1 /* 2 * NMALLOC.C - New Malloc (ported from kernel slab allocator) 3 * 4 * Copyright (c) 2003,2004,2009,2010 The DragonFly Project. All rights reserved. 5 * 6 * This code is derived from software contributed to The DragonFly Project 7 * by Matthew Dillon <dillon@backplane.com> and by 8 * Venkatesh Srinivas <me@endeavour.zapto.org>. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in 18 * the documentation and/or other materials provided with the 19 * distribution. 20 * 3. Neither the name of The DragonFly Project nor the names of its 21 * contributors may be used to endorse or promote products derived 22 * from this software without specific, prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 25 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 26 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 27 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 28 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 30 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 31 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 32 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 33 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 34 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * $Id: nmalloc.c,v 1.37 2010/07/23 08:20:35 vsrinivas Exp $ 38 */ 39 /* 40 * This module implements a slab allocator drop-in replacement for the 41 * libc malloc(). 42 * 43 * A slab allocator reserves a ZONE for each chunk size, then lays the 44 * chunks out in an array within the zone. Allocation and deallocation 45 * is nearly instantaneous, and overhead losses are limited to a fixed 46 * worst-case amount. 47 * 48 * The slab allocator does not have to pre-initialize the list of 49 * free chunks for each zone, and the underlying VM will not be 50 * touched at all beyond the zone header until an actual allocation 51 * needs it. 52 * 53 * Slab management and locking is done on a per-zone basis. 54 * 55 * Alloc Size Chunking Number of zones 56 * 0-127 8 16 57 * 128-255 16 8 58 * 256-511 32 8 59 * 512-1023 64 8 60 * 1024-2047 128 8 61 * 2048-4095 256 8 62 * 4096-8191 512 8 63 * 8192-16383 1024 8 64 * 16384-32767 2048 8 65 * 66 * Allocations >= ZoneLimit (16K) go directly to mmap and a hash table 67 * is used to locate for free. One and Two-page allocations use the 68 * zone mechanic to avoid excessive mmap()/munmap() calls. 69 * 70 * API FEATURES AND SIDE EFFECTS 71 * 72 * + power-of-2 sized allocations up to a page will be power-of-2 aligned. 73 * Above that power-of-2 sized allocations are page-aligned. Non 74 * power-of-2 sized allocations are aligned the same as the chunk 75 * size for their zone. 76 * + malloc(0) returns a special non-NULL value 77 * + ability to allocate arbitrarily large chunks of memory 78 * + realloc will reuse the passed pointer if possible, within the 79 * limitations of the zone chunking. 80 * 81 * Multithreaded enhancements for small allocations introduced August 2010. 82 * These are in the spirit of 'libumem'. See: 83 * Bonwick, J.; Adams, J. (2001). "Magazines and Vmem: Extending the 84 * slab allocator to many CPUs and arbitrary resources". In Proc. 2001 85 * USENIX Technical Conference. USENIX Association. 86 * 87 * Oversized allocations employ the BIGCACHE mechanic whereby large 88 * allocations may be handed significantly larger buffers, allowing them 89 * to avoid mmap/munmap operations even through significant realloc()s. 90 * The excess space is only trimmed if too many large allocations have been 91 * given this treatment. 92 * 93 * TUNING 94 * 95 * The value of the environment variable MALLOC_OPTIONS is a character string 96 * containing various flags to tune nmalloc. 97 * 98 * 'U' / ['u'] Generate / do not generate utrace entries for ktrace(1) 99 * This will generate utrace events for all malloc, 100 * realloc, and free calls. There are tools (mtrplay) to 101 * replay and allocation pattern or to graph heap structure 102 * (mtrgraph) which can interpret these logs. 103 * 'Z' / ['z'] Zero out / do not zero all allocations. 104 * Each new byte of memory allocated by malloc, realloc, or 105 * reallocf will be initialized to 0. This is intended for 106 * debugging and will affect performance negatively. 107 * 'H' / ['h'] Pass a hint to the kernel about pages unused by the 108 * allocation functions. 109 */ 110 111 /* cc -shared -fPIC -g -O -I/usr/src/lib/libc/include -o nmalloc.so nmalloc.c */ 112 113 #include "libc_private.h" 114 115 #include <sys/param.h> 116 #include <sys/types.h> 117 #include <sys/mman.h> 118 #include <sys/queue.h> 119 #include <sys/uio.h> 120 #include <sys/ktrace.h> 121 #include <stdio.h> 122 #include <stdint.h> 123 #include <stdlib.h> 124 #include <stdarg.h> 125 #include <stddef.h> 126 #include <unistd.h> 127 #include <string.h> 128 #include <fcntl.h> 129 #include <errno.h> 130 #include <pthread.h> 131 #include <machine/atomic.h> 132 133 #include "spinlock.h" 134 #include "un-namespace.h" 135 136 137 /* 138 * Linked list of large allocations 139 */ 140 typedef struct bigalloc { 141 struct bigalloc *next; /* hash link */ 142 void *base; /* base pointer */ 143 u_long active; /* bytes active */ 144 u_long bytes; /* bytes allocated */ 145 } *bigalloc_t; 146 147 /* 148 * Note that any allocations which are exact multiples of PAGE_SIZE, or 149 * which are >= ZALLOC_ZONE_LIMIT, will fall through to the kmem subsystem. 150 */ 151 #define ZALLOC_ZONE_LIMIT (16 * 1024) /* max slab-managed alloc */ 152 #define ZALLOC_MIN_ZONE_SIZE (32 * 1024) /* minimum zone size */ 153 #define ZALLOC_MAX_ZONE_SIZE (128 * 1024) /* maximum zone size */ 154 #define ZALLOC_ZONE_SIZE (64 * 1024) 155 #define ZALLOC_SLAB_MAGIC 0x736c6162 /* magic sanity */ 156 #define ZALLOC_SLAB_SLIDE 20 /* L1-cache skip */ 157 158 #if ZALLOC_ZONE_LIMIT == 16384 159 #define NZONES 72 160 #elif ZALLOC_ZONE_LIMIT == 32768 161 #define NZONES 80 162 #else 163 #error "I couldn't figure out NZONES" 164 #endif 165 166 /* 167 * Chunk structure for free elements 168 */ 169 typedef struct slchunk { 170 struct slchunk *c_Next; 171 } *slchunk_t; 172 173 /* 174 * The IN-BAND zone header is placed at the beginning of each zone. 175 */ 176 struct slglobaldata; 177 178 typedef struct slzone { 179 int32_t z_Magic; /* magic number for sanity check */ 180 int z_NFree; /* total free chunks / ualloc space */ 181 struct slzone *z_Next; /* ZoneAry[] link if z_NFree non-zero */ 182 int z_NMax; /* maximum free chunks */ 183 char *z_BasePtr; /* pointer to start of chunk array */ 184 int z_UIndex; /* current initial allocation index */ 185 int z_UEndIndex; /* last (first) allocation index */ 186 int z_ChunkSize; /* chunk size for validation */ 187 int z_FirstFreePg; /* chunk list on a page-by-page basis */ 188 int z_ZoneIndex; 189 int z_Flags; 190 struct slchunk *z_PageAry[ZALLOC_ZONE_SIZE / PAGE_SIZE]; 191 } *slzone_t; 192 193 typedef struct slglobaldata { 194 spinlock_t Spinlock; 195 slzone_t ZoneAry[NZONES];/* linked list of zones NFree > 0 */ 196 int JunkIndex; 197 } *slglobaldata_t; 198 199 #define SLZF_UNOTZEROD 0x0001 200 201 #define FASTSLABREALLOC 0x02 202 203 /* 204 * Misc constants. Note that allocations that are exact multiples of 205 * PAGE_SIZE, or exceed the zone limit, fall through to the kmem module. 