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fa8d436c | 1 | /* Malloc implementation for multiple threads without lock contention. |
a784e502 | 2 | Copyright (C) 2001,2002,2003,2004,2005,2006,2007,2009,2010,2011,2012 |
c7fd3362 | 3 | Free Software Foundation, Inc. |
fa8d436c UD |
4 | This file is part of the GNU C Library. |
5 | Contributed by Wolfram Gloger <wg@malloc.de>, 2001. | |
6 | ||
7 | The GNU C Library is free software; you can redistribute it and/or | |
cc7375ce RM |
8 | modify it under the terms of the GNU Lesser General Public License as |
9 | published by the Free Software Foundation; either version 2.1 of the | |
fa8d436c UD |
10 | License, or (at your option) any later version. |
11 | ||
12 | The GNU C Library is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
cc7375ce | 15 | Lesser General Public License for more details. |
fa8d436c | 16 | |
cc7375ce | 17 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
18 | License along with the GNU C Library; see the file COPYING.LIB. If |
19 | not, see <http://www.gnu.org/licenses/>. */ | |
fa8d436c | 20 | |
a28b6b0a RM |
21 | #include <stdbool.h> |
22 | ||
fa8d436c UD |
23 | /* Compile-time constants. */ |
24 | ||
25 | #define HEAP_MIN_SIZE (32*1024) | |
26 | #ifndef HEAP_MAX_SIZE | |
e404fb16 | 27 | # ifdef DEFAULT_MMAP_THRESHOLD_MAX |
bd2c2341 | 28 | # define HEAP_MAX_SIZE (2 * DEFAULT_MMAP_THRESHOLD_MAX) |
e404fb16 UD |
29 | # else |
30 | # define HEAP_MAX_SIZE (1024*1024) /* must be a power of two */ | |
31 | # endif | |
fa8d436c UD |
32 | #endif |
33 | ||
34 | /* HEAP_MIN_SIZE and HEAP_MAX_SIZE limit the size of mmap()ed heaps | |
35 | that are dynamically created for multi-threaded programs. The | |
36 | maximum size must be a power of two, for fast determination of | |
37 | which heap belongs to a chunk. It should be much larger than the | |
38 | mmap threshold, so that requests with a size just below that | |
39 | threshold can be fulfilled without creating too many heaps. */ | |
40 | ||
41 | ||
42 | #ifndef THREAD_STATS | |
43 | #define THREAD_STATS 0 | |
44 | #endif | |
45 | ||
46 | /* If THREAD_STATS is non-zero, some statistics on mutex locking are | |
47 | computed. */ | |
48 | ||
49 | /***************************************************************************/ | |
50 | ||
51 | #define top(ar_ptr) ((ar_ptr)->top) | |
52 | ||
53 | /* A heap is a single contiguous memory region holding (coalesceable) | |
54 | malloc_chunks. It is allocated with mmap() and always starts at an | |
22a89187 | 55 | address aligned to HEAP_MAX_SIZE. */ |
fa8d436c UD |
56 | |
57 | typedef struct _heap_info { | |
58 | mstate ar_ptr; /* Arena for this heap. */ | |
59 | struct _heap_info *prev; /* Previous heap. */ | |
60 | size_t size; /* Current size in bytes. */ | |
c7fd3362 JJ |
61 | size_t mprotect_size; /* Size in bytes that has been mprotected |
62 | PROT_READ|PROT_WRITE. */ | |
7d013a64 RM |
63 | /* Make sure the following data is properly aligned, particularly |
64 | that sizeof (heap_info) + 2 * SIZE_SZ is a multiple of | |
c7fd3362 JJ |
65 | MALLOC_ALIGNMENT. */ |
66 | char pad[-6 * SIZE_SZ & MALLOC_ALIGN_MASK]; | |
fa8d436c UD |
67 | } heap_info; |
68 | ||
7d013a64 RM |
69 | /* Get a compile-time error if the heap_info padding is not correct |
70 | to make alignment work as expected in sYSMALLOc. */ | |
71 | extern int sanity_check_heap_info_alignment[(sizeof (heap_info) | |
72 | + 2 * SIZE_SZ) % MALLOC_ALIGNMENT | |
73 | ? -1 : 1]; | |
74 | ||
fa8d436c UD |
75 | /* Thread specific data */ |
76 | ||
77 | static tsd_key_t arena_key; | |
02d46fc4 | 78 | static mutex_t list_lock = MUTEX_INITIALIZER; |
425ce2ed | 79 | #ifdef PER_THREAD |
02d46fc4 | 80 | static size_t narenas = 1; |
425ce2ed UD |
81 | static mstate free_list; |
82 | #endif | |
fa8d436c UD |
83 | |
84 | #if THREAD_STATS | |
85 | static int stat_n_heaps; | |
86 | #define THREAD_STAT(x) x | |
87 | #else | |
88 | #define THREAD_STAT(x) do ; while(0) | |
89 | #endif | |
90 | ||
91 | /* Mapped memory in non-main arenas (reliable only for NO_THREADS). */ | |
92 | static unsigned long arena_mem; | |
93 | ||
2a652f5a RM |
94 | /* Already initialized? */ |
95 | int __malloc_initialized = -1; | |
96 | ||
fa8d436c UD |
97 | /**************************************************************************/ |
98 | ||
fa8d436c UD |
99 | |
100 | /* arena_get() acquires an arena and locks the corresponding mutex. | |
