Commit | Line | Data |
---|---|---|
7ebd796f JA |
1 | /* |
2 | * Bitmap of bitmaps, where each layer is number-of-bits-per-word smaller than | |
3 | * the previous. Hence an 'axmap', since we axe each previous layer into a | |
4 | * much smaller piece. I swear, that is why it's named like that. It has | |
5 | * nothing to do with anything remotely narcissistic. | |
6 | * | |
7 | * A set bit at layer N indicates a full word at layer N-1, and so forth. As | |
de8f6de9 | 8 | * the bitmap becomes progressively more full, checking for existence |
7ebd796f JA |
9 | * becomes cheaper (since fewer layers are walked, making it a lot more |
10 | * cache friendly) and locating the next free space likewise. | |
11 | * | |
12 | * Axmaps get pretty close to optimal (1 bit per block) space usage, since | |
13 | * layers quickly diminish in size. Doing the size math is straight forward, | |
14 | * since we have log64(blocks) layers of maps. For 20000 blocks, overhead | |
15 | * is roughly 1.9%, or 1.019 bits per block. The number quickly converges | |
16 | * towards 1.0158, or 1.58% of overhead. | |
17 | */ | |
18 | #include <stdio.h> | |
19 | #include <stdlib.h> | |
20 | #include <string.h> | |
21 | #include <assert.h> | |
22 | ||
23 | #include "../arch/arch.h" | |
24 | #include "axmap.h" | |
7ebd796f JA |
25 | #include "../minmax.h" |
26 | ||
27 | #if BITS_PER_LONG == 64 | |
28 | #define UNIT_SHIFT 6 | |
29 | #elif BITS_PER_LONG == 32 | |
30 | #define UNIT_SHIFT 5 | |
31 | #else | |
32 | #error "Number of arch bits unknown" | |
33 | #endif | |
34 | ||
e6f735f0 | 35 | #define BLOCKS_PER_UNIT (1U << UNIT_SHIFT) |
7ebd796f JA |
36 | #define BLOCKS_PER_UNIT_MASK (BLOCKS_PER_UNIT - 1) |
37 | ||
38 | #define firstfree_valid(b) ((b)->first_free != (uint64_t) -1) | |
39 | ||
76dd186e JA |
40 | static const unsigned long bit_masks[] = { |
41 | 0x0000000000000000, 0x0000000000000001, 0x0000000000000003, 0x0000000000000007, | |
42 | 0x000000000000000f, 0x000000000000001f, 0x000000000000003f, 0x000000000000007f, | |
43 | 0x00000000000000ff, 0x00000000000001ff, 0x00000000000003ff, 0x00000000000007ff, | |
44 | 0x0000000000000fff, 0x0000000000001fff, 0x0000000000003fff, 0x0000000000007fff, | |
45 | 0x000000000000ffff, 0x000000000001ffff, 0x000000000003ffff, 0x000000000007ffff, | |
46 | 0x00000000000fffff, 0x00000000001fffff, 0x00000000003fffff, 0x00000000007fffff, | |
47 | 0x0000000000ffffff, 0x0000000001ffffff, 0x0000000003ffffff, 0x0000000007ffffff, | |
48 | 0x000000000fffffff, 0x000000001fffffff, 0x000000003fffffff, 0x000000007fffffff, | |
49 | 0x00000000ffffffff, | |
50 | #if BITS_PER_LONG == 64 | |
51 | 0x00000001ffffffff, 0x00000003ffffffff, 0x00000007ffffffff, 0x0000000fffffffff, | |
52 | 0x0000001fffffffff, 0x0000003fffffffff, 0x0000007fffffffff, 0x000000ffffffffff, | |
53 | 0x000001ffffffffff, 0x000003ffffffffff, 0x000007ffffffffff, 0x00000fffffffffff, | |
54 | 0x00001fffffffffff, 0x00003fffffffffff, 0x00007fffffffffff, 0x0000ffffffffffff, | |
55 | 0x0001ffffffffffff, 0x0003ffffffffffff, 0x0007ffffffffffff, 0x000fffffffffffff, | |
56 | 0x001fffffffffffff, 0x003fffffffffffff, 0x007fffffffffffff, 0x00ffffffffffffff, | |
