include/linux/swapops.h

   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(compound_head(page)));
 107
 108         return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
 109                         page_to_pfn(page));
 110 }
 111
 112 static inline int is_migration_entry(swp_entry_t entry)
 113 {
 114         return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
 115                         swp_type(entry) == SWP_MIGRATION_WRITE);
 116 }
 117
 118 static inline int is_write_migration_entry(swp_entry_t entry)
 119 {
 120         return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
 121 }
 122
 123 static inline struct page *migration_entry_to_page(swp_entry_t entry)
 124 {
 125         struct page *p = pfn_to_page(swp_offset(entry));
 126         /*
 127          * Any use of migration entries may only occur while the
 128          * corresponding page is locked
 129          */
 130         BUG_ON(!PageLocked(compound_head(p)));
 131         return p;
 132 }
 133
 134 static inline void make_migration_entry_read(swp_entry_t *entry)
 135 {
 136         *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
 137 }
 138
 139 extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
 140                                         spinlock_t *ptl);
 141 extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
 142                                         unsigned long address);
 143 extern void migration_entry_wait_huge(struct vm_area_struct *vma,
 144                 struct mm_struct *mm, pte_t *pte);
 145 #else
 146
 147 #define make_migration_entry(page, write) swp_entry(0, 0)
 148 static inline int is_migration_entry(swp_entry_t swp)
 149 {
 150         return 0;
 151 }
 152 static inline struct page *migration_entry_to_page(swp_entry_t entry)
 153 {
 154         return NULL;
 155 }
 156
 157 static inline void make_migration_entry_read(swp_entry_t *entryp) { }
 158 static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
 159                                         spinlock_t *ptl) { }
 160 static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
 161                                          unsigned long address) { }
 162 static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
 163                 struct mm_struct *mm, pte_t *pte) { }
 164 static inline int is_write_migration_entry(swp_entry_t entry)
 165 {
 166         return 0;
 167 }
 168
 169 #endif
 170
 171 struct page_vma_mapped_walk;
 172
 173 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
 174 extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
 175                 struct page *page);
 176
 177 extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
 178                 struct page *new);
 179
 180 extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
 181
 182 static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
 183 {
 184         swp_entry_t arch_entry;
 185
 186         if (pmd_swp_soft_dirty(pmd))
 187                 pmd = pmd_swp_clear_soft_dirty(pmd);
 188         arch_entry = __pmd_to_swp_entry(pmd);
 189         return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
 190 }
 191
 192 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
 193 {
 194         swp_entry_t arch_entry;
 195
 196         arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
 197         return __swp_entry_to_pmd(arch_entry);
 198 }
 199
 200 static inline int is_pmd_migration_entry(pmd_t pmd)
 201 {
 202         return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
 203 }
 204 #else
 205 static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
 206                 struct page *page)
 207 {
 208         BUILD_BUG();
 209 }
 210
 211 static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
 212                 struct page *new)
 213 {
 214         BUILD_BUG();
 215 }
 216
 217 static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
 218
 219 static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
 220 {
 221         return swp_entry(0, 0);
 222 }
 223
 224 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
 225 {
 226         return __pmd(0);
 227 }
 228
 229 static inline int is_pmd_migration_entry(pmd_t pmd)
 230 {
 231         return 0;
 232 }
 233 #endif
 234
 235 #ifdef CONFIG_MEMORY_FAILURE
 236
 237 extern atomic_long_t num_poisoned_pages __read_mostly;
 238
 239 /*
 240  * Support for hardware poisoned pages
 241  */
 242 static inline swp_entry_t make_hwpoison_entry(struct page *page)
 243 {
 244         BUG_ON(!PageLocked(page));
 245         return swp_entry(SWP_HWPOISON, page_to_pfn(page));
 246 }
 247
 248 static inline int is_hwpoison_entry(swp_entry_t entry)
 249 {
 250         return swp_type(entry) == SWP_HWPOISON;
 251 }
 252
 253 static inline bool test_set_page_hwpoison(struct page *page)
 254 {
 255         return TestSetPageHWPoison(page);
 256 }
 257
 258 static inline void num_poisoned_pages_inc(void)
 259 {
 260         atomic_long_inc(&num_poisoned_pages);
 261 }
 262
 263 static inline void num_poisoned_pages_dec(void)
 264 {
 265         atomic_long_dec(&num_poisoned_pages);
 266 }
 267
 268 #else
 269
 270 static inline swp_entry_t make_hwpoison_entry(struct page *page)
 271 {
 272         return swp_entry(0, 0);
 273 }
 274
 275 static inline int is_hwpoison_entry(swp_entry_t swp)
 276 {
 277         return 0;
 278 }
 279
 280 static inline bool test_set_page_hwpoison(struct page *page)
 281 {
 282         return false;
 283 }
 284
 285 static inline void num_poisoned_pages_inc(void)
 286 {
 287 }
 288 #endif
 289
 290 #if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
 291 static inline int non_swap_entry(swp_entry_t entry)
 292 {
 293         return swp_type(entry) >= MAX_SWAPFILES;
 294 }
 295 #else
 296 static inline int non_swap_entry(swp_entry_t entry)
 297 {
 298         return 0;
 299 }
 300 #endif
 301
 302 #endif /* _LINUX_SWAPOPS_H */