xref: /netbsd-src/sys/kern/kern_malloc.c (revision 1ca5c1b28139779176bd5c13ad7c5f25c0bcd5f8)
1 /*	$NetBSD: kern_malloc.c,v 1.70 2001/12/05 01:29:04 enami Exp $	*/
2 
3 /*
4  * Copyright (c) 1996 Christopher G. Demetriou.  All rights reserved.
5  * Copyright (c) 1987, 1991, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  *	@(#)kern_malloc.c	8.4 (Berkeley) 5/20/95
37  */
38 
39 #include <sys/cdefs.h>
40 __KERNEL_RCSID(0, "$NetBSD: kern_malloc.c,v 1.70 2001/12/05 01:29:04 enami Exp $");
41 
42 #include "opt_lockdebug.h"
43 
44 #include <sys/param.h>
45 #include <sys/proc.h>
46 #include <sys/map.h>
47 #include <sys/kernel.h>
48 #include <sys/malloc.h>
49 #include <sys/systm.h>
50 
51 #include <uvm/uvm_extern.h>
52 
53 static struct vm_map kmem_map_store;
54 struct vm_map *kmem_map = NULL;
55 
56 #include "opt_kmempages.h"
57 
58 #ifdef NKMEMCLUSTERS
59 #error NKMEMCLUSTERS is obsolete; remove it from your kernel config file and use NKMEMPAGES instead or let the kernel auto-size
60 #endif
61 
62 /*
63  * Default number of pages in kmem_map.  We attempt to calculate this
64  * at run-time, but allow it to be either patched or set in the kernel
65  * config file.
66  */
67 #ifndef NKMEMPAGES
68 #define	NKMEMPAGES	0
69 #endif
70 int	nkmempages = NKMEMPAGES;
71 
72 /*
73  * Defaults for lower- and upper-bounds for the kmem_map page count.
74  * Can be overridden by kernel config options.
75  */
76 #ifndef	NKMEMPAGES_MIN
77 #define	NKMEMPAGES_MIN	NKMEMPAGES_MIN_DEFAULT
78 #endif
79 
80 #ifndef NKMEMPAGES_MAX
81 #define	NKMEMPAGES_MAX	NKMEMPAGES_MAX_DEFAULT
82 #endif
83 
84 #include "opt_kmemstats.h"
85 #include "opt_malloclog.h"
86 
87 struct kmembuckets bucket[MINBUCKET + 16];
88 struct kmemstats kmemstats[M_LAST];
89 struct kmemusage *kmemusage;
90 char *kmembase, *kmemlimit;
91 const char * const memname[] = INITKMEMNAMES;
92 
93 #ifdef MALLOCLOG
94 #ifndef MALLOCLOGSIZE
95 #define	MALLOCLOGSIZE	100000
96 #endif
97 
98 struct malloclog {
99 	void *addr;
100 	long size;
101 	int type;
102 	int action;
103 	const char *file;
104 	long line;
105 } malloclog[MALLOCLOGSIZE];
106 
107 long	malloclogptr;
108 
109 static void domlog(void *, long, int, int, const char *, long);
110 static void hitmlog(void *);
111 
112 static void
113 domlog(void *a, long size, int type, int action, const char *file, long line)
114 {
115 
116 	malloclog[malloclogptr].addr = a;
117 	malloclog[malloclogptr].size = size;
118 	malloclog[malloclogptr].type = type;
119 	malloclog[malloclogptr].action = action;
120 	malloclog[malloclogptr].file = file;
121 	malloclog[malloclogptr].line = line;
122 	malloclogptr++;
123 	if (malloclogptr >= MALLOCLOGSIZE)
124 		malloclogptr = 0;
125 }
126 
127 static void
128 hitmlog(void *a)
129 {
130 	struct malloclog *lp;
131 	long l;
132 
133 #define	PRT do { \
134 	if (malloclog[l].addr == a && malloclog[l].action) { \
135 		lp = &malloclog[l]; \
136 		printf("malloc log entry %ld:\n", l); \
137 		printf("\taddr = %p\n", lp->addr); \
138 		printf("\tsize = %ld\n", lp->size); \
139 		printf("\ttype = %s\n", memname[lp->type]); \
140 		printf("\taction = %s\n", lp->action == 1 ? "alloc" : "free"); \
141 		printf("\tfile = %s\n", lp->file); \
142 		printf("\tline = %ld\n", lp->line); \
143 	} \
144 } while (/* CONSTCOND */0)
145 
146 	for (l = malloclogptr; l < MALLOCLOGSIZE; l++)
147 		PRT;
148 
149 	for (l = 0; l < malloclogptr; l++)
150 		PRT;
151 }
152 #endif /* MALLOCLOG */
153 
154 #ifdef DIAGNOSTIC
155 /*
156  * This structure provides a set of masks to catch unaligned frees.