206 * IN_SAME_PAGE_MASK is used to sanity-check the per-page free lists. 207 */ 208 #define MIN_CHUNK_SIZE 8 /* in bytes */ 209 #define MIN_CHUNK_MASK (MIN_CHUNK_SIZE - 1) 210 #define IN_SAME_PAGE_MASK (~(intptr_t)PAGE_MASK | MIN_CHUNK_MASK) 211 212 /* 213 * WARNING: A limited number of spinlocks are available, BIGXSIZE should 214 * not be larger then 64. 215 */ 216 #define BIGHSHIFT 10 /* bigalloc hash table */ 217 #define BIGHSIZE (1 << BIGHSHIFT) 218 #define BIGHMASK (BIGHSIZE - 1) 219 #define BIGXSIZE (BIGHSIZE / 16) /* bigalloc lock table */ 220 #define BIGXMASK (BIGXSIZE - 1) 221 222 /* 223 * BIGCACHE caches oversized allocations. Note that a linear search is 224 * performed, so do not make the cache too large. 225 * 226 * BIGCACHE will garbage-collect excess space when the excess exceeds the 227 * specified value. A relatively large number should be used here because 228 * garbage collection is expensive. 229 */ 230 #define BIGCACHE 16 231 #define BIGCACHE_MASK (BIGCACHE - 1) 232 #define BIGCACHE_LIMIT (1024 * 1024) /* size limit */ 233 #define BIGCACHE_EXCESS (16 * 1024 * 1024) /* garbage collect */ 234 235 #define SAFLAG_ZERO 0x0001 236 #define SAFLAG_PASSIVE 0x0002 237 238 /* 239 * Thread control 240 */ 241 242 #define arysize(ary) (sizeof(ary)/sizeof((ary)[0])) 243 244 #define MASSERT(exp) do { if (__predict_false(!(exp))) \ 245 _mpanic("assertion: %s in %s", \ 246 #exp, __func__); \ 247 } while (0) 248 249 /* 250 * Magazines 251 */ 252 253 #define M_MAX_ROUNDS 64 254 #define M_ZONE_ROUNDS 64 255 #define M_LOW_ROUNDS 32 256 #define M_INIT_ROUNDS 8 257 #define M_BURST_FACTOR 8 258 #define M_BURST_NSCALE 2 259 260 #define M_BURST 0x0001 261 #define M_BURST_EARLY 0x0002 262 263 struct magazine { 264 SLIST_ENTRY(magazine) nextmagazine; 265 266 int flags; 267 int capacity; /* Max rounds in this magazine */ 268 int rounds; /* Current number of free rounds */ 269 int burst_factor; /* Number of blocks to prefill with */ 270 int low_factor; /* Free till low_factor from full mag */ 271 void *objects[M_MAX_ROUNDS]; 272 }; 273 274 SLIST_HEAD(magazinelist, magazine); 275 276 static spinlock_t zone_mag_lock; 277 static spinlock_t depot_spinlock; 278 static struct magazine zone_magazine = { 279 .flags = M_BURST | M_BURST_EARLY, 280 .capacity = M_ZONE_ROUNDS, 281 .rounds = 0, 282 .burst_factor = M_BURST_FACTOR, 283 .low_factor = M_LOW_ROUNDS 284 }; 285 286 #define MAGAZINE_FULL(mp) (mp->rounds == mp->capacity) 287 #define MAGAZINE_NOTFULL(mp) (mp->rounds < mp->capacity) 288 #define MAGAZINE_EMPTY(mp) (mp->rounds == 0) 289 #define MAGAZINE_NOTEMPTY(mp) (mp->rounds != 0) 290 291 /* 292 * Each thread will have a pair of magazines per size-class (NZONES) 293 * The loaded magazine will support immediate allocations, the previous 294 * magazine will either be full or empty and can be swapped at need 295 */ 296 typedef struct magazine_pair { 297 struct magazine *loaded; 298 struct magazine *prev; 299 } magazine_pair; 300 301 /* A depot is a collection of magazines for a single zone. */ 302 typedef struct magazine_depot { 303 struct magazinelist full; 304 struct magazinelist empty; 305 spinlock_t lock; 306 } magazine_depot; 307 308 typedef struct thr_mags { 309 magazine_pair mags[NZONES]; 310 struct magazine *newmag; 311 int init; 312 } thr_mags; 313 314 /* 315 * With this attribute set, do not require a function call for accessing 316 * this variable when the code is compiled -fPIC. 317 * 318 * Must be empty for libc_rtld (similar to __thread). 319 */ 320 #ifdef __LIBC_RTLD 321 #define TLS_ATTRIBUTE 322 #else 323 #define TLS_ATTRIBUTE __attribute__ ((tls_model ("initial-exec"))) 324 #endif 325 326 static __thread thr_mags thread_mags TLS_ATTRIBUTE; 327 static pthread_key_t thread_mags_key; 328 static pthread_once_t thread_mags_once = PTHREAD_ONCE_INIT; 329 static magazine_depot depots[NZONES]; 330 331 /* 332 * Fixed globals (not per-cpu) 333 */ 334 static const int ZoneSize = ZALLOC_ZONE_SIZE; 335 static const int ZoneLimit = ZALLOC_ZONE_LIMIT; 336 static const int ZonePageCount = ZALLOC_ZONE_SIZE / PAGE_SIZE; 337 static const int ZoneMask = ZALLOC_ZONE_SIZE - 1; 338 339 static int opt_madvise = 0; 340 static int opt_utrace = 0; 341 static int g_malloc_flags = 0; 342 static struct slglobaldata SLGlobalData; 343 static bigalloc_t bigalloc_array[BIGHSIZE]; 344 static spinlock_t bigspin_array[BIGXSIZE]; 345 static volatile void *bigcache_array[BIGCACHE]; /* atomic swap */ 346 static volatile size_t bigcache_size_array[BIGCACHE]; /* SMP races ok */ 347 static volatile int bigcache_index; /* SMP races ok */ 348 static int malloc_panic; 349 static size_t excess_alloc; /* excess big allocs */ 350 351 static void *_slaballoc(size_t size, int flags); 352 static void *_slabrealloc(void *ptr, size_t size); 353 static void _slabfree(void *ptr, int, bigalloc_t *); 354 static void *_vmem_alloc(size_t bytes, size_t align, int flags); 355 static void _vmem_free(void *ptr, size_t bytes); 356 static void *magazine_alloc(struct magazine *, int *); 357 static int magazine_free(struct magazine *, void *); 358 static void *mtmagazine_alloc(int zi); 359 static int mtmagazine_free(int zi, void *); 360 static void mtmagazine_init(void); 361 static void mtmagazine_destructor(void *); 362 static slzone_t zone_alloc(int flags); 363 static void zone_free(void *z); 364 static void _mpanic(const char *ctl, ...) __printflike(1, 2); 365 static void malloc_init(void) __constructor(101); 