xref: /linux-6.15/include/linux/swapops.h (revision f6bcbf2e) 
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 
8 /*
9  * swapcache pages are stored in the swapper_space radix tree.  We want to
10  * get good packing density in that tree, so the index should be dense in
11  * the low-order bits.
12  *
13  * We arrange the `type' and `offset' fields so that `type' is at the seven
14  * high-order bits of the swp_entry_t and `offset' is right-aligned in the
15  * remaining bits.  Although `type' itself needs only five bits, we allow for
16  * shmem/tmpfs to shift it all up a further two bits: see swp_to_radix_entry().
17  *
18  * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
19  */
20 #define SWP_TYPE_SHIFT(e)	((sizeof(e.val) * 8) - \
21 			(MAX_SWAPFILES_SHIFT + RADIX_TREE_EXCEPTIONAL_SHIFT))
22 #define SWP_OFFSET_MASK(e)	((1UL << SWP_TYPE_SHIFT(e)) - 1)
23 
24 /*
25  * Store a type+offset into a swp_entry_t in an arch-independent format
26  */
27 static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
28 {
29 	swp_entry_t ret;
30 
31 	ret.val = (type << SWP_TYPE_SHIFT(ret)) |
32 			(offset & SWP_OFFSET_MASK(ret));
33 	return ret;
34 }
35 
36 /*
37  * Extract the `type' field from a swp_entry_t.  The swp_entry_t is in
38  * arch-independent format
39  */
40 static inline unsigned swp_type(swp_entry_t entry)
41 {
42 	return (entry.val >> SWP_TYPE_SHIFT(entry));
43 }
44 
45 /*
46  * Extract the `offset' field from a swp_entry_t.  The swp_entry_t is in
47  * arch-independent format
48  */
49 static inline pgoff_t swp_offset(swp_entry_t entry)
50 {
51 	return entry.val & SWP_OFFSET_MASK(entry);
52 }
53 
54 #ifdef CONFIG_MMU
55 /* check whether a pte points to a swap entry */
56 static inline int is_swap_pte(pte_t pte)
57 {
58 	return !pte_none(pte) && !pte_present(pte);
59 }
60 #endif
61 
62 /*
63  * Convert the arch-dependent pte representation of a swp_entry_t into an
64  * arch-independent swp_entry_t.
65  */
66 static inline swp_entry_t pte_to_swp_entry(pte_t pte)
67 {
68 	swp_entry_t arch_entry;
69 
70 	if (pte_swp_soft_dirty(pte))
71 		pte = pte_swp_clear_soft_dirty(pte);
72 	arch_entry = __pte_to_swp_entry(pte);
73 	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
74 }
75 
76 /*
77  * Convert the arch-independent representation of a swp_entry_t into the
78  * arch-dependent pte representation.
79  */
80 static inline pte_t swp_entry_to_pte(swp_entry_t entry)
81 {
82 	swp_entry_t arch_entry;
83 
84 	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
85 	return __swp_entry_to_pte(arch_entry);
86 }
87 
88 static inline swp_entry_t radix_to_swp_entry(void *arg)
89 {
90 	swp_entry_t entry;
91 
92 	entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
93 	return entry;
94 }
95 
96 static inline void *swp_to_radix_entry(swp_entry_t entry)
97 {
98 	unsigned long value;
99 
100 	value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
101 	return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
102 }
103 
104 #if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
105 static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
106 {
107 	return swp_entry(write ? SWP_DEVICE_WRITE : SWP_DEVICE_READ,
108 			 page_to_pfn(page));
109 }
110 
111 static inline bool is_device_private_entry(swp_entry_t entry)
112 {
113 	int type = swp_type(entry);
114 	return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
115 }
116 
117 static inline void make_device_private_entry_read(swp_entry_t *entry)
118 {
119 	*entry = swp_entry(SWP_DEVICE_READ, swp_offset(*entry));
120 }
121 
122 static inline bool is_write_device_private_entry(swp_entry_t entry)
123 {
124 	return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
125 }
126 
127 static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
128 {
129 	return swp_offset(entry);
130 }
131 
132 static inline struct page *device_private_entry_to_page(swp_entry_t entry)
133 {
134 	return pfn_to_page(swp_offset(entry));
135 }
136 
137 int device_private_entry_fault(struct vm_area_struct *vma,
138 		       unsigned long addr,
139 		       swp_entry_t entry,
140 		       unsigned int flags,
141 		       pmd_t *pmdp);
142 #else /* CONFIG_DEVICE_PRIVATE */
143 static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
144 {
145 	return swp_entry(0, 0);
146 }
147 
148 static inline void make_device_private_entry_read(swp_entry_t *entry)
149 {
150 }
151 
152 static inline bool is_device_private_entry(swp_entry_t entry)
153 {
154 	return false;
155 }
156 
157 static inline bool is_write_device_private_entry(swp_entry_t entry)
158 {
159 	return false;
160 }
161 
162 static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
163 {
164 	return 0;
165 }
166 
167 static inline struct page *device_private_entry_to_page(swp_entry_t entry)
168 {
169 	return NULL;
170 }
171 
172 static inline int device_private_entry_fault(struct vm_area_struct *vma,
173 				     unsigned long addr,
174 				     swp_entry_t entry,
175 				     unsigned int flags,
176 				     pmd_t *pmdp)
177 {
178 	return VM_FAULT_SIGBUS;
179 }
180 #endif /* CONFIG_DEVICE_PRIVATE */
181 
182 #ifdef CONFIG_MIGRATION
183 static inline swp_entry_t make_migration_entry(struct page *page, int write)
184 {
185 	BUG_ON(!PageLocked(compound_head(page)));
186 
