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. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30#if defined(LIBC_SCCS) && !defined(lint) 31/*static char *sccsid = "from: @(#)malloc.c 5.11 (Berkeley) 2/23/91";*/ 32static char *rcsid = "$FreeBSD$"; 33#endif /* LIBC_SCCS and not lint */ 34 35/* 36 * malloc.c (Caltech) 2/21/82 37 * Chris Kingsley, kingsley@cit-20. 38 * 39 * This is a very fast storage allocator. It allocates blocks of a small 40 * number of different sizes, and keeps free lists of each size. Blocks that 41 * don't exactly fit are passed up to the next larger size. In this 42 * implementation, the available sizes are 2^n-4 (or 2^n-10) bytes long. 43 * This is designed for use in a virtual memory environment. 44 */ 45 46#include <sys/types.h> 47#include <sys/sysctl.h> 48#include <stdarg.h> 49#include <stddef.h> 50#include <stdio.h> 51#include <stdlib.h> 52#include <string.h> 53#include <unistd.h> 54#include <sys/param.h> 55#include <sys/mman.h> 56#include "rtld_printf.h" 57 58static void morecore(); 59static int findbucket(); 60 61/* 62 * Pre-allocate mmap'ed pages 63 */ 64#define NPOOLPAGES (32*1024/pagesz) 65static caddr_t pagepool_start, pagepool_end; 66static int morepages(); 67 68/* 69 * The overhead on a block is at least 4 bytes. When free, this space 70 * contains a pointer to the next free block, and the bottom two bits must 71 * be zero. When in use, the first byte is set to MAGIC, and the second 72 * byte is the size index. The remaining bytes are for alignment. 73 * If range checking is enabled then a second word holds the size of the 74 * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC). 75 * The order of elements is critical: ov_magic must overlay the low order 76 * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern. 77 */ 78union overhead { 79 union overhead *ov_next; /* when free */ 80 struct { 81 u_char ovu_magic; /* magic number */ 82 u_char ovu_index; /* bucket # */ 83#ifdef RCHECK 84 u_short ovu_rmagic; /* range magic number */ 85 u_int ovu_size; /* actual block size */ 86#endif 87 } ovu; 88#define ov_magic ovu.ovu_magic 89#define ov_index ovu.ovu_index 90#define ov_rmagic ovu.ovu_rmagic 91#define ov_size ovu.ovu_size 92}; 93 94#define MAGIC 0xef /* magic # on accounting info */ 95#define RMAGIC 0x5555 /* magic # on range info */ 96 97#ifdef RCHECK 98#define RSLOP sizeof (u_short) 99#else 100#define RSLOP 0 101#endif 102 103/* 104 * nextf[i] is the pointer to the next free block of size 2^(i+3). The 105 * smallest allocatable block is 8 bytes. The overhead information 106 * precedes the data area returned to the user. 107 */ 108#define NBUCKETS 30 109static union overhead *nextf[NBUCKETS]; 110 111static int pagesz; /* page size */ 112static int pagebucket; /* page size bucket */ 113 114#ifdef MSTATS 115/* 116 * nmalloc[i] is the difference between the number of mallocs and frees 117 * for a given block size. 118 */ 119static u_int nmalloc[NBUCKETS]; 120#include <stdio.h> 121#endif 122 123#if defined(MALLOC_DEBUG) || defined(RCHECK) 124#define ASSERT(p) if (!(p)) botch("p") 125#include <stdio.h> 126static void 127botch(s) 128 char *s; 129{ 130 fprintf(stderr, "\r\nassertion botched: %s\r\n", s); 131 (void) fflush(stderr); /* just in case user buffered it */ 132 abort(); 133} 134#else 135#define ASSERT(p) 136#endif 137 138/* Debugging stuff */ 139#define TRACE() rtld_printf("TRACE %s:%d\n", __FILE__, __LINE__) 140 141/* 142 * The array of supported page sizes is provided by the user, i.e., the 143 * program that calls this storage allocator. That program must initialize 144 * the array before making its first call to allocate storage. The array 145 * must contain at least one page size. The page sizes must be stored in 146 * increasing order. 147 */ 148extern size_t *pagesizes; 149 150void * 151malloc(nbytes) 152 size_t nbytes; 153{ 154 register union overhead *op; 155 register int bucket; 156 register long n; 157 register unsigned amt; 158 159 /* 160 * First time malloc is called, setup page size and 161 * align break pointer so all data will be page aligned. 