1 #ifndef _LINUX_SWAPOPS_H
2 #define _LINUX_SWAPOPS_H
3
4 #include <linux/radix-tree.h>
5
6 /*
7 * swapcache pages are stored in the swapper_space radix tree. We want to
8 * get good packing density in that tree, so the index should be dense in
9 * the low-order bits.
10 *
11 * We arrange the `type' and `offset' fields so that `type' is at the five
12 * high-order bits of the swp_entry_t and `offset' is right-aligned in the
13 * remaining bits.
14 *
15 * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
16 */
17 #define SWP_TYPE_SHIFT(e) (sizeof(e.val) * 8 - MAX_SWAPFILES_SHIFT)
18 #define SWP_OFFSET_MASK(e) ((1UL << SWP_TYPE_SHIFT(e)) - 1)
19
20 /*
21 * Store a type+offset into a swp_entry_t in an arch-independent format
22 */
swp_entry(unsigned long type,pgoff_t offset)23 static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
24 {
25 swp_entry_t ret;
26
27 ret.val = (type << SWP_TYPE_SHIFT(ret)) |
28 (offset & SWP_OFFSET_MASK(ret));
29 return ret;
30 }
31
32 /*
33 * Extract the `type' field from a swp_entry_t. The swp_entry_t is in
34 * arch-independent format
35 */
swp_type(swp_entry_t entry)36 static inline unsigned swp_type(swp_entry_t entry)
37 {
38 return (entry.val >> SWP_TYPE_SHIFT(entry));
39 }
40
41 /*
42 * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
43 * arch-independent format
44 */
swp_offset(swp_entry_t entry)45 static inline pgoff_t swp_offset(swp_entry_t entry)
46 {
47 return entry.val & SWP_OFFSET_MASK(entry);
48 }
49
50 #ifdef CONFIG_MMU
51 /* check whether a pte points to a swap entry */
is_swap_pte(pte_t pte)52 static inline int is_swap_pte(pte_t pte)
53 {
54 return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
55 }
56 #endif
57
58 /*
59 * Convert the arch-dependent pte representation of a swp_entry_t into an
60 * arch-independent swp_entry_t.
61 */
pte_to_swp_entry(pte_t pte)62 static inline swp_entry_t pte_to_swp_entry(pte_t pte)
63 {
64 swp_entry_t arch_entry;
65
66 BUG_ON(pte_file(pte));
67 arch_entry = __pte_to_swp_entry(pte);
68 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
69 }
70
71 /*
72 * Convert the arch-independent representation of a swp_entry_t into the
73 * arch-dependent pte representation.
74 */
swp_entry_to_pte(swp_entry_t entry)75 static inline pte_t swp_entry_to_pte(swp_entry_t entry)
76 {
77 swp_entry_t arch_entry;
78
79 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
80 BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
81 return __swp_entry_to_pte(arch_entry);
82 }
83
radix_to_swp_entry(void * arg)84 static inline swp_entry_t radix_to_swp_entry(void *arg)
85 {
86 swp_entry_t entry;
87
88 entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
89 return entry;
90 }
91
swp_to_radix_entry(swp_entry_t entry)92 static inline void *swp_to_radix_entry(swp_entry_t entry)
93 {
94 unsigned long value;
95
96 value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
97 return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
98 }
99
100 #ifdef CONFIG_MIGRATION
make_migration_entry(struct page * page,int write)101 static inline swp_entry_t make_migration_entry(struct page *page, int write)
102 {
103 BUG_ON(!PageLocked(page));
104 return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
105 page_to_pfn(page));
106 }
107
is_migration_entry(swp_entry_t entry)108 static inline int is_migration_entry(swp_entry_t entry)
109 {
110 return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
111 swp_type(entry) == SWP_MIGRATION_WRITE);
112 }
113
is_write_migration_entry(swp_entry_t entry)114 static inline int is_write_migration_entry(swp_entry_t entry)
115 {
116 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
117 }
118
migration_entry_to_page(swp_entry_t entry)119 static inline struct page *migration_entry_to_page(swp_entry_t entry)
120 {
121 struct page *p = pfn_to_page(swp_offset(entry));
122 /*
123 * Any use of migration entries may only occur while the
124 * corresponding page is locked
125 */
126 BUG_ON(!PageLocked(p));
127 return p;
128 }
129
make_migration_entry_read(swp_entry_t * entry)130 static inline void make_migration_entry_read(swp_entry_t *entry)
131 {
132 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
133 }
134
135 extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
136 unsigned long address);
137 #else
138
139 #define make_migration_entry(page, write) swp_entry(0, 0)
is_migration_entry(swp_entry_t swp)140 static inline int is_migration_entry(swp_entry_t swp)
141 {
142 return 0;
143 }
144 #define migration_entry_to_page(swp) NULL
make_migration_entry_read(swp_entry_t * entryp)145 static inline void make_migration_entry_read(swp_entry_t *entryp) { }
migration_entry_wait(struct mm_struct * mm,pmd_t * pmd,unsigned long address)146 static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
147 unsigned long address) { }
is_write_migration_entry(swp_entry_t entry)148 static inline int is_write_migration_entry(swp_entry_t entry)
149 {
150 return 0;
151 }
152
153 #endif
154
155 #ifdef CONFIG_MEMORY_FAILURE
156 /*
157 * Support for hardware poisoned pages
158 */
make_hwpoison_entry(struct page * page)159 static inline swp_entry_t make_hwpoison_entry(struct page *page)
160 {
161 BUG_ON(!PageLocked(page));
162 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
163 }
164
is_hwpoison_entry(swp_entry_t entry)165 static inline int is_hwpoison_entry(swp_entry_t entry)
166 {
167 return swp_type(entry) == SWP_HWPOISON;
168 }
169 #else
170
make_hwpoison_entry(struct page * page)171 static inline swp_entry_t make_hwpoison_entry(struct page *page)
172 {
173 return swp_entry(0, 0);
174 }
175
is_hwpoison_entry(swp_entry_t swp)176 static inline int is_hwpoison_entry(swp_entry_t swp)
177 {
178 return 0;
179 }
180 #endif
181
182 #if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
non_swap_entry(swp_entry_t entry)183 static inline int non_swap_entry(swp_entry_t entry)
184 {
185 return swp_type(entry) >= MAX_SWAPFILES;
186 }
187 #else
non_swap_entry(swp_entry_t entry)188 static inline int non_swap_entry(swp_entry_t entry)
189 {
190 return 0;
191 }
192 #endif
193
194 #endif /* _LINUX_SWAPOPS_H */
195