187 	return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
188 			page_to_pfn(page));
189 }
190 
191 static inline int is_migration_entry(swp_entry_t entry)
192 {
193 	return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
194 			swp_type(entry) == SWP_MIGRATION_WRITE);
195 }
196 
197 static inline int is_write_migration_entry(swp_entry_t entry)
198 {
199 	return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
200 }
201 
202 static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
203 {
204 	return swp_offset(entry);
205 }
206 
207 static inline struct page *migration_entry_to_page(swp_entry_t entry)
208 {
209 	struct page *p = pfn_to_page(swp_offset(entry));
210 	/*
211 	 * Any use of migration entries may only occur while the
212 	 * corresponding page is locked
213 	 */
214 	BUG_ON(!PageLocked(compound_head(p)));
215 	return p;
216 }
217 
218 static inline void make_migration_entry_read(swp_entry_t *entry)
219 {
220 	*entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
221 }
222 
223 extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
224 					spinlock_t *ptl);
225 extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
226 					unsigned long address);
227 extern void migration_entry_wait_huge(struct vm_area_struct *vma,
228 		struct mm_struct *mm, pte_t *pte);
229 #else
230 
231 #define make_migration_entry(page, write) swp_entry(0, 0)
232 static inline int is_migration_entry(swp_entry_t swp)
233 {
234 	return 0;
235 }
236 
237 static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
238 {
239 	return 0;
240 }
241 
242 static inline struct page *migration_entry_to_page(swp_entry_t entry)
243 {
244 	return NULL;
245 }
246 
247 static inline void make_migration_entry_read(swp_entry_t *entryp) { }
248 static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
249 					spinlock_t *ptl) { }
250 static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
251 					 unsigned long address) { }
252 static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
253 		struct mm_struct *mm, pte_t *pte) { }
254 static inline int is_write_migration_entry(swp_entry_t entry)
255 {
256 	return 0;
257 }
258 
259 #endif
260 
261 struct page_vma_mapped_walk;
262 
263 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
264 extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
265 		struct page *page);
266 
267 extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
268 		struct page *new);
269 
270 extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
271 
272 static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
273 {
274 	swp_entry_t arch_entry;
275 
276 	if (pmd_swp_soft_dirty(pmd))
277 		pmd = pmd_swp_clear_soft_dirty(pmd);
278 	arch_entry = __pmd_to_swp_entry(pmd);
279 	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
280 }
281 
282 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
283 {
284 	swp_entry_t arch_entry;
285 
286 	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
287 	return __swp_entry_to_pmd(arch_entry);
288 }
289 
290 static inline int is_pmd_migration_entry(pmd_t pmd)
291 {
292 	return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
293 }
294 #else
295 static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
296 		struct page *page)
297 {
298 	BUILD_BUG();
299 }
300 
301 static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
302 		struct page *new)
303 {
304 	BUILD_BUG();
305 }
306 
307 static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
308 
309 static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
310 {
311 	return swp_entry(0, 0);
312 }
313 
314 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
315 {
316 	return __pmd(0);
317 }
318 
319 static inline int is_pmd_migration_entry(pmd_t pmd)
320 {
321 	return 0;
322 }
323 #endif
324 
325 #ifdef CONFIG_MEMORY_FAILURE
326 
327 extern atomic_long_t num_poisoned_pages __read_mostly;
328 
329 /*
330  * Support for hardware poisoned pages
331  */
332 static inline swp_entry_t make_hwpoison_entry(struct page *page)
333 {
334 	BUG_ON(!PageLocked(page));
335 	return swp_entry(SWP_HWPOISON, page_to_pfn(page));
336 }
337 
338 static inline int is_hwpoison_entry(swp_entry_t entry)
339 {
340 	return swp_type(entry) == SWP_HWPOISON;
341 }
342 
343 static inline bool test_set_page_hwpoison(struct page *page)
344 {
345 	return TestSetPageHWPoison(page);
346 }
347 
348 static inline void num_poisoned_pages_inc(void)
349 {
350 	atomic_long_inc(&num_poisoned_pages);
351 }
352 
353 static inline void num_poisoned_pages_dec(void)
354 {
355 	atomic_long_dec(&num_poisoned_pages);
356 }
357 
358 #else
359 
360 static inline swp_entry_t make_hwpoison_entry(struct page *page)
361 {
362 	return swp_entry(0, 0);
363 }
364 
365 static inline int is_hwpoison_entry(swp_entry_t swp)
366 {
367 	return 0;
368 }
369 
370 static inline bool test_set_page_hwpoison(struct page *page)
371 {
372 	return false;
373 }
374 
375 static inline void num_poisoned_pages_inc(void)
376 {
377 }
378 #endif
379 
380 #if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
381 static inline int non_swap_entry(swp_entry_t entry)
382 {
383 	return swp_type(entry) >= MAX_SWAPFILES;
384 }
385 #else
386 static inline int non_swap_entry(swp_entry_t entry)
387 {
388 	return 0;
389 }
390 #endif
391 
392 #endif /* _LINUX_SWAPOPS_H */
393