57 | 0x01ffffffffffffff, 0x03ffffffffffffff, 0x07ffffffffffffff, 0x0fffffffffffffff, | |
58 | 0x1fffffffffffffff, 0x3fffffffffffffff, 0x7fffffffffffffff, 0xffffffffffffffff | |
59 | #endif | |
60 | }; | |
61 | ||
7ebd796f JA |
62 | struct axmap_level { |
63 | int level; | |
64 | unsigned long map_size; | |
65 | unsigned long *map; | |
66 | }; | |
67 | ||
68 | struct axmap { | |
69 | unsigned int nr_levels; | |
70 | struct axmap_level *levels; | |
71 | uint64_t first_free; | |
47d94b0b | 72 | uint64_t nr_bits; |
7ebd796f JA |
73 | }; |
74 | ||
76dd186e | 75 | static inline unsigned long ulog64(unsigned long val, unsigned int log) |
7ebd796f JA |
76 | { |
77 | while (log-- && val) | |
78 | val >>= UNIT_SHIFT; | |
79 | ||
80 | return val; | |
81 | } | |
82 | ||
83 | void axmap_reset(struct axmap *axmap) | |
84 | { | |
85 | int i; | |
86 | ||
87 | for (i = 0; i < axmap->nr_levels; i++) { | |
88 | struct axmap_level *al = &axmap->levels[i]; | |
89 | ||
90 | memset(al->map, 0, al->map_size * sizeof(unsigned long)); | |
91 | } | |
17f0fd39 JA |
92 | |
93 | axmap->first_free = 0; | |
7ebd796f JA |
94 | } |
95 | ||
96 | void axmap_free(struct axmap *axmap) | |
97 | { | |
98 | unsigned int i; | |
99 | ||
100 | if (!axmap) | |
101 | return; | |
102 | ||
103 | for (i = 0; i < axmap->nr_levels; i++) | |
aded30f7 | 104 | free(axmap->levels[i].map); |
7ebd796f | 105 | |
aded30f7 JA |
106 | free(axmap->levels); |
107 | free(axmap); | |
7ebd796f JA |
108 | } |
109 | ||
110 | struct axmap *axmap_new(unsigned long nr_bits) | |
111 | { | |
112 | struct axmap *axmap; | |
113 | unsigned int i, levels; | |
114 | ||
aded30f7 | 115 | axmap = malloc(sizeof(*axmap)); |
7ebd796f JA |
116 | if (!axmap) |
117 | return NULL; | |
118 | ||
119 | levels = 1; | |
120 | i = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
121 | while (i > 1) { | |
122 | i = (i + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
123 | levels++; | |
124 | } | |
125 | ||
126 | axmap->nr_levels = levels; | |
2404b2c3 | 127 | axmap->levels = calloc(axmap->nr_levels, sizeof(struct axmap_level)); |
47d94b0b | 128 | axmap->nr_bits = nr_bits; |
7ebd796f JA |
129 | |
130 | for (i = 0; i < axmap->nr_levels; i++) { | |
131 | struct axmap_level *al = &axmap->levels[i]; | |
132 | ||
133 | al->level = i; | |
134 | al->map_size = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
aded30f7 | 135 | al->map = malloc(al->map_size * sizeof(unsigned long)); |
7ebd796f JA |
136 | if (!al->map) |
137 | goto err; | |
138 | ||
139 | nr_bits = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
140 | } | |
141 | ||
142 | axmap_reset(axmap); | |
143 | return axmap; | |
144 | err: | |
145 | for (i = 0; i < axmap->nr_levels; i++) | |
146 | if (axmap->levels[i].map) | |
aded30f7 | 147 | free(axmap->levels[i].map); |
7ebd796f | 148 | |
aded30f7 | 149 | free(axmap->levels); |
bb1116fe | 150 | free(axmap); |
7ebd796f JA |
151 | return NULL; |
152 | } | |
153 | ||
e39c0676 JA |
154 | static bool axmap_handler(struct axmap *axmap, uint64_t bit_nr, |
155 | bool (*func)(struct axmap_level *, unsigned long, unsigned int, | |
7ebd796f JA |
156 | void *), void *data) |
157 | { | |
