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