1 /* SPDX-License-Identifier: MIT */
2 /*
3 * Copyright © 2021 Intel Corporation
4 */
5
6 #ifndef __DRM_BUDDY_H__
7 #define __DRM_BUDDY_H__
8
9 #include <linux/bitops.h>
10 #include <linux/list.h>
11 #include <linux/slab.h>
12 #include <linux/sched.h>
13
14 #include <drm/drm_print.h>
15
16 #define range_overflows(start, size, max) ({ \
17 typeof(start) start__ = (start); \
18 typeof(size) size__ = (size); \
19 typeof(max) max__ = (max); \
20 (void)(&start__ == &size__); \
21 (void)(&start__ == &max__); \
22 start__ >= max__ || size__ > max__ - start__; \
23 })
24
25 #define DRM_BUDDY_RANGE_ALLOCATION BIT(0)
26 #define DRM_BUDDY_TOPDOWN_ALLOCATION BIT(1)
27 #define DRM_BUDDY_CONTIGUOUS_ALLOCATION BIT(2)
28
29 struct drm_buddy_block {
30 #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
31 #define DRM_BUDDY_HEADER_STATE GENMASK_ULL(11, 10)
32 #define DRM_BUDDY_ALLOCATED (1 << 10)
33 #define DRM_BUDDY_FREE (2 << 10)
34 #define DRM_BUDDY_SPLIT (3 << 10)
35 /* Free to be used, if needed in the future */
36 #define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
37 #define DRM_BUDDY_HEADER_ORDER GENMASK_ULL(5, 0)
38 u64 header;
39
40 struct drm_buddy_block *left;
41 struct drm_buddy_block *right;
42 struct drm_buddy_block *parent;
43
44 void *private; /* owned by creator */
45
46 /*
47 * While the block is allocated by the user through drm_buddy_alloc*,
48 * the user has ownership of the link, for example to maintain within
49 * a list, if so desired. As soon as the block is freed with
50 * drm_buddy_free* ownership is given back to the mm.
51 */
52 struct list_head link;
53 struct list_head tmp_link;
54 };
55
56 /* Order-zero must be at least PAGE_SIZE */
57 #define DRM_BUDDY_MAX_ORDER (63 - PAGE_SHIFT)
58
59 /*
60 * Binary Buddy System.
61 *
62 * Locking should be handled by the user, a simple mutex around
63 * drm_buddy_alloc* and drm_buddy_free* should suffice.
64 */
65 struct drm_buddy {
66 /* Maintain a free list for each order. */
67 struct list_head *free_list;
68
69 /*
70 * Maintain explicit binary tree(s) to track the allocation of the
71 * address space. This gives us a simple way of finding a buddy block
72 * and performing the potentially recursive merge step when freeing a
73 * block. Nodes are either allocated or free, in which case they will
74 * also exist on the respective free list.
75 */
76 struct drm_buddy_block **roots;
77
78 /*
79 * Anything from here is public, and remains static for the lifetime of
80 * the mm. Everything above is considered do-not-touch.
81 */
82 unsigned int n_roots;
83 unsigned int max_order;
84
85 /* Must be at least PAGE_SIZE */
86 u64 chunk_size;
87 u64 size;
88 u64 avail;
89 };
90
91 static inline u64
drm_buddy_block_offset(struct drm_buddy_block * block)92 drm_buddy_block_offset(struct drm_buddy_block *block)
93 {
94 return block->header & DRM_BUDDY_HEADER_OFFSET;
95 }
96
97 static inline unsigned int
drm_buddy_block_order(struct drm_buddy_block * block)98 drm_buddy_block_order(struct drm_buddy_block *block)
99 {
100 return block->header & DRM_BUDDY_HEADER_ORDER;
101 }
102
103 static inline unsigned int
drm_buddy_block_state(struct drm_buddy_block * block)104 drm_buddy_block_state(struct drm_buddy_block *block)
105 {
106 return block->header & DRM_BUDDY_HEADER_STATE;
107 }
108
109 static inline bool
drm_buddy_block_is_allocated(struct drm_buddy_block * block)110 drm_buddy_block_is_allocated(struct drm_buddy_block *block)
111 {
112 return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
113 }
114
115 static inline bool
drm_buddy_block_is_free(struct drm_buddy_block * block)116 drm_buddy_block_is_free(struct drm_buddy_block *block)
117 {
118 return drm_buddy_block_state(block) == DRM_BUDDY_FREE;
119 }
120
121 static inline bool
drm_buddy_block_is_split(struct drm_buddy_block * block)122 drm_buddy_block_is_split(struct drm_buddy_block *block)
123 {
124 return drm_buddy_block_state(block) == DRM_BUDDY_SPLIT;
125 }
126
127 static inline u64
drm_buddy_block_size(struct drm_buddy * mm,struct drm_buddy_block * block)128 drm_buddy_block_size(struct drm_buddy *mm,
129 struct drm_buddy_block *block)
130 {
131 return mm->chunk_size << drm_buddy_block_order(block);
132 }
133
134 int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size);
135
136 void drm_buddy_fini(struct drm_buddy *mm);
137
138 struct drm_buddy_block *
139 drm_get_buddy(struct drm_buddy_block *block);
140
141 int drm_buddy_alloc_blocks(struct drm_buddy *mm,
142 u64 start, u64 end, u64 size,
143 u64 min_page_size,
144 struct list_head *blocks,
145 unsigned long flags);
146
147 int drm_buddy_block_trim(struct drm_buddy *mm,
148 u64 new_size,
149 struct list_head *blocks);
150
151 void drm_buddy_free_block(struct drm_buddy *mm, struct drm_buddy_block *block);
152
153 void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects);
154
155 void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
156 void drm_buddy_block_print(struct drm_buddy *mm,
157 struct drm_buddy_block *block,
158 struct drm_printer *p);
159 #endif
160