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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#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 seven
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 two bits: 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/*
27 * Store a type+offset into a swp_entry_t in an arch-independent format
28 */
29static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
30{
31 swp_entry_t ret;
32
33 ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);
34 return ret;
35}
36
37/*
38 * Extract the `type' field from a swp_entry_t. The swp_entry_t is in
39 * arch-independent format
40 */
41static inline unsigned swp_type(swp_entry_t entry)
42{
43 return (entry.val >> SWP_TYPE_SHIFT);
44}
45
46/*
47 * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
48 * arch-independent format
49 */
50static inline pgoff_t swp_offset(swp_entry_t entry)
51{
52 return entry.val & SWP_OFFSET_MASK;
53}
54
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
61/*
62 * Convert the arch-dependent pte representation of a swp_entry_t into an
63 * arch-independent swp_entry_t.
64 */
65static inline swp_entry_t pte_to_swp_entry(pte_t pte)
66{
67 swp_entry_t arch_entry;
68
69 if (pte_swp_soft_dirty(pte))
70 pte = pte_swp_clear_soft_dirty(pte);
71 arch_entry = __pte_to_swp_entry(pte);
72 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
73}
74
75/*
76 * Convert the arch-independent representation of a swp_entry_t into the
77 * arch-dependent pte representation.
78 */
79static inline pte_t swp_entry_to_pte(swp_entry_t entry)
80{
81 swp_entry_t arch_entry;
82
83 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
84 return __swp_entry_to_pte(arch_entry);
85}
86
87static inline swp_entry_t radix_to_swp_entry(void *arg)
88{
89 swp_entry_t entry;
90
91 entry.val = xa_to_value(arg);
92 return entry;
93}
94
95static inline void *swp_to_radix_entry(swp_entry_t entry)
96{
97 return xa_mk_value(entry.val);
98}
99
100#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
101static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
102{
103 return swp_entry(write ? SWP_DEVICE_WRITE : SWP_DEVICE_READ,
104 page_to_pfn(page));
105}
106
107static inline bool is_device_private_entry(swp_entry_t entry)
108{
109 int type = swp_type(entry);
110 return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
111}
112
113static inline void make_device_private_entry_read(swp_entry_t *entry)
114{
115 *entry = swp_entry(SWP_DEVICE_READ, swp_offset(*entry));
116}
117
118static inline bool is_write_device_private_entry(swp_entry_t entry)
119{
120 return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
121}
122
123static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
124{
125 return swp_offset(entry);
126}
127
128static inline struct page *device_private_entry_to_page(swp_entry_t entry)
129{
130 return pfn_to_page(swp_offset(entry));
131}
132#else /* CONFIG_DEVICE_PRIVATE */
133static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
134{
135 return swp_entry(0, 0);
136}
137
138static inline void make_device_private_entry_read(swp_entry_t *entry)
139{
140}
141
142static inline bool is_device_private_entry(swp_entry_t entry)
143{
144 return false;
145}
146
147static inline bool is_write_device_private_entry(swp_entry_t entry)
148{
149 return false;
150}
151
152static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
153{
154 return 0;
155}
156
157static inline struct page *device_private_entry_to_page(swp_entry_t entry)
158{
159 return NULL;
160}
161#endif /* CONFIG_DEVICE_PRIVATE */
162
163#ifdef CONFIG_MIGRATION
164static inline swp_entry_t make_migration_entry(struct page *page, int write)
165{
166 BUG_ON(!PageLocked(compound_head(page)));
167
168 return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
169 page_to_pfn(page));
170}
171
172static inline int is_migration_entry(swp_entry_t entry)
173{
174 return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
175 swp_type(entry) == SWP_MIGRATION_WRITE);
176}
177
178static inline int is_write_migration_entry(swp_entry_t entry)
179{
180 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
181}
182
183static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
184{
185 return swp_offset(entry);
186}
187
188static inline struct page *migration_entry_to_page(swp_entry_t entry)