157  */
158 const long addrmask[] = { 0,
159 	0x00000001, 0x00000003, 0x00000007, 0x0000000f,
160 	0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
161 	0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
162 	0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
163 };
164 
165 /*
166  * The WEIRD_ADDR is used as known text to copy into free objects so
167  * that modifications after frees can be detected.
168  */
169 #define	WEIRD_ADDR	((unsigned) 0xdeadbeef)
170 #ifdef DEBUG
171 #define	MAX_COPY	PAGE_SIZE
172 #else
173 #define	MAX_COPY	32
174 #endif
175 
176 /*
177  * Normally the freelist structure is used only to hold the list pointer
178  * for free objects.  However, when running with diagnostics, the first
179  * 8 bytes of the structure is unused except for diagnostic information,
180  * and the free list pointer is at offst 8 in the structure.  Since the
181  * first 8 bytes is the portion of the structure most often modified, this
182  * helps to detect memory reuse problems and avoid free list corruption.
183  */
184 struct freelist {
185 	int32_t	spare0;
186 	int16_t	type;
187 	int16_t	spare1;
188 	caddr_t	next;
189 };
190 #else /* !DIAGNOSTIC */
191 struct freelist {
192 	caddr_t	next;
193 };
194 #endif /* DIAGNOSTIC */
195 
196 /*
197  * Allocate a block of memory
198  */
199 #ifdef MALLOCLOG
200 void *
201 _malloc(unsigned long size, int type, int flags, const char *file, long line)
202 #else
203 void *
204 malloc(unsigned long size, int type, int flags)
205 #endif /* MALLOCLOG */
206 {
207 	struct kmembuckets *kbp;
208 	struct kmemusage *kup;
209 	struct freelist *freep;
210 	long indx, npg, allocsize;
211 	int s;
212 	caddr_t va, cp, savedlist;
213 #ifdef DIAGNOSTIC
214 	int32_t *end, *lp;
215 	int copysize;
216 	const char *savedtype;
217 #endif
218 #ifdef KMEMSTATS
219 	struct kmemstats *ksp = &kmemstats[type];
220 
221 	if (__predict_false(((unsigned long)type) > M_LAST))
222 		panic("malloc - bogus type");
223 #endif
224 #ifdef LOCKDEBUG
225 	if ((flags & M_NOWAIT) == 0)
226 		simple_lock_only_held(NULL, "malloc");
227 #endif
228 #ifdef MALLOC_DEBUG
229 	if (debug_malloc(size, type, flags, (void **) &va))
230 		return ((void *) va);
231 #endif
232 	indx = BUCKETINDX(size);
233 	kbp = &bucket[indx];
234 	s = splvm();
235 #ifdef KMEMSTATS
236 	while (ksp->ks_memuse >= ksp->ks_limit) {
237 		if (flags & M_NOWAIT) {
238 			splx(s);
239 			return ((void *) NULL);
240 		}
241 		if (ksp->ks_limblocks < 65535)
242 			ksp->ks_limblocks++;
