
142 /*
143  * Convert the arch-independent representation of a swp_entry_t into the
144  * arch-dependent pte representation.
145  */
swp_entry_to_pte(swp_entry_t entry)146 static inline pte_t swp_entry_to_pte(swp_entry_t entry)
147 {
148 	swp_entry_t arch_entry;
149 
150 	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
151 	return __swp_entry_to_pte(arch_entry);
152 }
153 
radix_to_swp_entry(void * arg)154 static inline swp_entry_t radix_to_swp_entry(void *arg)
155 {
156 	swp_entry_t entry;
157 
158 	entry.val = xa_to_value(arg);
159 	return entry;
160 }
161 
swp_to_radix_entry(swp_entry_t entry)162 static inline void *swp_to_radix_entry(swp_entry_t entry)
163 {
164 	return xa_mk_value(entry.val);
165 }
166 
167 #if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
make_readable_device_private_entry(pgoff_t offset)168 static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
169 {
170 	return swp_entry(SWP_DEVICE_READ, offset);
171 }
172 
make_writable_device_private_entry(pgoff_t offset)173 static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
174 {
175 	return swp_entry(SWP_DEVICE_WRITE, offset);
176 }
177 
is_device_private_entry(swp_entry_t entry)178 static inline bool is_device_private_entry(swp_entry_t entry)
179 {
180 	int type = swp_type(entry);
181 	return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
182 }
183 
is_writable_device_private_entry(swp_entry_t entry)184 static inline bool is_writable_device_private_entry(swp_entry_t entry)
185 {
186 	return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
187 }
188 
make_readable_device_exclusive_entry(pgoff_t offset)189 static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset)
190 {
191 	return swp_entry(SWP_DEVICE_EXCLUSIVE_READ, offset);
192 }
193 
make_writable_device_exclusive_entry(pgoff_t offset)194 static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset)
195 {
196 	return swp_entry(SWP_DEVICE_EXCLUSIVE_WRITE, offset);
197 }
198 
is_device_exclusive_entry(swp_entry_t entry)199 static inline bool is_device_exclusive_entry(swp_entry_t entry)
200 {
201 	return swp_type(entry) == SWP_DEVICE_EXCLUSIVE_READ ||
202 		swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE;
203 }
204 
is_writable_device_exclusive_entry(swp_entry_t entry)205 static inline bool is_writable_device_exclusive_entry(swp_entry_t entry)
206 {
207 	return unlikely(swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE);
208 }
209 #else /* CONFIG_DEVICE_PRIVATE */
make_readable_device_private_entry(pgoff_t offset)210 static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
211 {
212 	return swp_entry(0, 0);
213 }
214 
make_writable_device_private_entry(pgoff_t offset)215 static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
216 {
217 	return swp_entry(0, 0);
218 }
219 
is_device_private_entry(swp_entry_t entry)220 static inline bool is_device_private_entry(swp_entry_t entry)
221 {
222 	return false;
223 }
224 
is_writable_device_private_entry(swp_entry_t entry)225 static inline bool is_writable_device_private_entry(swp_entry_t entry)
226 {
227 	return false;
228 }
229 
make_readable_device_exclusive_entry(pgoff_t offset)230 static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset)
231 {
232 	return swp_entry(0, 0);
233 }
234 
make_writable_device_exclusive_entry(pgoff_t offset)235 static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset)
236 {
237 	return swp_entry(0, 0);
238 }
239 
is_device_exclusive_entry(swp_entry_t entry)240 static inline bool is_device_exclusive_entry(swp_entry_t entry)
241 {
242 	return false;
243 }
244 
is_writable_device_exclusive_entry(swp_entry_t entry)245 static inline bool is_writable_device_exclusive_entry(swp_entry_t entry)
246 {
247 	return false;
248 }
249 #endif /* CONFIG_DEVICE_PRIVATE */
250 
251 #ifdef CONFIG_MIGRATION
is_migration_entry(swp_entry_t entry)252 static inline int is_migration_entry(swp_entry_t entry)
253 {
254 	return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
255 			swp_type(entry) == SWP_MIGRATION_READ_EXCLUSIVE ||
256 			swp_type(entry) == SWP_MIGRATION_WRITE);
257 }
258 
is_writable_migration_entry(swp_entry_t entry)259 static inline int is_writable_migration_entry(swp_entry_t entry)
260 {
261 	return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
262 }
263 
is_readable_migration_entry(swp_entry_t entry)264 static inline int is_readable_migration_entry(swp_entry_t entry)
265 {
266 	return unlikely(swp_type(entry) == SWP_MIGRATION_READ);
267 }
268 
is_readable_exclusive_migration_entry(swp_entry_t entry)269 static inline int is_readable_exclusive_migration_entry(swp_entry_t entry)
