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 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 */
26static 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 */
39static 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 */
48static 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 */
55static inline int is_swap_pte(pte_t pte)
56{
57 return !pte_none(pte) && !pte_present(pte) && !pte_file(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 */
65static inline swp_entry_t pte_to_swp_entry(pte_t pte)
66{
67 swp_entry_t arch_entry;
68
69 BUG_ON(pte_file(pte));
70 if (pte_swp_soft_dirty(pte))
71 pte = pte_swp_clear_soft_dirty(pte);
72 arch_entry = __pte_to_swp_entry(pte);
73 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
74}
75
76/*
77 * Convert the arch-independent representation of a swp_entry_t into the
78 * arch-dependent pte representation.
79 */
80static inline pte_t swp_entry_to_pte(swp_entry_t entry)
81{
82 swp_entry_t arch_entry;
83
84 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
85 BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
86 return __swp_entry_to_pte(arch_entry);
87}
88
89static inline swp_entry_t radix_to_swp_entry(void *arg)
90{
91 swp_entry_t entry;
92
93 entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
94 return entry;
95}
96
97static inline void *swp_to_radix_entry(swp_entry_t entry)
98{
99 unsigned long value;
100
101 value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
102 return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
103}
104
105#ifdef CONFIG_MIGRATION
106static inline swp_entry_t make_migration_entry(struct page *page, int write)
107{
108 BUG_ON(!PageLocked(page));
109 return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
110 page_to_pfn(page));
111}
112
113static inline int is_migration_entry(swp_entry_t entry)
114{
115 return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
116 swp_type(entry) == SWP_MIGRATION_WRITE);
117}
118
119static inline int is_write_migration_entry(swp_entry_t entry)
120{
121 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
122}
123
124static inline struct page *migration_entry_to_page(swp_entry_t entry)
125{
126 struct page *p = pfn_to_page(swp_offset(entry));
127 /*
128 * Any use of migration entries may only occur while the
129 * corresponding page is locked
130 */
131 BUG_ON(!PageLocked(p));
132 return p;
133}
134
135static inline void make_migration_entry_read(swp_entry_t *entry)
136{
137 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
138}
139
140extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
141 unsigned long address);
142extern void migration_entry_wait_huge(struct vm_area_struct *vma,
143 struct mm_struct *mm, pte_t *pte);
144#else
145
146#define make_migration_entry(page, write) swp_entry(0, 0)
147static inline int is_migration_entry(swp_entry_t swp)
148{
149 return 0;
150}
151#define migration_entry_to_page(swp) NULL
152static inline void make_migration_entry_read(swp_entry_t *entryp) { }
153static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
154 unsigned long address) { }
155static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
156 struct mm_struct *mm, pte_t *pte) { }
157static inline int is_write_migration_entry(swp_entry_t entry)
158{
159 return 0;
160}
161
162#endif
163
164#ifdef CONFIG_MEMORY_FAILURE
165/*
166 * Support for hardware poisoned pages
167 */
168static inline swp_entry_t make_hwpoison_entry(struct page *page)
169{
170 BUG_ON(!PageLocked(page));
171 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
172}
173
174static inline int is_hwpoison_entry(swp_entry_t entry)
175{
176 return swp_type(entry) == SWP_HWPOISON;
177}
178#else
179
180static inline swp_entry_t make_hwpoison_entry(struct page *page)
181{
182 return swp_entry(0, 0);
183}
184
185static inline int is_hwpoison_entry(swp_entry_t swp)
186{
187 return 0;
188}
189#endif
190
191#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
192static inline int non_swap_entry(swp_entry_t entry)
193{
194 return swp_type(entry) >= MAX_SWAPFILES;
195}
196#else
197static inline int non_swap_entry(swp_entry_t entry)
198{
199 return 0;
200}
201#endif
202
203#endif /* _LINUX_SWAPOPS_H */