243 		tsleep((caddr_t)ksp, PSWP+2, memname[type], 0);
244 	}
245 	ksp->ks_size |= 1 << indx;
246 #endif
247 #ifdef DIAGNOSTIC
248 	copysize = 1 << indx < MAX_COPY ? 1 << indx : MAX_COPY;
249 #endif
250 	if (kbp->kb_next == NULL) {
251 		kbp->kb_last = NULL;
252 		if (size > MAXALLOCSAVE)
253 			allocsize = round_page(size);
254 		else
255 			allocsize = 1 << indx;
256 		npg = btoc(allocsize);
257 		va = (caddr_t) uvm_km_kmemalloc(kmem_map, NULL,
258 		    (vsize_t)ctob(npg),
259 		    (flags & M_NOWAIT) ? UVM_KMF_NOWAIT : 0);
260 		if (__predict_false(va == NULL)) {
261 			/*
262 			 * Kmem_malloc() can return NULL, even if it can
263 			 * wait, if there is no map space avaiable, because
264 			 * it can't fix that problem.  Neither can we,
265 			 * right now.  (We should release pages which
266 			 * are completely free and which are in buckets
267 			 * with too many free elements.)
268 			 */
269 			if ((flags & (M_NOWAIT|M_CANFAIL)) == 0)
270 				panic("malloc: out of space in kmem_map");
271 			splx(s);
272 			return ((void *) NULL);
273 		}
274 #ifdef KMEMSTATS
275 		kbp->kb_total += kbp->kb_elmpercl;
276 #endif
277 		kup = btokup(va);
278 		kup->ku_indx = indx;
279 		if (allocsize > MAXALLOCSAVE) {
280 			if (npg > 65535)
281 				panic("malloc: allocation too large");
282 			kup->ku_pagecnt = npg;
283 #ifdef KMEMSTATS
284 			ksp->ks_memuse += allocsize;
285 #endif
286 			goto out;
287 		}
288 #ifdef KMEMSTATS
289 		kup->ku_freecnt = kbp->kb_elmpercl;
290 		kbp->kb_totalfree += kbp->kb_elmpercl;
291 #endif
292 		/*
293 		 * Just in case we blocked while allocating memory,
294 		 * and someone else also allocated memory for this
295 		 * bucket, don't assume the list is still empty.
296 		 */
297 		savedlist = kbp->kb_next;
298 		kbp->kb_next = cp = va + (npg << PAGE_SHIFT) - allocsize;
299 		for (;;) {
300 			freep = (struct freelist *)cp;
301 #ifdef DIAGNOSTIC
302 			/*
303 			 * Copy in known text to detect modification
304 			 * after freeing.
305 			 */
306 			end = (int32_t *)&cp[copysize];
307 			for (lp = (int32_t *)cp; lp < end; lp++)
308 				*lp = WEIRD_ADDR;
309 			freep->type = M_FREE;
310 #endif /* DIAGNOSTIC */
311 			if (cp <= va)
312 				break;
313 			cp -= allocsize;
314 			freep->next = cp;
315 		}
316 		freep->next = savedlist;
317 		if (kbp->kb_last == NULL)
318 			kbp->kb_last = (caddr_t)freep;
319 	}
320 	va = kbp->kb_next;
321 	kbp->kb_next = ((struct freelist *)va)->next;
322 #ifdef DIAGNOSTIC
323 	freep = (struct freelist *)va;
324 	savedtype = (unsigned)freep->type < M_LAST ?
