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_DEBUG_GUARD,
21 	PAGE_EXT_OWNER,
22 #if defined(CONFIG_IDLE_PAGE_TRACKING) && !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 void pgdat_page_ext_init(struct pglist_data *pgdat);
40 
41 #ifdef CONFIG_SPARSEMEM
page_ext_init_flatmem(void)42 static inline void page_ext_init_flatmem(void)
43 {
44 }
45 extern void page_ext_init(void);
46 #else
47 extern void page_ext_init_flatmem(void);
page_ext_init(void)48 static inline void page_ext_init(void)
49 {
50 }
51 #endif
52 
53 struct page_ext *lookup_page_ext(const struct page *page);
54 
55 #else /* !CONFIG_PAGE_EXTENSION */
56 struct page_ext;
57 
pgdat_page_ext_init(struct pglist_data * pgdat)58 static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
59 {
60 }
61 
lookup_page_ext(const struct page * page)62 static inline struct page_ext *lookup_page_ext(const struct page *page)
63 {
64 	return NULL;
65 }
66 
page_ext_init(void)67 static inline void page_ext_init(void)
68 {
69 }
70 
page_ext_init_flatmem(void)71 static inline void page_ext_init_flatmem(void)
72 {
73 }
74 #endif /* CONFIG_PAGE_EXTENSION */
75 #endif /* __LINUX_PAGE_EXT_H */
76