101 | First, try the one last locked successfully by this thread. (This | |
102 | is the common case and handled with a macro for speed.) Then, loop | |
103 | once over the circularly linked list of arenas. If no arena is | |
104 | readily available, create a new one. In this latter case, `size' | |
105 | is just a hint as to how much memory will be required immediately | |
106 | in the new arena. */ | |
107 | ||
108 | #define arena_get(ptr, size) do { \ | |
425ce2ed UD |
109 | arena_lookup(ptr); \ |
110 | arena_lock(ptr, size); \ | |
111 | } while(0) | |
112 | ||
113 | #define arena_lookup(ptr) do { \ | |
22a89187 | 114 | void *vptr = NULL; \ |
fa8d436c | 115 | ptr = (mstate)tsd_getspecific(arena_key, vptr); \ |
425ce2ed UD |
116 | } while(0) |
117 | ||
118 | #ifdef PER_THREAD | |
22a89187 | 119 | # define arena_lock(ptr, size) do { \ |
425ce2ed UD |
120 | if(ptr) \ |
121 | (void)mutex_lock(&ptr->mutex); \ | |
122 | else \ | |
bf51f568 | 123 | ptr = arena_get2(ptr, (size), NULL); \ |
425ce2ed UD |
124 | } while(0) |
125 | #else | |
22a89187 | 126 | # define arena_lock(ptr, size) do { \ |
fa8d436c UD |
127 | if(ptr && !mutex_trylock(&ptr->mutex)) { \ |
128 | THREAD_STAT(++(ptr->stat_lock_direct)); \ | |
129 | } else \ | |
bf51f568 | 130 | ptr = arena_get2(ptr, (size), NULL); \ |
fa8d436c | 131 | } while(0) |
425ce2ed | 132 | #endif |
fa8d436c UD |
133 | |
134 | /* find the heap and corresponding arena for a given ptr */ | |
135 | ||
136 | #define heap_for_ptr(ptr) \ | |
137 | ((heap_info *)((unsigned long)(ptr) & ~(HEAP_MAX_SIZE-1))) | |
138 | #define arena_for_chunk(ptr) \ | |
139 | (chunk_non_main_arena(ptr) ? heap_for_ptr(ptr)->ar_ptr : &main_arena) | |
140 | ||
fa8d436c UD |
141 | |
142 | /**************************************************************************/ | |
143 | ||
fa8d436c UD |
144 | /* atfork support. */ |
145 | ||
06d6611a | 146 | static __malloc_ptr_t (*save_malloc_hook) (size_t __size, |
a784e502 | 147 | const __malloc_ptr_t); |
06d6611a | 148 | static void (*save_free_hook) (__malloc_ptr_t __ptr, |
a784e502 | 149 | const __malloc_ptr_t); |
22a89187 | 150 | static void* save_arena; |
fa8d436c | 151 | |
666aa020 UD |
152 | #ifdef ATFORK_MEM |
153 | ATFORK_MEM; | |
154 | #endif | |
155 | ||
fa8d436c UD |
156 | /* Magic value for the thread-specific arena pointer when |
157 | malloc_atfork() is in use. */ | |
158 | ||
22a89187 | 159 | #define ATFORK_ARENA_PTR ((void*)-1) |
fa8d436c UD |
160 | |
161 | /* The following hooks are used while the `atfork' handling mechanism | |
162 | is active. */ | |
163 | ||
22a89187 UD |
164 | static void* |
165 | malloc_atfork(size_t sz, const void *caller) | |
fa8d436c | 166 | { |
22a89187 UD |
167 | void *vptr = NULL; |
168 | void *victim; | |
fa8d436c UD |
169 | |
170 | tsd_getspecific(arena_key, vptr); | |
171 | if(vptr == ATFORK_ARENA_PTR) { | |
172 | /* We are the only thread that may allocate at all. */ | |
173 | if(save_malloc_hook != malloc_check) { | |
174 | return _int_malloc(&main_arena, sz); | |
175 | } else { | |
176 | if(top_check()<0) | |
b9b42ee0 | 177 | return 0; |
fa8d436c UD |
178 | victim = _int_malloc(&main_arena, sz+1); |
179 | return mem2mem_check(victim, sz); | |
180 | } | |
181 | } else { | |
182 | /* Suspend the thread until the `atfork' handlers have completed. | |
183 | By that time, the hooks will have been reset as well, so that | |
184 | mALLOc() can be used again. */ | |
185 | (void)mutex_lock(&list_lock); | |
186 | (void)mutex_unlock(&list_lock); | |
3b49edc0 | 187 | return __libc_malloc(sz); |
fa8d436c UD |
188 | } |
189 | } | |
190 | ||
191 | static void | |
22a89187 | 192 | free_atfork(void* mem, const void *caller) |
fa8d436c | 193 | { |
22a89187 | 194 | void *vptr = NULL; |
fa8d436c UD |
195 | mstate ar_ptr; |
196 | mchunkptr p; /* chunk corresponding to mem */ | |
197 | ||
198 | if (mem == 0) /* free(0) has no effect */ | |
199 | return; | |
200 | ||
201 | p = mem2chunk(mem); /* do not bother to replicate free_check here */ | |
202 | ||
fa8d436c UD |
203 | if (chunk_is_mmapped(p)) /* release mmapped memory. */ |
204 | { | |
205 | munmap_chunk(p); | |
206 | return; | |
207 | } | |
fa8d436c | 208 | |
425ce2ed UD |
209 | ar_ptr = arena_for_chunk(p); |
210 | tsd_getspecific(arena_key, vptr); | |
211 | _int_free(ar_ptr, p, vptr == ATFORK_ARENA_PTR); | |
fa8d436c UD |
212 | } |
213 | ||
7dac9f3d UD |
214 | |
