1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SLAB_DEF_H
3 #define _LINUX_SLAB_DEF_H
4
5 #include <linux/kfence.h>
6 #include <linux/reciprocal_div.h>
7
8 /*
9 * Definitions unique to the original Linux SLAB allocator.
10 */
11
12 struct kmem_cache {
13 struct array_cache __percpu *cpu_cache;
14
15 /* 1) Cache tunables. Protected by slab_mutex */
16 unsigned int batchcount;
17 unsigned int limit;
18 unsigned int shared;
19
20 unsigned int size;
21 struct reciprocal_value reciprocal_buffer_size;
22 /* 2) touched by every alloc & free from the backend */
23
24 slab_flags_t flags; /* constant flags */
25 unsigned int num; /* # of objs per slab */
26
27 /* 3) cache_grow/shrink */
28 /* order of pgs per slab (2^n) */
29 unsigned int gfporder;
30
31 /* force GFP flags, e.g. GFP_DMA */
32 gfp_t allocflags;
33
34 size_t colour; /* cache colouring range */
35 unsigned int colour_off; /* colour offset */
36 struct kmem_cache *freelist_cache;
37 unsigned int freelist_size;
38
39 /* constructor func */
40 void (*ctor)(void *obj);
41
42 /* 4) cache creation/removal */
43 const char *name;
44 struct list_head list;
45 int refcount;
46 int object_size;
47 int align;
48
49 /* 5) statistics */
50 #ifdef CONFIG_DEBUG_SLAB
51 unsigned long num_active;
52 unsigned long num_allocations;
53 unsigned long high_mark;
54 unsigned long grown;
55 unsigned long reaped;
56 unsigned long errors;
57 unsigned long max_freeable;
58 unsigned long node_allocs;
59 unsigned long node_frees;
60 unsigned long node_overflow;
61 atomic_t allochit;
62 atomic_t allocmiss;
63 atomic_t freehit;
64 atomic_t freemiss;
65
66 /*
67 * If debugging is enabled, then the allocator can add additional
68 * fields and/or padding to every object. 'size' contains the total
69 * object size including these internal fields, while 'obj_offset'
70 * and 'object_size' contain the offset to the user object and its
71 * size.
72 */
73 int obj_offset;
74 #endif /* CONFIG_DEBUG_SLAB */
75
76 #ifdef CONFIG_KASAN
77 struct kasan_cache kasan_info;
78 #endif
79
80 #ifdef CONFIG_SLAB_FREELIST_RANDOM
81 unsigned int *random_seq;
82 #endif
83
84 unsigned int useroffset; /* Usercopy region offset */
85 unsigned int usersize; /* Usercopy region size */
86
87 struct kmem_cache_node *node[MAX_NUMNODES];
88 };
89
nearest_obj(struct kmem_cache * cache,struct page * page,void * x)90 static inline void *nearest_obj(struct kmem_cache *cache, struct page *page,
91 void *x)
92 {
93 void *object = x - (x - page->s_mem) % cache->size;
94 void *last_object = page->s_mem + (cache->num - 1) * cache->size;
95
96 if (unlikely(object > last_object))
97 return last_object;
98 else
99 return object;
100 }
101
102 /*
103 * We want to avoid an expensive divide : (offset / cache->size)
104 * Using the fact that size is a constant for a particular cache,
105 * we can replace (offset / cache->size) by
106 * reciprocal_divide(offset, cache->reciprocal_buffer_size)
107 */
obj_to_index(const struct kmem_cache * cache,const struct page * page,void * obj)108 static inline unsigned int obj_to_index(const struct kmem_cache *cache,
109 const struct page *page, void *obj)
110 {
111 u32 offset = (obj - page->s_mem);
112 return reciprocal_divide(offset, cache->reciprocal_buffer_size);
113 }
114
objs_per_slab_page(const struct kmem_cache * cache,const struct page * page)115 static inline int objs_per_slab_page(const struct kmem_cache *cache,
116 const struct page *page)
117 {
118 if (is_kfence_address(page_address(page)))
119 return 1;
120 return cache->num;
121 }
122
123 #endif /* _LINUX_SLAB_DEF_H */
124