1
2 #include <linux/export.h>
3 #include <linux/generic-radix-tree.h>
4 #include <linux/gfp.h>
5 #include <linux/kmemleak.h>
6
7 #define GENRADIX_ARY (PAGE_SIZE / sizeof(struct genradix_node *))
8 #define GENRADIX_ARY_SHIFT ilog2(GENRADIX_ARY)
9
10 struct genradix_node {
11 union {
12 /* Interior node: */
13 struct genradix_node *children[GENRADIX_ARY];
14
15 /* Leaf: */
16 u8 data[PAGE_SIZE];
17 };
18 };
19
genradix_depth_shift(unsigned depth)20 static inline int genradix_depth_shift(unsigned depth)
21 {
22 return PAGE_SHIFT + GENRADIX_ARY_SHIFT * depth;
23 }
24
25 /*
26 * Returns size (of data, in bytes) that a tree of a given depth holds:
27 */
genradix_depth_size(unsigned depth)28 static inline size_t genradix_depth_size(unsigned depth)
29 {
30 return 1UL << genradix_depth_shift(depth);
31 }
32
33 /* depth that's needed for a genradix that can address up to ULONG_MAX: */
34 #define GENRADIX_MAX_DEPTH \
35 DIV_ROUND_UP(BITS_PER_LONG - PAGE_SHIFT, GENRADIX_ARY_SHIFT)
36
37 #define GENRADIX_DEPTH_MASK \
38 ((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1))
39
genradix_root_to_depth(struct genradix_root * r)40 static inline unsigned genradix_root_to_depth(struct genradix_root *r)
41 {
42 return (unsigned long) r & GENRADIX_DEPTH_MASK;
43 }
44
genradix_root_to_node(struct genradix_root * r)45 static inline struct genradix_node *genradix_root_to_node(struct genradix_root *r)
46 {
47 return (void *) ((unsigned long) r & ~GENRADIX_DEPTH_MASK);
48 }
49
50 /*
51 * Returns pointer to the specified byte @offset within @radix, or NULL if not
52 * allocated
53 */
__genradix_ptr(struct __genradix * radix,size_t offset)54 void *__genradix_ptr(struct __genradix *radix, size_t offset)
55 {
56 struct genradix_root *r = READ_ONCE(radix->root);
57 struct genradix_node *n = genradix_root_to_node(r);
58 unsigned level = genradix_root_to_depth(r);
59
60 if (ilog2(offset) >= genradix_depth_shift(level))
61 return NULL;
62
63 while (1) {
64 if (!n)
65 return NULL;
66 if (!level)
67 break;
68
69 level--;
70
71 n = n->children[offset >> genradix_depth_shift(level)];
72 offset &= genradix_depth_size(level) - 1;
73 }
74
75 return &n->data[offset];
76 }
77 EXPORT_SYMBOL(__genradix_ptr);
78
genradix_alloc_node(gfp_t gfp_mask)79 static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask)
80 {
81 struct genradix_node *node;
82
83 node = (struct genradix_node *)__get_free_page(gfp_mask|__GFP_ZERO);
84
85 /*
86 * We're using pages (not slab allocations) directly for kernel data
87 * structures, so we need to explicitly inform kmemleak of them in order
88 * to avoid false positive memory leak reports.