270 {
271 	return unlikely(swp_type(entry) == SWP_MIGRATION_READ_EXCLUSIVE);
272 }
273 
make_readable_migration_entry(pgoff_t offset)274 static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
275 {
276 	return swp_entry(SWP_MIGRATION_READ, offset);
277 }
278 
make_readable_exclusive_migration_entry(pgoff_t offset)279 static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset)
280 {
281 	return swp_entry(SWP_MIGRATION_READ_EXCLUSIVE, offset);
282 }
283 
make_writable_migration_entry(pgoff_t offset)284 static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
285 {
286 	return swp_entry(SWP_MIGRATION_WRITE, offset);
287 }
288 
289 /*
290  * Returns whether the host has large enough swap offset field to support
291  * carrying over pgtable A/D bits for page migrations.  The result is
292  * pretty much arch specific.
293  */
migration_entry_supports_ad(void)294 static inline bool migration_entry_supports_ad(void)
295 {
296 #ifdef CONFIG_SWAP
297 	return swap_migration_ad_supported;
298 #else  /* CONFIG_SWAP */
299 	return false;
300 #endif	/* CONFIG_SWAP */
301 }
302 
make_migration_entry_young(swp_entry_t entry)303 static inline swp_entry_t make_migration_entry_young(swp_entry_t entry)
304 {
305 	if (migration_entry_supports_ad())
306 		return swp_entry(swp_type(entry),
307 				 swp_offset(entry) | SWP_MIG_YOUNG);
308 	return entry;
309 }
310 
is_migration_entry_young(swp_entry_t entry)311 static inline bool is_migration_entry_young(swp_entry_t entry)
312 {
313 	if (migration_entry_supports_ad())
314 		return swp_offset(entry) & SWP_MIG_YOUNG;
315 	/* Keep the old behavior of aging page after migration */
316 	return false;
317 }
318 
make_migration_entry_dirty(swp_entry_t entry)319 static inline swp_entry_t make_migration_entry_dirty(swp_entry_t entry)
320 {
321 	if (migration_entry_supports_ad())
322 		return swp_entry(swp_type(entry),
323 				 swp_offset(entry) | SWP_MIG_DIRTY);
324 	return entry;
325 }
326 
is_migration_entry_dirty(swp_entry_t entry)327 static inline bool is_migration_entry_dirty(swp_entry_t entry)
328 {
329 	if (migration_entry_supports_ad())
330 		return swp_offset(entry) & SWP_MIG_DIRTY;
331 	/* Keep the old behavior of clean page after migration */
332 	return false;
333 }
334 
335 extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
336 					unsigned long address);
337 extern void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte);
338 #else  /* CONFIG_MIGRATION */
make_readable_migration_entry(pgoff_t offset)339 static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
340 {
341 	return swp_entry(0, 0);
342 }
343 
make_readable_exclusive_migration_entry(pgoff_t offset)344 static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset)
345 {
346 	return swp_entry(0, 0);
347 }
348 
make_writable_migration_entry(pgoff_t offset)349 static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
350 {
351 	return swp_entry(0, 0);
352 }
353 
is_migration_entry(swp_entry_t swp)354 static inline int is_migration_entry(swp_entry_t swp)
355 {
356 	return 0;
357 }
358 
migration_entry_wait(struct mm_struct * mm,pmd_t * pmd,unsigned long address)359 static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
360 					unsigned long address) { }
migration_entry_wait_huge(struct vm_area_struct * vma,pte_t * pte)361 static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
362 					pte_t *pte) { }
is_writable_migration_entry(swp_entry_t entry)363 static inline int is_writable_migration_entry(swp_entry_t entry)
364 {
365 	return 0;
366 }
is_readable_migration_entry(swp_entry_t entry)367 static inline int is_readable_migration_entry(swp_entry_t entry)
368 {
369 	return 0;
370 }
371 
make_migration_entry_young(swp_entry_t entry)372 static inline swp_entry_t make_migration_entry_young(swp_entry_t entry)
373 {
374 	return entry;
375 }
376 
is_migration_entry_young(swp_entry_t entry)377 static inline bool is_migration_entry_young(swp_entry_t entry)
378 {
379 	return false;
380 }
381 
make_migration_entry_dirty(swp_entry_t entry)382 static inline swp_entry_t make_migration_entry_dirty(swp_entry_t entry)
383 {
384 	return entry;
385 }
386 
is_migration_entry_dirty(swp_entry_t entry)387 static inline bool is_migration_entry_dirty(swp_entry_t entry)
388 {
389 	return false;
390 }
391 #endif	/* CONFIG_MIGRATION */
392 
393 typedef unsigned long pte_marker;
394 
395 #define  PTE_MARKER_UFFD_WP			BIT(0)
396 /*
397  * "Poisoned" here is meant in the very general sense of "future accesses are
398  * invalid", instead of referring very specifically to hardware memory errors.
