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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/* 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_soft_dirty(pte))
30 pte = pte_swp_clear_soft_dirty(pte);
31 if (pte_swp_uffd_wp(pte))
32 pte = pte_swp_clear_uffd_wp(pte);
33 return pte;
34}
35
36/*
37 * Store a type+offset into a swp_entry_t in an arch-independent format
38 */
39static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
40{
41 swp_entry_t ret;
42
43 ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);
44 return ret;
45}
46
47/*
48 * Extract the `type' field from a swp_entry_t. The swp_entry_t is in
49 * arch-independent format
50 */
51static inline unsigned swp_type(swp_entry_t entry)
52{
53 return (entry.val >> SWP_TYPE_SHIFT);
54}
55
56/*
57 * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
58 * arch-independent format
59 */
60static inline pgoff_t swp_offset(swp_entry_t entry)
61{
62 return entry.val & SWP_OFFSET_MASK;
63}
64
65/* check whether a pte points to a swap entry */
66static inline int is_swap_pte(pte_t pte)
67{
68 return !pte_none(pte) && !pte_present(pte);
69}
70
71/*
72 * Convert the arch-dependent pte representation of a swp_entry_t into an
73 * arch-independent swp_entry_t.
74 */
75static inline swp_entry_t pte_to_swp_entry(pte_t pte)
76{
77 swp_entry_t arch_entry;
78
79 pte = pte_swp_clear_flags(pte);
80 arch_entry = __pte_to_swp_entry(pte);
81 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
82}
83
84/*
85 * Convert the arch-independent representation of a swp_entry_t into the
86 * arch-dependent pte representation.
87 */
88static inline pte_t swp_entry_to_pte(swp_entry_t entry)
89{
90 swp_entry_t arch_entry;
91
92 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
93 return __swp_entry_to_pte(arch_entry);
94}
95
96static inline swp_entry_t radix_to_swp_entry(void *arg)
97{
98 swp_entry_t entry;
99
100 entry.val = xa_to_value(arg);
101 return entry;
102}
103
104static inline void *swp_to_radix_entry(swp_entry_t entry)
105{
106 return xa_mk_value(entry.val);
107}
108
109#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
110static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
111{
112 return swp_entry(SWP_DEVICE_READ, offset);
113}
114
115static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
116{
117 return swp_entry(SWP_DEVICE_WRITE, offset);
118}
119
120static inline bool is_device_private_entry(swp_entry_t entry)
121{
122 int type = swp_type(entry);
123 return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
124}
125
126static inline bool is_writable_device_private_entry(swp_entry_t entry)
127{
128 return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
129}
130
131static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset)
132{
133 return swp_entry(SWP_DEVICE_EXCLUSIVE_READ, offset);
134}
135
136static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset)
137{
138 return swp_entry(SWP_DEVICE_EXCLUSIVE_WRITE, offset);
139}
140
141static inline bool is_device_exclusive_entry(swp_entry_t entry)
142{
143 return swp_type(entry) == SWP_DEVICE_EXCLUSIVE_READ ||
144 swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE;
145}
146
147static inline bool is_writable_device_exclusive_entry(swp_entry_t entry)
148{
149 return unlikely(swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE);
150}
151#else /* CONFIG_DEVICE_PRIVATE */
152static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
153{
154 return swp_entry(0, 0);
155}
156
157static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
158{
159 return swp_entry(0, 0);
160}
161
162static inline bool is_device_private_entry(swp_entry_t entry)
163{
164 return false;
165}
166
167static inline bool is_writable_device_private_entry(swp_entry_t entry)
168{
169 return false;
170}
171
172static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset)
173{
174 return swp_entry(0, 0);
175}
176
177static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset)
178{
179 return swp_entry(0, 0);
180}
181
182static inline bool is_device_exclusive_entry(swp_entry_t entry)
183{
184 return false;
185}
186
187static inline bool is_writable_device_exclusive_entry(swp_entry_t entry)
188{
189 return false;
190}
191#endif /* CONFIG_DEVICE_PRIVATE */
192
193#ifdef CONFIG_MIGRATION
194static inline int is_migration_entry(swp_entry_t entry)
195{
196 return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
197 swp_type(entry) == SWP_MIGRATION_WRITE);
198}
199
200static inline int is_writable_migration_entry(swp_entry_t entry)
201{
202 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
203}
204
205static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
206{
207 return swp_entry(SWP_MIGRATION_READ, offset);
208}
209
210static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
211{
212 return swp_entry(SWP_MIGRATION_WRITE, offset);
213}
214
215extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
216 spinlock_t *ptl);
217extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
218 unsigned long address);
219extern void migration_entry_wait_huge(struct vm_area_struct *vma,
220 struct mm_struct *mm, pte_t *pte);
221#else
222static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
223{
224 return swp_entry(0, 0);
225}
226
227static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
228{
229 return swp_entry(0, 0);
230}
231
232static inline int is_migration_entry(swp_entry_t swp)
233{
234 return 0;
235}
236
237static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
238 spinlock_t *ptl) { }
239static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
240 unsigned long address) { }
241static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
242 struct mm_struct *mm, pte_t *pte) { }
243static inline int is_writable_migration_entry(swp_entry_t entry)
244{
245 return 0;
246}
247
248#endif
249
250static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry)
251{
252 struct page *p = pfn_to_page(swp_offset(entry));
253
254 /*
255 * Any use of migration entries may only occur while the
256 * corresponding page is locked
257 */
258 BUG_ON(is_migration_entry(entry) && !PageLocked(p));
259
260 return p;
261}
262
263/*
264 * A pfn swap entry is a special type of swap entry that always has a pfn stored
265 * in the swap offset. They are used to represent unaddressable device memory
266 * and to restrict access to a page undergoing migration.
