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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
8struct pglist_data;
9
10#ifdef CONFIG_PAGE_EXTENSION
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/*
33 * The page_ext_flags users must set need_shared_flags to true.
34 */
35enum page_ext_flags {
36 PAGE_EXT_OWNER,
37 PAGE_EXT_OWNER_ALLOCATED,
38#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
39 PAGE_EXT_YOUNG,
40 PAGE_EXT_IDLE,
41#endif
42};
43
44/*
45 * Page Extension can be considered as an extended mem_map.
46 * A page_ext page is associated with every page descriptor. The
47 * page_ext helps us add more information about the page.
48 * All page_ext are allocated at boot or memory hotplug event,
49 * then the page_ext for pfn always exists.
50 */
51struct page_ext {
52 unsigned long flags;
53};
54
55extern bool early_page_ext;
56extern unsigned long page_ext_size;
57extern void pgdat_page_ext_init(struct pglist_data *pgdat);
58
59static inline bool early_page_ext_enabled(void)
60{
61 return early_page_ext;
62}
63
64#ifdef CONFIG_SPARSEMEM
65static inline void page_ext_init_flatmem(void)
66{
67}
68extern void page_ext_init(void);
69static inline void page_ext_init_flatmem_late(void)
70{
71}
72#else
73extern void page_ext_init_flatmem(void);
74extern void page_ext_init_flatmem_late(void);
75static inline void page_ext_init(void)
76{
77}
78#endif
79
80extern struct page_ext *page_ext_get(const struct page *page);
81extern void page_ext_put(struct page_ext *page_ext);
82
83static inline void *page_ext_data(struct page_ext *page_ext,
84 struct page_ext_operations *ops)
85{
86 return (void *)(page_ext) + ops->offset;
87}
88
89static inline struct page_ext *page_ext_next(struct page_ext *curr)
90{
91 void *next = curr;
92 next += page_ext_size;
93 return next;
94}
95
96#else /* !CONFIG_PAGE_EXTENSION */
97struct page_ext;
98
99static inline bool early_page_ext_enabled(void)
100{
101 return false;
102}
103
104static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
105{
106}
107
108static inline void page_ext_init(void)
109{
110}
111
112static inline void page_ext_init_flatmem_late(void)
113{
114}
115
116static inline void page_ext_init_flatmem(void)
117{
118}
119
120static inline struct page_ext *page_ext_get(const struct page *page)
121{
122 return NULL;
123}
124
125static inline void page_ext_put(struct page_ext *page_ext)
126{
127}
128#endif /* CONFIG_PAGE_EXTENSION */
129#endif /* __LINUX_PAGE_EXT_H */