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1#ifndef _LINUX_SWAPOPS_H
2#define _LINUX_SWAPOPS_H
3
4#include <linux/radix-tree.h>
5#include <linux/bug.h>
6
7/*
8 * swapcache pages are stored in the swapper_space radix tree. We want to
9 * get good packing density in that tree, so the index should be dense in
10 * the low-order bits.
11 *
12 * We arrange the `type' and `offset' fields so that `type' is at the seven
13 * high-order bits of the swp_entry_t and `offset' is right-aligned in the
14 * remaining bits. Although `type' itself needs only five bits, we allow for
15 * shmem/tmpfs to shift it all up a further two bits: see swp_to_radix_entry().
16 *
17 * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
18 */
19#define SWP_TYPE_SHIFT(e) ((sizeof(e.val) * 8) - \
20 (MAX_SWAPFILES_SHIFT + RADIX_TREE_EXCEPTIONAL_SHIFT))
21#define SWP_OFFSET_MASK(e) ((1UL << SWP_TYPE_SHIFT(e)) - 1)
22
23/*
24 * Store a type+offset into a swp_entry_t in an arch-independent format
25 */
26static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
27{
28 swp_entry_t ret;
29
30 ret.val = (type << SWP_TYPE_SHIFT(ret)) |
31 (offset & SWP_OFFSET_MASK(ret));
32 return ret;
33}
34
35/*
36 * Extract the `type' field from a swp_entry_t. The swp_entry_t is in
37 * arch-independent format
38 */
39static inline unsigned swp_type(swp_entry_t entry)
40{
41 return (entry.val >> SWP_TYPE_SHIFT(entry));
42}
43
44/*
45 * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
46 * arch-independent format
47 */
48static inline pgoff_t swp_offset(swp_entry_t entry)
49{
50 return entry.val & SWP_OFFSET_MASK(entry);
51}
52
53#ifdef CONFIG_MMU
54/* check whether a pte points to a swap entry */
55static inline int is_swap_pte(pte_t pte)
56{
57 return !pte_none(pte) && !pte_present(pte);
58}
59#endif
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 = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
92 return entry;
93}
94
95static inline void *swp_to_radix_entry(swp_entry_t entry)
96{
97 unsigned long value;
98
99 value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
100 return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
101}
102
103#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
104static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
105{
106 return swp_entry(write ? SWP_DEVICE_WRITE : SWP_DEVICE_READ,
107 page_to_pfn(page));
108}
109
110static inline bool is_device_private_entry(swp_entry_t entry)
111{
112 int type = swp_type(entry);
113 return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
114}
115
116static inline void make_device_private_entry_read(swp_entry_t *entry)
117{
118 *entry = swp_entry(SWP_DEVICE_READ, swp_offset(*entry));
119}
120
121static inline bool is_write_device_private_entry(swp_entry_t entry)
122{
123 return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
124}
125
126static inline struct page *device_private_entry_to_page(swp_entry_t entry)
127{
128 return pfn_to_page(swp_offset(entry));
129}
130
131int device_private_entry_fault(struct vm_area_struct *vma,
132 unsigned long addr,
133 swp_entry_t entry,
134 unsigned int flags,
135 pmd_t *pmdp);
136#else /* CONFIG_DEVICE_PRIVATE */
137static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
138{
139 return swp_entry(0, 0);
140}
141
142static inline void make_device_private_entry_read(swp_entry_t *entry)
143{
144}
145
146static inline bool is_device_private_entry(swp_entry_t entry)
147{
148 return false;
149}
150
151static inline bool is_write_device_private_entry(swp_entry_t entry)
152{
153 return false;
154}
155
156static inline struct page *device_private_entry_to_page(swp_entry_t entry)
157{
158 return NULL;
159}
160
161static inline int device_private_entry_fault(struct vm_area_struct *vma,
162 unsigned long addr,
163 swp_entry_t entry,
164 unsigned int flags,
165 pmd_t *pmdp)
166{
167 return VM_FAULT_SIGBUS;
168}
169#endif /* CONFIG_DEVICE_PRIVATE */
170
171#ifdef CONFIG_MIGRATION
172static inline swp_entry_t make_migration_entry(struct page *page, int write)
173{
174 BUG_ON(!PageLocked(compound_head(page)));
175
176 return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
177 page_to_pfn(page));
178}
179
180static inline int is_migration_entry(swp_entry_t entry)
181{
182 return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
183 swp_type(entry) == SWP_MIGRATION_WRITE);
184}
185
186static inline int is_write_migration_entry(swp_entry_t entry)
187{
188 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
