1 /*- 2 * Copyright (c) 1983 Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 /* 35 * malloc.c (Caltech) 2/21/82 36 * Chris Kingsley, kingsley@cit-20. 37 * 38 * This is a very fast storage allocator. It allocates blocks of a small 39 * number of different sizes, and keeps free lists of each size. Blocks that 40 * don't exactly fit are passed up to the next larger size. In this 41 * implementation, the available sizes are 2^n-4 (or 2^n-10) bytes long. 42 * This is designed for use in a virtual memory environment. 43 */ 44 45 #include <sys/types.h> 46 #include <paths.h> 47 #include <stdarg.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <unistd.h> 52 #include <sys/param.h> 53 #include <sys/mman.h> 54 #include "rtld_printf.h" 55 #ifndef BSD 56 #define MAP_COPY MAP_PRIVATE 57 #define MAP_FILE 0 58 #define MAP_ANON 0 59 #endif 60 61 #ifndef BSD /* Need do better than this */ 62 #define NEED_DEV_ZERO 1 63 #endif 64 65 static void morecore(); 66 static int findbucket(); 67 68 /* 69 * Pre-allocate mmap'ed pages 70 */ 71 #define NPOOLPAGES (32*1024/pagesz) 72 static caddr_t pagepool_start, pagepool_end; 73 static int morepages(); 74 75 /* 76 * The overhead on a block is at least 4 bytes. When free, this space 77 * contains a pointer to the next free block, and the bottom two bits must 78 * be zero. When in use, the first byte is set to MAGIC, and the second 79 * byte is the size index. The remaining bytes are for alignment. 80 * If range checking is enabled then a second word holds the size of the 81 * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC). 82 * The order of elements is critical: ov_magic must overlay the low order 83 * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern. 84 */ 85 union overhead { 86 union overhead *ov_next; /* when free */ 87 struct { 88 u_char ovu_magic; /* magic number */ 89 u_char ovu_index; /* bucket # */ 90 #ifdef RCHECK 91 u_short ovu_rmagic; /* range magic number */ 92 u_int ovu_size; /* actual block size */ 93 #endif 94 } ovu; 95 #define ov_magic ovu.ovu_magic 96 #define ov_index ovu.ovu_index 97 #define ov_rmagic ovu.ovu_rmagic 98 #define ov_size ovu.ovu_size 99 }; 100 101 #define MAGIC 0xef /* magic # on accounting info */ 102 #define RMAGIC 0x5555 /* magic # on range info */ 103 104 #ifdef RCHECK 105 #define RSLOP sizeof (u_short) 106 #else 107 #define RSLOP 0 108 #endif 109 110 /* 111 * nextf[i] is the pointer to the next free block of size 2^(i+3). The 112 * smallest allocatable block is 8 bytes. The overhead information 113 * precedes the data area returned to the user. 114 */ 115 #define NBUCKETS 30 116 static union overhead *nextf[NBUCKETS]; 117 118 static int pagesz; /* page size */ 119 static int pagebucket; /* page size bucket */ 120 121 #ifdef MSTATS 122 /* 123 * nmalloc[i] is the difference between the number of mallocs and frees 124 * for a given block size. 125 */ 126 static u_int nmalloc[NBUCKETS]; 127 #include <stdio.h> 128 #endif 129 130 #if defined(MALLOC_DEBUG) || defined(RCHECK) 131 #define ASSERT(p) if (!(p)) botch("p") 132 #include <stdio.h> 133 static void 134 botch(s) 135 char *s; 136 { 137 fprintf(stderr, "\r\nassertion botched: %s\r\n", s); 138 (void) fflush(stderr); /* just in case user buffered it */ 139 abort(); 140 } 141 #else 142 #define ASSERT(p) 143 #endif 144 145 /* Debugging stuff */ 146 #define TRACE() rtld_printf("TRACE %s:%d\n", __FILE__, __LINE__) 147 148 void * 149 malloc(nbytes) 150 size_t nbytes; 151 { 152 register union overhead *op; 153 register int bucket; 154 register long n; 155 register unsigned amt; 156 157 /* 158 * First time malloc is called, setup page size and 159 * align break pointer so all data will be page aligned. 160 */ 161 if (pagesz == 0) { 162 pagesz = n = getpagesize(); 163 if (morepages(NPOOLPAGES) == 0) 164 return NULL; 165 op = (union overhead *)(pagepool_start); 166 n = n - sizeof (*op) - ((long)op & (n - 1)); 167 if (n < 0) 168 n += pagesz; 169 if (n) { 170 pagepool_start += n; 171 } 172 bucket = 0; 173 amt = 8; 174 while ((unsigned)pagesz > amt) { 175 amt <<= 1; 176 bucket++; 177 } 178 pagebucket = bucket; 179 } 180 /* 181 * Convert amount of memory requested into closest block size 182 * stored in hash buckets which satisfies request. 