2 * Copyright (c) 1983 Regents of the University of California.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
34 #if defined(LIBC_SCCS) && !defined(lint)
35 /*static char *sccsid = "from: @(#)malloc.c 5.11 (Berkeley) 2/23/91";*/
36 static char *rcsid = "$FreeBSD$";
37 #endif /* LIBC_SCCS and not lint */
40 * malloc.c (Caltech) 2/21/82
41 * Chris Kingsley, kingsley@cit-20.
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.
50 #include <sys/types.h>
51 #include <sys/sysctl.h>
59 #include <sys/param.h>
61 #include "rtld_printf.h"
63 static void morecore();
64 static int findbucket();
67 * Pre-allocate mmap'ed pages
69 #define NPOOLPAGES (32*1024/pagesz)
70 static caddr_t pagepool_start, pagepool_end;
71 static int morepages();
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.
84 union overhead *ov_next; /* when free */
86 u_char ovu_magic; /* magic number */
87 u_char ovu_index; /* bucket # */
89 u_short ovu_rmagic; /* range magic number */
90 u_int ovu_size; /* actual block size */
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
99 #define MAGIC 0xef /* magic # on accounting info */
100 #define RMAGIC 0x5555 /* magic # on range info */
103 #define RSLOP sizeof (u_short)
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.
114 static union overhead *nextf[NBUCKETS];
116 static int pagesz; /* page size */
117 static int pagebucket; /* page size bucket */
121 * nmalloc[i] is the difference between the number of mallocs and frees
122 * for a given block size.
124 static u_int nmalloc[NBUCKETS];
128 #if defined(MALLOC_DEBUG) || defined(RCHECK)
129 #define ASSERT(p) if (!(p)) botch("p")
135 fprintf(stderr, "\r\nassertion botched: %s\r\n", s);
136 (void) fflush(stderr); /* just in case user buffered it */
143 /* Debugging stuff */
144 #define TRACE() rtld_printf("TRACE %s:%d\n", __FILE__, __LINE__)
149 rtld_getpagesize(void)
158 mib[1] = HW_PAGESIZE;
159 size = sizeof(pagesize);
160 if (sysctl(mib, 2, &pagesize, &size, NULL, 0) == -1)
170 register union overhead *op;
173 register unsigned amt;
176 * First time malloc is called, setup page size and
177 * align break pointer so all data will be page aligned.
180 pagesz = n = rtld_getpagesize();
181 if (morepages(NPOOLPAGES) == 0)
183 op = (union overhead *)(pagepool_start);
184 n = n - sizeof (*op) - ((long)op & (n - 1));
192 while ((unsigned)pagesz > amt) {
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.
203 if (nbytes <= (unsigned long)(n = pagesz - sizeof (*op) - RSLOP)) {
205 amt = 8; /* size of first bucket */
208 amt = 16; /* size of first bucket */
211 n = -(sizeof (*op) + RSLOP);
216 while (nbytes > amt + n) {
223 * If nothing in hash bucket right now,
224 * request more memory from the system.
226 if ((op = nextf[bucket]) == NULL) {
228 if ((op = nextf[bucket]) == NULL)
231 /* remove from linked list */
232 nextf[bucket] = op->ov_next;
233 op->ov_magic = MAGIC;
234 op->ov_index = bucket;
240 * Record allocated size of block and
241 * bound space with magic numbers.
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;
247 return ((char *)(op + 1));
251 calloc(size_t num, size_t size)
255 if (size != 0 && (num * size) / size != num) {
256 /* size_t overflow. */
260 if ((ret = malloc(num * size)) != NULL)
261 memset(ret, 0, num * size);
267 * Allocate more memory to the indicated bucket.
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 */
279 * sbrk_size <= 0 only for big, FLUFFY, requests (about
280 * 2^30 bytes on a VAX, I think) or for a negative arg.
282 sz = 1 << (bucket + 3);
296 if (amt > pagepool_end - pagepool_start)
297 if (morepages(amt/pagesz + NPOOLPAGES) == 0)
299 op = (union overhead *)pagepool_start;
300 pagepool_start += amt;
303 * Add new memory allocated to that on
304 * free list for this hash bucket.
307 while (--nblks > 0) {
308 op->ov_next = (union overhead *)((caddr_t)op + sz);
309 op = (union overhead *)((caddr_t)op + sz);
318 register union overhead *op;
322 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
324 ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
326 if (op->ov_magic != MAGIC)
330 ASSERT(op->ov_rmagic == RMAGIC);
331 ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
334 ASSERT(size < NBUCKETS);
335 op->ov_next = nextf[size]; /* also clobbers ov_magic */
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.
353 int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
367 return (malloc(nbytes));
368 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
369 if (op->ov_magic == MAGIC) {
374 * Already free, doing "compaction".
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.
387 if ((i = findbucket(op, 1)) < 0 &&
388 (i = findbucket(op, realloc_srchlen)) < 0)
392 if (onb < (u_int)pagesz)
393 onb -= sizeof (*op) + RSLOP;
395 onb += pagesz - sizeof (*op) - RSLOP;
396 /* avoid the copy if same size block */
401 i -= sizeof (*op) + RSLOP;
403 i += pagesz - sizeof (*op) - RSLOP;
405 if (nbytes <= onb && nbytes > (size_t)i) {
407 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
408 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
414 if ((res = malloc(nbytes)) == NULL)
416 if (cp != res) /* common optimization if "compacting" */
417 bcopy(cp, res, (nbytes < onb) ? nbytes : onb);
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.
427 findbucket(freep, srchlen)
428 union overhead *freep;
431 register union overhead *p;
434 for (i = 0; i < NBUCKETS; i++) {
436 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
447 * mstats - print out statistics about malloc
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.
457 register union overhead *p;
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++)
465 fprintf(stderr, " %d", j);
466 totfree += j * (1 << (i + 3));
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));
473 fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
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",
494 offset = (long)pagepool_start - ((long)pagepool_start & ~(pagesz - 1));
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");
502 pagepool_end = pagepool_start + n * pagesz;
503 pagepool_start += offset;