1 /*
2 * simple memory allocator, backed by mmap() so that it hands out memory
3 * that can be shared across processes and threads
4 */
5 #include <sys/mman.h>
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <assert.h>
9 #include <string.h>
10 #include <unistd.h>
11 #include <inttypes.h>
12 #include <sys/types.h>
13 #include <limits.h>
14 #include <fcntl.h>
15
16 #include "mutex.h"
17 #include "arch/arch.h"
18 #include "os/os.h"
19 #include "smalloc.h"
20
21 #define SMALLOC_REDZONE /* define to detect memory corruption */
22
23 #define SMALLOC_BPB 32 /* block size, bytes-per-bit in bitmap */
24 #define SMALLOC_BPI (sizeof(unsigned int) * 8)
25 #define SMALLOC_BPL (SMALLOC_BPB * SMALLOC_BPI)
26
27 #define INITIAL_SIZE 8192*1024 /* new pool size */
28 #define MAX_POOLS 128 /* maximum number of pools to setup */
29
30 #define SMALLOC_PRE_RED 0xdeadbeefU
31 #define SMALLOC_POST_RED 0x5aa55aa5U
32
33 unsigned int smalloc_pool_size = INITIAL_SIZE;
34 static const int int_mask = sizeof(int) - 1;
35
36 struct pool {
37 struct fio_mutex *lock; /* protects this pool */
38 void *map; /* map of blocks */
39 unsigned int *bitmap; /* blocks free/busy map */
40 size_t free_blocks; /* free blocks */
41 size_t nr_blocks; /* total blocks */
42 size_t next_non_full;
43 size_t mmap_size;
44 };
45
46 struct block_hdr {
47 size_t size;
48 #ifdef SMALLOC_REDZONE
49 unsigned int prered;
50 #endif
51 };
52
53 static struct pool mp[MAX_POOLS];
54 static unsigned int nr_pools;
55 static unsigned int last_pool;
56 static struct fio_rwlock *lock;
57
pool_lock(struct pool * pool)58 static inline void pool_lock(struct pool *pool)
59 {
60 fio_mutex_down(pool->lock);
61 }
62
pool_unlock(struct pool * pool)63 static inline void pool_unlock(struct pool *pool)
64 {
65 fio_mutex_up(pool->lock);
66 }
67
global_read_lock(void)68 static inline void global_read_lock(void)
69 {
70 fio_rwlock_read(lock);
71 }
72
global_read_unlock(void)73 static inline void global_read_unlock(void)
74 {
75 fio_rwlock_unlock(lock);
76 }
77
global_write_lock(void)78 static inline void global_write_lock(void)
79 {
80 fio_rwlock_write(lock);
81 }
82
global_write_unlock(void)83 static inline void global_write_unlock(void)
84 {
85 fio_rwlock_unlock(lock);
86 }
87
ptr_valid(struct pool * pool,void * ptr)88 static inline int ptr_valid(struct pool *pool, void *ptr)
89 {
90 unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;
91
92 return (ptr >= pool->map) && (ptr < pool->map + pool_size);
93 }
94
size_to_blocks(size_t size)95 static inline size_t size_to_blocks(size_t size)
96 {
97 return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
98 }
99
blocks_iter(struct pool * pool,unsigned int pool_idx,unsigned int idx,size_t nr_blocks,int (* func)(unsigned int * map,unsigned int mask))100 static int blocks_iter(struct pool *pool, unsigned int pool_idx,
101 unsigned int idx, size_t nr_blocks,
102 int (*func)(unsigned int *map, unsigned int mask))
103 {
104
105 while (nr_blocks) {
106 unsigned int this_blocks, mask;
107 unsigned int *map;
108
109 if (pool_idx >= pool->nr_blocks)
110 return 0;
111
112 map = &pool->bitmap[pool_idx];
113
114 this_blocks = nr_blocks;
115 if (this_blocks + idx > SMALLOC_BPI) {
116 this_blocks = SMALLOC_BPI - idx;
117 idx = SMALLOC_BPI - this_blocks;
118 }
119
120 if (this_blocks == SMALLOC_BPI)
121 mask = -1U;
122 else
123 mask = ((1U << this_blocks) - 1) << idx;
124
125 if (!func(map, mask))
126 return 0;
127
128 nr_blocks -= this_blocks;
129 idx = 0;
130 pool_idx++;
131 }
132
133 return 1;
134 }
135
mask_cmp(unsigned int * map,unsigned int mask)136 static int mask_cmp(unsigned int *map, unsigned int mask)
137 {
138 return !(*map & mask);
139 }
140
mask_clear(unsigned int * map,unsigned int mask)141 static int mask_clear(unsigned int *map, unsigned int mask)
142 {
143 assert((*map & mask) == mask);
144 *map &= ~mask;
145 return 1;
146 }
147
mask_set(unsigned int * map,unsigned int mask)148 static int mask_set(unsigned int *map, unsigned int mask)
149 {
150 assert(!(*map & mask));