325 		memname[freep->type] : "???";
326 	if (kbp->kb_next) {
327 		int rv;
328 		vaddr_t addr = (vaddr_t)kbp->kb_next;
329 
330 		vm_map_lock(kmem_map);
331 		rv = uvm_map_checkprot(kmem_map, addr,
332 		    addr + sizeof(struct freelist), VM_PROT_WRITE);
333 		vm_map_unlock(kmem_map);
334 
335 		if (__predict_false(rv == 0)) {
336 			printf("Data modified on freelist: "
337 			    "word %ld of object %p size %ld previous type %s "
338 			    "(invalid addr %p)\n",
339 			    (long)((int32_t *)&kbp->kb_next - (int32_t *)kbp),
340 			    va, size, savedtype, kbp->kb_next);
341 #ifdef MALLOCLOG
342 			hitmlog(va);
343 #endif
344 			kbp->kb_next = NULL;
345 		}
346 	}
347 
348 	/* Fill the fields that we've used with WEIRD_ADDR */
349 #if BYTE_ORDER == BIG_ENDIAN
350 	freep->type = WEIRD_ADDR >> 16;
351 #endif
352 #if BYTE_ORDER == LITTLE_ENDIAN
353 	freep->type = (short)WEIRD_ADDR;
354 #endif
355 	end = (int32_t *)&freep->next +
356 	    (sizeof(freep->next) / sizeof(int32_t));
357 	for (lp = (int32_t *)&freep->next; lp < end; lp++)
358 		*lp = WEIRD_ADDR;
359 
360 	/* and check that the data hasn't been modified. */
361 	end = (int32_t *)&va[copysize];
362 	for (lp = (int32_t *)va; lp < end; lp++) {
363 		if (__predict_true(*lp == WEIRD_ADDR))
364 			continue;
365 		printf("Data modified on freelist: "
366 		    "word %ld of object %p size %ld previous type %s "
367 		    "(0x%x != 0x%x)\n",
368 		    (long)(lp - (int32_t *)va), va, size,
369 		    savedtype, *lp, WEIRD_ADDR);
370 #ifdef MALLOCLOG
371 		hitmlog(va);
372 #endif
373 		break;
374 	}
375 
376 	freep->spare0 = 0;
377 #endif /* DIAGNOSTIC */
378 #ifdef KMEMSTATS
379 	kup = btokup(va);
380 	if (kup->ku_indx != indx)
381 		panic("malloc: wrong bucket");
382 	if (kup->ku_freecnt == 0)
383 		panic("malloc: lost data");
384 	kup->ku_freecnt--;
385 	kbp->kb_totalfree--;
386 	ksp->ks_memuse += 1 << indx;
387 out:
388 	kbp->kb_calls++;
389 	ksp->ks_inuse++;
390 	ksp->ks_calls++;
391 	if (ksp->ks_memuse > ksp->ks_maxused)
392 		ksp->ks_maxused = ksp->ks_memuse;
393 #else
394 out:
395 #endif
396 #ifdef MALLOCLOG
397 	domlog(va, size, type, 1, file, line);
398 #endif
399 	splx(s);
400 	if ((flags & M_ZERO) != 0)
401 		memset(va, 0, size);
402 	return ((void *) va);
403 }
404 
405 /*
406  * Free a block of memory allocated by malloc.
407  */
408 #ifdef MALLOCLOG
409 void
410 _free(void *addr, int type, const char *file, long line)
411 #else
412 void
413 free(void *addr, int type)
414 #endif /* MALLOCLOG */
415 {
416 	struct kmembuckets *kbp;
417 	struct kmemusage *kup;
418 	struct freelist *freep;
419 	long size;
420 	int s;
421 #ifdef DIAGNOSTIC
422 	caddr_t cp;
423 	int32_t *end, *lp;
424 	long alloc, copysize;
425 #endif
426 #ifdef KMEMSTATS
427 	struct kmemstats *ksp = &kmemstats[type];
428 #endif
429 
430 #ifdef MALLOC_DEBUG
431 	if (debug_free(addr, type))
432 		return;
433 #endif
434 
435 #ifdef DIAGNOSTIC
436 	/*
437 	 * Ensure that we're free'ing something that we could
438 	 * have allocated in the first place.  That is, check
439 	 * to see that the address is within kmem_map.
