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#if defined(LIBC_SCCS) && !defined(lint) 35/*static char *sccsid = "from: @(#)malloc.c 5.11 (Berkeley) 2/23/91";*/ 36static char *rcsid = "$FreeBSD$"; 37#endif /* LIBC_SCCS and not lint */ 38 39/* 40 * malloc.c (Caltech) 2/21/82 41 * Chris Kingsley, kingsley@cit-20. 42 * 43 * This is a very fast storage allocator. It allocates blocks of a small 44 * number of different sizes, and keeps free lists of each size. Blocks that 45 * don't exactly fit are passed up to the next larger size. In this 46 * implementation, the available sizes are 2^n-4 (or 2^n-10) bytes long. 47 * This is designed for use in a virtual memory environment. 48 */ 49 50#include <sys/types.h> 51#include <sys/sysctl.h> 52#include <paths.h> 53#include <stdarg.h> 54#include <stddef.h> 55#include <stdio.h> 56#include <stdlib.h> 57#include <string.h> 58#include <unistd.h> 59#include <sys/param.h> 60#include <sys/mman.h> 61#include "rtld_printf.h" 62 63static void morecore(); 64static int findbucket(); 65 66/* 67 * Pre-allocate mmap'ed pages 68 */ 69#define NPOOLPAGES (32*1024/pagesz) 70static caddr_t pagepool_start, pagepool_end; 71static int morepages(); 72 73/* 74 * The overhead on a block is at least 4 bytes. When free, this space 75 * contains a pointer to the next free block, and the bottom two bits must 76 * be zero. When in use, the first byte is set to MAGIC, and the second 77 * byte is the size index. The remaining bytes are for alignment. 78 * If range checking is enabled then a second word holds the size of the 79 * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC). 80 * The order of elements is critical: ov_magic must overlay the low order 81 * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern. 82 */ 83union overhead { 84 union overhead *ov_next; /* when free */ 85 struct { 86 u_char ovu_magic; /* magic number */ 87 u_char ovu_index; /* bucket # */ 88#ifdef RCHECK 89 u_short ovu_rmagic; /* range magic number */ 90 u_int ovu_size; /* actual block size */ 91#endif 92 } ovu; 93#define ov_magic ovu.ovu_magic 94#define ov_index ovu.ovu_index 95#define ov_rmagic ovu.ovu_rmagic 96#define ov_size ovu.ovu_size 97}; 98 99#define MAGIC 0xef /* magic # on accounting info */ 100#define RMAGIC 0x5555 /* magic # on range info */ 101 102#ifdef RCHECK 103#define RSLOP sizeof (u_short) 104#else 105#define RSLOP 0 106#endif 107 108/* 109 * nextf[i] is the pointer to the next free block of size 2^(i+3). The 110 * smallest allocatable block is 8 bytes. The overhead information 111 * precedes the data area returned to the user. 112 */ 113#define NBUCKETS 30 114static union overhead *nextf[NBUCKETS]; 115 116static int pagesz; /* page size */ 117static int pagebucket; /* page size bucket */ 118 119#ifdef MSTATS 120/* 121 * nmalloc[i] is the difference between the number of mallocs and frees 122 * for a given block size. 123 */ 124static u_int nmalloc[NBUCKETS]; 125#include <stdio.h> 126#endif 127 128#if defined(MALLOC_DEBUG) || defined(RCHECK) 129#define ASSERT(p) if (!(p)) botch("p") 130#include <stdio.h> 131static void 132botch(s) 133 char *s; 134{ 135 fprintf(stderr, "\r\nassertion botched: %s\r\n", s); 136 (void) fflush(stderr); /* just in case user buffered it */ 137 abort(); 138} 139#else 140#define ASSERT(p) 141#endif 142 143/* Debugging stuff */ 144#define TRACE() rtld_printf("TRACE %s:%d\n", __FILE__, __LINE__) 145 146extern int pagesize; 147 148static int 149rtld_getpagesize(void) 150{ 151 int mib[2]; 152 size_t size; 153 154 if (pagesize != 0) 155 return (pagesize); 156 157 mib[0] = CTL_HW; 158 mib[1] = HW_PAGESIZE; 159 size = sizeof(pagesize); 160 if (sysctl(mib, 2, &pagesize, &size, NULL, 0) == -1) 161 return (-1); 162 return (pagesize); 163 164} 165 166void * 167malloc(nbytes) 168 size_t nbytes; 169{ 170 register union overhead *op; 171 register int bucket; 172 register long n; 173 register unsigned amt; 174 175 /* 176 * First time malloc is called, setup page size and 177 * align break pointer so all data will be page aligned. 