Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_PAGE_EXT_H
3#define __LINUX_PAGE_EXT_H
4
5#include <linux/types.h>
6#include <linux/stacktrace.h>
7#include <linux/stackdepot.h>
8
9struct pglist_data;
10
11/**
12 * struct page_ext_operations - per page_ext client operations
13 * @offset: Offset to the client's data within page_ext. Offset is returned to
14 * the client by page_ext_init.
15 * @size: The size of the client data within page_ext.
16 * @need: Function that returns true if client requires page_ext.
17 * @init: (optional) Called to initialize client once page_exts are allocated.
18 * @need_shared_flags: True when client is using shared page_ext->flags
19 * field.
20 *
21 * Each Page Extension client must define page_ext_operations in
22 * page_ext_ops array.
23 */
24struct page_ext_operations {
25 size_t offset;
26 size_t size;
27 bool (*need)(void);
28 void (*init)(void);
29 bool need_shared_flags;
30};
31
32extern bool deferred_struct_pages;
33
34#ifdef CONFIG_PAGE_EXTENSION
35
36/*
37 * The page_ext_flags users must set need_shared_flags to true.
38 */
39enum page_ext_flags {
40 PAGE_EXT_OWNER,
41 PAGE_EXT_OWNER_ALLOCATED,
42#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
43 PAGE_EXT_YOUNG,
44 PAGE_EXT_IDLE,
45#endif
46};
47
48/*
49 * Page Extension can be considered as an extended mem_map.
50 * A page_ext page is associated with every page descriptor. The
51 * page_ext helps us add more information about the page.
52 * All page_ext are allocated at boot or memory hotplug event,
53 * then the page_ext for pfn always exists.
54 */
55struct page_ext {
56 unsigned long flags;
57};
58
59extern bool early_page_ext;
60extern unsigned long page_ext_size;
61extern void pgdat_page_ext_init(struct pglist_data *pgdat);
62
63static inline bool early_page_ext_enabled(void)
64{
65 return early_page_ext;
66}
67
68#ifdef CONFIG_SPARSEMEM
69static inline void page_ext_init_flatmem(void)
70{
71}
72extern void page_ext_init(void);
73static inline void page_ext_init_flatmem_late(void)
74{
75}
76#else
77extern void page_ext_init_flatmem(void);
78extern void page_ext_init_flatmem_late(void);
79static inline void page_ext_init(void)
80{
81}
82#endif
83
84extern struct page_ext *page_ext_get(struct page *page);
85extern void page_ext_put(struct page_ext *page_ext);
86
87static inline struct page_ext *page_ext_next(struct page_ext *curr)
88{
89 void *next = curr;
90 next += page_ext_size;
91 return next;
92}
93
94#else /* !CONFIG_PAGE_EXTENSION */
95struct page_ext;
96
97static inline bool early_page_ext_enabled(void)
98{
99 return false;
100}
101
102static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
103{
104}
105
106static inline void page_ext_init(void)
107{
108}
109
110static inline void page_ext_init_flatmem_late(void)
111{
112}
113
114static inline void page_ext_init_flatmem(void)
115{
116}
117
118static inline struct page_ext *page_ext_get(struct page *page)
119{
120 return NULL;
121}
122
123static inline void page_ext_put(struct page_ext *page_ext)
124{
125}
126#endif /* CONFIG_PAGE_EXTENSION */
127#endif /* __LINUX_PAGE_EXT_H */