183 * Account for space used per block for accounting. 184 */ 185 if (nbytes <= (unsigned long)(n = pagesz - sizeof (*op) - RSLOP)) { 186 #ifndef RCHECK 187 amt = 8; /* size of first bucket */ 188 bucket = 0; 189 #else 190 amt = 16; /* size of first bucket */ 191 bucket = 1; 192 #endif 193 n = -(sizeof (*op) + RSLOP); 194 } else { 195 amt = pagesz; 196 bucket = pagebucket; 197 } 198 while (nbytes > amt + n) { 199 amt <<= 1; 200 if (amt == 0) 201 return (NULL); 202 bucket++; 203 } 204 /* 205 * If nothing in hash bucket right now, 206 * request more memory from the system. 207 */ 208 if ((op = nextf[bucket]) == NULL) { 209 morecore(bucket); 210 if ((op = nextf[bucket]) == NULL) 211 return (NULL); 212 } 213 /* remove from linked list */ 214 nextf[bucket] = op->ov_next; 215 op->ov_magic = MAGIC; 216 op->ov_index = bucket; 217 #ifdef MSTATS 218 nmalloc[bucket]++; 219 #endif 220 #ifdef RCHECK 221 /* 222 * Record allocated size of block and 223 * bound space with magic numbers. 224 */ 225 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1); 226 op->ov_rmagic = RMAGIC; 227 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC; 228 #endif 229 return ((char *)(op + 1)); 230 } 231 232 /* 233 * Used by rtld.c, if we don't override it here the calloc from 234 * libc may try to pull in the malloc/realloc/free from libc too. 235 */ 236 void * 237 calloc(size_t num, size_t size) 238 { 239 void *p; 240 241 size *= num; 242 if ((p = malloc(size)) != NULL) 243 bzero(p, size); 244 return(p); 245 } 246 247 /* 248 * Allocate more memory to the indicated bucket. 249 */ 250 static void 251 morecore(bucket) 252 int bucket; 253 { 254 register union overhead *op; 255 register int sz; /* size of desired block */ 256 int amt; /* amount to allocate */ 257 int nblks; /* how many blocks we get */ 258 259 /* 260 * sbrk_size <= 0 only for big, FLUFFY, requests (about 261 * 2^30 bytes on a VAX, I think) or for a negative arg. 262 */ 263 sz = 1 << (bucket + 3); 264 #ifdef MALLOC_DEBUG 265 ASSERT(sz > 0); 266 #else 267 if (sz <= 0) 268 return; 269 #endif 270 if (sz < pagesz) { 271 amt = pagesz; 272 nblks = amt / sz; 273 } else { 274 amt = sz + pagesz; 275 nblks = 1; 276 } 277 if (amt > pagepool_end - pagepool_start) 278 if (morepages(amt/pagesz + NPOOLPAGES) == 0) 279 return; 280 op = (union overhead *)pagepool_start; 281 pagepool_start += amt; 282 283 /* 284 * Add new memory allocated to that on 285 * free list for this hash bucket. 286 */ 287 nextf[bucket] = op; 288 while (--nblks > 0) { 289 op->ov_next = (union overhead *)((caddr_t)op + sz); 290 op = (union overhead *)((caddr_t)op + sz); 291 } 292 } 293 294 void 295 free(cp) 296 void *cp; 297 { 298 register int size; 299 register union overhead *op; 300 301 if (cp == NULL) 302 return; 303 op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); 304 #ifdef MALLOC_DEBUG 305 ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */ 306 #else 307 if (op->ov_magic != MAGIC) 308 return; /* sanity */ 309 #endif 310 #ifdef RCHECK 311 ASSERT(op->ov_rmagic == RMAGIC); 312 ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC); 313 #endif 314 size = op->ov_index; 315 ASSERT(size < NBUCKETS); 316 op->ov_next = nextf[size]; /* also clobbers ov_magic */ 317 nextf[size] = op; 318 #ifdef MSTATS 319 nmalloc[size]--; 320 #endif 321 } 322 323 /* 324 * When a program attempts "storage compaction" as mentioned in the 325 * old malloc man page, it realloc's an already freed block. Usually 326 * this is the last block it freed; occasionally it might be farther 327 * back. We have to search all the free lists for the block in order 328 * to determine its bucket: 1st we make one pass thru the lists 329 * checking only the first block in each; if that fails we search 330 * ``realloc_srchlen'' blocks in each list for a match (the variable 331 * is extern so the caller can modify it). If that fails we just copy 332 * however many bytes was given to realloc() and hope it's not huge. 333 */ 334 int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ 335 336 void * 337 realloc(cp, nbytes) 338 void *cp; 339 size_t nbytes; 340 { 341 register u_int onb; 342 register int i; 343 union overhead *op; 344 char *res; 345 int was_alloced = 0; 346 347 if (cp == NULL) 348 return (malloc(nbytes)); 349 op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); 350 if (op->ov_magic == MAGIC) { 351 was_alloced++; 352 i = op->ov_index; 353 } else { 354 /* 355 * Already free, doing "compaction". 