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 */ 26 static 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 */ 39 static 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 */ 48 static 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 */ 55 static 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 */ 65 static 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 */ 79 static 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 87 static 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 95 static 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 #ifdef CONFIG_MIGRATION 104 static inline swp_entry_t make_migration_entry(struct page *page, int write) 105 { 106 BUG_ON(!PageLocked(page)); 107 return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ, 108 page_to_pfn(page)); 109 } 110 111 static inline int is_migration_entry(swp_entry_t entry) 112 { 113 return unlikely(swp_type(entry) == SWP_MIGRATION_READ || 114 swp_type(entry) == SWP_MIGRATION_WRITE); 115 } 116 117 static inline int is_write_migration_entry(swp_entry_t entry) 118 { 119 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE); 120 } 121 122 static inline struct page *migration_entry_to_page(swp_entry_t entry) 123 { 124 struct page *p = pfn_to_page(swp_offset(entry)); 125 /* 126 * Any use of migration entries may only occur while the 127 * corresponding page is locked 128 */ 129 BUG_ON(!PageLocked(p)); 130 return p; 131 } 132 133 static inline void make_migration_entry_read(swp_entry_t *entry) 134 { 135 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry)); 136 } 137 138 extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, 139 spinlock_t *ptl); 140 extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, 141 unsigned long address); 142 extern void migration_entry_wait_huge(struct vm_area_struct *vma, 143 struct mm_struct *mm, pte_t *pte); 144 #else 145 146 #define make_migration_entry(page, write) swp_entry(0, 0) 147 static inline int is_migration_entry(swp_entry_t swp) 148 { 149 return 0; 150 } 151 #define migration_entry_to_page(swp) NULL 152 static inline void make_migration_entry_read(swp_entry_t *entryp) { } 153 static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, 154 spinlock_t *ptl) { } 155 static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, 156 unsigned long address) { } 157 static inline void migration_entry_wait_huge(struct vm_area_struct *vma, 158 struct mm_struct *mm, pte_t *pte) { } 159 static inline int is_write_migration_entry(swp_entry_t entry) 160 { 161 return 0; 162 } 163 164 #endif 165 166 #ifdef CONFIG_MEMORY_FAILURE 167 168 extern atomic_long_t num_poisoned_pages __read_mostly; 169 170 /* 171 * Support for hardware poisoned pages 172 */ 173 static inline swp_entry_t make_hwpoison_entry(struct page *page) 174 { 175 BUG_ON(!PageLocked(page)); 176 return swp_entry(SWP_HWPOISON, page_to_pfn(page)); 177 } 178 179 static inline int is_hwpoison_entry(swp_entry_t entry) 180 { 181 return swp_type(entry) == SWP_HWPOISON; 182 } 183 184 static inline bool test_set_page_hwpoison(struct page *page) 185 { 186 return TestSetPageHWPoison(page); 187 } 188 189 static inline void num_poisoned_pages_inc(void) 190 { 191 atomic_long_inc(&num_poisoned_pages); 192 } 193 194 static inline void num_poisoned_pages_dec(void) 195 { 196 atomic_long_dec(&num_poisoned_pages); 197 } 198 199 static inline void num_poisoned_pages_add(long num) 200 { 201 atomic_long_add(num, &num_poisoned_pages); 202 } 203 204 static inline void num_poisoned_pages_sub(long num) 205 { 206 atomic_long_sub(num, &num_poisoned_pages); 207 } 208 #else 209 210 static inline swp_entry_t make_hwpoison_entry(struct page *page) 211 { 212 return swp_entry(0, 0); 213 } 214 215 static inline int is_hwpoison_entry(swp_entry_t swp) 216 { 217 return 0; 218 } 219 220 static inline bool test_set_page_hwpoison(struct page *page) 221 { 222 return false; 223 } 224 225 static inline void num_poisoned_pages_inc(void) 226 { 227 } 228 #endif 229 230 #if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) 231 static inline int non_swap_entry(swp_entry_t entry) 232 { 233 return swp_type(entry) >= MAX_SWAPFILES; 234 } 235 #else 236 static inline int non_swap_entry(swp_entry_t entry) 237 { 238 return 0; 239 } 240 #endif 241 242 #endif /* _LINUX_SWAPOPS_H */ 243