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/*
* Mach Operating System
* Copyright (c) 1991,1990,1989 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
* HISTORY
* $Log: malloc.c,v $
* Revision 2.7 91/05/14 17:57:34 mrt
* Correcting copyright
*
* Revision 2.6 91/02/14 14:20:26 mrt
* Added new Mach copyright
* [91/02/13 12:41:21 mrt]
*
* Revision 2.5 90/11/05 14:37:33 rpd
* Added malloc_fork* code.
* [90/11/02 rwd]
*
* Add spin_lock_t.
* [90/10/31 rwd]
*
* Revision 2.4 90/08/07 14:31:28 rpd
* Removed RCS keyword nonsense.
*
* Revision 2.3 90/06/02 15:14:00 rpd
* Converted to new IPC.
* [90/03/20 20:56:57 rpd]
*
* Revision 2.2 89/12/08 19:53:59 rwd
* Removed conditionals.
* [89/10/23 rwd]
*
* Revision 2.1 89/08/03 17:09:46 rwd
* Created.
*
*
* 13-Sep-88 Eric Cooper (ecc) at Carnegie Mellon University
* Changed realloc() to copy min(old size, new size) bytes.
* Bug found by Mike Kupfer at Olivetti.
*/
/*
* File: malloc.c
* Author: Eric Cooper, Carnegie Mellon University
* Date: July, 1988
*
* Memory allocator for use with multiple threads.
*/
#include <cthreads.h>
#include "cthread_internals.h"
/*
* C library imports:
*/
extern bcopy();
/*
* Structure of memory block header.
* When free, next points to next block on free list.
* When allocated, fl points to free list.
* Size of header is 4 bytes, so minimum usable block size is 8 bytes.
*/
typedef union header {
union header *next;
struct free_list *fl;
} *header_t;
#define MIN_SIZE 8 /* minimum block size */
typedef struct free_list {
spin_lock_t lock; /* spin lock for mutual exclusion */
header_t head; /* head of free list for this size */
#ifdef DEBUG
int in_use; /* # mallocs - # frees */
#endif DEBUG
} *free_list_t;
/*
* Free list with index i contains blocks of size 2^(i+3) including header.
* Smallest block size is 8, with 4 bytes available to user.
* Size argument to malloc is a signed integer for sanity checking,
* so largest block size is 2^31.
*/
#define NBUCKETS 29
static struct free_list malloc_free_list[NBUCKETS];
static void
more_memory(size, fl)
int size;
register free_list_t fl;
{
register int amount;
register int n;
vm_address_t where;
register header_t h;
kern_return_t r;
if (size <= vm_page_size) {
amount = vm_page_size;
n = vm_page_size / size;
/*
* We lose vm_page_size - n*size bytes here.
*/
} else {
amount = size;
n = 1;
}
MACH_CALL(vm_allocate(mach_task_self(), &where, (vm_size_t) amount, TRUE), r);
h = (header_t) where;
do {
h->next = fl->head;
fl->head = h;
h = (header_t) ((char *) h + size);
} while (--n != 0);
}
char *
malloc(size)
register unsigned int size;
{
register int i, n;
register free_list_t fl;
register header_t h;
if ((int) size < 0) /* sanity check */
return 0;
size += sizeof(union header);
/*
* Find smallest power-of-two block size
* big enough to hold requested size plus header.
*/
i = 0;
n = MIN_SIZE;
while (n < size) {
i += 1;
n <<= 1;
}
ASSERT(i < NBUCKETS);
fl = &malloc_free_list[i];
spin_lock(&fl->lock);
h = fl->head;
if (h == 0) {
/*
* Free list is empty;
* allocate more blocks.
*/
more_memory(n, fl);
h = fl->head;
if (h == 0) {
/*
* Allocation failed.
*/
spin_unlock(&fl->lock);
return 0;
}
}
/*
* Pop block from free list.
