2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1983 Regents of the University of California.
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8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
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16 * may be used to endorse or promote products derived from this software
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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
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25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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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"
58 #include "rtld_paths.h"
59 #include "rtld_malloc.h"
62 * Pre-allocate mmap'ed pages
64 #define NPOOLPAGES (128*1024/pagesz)
65 static caddr_t pagepool_start, pagepool_end;
68 * The overhead on a block is at least 4 bytes. When free, this space
69 * contains a pointer to the next free block, and the bottom two bits must
70 * be zero. When in use, the first byte is set to MAGIC, and the second
71 * byte is the size index. The remaining bytes are for alignment.
74 union overhead *ov_next; /* when free */
76 u_char ovu_magic; /* magic number */
77 u_char ovu_index; /* bucket # */
79 #define ov_magic ovu.ovu_magic
80 #define ov_index ovu.ovu_index
83 static void morecore(int bucket);
84 static int morepages(int n);
86 #define MAGIC 0xef /* magic # on accounting info */
89 * nextf[i] is the pointer to the next free block of size
90 * (FIRST_BUCKET_SIZE << i). The overhead information precedes the data
91 * area returned to the user.
93 #define FIRST_BUCKET_SIZE 8
95 static union overhead *nextf[NBUCKETS];
97 static int pagesz; /* page size */
100 * The array of supported page sizes is provided by the user, i.e., the
101 * program that calls this storage allocator. That program must initialize
102 * the array before making its first call to allocate storage. The array
103 * must contain at least one page size. The page sizes must be stored in
108 __crt_malloc(size_t nbytes)
115 * First time malloc is called, setup page size.
118 pagesz = pagesizes[0];
120 * Convert amount of memory requested into closest block size
121 * stored in hash buckets which satisfies request.
122 * Account for space used per block for accounting.
124 amt = FIRST_BUCKET_SIZE;
126 while (nbytes > amt - sizeof(*op)) {
129 if (amt == 0 || bucket >= NBUCKETS)
133 * If nothing in hash bucket right now,
134 * request more memory from the system.
136 if ((op = nextf[bucket]) == NULL) {
138 if ((op = nextf[bucket]) == NULL)
141 /* remove from linked list */
142 nextf[bucket] = op->ov_next;
143 op->ov_magic = MAGIC;
144 op->ov_index = bucket;
145 return ((char *)(op + 1));
149 __crt_calloc(size_t num, size_t size)
153 if (size != 0 && (num * size) / size != num) {
154 /* size_t overflow. */
158 if ((ret = __crt_malloc(num * size)) != NULL)
159 memset(ret, 0, num * size);
165 * Allocate more memory to the indicated bucket.
171 int sz; /* size of desired block */
172 int amt; /* amount to allocate */
173 int nblks; /* how many blocks we get */
175 sz = FIRST_BUCKET_SIZE << bucket;
183 if (amt > pagepool_end - pagepool_start)
184 if (morepages(amt / pagesz + NPOOLPAGES) == 0 &&
185 /* Retry with min required size */
186 morepages(amt / pagesz) == 0)
188 op = (union overhead *)pagepool_start;
189 pagepool_start += amt;
192 * Add new memory allocated to that on
193 * free list for this hash bucket.
196 while (--nblks > 0) {
197 op->ov_next = (union overhead *)((caddr_t)op + sz);
198 op = (union overhead *)((caddr_t)op + sz);
210 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
211 if (op->ov_magic != MAGIC)
214 op->ov_next = nextf[size]; /* also clobbers ov_magic */
219 __crt_realloc(void *cp, size_t nbytes)
227 return (__crt_malloc(nbytes));
228 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
229 if (op->ov_magic != MAGIC)
230 return (NULL); /* Double-free or bad argument */
233 if (onb < (u_int)pagesz)
236 onb += pagesz - sizeof(*op);
237 /* avoid the copy if same size block */
243 i += pagesz - sizeof(*op);
245 if (nbytes <= onb && nbytes > (size_t)i)
247 if ((res = __crt_malloc(nbytes)) == NULL)
249 bcopy(cp, res, (nbytes < onb) ? nbytes : onb);
260 if (pagepool_end - pagepool_start > pagesz) {
261 addr = roundup2(pagepool_start, pagesz);
262 if (munmap(addr, pagepool_end - addr) != 0) {
264 rtld_fdprintf(STDERR_FILENO, _BASENAME_RTLD ": "
265 "morepages: cannot munmap %p: %s\n",
266 addr, rtld_strerror(errno));
271 offset = (uintptr_t)pagepool_start - rounddown2(
272 (uintptr_t)pagepool_start, pagesz);
274 addr = mmap(0, n * pagesz, PROT_READ | PROT_WRITE,
275 MAP_ANON | MAP_PRIVATE, -1, 0);
276 if (addr == MAP_FAILED) {
278 rtld_fdprintf(STDERR_FILENO, _BASENAME_RTLD ": morepages: "
279 "cannot mmap anonymous memory: %s\n",
280 rtld_strerror(errno));
282 pagepool_start = pagepool_end = NULL;
285 pagepool_start = addr;
286 pagepool_end = pagepool_start + n * pagesz;
287 pagepool_start += offset;