366 367 struct nmalloc_utrace { 368 void *p; 369 size_t s; 370 void *r; 371 }; 372 373 #define UTRACE(a, b, c) \ 374 if (opt_utrace) { \ 375 struct nmalloc_utrace ut = { \ 376 .p = (a), \ 377 .s = (b), \ 378 .r = (c) \ 379 }; \ 380 utrace(&ut, sizeof(ut)); \ 381 } 382 383 static void 384 malloc_init(void) 385 { 386 const char *p = NULL; 387 388 if (issetugid() == 0) 389 p = getenv("MALLOC_OPTIONS"); 390 391 for (; p != NULL && *p != '\0'; p++) { 392 switch(*p) { 393 case 'u': opt_utrace = 0; break; 394 case 'U': opt_utrace = 1; break; 395 case 'h': opt_madvise = 0; break; 396 case 'H': opt_madvise = 1; break; 397 case 'z': g_malloc_flags = 0; break; 398 case 'Z': g_malloc_flags = SAFLAG_ZERO; break; 399 default: 400 break; 401 } 402 } 403 404 UTRACE((void *) -1, 0, NULL); 405 } 406 407 /* 408 * We have to install a handler for nmalloc thread teardowns when 409 * the thread is created. We cannot delay this because destructors in 410 * sophisticated userland programs can call malloc() for the first time 411 * during their thread exit. 412 * 413 * This routine is called directly from pthreads. 414 */ 415 void 416 _nmalloc_thr_init(void) 417 { 418 static int init_once; 419 thr_mags *tp; 420 421 /* 422 * Disallow mtmagazine operations until the mtmagazine is 423 * initialized. 424 */ 425 tp = &thread_mags; 426 tp->init = -1; 427 428 if (init_once == 0) { 429 init_once = 1; 430 pthread_once(&thread_mags_once, mtmagazine_init); 431 } 432 pthread_setspecific(thread_mags_key, tp); 433 tp->init = 1; 434 } 435 436 void 437 _nmalloc_thr_prepfork(void) 438 { 439 if (__isthreaded) { 440 _SPINLOCK(&zone_mag_lock); 441 _SPINLOCK(&depot_spinlock); 442 } 443 } 444 445 void 446 _nmalloc_thr_parentfork(void) 447 { 448 if (__isthreaded) { 449 _SPINUNLOCK(&depot_spinlock); 450 _SPINUNLOCK(&zone_mag_lock); 451 } 452 } 453 454 void 455 _nmalloc_thr_childfork(void) 456 { 457 if (__isthreaded) { 458 _SPINUNLOCK(&depot_spinlock); 459 _SPINUNLOCK(&zone_mag_lock); 460 } 461 } 462 463 /* 464 * Thread locks. 465 */ 466 static __inline void 467 slgd_lock(slglobaldata_t slgd) 468 { 469 if (__isthreaded) 470 _SPINLOCK(&slgd->Spinlock); 471 } 472 473 static __inline void 474 slgd_unlock(slglobaldata_t slgd) 475 { 476 if (__isthreaded) 477 _SPINUNLOCK(&slgd->Spinlock); 478 } 479 480 static __inline void 481 depot_lock(magazine_depot *dp) 482 { 483 if (__isthreaded) 484 _SPINLOCK(&depot_spinlock); 485 #if 0 486 if (__isthreaded) 487 _SPINLOCK(&dp->lock); 488 #endif 489 } 490 491 static __inline void 492 depot_unlock(magazine_depot *dp) 493 { 494 if (__isthreaded) 495 _SPINUNLOCK(&depot_spinlock); 496 #if 0 497 if (__isthreaded) 498 _SPINUNLOCK(&dp->lock); 499 #endif 500 } 501 502 static __inline void 503 zone_magazine_lock(void) 504 { 505 if (__isthreaded) 506 _SPINLOCK(&zone_mag_lock); 507 } 508 509 static __inline void 510 zone_magazine_unlock(void) 511 { 512 if (__isthreaded) 513 _SPINUNLOCK(&zone_mag_lock); 514 } 515 516 static __inline void 517 swap_mags(magazine_pair *mp) 518 { 519 struct magazine *tmp; 520 tmp = mp->loaded; 521 mp->loaded = mp->prev; 522 mp->prev = tmp; 523 } 524 525 /* 526 * bigalloc hashing and locking support. 527 * 528 * Return an unmasked hash code for the passed pointer. 529 */ 530 static __inline int 531 _bigalloc_hash(void *ptr) 532 { 533 int hv; 534 535 hv = ((int)(intptr_t)ptr >> PAGE_SHIFT) ^ 536 ((int)(intptr_t)ptr >> (PAGE_SHIFT + BIGHSHIFT)); 537 538 return(hv); 539 } 540 541 /* 542 * Lock the hash chain and return a pointer to its base for the specified 543 * address. 544 */ 545 static __inline bigalloc_t * 546 bigalloc_lock(void *ptr) 547 { 548 int hv = _bigalloc_hash(ptr); 549 bigalloc_t *bigp; 550 551 bigp = &bigalloc_array[hv & BIGHMASK]; 552 if (__isthreaded) 553 _SPINLOCK(&bigspin_array[hv & BIGXMASK]); 554 return(bigp); 555 } 556 557 /* 558 * Lock the hash chain and return a pointer to its base for the specified 559 * address. 560 * 561 * BUT, if the hash chain is empty, just return NULL and do not bother 562 * to lock anything. 563 */ 564 static __inline bigalloc_t * 565 bigalloc_check_and_lock(void *ptr) 566 { 567 int hv = _bigalloc_hash(ptr); 568 bigalloc_t *bigp; 569 570 bigp = &bigalloc_array[hv & BIGHMASK]; 571 if (*bigp == NULL) 572 return(NULL); 573 if (__isthreaded) { 574 _SPINLOCK(&bigspin_array[hv & BIGXMASK]); 575 } 576 return(bigp); 577 } 578 579 static __inline void 580 bigalloc_unlock(void *ptr) 581 { 582 int hv; 583 584 if (__isthreaded) { 585 hv = _bigalloc_hash(ptr); 586 _SPINUNLOCK(&bigspin_array[hv & BIGXMASK]); 587 } 588 } 589 590 /* 591 * Find a bigcache entry that might work for the allocation. SMP races are 592 * ok here except for the swap (that is, it is ok if bigcache_size_array[i] 593 * is wrong or if a NULL or too-small big is returned). 594 * 595 * Generally speaking it is ok to find a large entry even if the bytes 596 * requested are relatively small (but still oversized), because we really 597 * don't know *what* the application is going to do with the buffer. 598 */ 599 static __inline 600 bigalloc_t 601 bigcache_find_alloc(size_t bytes) 602 { 603 bigalloc_t big = NULL; 604 size_t test; 605 int i; 606 607 for (i = 0; i < BIGCACHE; ++i) { 608 test = bigcache_size_array[i]; 609 if (bytes <= test) { 610 bigcache_size_array[i] = 0; 611 big = atomic_swap_ptr(&bigcache_array[i], NULL); 612 break; 613 } 614 } 615 return big; 616 } 617 618 /* 619 * Free a bigcache entry, possibly returning one that the caller really must 620 * free. This is used to cache recent oversized memory blocks. Only 621 * big blocks smaller than BIGCACHE_LIMIT will be cached this way, so try 622 * to collect the biggest ones we can that are under the limit. 