215 | /* Counter for number of times the list is locked by the same thread. */ | |
216 | static unsigned int atfork_recursive_cntr; | |
217 | ||
fa8d436c UD |
218 | /* The following two functions are registered via thread_atfork() to |
219 | make sure that the mutexes remain in a consistent state in the | |
220 | fork()ed version of a thread. Also adapt the malloc and free hooks | |
221 | temporarily, because the `atfork' handler mechanism may use | |
222 | malloc/free internally (e.g. in LinuxThreads). */ | |
223 | ||
224 | static void | |
06d6611a | 225 | ptmalloc_lock_all (void) |
fa8d436c UD |
226 | { |
227 | mstate ar_ptr; | |
228 | ||
2a652f5a RM |
229 | if(__malloc_initialized < 1) |
230 | return; | |
7dac9f3d UD |
231 | if (mutex_trylock(&list_lock)) |
232 | { | |
22a89187 | 233 | void *my_arena; |
7dac9f3d UD |
234 | tsd_getspecific(arena_key, my_arena); |
235 | if (my_arena == ATFORK_ARENA_PTR) | |
236 | /* This is the same thread which already locks the global list. | |
237 | Just bump the counter. */ | |
238 | goto out; | |
239 | ||
240 | /* This thread has to wait its turn. */ | |
241 | (void)mutex_lock(&list_lock); | |
242 | } | |
fa8d436c UD |
243 | for(ar_ptr = &main_arena;;) { |
244 | (void)mutex_lock(&ar_ptr->mutex); | |
245 | ar_ptr = ar_ptr->next; | |
246 | if(ar_ptr == &main_arena) break; | |
247 | } | |
248 | save_malloc_hook = __malloc_hook; | |
249 | save_free_hook = __free_hook; | |
250 | __malloc_hook = malloc_atfork; | |
251 | __free_hook = free_atfork; | |
252 | /* Only the current thread may perform malloc/free calls now. */ | |
253 | tsd_getspecific(arena_key, save_arena); | |
254 | tsd_setspecific(arena_key, ATFORK_ARENA_PTR); | |
7dac9f3d UD |
255 | out: |
256 | ++atfork_recursive_cntr; | |
fa8d436c UD |
257 | } |
258 | ||
259 | static void | |
06d6611a | 260 | ptmalloc_unlock_all (void) |
fa8d436c UD |
261 | { |
262 | mstate ar_ptr; | |
263 | ||
2a652f5a RM |
264 | if(__malloc_initialized < 1) |
265 | return; | |
7dac9f3d UD |
266 | if (--atfork_recursive_cntr != 0) |
267 | return; | |
fa8d436c UD |
268 | tsd_setspecific(arena_key, save_arena); |
269 | __malloc_hook = save_malloc_hook; | |
270 | __free_hook = save_free_hook; | |
271 | for(ar_ptr = &main_arena;;) { | |
272 | (void)mutex_unlock(&ar_ptr->mutex); | |
273 | ar_ptr = ar_ptr->next; | |
274 | if(ar_ptr == &main_arena) break; | |
275 | } | |
276 | (void)mutex_unlock(&list_lock); | |
277 | } | |
278 | ||
279 | #ifdef __linux__ | |
280 | ||
e851dca1 | 281 | /* In NPTL, unlocking a mutex in the child process after a |
fa8d436c UD |
282 | fork() is currently unsafe, whereas re-initializing it is safe and |
283 | does not leak resources. Therefore, a special atfork handler is | |
284 | installed for the child. */ | |
285 | ||
286 | static void | |
06d6611a | 287 | ptmalloc_unlock_all2 (void) |
fa8d436c UD |
288 | { |
289 | mstate ar_ptr; | |
290 | ||
2a652f5a RM |
291 | if(__malloc_initialized < 1) |
292 | return; | |
fa8d436c UD |
293 | tsd_setspecific(arena_key, save_arena); |
294 | __malloc_hook = save_malloc_hook; | |
295 | __free_hook = save_free_hook; | |
425ce2ed UD |
296 | #ifdef PER_THREAD |
297 | free_list = NULL; | |
fa8d436c UD |
298 | #endif |
299 | for(ar_ptr = &main_arena;;) { | |
fdb933e2 | 300 | mutex_init(&ar_ptr->mutex); |
425ce2ed UD |
301 | #ifdef PER_THREAD |
302 | if (ar_ptr != save_arena) { | |
303 | ar_ptr->next_free = free_list; | |
304 | free_list = ar_ptr; | |
305 | } | |
306 | #endif | |
fa8d436c UD |
307 | ar_ptr = ar_ptr->next; |
308 | if(ar_ptr == &main_arena) break; | |
309 | } | |
fdb933e2 | 310 | mutex_init(&list_lock); |
e851dca1 | 311 | atfork_recursive_cntr = 0; |
fa8d436c UD |
312 | } |
313 | ||
314 | #else | |
315 | ||
316 | #define ptmalloc_unlock_all2 ptmalloc_unlock_all | |
317 | ||
318 | #endif | |
319 | ||
fa8d436c | 320 | /* Initialization routine. */ |
fa8d436c UD |
321 | #include <string.h> |
322 | extern char **_environ; | |
323 | ||
324 | static char * | |
325 | internal_function | |
326 | next_env_entry (char ***position) | |
327 | { | |
328 | char **current = *position; | |
329 | char *result = NULL; | |
330 | ||
331 | while (*current != NULL) | |
332 | { | |
333 | if (__builtin_expect ((*current)[0] == 'M', 0) | |
334 | && (*current)[1] == 'A' | |
335 | && (*current)[2] == 'L' | |
336 | && (*current)[3] == 'L' | |
337 | && (*current)[4] == 'O' | |
338 | && (*current)[5] == 'C' | |
