xref: /openbmc/linux/include/linux/page_ext.h (revision 67311a36) 
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 
11 #ifdef CONFIG_PAGE_EXTENSION
12 /**
13  * struct page_ext_operations - per page_ext client operations
14  * @offset: Offset to the client's data within page_ext. Offset is returned to
15  *          the client by page_ext_init.
16  * @size: The size of the client data within page_ext.
17  * @need: Function that returns true if client requires page_ext.
18  * @init: (optional) Called to initialize client once page_exts are allocated.
19  * @need_shared_flags: True when client is using shared page_ext->flags
20  *                     field.
21  *
22  * Each Page Extension client must define page_ext_operations in
23  * page_ext_ops array.
24  */
25 struct page_ext_operations {
26 	size_t offset;
27 	size_t size;
28 	bool (*need)(void);
29 	void (*init)(void);
30 	bool need_shared_flags;
31 };
32 
33 /*
34  * The page_ext_flags users must set need_shared_flags to true.
35  */
36 enum page_ext_flags {
37 	PAGE_EXT_OWNER,
38 	PAGE_EXT_OWNER_ALLOCATED,
39 #if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
40 	PAGE_EXT_YOUNG,
41 	PAGE_EXT_IDLE,
42 #endif
43 };
44 
45 /*
46  * Page Extension can be considered as an extended mem_map.
47  * A page_ext page is associated with every page descriptor. The
48  * page_ext helps us add more information about the page.
49  * All page_ext are allocated at boot or memory hotplug event,
50  * then the page_ext for pfn always exists.
51  */
52 struct page_ext {
53 	unsigned long flags;
54 };
55 
56 extern bool early_page_ext;
57 extern unsigned long page_ext_size;
58 extern void pgdat_page_ext_init(struct pglist_data *pgdat);
59 
early_page_ext_enabled(void)60 static inline bool early_page_ext_enabled(void)
61 {
62 	return early_page_ext;
63 }
64 
65 #ifdef CONFIG_SPARSEMEM
page_ext_init_flatmem(void)66 static inline void page_ext_init_flatmem(void)
67 {
68 }
69 extern void page_ext_init(void);
page_ext_init_flatmem_late(void)70 static inline void page_ext_init_flatmem_late(void)
71 {
72 }
73 #else
74 extern void page_ext_init_flatmem(void);
75 extern void page_ext_init_flatmem_late(void);
page_ext_init(void)76 static inline void page_ext_init(void)
77 {
78 }
79 #endif
80 
81 extern struct page_ext *page_ext_get(struct page *page);
82 extern void page_ext_put(struct page_ext *page_ext);
83 
page_ext_data(struct page_ext * page_ext,struct page_ext_operations * ops)84 static inline void *page_ext_data(struct page_ext *page_ext,
85 				  struct page_ext_operations *ops)
86 {
87 	return (void *)(page_ext) + ops->offset;
88 }
89 
page_ext_next(struct page_ext * curr)90 static inline struct page_ext *page_ext_next(struct page_ext *curr)
91 {
92 	void *next = curr;
93 	next += page_ext_size;
94 	return next;
95 }
96 
97 #else /* !CONFIG_PAGE_EXTENSION */
98 struct page_ext;
99 
early_page_ext_enabled(void)100 static inline bool early_page_ext_enabled(void)
101 {
102 	return false;
103 }
104 
pgdat_page_ext_init(struct pglist_data * pgdat)105 static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
106 {
107 }
108 
page_ext_init(void)109 static inline void page_ext_init(void)
110 {
111 }
112 
page_ext_init_flatmem_late(void)113 static inline void page_ext_init_flatmem_late(void)
114 {
115 }
116 
page_ext_init_flatmem(void)117 static inline void page_ext_init_flatmem(void)
118 {
119 }
120 
page_ext_get(struct page * page)121 static inline struct page_ext *page_ext_get(struct page *page)
122 {
123 	return NULL;
124 }
125 
page_ext_put(struct page_ext * page_ext)126 static inline void page_ext_put(struct page_ext *page_ext)
127 {
128 }
129 #endif /* CONFIG_PAGE_EXTENSION */
130 #endif /* __LINUX_PAGE_EXT_H */
131