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check bad (modified) addresses on freelist before using them
[unix-history] / usr / src / sys / kern / kern_malloc.c
/*
* Copyright (c) 1987, 1991 The Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*
* @(#)kern_malloc.c 7.37 (Berkeley) %G%
*/
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/map.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
struct kmembuckets bucket[MINBUCKET + 16];
struct kmemstats kmemstats[M_LAST];
struct kmemusage *kmemusage;
char *memname[] = INITKMEMNAMES;
char *kmembase, *kmemlimit;
char *memname[] = INITKMEMNAMES;
long malloc_reentered;
#define IN { if (malloc_reentered) panic("malloc reentered");\
else malloc_reentered = 1;}
#define OUT (malloc_reentered = 0)
#ifdef DIAGNOSTIC
/*
* This structure provides a set of masks to catch unaligned frees.
*/
long addrmask[] = { 0,
0x00000001, 0x00000003, 0x00000007, 0x0000000f,
0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
};
/*
* The WEIRD_ADDR is used as known text to copy into free objects so
* that modifications after frees can be detected.
*/
#define WEIRD_ADDR 0xdeadbeef
#define MAX_COPY 32
/*
* Normally the first word of the structure is used to hold the list
* pointer for free objects. However, when running with diagnostics,
* we use the third and fourth fields, so as to catch modifications
* in the most commonly trashed first two words.
*/
struct freelist {
long spare0;
short type;
long spare1;
caddr_t next;
};
#else /* !DIAGNOSTIC */
struct freelist {
caddr_t next;
};
#endif /* DIAGNOSTIC */
struct uselist {
struct uselist *next;
caddr_t mem;
long size;
long type;
} *listhd;
/*
* Allocate a block of memory
*/
void *
malloc(size, type, flags)
unsigned long size;
int type, flags;
{
register struct kmembuckets *kbp;
register struct kmemusage *kup;
register struct freelist *freep;
long indx, npg, alloc, allocsize;
int s;
caddr_t va, cp, rp;
#ifdef KMEMSTATS
register struct kmemstats *ksp = &kmemstats[type];
#ifdef DIAGNOSTIC
if (((unsigned long)type) > M_LAST)
panic("malloc - bogus type");
if (type == M_NAMEI)
curproc->p_spare[0]++;
indx = BUCKETINDX(size);
kbp = &bucket[indx];
s = splimp();
IN;
#ifdef KMEMSTATS
while (ksp->ks_memuse >= ksp->ks_limit) {
if (flags & M_NOWAIT) {
OUT;
splx(s);
return ((void *) NULL);
}
if (ksp->ks_limblocks < 65535)
ksp->ks_limblocks++;
OUT;
tsleep((caddr_t)ksp, PSWP+2, memname[type], 0);
IN;
}
ksp->ks_size |= 1 << indx;
#endif
#ifdef DIAGNOSTIC
copysize = 1 << indx < MAX_COPY ? 1 << indx : MAX_COPY;
#endif
if (kbp->kb_next == NULL) {
kbp->kb_last = NULL;
if (size > MAXALLOCSAVE)
allocsize = roundup(size, CLBYTES);
else
allocsize = 1 << indx;
npg = clrnd(btoc(allocsize));
va = (caddr_t) kmem_malloc(kmem_map, (vm_size_t)ctob(npg),
!(flags & M_NOWAIT));
if (va == NULL) {
OUT;
splx(s);
return ((void *) NULL);
}
#ifdef KMEMSTATS
kbp->kb_total += kbp->kb_elmpercl;
#endif
kup = btokup(va);
kup->ku_indx = indx;
if (allocsize > MAXALLOCSAVE) {
if (npg > 65535)
panic("malloc: allocation too large");
kup->ku_pagecnt = npg;
#ifdef KMEMSTATS
ksp->ks_memuse += allocsize;
#endif
goto out;
}
#ifdef KMEMSTATS
kup->ku_freecnt = kbp->kb_elmpercl;
kbp->kb_totalfree += kbp->kb_elmpercl;
#endif
/*
* Just in case we blocked while allocating memory,
* and someone else also allocated memory for this
* bucket, don't assume the list is still empty.