339 | && (*current)[6] == '_') | |
340 | { | |
341 | result = &(*current)[7]; | |
342 | ||
343 | /* Save current position for next visit. */ | |
344 | *position = ++current; | |
345 | ||
346 | break; | |
347 | } | |
348 | ||
349 | ++current; | |
350 | } | |
351 | ||
352 | return result; | |
353 | } | |
fa8d436c | 354 | |
c0f62c56 | 355 | |
22a89187 | 356 | #ifdef SHARED |
c0f62c56 UD |
357 | static void * |
358 | __failing_morecore (ptrdiff_t d) | |
359 | { | |
360 | return (void *) MORECORE_FAILURE; | |
361 | } | |
5f21997b UD |
362 | |
363 | extern struct dl_open_hook *_dl_open_hook; | |
364 | libc_hidden_proto (_dl_open_hook); | |
fde89ad0 RM |
365 | #endif |
366 | ||
fa8d436c | 367 | static void |
06d6611a | 368 | ptmalloc_init (void) |
fa8d436c | 369 | { |
fa8d436c UD |
370 | if(__malloc_initialized >= 0) return; |
371 | __malloc_initialized = 0; | |
372 | ||
22a89187 | 373 | #ifdef SHARED |
5f21997b UD |
374 | /* In case this libc copy is in a non-default namespace, never use brk. |
375 | Likewise if dlopened from statically linked program. */ | |
c0f62c56 UD |
376 | Dl_info di; |
377 | struct link_map *l; | |
5f21997b UD |
378 | |
379 | if (_dl_open_hook != NULL | |
380 | || (_dl_addr (ptmalloc_init, &di, &l, NULL) != 0 | |
381 | && l->l_ns != LM_ID_BASE)) | |
c0f62c56 UD |
382 | __morecore = __failing_morecore; |
383 | #endif | |
384 | ||
fa8d436c | 385 | tsd_key_create(&arena_key, NULL); |
22a89187 | 386 | tsd_setspecific(arena_key, (void *)&main_arena); |
fa8d436c | 387 | thread_atfork(ptmalloc_lock_all, ptmalloc_unlock_all, ptmalloc_unlock_all2); |
02d46fc4 | 388 | const char *s = NULL; |
08e49216 RM |
389 | if (__builtin_expect (_environ != NULL, 1)) |
390 | { | |
391 | char **runp = _environ; | |
392 | char *envline; | |
393 | ||
394 | while (__builtin_expect ((envline = next_env_entry (&runp)) != NULL, | |
395 | 0)) | |
396 | { | |
397 | size_t len = strcspn (envline, "="); | |
398 | ||
399 | if (envline[len] != '=') | |
400 | /* This is a "MALLOC_" variable at the end of the string | |
401 | without a '=' character. Ignore it since otherwise we | |
402 | will access invalid memory below. */ | |
403 | continue; | |
404 | ||
405 | switch (len) | |
406 | { | |
407 | case 6: | |
408 | if (memcmp (envline, "CHECK_", 6) == 0) | |
409 | s = &envline[7]; | |
410 | break; | |
411 | case 8: | |
02d46fc4 | 412 | if (! __builtin_expect (__libc_enable_secure, 0)) |
a5a33449 UD |
413 | { |
414 | if (memcmp (envline, "TOP_PAD_", 8) == 0) | |
3b49edc0 | 415 | __libc_mallopt(M_TOP_PAD, atoi(&envline[9])); |
a5a33449 | 416 | else if (memcmp (envline, "PERTURB_", 8) == 0) |
3b49edc0 | 417 | __libc_mallopt(M_PERTURB, atoi(&envline[9])); |
a5a33449 | 418 | } |
08e49216 RM |
419 | break; |
420 | case 9: | |
02d46fc4 | 421 | if (! __builtin_expect (__libc_enable_secure, 0)) |
425ce2ed UD |
422 | { |
423 | if (memcmp (envline, "MMAP_MAX_", 9) == 0) | |
3b49edc0 | 424 | __libc_mallopt(M_MMAP_MAX, atoi(&envline[10])); |
425ce2ed UD |
425 | #ifdef PER_THREAD |
426 | else if (memcmp (envline, "ARENA_MAX", 9) == 0) | |
3b49edc0 | 427 | __libc_mallopt(M_ARENA_MAX, atoi(&envline[10])); |
425ce2ed UD |
428 | #endif |
429 | } | |
08e49216 | 430 | break; |
425ce2ed UD |
431 | #ifdef PER_THREAD |
432 | case 10: | |
02d46fc4 | 433 | if (! __builtin_expect (__libc_enable_secure, 0)) |
425ce2ed UD |
434 | { |
435 | if (memcmp (envline, "ARENA_TEST", 10) == 0) | |
3b49edc0 | 436 | __libc_mallopt(M_ARENA_TEST, atoi(&envline[11])); |
425ce2ed UD |
437 | } |
438 | break; | |
439 | #endif | |
08e49216 | 440 | case 15: |
02d46fc4 | 441 | if (! __builtin_expect (__libc_enable_secure, 0)) |
08e49216 RM |
442 | { |
443 | if (memcmp (envline, "TRIM_THRESHOLD_", 15) == 0) | |
3b49edc0 | 444 | __libc_mallopt(M_TRIM_THRESHOLD, atoi(&envline[16])); |
08e49216 | 445 | else if (memcmp (envline, "MMAP_THRESHOLD_", 15) == 0) |
3b49edc0 | 446 | __libc_mallopt(M_MMAP_THRESHOLD, atoi(&envline[16])); |
08e49216 RM |
447 | } |
448 | break; | |
449 | default: | |
450 | break; | |
451 | } | |
452 | } | |
453 | } | |
ceba6be7 | 454 | if(s && s[0]) { |
3b49edc0 | 455 | __libc_mallopt(M_CHECK_ACTION, (int)(s[0] - '0')); |
a19fe332 UD |
456 | if (check_action != 0) |
457 | __malloc_check_init(); | |
fa8d436c | 458 | } |
df77455c UD |
459 | void (*hook) (void) = force_reg (__malloc_initialize_hook); |
460 | if (hook != NULL) | |
461 | (*hook)(); | |
fa8d436c UD |
462 | __malloc_initialized = 1; |
