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
32#ifdef CONFIG_PAGE_EXTENSION
33
34/*
35 * The page_ext_flags users must set need_shared_flags to true.
36 */
37enum page_ext_flags {
38 PAGE_EXT_OWNER,
39 PAGE_EXT_OWNER_ALLOCATED,
40#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
41 PAGE_EXT_YOUNG,
42 PAGE_EXT_IDLE,
43#endif
44};
45
46/*
47 * Page Extension can be considered as an extended mem_map.
48 * A page_ext page is associated with every page descriptor. The
49 * page_ext helps us add more information about the page.
50 * All page_ext are allocated at boot or memory hotplug event,
51 * then the page_ext for pfn always exists.
52 */
53struct page_ext {
54 unsigned long flags;
55};
56
57extern bool early_page_ext;
58extern unsigned long page_ext_size;
59extern void pgdat_page_ext_init(struct pglist_data *pgdat);
60
61static inline bool early_page_ext_enabled(void)
62{
63 return early_page_ext;
64}
65
66#ifdef CONFIG_SPARSEMEM
67static inline void page_ext_init_flatmem(void)
68{
69}
70extern void page_ext_init(void);
71static inline void page_ext_init_flatmem_late(void)
72{
73}
74#else
75extern void page_ext_init_flatmem(void);
76extern void page_ext_init_flatmem_late(void);
77static inline void page_ext_init(void)
78{
79}
80#endif
81
82extern struct page_ext *page_ext_get(struct page *page);
83extern void page_ext_put(struct page_ext *page_ext);
84
85static inline struct page_ext *page_ext_next(struct page_ext *curr)
86{
87 void *next = curr;
88 next += page_ext_size;
89 return next;
90}
91
92#else /* !CONFIG_PAGE_EXTENSION */
93struct page_ext;
94
95static inline bool early_page_ext_enabled(void)
96{
97 return false;
98}
99
100static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
101{
102}
103
104static inline void page_ext_init(void)
105{
106}
107
108static inline void page_ext_init_flatmem_late(void)
109{
110}
111
112static inline void page_ext_init_flatmem(void)
113{
114}
115
116static inline struct page_ext *page_ext_get(struct page *page)
117{
118 return NULL;
119}
120
121static inline void page_ext_put(struct page_ext *page_ext)
122{
123}
124#endif /* CONFIG_PAGE_EXTENSION */
125#endif /* __LINUX_PAGE_EXT_H */