623 */ 624 static __inline 625 bigalloc_t 626 bigcache_find_free(bigalloc_t big) 627 { 628 int i; 629 int j; 630 int b; 631 632 b = ++bigcache_index; 633 for (i = 0; i < BIGCACHE; ++i) { 634 j = (b + i) & BIGCACHE_MASK; 635 if (bigcache_size_array[j] < big->bytes) { 636 bigcache_size_array[j] = big->bytes; 637 big = atomic_swap_ptr(&bigcache_array[j], big); 638 break; 639 } 640 } 641 return big; 642 } 643 644 static __inline 645 void 646 handle_excess_big(void) 647 { 648 int i; 649 bigalloc_t big; 650 bigalloc_t *bigp; 651 652 if (excess_alloc <= BIGCACHE_EXCESS) 653 return; 654 655 for (i = 0; i < BIGHSIZE; ++i) { 656 bigp = &bigalloc_array[i]; 657 if (*bigp == NULL) 658 continue; 659 if (__isthreaded) 660 _SPINLOCK(&bigspin_array[i & BIGXMASK]); 661 for (big = *bigp; big; big = big->next) { 662 if (big->active < big->bytes) { 663 MASSERT((big->active & PAGE_MASK) == 0); 664 MASSERT((big->bytes & PAGE_MASK) == 0); 665 munmap((char *)big->base + big->active, 666 big->bytes - big->active); 667 atomic_add_long(&excess_alloc, 668 big->active - big->bytes); 669 big->bytes = big->active; 670 } 671 } 672 if (__isthreaded) 673 _SPINUNLOCK(&bigspin_array[i & BIGXMASK]); 674 } 675 } 676 677 /* 678 * Calculate the zone index for the allocation request size and set the 679 * allocation request size to that particular zone's chunk size. 680 */ 681 static __inline int 682 zoneindex(size_t *bytes, size_t *chunking) 683 { 684 size_t n = (unsigned int)*bytes; /* unsigned for shift opt */ 685 686 /* 687 * This used to be 8-byte chunks and 16 zones for n < 128. 688 * However some instructions may require 16-byte alignment 689 * (aka SIMD) and programs might not request an aligned size 690 * (aka GCC-7), so change this as follows: 691 * 692 * 0-15 bytes 8-byte alignment in two zones (0-1) 693 * 16-127 bytes 16-byte alignment in four zones (3-10) 694 * zone index 2 and 11-15 are currently unused. 695 */ 696 if (n < 16) { 697 *bytes = n = (n + 7) & ~7; 698 *chunking = 8; 699 return(n / 8 - 1); /* 8 byte chunks, 2 zones */ 700 /* zones 0,1, zone 2 is unused */ 701 } 702 if (n < 128) { 703 *bytes = n = (n + 15) & ~15; 704 *chunking = 16; 705 return(n / 16 + 2); /* 16 byte chunks, 8 zones */ 706 /* zones 3-10, zones 11-15 unused */ 707 } 708 if (n < 256) { 709 *bytes = n = (n + 15) & ~15; 710 *chunking = 16; 711 return(n / 16 + 7); 712 } 713 if (n < 8192) { 714 if (n < 512) { 715 *bytes = n = (n + 31) & ~31; 716 *chunking = 32; 717 return(n / 32 + 15); 718 } 719 if (n < 1024) { 720 *bytes = n = (n + 63) & ~63; 721 *chunking = 64; 722 return(n / 64 + 23); 723 } 724 if (n < 2048) { 725 *bytes = n = (n + 127) & ~127; 726 *chunking = 128; 727 return(n / 128 + 31); 728 } 729 if (n < 4096) { 730 *bytes = n = (n + 255) & ~255; 731 *chunking = 256; 732 return(n / 256 + 39); 733 } 734 *bytes = n = (n + 511) & ~511; 735 *chunking = 512; 736 return(n / 512 + 47); 737 } 738 #if ZALLOC_ZONE_LIMIT > 8192 739 if (n < 16384) { 740 *bytes = n = (n + 1023) & ~1023; 741 *chunking = 1024; 742 return(n / 1024 + 55); 743 } 744 #endif 745 #if ZALLOC_ZONE_LIMIT > 16384 746 if (n < 32768) { 747 *bytes = n = (n + 2047) & ~2047; 748 *chunking = 2048; 749 return(n / 2048 + 63); 750 } 751 #endif 752 _mpanic("Unexpected byte count %zu", n); 753 return(0); 754 } 755 756 /* 757 * malloc() - call internal slab allocator 758 */ 759 void * 760 __malloc(size_t size) 761 { 762 void *ptr; 763 764 ptr = _slaballoc(size, 0); 765 if (ptr == NULL) 766 errno = ENOMEM; 767 else 768 UTRACE(0, size, ptr); 769 return(ptr); 770 } 771 772 #define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 4)) 773 774 /* 775 * calloc() - call internal slab allocator 776 */ 777 void * 778 __calloc(size_t number, size_t size) 779 { 780 void *ptr; 781 782 if ((number >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && 783 number > 0 && SIZE_MAX / number < size) { 784 errno = ENOMEM; 785 return(NULL); 786 } 787 788 ptr = _slaballoc(number * size, SAFLAG_ZERO); 789 if (ptr == NULL) 790 errno = ENOMEM; 791 else 792 UTRACE(0, number * size, ptr); 793 return(ptr); 794 } 795 796 /* 797 * realloc() (SLAB ALLOCATOR) 798 * 799 * We do not attempt to optimize this routine beyond reusing the same 800 * pointer if the new size fits within the chunking of the old pointer's 801 * zone. 802 */ 803 void * 804 __realloc(void *ptr, size_t size) 805 { 806 void *ret; 807 ret = _slabrealloc(ptr, size); 808 if (ret == NULL) 809 errno = ENOMEM; 810 else 811 UTRACE(ptr, size, ret); 812 return(ret); 813 } 814 815 /* 816 * posix_memalign() 817 * 818 * Allocate (size) bytes with a alignment of (alignment), where (alignment) 819 * is a power of 2 >= sizeof(void *). 820 * 821 * The slab allocator will allocate on power-of-2 boundaries up to 822 * at least PAGE_SIZE. We use the zoneindex mechanic to find a 823 * zone matching the requirements, and _vmem_alloc() otherwise. 824 */ 825 int 826 __posix_memalign(void **memptr, size_t alignment, size_t size) 827 { 828 bigalloc_t *bigp; 829 bigalloc_t big; 830 size_t chunking; 831 int zi __unused; 832 833 /* 834 * OpenGroup spec issue 6 checks 835 */ 836 if ((alignment | (alignment - 1)) + 1 != (alignment << 1)) { 837 *memptr = NULL; 838 return(EINVAL); 839 } 840 if (alignment < sizeof(void *)) { 841 *memptr = NULL; 842 return(EINVAL); 843 } 844 845 /* 846 * Our zone mechanism guarantees same-sized alignment for any 847 * power-of-2 allocation. If size is a power-of-2 and reasonable 848 * we can just call _slaballoc() and be done. We round size up 849 * to the nearest alignment boundary to improve our odds of 850 * it becoming a power-of-2 if it wasn't before. 851 */ 852 if (size <= alignment) 853 size = alignment; 854 else 855 size = (size + alignment - 1) & ~(size_t)(alignment - 1); 856 if (size < PAGE_SIZE && (size | (size - 1)) + 1 == (size << 1)) { 857 *memptr = _slaballoc(size, 0); 858 return(*memptr ? 0 : ENOMEM); 859 } 860 861 /* 862 * Otherwise locate a zone with a chunking that matches 863 * the requested alignment, within reason. Consider two cases: 864 * 865 * (1) A 1K allocation on a 32-byte alignment. The first zoneindex 866 * we find will be the best fit because the chunking will be 867 * greater or equal to the alignment. 868 * 869 * (2) A 513 allocation on a 256-byte alignment. In this case 870 * the first zoneindex we find will be for 576 byte allocations 871 * with a chunking of 64, which is not sufficient. To fix this 872 * we simply find the nearest power-of-2 >= size and use the 873 * same side-effect of _slaballoc() which guarantees 874 * same-alignment on a power-of-2 allocation. 875 */ 876 if (size < PAGE_SIZE) { 877 zi = zoneindex(&size, &chunking); 878 if (chunking >= alignment) { 879 *memptr = _slaballoc(size, 0); 880 return(*memptr ? 0 : ENOMEM); 881 } 882 if (size >= 1024) 883 alignment = 1024; 884 if (size >= 16384) 885 alignment = 16384; 886 while (alignment < size) 887 alignment <<= 1; 888 *memptr = _slaballoc(alignment, 0); 889 return(*memptr ? 0 : ENOMEM); 890 } 891 892 /* 893 * If the slab allocator cannot handle it use vmem_alloc(). 