Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * swapcache pages are stored in the swapper_space radix tree. We want to | |
3 | * get good packing density in that tree, so the index should be dense in | |
4 | * the low-order bits. | |
5 | * | |
6 | * We arrange the `type' and `offset' fields so that `type' is at the five | |
e83a9596 | 7 | * high-order bits of the swp_entry_t and `offset' is right-aligned in the |
1da177e4 LT |
8 | * remaining bits. |
9 | * | |
10 | * swp_entry_t's are *never* stored anywhere in their arch-dependent format. | |
11 | */ | |
12 | #define SWP_TYPE_SHIFT(e) (sizeof(e.val) * 8 - MAX_SWAPFILES_SHIFT) | |
13 | #define SWP_OFFSET_MASK(e) ((1UL << SWP_TYPE_SHIFT(e)) - 1) | |
14 | ||
15 | /* | |
16 | * Store a type+offset into a swp_entry_t in an arch-independent format | |
17 | */ | |
18 | static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset) | |
19 | { | |
20 | swp_entry_t ret; | |
21 | ||
22 | ret.val = (type << SWP_TYPE_SHIFT(ret)) | | |
23 | (offset & SWP_OFFSET_MASK(ret)); | |
24 | return ret; | |
25 | } | |
26 | ||
27 | /* | |
28 | * Extract the `type' field from a swp_entry_t. The swp_entry_t is in | |
29 | * arch-independent format | |
30 | */ | |
31 | static inline unsigned swp_type(swp_entry_t entry) | |
32 | { | |
33 | return (entry.val >> SWP_TYPE_SHIFT(entry)); | |
34 | } | |
35 | ||
36 | /* | |
37 | * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in | |
38 | * arch-independent format | |
39 | */ | |
40 | static inline pgoff_t swp_offset(swp_entry_t entry) | |
41 | { | |
42 | return entry.val & SWP_OFFSET_MASK(entry); | |
43 | } | |
44 | ||
880cdf3a | 45 | #ifdef CONFIG_MMU |
698dd4ba MM |
46 | /* check whether a pte points to a swap entry */ |
47 | static inline int is_swap_pte(pte_t pte) | |
48 | { | |
49 | return !pte_none(pte) && !pte_present(pte) && !pte_file(pte); | |
50 | } | |
880cdf3a | 51 | #endif |
698dd4ba | 52 | |
1da177e4 LT |
53 | /* |
54 | * Convert the arch-dependent pte representation of a swp_entry_t into an | |
55 | * arch-independent swp_entry_t. | |
56 | */ | |
57 | static inline swp_entry_t pte_to_swp_entry(pte_t pte) | |
58 | { | |
59 | swp_entry_t arch_entry; | |
60 | ||
61 | BUG_ON(pte_file(pte)); | |
62 | arch_entry = __pte_to_swp_entry(pte); | |
63 | return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); | |
64 | } | |
65 | ||
66 | /* | |
67 | * Convert the arch-independent representation of a swp_entry_t into the | |
68 | * arch-dependent pte representation. | |
69 | */ | |
70 | static inline pte_t swp_entry_to_pte(swp_entry_t entry) | |
71 | { | |
72 | swp_entry_t arch_entry; | |
73 | ||
74 | arch_entry = __swp_entry(swp_type(entry), swp_offset(entry)); | |
75 | BUG_ON(pte_file(__swp_entry_to_pte(arch_entry))); | |
76 | return __swp_entry_to_pte(arch_entry); | |
77 | } | |
0697212a CL |
78 | |
79 | #ifdef CONFIG_MIGRATION | |
80 | static inline swp_entry_t make_migration_entry(struct page *page, int write) | |
81 | { | |
82 | BUG_ON(!PageLocked(page)); | |
83 | return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ, | |
84 | page_to_pfn(page)); | |
85 | } | |
86 | ||
87 | static inline int is_migration_entry(swp_entry_t entry) | |
88 | { | |
89 | return unlikely(swp_type(entry) == SWP_MIGRATION_READ || | |
90 | swp_type(entry) == SWP_MIGRATION_WRITE); | |
91 | } | |
92 | ||
93 | static inline int is_write_migration_entry(swp_entry_t entry) | |
94 | { | |
95 | return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE); | |
96 | } | |
97 | ||
98 | static inline struct page *migration_entry_to_page(swp_entry_t entry) | |
99 | { | |
100 | struct page *p = pfn_to_page(swp_offset(entry)); | |
101 | /* | |
102 | * Any use of migration entries may only occur while the | |
103 | * corresponding page is locked | |
104 | */ | |
105 | BUG_ON(!PageLocked(p)); | |
106 | return p; | |
107 | } | |
108 | ||
109 | static inline void make_migration_entry_read(swp_entry_t *entry) | |
110 | { | |
111 | *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry)); | |
112 | } | |
113 | ||
114 | extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
115 | unsigned long address); | |
116 | #else | |
117 | ||
118 | #define make_migration_entry(page, write) swp_entry(0, 0) | |
5ec553a9 AM |
119 | static inline int is_migration_entry(swp_entry_t swp) |
120 | { | |
121 | return 0; | |
122 | } | |
0697212a CL |
123 | #define migration_entry_to_page(swp) NULL |
124 | static inline void make_migration_entry_read(swp_entry_t *entryp) { } | |
125 | static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, | |
126 | unsigned long address) { } | |
127 | static inline int is_write_migration_entry(swp_entry_t entry) | |
128 | { | |
129 | return 0; | |
130 | } | |
131 | ||
132 | #endif | |
133 |