162 */ 163 if (pagesz == 0) { 164 pagesz = n = pagesizes[0]; 165 if (morepages(NPOOLPAGES) == 0) 166 return NULL; 167 op = (union overhead *)(pagepool_start); 168 n = n - sizeof (*op) - ((long)op & (n - 1)); 169 if (n < 0) 170 n += pagesz; 171 if (n) { 172 pagepool_start += n; 173 } 174 bucket = 0; 175 amt = 8; 176 while ((unsigned)pagesz > amt) { 177 amt <<= 1; 178 bucket++; 179 } 180 pagebucket = bucket; 181 } 182 /* 183 * Convert amount of memory requested into closest block size 184 * stored in hash buckets which satisfies request. 185 * Account for space used per block for accounting. 186 */ 187 if (nbytes <= (unsigned long)(n = pagesz - sizeof (*op) - RSLOP)) { 188#ifndef RCHECK 189 amt = 8; /* size of first bucket */ 190 bucket = 0; 191#else 192 amt = 16; /* size of first bucket */ 193 bucket = 1; 194#endif 195 n = -(sizeof (*op) + RSLOP); 196 } else { 197 amt = pagesz; 198 bucket = pagebucket; 199 } 200 while (nbytes > amt + n) { 201 amt <<= 1; 202 if (amt == 0) 203 return (NULL); 204 bucket++; 205 } 206 /* 207 * If nothing in hash bucket right now, 208 * request more memory from the system. 209 */ 210 if ((op = nextf[bucket]) == NULL) { 211 morecore(bucket); 212 if ((op = nextf[bucket]) == NULL) 213 return (NULL); 214 } 215 /* remove from linked list */ 216 nextf[bucket] = op->ov_next; 217 op->ov_magic = MAGIC; 218 op->ov_index = bucket; 219#ifdef MSTATS 220 nmalloc[bucket]++; 221#endif 222#ifdef RCHECK 223 /* 224 * Record allocated size of block and 225 * bound space with magic numbers. 226 */ 227 op->ov_size = roundup2(nbytes, RSLOP); 228 op->ov_rmagic = RMAGIC; 229 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC; 230#endif 231 return ((char *)(op + 1)); 232} 233 234void * 235calloc(size_t num, size_t size) 236{ 237 void *ret; 238 239 if (size != 0 && (num * size) / size != num) { 240 /* size_t overflow. */ 241 return (NULL); 242 } 243 244 if ((ret = malloc(num * size)) != NULL) 245 memset(ret, 0, num * size); 246 247 return (ret); 248} 249 250/* 251 * Allocate more memory to the indicated bucket. 252 */ 253static void 254morecore(bucket) 255 int bucket; 256{ 257 register union overhead *op; 258 register int sz; /* size of desired block */ 259 int amt; /* amount to allocate */ 260 int nblks; /* how many blocks we get */ 261 262 /* 263 * sbrk_size <= 0 only for big, FLUFFY, requests (about 264 * 2^30 bytes on a VAX, I think) or for a negative arg. 265 */ 266 sz = 1 << (bucket + 3); 267#ifdef MALLOC_DEBUG 268 ASSERT(sz > 0); 269#else 270 if (sz <= 0) 271 return; 272#endif 273 if (sz < pagesz) { 274 amt = pagesz; 275 nblks = amt / sz; 276 } else { 277 amt = sz + pagesz; 278 nblks = 1; 279 } 280 if (amt > pagepool_end - pagepool_start) 281 if (morepages(amt/pagesz + NPOOLPAGES) == 0) 282 return; 283 op = (union overhead *)pagepool_start; 284 pagepool_start += amt; 285 286 /* 287 * Add new memory allocated to that on 288 * free list for this hash bucket. 289 */ 290 nextf[bucket] = op; 291 while (--nblks > 0) { 292 op->ov_next = (union overhead *)((caddr_t)op + sz); 293 op = (union overhead *)((caddr_t)op + sz); 294 } 295} 296 297void 298free(cp) 299 void *cp; 300{ 301 register int size; 302 register union overhead *op; 303 304 if (cp == NULL) 305 return; 306 op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); 307#ifdef MALLOC_DEBUG 308 ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */ 309#else 310 if (op->ov_magic != MAGIC) 311 return; /* sanity */ 312#endif 313#ifdef RCHECK 314 ASSERT(op->ov_rmagic == RMAGIC); 315 ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC); 316#endif 317 size = op->ov_index; 318 ASSERT(size < NBUCKETS); 319 op->ov_next = nextf[size]; /* also clobbers ov_magic */ 320 nextf[size] = op; 321#ifdef MSTATS 322 nmalloc[size]--; 323#endif 324} 325 326/* 327 * When a program attempts "storage compaction" as mentioned in the 328 * old malloc man page, it realloc's an already freed block. Usually 329 * this is the last block it freed; occasionally it might be farther 330 * back. We have to search all the free lists for the block in order 331 * to determine its bucket: 1st we make one pass through the lists 332 * checking only the first block in each; if that fails we search 333 * ``realloc_srchlen'' blocks in each list for a match (the variable 334 * is extern so the caller can modify it). If that fails we just copy 335 * however many bytes was given to realloc() and hope it's not huge. 336 */ 337int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ 338 339void * 340realloc(cp, nbytes) 341 void *cp; 342 size_t nbytes; 343{ 344 register u_int onb; 345 register int i; 346 union overhead *op; 347 char *res; 348 int was_alloced = 0; 349 350 if (cp == NULL) 351 return (malloc(nbytes)); 352 op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); 353 if (op->ov_magic == MAGIC) { 354 was_alloced++; 355 i = op->ov_index; 356 } else { 357 /* 358 * Already free, doing "compaction". 