440 	 */
441 	if (__predict_false((vaddr_t)addr < kmem_map->header.start ||
442 	    (vaddr_t)addr >= kmem_map->header.end))
443 		panic("free: addr %p not within kmem_map", addr);
444 #endif
445 
446 	kup = btokup(addr);
447 	size = 1 << kup->ku_indx;
448 	kbp = &bucket[kup->ku_indx];
449 	s = splvm();
450 #ifdef MALLOCLOG
451 	domlog(addr, 0, type, 2, file, line);
452 #endif
453 #ifdef DIAGNOSTIC
454 	/*
455 	 * Check for returns of data that do not point to the
456 	 * beginning of the allocation.
457 	 */
458 	if (size > PAGE_SIZE)
459 		alloc = addrmask[BUCKETINDX(PAGE_SIZE)];
460 	else
461 		alloc = addrmask[kup->ku_indx];
462 	if (((u_long)addr & alloc) != 0)
463 		panic("free: unaligned addr %p, size %ld, type %s, mask %ld\n",
464 		    addr, size, memname[type], alloc);
465 #endif /* DIAGNOSTIC */
466 	if (size > MAXALLOCSAVE) {
467 		uvm_km_free(kmem_map, (vaddr_t)addr, ctob(kup->ku_pagecnt));
468 #ifdef KMEMSTATS
469 		size = kup->ku_pagecnt << PGSHIFT;
470 		ksp->ks_memuse -= size;
471 		kup->ku_indx = 0;
472 		kup->ku_pagecnt = 0;
473 		if (ksp->ks_memuse + size >= ksp->ks_limit &&
474 		    ksp->ks_memuse < ksp->ks_limit)
475 			wakeup((caddr_t)ksp);
476 		ksp->ks_inuse--;
477 		kbp->kb_total -= 1;
478 #endif
479 		splx(s);
480 		return;
481 	}
482 	freep = (struct freelist *)addr;
483 #ifdef DIAGNOSTIC
484 	/*
485 	 * Check for multiple frees. Use a quick check to see if
486 	 * it looks free before laboriously searching the freelist.
487 	 */
488 	if (__predict_false(freep->spare0 == WEIRD_ADDR)) {
489 		for (cp = kbp->kb_next; cp;
490 		    cp = ((struct freelist *)cp)->next) {
491 			if (addr != cp)
492 				continue;
493 			printf("multiply freed item %p\n", addr);
494 #ifdef MALLOCLOG
495 			hitmlog(addr);
496 #endif
497 			panic("free: duplicated free");
498 		}
499 	}
500 #ifdef LOCKDEBUG
501 	/*
502 	 * Check if we're freeing a locked simple lock.
503 	 */
504 	simple_lock_freecheck(addr, (char *)addr + size);
505 #endif
506 	/*
507 	 * Copy in known text to detect modification after freeing
508 	 * and to make it look free. Also, save the type being freed
509 	 * so we can list likely culprit if modification is detected
510 	 * when the object is reallocated.
511 	 */
512 	copysize = size < MAX_COPY ? size : MAX_COPY;
513 	end = (int32_t *)&((caddr_t)addr)[copysize];
514 	for (lp = (int32_t *)addr; lp < end; lp++)
515 		*lp = WEIRD_ADDR;
516 	freep->type = type;
517 #endif /* DIAGNOSTIC */
518 #ifdef KMEMSTATS
519 	kup->ku_freecnt++;
520 	if (kup->ku_freecnt >= kbp->kb_elmpercl) {
521 		if (kup->ku_freecnt > kbp->kb_elmpercl)
522 			panic("free: multiple frees");
523 		else if (kbp->kb_totalfree > kbp->kb_highwat)
524 			kbp->kb_couldfree++;
525 	}
526 	kbp->kb_totalfree++;
527 	ksp->ks_memuse -= size;
528 	if (ksp->ks_memuse + size >= ksp->ks_limit &&
529 	    ksp->ks_memuse < ksp->ks_limit)
530 		wakeup((caddr_t)ksp);
531 	ksp->ks_inuse--;
532 #endif
533 	if (kbp->kb_next == NULL)
534 		kbp->kb_next = addr;
535 	else
536 		((struct freelist *)kbp->kb_last)->next = addr;
537 	freep->next = NULL;
538 	kbp->kb_last = addr;
539 	splx(s);
540 }
541 
542 /*
543  * Change the size of a block of memory.