178 */ 179 if (pagesz == 0) { 180 pagesz = n = rtld_getpagesize(); 181 if (morepages(NPOOLPAGES) == 0) 182 return NULL; 183 op = (union overhead *)(pagepool_start); 184 n = n - sizeof (*op) - ((long)op & (n - 1)); 185 if (n < 0) 186 n += pagesz; 187 if (n) { 188 pagepool_start += n; 189 } 190 bucket = 0; 191 amt = 8; 192 while ((unsigned)pagesz > amt) { 193 amt <<= 1; 194 bucket++; 195 } 196 pagebucket = bucket; 197 } 198 /* 199 * Convert amount of memory requested into closest block size 200 * stored in hash buckets which satisfies request. 201 * Account for space used per block for accounting. 202 */ 203 if (nbytes <= (unsigned long)(n = pagesz - sizeof (*op) - RSLOP)) { 204#ifndef RCHECK 205 amt = 8; /* size of first bucket */ 206 bucket = 0; 207#else 208 amt = 16; /* size of first bucket */ 209 bucket = 1; 210#endif 211 n = -(sizeof (*op) + RSLOP); 212 } else { 213 amt = pagesz; 214 bucket = pagebucket; 215 } 216 while (nbytes > amt + n) { 217 amt <<= 1; 218 if (amt == 0) 219 return (NULL); 220 bucket++; 221 } 222 /* 223 * If nothing in hash bucket right now, 224 * request more memory from the system. 225 */ 226 if ((op = nextf[bucket]) == NULL) { 227 morecore(bucket); 228 if ((op = nextf[bucket]) == NULL) 229 return (NULL); 230 } 231 /* remove from linked list */ 232 nextf[bucket] = op->ov_next; 233 op->ov_magic = MAGIC; 234 op->ov_index = bucket; 235#ifdef MSTATS 236 nmalloc[bucket]++; 237#endif 238#ifdef RCHECK 239 /* 240 * Record allocated size of block and 241 * bound space with magic numbers. 242 */ 243 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1); 244 op->ov_rmagic = RMAGIC; 245 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC; 246#endif 247 return ((char *)(op + 1)); 248} 249 250void * 251calloc(size_t num, size_t size) 252{ 253 void *ret; 254 255 if (size != 0 && (num * size) / size != num) { 256 /* size_t overflow. */ 257 return (NULL); 258 } 259 260 if ((ret = malloc(num * size)) != NULL) 261 memset(ret, 0, num * size); 262 263 return (ret); 264} 265 266/* 267 * Allocate more memory to the indicated bucket. 268 */ 269static void 270morecore(bucket) 271 int bucket; 272{ 273 register union overhead *op; 274 register int sz; /* size of desired block */ 275 int amt; /* amount to allocate */ 276 int nblks; /* how many blocks we get */ 277 278 /* 279 * sbrk_size <= 0 only for big, FLUFFY, requests (about 280 * 2^30 bytes on a VAX, I think) or for a negative arg. 281 */ 282 sz = 1 << (bucket + 3); 283#ifdef MALLOC_DEBUG 284 ASSERT(sz > 0); 285#else 286 if (sz <= 0) 287 return; 288#endif 289 if (sz < pagesz) { 290 amt = pagesz; 291 nblks = amt / sz; 292 } else { 293 amt = sz + pagesz; 294 nblks = 1; 295 } 296 if (amt > pagepool_end - pagepool_start) 297 if (morepages(amt/pagesz + NPOOLPAGES) == 0) 298 return; 299 op = (union overhead *)pagepool_start; 300 pagepool_start += amt; 301 302 /* 303 * Add new memory allocated to that on 304 * free list for this hash bucket. 305 */ 306 nextf[bucket] = op; 307 while (--nblks > 0) { 308 op->ov_next = (union overhead *)((caddr_t)op + sz); 309 op = (union overhead *)((caddr_t)op + sz); 310 } 311} 312 313void 314free(cp) 315 void *cp; 316{ 317 register int size; 318 register union overhead *op; 319 320 if (cp == NULL) 321 return; 322 op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); 323#ifdef MALLOC_DEBUG 324 ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */ 325#else 326 if (op->ov_magic != MAGIC) 327 return; /* sanity */ 328#endif 329#ifdef RCHECK 330 ASSERT(op->ov_rmagic == RMAGIC); 331 ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC); 332#endif 333 size = op->ov_index; 334 ASSERT(size < NBUCKETS); 335 op->ov_next = nextf[size]; /* also clobbers ov_magic */ 336 nextf[size] = op; 337#ifdef MSTATS 338 nmalloc[size]--; 339#endif 340} 341 342/* 343 * When a program attempts "storage compaction" as mentioned in the 344 * old malloc man page, it realloc's an already freed block. Usually 345 * this is the last block it freed; occasionally it might be farther 346 * back. We have to search all the free lists for the block in order 347 * to determine its bucket: 1st we make one pass thru the lists 348 * checking only the first block in each; if that fails we search 349 * ``realloc_srchlen'' blocks in each list for a match (the variable 350 * is extern so the caller can modify it). If that fails we just copy 351 * however many bytes was given to realloc() and hope it's not huge. 352 */ 353int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ 354 355void * 356realloc(cp, nbytes) 357 void *cp; 358 size_t nbytes; 359{ 360 register u_int onb; 361 register int i; 362 union overhead *op; 363 char *res; 364 int was_alloced = 0; 365 366 if (cp == NULL) 367 return (malloc(nbytes)); 368 op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); 369 if (op->ov_magic == MAGIC) { 370 was_alloced++; 371 i = op->ov_index; 372 } else { 373 /* 374 * Already free, doing "compaction". 