894 * 895 * Alignment must be adjusted up to at least PAGE_SIZE in this case. 896 */ 897 if (alignment < PAGE_SIZE) 898 alignment = PAGE_SIZE; 899 if (size < alignment) 900 size = alignment; 901 size = (size + PAGE_MASK) & ~(size_t)PAGE_MASK; 902 *memptr = _vmem_alloc(size, alignment, 0); 903 if (*memptr == NULL) 904 return(ENOMEM); 905 906 big = _slaballoc(sizeof(struct bigalloc), 0); 907 if (big == NULL) { 908 _vmem_free(*memptr, size); 909 *memptr = NULL; 910 return(ENOMEM); 911 } 912 bigp = bigalloc_lock(*memptr); 913 big->base = *memptr; 914 big->active = size; 915 big->bytes = size; /* no excess */ 916 big->next = *bigp; 917 *bigp = big; 918 bigalloc_unlock(*memptr); 919 920 return(0); 921 } 922 923 /* 924 * free() (SLAB ALLOCATOR) - do the obvious 925 */ 926 void 927 __free(void *ptr) 928 { 929 UTRACE(ptr, 0, 0); 930 _slabfree(ptr, 0, NULL); 931 } 932 933 /* 934 * _slaballoc() (SLAB ALLOCATOR) 935 * 936 * Allocate memory via the slab allocator. If the request is too large, 937 * or if it page-aligned beyond a certain size, we fall back to the 938 * KMEM subsystem 939 */ 940 static void * 941 _slaballoc(size_t size, int flags) 942 { 943 slzone_t z; 944 slchunk_t chunk; 945 slglobaldata_t slgd; 946 size_t chunking; 947 int zi; 948 int off; 949 void *obj; 950 951 /* 952 * Handle the degenerate size == 0 case. Yes, this does happen. 953 * Return a special pointer. This is to maintain compatibility with 954 * the original malloc implementation. Certain devices, such as the 955 * adaptec driver, not only allocate 0 bytes, they check for NULL and 956 * also realloc() later on. Joy. 957 */ 958 if (size == 0) 959 size = 1; 960 961 /* Capture global flags */ 962 flags |= g_malloc_flags; 963 964 /* 965 * Handle large allocations directly. There should not be very many 966 * of these so performance is not a big issue. 967 * 968 * The backend allocator is pretty nasty on a SMP system. Use the 969 * slab allocator for one and two page-sized chunks even though we 970 * lose some efficiency. 971 */ 972 if (size >= ZoneLimit || 973 ((size & PAGE_MASK) == 0 && size > PAGE_SIZE*2)) { 974 bigalloc_t big; 975 bigalloc_t *bigp; 976 977 /* 978 * Page-align and cache-color in case of virtually indexed 979 * physically tagged L1 caches (aka SandyBridge). No sweat 980 * otherwise, so just do it. 981 * 982 * (don't count as excess). 983 */ 984 size = (size + PAGE_MASK) & ~(size_t)PAGE_MASK; 985 if ((size & (PAGE_SIZE * 2 - 1)) == 0) 986 size += PAGE_SIZE; 987 988 /* 989 * Try to reuse a cached big block to avoid mmap'ing. If it 990 * turns out not to fit our requirements we throw it away 991 * and allocate normally. 992 */ 993 big = NULL; 994 if (size <= BIGCACHE_LIMIT) { 995 big = bigcache_find_alloc(size); 996 if (big && big->bytes < size) { 997 _slabfree(big->base, FASTSLABREALLOC, &big); 998 big = NULL; 999 } 1000 } 1001 if (big) { 1002 chunk = big->base; 1003 if (flags & SAFLAG_ZERO) 1004 bzero(chunk, size); 1005 } else { 1006 chunk = _vmem_alloc(size, PAGE_SIZE, flags); 1007 if (chunk == NULL) 1008 return(NULL); 1009 1010 big = _slaballoc(sizeof(struct bigalloc), 0); 1011 if (big == NULL) { 1012 _vmem_free(chunk, size); 1013 return(NULL); 1014 } 1015 big->base = chunk; 1016 big->bytes = size; 1017 } 1018 big->active = size; 1019 1020 bigp = bigalloc_lock(chunk); 1021 if (big->active < big->bytes) { 1022 atomic_add_long(&excess_alloc, 1023 big->bytes - big->active); 1024 } 1025 big->next = *bigp; 1026 *bigp = big; 1027 bigalloc_unlock(chunk); 1028 handle_excess_big(); 1029 1030 return(chunk); 1031 } 1032 1033 /* Compute allocation zone; zoneindex will panic on excessive sizes */ 1034 zi = zoneindex(&size, &chunking); 1035 MASSERT(zi < NZONES); 1036 1037 obj = mtmagazine_alloc(zi); 1038 if (obj != NULL) { 1039 if (flags & SAFLAG_ZERO) 1040 bzero(obj, size); 1041 return (obj); 1042 } 1043 1044 slgd = &SLGlobalData; 1045 slgd_lock(slgd); 1046 1047 /* 1048 * Attempt to allocate out of an existing zone. If all zones are 1049 * exhausted pull one off the free list or allocate a new one. 1050 */ 1051 if ((z = slgd->ZoneAry[zi]) == NULL) { 1052 z = zone_alloc(flags); 1053 if (z == NULL) 1054 goto fail; 1055 1056 /* 1057 * How big is the base structure? 1058 */ 1059 off = sizeof(struct slzone); 1060 1061 /* 1062 * Align the storage in the zone based on the chunking. 1063 * 1064 * Guarantee power-of-2 alignment for power-of-2-sized 1065 * chunks. Otherwise align based on the chunking size 1066 * (typically 8 or 16 bytes for small allocations). 1067 * 1068 * NOTE: Allocations >= ZoneLimit are governed by the 1069 * bigalloc code and typically only guarantee page-alignment. 1070 * 1071 * Set initial conditions for UIndex near the zone header 1072 * to reduce unecessary page faults, vs semi-randomization 1073 * to improve L1 cache saturation. 1074 */ 1075 if ((size | (size - 1)) + 1 == (size << 1)) 1076 off = roundup2(off, size); 1077 else 1078 off = roundup2(off, chunking); 1079 z->z_Magic = ZALLOC_SLAB_MAGIC; 1080 z->z_ZoneIndex = zi; 1081 z->z_NMax = (ZoneSize - off) / size; 1082 z->z_NFree = z->z_NMax; 1083 z->z_BasePtr = (char *)z + off; 1084 z->z_UIndex = z->z_UEndIndex = 0; 1085 z->z_ChunkSize = size; 1086 z->z_FirstFreePg = ZonePageCount; 1087 z->z_Next = slgd->ZoneAry[zi]; 1088 slgd->ZoneAry[zi] = z; 1089 if ((z->z_Flags & SLZF_UNOTZEROD) == 0) { 1090 flags &= ~SAFLAG_ZERO; /* already zero'd */ 1091 flags |= SAFLAG_PASSIVE; 1092 } 1093 1094 /* 1095 * Slide the base index for initial allocations out of the 1096 * next zone we create so we do not over-weight the lower 1097 * part of the cpu memory caches. 1098 */ 1099 slgd->JunkIndex = (slgd->JunkIndex + ZALLOC_SLAB_SLIDE) 1100 & (ZALLOC_MAX_ZONE_SIZE - 1); 1101 } 1102 1103 /* 1104 * Ok, we have a zone from which at least one chunk is available. 1105 * 1106 * Remove us from the ZoneAry[] when we become empty 1107 */ 1108 MASSERT(z->z_NFree > 0); 1109 1110 if (--z->z_NFree == 0) { 1111 slgd->ZoneAry[zi] = z->z_Next; 1112 z->z_Next = NULL; 1113 } 1114 1115 /* 1116 * Locate a chunk in a free page. This attempts to localize 1117 * reallocations into earlier pages without us having to sort 1118 * the chunk list. A chunk may still overlap a page boundary. 