189{
190 struct page *p = pfn_to_page(swp_offset(entry));
191 /*
192 * Any use of migration entries may only occur while the
193 * corresponding page is locked
194 */
195 BUG_ON(!PageLocked(compound_head(p)));
196 return p;
197}
198
199static inline void make_migration_entry_read(swp_entry_t *entry)
200{
201 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
202}
203
204extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
205 spinlock_t *ptl);
206extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
207 unsigned long address);
208extern void migration_entry_wait_huge(struct vm_area_struct *vma,
209 struct mm_struct *mm, pte_t *pte);
210#else
211
212#define make_migration_entry(page, write) swp_entry(0, 0)
213static inline int is_migration_entry(swp_entry_t swp)
214{
215 return 0;
216}
217
218static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
219{
220 return 0;
221}
222
223static inline struct page *migration_entry_to_page(swp_entry_t entry)
224{
225 return NULL;
226}
227
228static inline void make_migration_entry_read(swp_entry_t *entryp) { }
229static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
230 spinlock_t *ptl) { }
231static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
232 unsigned long address) { }
233static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
234 struct mm_struct *mm, pte_t *pte) { }
235static inline int is_write_migration_entry(swp_entry_t entry)
236{
237 return 0;
238}
239
240#endif
241
242struct page_vma_mapped_walk;
243
244#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
245extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
246 struct page *page);
247
248extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
249 struct page *new);
250
251extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
252
253static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
254{
255 swp_entry_t arch_entry;
256
257 if (pmd_swp_soft_dirty(pmd))
258 pmd = pmd_swp_clear_soft_dirty(pmd);
259 arch_entry = __pmd_to_swp_entry(pmd);
260 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
261}
262
263static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
264{
265 swp_entry_t arch_entry;
266
267 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
268 return __swp_entry_to_pmd(arch_entry);
269}
270
271static inline int is_pmd_migration_entry(pmd_t pmd)
272{
273 return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
274}
275#else
276static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
277 struct page *page)
278{
279 BUILD_BUG();
280}
281
282static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
283 struct page *new)
284{
285 BUILD_BUG();
286}
287
288static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
289
290static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
291{
292 return swp_entry(0, 0);
293}
294
295static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
296{
297 return __pmd(0);
298}
299
300static inline int is_pmd_migration_entry(pmd_t pmd)
301{
302 return 0;
303}
304#endif
305
306#ifdef CONFIG_MEMORY_FAILURE
307
308extern atomic_long_t num_poisoned_pages __read_mostly;
309
310/*
311 * Support for hardware poisoned pages
312 */
313static inline swp_entry_t make_hwpoison_entry(struct page *page)
314{
315 BUG_ON(!PageLocked(page));
316 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
317}
318
319static inline int is_hwpoison_entry(swp_entry_t entry)
320{
321 return swp_type(entry) == SWP_HWPOISON;
322}
323
324static inline void num_poisoned_pages_inc(void)
325{
326 atomic_long_inc(&num_poisoned_pages);
327}
328
329static inline void num_poisoned_pages_dec(void)
330{
331 atomic_long_dec(&num_poisoned_pages);
332}
333
334#else
335
336static inline swp_entry_t make_hwpoison_entry(struct page *page)
337{
338 return swp_entry(0, 0);
339}
340
341static inline int is_hwpoison_entry(swp_entry_t swp)
342{
343 return 0;
344}
345
346static inline void num_poisoned_pages_inc(void)
347{
348}
349#endif
350
351#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
352static inline int non_swap_entry(swp_entry_t entry)
353{
354 return swp_type(entry) >= MAX_SWAPFILES;
355}
356#else
357static inline int non_swap_entry(swp_entry_t entry)
358{
359 return 0;
360}
361#endif
362
363#endif /* CONFIG_MMU */
364#endif /* _LINUX_SWAPOPS_H */