Linux kernel mirror (for testing)
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linux
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 */
23static 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 */
36static 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 */
45static 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 */
52static 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 */
62static 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 */
75static 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
84static 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
92static 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
101static 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
108static 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
114static inline int is_write_migration_entry(swp_entry_t entry)
115{
116 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
117}
118
119static 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
130static inline void make_migration_entry_read(swp_entry_t *entry)
131{
132 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
133}
134
135extern 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)
140static inline int is_migration_entry(swp_entry_t swp)
141{
142 return 0;
143}
144#define migration_entry_to_page(swp) NULL
145static inline void make_migration_entry_read(swp_entry_t *entryp) { }
146static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
147 unsigned long address) { }
148static 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 */
159static 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
165static inline int is_hwpoison_entry(swp_entry_t entry)
166{
167 return swp_type(entry) == SWP_HWPOISON;
168}
169#else
170
171static inline swp_entry_t make_hwpoison_entry(struct page *page)
172{
173 return swp_entry(0, 0);
174}
175
176static 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)
183static inline int non_swap_entry(swp_entry_t entry)
184{
185 return swp_type(entry) >= MAX_SWAPFILES;
186}
187#else
188static inline int non_swap_entry(swp_entry_t entry)
189{
190 return 0;
191}
192#endif
193
194#endif /* _LINUX_SWAPOPS_H */