151 *map |= mask;
152 return 1;
153 }
154
blocks_free(struct pool * pool,unsigned int pool_idx,unsigned int idx,size_t nr_blocks)155 static int blocks_free(struct pool *pool, unsigned int pool_idx,
156 unsigned int idx, size_t nr_blocks)
157 {
158 return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
159 }
160
set_blocks(struct pool * pool,unsigned int pool_idx,unsigned int idx,size_t nr_blocks)161 static void set_blocks(struct pool *pool, unsigned int pool_idx,
162 unsigned int idx, size_t nr_blocks)
163 {
164 blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
165 }
166
clear_blocks(struct pool * pool,unsigned int pool_idx,unsigned int idx,size_t nr_blocks)167 static void clear_blocks(struct pool *pool, unsigned int pool_idx,
168 unsigned int idx, size_t nr_blocks)
169 {
170 blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
171 }
172
find_next_zero(int word,int start)173 static int find_next_zero(int word, int start)
174 {
175 assert(word != -1U);
176 word >>= start;
177 return ffz(word) + start;
178 }
179
add_pool(struct pool * pool,unsigned int alloc_size)180 static int add_pool(struct pool *pool, unsigned int alloc_size)
181 {
182 int bitmap_blocks;
183 void *ptr;
184
185 #ifdef SMALLOC_REDZONE
186 alloc_size += sizeof(unsigned int);
187 #endif
188 alloc_size += sizeof(struct block_hdr);
189 if (alloc_size < INITIAL_SIZE)
190 alloc_size = INITIAL_SIZE;
191
192 /* round up to nearest full number of blocks */
193 alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
194 bitmap_blocks = alloc_size / SMALLOC_BPL;
195 alloc_size += bitmap_blocks * sizeof(unsigned int);
196 pool->mmap_size = alloc_size;
197
198 pool->nr_blocks = bitmap_blocks;
199 pool->free_blocks = bitmap_blocks * SMALLOC_BPB;
200
201 ptr = mmap(NULL, alloc_size, PROT_READ|PROT_WRITE,
202 MAP_SHARED | OS_MAP_ANON, -1, 0);
203 if (ptr == MAP_FAILED)
204 goto out_fail;
205
206 memset(ptr, 0, alloc_size);
207 pool->map = ptr;
208 pool->bitmap = (void *) ptr + (pool->nr_blocks * SMALLOC_BPL);
209
210 pool->lock = fio_mutex_init(FIO_MUTEX_UNLOCKED);
211 if (!pool->lock)
212 goto out_fail;
213
214 nr_pools++;
215 return 0;
216 out_fail:
217 fprintf(stderr, "smalloc: failed adding pool\n");
218 if (pool->map)
219 munmap(pool->map, pool->mmap_size);
220 return 1;
221 }
222
sinit(void)223 void sinit(void)
224 {
225 int ret;
226
227 lock = fio_rwlock_init();
228 ret = add_pool(&mp[0], INITIAL_SIZE);
229 assert(!ret);
230 }
231
cleanup_pool(struct pool * pool)232 static void cleanup_pool(struct pool *pool)
233 {
234 /*
235 * This will also remove the temporary file we used as a backing
236 * store, it was already unlinked
237 */
238 munmap(pool->map, pool->mmap_size);
239
240 if (pool->lock)
241 fio_mutex_remove(pool->lock);
242 }
243
scleanup(void)244 void scleanup(void)
245 {
246 unsigned int i;
247
248 for (i = 0; i < nr_pools; i++)
249 cleanup_pool(&mp[i]);
250
251 if (lock)
252 fio_rwlock_remove(lock);
253 }
254
255 #ifdef SMALLOC_REDZONE
postred_ptr(struct block_hdr * hdr)256 static void *postred_ptr(struct block_hdr *hdr)
257 {
258 uintptr_t ptr;
259
260 ptr = (uintptr_t) hdr + hdr->size - sizeof(unsigned int);
261 ptr = (ptr + int_mask) & ~int_mask;
262
263 return (void *) ptr;
264 }
265
fill_redzone(struct block_hdr * hdr)266 static void fill_redzone(struct block_hdr *hdr)
267 {
268 unsigned int *postred = postred_ptr(hdr);
269
270 hdr->prered = SMALLOC_PRE_RED;
271 *postred = SMALLOC_POST_RED;
272 }
273
sfree_check_redzone(struct block_hdr * hdr)274 static void sfree_check_redzone(struct block_hdr *hdr)
275 {
276 unsigned int *postred = postred_ptr(hdr);
277
278 if (hdr->prered != SMALLOC_PRE_RED) {
279 fprintf(stderr, "smalloc pre redzone destroyed!\n");
280 fprintf(stderr, " ptr=%p, prered=%x, expected %x\n",
281 hdr, hdr->prered, SMALLOC_PRE_RED);
282 assert(0);
283 }
284 if (*postred != SMALLOC_POST_RED) {
285 fprintf(stderr, "smalloc post redzone destroyed!\n");
286 fprintf(stderr, " ptr=%p, postred=%x, expected %x\n",
287 hdr, *postred, SMALLOC_POST_RED);