1119 */ 1120 while (z->z_FirstFreePg < ZonePageCount) { 1121 if ((chunk = z->z_PageAry[z->z_FirstFreePg]) != NULL) { 1122 MASSERT((uintptr_t)chunk & ZoneMask); 1123 z->z_PageAry[z->z_FirstFreePg] = chunk->c_Next; 1124 goto done; 1125 } 1126 ++z->z_FirstFreePg; 1127 } 1128 1129 /* 1130 * No chunks are available but NFree said we had some memory, 1131 * so it must be available in the never-before-used-memory 1132 * area governed by UIndex. The consequences are very 1133 * serious if our zone got corrupted so we use an explicit 1134 * panic rather then a KASSERT. 1135 */ 1136 chunk = (slchunk_t)(z->z_BasePtr + z->z_UIndex * size); 1137 1138 if (++z->z_UIndex == z->z_NMax) 1139 z->z_UIndex = 0; 1140 if (z->z_UIndex == z->z_UEndIndex) { 1141 if (z->z_NFree != 0) 1142 _mpanic("slaballoc: corrupted zone"); 1143 } 1144 1145 if ((z->z_Flags & SLZF_UNOTZEROD) == 0) { 1146 flags &= ~SAFLAG_ZERO; 1147 flags |= SAFLAG_PASSIVE; 1148 } 1149 1150 done: 1151 slgd_unlock(slgd); 1152 if (flags & SAFLAG_ZERO) 1153 bzero(chunk, size); 1154 return(chunk); 1155 fail: 1156 slgd_unlock(slgd); 1157 return(NULL); 1158 } 1159 1160 /* 1161 * Reallocate memory within the chunk 1162 */ 1163 static void * 1164 _slabrealloc(void *ptr, size_t size) 1165 { 1166 bigalloc_t *bigp; 1167 void *nptr; 1168 slzone_t z; 1169 size_t chunking; 1170 1171 if (ptr == NULL) { 1172 return(_slaballoc(size, 0)); 1173 } 1174 1175 if (size == 0) 1176 size = 1; 1177 1178 /* 1179 * Handle oversized allocations. 1180 */ 1181 if ((bigp = bigalloc_check_and_lock(ptr)) != NULL) { 1182 bigalloc_t big; 1183 size_t bigbytes; 1184 1185 while ((big = *bigp) != NULL) { 1186 if (big->base == ptr) { 1187 size = (size + PAGE_MASK) & ~(size_t)PAGE_MASK; 1188 bigbytes = big->bytes; 1189 1190 /* 1191 * If it already fits determine if it makes 1192 * sense to shrink/reallocate. Try to optimize 1193 * programs which stupidly make incremental 1194 * reallocations larger or smaller by scaling 1195 * the allocation. Also deal with potential 1196 * coloring. 1197 */ 1198 if (size >= (bigbytes >> 1) && 1199 size <= bigbytes) { 1200 if (big->active != size) { 1201 atomic_add_long(&excess_alloc, 1202 big->active - 1203 size); 1204 } 1205 big->active = size; 1206 bigalloc_unlock(ptr); 1207 return(ptr); 1208 } 1209 1210 /* 1211 * For large reallocations, allocate more space 1212 * than we need to try to avoid excessive 1213 * reallocations later on. 1214 */ 1215 chunking = size + (size >> 3); 1216 chunking = (chunking + PAGE_MASK) & 1217 ~(size_t)PAGE_MASK; 1218 1219 /* 1220 * Try to allocate adjacently in case the 1221 * program is idiotically realloc()ing a 1222 * huge memory block just slightly bigger. 1223 * (llvm's llc tends to do this a lot). 1224 * 1225 * (MAP_TRYFIXED forces mmap to fail if there 1226 * is already something at the address). 1227 */ 1228 if (chunking > bigbytes) { 1229 char *addr; 1230 int errno_save = errno; 1231 1232 addr = mmap((char *)ptr + bigbytes, 1233 chunking - bigbytes, 1234 PROT_READ|PROT_WRITE, 1235 MAP_PRIVATE|MAP_ANON| 1236 MAP_TRYFIXED, 1237 -1, 0); 1238 errno = errno_save; 1239 if (addr == (char *)ptr + bigbytes) { 1240 atomic_add_long(&excess_alloc, 1241 big->active - 1242 big->bytes + 1243 chunking - 1244 size); 1245 big->bytes = chunking; 1246 big->active = size; 1247 bigalloc_unlock(ptr); 1248 1249 return(ptr); 1250 } 1251 MASSERT((void *)addr == MAP_FAILED); 1252 } 1253 1254 /* 1255 * Failed, unlink big and allocate fresh. 1256 * (note that we have to leave (big) intact 1257 * in case the slaballoc fails). 1258 */ 1259 *bigp = big->next; 1260 bigalloc_unlock(ptr); 1261 if ((nptr = _slaballoc(size, 0)) == NULL) { 1262 /* Relink block */ 1263 bigp = bigalloc_lock(ptr); 1264 big->next = *bigp; 1265 *bigp = big; 1266 bigalloc_unlock(ptr); 1267 return(NULL); 1268 } 1269 if (size > bigbytes) 1270 size = bigbytes; 1271 bcopy(ptr, nptr, size); 1272 atomic_add_long(&excess_alloc, big->active - 1273 big->bytes); 1274 _slabfree(ptr, FASTSLABREALLOC, &big); 1275 1276 return(nptr); 1277 } 1278 bigp = &big->next; 1279 } 1280 bigalloc_unlock(ptr); 1281 handle_excess_big(); 1282 } 1283 1284 /* 1285 * Get the original allocation's zone. If the new request winds 1286 * up using the same chunk size we do not have to do anything. 1287 * 1288 * NOTE: We don't have to lock the globaldata here, the fields we 1289 * access here will not change at least as long as we have control 1290 * over the allocation. 1291 */ 1292 z = (slzone_t)((uintptr_t)ptr & ~(uintptr_t)ZoneMask); 1293 MASSERT(z->z_Magic == ZALLOC_SLAB_MAGIC); 1294 1295 /* 1296 * Use zoneindex() to chunk-align the new size, as long as the 1297 * new size is not too large. 1298 */ 1299 if (size < ZoneLimit) { 1300 zoneindex(&size, &chunking); 1301 if (z->z_ChunkSize == size) { 1302 return(ptr); 1303 } 1304 } 1305 1306 /* 1307 * Allocate memory for the new request size and copy as appropriate. 1308 */ 1309 if ((nptr = _slaballoc(size, 0)) != NULL) { 1310 if (size > z->z_ChunkSize) 1311 size = z->z_ChunkSize; 1312 bcopy(ptr, nptr, size); 1313 _slabfree(ptr, 0, NULL); 1314 } 1315 1316 return(nptr); 1317 } 1318 1319 /* 1320 * free (SLAB ALLOCATOR) 1321 * 1322 * Free a memory block previously allocated by malloc. Note that we do not 1323 * attempt to uplodate ks_loosememuse as MP races could prevent us from 1324 * checking memory limits in malloc. 1325 * 1326 * flags: 1327 * FASTSLABREALLOC Fast call from realloc, *rbigp already 1328 * unlinked. 1329 * 1330 * MPSAFE 1331 */ 1332 static void 1333 _slabfree(void *ptr, int flags, bigalloc_t *rbigp) 1334 { 1335 slzone_t z; 1336 slchunk_t chunk; 1337 bigalloc_t big; 1338 bigalloc_t *bigp; 1339 slglobaldata_t slgd; 1340 size_t size; 1341 int zi; 1342 int pgno; 1343 1344 /* Fast realloc path for big allocations */ 1345 if (flags & FASTSLABREALLOC) { 1346 big = *rbigp; 1347 goto fastslabrealloc; 1348 } 1349 1350 /* 1351 * Handle NULL frees and special 0-byte allocations 1352 */ 1353 if (ptr == NULL) 1354 return; 1355 1356 /* 1357 * Handle oversized allocations. 1358 */ 1359 if ((bigp = bigalloc_check_and_lock(ptr)) != NULL) { 1360 while ((big = *bigp) != NULL) { 1361 if (big->base == ptr) { 1362 *bigp = big->next; 1363 atomic_add_long(&excess_alloc, big->active - 1364 big->bytes); 1365 bigalloc_unlock(ptr); 1366 1367 /* 1368 * Try to stash the block we are freeing, 1369 * potentially receiving another block in 1370 * return which must be freed. 