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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 */
27static 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 */
40static 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 */
49static 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 */
56static 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 */
66static 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 */
80static 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
88static 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
96static 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)
105static 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
111static 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
117static inline void make_device_private_entry_read(swp_entry_t *entry)
118{
119 *entry = swp_entry(SWP_DEVICE_READ, swp_offset(*entry));
120}
121
122static inline bool is_write_device_private_entry(swp_entry_t entry)
123{
124 return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
125}
126
127static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
128{
129 return swp_offset(entry);
130}
131
132static inline struct page *device_private_entry_to_page(swp_entry_t entry)
133{
134 return pfn_to_page(swp_offset(entry));
135}
136
137int 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 */
143static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
144{
145 return swp_entry(0, 0);
146}
147
148static inline void make_device_private_entry_read(swp_entry_t *entry)
149{
150}
151
152static inline bool is_device_private_entry(swp_entry_t entry)
153{
154 return false;
155}
156
157static inline bool is_write_device_private_entry(swp_entry_t entry)
158{
159 return false;
160}
161
162static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
163{
164 return 0;
165}
166
167static inline struct page *device_private_entry_to_page(swp_entry_t entry)
168{
169 return NULL;
170}
171
172static 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
183static 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
191static 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
197static inline int is_write_migration_entry(swp_entry_t entry)
198{
199 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
200}
201
202static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
203{
204 return swp_offset(entry);
205}
206
207static 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
218static inline void make_migration_entry_read(swp_entry_t *entry)
219{
220 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
221}
222
223extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
224 spinlock_t *ptl);
225extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
226 unsigned long address);
227extern 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)
232static inline int is_migration_entry(swp_entry_t swp)
233{
234 return 0;
235}
236
237static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
238{
239 return 0;
240}
241
242static inline struct page *migration_entry_to_page(swp_entry_t entry)
243{
244 return NULL;
245}
246
247static inline void make_migration_entry_read(swp_entry_t *entryp) { }
248static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
249 spinlock_t *ptl) { }
250static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
251 unsigned long address) { }
252static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
253 struct mm_struct *mm, pte_t *pte) { }
254static inline int is_write_migration_entry(swp_entry_t entry)
255{
256 return 0;
257}
258
259#endif
260
261struct page_vma_mapped_walk;
262
263#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
264extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
265 struct page *page);
266
267extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
268 struct page *new);
269
270extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
271
272static 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
282static 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
290static 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
295static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
296 struct page *page)
297{
298 BUILD_BUG();
299}
300
301static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
302 struct page *new)
303{
304 BUILD_BUG();
305}
306
307static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
308
309static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
310{
311 return swp_entry(0, 0);
312}
313
314static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
315{
316 return __pmd(0);
317}
318
319static inline int is_pmd_migration_entry(pmd_t pmd)
320{
321 return 0;
322}
323#endif
324
325#ifdef CONFIG_MEMORY_FAILURE
326
327extern atomic_long_t num_poisoned_pages __read_mostly;
328
329/*
330 * Support for hardware poisoned pages
331 */
332static 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
338static inline int is_hwpoison_entry(swp_entry_t entry)
339{
340 return swp_type(entry) == SWP_HWPOISON;
341}
342
343static inline bool test_set_page_hwpoison(struct page *page)
344{
345 return TestSetPageHWPoison(page);
346}
347
348static inline void num_poisoned_pages_inc(void)
349{
350 atomic_long_inc(&num_poisoned_pages);
351}
352
353static inline void num_poisoned_pages_dec(void)
354{
355 atomic_long_dec(&num_poisoned_pages);
356}
357
358#else
359
360static inline swp_entry_t make_hwpoison_entry(struct page *page)
361{
362 return swp_entry(0, 0);
363}
364
365static inline int is_hwpoison_entry(swp_entry_t swp)
366{
367 return 0;
368}
369
370static inline bool test_set_page_hwpoison(struct page *page)
371{
372 return false;
373}
374
375static inline void num_poisoned_pages_inc(void)
376{
377}
378#endif
379
380#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
381static inline int non_swap_entry(swp_entry_t entry)
382{
383 return swp_type(entry) >= MAX_SWAPFILES;
384}
385#else
386static inline int non_swap_entry(swp_entry_t entry)
387{
388 return 0;
389}
390#endif
391
392#endif /* _LINUX_SWAPOPS_H */