359 * 360 * Search for the old block of memory on the 361 * free list. First, check the most common 362 * case (last element free'd), then (this failing) 363 * the last ``realloc_srchlen'' items free'd. 364 * If all lookups fail, then assume the size of 365 * the memory block being realloc'd is the 366 * largest possible (so that all "nbytes" of new 367 * memory are copied into). Note that this could cause 368 * a memory fault if the old area was tiny, and the moon 369 * is gibbous. However, that is very unlikely. 370 */ 371 if ((i = findbucket(op, 1)) < 0 && 372 (i = findbucket(op, realloc_srchlen)) < 0) 373 i = NBUCKETS; 374 } 375 onb = 1 << (i + 3); 376 if (onb < (u_int)pagesz) 377 onb -= sizeof (*op) + RSLOP; 378 else 379 onb += pagesz - sizeof (*op) - RSLOP; 380 /* avoid the copy if same size block */ 381 if (was_alloced) { 382 if (i) { 383 i = 1 << (i + 2); 384 if (i < pagesz) 385 i -= sizeof (*op) + RSLOP; 386 else 387 i += pagesz - sizeof (*op) - RSLOP; 388 } 389 if (nbytes <= onb && nbytes > (size_t)i) { 390#ifdef RCHECK 391 op->ov_size = roundup2(nbytes, RSLOP); 392 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC; 393#endif 394 return(cp); 395 } else 396 free(cp); 397 } 398 if ((res = malloc(nbytes)) == NULL) 399 return (NULL); 400 if (cp != res) /* common optimization if "compacting" */ 401 bcopy(cp, res, (nbytes < onb) ? nbytes : onb); 402 return (res); 403} 404 405/* 406 * Search ``srchlen'' elements of each free list for a block whose 407 * header starts at ``freep''. If srchlen is -1 search the whole list. 408 * Return bucket number, or -1 if not found. 409 */ 410static int 411findbucket(freep, srchlen) 412 union overhead *freep; 413 int srchlen; 414{ 415 register union overhead *p; 416 register int i, j; 417 418 for (i = 0; i < NBUCKETS; i++) { 419 j = 0; 420 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) { 421 if (p == freep) 422 return (i); 423 j++; 424 } 425 } 426 return (-1); 427} 428 429#ifdef MSTATS 430/* 431 * mstats - print out statistics about malloc 432 * 433 * Prints two lines of numbers, one showing the length of the free list 434 * for each size category, the second showing the number of mallocs - 435 * frees for each size category. 436 */ 437mstats(s) 438 char *s; 439{ 440 register int i, j; 441 register union overhead *p; 442 int totfree = 0, 443 totused = 0; 444 445 fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s); 446 for (i = 0; i < NBUCKETS; i++) { 447 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) 448 ; 449 fprintf(stderr, " %d", j); 450 totfree += j * (1 << (i + 3)); 451 } 452 fprintf(stderr, "\nused:\t"); 453 for (i = 0; i < NBUCKETS; i++) { 454 fprintf(stderr, " %d", nmalloc[i]); 455 totused += nmalloc[i] * (1 << (i + 3)); 456 } 457 fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n", 458 totused, totfree); 459} 460#endif 461 462 463static int 464morepages(n) 465int n; 466{ 467 int fd = -1; 468 int offset; 469 470 if (pagepool_end - pagepool_start > pagesz) { 471 caddr_t addr = (caddr_t) 472 (((long)pagepool_start + pagesz - 1) & ~(pagesz - 1)); 473 if (munmap(addr, pagepool_end - addr) != 0) 474 rtld_fdprintf(STDERR_FILENO, "morepages: munmap %p", 475 addr); 476 } 477 478 offset = (long)pagepool_start - ((long)pagepool_start & ~(pagesz - 1)); 479 480 if ((pagepool_start = mmap(0, n * pagesz, 481 PROT_READ|PROT_WRITE, 482 MAP_ANON|MAP_COPY, fd, 0)) == (caddr_t)-1) { 483 rtld_printf("Cannot map anonymous memory\n"); 484 return 0; 485 } 486 pagepool_end = pagepool_start + n * pagesz; 487 pagepool_start += offset; 488 489 return n; 490} 491