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) && !pte_file(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 BUG_ON(pte_file(pte)); 70 if (pte_swp_soft_dirty(pte)) 71 pte = pte_swp_clear_soft_dirty(pte); 72 arch_entry = __pte_to_swp_entry(pte); 73 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); 74 } 75 76 /* 77 * Convert the arch-independent representation of a swp_entry_t into the 78 * arch-dependent pte representation. 79 */ 80 static inline pte_t swp_entry_to_pte(swp_entry_t entry) 81 { 82 swp_entry_t arch_entry; 83 84 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry)); 85 BUG_ON(pte_file(__swp_entry_to_pte(arch_entry))); 86 return __swp_entry_to_pte(arch_entry); 87 } 88 89 static inline swp_entry_t radix_to_swp_entry(void *arg) 90 { 91 swp_entry_t entry; 92 93 entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT; 94 return entry; 95 } 96 97 static inline void *swp_to_radix_entry(swp_entry_t entry) 98 { 99 unsigned long value; 100 101 value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT; 102 return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY); 103 } 104 105 #ifdef CONFIG_MIGRATION 106 static inline swp_entry_t make_migration_entry(struct page *page, int write) 107 { 108 BUG_ON(!PageLocked(page)); 109 return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ, 110 page_to_pfn(page)); 111 } 112 113 static inline int is_migration_entry(swp_entry_t entry) 114 { 115 return unlikely(swp_type(entry) == SWP_MIGRATION_READ || 116 swp_type(entry) == SWP_MIGRATION_WRITE); 117 } 118 119 static inline int is_write_migration_entry(swp_entry_t entry) 120 { 121 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE); 122 } 123 124 static inline struct page *migration_entry_to_page(swp_entry_t entry) 125 { 126 struct page *p = pfn_to_page(swp_offset(entry)); 127 /* 128 * Any use of migration entries may only occur while the 129 * corresponding page is locked 130 */ 131 BUG_ON(!PageLocked(p)); 132 return p; 133 } 134 135 static inline void make_migration_entry_read(swp_entry_t *entry) 136 { 137 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry)); 138 } 139 140 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, pmd_t *pmd, 154 unsigned long address) { } 155 static inline void migration_entry_wait_huge(struct vm_area_struct *vma, 156 struct mm_struct *mm, pte_t *pte) { } 157 static inline int is_write_migration_entry(swp_entry_t entry) 158 { 159 return 0; 160 } 161 162 #endif 163 164 #ifdef CONFIG_MEMORY_FAILURE 165 /* 166 * Support for hardware poisoned pages 167 */ 168 static inline swp_entry_t make_hwpoison_entry(struct page *page) 169 { 170 BUG_ON(!PageLocked(page)); 171 return swp_entry(SWP_HWPOISON, page_to_pfn(page)); 172 } 173 174 static inline int is_hwpoison_entry(swp_entry_t entry) 175 { 176 return swp_type(entry) == SWP_HWPOISON; 177 } 178 #else 179 180 static inline swp_entry_t make_hwpoison_entry(struct page *page) 181 { 182 return swp_entry(0, 0); 183 } 184 185 static inline int is_hwpoison_entry(swp_entry_t swp) 186 { 187 return 0; 188 } 189 #endif 190 191 #if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) 192 static inline int non_swap_entry(swp_entry_t entry) 193 { 194 return swp_type(entry) >= MAX_SWAPFILES; 195 } 196 #else 197 static inline int non_swap_entry(swp_entry_t entry) 198 { 199 return 0; 200 } 201 #endif 202 203 #endif /* _LINUX_SWAPOPS_H */ 204