2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1983 Regents of the University of California.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 #if defined(LIBC_SCCS) && !defined(lint)
33 /*static char *sccsid = "from: @(#)malloc.c 5.11 (Berkeley) 2/23/91";*/
34 static char *rcsid = "$FreeBSD$";
35 #endif /* LIBC_SCCS and not lint */
38 * malloc.c (Caltech) 2/21/82
39 * Chris Kingsley, kingsley@cit-20.
41 * This is a very fast storage allocator. It allocates blocks of a small
42 * number of different sizes, and keeps free lists of each size. Blocks that
43 * don't exactly fit are passed up to the next larger size. In this
44 * implementation, the available sizes are 2^n-4 (or 2^n-10) bytes long.
45 * This is designed for use in a virtual memory environment.
48 #include <sys/param.h>
49 #include <sys/sysctl.h>
57 #include "rtld_printf.h"
61 * Pre-allocate mmap'ed pages
63 #define NPOOLPAGES (128*1024/pagesz)
64 static caddr_t pagepool_start, pagepool_end;
67 * The overhead on a block is at least 4 bytes. When free, this space
68 * contains a pointer to the next free block, and the bottom two bits must
69 * be zero. When in use, the first byte is set to MAGIC, and the second
70 * byte is the size index. The remaining bytes are for alignment.
71 * If range checking is enabled then a second word holds the size of the
72 * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
73 * The order of elements is critical: ov_magic must overlay the low order
74 * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
77 union overhead *ov_next; /* when free */
79 u_char ovu_magic; /* magic number */
80 u_char ovu_index; /* bucket # */
82 #define ov_magic ovu.ovu_magic
83 #define ov_index ovu.ovu_index
86 static void morecore(int bucket);
87 static int morepages(int n);
89 #define MAGIC 0xef /* magic # on accounting info */
92 * nextf[i] is the pointer to the next free block of size
93 * (FIRST_BUCKET_SIZE << i). The overhead information precedes the data
94 * area returned to the user.
96 #define FIRST_BUCKET_SIZE 8
98 static union overhead *nextf[NBUCKETS];
100 static int pagesz; /* page size */
103 * The array of supported page sizes is provided by the user, i.e., the
104 * program that calls this storage allocator. That program must initialize
105 * the array before making its first call to allocate storage. The array
106 * must contain at least one page size. The page sizes must be stored in
111 __crt_malloc(size_t nbytes)
118 * First time malloc is called, setup page size.
121 pagesz = pagesizes[0];
123 * Convert amount of memory requested into closest block size
124 * stored in hash buckets which satisfies request.
125 * Account for space used per block for accounting.
127 amt = FIRST_BUCKET_SIZE;
129 while (nbytes > amt - sizeof(*op)) {
132 if (amt == 0 || bucket >= NBUCKETS)
136 * If nothing in hash bucket right now,
137 * request more memory from the system.
139 if ((op = nextf[bucket]) == NULL) {
141 if ((op = nextf[bucket]) == NULL)
144 /* remove from linked list */
145 nextf[bucket] = op->ov_next;
146 op->ov_magic = MAGIC;
147 op->ov_index = bucket;
148 return ((char *)(op + 1));
152 __crt_calloc(size_t num, size_t size)
156 if (size != 0 && (num * size) / size != num) {
157 /* size_t overflow. */
161 if ((ret = __crt_malloc(num * size)) != NULL)
162 memset(ret, 0, num * size);
168 * Allocate more memory to the indicated bucket.
174 int sz; /* size of desired block */
175 int amt; /* amount to allocate */
176 int nblks; /* how many blocks we get */
178 sz = FIRST_BUCKET_SIZE << bucket;
186 if (amt > pagepool_end - pagepool_start)
187 if (morepages(amt/pagesz + NPOOLPAGES) == 0)
189 op = (union overhead *)pagepool_start;
190 pagepool_start += amt;
193 * Add new memory allocated to that on
194 * free list for this hash bucket.
197 while (--nblks > 0) {
198 op->ov_next = (union overhead *)((caddr_t)op + sz);
199 op = (union overhead *)((caddr_t)op + sz);
211 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
212 if (op->ov_magic != MAGIC)
215 op->ov_next = nextf[size]; /* also clobbers ov_magic */
220 __crt_realloc(void *cp, size_t nbytes)
228 return (__crt_malloc(nbytes));
229 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
230 if (op->ov_magic != MAGIC)
231 return (NULL); /* Double-free or bad argument */
234 if (onb < (u_int)pagesz)
237 onb += pagesz - sizeof(*op);
238 /* avoid the copy if same size block */
244 i += pagesz - sizeof(*op);
246 if (nbytes <= onb && nbytes > (size_t)i)
248 if ((res = __crt_malloc(nbytes)) == NULL)
250 bcopy(cp, res, (nbytes < onb) ? nbytes : onb);
261 if (pagepool_end - pagepool_start > pagesz) {
262 addr = (caddr_t)roundup2((long)pagepool_start, pagesz);
263 if (munmap(addr, pagepool_end - addr) != 0) {
265 rtld_fdprintf(STDERR_FILENO, _BASENAME_RTLD ": "
266 "morepages: cannot munmap %p: %s\n",
267 addr, rtld_strerror(errno));
272 offset = (long)pagepool_start - rounddown2((long)pagepool_start,
275 pagepool_start = mmap(0, n * pagesz, PROT_READ | PROT_WRITE,
276 MAP_ANON | MAP_PRIVATE, -1, 0);
277 if (pagepool_start == MAP_FAILED) {
279 rtld_fdprintf(STDERR_FILENO, _BASENAME_RTLD ": morepages: "
280 "cannot mmap anonymous memory: %s\n",
281 rtld_strerror(errno));
285 pagepool_end = pagepool_start + n * pagesz;
286 pagepool_start += offset;