463 | } | |
464 | ||
465 | /* There are platforms (e.g. Hurd) with a link-time hook mechanism. */ | |
466 | #ifdef thread_atfork_static | |
467 | thread_atfork_static(ptmalloc_lock_all, ptmalloc_unlock_all, \ | |
b9b42ee0 | 468 | ptmalloc_unlock_all2) |
fa8d436c UD |
469 | #endif |
470 | ||
471 | \f | |
472 | ||
473 | /* Managing heaps and arenas (for concurrent threads) */ | |
474 | ||
fa8d436c UD |
475 | #if MALLOC_DEBUG > 1 |
476 | ||
477 | /* Print the complete contents of a single heap to stderr. */ | |
478 | ||
479 | static void | |
fa8d436c | 480 | dump_heap(heap_info *heap) |
fa8d436c UD |
481 | { |
482 | char *ptr; | |
483 | mchunkptr p; | |
484 | ||
485 | fprintf(stderr, "Heap %p, size %10lx:\n", heap, (long)heap->size); | |
486 | ptr = (heap->ar_ptr != (mstate)(heap+1)) ? | |
487 | (char*)(heap + 1) : (char*)(heap + 1) + sizeof(struct malloc_state); | |
488 | p = (mchunkptr)(((unsigned long)ptr + MALLOC_ALIGN_MASK) & | |
b9b42ee0 | 489 | ~MALLOC_ALIGN_MASK); |
fa8d436c UD |
490 | for(;;) { |
491 | fprintf(stderr, "chunk %p size %10lx", p, (long)p->size); | |
492 | if(p == top(heap->ar_ptr)) { | |
493 | fprintf(stderr, " (top)\n"); | |
494 | break; | |
495 | } else if(p->size == (0|PREV_INUSE)) { | |
496 | fprintf(stderr, " (fence)\n"); | |
497 | break; | |
498 | } | |
499 | fprintf(stderr, "\n"); | |
500 | p = next_chunk(p); | |
501 | } | |
502 | } | |
503 | ||
504 | #endif /* MALLOC_DEBUG > 1 */ | |
505 | ||
26d550d3 UD |
506 | /* If consecutive mmap (0, HEAP_MAX_SIZE << 1, ...) calls return decreasing |
507 | addresses as opposed to increasing, new_heap would badly fragment the | |
508 | address space. In that case remember the second HEAP_MAX_SIZE part | |
509 | aligned to HEAP_MAX_SIZE from last mmap (0, HEAP_MAX_SIZE << 1, ...) | |
510 | call (if it is already aligned) and try to reuse it next time. We need | |
511 | no locking for it, as kernel ensures the atomicity for us - worst case | |
512 | we'll call mmap (addr, HEAP_MAX_SIZE, ...) for some value of addr in | |
513 | multiple threads, but only one will succeed. */ | |
514 | static char *aligned_heap_area; | |
515 | ||
fa8d436c UD |
516 | /* Create a new heap. size is automatically rounded up to a multiple |
517 | of the page size. */ | |
518 | ||
519 | static heap_info * | |
520 | internal_function | |
fa8d436c | 521 | new_heap(size_t size, size_t top_pad) |
fa8d436c | 522 | { |
02d46fc4 | 523 | size_t page_mask = GLRO(dl_pagesize) - 1; |
fa8d436c UD |
524 | char *p1, *p2; |
525 | unsigned long ul; | |
526 | heap_info *h; | |
527 | ||
528 | if(size+top_pad < HEAP_MIN_SIZE) | |
529 | size = HEAP_MIN_SIZE; | |
530 | else if(size+top_pad <= HEAP_MAX_SIZE) | |
531 | size += top_pad; | |
532 | else if(size > HEAP_MAX_SIZE) | |
533 | return 0; | |
534 | else | |
535 | size = HEAP_MAX_SIZE; | |
536 | size = (size + page_mask) & ~page_mask; | |
537 | ||
538 | /* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed. | |
539 | No swap space needs to be reserved for the following large | |
540 | mapping (on Linux, this is the case for all non-writable mappings | |
541 | anyway). */ | |
26d550d3 UD |
542 | p2 = MAP_FAILED; |
543 | if(aligned_heap_area) { | |
544 | p2 = (char *)MMAP(aligned_heap_area, HEAP_MAX_SIZE, PROT_NONE, | |
3b49edc0 | 545 | MAP_NORESERVE); |
26d550d3 UD |
546 | aligned_heap_area = NULL; |
547 | if (p2 != MAP_FAILED && ((unsigned long)p2 & (HEAP_MAX_SIZE-1))) { | |
3b49edc0 | 548 | __munmap(p2, HEAP_MAX_SIZE); |
26d550d3 UD |
549 | p2 = MAP_FAILED; |
550 | } | |
551 | } | |
552 | if(p2 == MAP_FAILED) { | |
3b49edc0 | 553 | p1 = (char *)MMAP(0, HEAP_MAX_SIZE<<1, PROT_NONE, MAP_NORESERVE); |
26d550d3 UD |
554 | if(p1 != MAP_FAILED) { |
555 | p2 = (char *)(((unsigned long)p1 + (HEAP_MAX_SIZE-1)) | |
556 | & ~(HEAP_MAX_SIZE-1)); | |
557 | ul = p2 - p1; | |
558 | if (ul) | |
3b49edc0 | 559 | __munmap(p1, ul); |
26d550d3 UD |
560 | else |
561 | aligned_heap_area = p2 + HEAP_MAX_SIZE; | |
3b49edc0 | 562 | __munmap(p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul); |
26d550d3 UD |
563 | } else { |
564 | /* Try to take the chance that an allocation of only HEAP_MAX_SIZE | |
565 | is already aligned. */ | |
3b49edc0 | 566 | p2 = (char *)MMAP(0, HEAP_MAX_SIZE, PROT_NONE, MAP_NORESERVE); |
26d550d3 UD |
567 | if(p2 == MAP_FAILED) |
568 | return 0; | |
569 | if((unsigned long)p2 & (HEAP_MAX_SIZE-1)) { | |
