1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SLAB_DEF_H
3 #define _LINUX_SLAB_DEF_H
4
5 #include <linux/reciprocal_div.h>
6
7 /*
8 * Definitions unique to the original Linux SLAB allocator.
9 */
10
11 struct kmem_cache {
12 struct array_cache __percpu *cpu_cache;
13
14 /* 1) Cache tunables. Protected by slab_mutex */
15 unsigned int batchcount;
16 unsigned int limit;
17 unsigned int shared;
18
19 unsigned int size;
20 struct reciprocal_value reciprocal_buffer_size;
21 /* 2) touched by every alloc & free from the backend */
22
23 slab_flags_t flags; /* constant flags */
24 unsigned int num; /* # of objs per slab */
25
26 /* 3) cache_grow/shrink */
27 /* order of pgs per slab (2^n) */
28 unsigned int gfporder;
29
30 /* force GFP flags, e.g. GFP_DMA */
31 gfp_t allocflags;
32
33 size_t colour; /* cache colouring range */
34 unsigned int colour_off; /* colour offset */
35 struct kmem_cache *freelist_cache;
36 unsigned int freelist_size;
37
38 /* constructor func */
39 void (*ctor)(void *obj);
40
41 /* 4) cache creation/removal */
42 const char *name;
43 struct list_head list;
44 int refcount;
45 int object_size;
46 int align;
47
48 /* 5) statistics */
49 #ifdef CONFIG_DEBUG_SLAB
50 unsigned long num_active;
51 unsigned long num_allocations;
52 unsigned long high_mark;
53 unsigned long grown;
54 unsigned long reaped;
55 unsigned long errors;
56 unsigned long max_freeable;
57 unsigned long node_allocs;
58 unsigned long node_frees;
59 unsigned long node_overflow;
60 atomic_t allochit;
61 atomic_t allocmiss;
62 atomic_t freehit;
63 atomic_t freemiss;
64
65 /*
66 * If debugging is enabled, then the allocator can add additional
67 * fields and/or padding to every object. 'size' contains the total
68 * object size including these internal fields, while 'obj_offset'
69 * and 'object_size' contain the offset to the user object and its
70 * size.
71 */
72 int obj_offset;
73 #endif /* CONFIG_DEBUG_SLAB */
74
75 #ifdef CONFIG_KASAN
76 struct kasan_cache kasan_info;
77 #endif
78
79 #ifdef CONFIG_SLAB_FREELIST_RANDOM
80 unsigned int *random_seq;
81 #endif
82
83 unsigned int useroffset; /* Usercopy region offset */
84 unsigned int usersize; /* Usercopy region size */
85
86 struct kmem_cache_node *node[MAX_NUMNODES];
87 };
88
nearest_obj(struct kmem_cache * cache,struct page * page,void * x)89 static inline void *nearest_obj(struct kmem_cache *cache, struct page *page,
90 void *x)
91 {
92 void *object = x - (x - page->s_mem) % cache->size;
93 void *last_object = page->s_mem + (cache->num - 1) * cache->size;
94
95 if (unlikely(object > last_object))
96 return last_object;
97 else
98 return object;
99 }
100
101 /*
102 * We want to avoid an expensive divide : (offset / cache->size)
103 * Using the fact that size is a constant for a particular cache,
104 * we can replace (offset / cache->size) by
105 * reciprocal_divide(offset, cache->reciprocal_buffer_size)
106 */
obj_to_index(const struct kmem_cache * cache,const struct page * page,void * obj)107 static inline unsigned int obj_to_index(const struct kmem_cache *cache,
108 const struct page *page, void *obj)
109 {
110 u32 offset = (obj - page->s_mem);
111 return reciprocal_divide(offset, cache->reciprocal_buffer_size);
112 }
113
objs_per_slab_page(const struct kmem_cache * cache,const struct page * page)114 static inline int objs_per_slab_page(const struct kmem_cache *cache,
115 const struct page *page)
116 {
117 return cache->num;
118 }
119
120 #endif /* _LINUX_SLAB_DEF_H */
121