158 | struct axmap_level *al; | |
159 | int i; | |
160 | ||
161 | for (i = 0; i < axmap->nr_levels; i++) { | |
162 | unsigned long index = ulog64(bit_nr, i); | |
163 | unsigned long offset = index >> UNIT_SHIFT; | |
164 | unsigned int bit = index & BLOCKS_PER_UNIT_MASK; | |
165 | ||
166 | al = &axmap->levels[i]; | |
167 | ||
168 | if (func(al, offset, bit, data)) | |
e39c0676 | 169 | return true; |
7ebd796f JA |
170 | } |
171 | ||
e39c0676 | 172 | return false; |
7ebd796f JA |
173 | } |
174 | ||
e39c0676 JA |
175 | static bool axmap_handler_topdown(struct axmap *axmap, uint64_t bit_nr, |
176 | bool (*func)(struct axmap_level *, unsigned long, unsigned int, void *), | |
7ebd796f JA |
177 | void *data) |
178 | { | |
179 | struct axmap_level *al; | |
76dd186e | 180 | int i; |
7ebd796f JA |
181 | |
182 | for (i = axmap->nr_levels - 1; i >= 0; i--) { | |
76dd186e | 183 | unsigned long index = ulog64(bit_nr, i); |
7ebd796f JA |
184 | unsigned long offset = index >> UNIT_SHIFT; |
185 | unsigned int bit = index & BLOCKS_PER_UNIT_MASK; | |
186 | ||
187 | al = &axmap->levels[i]; | |
188 | ||
189 | if (func(al, offset, bit, data)) | |
e39c0676 | 190 | return true; |
7ebd796f JA |
191 | } |
192 | ||
e39c0676 | 193 | return false; |
7ebd796f JA |
194 | } |
195 | ||
e39c0676 | 196 | static bool axmap_clear_fn(struct axmap_level *al, unsigned long offset, |
7ebd796f JA |
197 | unsigned int bit, void *unused) |
198 | { | |
199 | if (!(al->map[offset] & (1UL << bit))) | |
e39c0676 | 200 | return true; |
7ebd796f JA |
201 | |
202 | al->map[offset] &= ~(1UL << bit); | |
e39c0676 | 203 | return false; |
7ebd796f JA |
204 | } |
205 | ||
206 | void axmap_clear(struct axmap *axmap, uint64_t bit_nr) | |
207 | { | |
208 | axmap_handler(axmap, bit_nr, axmap_clear_fn, NULL); | |
2b2fa7f5 JA |
209 | |
210 | if (bit_nr < axmap->first_free) | |
211 | axmap->first_free = bit_nr; | |
7ebd796f JA |
212 | } |
213 | ||
214 | struct axmap_set_data { | |
215 | unsigned int nr_bits; | |
216 | unsigned int set_bits; | |
7ebd796f JA |
217 | }; |
218 | ||
e39c0676 | 219 | static bool axmap_set_fn(struct axmap_level *al, unsigned long offset, |
7ebd796f JA |
220 | unsigned int bit, void *__data) |
221 | { | |
222 | struct axmap_set_data *data = __data; | |
223 | unsigned long mask, overlap; | |
224 | unsigned int nr_bits; | |
225 | ||
226 | nr_bits = min(data->nr_bits, BLOCKS_PER_UNIT - bit); | |
227 | ||
228 | mask = bit_masks[nr_bits] << bit; | |
229 | ||
230 | /* | |
231 | * Mask off any potential overlap, only sets contig regions | |
232 | */ | |
233 | overlap = al->map[offset] & mask; | |
09d6bf09 | 234 | if (overlap == mask) |
e39c0676 | 235 | return true; |
7ebd796f | 236 | |
8cd5a2fd JA |
237 | if (overlap) { |
238 | const int __bit = ffz(~overlap); | |
7ebd796f | 239 | |
c2e48e0e JA |
240 | nr_bits = __bit - bit; |
241 | if (!nr_bits) | |
8cd5a2fd JA |
242 | return true; |
243 | ||
8cd5a2fd | 244 | mask = bit_masks[nr_bits] << bit; |
7ebd796f JA |
245 | } |
246 | ||
247 | assert(mask); | |
248 | assert(!(al->map[offset] & mask)); | |
7ebd796f JA |
249 | al->map[offset] |= mask; |
250 | ||
251 | if (!al->level) | |
252 | data->set_bits = nr_bits; | |
