1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SWAPOPS_H
3 #define _LINUX_SWAPOPS_H
5 #include <linux/radix-tree.h>
7 #include <linux/mm_types.h>
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
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().
21 * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
23 #define SWP_TYPE_SHIFT (BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT)
24 #define SWP_OFFSET_MASK ((1UL << SWP_TYPE_SHIFT) - 1)
26 /* Clear all flags but only keep swp_entry_t related information */
27 static inline pte_t pte_swp_clear_flags(pte_t pte)
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);
37 * Store a type+offset into a swp_entry_t in an arch-independent format
39 static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
43 ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);
48 * Extract the `type' field from a swp_entry_t. The swp_entry_t is in
49 * arch-independent format
51 static inline unsigned swp_type(swp_entry_t entry)
53 return (entry.val >> SWP_TYPE_SHIFT);
57 * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
58 * arch-independent format
60 static inline pgoff_t swp_offset(swp_entry_t entry)
62 return entry.val & SWP_OFFSET_MASK;
65 /* check whether a pte points to a swap entry */
66 static inline int is_swap_pte(pte_t pte)
68 return !pte_none(pte) && !pte_present(pte);
72 * Convert the arch-dependent pte representation of a swp_entry_t into an
73 * arch-independent swp_entry_t.
75 static inline swp_entry_t pte_to_swp_entry(pte_t pte)
77 swp_entry_t arch_entry;
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));
85 * Convert the arch-independent representation of a swp_entry_t into the
86 * arch-dependent pte representation.
88 static inline pte_t swp_entry_to_pte(swp_entry_t entry)
90 swp_entry_t arch_entry;
92 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
93 return __swp_entry_to_pte(arch_entry);
96 static inline swp_entry_t radix_to_swp_entry(void *arg)
100 entry.val = xa_to_value(arg);
104 static inline void *swp_to_radix_entry(swp_entry_t entry)
106 return xa_mk_value(entry.val);
109 #if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
110 static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
112 return swp_entry(SWP_DEVICE_READ, offset);
115 static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
117 return swp_entry(SWP_DEVICE_WRITE, offset);
120 static inline bool is_device_private_entry(swp_entry_t entry)
122 int type = swp_type(entry);
123 return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
126 static inline bool is_writable_device_private_entry(swp_entry_t entry)
128 return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
130 #else /* CONFIG_DEVICE_PRIVATE */
131 static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset)
133 return swp_entry(0, 0);
136 static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset)
138 return swp_entry(0, 0);
141 static inline bool is_device_private_entry(swp_entry_t entry)
146 static inline bool is_writable_device_private_entry(swp_entry_t entry)
150 #endif /* CONFIG_DEVICE_PRIVATE */
152 #ifdef CONFIG_MIGRATION
153 static inline int is_migration_entry(swp_entry_t entry)
155 return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
156 swp_type(entry) == SWP_MIGRATION_WRITE);
159 static inline int is_writable_migration_entry(swp_entry_t entry)
161 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
164 static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
166 return swp_entry(SWP_MIGRATION_READ, offset);
169 static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
171 return swp_entry(SWP_MIGRATION_WRITE, offset);
174 extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
176 extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
177 unsigned long address);
178 extern void migration_entry_wait_huge(struct vm_area_struct *vma,
179 struct mm_struct *mm, pte_t *pte);
181 static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
183 return swp_entry(0, 0);
186 static inline swp_entry_t make_writable_migration_entry(pgoff_t offset)
188 return swp_entry(0, 0);
191 static inline int is_migration_entry(swp_entry_t swp)
196 static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
198 static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
199 unsigned long address) { }
200 static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
201 struct mm_struct *mm, pte_t *pte) { }
202 static inline int is_writable_migration_entry(swp_entry_t entry)
209 static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry)
211 struct page *p = pfn_to_page(swp_offset(entry));
214 * Any use of migration entries may only occur while the
215 * corresponding page is locked
217 BUG_ON(is_migration_entry(entry) && !PageLocked(p));
223 * A pfn swap entry is a special type of swap entry that always has a pfn stored
224 * in the swap offset. They are used to represent unaddressable device memory
225 * and to restrict access to a page undergoing migration.
227 static inline bool is_pfn_swap_entry(swp_entry_t entry)
229 return is_migration_entry(entry) || is_device_private_entry(entry);
232 struct page_vma_mapped_walk;
234 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
235 extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
238 extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
241 extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
243 static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
245 swp_entry_t arch_entry;
247 if (pmd_swp_soft_dirty(pmd))
248 pmd = pmd_swp_clear_soft_dirty(pmd);
249 if (pmd_swp_uffd_wp(pmd))
250 pmd = pmd_swp_clear_uffd_wp(pmd);
251 arch_entry = __pmd_to_swp_entry(pmd);
252 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
255 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
257 swp_entry_t arch_entry;
259 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
260 return __swp_entry_to_pmd(arch_entry);
263 static inline int is_pmd_migration_entry(pmd_t pmd)
265 return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
268 static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
274 static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
280 static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
282 static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
284 return swp_entry(0, 0);
287 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
292 static inline int is_pmd_migration_entry(pmd_t pmd)
298 #ifdef CONFIG_MEMORY_FAILURE
300 extern atomic_long_t num_poisoned_pages __read_mostly;
303 * Support for hardware poisoned pages
305 static inline swp_entry_t make_hwpoison_entry(struct page *page)
307 BUG_ON(!PageLocked(page));
308 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
311 static inline int is_hwpoison_entry(swp_entry_t entry)
313 return swp_type(entry) == SWP_HWPOISON;
316 static inline unsigned long hwpoison_entry_to_pfn(swp_entry_t entry)
318 return swp_offset(entry);
321 static inline void num_poisoned_pages_inc(void)
323 atomic_long_inc(&num_poisoned_pages);
326 static inline void num_poisoned_pages_dec(void)
328 atomic_long_dec(&num_poisoned_pages);
333 static inline swp_entry_t make_hwpoison_entry(struct page *page)
335 return swp_entry(0, 0);
338 static inline int is_hwpoison_entry(swp_entry_t swp)
343 static inline void num_poisoned_pages_inc(void)
348 #if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) || \
349 defined(CONFIG_DEVICE_PRIVATE)
350 static inline int non_swap_entry(swp_entry_t entry)
352 return swp_type(entry) >= MAX_SWAPFILES;
355 static inline int non_swap_entry(swp_entry_t entry)
361 #endif /* CONFIG_MMU */
362 #endif /* _LINUX_SWAPOPS_H */