3b49edc0 | 570 | __munmap(p2, HEAP_MAX_SIZE); |
26d550d3 UD |
571 | return 0; |
572 | } | |
fa8d436c UD |
573 | } |
574 | } | |
3b49edc0 UD |
575 | if(__mprotect(p2, size, PROT_READ|PROT_WRITE) != 0) { |
576 | __munmap(p2, HEAP_MAX_SIZE); | |
fa8d436c UD |
577 | return 0; |
578 | } | |
579 | h = (heap_info *)p2; | |
580 | h->size = size; | |
c7fd3362 | 581 | h->mprotect_size = size; |
fa8d436c UD |
582 | THREAD_STAT(stat_n_heaps++); |
583 | return h; | |
584 | } | |
585 | ||
cbf5760e UD |
586 | /* Grow a heap. size is automatically rounded up to a |
587 | multiple of the page size. */ | |
fa8d436c UD |
588 | |
589 | static int | |
fa8d436c | 590 | grow_heap(heap_info *h, long diff) |
fa8d436c | 591 | { |
02d46fc4 | 592 | size_t page_mask = GLRO(dl_pagesize) - 1; |
fa8d436c UD |
593 | long new_size; |
594 | ||
cbf5760e UD |
595 | diff = (diff + page_mask) & ~page_mask; |
596 | new_size = (long)h->size + diff; | |
597 | if((unsigned long) new_size > (unsigned long) HEAP_MAX_SIZE) | |
598 | return -1; | |
599 | if((unsigned long) new_size > h->mprotect_size) { | |
3b49edc0 UD |
600 | if (__mprotect((char *)h + h->mprotect_size, |
601 | (unsigned long) new_size - h->mprotect_size, | |
602 | PROT_READ|PROT_WRITE) != 0) | |
cbf5760e UD |
603 | return -2; |
604 | h->mprotect_size = new_size; | |
605 | } | |
606 | ||
607 | h->size = new_size; | |
608 | return 0; | |
609 | } | |
610 | ||
611 | /* Shrink a heap. */ | |
612 | ||
613 | static int | |
cbf5760e | 614 | shrink_heap(heap_info *h, long diff) |
cbf5760e UD |
615 | { |
616 | long new_size; | |
617 | ||
618 | new_size = (long)h->size - diff; | |
619 | if(new_size < (long)sizeof(*h)) | |
620 | return -1; | |
621 | /* Try to re-map the extra heap space freshly to save memory, and | |
622 | make it inaccessible. */ | |
cbf5760e | 623 | if (__builtin_expect (__libc_enable_secure, 0)) |
cbf5760e UD |
624 | { |
625 | if((char *)MMAP((char *)h + new_size, diff, PROT_NONE, | |
3b49edc0 | 626 | MAP_FIXED) == (char *) MAP_FAILED) |
cbf5760e UD |
627 | return -2; |
628 | h->mprotect_size = new_size; | |
629 | } | |
cbf5760e UD |
630 | else |
631 | madvise ((char *)h + new_size, diff, MADV_DONTNEED); | |
cbf5760e UD |
632 | /*fprintf(stderr, "shrink %p %08lx\n", h, new_size);*/ |
633 | ||
fa8d436c UD |
634 | h->size = new_size; |
635 | return 0; | |
636 | } | |
637 | ||
638 | /* Delete a heap. */ | |
639 | ||
26d550d3 UD |
640 | #define delete_heap(heap) \ |
641 | do { \ | |
642 | if ((char *)(heap) + HEAP_MAX_SIZE == aligned_heap_area) \ | |
643 | aligned_heap_area = NULL; \ | |
3b49edc0 | 644 | __munmap((char*)(heap), HEAP_MAX_SIZE); \ |
26d550d3 | 645 | } while (0) |
fa8d436c UD |
646 | |
647 | static int | |
648 | internal_function | |
fa8d436c | 649 | heap_trim(heap_info *heap, size_t pad) |
fa8d436c UD |
650 | { |
651 | mstate ar_ptr = heap->ar_ptr; | |
02d46fc4 | 652 | unsigned long pagesz = GLRO(dl_pagesize); |
fa8d436c UD |
653 | mchunkptr top_chunk = top(ar_ptr), p, bck, fwd; |
654 | heap_info *prev_heap; | |
655 | long new_size, top_size, extra; | |
656 | ||
657 | /* Can this heap go away completely? */ | |
658 | while(top_chunk == chunk_at_offset(heap, sizeof(*heap))) { | |
659 | prev_heap = heap->prev; | |
660 | p = chunk_at_offset(prev_heap, prev_heap->size - (MINSIZE-2*SIZE_SZ)); | |
661 | assert(p->size == (0|PREV_INUSE)); /* must be fencepost */ | |
662 | p = prev_chunk(p); | |
663 | new_size = chunksize(p) + (MINSIZE-2*SIZE_SZ); | |
664 | assert(new_size>0 && new_size<(long)(2*MINSIZE)); | |
665 | if(!prev_inuse(p)) | |
666 | new_size += p->prev_size; | |
667 | assert(new_size>0 && new_size<HEAP_MAX_SIZE); | |
668 | if(new_size + (HEAP_MAX_SIZE - prev_heap->size) < pad + MINSIZE + pagesz) | |
669 | break; | |
670 | ar_ptr->system_mem -= heap->size; | |
671 | arena_mem -= heap->size; | |
672 | delete_heap(heap); | |
673 | heap = prev_heap; | |
674 | if(!prev_inuse(p)) { /* consolidate backward */ | |
675 | p = prev_chunk(p); | |
676 | unlink(p, bck, fwd); | |
677 | } | |
678 | assert(((unsigned long)((char*)p + new_size) & (pagesz-1)) == 0); | |
679 | assert( ((char*)p + new_size) == ((char*)heap + heap->size) ); | |
680 | top(ar_ptr) = top_chunk = p; | |
681 | set_head(top_chunk, new_size | PREV_INUSE); | |
682 | /*check_chunk(ar_ptr, top_chunk);*/ | |
683 | } | |
684 | top_size = chunksize(top_chunk); | |
b9b42ee0 | 685 | extra = (top_size - pad - MINSIZE - 1) & ~(pagesz - 1); |
fa8d436c UD |