*/
savedlist = kbp->kb_next;
rp = kbp->kb_next; /* returned while blocked in vmemall */
for (cp = kbp->kb_next; cp >= va; cp -= allocsize) {
((caddr_t *)cp)[2] = (cp > va ? cp - allocsize : rp);
if (indx == 7) {
long *lp = (long *)cp;
lp[0] = lp[1] = lp[3] = lp[4] = -1;
}
}
}
va = kbp->kb_next;
kbp->kb_next = ((caddr_t *)va)[2];
if (indx == 7) {
long *lp = (long *)va;
if (lp[0] != -1 || lp[1] != -1 || lp[3] != -1 || lp[4] != -1)
panic("malloc meddled");
}
#ifdef KMEMSTATS
kup = btokup(va);
if (kup->ku_indx != indx)
panic("malloc: wrong bucket");
if (kup->ku_freecnt == 0)
panic("malloc: lost data");
kup->ku_freecnt--;
kbp->kb_totalfree--;
ksp->ks_memuse += 1 << indx;
out:
kbp->kb_calls++;
ksp->ks_inuse++;
ksp->ks_calls++;
if (ksp->ks_memuse > ksp->ks_maxused)
ksp->ks_maxused = ksp->ks_memuse;
#else
out:
#endif
if (size > 64 && size <= 128) {
mlp = (struct uselist *)malloc(sizeof(*mlp), M_TEMP, M_WAITOK);
mlp->type = type;
mlp->size = size;
mlp->mem = va;
mlp->next = listhd;
listhd = mlp;
}
OUT;
splx(s);
return ((void *) va);
}
#ifdef DIAGNOSTIC
long addrmask[] = { 0x00000000,
0x00000001, 0x00000003, 0x00000007, 0x0000000f,
0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
};
#endif /* DIAGNOSTIC */
/*
* Free a block of memory allocated by malloc.
*/
void
free(addr, type)
void *addr;
int type;
{
register struct kmembuckets *kbp;
register struct kmemusage *kup;
register struct freelist *freep;
long size;
int s;
#ifdef DIAGNOSTIC
caddr_t cp;
long *end, *lp, alloc, copysize;
#endif
#ifdef KMEMSTATS
register struct kmemstats *ksp = &kmemstats[type];
#endif
kup = btokup(addr);
size = 1 << kup->ku_indx;
#ifdef DIAGNOSTIC
if (size > NBPG * CLSIZE)
alloc = addrmask[BUCKETINDX(NBPG * CLSIZE)];
else
alloc = addrmask[kup->ku_indx];
if (((u_long)addr & alloc) != 0) {
printf("free: unaligned addr 0x%x, size %d, type %d, mask %d\n",
addr, size, type, alloc);
panic("free: unaligned addr");
}
#endif /* DIAGNOSTIC */
size = 1 << kup->ku_indx;
kbp = &bucket[kup->ku_indx];
s = splimp();
if (size == 128) {
struct uselist *mlp, *pmlp;
mlp = listhd;
if (mlp->mem == addr)
listhd = mlp->next;
else for (pmlp = mlp, mlp = mlp->next ; mlp; mlp = mlp->next) {
if (mlp->mem == addr) {
pmlp->next = mlp->next;
break;
}
pmlp = mlp;
}
if (mlp == NULL)
printf("free: lost type %s size %d\n", memname[type],
size);
else
free(mlp, M_TEMP);
}
#ifdef DIAGNOSTIC
/*
* Check for returns of data that do not point to the
* beginning of the allocation.
