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 unsigned long page_ext_size;
40 extern void pgdat_page_ext_init(struct pglist_data *pgdat);
41 
42 #ifdef CONFIG_SPARSEMEM
page_ext_init_flatmem(void)43 static inline void page_ext_init_flatmem(void)
44 {
45 }
46 extern void page_ext_init(void);
page_ext_init_flatmem_late(void)47 static inline void page_ext_init_flatmem_late(void)
48 {
49 }
50 #else
51 extern void page_ext_init_flatmem(void);
52 extern void page_ext_init_flatmem_late(void);
page_ext_init(void)53 static inline void page_ext_init(void)
54 {
55 }
56 #endif
57 
58 struct page_ext *lookup_page_ext(const struct page *page);
59 
page_ext_next(struct page_ext * curr)60 static inline struct page_ext *page_ext_next(struct page_ext *curr)
61 {
62 	void *next = curr;
63 	next += page_ext_size;
64 	return next;
65 }
66 
67 #else /* !CONFIG_PAGE_EXTENSION */
68 struct page_ext;
69 
pgdat_page_ext_init(struct pglist_data * pgdat)70 static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
71 {
72 }
73 
lookup_page_ext(const struct page * page)74 static inline struct page_ext *lookup_page_ext(const struct page *page)
75 {
76 	return NULL;
77 }
78 
page_ext_init(void)79 static inline void page_ext_init(void)
80 {
81 }
82 
page_ext_init_flatmem_late(void)83 static inline void page_ext_init_flatmem_late(void)
84 {
85 }
86 
page_ext_init_flatmem(void)87 static inline void page_ext_init_flatmem(void)
88 {
89 }
90 #endif /* CONFIG_PAGE_EXTENSION */
91 #endif /* __LINUX_PAGE_EXT_H */
92