544  */
545 void *
546 realloc(void *curaddr, unsigned long newsize, int type, int flags)
547 {
548 	struct kmemusage *kup;
549 	long cursize;
550 	void *newaddr;
551 #ifdef DIAGNOSTIC
552 	long alloc;
553 #endif
554 
555 	/*
556 	 * realloc() with a NULL pointer is the same as malloc().
557 	 */
558 	if (curaddr == NULL)
559 		return (malloc(newsize, type, flags));
560 
561 	/*
562 	 * realloc() with zero size is the same as free().
563 	 */
564 	if (newsize == 0) {
565 		free(curaddr, type);
566 		return (NULL);
567 	}
568 
569 #ifdef LOCKDEBUG
570 	if ((flags & M_NOWAIT) == 0)
571 		simple_lock_only_held(NULL, "realloc");
572 #endif
573 
574 	/*
575 	 * Find out how large the old allocation was (and do some
576 	 * sanity checking).
577 	 */
578 	kup = btokup(curaddr);
579 	cursize = 1 << kup->ku_indx;
580 
581 #ifdef DIAGNOSTIC
582 	/*
583 	 * Check for returns of data that do not point to the
584 	 * beginning of the allocation.
585 	 */
586 	if (cursize > PAGE_SIZE)
587 		alloc = addrmask[BUCKETINDX(PAGE_SIZE)];
588 	else
589 		alloc = addrmask[kup->ku_indx];
590 	if (((u_long)curaddr & alloc) != 0)
591 		panic("realloc: "
592 		    "unaligned addr %p, size %ld, type %s, mask %ld\n",
593 		    curaddr, cursize, memname[type], alloc);
594 #endif /* DIAGNOSTIC */
595 
596 	if (cursize > MAXALLOCSAVE)
597 		cursize = ctob(kup->ku_pagecnt);
598 
599 	/*
600 	 * If we already actually have as much as they want, we're done.
601 	 */
602 	if (newsize <= cursize)
603 		return (curaddr);
604 
605 	/*
606 	 * Can't satisfy the allocation with the existing block.
607 	 * Allocate a new one and copy the data.
608 	 */
609 	newaddr = malloc(newsize, type, flags);
610 	if (__predict_false(newaddr == NULL)) {
611 		/*
612 		 * malloc() failed, because flags included M_NOWAIT.
613 		 * Return NULL to indicate that failure.  The old
614 		 * pointer is still valid.
615 		 */
616 		return (NULL);
617 	}
618 	memcpy(newaddr, curaddr, cursize);
619 
620 	/*
621 	 * We were successful: free the old allocation and return
622 	 * the new one.
623 	 */
624 	free(curaddr, type);
625 	return (newaddr);
626 }
627 
628 /*
629  * Roundup size to the actual allocation size.
630  */
631 unsigned long
632 malloc_roundup(unsigned long size)
633 {
634 
635 	if (size > MAXALLOCSAVE)
636 		return (roundup(size, PAGE_SIZE));
637 	else
638 		return (1 << BUCKETINDX(size));
639 }
640 
641 /*
642  * Compute the number of pages that kmem_map will map, that is,
643  * the size of the kernel malloc arena.
644  */
645 void
646 kmeminit_nkmempages(void)
647 {
648 	int npages;
649 
650 	if (nkmempages != 0) {
651 		/*
652 		 * It's already been set (by us being here before, or
653 		 * by patching or kernel config options), bail out now.