*/
if (type == M_NAMEI)
curproc->p_spare[0]--;
if (size > NBPG * CLSIZE)
alloc = addrmask[BUCKETINDX(NBPG * CLSIZE)];
else
alloc = addrmask[kup->ku_indx];
if (((u_long)addr & alloc) != 0)
panic("free: unaligned addr 0x%x, size %d, type %s, mask %d\n",
addr, size, memname[type], alloc);
#endif /* DIAGNOSTIC */
IN;
if (size > MAXALLOCSAVE) {
kmem_free(kmem_map, (vm_offset_t)addr, ctob(kup->ku_pagecnt));
#ifdef KMEMSTATS
size = kup->ku_pagecnt << PGSHIFT;
ksp->ks_memuse -= size;
kup->ku_indx = 0;
kup->ku_pagecnt = 0;
if (ksp->ks_memuse + size >= ksp->ks_limit &&
ksp->ks_memuse < ksp->ks_limit)
wakeup((caddr_t)ksp);
ksp->ks_inuse--;
kbp->kb_total -= 1;
#endif
splx(s);
return;
}
freep = (struct freelist *)addr;
#ifdef DIAGNOSTIC
/*
* Check for multiple frees. Use a quick check to see if
* it looks free before laboriously searching the freelist.
*/
if (freep->spare0 == WEIRD_ADDR) {
for (cp = kbp->kb_next; cp; cp = *(caddr_t *)cp) {
if (addr != cp)
continue;
printf("multiply freed item 0x%x\n", addr);
panic("free: duplicated free");
}
}
/*
* Copy in known text to detect modification after freeing
* and to make it look free. Also, save the type being freed
* so we can list likely culprit if modification is detected
* when the object is reallocated.
*/
copysize = size < MAX_COPY ? size : MAX_COPY;
end = (long *)&((caddr_t)addr)[copysize];
for (lp = (long *)addr; lp < end; lp++)
*lp = WEIRD_ADDR;
freep->type = type;
#endif /* DIAGNOSTIC */
if (size == 128) {
long *lp = (long *)addr;
lp[0] = lp[1] = lp[3] = lp[4] = -1;
}
#ifdef KMEMSTATS
kup->ku_freecnt++;
if (kup->ku_freecnt >= kbp->kb_elmpercl)
if (kup->ku_freecnt > kbp->kb_elmpercl)
panic("free: multiple frees");
else if (kbp->kb_totalfree > kbp->kb_highwat)
kbp->kb_couldfree++;
kbp->kb_totalfree++;
ksp->ks_memuse -= size;
if (ksp->ks_memuse + size >= ksp->ks_limit &&
ksp->ks_memuse < ksp->ks_limit)
wakeup((caddr_t)ksp);
ksp->ks_inuse--;
#endif
if (kbp->kb_next == NULL)
kbp->kb_next = addr;
else
((struct freelist *)kbp->kb_last)->next = addr;
freep->next = NULL;
kbp->kb_last = addr;
OUT;
splx(s);
}
/*
* Initialize the kernel memory allocator
*/
kmeminit()
{
register long indx;
int npg;
#if ((MAXALLOCSAVE & (MAXALLOCSAVE - 1)) != 0)
ERROR!_kmeminit:_MAXALLOCSAVE_not_power_of_2
#endif
#if (MAXALLOCSAVE > MINALLOCSIZE * 32768)
ERROR!_kmeminit:_MAXALLOCSAVE_too_big
#endif
#if (MAXALLOCSAVE < CLBYTES)
ERROR!_kmeminit:_MAXALLOCSAVE_too_small
#endif
npg = VM_KMEM_SIZE/ NBPG;
kmemusage = (struct kmemusage *) kmem_alloc(kernel_map,
(vm_size_t)(npg * sizeof(struct kmemusage)));
kmem_map = kmem_suballoc(kernel_map, (vm_offset_t *)&kmembase,
(vm_offset_t *)&kmemlimit, (vm_size_t)(npg * NBPG), FALSE);
#ifdef KMEMSTATS
for (indx = 0; indx < MINBUCKET + 16; indx++) {
if (1 << indx >= CLBYTES)
bucket[indx].kb_elmpercl = 1;
else
bucket[indx].kb_elmpercl = CLBYTES / (1 << indx);
bucket[indx].kb_highwat = 5 * bucket[indx].kb_elmpercl;
}
for (indx = 0; indx < M_LAST; indx++)
kmemstats[indx].ks_limit = npg * NBPG * 6 / 10;
#endif
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.