189}
190
191static inline struct page *migration_entry_to_page(swp_entry_t entry)
192{
193 struct page *p = pfn_to_page(swp_offset(entry));
194 /*
195 * Any use of migration entries may only occur while the
196 * corresponding page is locked
197 */
198 BUG_ON(!PageLocked(compound_head(p)));
199 return p;
200}
201
202static inline void make_migration_entry_read(swp_entry_t *entry)
203{
204 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
205}
206
207extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
208 spinlock_t *ptl);
209extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
210 unsigned long address);
211extern void migration_entry_wait_huge(struct vm_area_struct *vma,
212 struct mm_struct *mm, pte_t *pte);
213#else
214
215#define make_migration_entry(page, write) swp_entry(0, 0)
216static inline int is_migration_entry(swp_entry_t swp)
217{
218 return 0;
219}
220static inline struct page *migration_entry_to_page(swp_entry_t entry)
221{
222 return NULL;
223}
224
225static inline void make_migration_entry_read(swp_entry_t *entryp) { }
226static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
227 spinlock_t *ptl) { }
228static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
229 unsigned long address) { }
230static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
231 struct mm_struct *mm, pte_t *pte) { }
232static inline int is_write_migration_entry(swp_entry_t entry)
233{
234 return 0;
235}
236
237#endif
238
239struct page_vma_mapped_walk;
240
241#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
242extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
243 struct page *page);
244
245extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
246 struct page *new);
247
248extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
249
250static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
251{
252 swp_entry_t arch_entry;
253
254 if (pmd_swp_soft_dirty(pmd))
255 pmd = pmd_swp_clear_soft_dirty(pmd);
256 arch_entry = __pmd_to_swp_entry(pmd);
257 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
258}
259
260static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
261{
262 swp_entry_t arch_entry;
263
264 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
265 return __swp_entry_to_pmd(arch_entry);
266}
267
268static inline int is_pmd_migration_entry(pmd_t pmd)
269{
270 return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
271}
272#else
273static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
274 struct page *page)
275{
276 BUILD_BUG();
277}
278
279static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
280 struct page *new)
281{
282 BUILD_BUG();
283}
284
285static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
286
287static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
288{
289 return swp_entry(0, 0);
290}
291
292static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
293{
294 return __pmd(0);
295}
296
297static inline int is_pmd_migration_entry(pmd_t pmd)
298{
299 return 0;
300}
301#endif
302
303#ifdef CONFIG_MEMORY_FAILURE
304
305extern atomic_long_t num_poisoned_pages __read_mostly;
306
307/*
308 * Support for hardware poisoned pages
309 */
310static inline swp_entry_t make_hwpoison_entry(struct page *page)
311{
312 BUG_ON(!PageLocked(page));
313 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
314}
315
316static inline int is_hwpoison_entry(swp_entry_t entry)
317{
318 return swp_type(entry) == SWP_HWPOISON;
319}
320
321static inline bool test_set_page_hwpoison(struct page *page)
322{
323 return TestSetPageHWPoison(page);
324}
325
326static inline void num_poisoned_pages_inc(void)
327{
328 atomic_long_inc(&num_poisoned_pages);
329}
330
331static inline void num_poisoned_pages_dec(void)
332{
333 atomic_long_dec(&num_poisoned_pages);
334}
335
336#else
337
338static inline swp_entry_t make_hwpoison_entry(struct page *page)
339{
340 return swp_entry(0, 0);
341}
342
343static inline int is_hwpoison_entry(swp_entry_t swp)
344{
345 return 0;
346}
347
348static inline bool test_set_page_hwpoison(struct page *page)
349{
350 return false;
351}
352
353static inline void num_poisoned_pages_inc(void)
354{
355}
356#endif
357
358#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
359static inline int non_swap_entry(swp_entry_t entry)
360{
361 return swp_type(entry) >= MAX_SWAPFILES;
362}
363#else
364static inline int non_swap_entry(swp_entry_t entry)
365{
366 return 0;
367}
368#endif
369
370#endif /* _LINUX_SWAPOPS_H */