253 | ||
254 | data->nr_bits = 1; | |
255 | return al->map[offset] != -1UL; | |
256 | } | |
257 | ||
258 | static void __axmap_set(struct axmap *axmap, uint64_t bit_nr, | |
259 | struct axmap_set_data *data) | |
260 | { | |
261 | unsigned int set_bits, nr_bits = data->nr_bits; | |
262 | ||
263 | if (axmap->first_free >= bit_nr && | |
264 | axmap->first_free < bit_nr + data->nr_bits) | |
265 | axmap->first_free = -1ULL; | |
266 | ||
47d94b0b JA |
267 | if (bit_nr > axmap->nr_bits) |
268 | return; | |
269 | else if (bit_nr + nr_bits > axmap->nr_bits) | |
270 | nr_bits = axmap->nr_bits - bit_nr; | |
271 | ||
7ebd796f JA |
272 | set_bits = 0; |
273 | while (nr_bits) { | |
274 | axmap_handler(axmap, bit_nr, axmap_set_fn, data); | |
275 | set_bits += data->set_bits; | |
276 | ||
0bfdf9f1 JA |
277 | if (!data->set_bits || |
278 | data->set_bits != (BLOCKS_PER_UNIT - nr_bits)) | |
7ebd796f JA |
279 | break; |
280 | ||
281 | nr_bits -= data->set_bits; | |
282 | bit_nr += data->set_bits; | |
283 | ||
284 | data->nr_bits = nr_bits; | |
7ebd796f JA |
285 | } |
286 | ||
287 | data->set_bits = set_bits; | |
288 | } | |
289 | ||
290 | void axmap_set(struct axmap *axmap, uint64_t bit_nr) | |
291 | { | |
292 | struct axmap_set_data data = { .nr_bits = 1, }; | |
293 | ||
294 | __axmap_set(axmap, bit_nr, &data); | |
295 | } | |
296 | ||
e39c0676 JA |
297 | unsigned int axmap_set_nr(struct axmap *axmap, uint64_t bit_nr, |
298 | unsigned int nr_bits) | |
7ebd796f | 299 | { |
0bfdf9f1 JA |
300 | unsigned int set_bits = 0; |
301 | ||
302 | do { | |
09d6bf09 | 303 | struct axmap_set_data data = { .nr_bits = nr_bits, }; |
0bfdf9f1 JA |
304 | unsigned int max_bits, this_set; |
305 | ||
306 | max_bits = BLOCKS_PER_UNIT - (bit_nr & BLOCKS_PER_UNIT_MASK); | |
307 | if (max_bits < nr_bits) | |
308 | data.nr_bits = max_bits; | |
309 | ||
310 | this_set = data.nr_bits; | |
311 | __axmap_set(axmap, bit_nr, &data); | |
312 | set_bits += data.set_bits; | |
313 | if (data.set_bits != this_set) | |
314 | break; | |
7ebd796f | 315 | |
0bfdf9f1 JA |
316 | nr_bits -= data.set_bits; |
317 | bit_nr += data.set_bits; | |
318 | } while (nr_bits); | |
319 | ||
320 | return set_bits; | |
7ebd796f JA |
321 | } |
322 | ||
e39c0676 JA |
323 | static bool axmap_isset_fn(struct axmap_level *al, unsigned long offset, |
324 | unsigned int bit, void *unused) | |
7ebd796f JA |
325 | { |
326 | return (al->map[offset] & (1UL << bit)) != 0; | |
327 | } | |
328 | ||
e39c0676 | 329 | bool axmap_isset(struct axmap *axmap, uint64_t bit_nr) |
7ebd796f | 330 | { |
ac569176 JA |
331 | if (bit_nr <= axmap->nr_bits) |
332 | return axmap_handler_topdown(axmap, bit_nr, axmap_isset_fn, NULL); | |
47d94b0b | 333 | |
e39c0676 | 334 | return false; |
7ebd796f JA |
335 | } |
336 | ||
337 | static uint64_t axmap_find_first_free(struct axmap *axmap, unsigned int level, | |
338 | uint64_t index) | |
339 | { | |
731ef4c7 | 340 | uint64_t ret = -1ULL; |
7ebd796f | 341 | unsigned long j; |
731ef4c7 | 342 | int i; |
7ebd796f JA |
343 | |
344 | /* | |
345 | * Start at the bottom, then converge towards first free bit at the top | |
346 | */ | |
347 | for (i = level; i >= 0; i--) { | |