267 */
268static inline bool is_pfn_swap_entry(swp_entry_t entry)
269{
270 return is_migration_entry(entry) || is_device_private_entry(entry) ||
271 is_device_exclusive_entry(entry);
272}
273
274struct page_vma_mapped_walk;
275
276#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
277extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
278 struct page *page);
279
280extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
281 struct page *new);
282
283extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
284
285static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
286{
287 swp_entry_t arch_entry;
288
289 if (pmd_swp_soft_dirty(pmd))
290 pmd = pmd_swp_clear_soft_dirty(pmd);
291 if (pmd_swp_uffd_wp(pmd))
292 pmd = pmd_swp_clear_uffd_wp(pmd);
293 arch_entry = __pmd_to_swp_entry(pmd);
294 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
295}
296
297static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
298{
299 swp_entry_t arch_entry;
300
301 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
302 return __swp_entry_to_pmd(arch_entry);
303}
304
305static inline int is_pmd_migration_entry(pmd_t pmd)
306{
307 return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
308}
309#else
310static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
311 struct page *page)
312{
313 BUILD_BUG();
314}
315
316static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
317 struct page *new)
318{
319 BUILD_BUG();
320}
321
322static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
323
324static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
325{
326 return swp_entry(0, 0);
327}
328
329static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
330{
331 return __pmd(0);
332}
333
334static inline int is_pmd_migration_entry(pmd_t pmd)
335{
336 return 0;
337}
338#endif
339
340#ifdef CONFIG_MEMORY_FAILURE
341
342extern atomic_long_t num_poisoned_pages __read_mostly;
343
344/*
345 * Support for hardware poisoned pages
346 */
347static inline swp_entry_t make_hwpoison_entry(struct page *page)
348{
349 BUG_ON(!PageLocked(page));
350 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
351}
352
353static inline int is_hwpoison_entry(swp_entry_t entry)
354{
355 return swp_type(entry) == SWP_HWPOISON;
356}
357
358static inline unsigned long hwpoison_entry_to_pfn(swp_entry_t entry)
359{
360 return swp_offset(entry);
361}
362
363static inline void num_poisoned_pages_inc(void)
364{
365 atomic_long_inc(&num_poisoned_pages);
366}
367
368static inline void num_poisoned_pages_dec(void)
369{
370 atomic_long_dec(&num_poisoned_pages);
371}
372
373#else
374
375static inline swp_entry_t make_hwpoison_entry(struct page *page)
376{
377 return swp_entry(0, 0);
378}
379
380static inline int is_hwpoison_entry(swp_entry_t swp)
381{
382 return 0;
383}
384
385static inline void num_poisoned_pages_inc(void)
386{
387}
388#endif
389
390#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) || \
391 defined(CONFIG_DEVICE_PRIVATE)
392static inline int non_swap_entry(swp_entry_t entry)
393{
394 return swp_type(entry) >= MAX_SWAPFILES;
395}
396#else
397static inline int non_swap_entry(swp_entry_t entry)
398{
399 return 0;
400}
401#endif
402
403#endif /* CONFIG_MMU */
404#endif /* _LINUX_SWAPOPS_H */