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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 
9 struct pglist_data;
10 struct page_ext_operations {
11 	size_t offset;
12 	size_t size;
13 	bool (*need)(void);
14 	void (*init)(void);
15 };
16 
17 #ifdef CONFIG_PAGE_EXTENSION
18 
19 enum page_ext_flags {
20 	PAGE_EXT_OWNER,
21 	PAGE_EXT_OWNER_ALLOCATED,
22 #if defined(CONFIG_PAGE_PINNER)
23 	/* page migration failed */
24 	PAGE_EXT_PINNER_MIGRATION_FAILED,
25 #endif
26 #if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
27 	PAGE_EXT_YOUNG,
28 	PAGE_EXT_IDLE,
29 #endif
30 };
31 
32 /*
33  * Page Extension can be considered as an extended mem_map.
34  * A page_ext page is associated with every page descriptor. The
35  * page_ext helps us add more information about the page.
36  * All page_ext are allocated at boot or memory hotplug event,
37  * then the page_ext for pfn always exists.
38  */
39 struct page_ext {
40 	unsigned long flags;
41 };
42 
43 extern bool early_page_ext;
44 extern unsigned long page_ext_size;
45 extern void pgdat_page_ext_init(struct pglist_data *pgdat);
46 
early_page_ext_enabled(void)47 static inline bool early_page_ext_enabled(void)
48 {
49 	return early_page_ext;
50 }
51 
52 #ifdef CONFIG_SPARSEMEM
page_ext_init_flatmem(void)53 static inline void page_ext_init_flatmem(void)
54 {
55 }
56 extern void page_ext_init(void);
page_ext_init_flatmem_late(void)57 static inline void page_ext_init_flatmem_late(void)
58 {
59 }
60 #else
61 extern void page_ext_init_flatmem(void);
62 extern void page_ext_init_flatmem_late(void);
page_ext_init(void)63 static inline void page_ext_init(void)
64 {
65 }
66 #endif
67 
68 extern struct page_ext *page_ext_get(struct page *page);
69 extern void page_ext_put(struct page_ext *page_ext);
70 
page_ext_next(struct page_ext * curr)71 static inline struct page_ext *page_ext_next(struct page_ext *curr)
72 {
73 	void *next = curr;
74 	next += page_ext_size;
75 	return next;
76 }
77 
78 #else /* !CONFIG_PAGE_EXTENSION */
79 struct page_ext;
80 
early_page_ext_enabled(void)81 static inline bool early_page_ext_enabled(void)
82 {
83 	return false;
84 }
85 
pgdat_page_ext_init(struct pglist_data * pgdat)86 static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
87 {
88 }
89 
page_ext_init(void)90 static inline void page_ext_init(void)
91 {
92 }
93 
page_ext_init_flatmem_late(void)94 static inline void page_ext_init_flatmem_late(void)
95 {
96 }
97 
page_ext_init_flatmem(void)98 static inline void page_ext_init_flatmem(void)
99 {
100 }
101 
page_ext_get(struct page * page)102 static inline struct page_ext *page_ext_get(struct page *page)
103 {
104 	return NULL;
105 }
106 
page_ext_put(struct page_ext * page_ext)107 static inline void page_ext_put(struct page_ext *page_ext)
108 {
109 }
110 #endif /* CONFIG_PAGE_EXTENSION */
111 #endif /* __LINUX_PAGE_EXT_H */
112