399  * This marker is meant to represent any of various different causes of this.
400  */
401 #define  PTE_MARKER_POISONED			BIT(1)
402 #define  PTE_MARKER_MASK			(BIT(2) - 1)
403 
make_pte_marker_entry(pte_marker marker)404 static inline swp_entry_t make_pte_marker_entry(pte_marker marker)
405 {
406 	return swp_entry(SWP_PTE_MARKER, marker);
407 }
408 
is_pte_marker_entry(swp_entry_t entry)409 static inline bool is_pte_marker_entry(swp_entry_t entry)
410 {
411 	return swp_type(entry) == SWP_PTE_MARKER;
412 }
413 
pte_marker_get(swp_entry_t entry)414 static inline pte_marker pte_marker_get(swp_entry_t entry)
415 {
416 	return swp_offset(entry) & PTE_MARKER_MASK;
417 }
418 
is_pte_marker(pte_t pte)419 static inline bool is_pte_marker(pte_t pte)
420 {
421 	return is_swap_pte(pte) && is_pte_marker_entry(pte_to_swp_entry(pte));
422 }
423 
make_pte_marker(pte_marker marker)424 static inline pte_t make_pte_marker(pte_marker marker)
425 {
426 	return swp_entry_to_pte(make_pte_marker_entry(marker));
427 }
428 
make_poisoned_swp_entry(void)429 static inline swp_entry_t make_poisoned_swp_entry(void)
430 {
431 	return make_pte_marker_entry(PTE_MARKER_POISONED);
432 }
433 
is_poisoned_swp_entry(swp_entry_t entry)434 static inline int is_poisoned_swp_entry(swp_entry_t entry)
435 {
436 	return is_pte_marker_entry(entry) &&
437 	    (pte_marker_get(entry) & PTE_MARKER_POISONED);
438 }
439 
440 /*
441  * This is a special version to check pte_none() just to cover the case when
442  * the pte is a pte marker.  It existed because in many cases the pte marker
443  * should be seen as a none pte; it's just that we have stored some information
444  * onto the none pte so it becomes not-none any more.
445  *
446  * It should be used when the pte is file-backed, ram-based and backing
447  * userspace pages, like shmem.  It is not needed upon pgtables that do not
448  * support pte markers at all.  For example, it's not needed on anonymous
449  * memory, kernel-only memory (including when the system is during-boot),
450  * non-ram based generic file-system.  It's fine to be used even there, but the
451  * extra pte marker check will be pure overhead.
452  */
pte_none_mostly(pte_t pte)453 static inline int pte_none_mostly(pte_t pte)
454 {
455 	return pte_none(pte) || is_pte_marker(pte);
456 }
457 
pfn_swap_entry_to_page(swp_entry_t entry)458 static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry)
459 {
460 	struct page *p = pfn_to_page(swp_offset_pfn(entry));
461 
462 	/*
463 	 * Any use of migration entries may only occur while the
464 	 * corresponding page is locked
465 	 */
466 	BUG_ON(is_migration_entry(entry) && !PageLocked(p));
467 
468 	return p;
469 }
470 
471 /*
472  * A pfn swap entry is a special type of swap entry that always has a pfn stored
473  * in the swap offset. They are used to represent unaddressable device memory
474  * and to restrict access to a page undergoing migration.
