vmstat - Fix formatting
[dragonfly.git] / libexec / rtld-elf / malloc.c
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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.
dc71b7ab 13 * 3. Neither the name of the University nor the names of its contributors
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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
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30/*
31 * malloc.c (Caltech) 2/21/82
32 * Chris Kingsley, kingsley@cit-20.
33 *
34 * This is a very fast storage allocator. It allocates blocks of a small
35 * number of different sizes, and keeps free lists of each size. Blocks that
36 * don't exactly fit are passed up to the next larger size. In this
37 * implementation, the available sizes are 2^n-4 (or 2^n-10) bytes long.
38 * This is designed for use in a virtual memory environment.
39 */
40
41#include <sys/types.h>
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42#include <paths.h>
43#include <stdarg.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <unistd.h>
48#include <sys/param.h>
49#include <sys/mman.h>
abfcd5b1 50#include "rtld_printf.h"
984263bc 51
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52static void morecore();
53static int findbucket();
54
55/*
56 * Pre-allocate mmap'ed pages
57 */
58#define NPOOLPAGES (32*1024/pagesz)
59static caddr_t pagepool_start, pagepool_end;
60static int morepages();
61
62/*
63 * The overhead on a block is at least 4 bytes. When free, this space
64 * contains a pointer to the next free block, and the bottom two bits must
65 * be zero. When in use, the first byte is set to MAGIC, and the second
66 * byte is the size index. The remaining bytes are for alignment.
67 * If range checking is enabled then a second word holds the size of the
68 * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
69 * The order of elements is critical: ov_magic must overlay the low order
70 * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
71 */
72union overhead {
73 union overhead *ov_next; /* when free */
74 struct {
75 u_char ovu_magic; /* magic number */
76 u_char ovu_index; /* bucket # */
77#ifdef RCHECK
78 u_short ovu_rmagic; /* range magic number */
79 u_int ovu_size; /* actual block size */
80#endif
81 } ovu;
82#define ov_magic ovu.ovu_magic
83#define ov_index ovu.ovu_index
84#define ov_rmagic ovu.ovu_rmagic
85#define ov_size ovu.ovu_size
86};
87
88#define MAGIC 0xef /* magic # on accounting info */
89#define RMAGIC 0x5555 /* magic # on range info */
90
91#ifdef RCHECK
92#define RSLOP sizeof (u_short)
93#else
94#define RSLOP 0
95#endif
96
97/*
98 * nextf[i] is the pointer to the next free block of size 2^(i+3). The
99 * smallest allocatable block is 8 bytes. The overhead information
100 * precedes the data area returned to the user.
101 */
102#define NBUCKETS 30
103static union overhead *nextf[NBUCKETS];
104
105static int pagesz; /* page size */
106static int pagebucket; /* page size bucket */
107
108#ifdef MSTATS
109/*
110 * nmalloc[i] is the difference between the number of mallocs and frees
111 * for a given block size.
112 */
113static u_int nmalloc[NBUCKETS];
114#include <stdio.h>
115#endif
116
117#if defined(MALLOC_DEBUG) || defined(RCHECK)
118#define ASSERT(p) if (!(p)) botch("p")
119#include <stdio.h>
120static void
472de6d1 121botch(char *s)
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122{
123 fprintf(stderr, "\r\nassertion botched: %s\r\n", s);
124 (void) fflush(stderr); /* just in case user buffered it */
125 abort();
126}
127#else
128#define ASSERT(p)
129#endif
130
131/* Debugging stuff */
abfcd5b1 132#define TRACE() rtld_printf("TRACE %s:%d\n", __FILE__, __LINE__)
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133
134void *
472de6d1 135malloc(size_t nbytes)
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136{
137 register union overhead *op;
138 register int bucket;
139 register long n;
140 register unsigned amt;
141
142 /*
143 * First time malloc is called, setup page size and
144 * align break pointer so all data will be page aligned.
145 */
146 if (pagesz == 0) {
147 pagesz = n = getpagesize();
148 if (morepages(NPOOLPAGES) == 0)
149 return NULL;
150 op = (union overhead *)(pagepool_start);
151 n = n - sizeof (*op) - ((long)op & (n - 1));
152 if (n < 0)
153 n += pagesz;
154 if (n) {
155 pagepool_start += n;
156 }
157 bucket = 0;
158 amt = 8;
fcf53d9b 159 while ((unsigned)pagesz > amt) {
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160 amt <<= 1;
161 bucket++;
162 }
163 pagebucket = bucket;
164 }
165 /*
166 * Convert amount of memory requested into closest block size
167 * stored in hash buckets which satisfies request.