89 */
90 kmemleak_alloc(node, PAGE_SIZE, 1, gfp_mask);
91 return node;
92 }
93
genradix_free_node(struct genradix_node * node)94 static inline void genradix_free_node(struct genradix_node *node)
95 {
96 kmemleak_free(node);
97 free_page((unsigned long)node);
98 }
99
100 /*
101 * Returns pointer to the specified byte @offset within @radix, allocating it if
102 * necessary - newly allocated slots are always zeroed out:
103 */
__genradix_ptr_alloc(struct __genradix * radix,size_t offset,gfp_t gfp_mask)104 void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset,
105 gfp_t gfp_mask)
106 {
107 struct genradix_root *v = READ_ONCE(radix->root);
108 struct genradix_node *n, *new_node = NULL;
109 unsigned level;
110
111 /* Increase tree depth if necessary: */
112 while (1) {
113 struct genradix_root *r = v, *new_root;
114
115 n = genradix_root_to_node(r);
116 level = genradix_root_to_depth(r);
117
118 if (n && ilog2(offset) < genradix_depth_shift(level))
119 break;
120
121 if (!new_node) {
122 new_node = genradix_alloc_node(gfp_mask);
123 if (!new_node)
124 return NULL;
125 }
126
127 new_node->children[0] = n;
128 new_root = ((struct genradix_root *)
129 ((unsigned long) new_node | (n ? level + 1 : 0)));
130
131 if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) {
132 v = new_root;
133 new_node = NULL;
134 }
135 }
136
137 while (level--) {
138 struct genradix_node **p =
139 &n->children[offset >> genradix_depth_shift(level)];
140 offset &= genradix_depth_size(level) - 1;
141
142 n = READ_ONCE(*p);
143 if (!n) {
144 if (!new_node) {
145 new_node = genradix_alloc_node(gfp_mask);
146 if (!new_node)
147 return NULL;
148 }
149
150 if (!(n = cmpxchg_release(p, NULL, new_node)))
151 swap(n, new_node);
152 }
153 }
154
155 if (new_node)
156 genradix_free_node(new_node);
157
158 return &n->data[offset];
159 }
160 EXPORT_SYMBOL(__genradix_ptr_alloc);
161
__genradix_iter_peek(struct genradix_iter * iter,struct __genradix * radix,size_t objs_per_page)162 void *__genradix_iter_peek(struct genradix_iter *iter,
163 struct __genradix *radix,
164 size_t objs_per_page)
165 {
166 struct genradix_root *r;
167 struct genradix_node *n;
168 unsigned level, i;
169
170 if (iter->offset == SIZE_MAX)
171 return NULL;
172
173 restart:
174 r = READ_ONCE(radix->root);
175 if (!r)
176 return NULL;
177
178 n = genradix_root_to_node(r);
179 level = genradix_root_to_depth(r);
180
181 if (ilog2(iter->offset) >= genradix_depth_shift(level))
182 return NULL;
183
184 while (level) {
185 level--;
186
187 i = (iter->offset >> genradix_depth_shift(level)) &
188 (GENRADIX_ARY - 1);
189
190 while (!n->children[i]) {
191 size_t objs_per_ptr = genradix_depth_size(level);
192
193 if (iter->offset + objs_per_ptr < iter->offset) {
194 iter->offset = SIZE_MAX;
195 iter->pos = SIZE_MAX;
196 return NULL;
197 }
198
199 i++;
200 iter->offset = round_down(iter->offset + objs_per_ptr,
201 objs_per_ptr);
202 iter->pos = (iter->offset >> PAGE_SHIFT) *
203 objs_per_page;
204 if (i == GENRADIX_ARY)
205 goto restart;
206 }
207
208 n = n->children[i];
209 }
210
211 return &n->data[iter->offset & (PAGE_SIZE - 1)];
212 }
213 EXPORT_SYMBOL(__genradix_iter_peek);
214
genradix_free_recurse(struct genradix_node * n,unsigned level)215 static void genradix_free_recurse(struct genradix_node *n, unsigned level)
216 {
217 if (level) {
218 unsigned i;
219
220 for (i = 0; i < GENRADIX_ARY; i++)
221 if (n->children[i])
222 genradix_free_recurse(n->children[i], level - 1);
223 }
224
225 genradix_free_node(n);
226 }
227
__genradix_prealloc(struct __genradix * radix,size_t size,gfp_t gfp_mask)228 int __genradix_prealloc(struct __genradix *radix, size_t size,
229 gfp_t gfp_mask)
230 {
231 size_t offset;
232
233 for (offset = 0; offset < size; offset += PAGE_SIZE)
234 if (!__genradix_ptr_alloc(radix, offset, gfp_mask))
235 return -ENOMEM;
236
237 return 0;
238 }
239 EXPORT_SYMBOL(__genradix_prealloc);
240
__genradix_free(struct __genradix * radix)241 void __genradix_free(struct __genradix *radix)
242 {
243 struct genradix_root *r = xchg(&radix->root, NULL);
244
245 genradix_free_recurse(genradix_root_to_node(r),
246 genradix_root_to_depth(r));
247 }
248 EXPORT_SYMBOL(__genradix_free);
249