1371 */ 1372 fastslabrealloc: 1373 if (big->bytes <= BIGCACHE_LIMIT) { 1374 big = bigcache_find_free(big); 1375 if (big == NULL) 1376 return; 1377 } 1378 ptr = big->base; /* reload */ 1379 size = big->bytes; 1380 _slabfree(big, 0, NULL); 1381 _vmem_free(ptr, size); 1382 return; 1383 } 1384 bigp = &big->next; 1385 } 1386 bigalloc_unlock(ptr); 1387 handle_excess_big(); 1388 } 1389 1390 /* 1391 * Zone case. Figure out the zone based on the fact that it is 1392 * ZoneSize aligned. 1393 */ 1394 z = (slzone_t)((uintptr_t)ptr & ~(uintptr_t)ZoneMask); 1395 MASSERT(z->z_Magic == ZALLOC_SLAB_MAGIC); 1396 1397 size = z->z_ChunkSize; 1398 zi = z->z_ZoneIndex; 1399 1400 if (g_malloc_flags & SAFLAG_ZERO) 1401 bzero(ptr, size); 1402 1403 if (mtmagazine_free(zi, ptr) == 0) 1404 return; 1405 1406 pgno = ((char *)ptr - (char *)z) >> PAGE_SHIFT; 1407 chunk = ptr; 1408 slgd = &SLGlobalData; 1409 slgd_lock(slgd); 1410 1411 /* 1412 * Add this free non-zero'd chunk to a linked list for reuse, adjust 1413 * z_FirstFreePg. 1414 */ 1415 chunk->c_Next = z->z_PageAry[pgno]; 1416 z->z_PageAry[pgno] = chunk; 1417 if (z->z_FirstFreePg > pgno) 1418 z->z_FirstFreePg = pgno; 1419 1420 /* 1421 * Bump the number of free chunks. If it becomes non-zero the zone 1422 * must be added back onto the appropriate list. 1423 */ 1424 if (z->z_NFree++ == 0) { 1425 z->z_Next = slgd->ZoneAry[z->z_ZoneIndex]; 1426 slgd->ZoneAry[z->z_ZoneIndex] = z; 1427 } 1428 1429 /* 1430 * If the zone becomes totally free then release it. 1431 */ 1432 if (z->z_NFree == z->z_NMax) { 1433 slzone_t *pz; 1434 1435 pz = &slgd->ZoneAry[z->z_ZoneIndex]; 1436 while (z != *pz) 1437 pz = &(*pz)->z_Next; 1438 *pz = z->z_Next; 1439 z->z_Magic = -1; 1440 z->z_Next = NULL; 1441 zone_free(z); 1442 /* slgd lock released */ 1443 return; 1444 } 1445 slgd_unlock(slgd); 1446 } 1447 1448 /* 1449 * Allocate and return a magazine. NULL is returned and *burst is adjusted 1450 * if the magazine is empty. 1451 */ 1452 static __inline void * 1453 magazine_alloc(struct magazine *mp, int *burst) 1454 { 1455 void *obj; 1456 1457 if (mp == NULL) 1458 return(NULL); 1459 if (MAGAZINE_NOTEMPTY(mp)) { 1460 obj = mp->objects[--mp->rounds]; 1461 return(obj); 1462 } 1463 1464 /* 1465 * Return burst factor to caller along with NULL 1466 */ 1467 if ((mp->flags & M_BURST) && (burst != NULL)) { 1468 *burst = mp->burst_factor; 1469 } 1470 /* Reduce burst factor by NSCALE; if it hits 1, disable BURST */ 1471 if ((mp->flags & M_BURST) && (mp->flags & M_BURST_EARLY) && 1472 (burst != NULL)) { 1473 mp->burst_factor -= M_BURST_NSCALE; 1474 if (mp->burst_factor <= 1) { 1475 mp->burst_factor = 1; 1476 mp->flags &= ~(M_BURST); 1477 mp->flags &= ~(M_BURST_EARLY); 1478 } 1479 } 1480 return (NULL); 1481 } 1482 1483 static __inline int 1484 magazine_free(struct magazine *mp, void *p) 1485 { 1486 if (mp != NULL && MAGAZINE_NOTFULL(mp)) { 1487 mp->objects[mp->rounds++] = p; 1488 return 0; 1489 } 1490 1491 return -1; 1492 } 1493 1494 static void * 1495 mtmagazine_alloc(int zi) 1496 { 1497 thr_mags *tp; 1498 struct magazine *mp, *emptymag; 1499 magazine_depot *d; 1500 void *obj; 1501 1502 /* 1503 * Do not try to access per-thread magazines while the mtmagazine 1504 * is being initialized or destroyed. 1505 */ 1506 tp = &thread_mags; 1507 if (tp->init < 0) 1508 return(NULL); 1509 1510 /* 1511 * Primary per-thread allocation loop 1512 */ 1513 for (;;) { 1514 /* 1515 * If the loaded magazine has rounds, allocate and return 1516 */ 1517 mp = tp->mags[zi].loaded; 1518 obj = magazine_alloc(mp, NULL); 1519 if (obj) 1520 break; 1521 1522 /* 1523 * If the prev magazine is full, swap with the loaded 1524 * magazine and retry. 1525 */ 1526 mp = tp->mags[zi].prev; 1527 if (mp && MAGAZINE_FULL(mp)) { 1528 MASSERT(mp->rounds != 0); 1529 swap_mags(&tp->mags[zi]); /* prev now empty */ 1530 continue; 1531 } 1532 1533 /* 1534 * Try to get a full magazine from the depot. Cycle 1535 * through depot(full)->loaded->prev->depot(empty). 1536 * Retry if a full magazine was available from the depot. 1537 * 1538 * Return NULL (caller will fall through) if no magazines 1539 * can be found anywhere. 1540 */ 1541 d = &depots[zi]; 1542 depot_lock(d); 1543 emptymag = tp->mags[zi].prev; 1544 if (emptymag) 1545 SLIST_INSERT_HEAD(&d->empty, emptymag, nextmagazine); 1546 tp->mags[zi].prev = tp->mags[zi].loaded; 1547 mp = SLIST_FIRST(&d->full); /* loaded magazine */ 1548 tp->mags[zi].loaded = mp; 1549 if (mp) { 1550 SLIST_REMOVE_HEAD(&d->full, nextmagazine); 1551 MASSERT(MAGAZINE_NOTEMPTY(mp)); 1552 depot_unlock(d); 1553 continue; 1554 } 1555 depot_unlock(d); 1556 break; 1557 } 1558 1559 return (obj); 1560 } 1561 1562 static int 1563 mtmagazine_free(int zi, void *ptr) 1564 { 1565 thr_mags *tp; 1566 struct magazine *mp, *loadedmag; 1567 magazine_depot *d; 1568 int rc = -1; 1569 1570 /* 1571 * Do not try to access per-thread magazines while the mtmagazine 1572 * is being initialized or destroyed. 1573 */ 1574 tp = &thread_mags; 1575 if (tp->init < 0) 1576 return(-1); 1577 1578 /* 1579 * Primary per-thread freeing loop 1580 */ 1581 for (;;) { 1582 /* 1583 * Make sure a new magazine is available in case we have 1584 * to use it. Staging the newmag allows us to avoid 1585 * some locking/reentrancy complexity. 1586 * 1587 * Temporarily disable the per-thread caches for this 1588 * allocation to avoid reentrancy and/or to avoid a 1589 * stack overflow if the [zi] happens to be the same that 1590 * would be used to allocate the new magazine. 1591 */ 1592 if (tp->newmag == NULL) { 1593 tp->init = -1; 1594 tp->newmag = _slaballoc(sizeof(struct magazine), 1595 SAFLAG_ZERO); 1596 tp->init = 1; 1597 if (tp->newmag == NULL) { 1598 rc = -1; 1599 break; 1600 } 1601 } 1602 1603 /* 1604 * If the loaded magazine has space, free directly to it 1605 */ 1606 rc = magazine_free(tp->mags[zi].loaded, ptr); 1607 if (rc == 0) 1608 break; 1609 1610 /* 1611 * If the prev magazine is empty, swap with the loaded 1612 * magazine and retry. 1613 */ 1614 mp = tp->mags[zi].prev; 1615 if (mp && MAGAZINE_EMPTY(mp)) { 1616 MASSERT(mp->rounds == 0); 1617 swap_mags(&tp->mags[zi]); /* prev now full */ 1618 continue; 1619 } 1620 1621 /* 1622 * Try to get an empty magazine from the depot. Cycle 1623 * through depot(empty)->loaded->prev->depot(full). 1624 * Retry if an empty magazine was available from the depot. 