Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
7 * high-order bits of the swp_entry_t and `offset' is right-aligned in the
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 */
18static 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 */
31static 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 */
40static inline pgoff_t swp_offset(swp_entry_t entry)
41{
42 return entry.val & SWP_OFFSET_MASK(entry);
43}
44
45#ifdef CONFIG_MMU
46/* check whether a pte points to a swap entry */
47static inline int is_swap_pte(pte_t pte)
48{
49 return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
50}
51#endif
52
53/*
54 * Convert the arch-dependent pte representation of a swp_entry_t into an
55 * arch-independent swp_entry_t.
56 */
57static 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 */
70static 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}
78
79#ifdef CONFIG_MIGRATION
80static 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
87static 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
93static inline int is_write_migration_entry(swp_entry_t entry)
94{
95 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
96}
97
98static 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
109static inline void make_migration_entry_read(swp_entry_t *entry)
110{
111 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
112}
113
114extern 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)
119static inline int is_migration_entry(swp_entry_t swp)
120{
121 return 0;
122}
123#define migration_entry_to_page(swp) NULL
124static inline void make_migration_entry_read(swp_entry_t *entryp) { }
125static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
126 unsigned long address) { }
127static inline int is_write_migration_entry(swp_entry_t entry)
128{
129 return 0;
130}
131
132#endif
133
134#ifdef CONFIG_MEMORY_FAILURE
135/*
136 * Support for hardware poisoned pages
137 */
138static inline swp_entry_t make_hwpoison_entry(struct page *page)
139{
140 BUG_ON(!PageLocked(page));
141 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
142}
143
144static inline int is_hwpoison_entry(swp_entry_t entry)
145{
146 return swp_type(entry) == SWP_HWPOISON;
147}
148#else
149
150static inline swp_entry_t make_hwpoison_entry(struct page *page)
151{
152 return swp_entry(0, 0);
153}
154
155static inline int is_hwpoison_entry(swp_entry_t swp)
156{
157 return 0;
158}
159#endif
160
161#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
162static inline int non_swap_entry(swp_entry_t entry)
163{
164 return swp_type(entry) >= MAX_SWAPFILES;
165}
166#else
167static inline int non_swap_entry(swp_entry_t entry)
168{
169 return 0;
170}
171#endif