*/
fl->head = h->next;
#ifdef DEBUG
fl->in_use += 1;
#endif DEBUG
spin_unlock(&fl->lock);
/*
* Store free list pointer in block header
* so we can figure out where it goes
* at free() time.
*/
h->fl = fl;
/*
* Return pointer past the block header.
*/
return ((char *) h) + sizeof(union header);
}
free(base)
char *base;
{
register header_t h;
register free_list_t fl;
register int i;
if (base == 0)
return;
/*
* Find free list for block.
*/
h = (header_t) (base - sizeof(union header));
fl = h->fl;
i = fl - malloc_free_list;
/*
* Sanity checks.
*/
if (i < 0 || i >= NBUCKETS) {
ASSERT(0 <= i && i < NBUCKETS);
return;
}
if (fl != &malloc_free_list[i]) {
ASSERT(fl == &malloc_free_list[i]);
return;
}
/*
* Push block on free list.
*/
spin_lock(&fl->lock);
h->next = fl->head;
fl->head = h;
#ifdef DEBUG
fl->in_use -= 1;
#endif DEBUG
spin_unlock(&fl->lock);
return;
}
char *
realloc(old_base, new_size)
char *old_base;
unsigned int new_size;
{
register header_t h;
register free_list_t fl;
register int i;
unsigned int old_size;
char *new_base;
if (old_base == 0)
return 0;
/*
* Find size of old block.
*/
h = (header_t) (old_base - sizeof(union header));
fl = h->fl;
i = fl - malloc_free_list;
/*
* Sanity checks.
*/
if (i < 0 || i >= NBUCKETS) {
ASSERT(0 <= i && i < NBUCKETS);
return 0;
}
if (fl != &malloc_free_list[i]) {
ASSERT(fl == &malloc_free_list[i]);
return 0;
}
/*
* Free list with index i contains blocks of size 2^(i+3) including header.
*/
old_size = (1 << (i+3)) - sizeof(union header);
/*
* Allocate new block, copy old bytes, and free old block.
*/
new_base = malloc(new_size);
if (new_base != 0)
bcopy(old_base, new_base, (int) (old_size < new_size ? old_size : new_size));
free(old_base);
return new_base;
}
#ifdef DEBUG
void
print_malloc_free_list()
{
register int i, size;
register free_list_t fl;
register int n;
register header_t h;
int total_used = 0;
int total_free = 0;
fprintf(stderr, " Size In Use Free Total\n");
for (i = 0, size = MIN_SIZE, fl = malloc_free_list;
i < NBUCKETS;
i += 1, size <<= 1, fl += 1) {
spin_lock(&fl->lock);
if (fl->in_use != 0 || fl->head != 0) {
total_used += fl->in_use * size;
for (n = 0, h = fl->head; h != 0; h = h->next, n += 1)
;
total_free += n * size;
fprintf(stderr, "%10d %10d %10d %10d\n",
size, fl->in_use, n, fl->in_use + n);
}
spin_unlock(&fl->lock);
}
fprintf(stderr, " all sizes %10d %10d %10d\n",
total_used, total_free, total_used + total_free);
}
#endif DEBUG
void malloc_fork_prepare()
/*
* Prepare the malloc module for a fork by insuring that no thread is in a
* malloc critical section.
*/
{
register int i;
for (i = 0; i < NBUCKETS; i++) {
spin_lock(&malloc_free_list[i].lock);
}
}
void malloc_fork_parent()
/*
* Called in the parent process after a fork() to resume normal operation.
*/
{
register int i;
for (i = NBUCKETS-1; i >= 0; i--) {
spin_unlock(&malloc_free_list[i].lock);
}
}
void malloc_fork_child()
/*
* Called in the child process after a fork() to resume normal operation.
*/
{
register int i;
for (i = NBUCKETS-1; i >= 0; i--) {
spin_unlock(&malloc_free_list[i].lock);
}
}
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