686 | if(extra < (long)pagesz) |
687 | return 0; | |
688 | /* Try to shrink. */ | |
cbf5760e | 689 | if(shrink_heap(heap, extra) != 0) |
fa8d436c UD |
690 | return 0; |
691 | ar_ptr->system_mem -= extra; | |
692 | arena_mem -= extra; | |
693 | ||
694 | /* Success. Adjust top accordingly. */ | |
695 | set_head(top_chunk, (top_size - extra) | PREV_INUSE); | |
696 | /*check_chunk(ar_ptr, top_chunk);*/ | |
697 | return 1; | |
698 | } | |
699 | ||
04ec80e4 UD |
700 | /* Create a new arena with initial size "size". */ |
701 | ||
702 | static mstate | |
703 | _int_new_arena(size_t size) | |
704 | { | |
705 | mstate a; | |
706 | heap_info *h; | |
707 | char *ptr; | |
708 | unsigned long misalign; | |
709 | ||
710 | h = new_heap(size + (sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT), | |
711 | mp_.top_pad); | |
712 | if(!h) { | |
713 | /* Maybe size is too large to fit in a single heap. So, just try | |
714 | to create a minimally-sized arena and let _int_malloc() attempt | |
715 | to deal with the large request via mmap_chunk(). */ | |
716 | h = new_heap(sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT, mp_.top_pad); | |
717 | if(!h) | |
718 | return 0; | |
719 | } | |
720 | a = h->ar_ptr = (mstate)(h+1); | |
721 | malloc_init_state(a); | |
722 | /*a->next = NULL;*/ | |
723 | a->system_mem = a->max_system_mem = h->size; | |
724 | arena_mem += h->size; | |
04ec80e4 UD |
725 | |
726 | /* Set up the top chunk, with proper alignment. */ | |
727 | ptr = (char *)(a + 1); | |
728 | misalign = (unsigned long)chunk2mem(ptr) & MALLOC_ALIGN_MASK; | |
729 | if (misalign > 0) | |
730 | ptr += MALLOC_ALIGNMENT - misalign; | |
731 | top(a) = (mchunkptr)ptr; | |
732 | set_head(top(a), (((char*)h + h->size) - ptr) | PREV_INUSE); | |
733 | ||
22a89187 | 734 | tsd_setspecific(arena_key, (void *)a); |
425ce2ed UD |
735 | mutex_init(&a->mutex); |
736 | (void)mutex_lock(&a->mutex); | |
737 | ||
738 | #ifdef PER_THREAD | |
739 | (void)mutex_lock(&list_lock); | |
740 | #endif | |
741 | ||
742 | /* Add the new arena to the global list. */ | |
743 | a->next = main_arena.next; | |
744 | atomic_write_barrier (); | |
745 | main_arena.next = a; | |
746 | ||
747 | #ifdef PER_THREAD | |
425ce2ed UD |
748 | (void)mutex_unlock(&list_lock); |
749 | #endif | |
750 | ||
751 | THREAD_STAT(++(a->stat_lock_loop)); | |
752 | ||
04ec80e4 UD |
753 | return a; |
754 | } | |
755 | ||
425ce2ed UD |
756 | |
757 | #ifdef PER_THREAD | |
758 | static mstate | |
759 | get_free_list (void) | |
760 | { | |
761 | mstate result = free_list; | |
762 | if (result != NULL) | |
763 | { | |
764 | (void)mutex_lock(&list_lock); | |
765 | result = free_list; | |
766 | if (result != NULL) | |
767 | free_list = result->next_free; | |
768 | (void)mutex_unlock(&list_lock); | |
769 | ||
770 | if (result != NULL) | |
771 | { | |
772 | (void)mutex_lock(&result->mutex); | |
22a89187 | 773 | tsd_setspecific(arena_key, (void *)result); |
425ce2ed UD |
774 | THREAD_STAT(++(result->stat_lock_loop)); |
775 | } | |
776 | } | |
777 | ||
778 | return result; | |
779 | } | |
780 | ||
bf51f568 JL |
781 | /* Lock and return an arena that can be reused for memory allocation. |
782 | Avoid AVOID_ARENA as we have already failed to allocate memory in | |
783 | it and it is currently locked. */ | |
425ce2ed | 784 | static mstate |
bf51f568 | 785 | reused_arena (mstate avoid_arena) |
425ce2ed | 786 | { |
425ce2ed UD |
787 | mstate result; |
788 | static mstate next_to_use; | |
789 | if (next_to_use == NULL) | |
790 | next_to_use = &main_arena; | |
791 | ||
792 | result = next_to_use; | |
793 | do | |
794 | { | |
795 | if (!mutex_trylock(&result->mutex)) | |
796 | goto out; | |
797 | ||
798 | result = result->next; | |
799 | } | |
800 | while (result != next_to_use); | |
801 | ||
bf51f568 JL |
802 | /* Avoid AVOID_ARENA as we have already failed to allocate memory |
803 | in that arena and it is currently locked. */ | |
804 | if (result == avoid_arena) | |
805 | result = result->next; | |
806 | ||
425ce2ed UD |
807 | /* No arena available. Wait for the next in line. */ |
808 | (void)mutex_lock(&result->mutex); | |
809 | ||
810 | out: | |
22a89187 | 811 | tsd_setspecific(arena_key, (void *)result); |
425ce2ed UD |
812 | THREAD_STAT(++(result->stat_lock_loop)); |
813 | next_to_use = result->next; | |
814 | ||
815 | return result; | |
816 | } | |
817 | #endif | |
818 | ||
fa8d436c UD |