168 * Account for space used per block for accounting.
169 */
fcf53d9b 170 if (nbytes <= (unsigned long)(n = pagesz - sizeof (*op) - RSLOP)) {
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171#ifndef RCHECK
172 amt = 8; /* size of first bucket */
173 bucket = 0;
174#else
175 amt = 16; /* size of first bucket */
176 bucket = 1;
177#endif
178 n = -(sizeof (*op) + RSLOP);
179 } else {
180 amt = pagesz;
181 bucket = pagebucket;
182 }
183 while (nbytes > amt + n) {
184 amt <<= 1;
185 if (amt == 0)
186 return (NULL);
187 bucket++;
188 }
189 /*
190 * If nothing in hash bucket right now,
191 * request more memory from the system.
192 */
193 if ((op = nextf[bucket]) == NULL) {
194 morecore(bucket);
195 if ((op = nextf[bucket]) == NULL)
196 return (NULL);
197 }
198 /* remove from linked list */
199 nextf[bucket] = op->ov_next;
200 op->ov_magic = MAGIC;
201 op->ov_index = bucket;
202#ifdef MSTATS
203 nmalloc[bucket]++;
204#endif
205#ifdef RCHECK
206 /*
207 * Record allocated size of block and
208 * bound space with magic numbers.
209 */
965b839f 210 op->ov_size = roundup2(nbytes, RSLOP);
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211 op->ov_rmagic = RMAGIC;
212 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
213#endif
214 return ((char *)(op + 1));
215}
216
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217/*
218 * Used by rtld.c, if we don't override it here the calloc from
219 * libc may try to pull in the malloc/realloc/free from libc too.
220 */
221void *
222calloc(size_t num, size_t size)
223{
224 void *p;
225
226 size *= num;
227 if ((p = malloc(size)) != NULL)
228 bzero(p, size);
229 return(p);
230}
231
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232/*
233 * Allocate more memory to the indicated bucket.
234 */
235static void
472de6d1 236morecore(int bucket)
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237{
238 register union overhead *op;
239 register int sz; /* size of desired block */
240 int amt; /* amount to allocate */
241 int nblks; /* how many blocks we get */
242
243 /*
244 * sbrk_size <= 0 only for big, FLUFFY, requests (about
245 * 2^30 bytes on a VAX, I think) or for a negative arg.
246 */
247 sz = 1 << (bucket + 3);
248#ifdef MALLOC_DEBUG
249 ASSERT(sz > 0);
250#else
251 if (sz <= 0)
252 return;
253#endif
254 if (sz < pagesz) {
255 amt = pagesz;
256 nblks = amt / sz;
257 } else {
258 amt = sz + pagesz;
259 nblks = 1;
260 }
261 if (amt > pagepool_end - pagepool_start)
262 if (morepages(amt/pagesz + NPOOLPAGES) == 0)
263 return;
264 op = (union overhead *)pagepool_start;
265 pagepool_start += amt;
266
267 /*
268 * Add new memory allocated to that on
269 * free list for this hash bucket.
270 */
271 nextf[bucket] = op;
272 while (--nblks > 0) {
273 op->ov_next = (union overhead *)((caddr_t)op + sz);
274 op = (union overhead *)((caddr_t)op + sz);
275 }
276}
277
278void
472de6d1 279free(void *cp)
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280{
281 register int size;
282 register union overhead *op;
283
284 if (cp == NULL)
285 return;
286 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
287#ifdef MALLOC_DEBUG
288 ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
289#else
290 if (op->ov_magic != MAGIC)
291 return; /* sanity */
292#endif
293#ifdef RCHECK
294 ASSERT(op->ov_rmagic == RMAGIC);
295 ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
296#endif
297 size = op->ov_index;
298 ASSERT(size < NBUCKETS);
299 op->ov_next = nextf[size]; /* also clobbers ov_magic */
300 nextf[size] = op;
301#ifdef MSTATS
302 nmalloc[size]--;
303#endif
304}
305
306/*
307 * When a program attempts "storage compaction" as mentioned in the
308 * old malloc man page, it realloc's an already freed block. Usually
309 * this is the last block it freed; occasionally it might be farther
310 * back. We have to search all the free lists for the block in order
311 * to determine its bucket: 1st we make one pass thru the lists
312 * checking only the first block in each; if that fails we search
313 * ``realloc_srchlen'' blocks in each list for a match (the variable
314 * is extern so the caller can modify it). If that fails we just copy
315 * however many bytes was given to realloc() and hope it's not huge.