348 | struct axmap_level *al = &axmap->levels[i]; | |
349 | ||
731ef4c7 JA |
350 | /* |
351 | * Clear 'ret', this is a bug condition. | |
352 | */ | |
7ebd796f | 353 | if (index >= al->map_size) { |
731ef4c7 | 354 | ret = -1ULL; |
7ebd796f JA |
355 | break; |
356 | } | |
357 | ||
358 | for (j = index; j < al->map_size; j++) { | |
359 | if (al->map[j] == -1UL) | |
360 | continue; | |
361 | ||
362 | /* | |
363 | * First free bit here is our index into the first | |
364 | * free bit at the next higher level | |
365 | */ | |
731ef4c7 | 366 | ret = index = (j << UNIT_SHIFT) + ffz(al->map[j]); |
7ebd796f JA |
367 | break; |
368 | } | |
369 | } | |
370 | ||
47d94b0b JA |
371 | if (ret < axmap->nr_bits) |
372 | return ret; | |
373 | ||
374 | return (uint64_t) -1ULL; | |
7ebd796f JA |
375 | } |
376 | ||
99b9c534 | 377 | static uint64_t axmap_first_free(struct axmap *axmap) |
7ebd796f | 378 | { |
2b2fa7f5 JA |
379 | if (!firstfree_valid(axmap)) |
380 | axmap->first_free = axmap_find_first_free(axmap, axmap->nr_levels - 1, 0); | |
7ebd796f | 381 | |
ac569176 | 382 | return axmap->first_free; |
7ebd796f JA |
383 | } |
384 | ||
385 | struct axmap_next_free_data { | |
386 | unsigned int level; | |
387 | unsigned long offset; | |
388 | uint64_t bit; | |
389 | }; | |
390 | ||
e39c0676 | 391 | static bool axmap_next_free_fn(struct axmap_level *al, unsigned long offset, |
7ebd796f JA |
392 | unsigned int bit, void *__data) |
393 | { | |
394 | struct axmap_next_free_data *data = __data; | |
53737ae0 | 395 | uint64_t mask = ~bit_masks[(data->bit + 1) & BLOCKS_PER_UNIT_MASK]; |
7ebd796f | 396 | |
53737ae0 | 397 | if (!(mask & ~al->map[offset])) |
e39c0676 | 398 | return false; |
7ebd796f JA |
399 | |
400 | if (al->map[offset] != -1UL) { | |
401 | data->level = al->level; | |
402 | data->offset = offset; | |
e39c0676 | 403 | return true; |
7ebd796f JA |
404 | } |
405 | ||
406 | data->bit = (data->bit + BLOCKS_PER_UNIT - 1) / BLOCKS_PER_UNIT; | |
e39c0676 | 407 | return false; |
7ebd796f JA |
408 | } |
409 | ||
410 | /* | |
411 | * 'bit_nr' is already set. Find the next free bit after this one. | |
412 | */ | |
413 | uint64_t axmap_next_free(struct axmap *axmap, uint64_t bit_nr) | |
414 | { | |
415 | struct axmap_next_free_data data = { .level = -1U, .bit = bit_nr, }; | |
53737ae0 | 416 | uint64_t ret; |
7ebd796f | 417 | |
ac569176 JA |
418 | if (firstfree_valid(axmap) && bit_nr < axmap->first_free) |
419 | return axmap->first_free; | |
12bde369 | 420 | |
ac569176 JA |
421 | if (!axmap_handler(axmap, bit_nr, axmap_next_free_fn, &data)) |
422 | return axmap_first_free(axmap); | |
7ebd796f JA |
423 | |
424 | assert(data.level != -1U); | |
425 | ||
53737ae0 JA |
426 | /* |
427 | * In the rare case that the map is unaligned, we might end up | |
428 | * finding an offset that's beyond the valid end. For that case, | |
429 | * find the first free one, the map is practically full. | |
430 | */ | |
431 | ret = axmap_find_first_free(axmap, data.level, data.offset); | |
ac569176 | 432 | if (ret != -1ULL) |
53737ae0 JA |
433 | return ret; |
434 | ||
ac569176 | 435 | return axmap_first_free(axmap); |
7ebd796f | 436 | } |