654 		 */
655 		return;
656 	}
657 
658 	/*
659 	 * We use the following (simple) formula:
660 	 *
661 	 *	- Starting point is physical memory / 4.
662 	 *
663 	 *	- Clamp it down to NKMEMPAGES_MAX.
664 	 *
665 	 *	- Round it up to NKMEMPAGES_MIN.
666 	 */
667 	npages = physmem / 4;
668 
669 	if (npages > NKMEMPAGES_MAX)
670 		npages = NKMEMPAGES_MAX;
671 
672 	if (npages < NKMEMPAGES_MIN)
673 		npages = NKMEMPAGES_MIN;
674 
675 	nkmempages = npages;
676 }
677 
678 /*
679  * Initialize the kernel memory allocator
680  */
681 void
682 kmeminit(void)
683 {
684 #ifdef KMEMSTATS
685 	long indx;
686 #endif
687 
688 #if	((MAXALLOCSAVE & (MAXALLOCSAVE - 1)) != 0)
689 		ERROR!_kmeminit:_MAXALLOCSAVE_not_power_of_2
690 #endif
691 #if	(MAXALLOCSAVE > MINALLOCSIZE * 32768)
692 		ERROR!_kmeminit:_MAXALLOCSAVE_too_big
693 #endif
694 #if	(MAXALLOCSAVE < NBPG)
695 		ERROR!_kmeminit:_MAXALLOCSAVE_too_small
696 #endif
697 
698 	if (sizeof(struct freelist) > (1 << MINBUCKET))
699 		panic("minbucket too small/struct freelist too big");
700 
701 	/*
702 	 * Compute the number of kmem_map pages, if we have not
703 	 * done so already.
704 	 */
705 	kmeminit_nkmempages();
706 
707 	kmemusage = (struct kmemusage *) uvm_km_zalloc(kernel_map,
708 	    (vsize_t)(nkmempages * sizeof(struct kmemusage)));
709 	kmem_map = uvm_km_suballoc(kernel_map, (vaddr_t *)&kmembase,
710 	    (vaddr_t *)&kmemlimit, (vsize_t)(nkmempages << PAGE_SHIFT),
711 	    VM_MAP_INTRSAFE, FALSE, &kmem_map_store);
712 #ifdef KMEMSTATS
713 	for (indx = 0; indx < MINBUCKET + 16; indx++) {
714 		if (1 << indx >= PAGE_SIZE)
715 			bucket[indx].kb_elmpercl = 1;
716 		else
717 			bucket[indx].kb_elmpercl = PAGE_SIZE / (1 << indx);
718 		bucket[indx].kb_highwat = 5 * bucket[indx].kb_elmpercl;
719 	}
720 	for (indx = 0; indx < M_LAST; indx++)
721 		kmemstats[indx].ks_limit =
722 		    ((u_long)nkmempages << PAGE_SHIFT) * 6U / 10U;
723 #endif
724 #ifdef MALLOC_DEBUG
725 	debug_malloc_init();
726 #endif
727 }
728 
729 #ifdef DDB
730 #include <ddb/db_output.h>
731 
732 /*
733  * Dump kmem statistics from ddb.
734  *
735  * usage: call dump_kmemstats
736  */
737 void	dump_kmemstats(void);
738 
739 void
740 dump_kmemstats(void)
741 {
742 #ifdef KMEMSTATS
743 	const char *name;
744 	int i;
745 
746 	for (i = 0; i < M_LAST; i++) {
747 		name = memname[i] ? memname[i] : "";
748 
749 		db_printf("%2d %s%.*s %ld\n", i, name,
750 		    (int)(20 - strlen(name)), "                    ",
751 		    kmemstats[i].ks_memuse);
752 	}
753 #else
754 	db_printf("Kmem stats are not being collected.\n");
755 #endif /* KMEMSTATS */
756 }
757 #endif /* DDB */
758