316 */
317int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
318
319void *
472de6d1 320realloc(void *cp, size_t nbytes)
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321{
322 register u_int onb;
323 register int i;
324 union overhead *op;
325 char *res;
326 int was_alloced = 0;
327
328 if (cp == NULL)
329 return (malloc(nbytes));
330 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
331 if (op->ov_magic == MAGIC) {
332 was_alloced++;
333 i = op->ov_index;
334 } else {
335 /*
336 * Already free, doing "compaction".
337 *
338 * Search for the old block of memory on the
339 * free list. First, check the most common
340 * case (last element free'd), then (this failing)
341 * the last ``realloc_srchlen'' items free'd.
342 * If all lookups fail, then assume the size of
343 * the memory block being realloc'd is the
344 * largest possible (so that all "nbytes" of new
345 * memory are copied into). Note that this could cause
346 * a memory fault if the old area was tiny, and the moon
347 * is gibbous. However, that is very unlikely.
348 */
349 if ((i = findbucket(op, 1)) < 0 &&
350 (i = findbucket(op, realloc_srchlen)) < 0)
351 i = NBUCKETS;
352 }
353 onb = 1 << (i + 3);
fcf53d9b 354 if (onb < (u_int)pagesz)
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355 onb -= sizeof (*op) + RSLOP;
356 else
357 onb += pagesz - sizeof (*op) - RSLOP;
358 /* avoid the copy if same size block */
359 if (was_alloced) {
360 if (i) {
361 i = 1 << (i + 2);
362 if (i < pagesz)
363 i -= sizeof (*op) + RSLOP;
364 else
365 i += pagesz - sizeof (*op) - RSLOP;
366 }
fcf53d9b 367 if (nbytes <= onb && nbytes > (size_t)i) {
984263bc 368#ifdef RCHECK
965b839f 369 op->ov_size = roundup2(nbytes, RSLOP);
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370 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
371#endif
372 return(cp);
373 } else
374 free(cp);
375 }
376 if ((res = malloc(nbytes)) == NULL)
377 return (NULL);
378 if (cp != res) /* common optimization if "compacting" */
379 bcopy(cp, res, (nbytes < onb) ? nbytes : onb);
380 return (res);
381}
382
383/*
384 * Search ``srchlen'' elements of each free list for a block whose
385 * header starts at ``freep''. If srchlen is -1 search the whole list.
386 * Return bucket number, or -1 if not found.
387 */
388static int
472de6d1 389findbucket(union overhead *freep, int srchlen)
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390{
391 register union overhead *p;
392 register int i, j;
393
394 for (i = 0; i < NBUCKETS; i++) {
395 j = 0;
396 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
397 if (p == freep)
398 return (i);
399 j++;
400 }
401 }
402 return (-1);
403}
404
405#ifdef MSTATS
406/*
407 * mstats - print out statistics about malloc
408 *
409 * Prints two lines of numbers, one showing the length of the free list
410 * for each size category, the second showing the number of mallocs -
411 * frees for each size category.
412 */
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413void
414mstats(char *s)
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415{
416 register int i, j;
417 register union overhead *p;
418 int totfree = 0,
419 totused = 0;
420
421 fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
422 for (i = 0; i < NBUCKETS; i++) {
423 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
424 ;
425 fprintf(stderr, " %d", j);
426 totfree += j * (1 << (i + 3));
427 }
428 fprintf(stderr, "\nused:\t");
429 for (i = 0; i < NBUCKETS; i++) {
430 fprintf(stderr, " %d", nmalloc[i]);
431 totused += nmalloc[i] * (1 << (i + 3));
432 }
433 fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
434 totused, totfree);
435}
436#endif
437
438
439static int
472de6d1 440morepages(int n)
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441{
442 int fd = -1;
443 int offset;
444
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445 if (pagepool_end - pagepool_start > pagesz) {
446 caddr_t addr = (caddr_t)
965b839f 447 roundup2((long)pagepool_start, pagesz);
984263bc 448 if (munmap(addr, pagepool_end - addr) != 0)
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449 rtld_fdprintf(STDERR_FILENO, "morepages: munmap %p",
450 addr);
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451 }
452
453 offset = (long)pagepool_start - ((long)pagepool_start & ~(pagesz - 1));
454
455 if ((pagepool_start = mmap(0, n * pagesz,
456 PROT_READ|PROT_WRITE,
457 MAP_ANON|MAP_COPY, fd, 0)) == (caddr_t)-1) {
abfcd5b1 458 rtld_printf("Cannot map anonymous memory\n");
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459 return 0;
460 }
461 pagepool_end = pagepool_start + n * pagesz;
462 pagepool_start += offset;
463
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464 return n;
465}