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