375 * 376 * Search for the old block of memory on the 377 * free list. First, check the most common 378 * case (last element free'd), then (this failing) 379 * the last ``realloc_srchlen'' items free'd. 380 * If all lookups fail, then assume the size of 381 * the memory block being realloc'd is the 382 * largest possible (so that all "nbytes" of new 383 * memory are copied into). Note that this could cause 384 * a memory fault if the old area was tiny, and the moon 385 * is gibbous. However, that is very unlikely. 386 */ 387 if ((i = findbucket(op, 1)) < 0 && 388 (i = findbucket(op, realloc_srchlen)) < 0) 389 i = NBUCKETS; 390 } 391 onb = 1 << (i + 3); 392 if (onb < (u_int)pagesz) 393 onb -= sizeof (*op) + RSLOP; 394 else 395 onb += pagesz - sizeof (*op) - RSLOP; 396 /* avoid the copy if same size block */ 397 if (was_alloced) { 398 if (i) { 399 i = 1 << (i + 2); 400 if (i < pagesz) 401 i -= sizeof (*op) + RSLOP; 402 else 403 i += pagesz - sizeof (*op) - RSLOP; 404 } 405 if (nbytes <= onb && nbytes > (size_t)i) { 406#ifdef RCHECK 407 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1); 408 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC; 409#endif 410 return(cp); 411 } else 412 free(cp); 413 } 414 if ((res = malloc(nbytes)) == NULL) 415 return (NULL); 416 if (cp != res) /* common optimization if "compacting" */ 417 bcopy(cp, res, (nbytes < onb) ? nbytes : onb); 418 return (res); 419} 420 421/* 422 * Search ``srchlen'' elements of each free list for a block whose 423 * header starts at ``freep''. If srchlen is -1 search the whole list. 424 * Return bucket number, or -1 if not found. 425 */ 426static int 427findbucket(freep, srchlen) 428 union overhead *freep; 429 int srchlen; 430{ 431 register union overhead *p; 432 register int i, j; 433 434 for (i = 0; i < NBUCKETS; i++) { 435 j = 0; 436 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) { 437 if (p == freep) 438 return (i); 439 j++; 440 } 441 } 442 return (-1); 443} 444 445#ifdef MSTATS 446/* 447 * mstats - print out statistics about malloc 448 * 449 * Prints two lines of numbers, one showing the length of the free list 450 * for each size category, the second showing the number of mallocs - 451 * frees for each size category. 452 */ 453mstats(s) 454 char *s; 455{ 456 register int i, j; 457 register union overhead *p; 458 int totfree = 0, 459 totused = 0; 460 461 fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s); 462 for (i = 0; i < NBUCKETS; i++) { 463 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) 464 ; 465 fprintf(stderr, " %d", j); 466 totfree += j * (1 << (i + 3)); 467 } 468 fprintf(stderr, "\nused:\t"); 469 for (i = 0; i < NBUCKETS; i++) { 470 fprintf(stderr, " %d", nmalloc[i]); 471 totused += nmalloc[i] * (1 << (i + 3)); 472 } 473 fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n", 474 totused, totfree); 475} 476#endif 477 478 479static int 480morepages(n) 481int n; 482{ 483 int fd = -1; 484 int offset; 485 486 if (pagepool_end - pagepool_start > pagesz) { 487 caddr_t addr = (caddr_t) 488 (((long)pagepool_start + pagesz - 1) & ~(pagesz - 1)); 489 if (munmap(addr, pagepool_end - addr) != 0) 490 rtld_fdprintf(STDERR_FILENO, "morepages: munmap %p", 491 addr); 492 } 493 494 offset = (long)pagepool_start - ((long)pagepool_start & ~(pagesz - 1)); 495 496 if ((pagepool_start = mmap(0, n * pagesz, 497 PROT_READ|PROT_WRITE, 498 MAP_ANON|MAP_COPY, fd, 0)) == (caddr_t)-1) { 499 rtld_printf("Cannot map anonymous memory\n"); 500 return 0; 501 } 502 pagepool_end = pagepool_start + n * pagesz; 503 pagepool_start += offset; 504 505 return n; 506} 507