475  */
is_pfn_swap_entry(swp_entry_t entry)476 static inline bool is_pfn_swap_entry(swp_entry_t entry)
477 {
478 	/* Make sure the swp offset can always store the needed fields */
479 	BUILD_BUG_ON(SWP_TYPE_SHIFT < SWP_PFN_BITS);
480 
481 	return is_migration_entry(entry) || is_device_private_entry(entry) ||
482 	       is_device_exclusive_entry(entry);
483 }
484 
485 struct page_vma_mapped_walk;
486 
487 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
488 extern int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
489 		struct page *page);
490 
491 extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
492 		struct page *new);
493 
494 extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
495 
pmd_to_swp_entry(pmd_t pmd)496 static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
497 {
498 	swp_entry_t arch_entry;
499 
500 	if (pmd_swp_soft_dirty(pmd))
501 		pmd = pmd_swp_clear_soft_dirty(pmd);
502 	if (pmd_swp_uffd_wp(pmd))
503 		pmd = pmd_swp_clear_uffd_wp(pmd);
504 	arch_entry = __pmd_to_swp_entry(pmd);
505 	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
506 }
507 
swp_entry_to_pmd(swp_entry_t entry)508 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
509 {
510 	swp_entry_t arch_entry;
511 
512 	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
513 	return __swp_entry_to_pmd(arch_entry);
514 }
515 
is_pmd_migration_entry(pmd_t pmd)516 static inline int is_pmd_migration_entry(pmd_t pmd)
517 {
518 	return is_swap_pmd(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
519 }
520 #else  /* CONFIG_ARCH_ENABLE_THP_MIGRATION */
set_pmd_migration_entry(struct page_vma_mapped_walk * pvmw,struct page * page)521 static inline int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
522 		struct page *page)
523 {
524 	BUILD_BUG();
525 }
526 
remove_migration_pmd(struct page_vma_mapped_walk * pvmw,struct page * new)527 static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
528 		struct page *new)
529 {
530 	BUILD_BUG();
531 }
532 
pmd_migration_entry_wait(struct mm_struct * m,pmd_t * p)533 static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
534 
pmd_to_swp_entry(pmd_t pmd)535 static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
536 {
537 	return swp_entry(0, 0);
538 }
539 
swp_entry_to_pmd(swp_entry_t entry)540 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
541 {
542 	return __pmd(0);
543 }
544 
is_pmd_migration_entry(pmd_t pmd)545 static inline int is_pmd_migration_entry(pmd_t pmd)
546 {
547 	return 0;
548 }
549 #endif  /* CONFIG_ARCH_ENABLE_THP_MIGRATION */
550 
551 #ifdef CONFIG_MEMORY_FAILURE
552 
553 /*
554  * Support for hardware poisoned pages
555  */
make_hwpoison_entry(struct page * page)556 static inline swp_entry_t make_hwpoison_entry(struct page *page)
557 {
558 	BUG_ON(!PageLocked(page));
559 	return swp_entry(SWP_HWPOISON, page_to_pfn(page));
560 }
561 
is_hwpoison_entry(swp_entry_t entry)562 static inline int is_hwpoison_entry(swp_entry_t entry)
563 {
564 	return swp_type(entry) == SWP_HWPOISON;
565 }
566 
567 #else
568 
make_hwpoison_entry(struct page * page)569 static inline swp_entry_t make_hwpoison_entry(struct page *page)
570 {
571 	return swp_entry(0, 0);
572 }
573 
is_hwpoison_entry(swp_entry_t swp)574 static inline int is_hwpoison_entry(swp_entry_t swp)
575 {
576 	return 0;
577 }
578 #endif
579 
non_swap_entry(swp_entry_t entry)580 static inline int non_swap_entry(swp_entry_t entry)
581 {
582 	return swp_type(entry) >= MAX_SWAPFILES;
583 }
584 
585 #endif /* CONFIG_MMU */
586 #endif /* _LINUX_SWAPOPS_H */
587