288 assert(0);
289 }
290 }
291 #else
fill_redzone(struct block_hdr * hdr)292 static void fill_redzone(struct block_hdr *hdr)
293 {
294 }
295
sfree_check_redzone(struct block_hdr * hdr)296 static void sfree_check_redzone(struct block_hdr *hdr)
297 {
298 }
299 #endif
300
sfree_pool(struct pool * pool,void * ptr)301 static void sfree_pool(struct pool *pool, void *ptr)
302 {
303 struct block_hdr *hdr;
304 unsigned int i, idx;
305 unsigned long offset;
306
307 if (!ptr)
308 return;
309
310 ptr -= sizeof(*hdr);
311 hdr = ptr;
312
313 assert(ptr_valid(pool, ptr));
314
315 sfree_check_redzone(hdr);
316
317 offset = ptr - pool->map;
318 i = offset / SMALLOC_BPL;
319 idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;
320
321 pool_lock(pool);
322 clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
323 if (i < pool->next_non_full)
324 pool->next_non_full = i;
325 pool->free_blocks += size_to_blocks(hdr->size);
326 pool_unlock(pool);
327 }
328
sfree(void * ptr)329 void sfree(void *ptr)
330 {
331 struct pool *pool = NULL;
332 unsigned int i;
333
334 if (!ptr)
335 return;
336
337 global_read_lock();
338
339 for (i = 0; i < nr_pools; i++) {
340 if (ptr_valid(&mp[i], ptr)) {
341 pool = &mp[i];
342 break;
343 }
344 }
345
346 global_read_unlock();
347
348 assert(pool);
349 sfree_pool(pool, ptr);
350 }
351
__smalloc_pool(struct pool * pool,size_t size)352 static void *__smalloc_pool(struct pool *pool, size_t size)
353 {
354 size_t nr_blocks;
355 unsigned int i;
356 unsigned int offset;
357 unsigned int last_idx;
358 void *ret = NULL;
359
360 pool_lock(pool);
361
362 nr_blocks = size_to_blocks(size);
363 if (nr_blocks > pool->free_blocks)
364 goto fail;
365
366 i = pool->next_non_full;
367 last_idx = 0;
368 offset = -1U;
369 while (i < pool->nr_blocks) {
370 unsigned int idx;
371
372 if (pool->bitmap[i] == -1U) {
373 i++;
374 pool->next_non_full = i;
375 last_idx = 0;
376 continue;
377 }
378
379 idx = find_next_zero(pool->bitmap[i], last_idx);
380 if (!blocks_free(pool, i, idx, nr_blocks)) {
381 idx += nr_blocks;
382 if (idx < SMALLOC_BPI)
383 last_idx = idx;
384 else {
385 last_idx = 0;
386 while (idx >= SMALLOC_BPI) {
387 i++;
388 idx -= SMALLOC_BPI;
389 }
390 }
391 continue;
392 }
393 set_blocks(pool, i, idx, nr_blocks);
394 offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
395 break;
396 }
397
398 if (i < pool->nr_blocks) {
399 pool->free_blocks -= nr_blocks;
400 ret = pool->map + offset;
401 }
402 fail:
403 pool_unlock(pool);
404 return ret;
405 }
406
smalloc_pool(struct pool * pool,size_t size)407 static void *smalloc_pool(struct pool *pool, size_t size)
408 {
409 size_t alloc_size = size + sizeof(struct block_hdr);
410 void *ptr;
411
412 /*
413 * Round to int alignment, so that the postred pointer will
414 * be naturally aligned as well.
415 */
416 #ifdef SMALLOC_REDZONE
417 alloc_size += sizeof(unsigned int);
418 alloc_size = (alloc_size + int_mask) & ~int_mask;
419 #endif
420
421 ptr = __smalloc_pool(pool, alloc_size);
422 if (ptr) {
423 struct block_hdr *hdr = ptr;
424
425 hdr->size = alloc_size;
426 fill_redzone(hdr);
427
428 ptr += sizeof(*hdr);
429 memset(ptr, 0, size);
430 }
431
432 return ptr;
433 }
434
smalloc(size_t size)435 void *smalloc(size_t size)
436 {
437 unsigned int i;
438
439 if (size != (unsigned int) size)
440 return NULL;
441
442 global_write_lock();
443 i = last_pool;
444
445 do {
446 for (; i < nr_pools; i++) {
447 void *ptr = smalloc_pool(&mp[i], size);
448
449 if (ptr) {
450 last_pool = i;
451 global_write_unlock();
452 return ptr;
453 }
454 }
455 if (last_pool) {
456 last_pool = 0;
457 continue;
458 }
459
460 if (nr_pools + 1 > MAX_POOLS)
461 break;
462 else {
463 i = nr_pools;
464 if (add_pool(&mp[nr_pools], size))
465 goto out;
466 }
467 } while (1);
468
469 out:
470 global_write_unlock();
471 return NULL;
472 }
473
smalloc_strdup(const char * str)474 char *smalloc_strdup(const char *str)
475 {
476 char *ptr;
477
478 ptr = smalloc(strlen(str) + 1);
479 strcpy(ptr, str);
480 return ptr;
481 }
482