356 * 357 * Search for the old block of memory on the 358 * free list. First, check the most common 359 * case (last element free'd), then (this failing) 360 * the last ``realloc_srchlen'' items free'd. 361 * If all lookups fail, then assume the size of 362 * the memory block being realloc'd is the 363 * largest possible (so that all "nbytes" of new 364 * memory are copied into). Note that this could cause 365 * a memory fault if the old area was tiny, and the moon 366 * is gibbous. However, that is very unlikely. 367 */ 368 if ((i = findbucket(op, 1)) < 0 && 369 (i = findbucket(op, realloc_srchlen)) < 0) 370 i = NBUCKETS; 371 } 372 onb = 1 << (i + 3); 373 if (onb < (u_int)pagesz) 374 onb -= sizeof (*op) + RSLOP; 375 else 376 onb += pagesz - sizeof (*op) - RSLOP; 377 /* avoid the copy if same size block */ 378 if (was_alloced) { 379 if (i) { 380 i = 1 << (i + 2); 381 if (i < pagesz) 382 i -= sizeof (*op) + RSLOP; 383 else 384 i += pagesz - sizeof (*op) - RSLOP; 385 } 386 if (nbytes <= onb && nbytes > (size_t)i) { 387 #ifdef RCHECK 388 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1); 389 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC; 390 #endif 391 return(cp); 392 } else 393 free(cp); 394 } 395 if ((res = malloc(nbytes)) == NULL) 396 return (NULL); 397 if (cp != res) /* common optimization if "compacting" */ 398 bcopy(cp, res, (nbytes < onb) ? nbytes : onb); 399 return (res); 400 } 401 402 /* 403 * Search ``srchlen'' elements of each free list for a block whose 404 * header starts at ``freep''. If srchlen is -1 search the whole list. 405 * Return bucket number, or -1 if not found. 406 */ 407 static int 408 findbucket(freep, srchlen) 409 union overhead *freep; 410 int srchlen; 411 { 412 register union overhead *p; 413 register int i, j; 414 415 for (i = 0; i < NBUCKETS; i++) { 416 j = 0; 417 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) { 418 if (p == freep) 419 return (i); 420 j++; 421 } 422 } 423 return (-1); 424 } 425 426 #ifdef MSTATS 427 /* 428 * mstats - print out statistics about malloc 429 * 430 * Prints two lines of numbers, one showing the length of the free list 431 * for each size category, the second showing the number of mallocs - 432 * frees for each size category. 433 */ 434 mstats(s) 435 char *s; 436 { 437 register int i, j; 438 register union overhead *p; 439 int totfree = 0, 440 totused = 0; 441 442 fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s); 443 for (i = 0; i < NBUCKETS; i++) { 444 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) 445 ; 446 fprintf(stderr, " %d", j); 447 totfree += j * (1 << (i + 3)); 448 } 449 fprintf(stderr, "\nused:\t"); 450 for (i = 0; i < NBUCKETS; i++) { 451 fprintf(stderr, " %d", nmalloc[i]); 452 totused += nmalloc[i] * (1 << (i + 3)); 453 } 454 fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n", 455 totused, totfree); 456 } 457 #endif 458 459 460 static int 461 morepages(n) 462 int n; 463 { 464 int fd = -1; 465 int offset; 466 467 #ifdef NEED_DEV_ZERO 468 fd = open(_PATH_DEVZERO, O_RDWR, 0); 469 if (fd == -1) 470 perror(_PATH_DEVZERO); 471 #endif 472 473 if (pagepool_end - pagepool_start > pagesz) { 474 caddr_t addr = (caddr_t) 475 (((long)pagepool_start + pagesz - 1) & ~(pagesz - 1)); 476 if (munmap(addr, pagepool_end - addr) != 0) 477 rtld_fdprintf(STDERR_FILENO, "morepages: munmap %p", 478 addr); 479 } 480 481 offset = (long)pagepool_start - ((long)pagepool_start & ~(pagesz - 1)); 482 483 if ((pagepool_start = mmap(0, n * pagesz, 484 PROT_READ|PROT_WRITE, 485 MAP_ANON|MAP_COPY, fd, 0)) == (caddr_t)-1) { 486 rtld_printf("Cannot map anonymous memory\n"); 487 return 0; 488 } 489 pagepool_end = pagepool_start + n * pagesz; 490 pagepool_start += offset; 491 492 #ifdef NEED_DEV_ZERO 493 close(fd); 494 #endif 495 return n; 496 } 497