1625 */ 1626 d = &depots[zi]; 1627 depot_lock(d); 1628 1629 if ((loadedmag = tp->mags[zi].prev) != NULL) 1630 SLIST_INSERT_HEAD(&d->full, loadedmag, nextmagazine); 1631 tp->mags[zi].prev = tp->mags[zi].loaded; 1632 mp = SLIST_FIRST(&d->empty); 1633 if (mp) { 1634 tp->mags[zi].loaded = mp; 1635 SLIST_REMOVE_HEAD(&d->empty, nextmagazine); 1636 MASSERT(MAGAZINE_NOTFULL(mp)); 1637 } else { 1638 mp = tp->newmag; 1639 tp->newmag = NULL; 1640 mp->capacity = M_MAX_ROUNDS; 1641 mp->rounds = 0; 1642 mp->flags = 0; 1643 tp->mags[zi].loaded = mp; 1644 } 1645 depot_unlock(d); 1646 } 1647 1648 return rc; 1649 } 1650 1651 static void 1652 mtmagazine_init(void) 1653 { 1654 int error; 1655 1656 error = pthread_key_create(&thread_mags_key, mtmagazine_destructor); 1657 if (error) 1658 abort(); 1659 } 1660 1661 /* 1662 * This function is only used by the thread exit destructor 1663 */ 1664 static void 1665 mtmagazine_drain(struct magazine *mp) 1666 { 1667 void *obj; 1668 1669 while (MAGAZINE_NOTEMPTY(mp)) { 1670 obj = magazine_alloc(mp, NULL); 1671 _slabfree(obj, 0, NULL); 1672 } 1673 } 1674 1675 /* 1676 * mtmagazine_destructor() 1677 * 1678 * When a thread exits, we reclaim all its resources; all its magazines are 1679 * drained and the structures are freed. 1680 * 1681 * WARNING! The destructor can be called multiple times if the larger user 1682 * program has its own destructors which run after ours which 1683 * allocate or free memory. 1684 */ 1685 static void 1686 mtmagazine_destructor(void *thrp) 1687 { 1688 thr_mags *tp = thrp; 1689 struct magazine *mp; 1690 int i; 1691 1692 /* 1693 * Prevent further use of mtmagazines while we are destructing 1694 * them, as well as for any destructors which are run after us 1695 * prior to the thread actually being destroyed. 1696 */ 1697 tp->init = -1; 1698 1699 for (i = 0; i < NZONES; i++) { 1700 mp = tp->mags[i].loaded; 1701 tp->mags[i].loaded = NULL; 1702 if (mp) { 1703 if (MAGAZINE_NOTEMPTY(mp)) 1704 mtmagazine_drain(mp); 1705 _slabfree(mp, 0, NULL); 1706 } 1707 1708 mp = tp->mags[i].prev; 1709 tp->mags[i].prev = NULL; 1710 if (mp) { 1711 if (MAGAZINE_NOTEMPTY(mp)) 1712 mtmagazine_drain(mp); 1713 _slabfree(mp, 0, NULL); 1714 } 1715 } 1716 1717 if (tp->newmag) { 1718 mp = tp->newmag; 1719 tp->newmag = NULL; 1720 _slabfree(mp, 0, NULL); 1721 } 1722 } 1723 1724 /* 1725 * zone_alloc() 1726 * 1727 * Attempt to allocate a zone from the zone magazine; the zone magazine has 1728 * M_BURST_EARLY enabled, so honor the burst request from the magazine. 1729 */ 1730 static slzone_t 1731 zone_alloc(int flags) 1732 { 1733 slglobaldata_t slgd = &SLGlobalData; 1734 int burst = 1; 1735 int i, j; 1736 slzone_t z; 1737 1738 zone_magazine_lock(); 1739 slgd_unlock(slgd); 1740 1741 z = magazine_alloc(&zone_magazine, &burst); 1742 if (z == NULL && burst == 1) { 1743 zone_magazine_unlock(); 1744 z = _vmem_alloc(ZoneSize * burst, ZoneSize, flags); 1745 } else if (z == NULL) { 1746 z = _vmem_alloc(ZoneSize * burst, ZoneSize, flags); 1747 if (z) { 1748 for (i = 1; i < burst; i++) { 1749 j = magazine_free(&zone_magazine, 1750 (char *) z + (ZoneSize * i)); 1751 MASSERT(j == 0); 1752 } 1753 } 1754 zone_magazine_unlock(); 1755 } else { 1756 z->z_Flags |= SLZF_UNOTZEROD; 1757 zone_magazine_unlock(); 1758 } 1759 slgd_lock(slgd); 1760 return z; 1761 } 1762 1763 /* 1764 * zone_free() 1765 * 1766 * Release a zone and unlock the slgd lock. 1767 */ 1768 static void 1769 zone_free(void *z) 1770 { 1771 slglobaldata_t slgd = &SLGlobalData; 1772 void *excess[M_ZONE_ROUNDS - M_LOW_ROUNDS] = {}; 1773 int i, j; 1774 1775 zone_magazine_lock(); 1776 slgd_unlock(slgd); 1777 1778 bzero(z, sizeof(struct slzone)); 1779 1780 if (opt_madvise) 1781 madvise(z, ZoneSize, MADV_FREE); 1782 1783 i = magazine_free(&zone_magazine, z); 1784 1785 /* 1786 * If we failed to free, collect excess magazines; release the zone 1787 * magazine lock, and then free to the system via _vmem_free. Re-enable 1788 * BURST mode for the magazine. 1789 */ 1790 if (i == -1) { 1791 j = zone_magazine.rounds - zone_magazine.low_factor; 1792 for (i = 0; i < j; i++) { 1793 excess[i] = magazine_alloc(&zone_magazine, NULL); 1794 MASSERT(excess[i] != NULL); 1795 } 1796 1797 zone_magazine_unlock(); 1798 1799 for (i = 0; i < j; i++) 1800 _vmem_free(excess[i], ZoneSize); 1801 1802 _vmem_free(z, ZoneSize); 1803 } else { 1804 zone_magazine_unlock(); 1805 } 1806 } 1807 1808 /* 1809 * _vmem_alloc() 1810 * 1811 * Directly map memory in PAGE_SIZE'd chunks with the specified 1812 * alignment. 1813 * 1814 * Alignment must be a multiple of PAGE_SIZE. 1815 * 1816 * Size must be >= alignment. 1817 */ 1818 static void * 1819 _vmem_alloc(size_t size, size_t align, int flags) 1820 { 1821 char *addr; 1822 char *save; 1823 size_t excess; 1824 1825 /* 1826 * Map anonymous private memory. 1827 */ 1828 addr = mmap(NULL, size, PROT_READ|PROT_WRITE, 1829 MAP_PRIVATE|MAP_ANON, -1, 0); 1830 if (addr == MAP_FAILED) 1831 return(NULL); 1832 1833 /* 1834 * Check alignment. The misaligned offset is also the excess 1835 * amount. If misaligned unmap the excess so we have a chance of 1836 * mapping at the next alignment point and recursively try again. 1837 * 1838 * BBBBBBBBBBB BBBBBBBBBBB BBBBBBBBBBB block alignment 1839 * aaaaaaaaa aaaaaaaaaaa aa mis-aligned allocation 1840 * xxxxxxxxx final excess calculation 1841 * ^ returned address 1842 */ 1843 excess = (uintptr_t)addr & (align - 1); 1844 1845 if (excess) { 1846 excess = align - excess; 1847 save = addr; 1848 1849 munmap(save + excess, size - excess); 1850 addr = _vmem_alloc(size, align, flags); 1851 munmap(save, excess); 1852 } 1853 return((void *)addr); 1854 } 1855 1856 /* 1857 * _vmem_free() 1858 * 1859 * Free a chunk of memory allocated with _vmem_alloc() 1860 */ 1861 static void 1862 _vmem_free(void *ptr, size_t size) 1863 { 1864 munmap(ptr, size); 1865 } 1866 1867 /* 1868 * Panic on fatal conditions 1869 */ 1870 static void 1871 _mpanic(const char *ctl, ...) 1872 { 1873 va_list va; 1874 1875 if (malloc_panic == 0) { 1876 malloc_panic = 1; 1877 va_start(va, ctl); 1878 vfprintf(stderr, ctl, va); 1879 fprintf(stderr, "\n"); 1880 fflush(stderr); 1881 va_end(va); 1882 } 1883 abort(); 1884 } 1885 1886 __weak_reference(__malloc, malloc); 1887 __weak_reference(__calloc, calloc); 1888 __weak_reference(__posix_memalign, posix_memalign); 1889 __weak_reference(__realloc, realloc); 1890 __weak_reference(__free, free); 1891