819 | static mstate |
820 | internal_function | |
bf51f568 | 821 | arena_get2(mstate a_tsd, size_t size, mstate avoid_arena) |
fa8d436c UD |
822 | { |
823 | mstate a; | |
fa8d436c | 824 | |
425ce2ed | 825 | #ifdef PER_THREAD |
77cdc054 AS |
826 | static size_t narenas_limit; |
827 | ||
828 | a = get_free_list (); | |
829 | if (a == NULL) | |
830 | { | |
831 | /* Nothing immediately available, so generate a new arena. */ | |
832 | if (narenas_limit == 0) | |
833 | { | |
834 | if (mp_.arena_max != 0) | |
835 | narenas_limit = mp_.arena_max; | |
41b81892 | 836 | else if (narenas > mp_.arena_test) |
77cdc054 AS |
837 | { |
838 | int n = __get_nprocs (); | |
839 | ||
840 | if (n >= 1) | |
841 | narenas_limit = NARENAS_FROM_NCORES (n); | |
842 | else | |
843 | /* We have no information about the system. Assume two | |
844 | cores. */ | |
845 | narenas_limit = NARENAS_FROM_NCORES (2); | |
846 | } | |
847 | } | |
848 | repeat:; | |
849 | size_t n = narenas; | |
41b81892 UD |
850 | /* NB: the following depends on the fact that (size_t)0 - 1 is a |
851 | very large number and that the underflow is OK. If arena_max | |
852 | is set the value of arena_test is irrelevant. If arena_test | |
853 | is set but narenas is not yet larger or equal to arena_test | |
854 | narenas_limit is 0. There is no possibility for narenas to | |
855 | be too big for the test to always fail since there is not | |
856 | enough address space to create that many arenas. */ | |
857 | if (__builtin_expect (n <= narenas_limit - 1, 0)) | |
77cdc054 | 858 | { |
a5fb313c | 859 | if (catomic_compare_and_exchange_bool_acq (&narenas, n + 1, n)) |
77cdc054 AS |
860 | goto repeat; |
861 | a = _int_new_arena (size); | |
a5fb313c AS |
862 | if (__builtin_expect (a == NULL, 0)) |
863 | catomic_decrement (&narenas); | |
77cdc054 | 864 | } |
a5fb313c | 865 | else |
bf51f568 | 866 | a = reused_arena (avoid_arena); |
77cdc054 | 867 | } |
425ce2ed | 868 | #else |
fa8d436c UD |
869 | if(!a_tsd) |
870 | a = a_tsd = &main_arena; | |
871 | else { | |
872 | a = a_tsd->next; | |
873 | if(!a) { | |
874 | /* This can only happen while initializing the new arena. */ | |
875 | (void)mutex_lock(&main_arena.mutex); | |
876 | THREAD_STAT(++(main_arena.stat_lock_wait)); | |
877 | return &main_arena; | |
878 | } | |
879 | } | |
880 | ||
881 | /* Check the global, circularly linked list for available arenas. */ | |
8c7d3691 | 882 | bool retried = false; |
fa8d436c UD |
883 | repeat: |
884 | do { | |
885 | if(!mutex_trylock(&a->mutex)) { | |
8c7d3691 UD |
886 | if (retried) |
887 | (void)mutex_unlock(&list_lock); | |
fa8d436c | 888 | THREAD_STAT(++(a->stat_lock_loop)); |
22a89187 | 889 | tsd_setspecific(arena_key, (void *)a); |
fa8d436c UD |
890 | return a; |
891 | } | |
892 | a = a->next; | |
893 | } while(a != a_tsd); | |
894 | ||
895 | /* If not even the list_lock can be obtained, try again. This can | |
896 | happen during `atfork', or for example on systems where thread | |
897 | creation makes it temporarily impossible to obtain _any_ | |
898 | locks. */ | |
8c7d3691 UD |
899 | if(!retried && mutex_trylock(&list_lock)) { |
900 | /* We will block to not run in a busy loop. */ | |
901 | (void)mutex_lock(&list_lock); | |
902 | ||
903 | /* Since we blocked there might be an arena available now. */ | |
904 | retried = true; | |
fa8d436c UD |
905 | a = a_tsd; |
906 | goto repeat; | |
907 | } | |
fa8d436c UD |
908 | |
909 | /* Nothing immediately available, so generate a new arena. */ | |
910 | a = _int_new_arena(size); | |
fa8d436c | 911 | (void)mutex_unlock(&list_lock); |
425ce2ed | 912 | #endif |
fa8d436c | 913 | |
fa8d436c UD |
914 | return a; |
915 | } | |
916 | ||
425ce2ed UD |
917 | #ifdef PER_THREAD |
918 | static void __attribute__ ((section ("__libc_thread_freeres_fn"))) | |
919 | arena_thread_freeres (void) | |
920 | { | |
22a89187 | 921 | void *vptr = NULL; |
425ce2ed UD |
922 | mstate a = tsd_getspecific(arena_key, vptr); |
923 | tsd_setspecific(arena_key, NULL); | |
924 | ||
925 | if (a != NULL) | |
926 | { | |
927 | (void)mutex_lock(&list_lock); | |
928 | a->next_free = free_list; | |
929 | free_list = a; | |
930 | (void)mutex_unlock(&list_lock); | |
931 | } | |
932 | } | |
933 | text_set_element (__libc_thread_subfreeres, arena_thread_freeres); | |
934 | #endif | |
935 | ||
fa8d436c UD |
936 | /* |
937 | * Local variables: | |
938 | * c-basic-offset: 2 | |
939 | * End: | |
940 | */ |