coreboot-kgpe-d16/payloads/libpayload/libc/malloc.c

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/*
* This file is part of the libpayload project.
*
* Copyright (C) 2008 Advanced Micro Devices, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* This is a classically weak malloc() implementation. We have a relatively
* small and static heap, so we take the easy route with an O(N) loop
* through the tree for every malloc() and free(). Obviously, this doesn't
* scale past a few hundred KB (if that).
*
* We're also susceptible to the usual buffer overrun poisoning, though the
* risk is within acceptable ranges for this implementation (don't overrun
* your buffers, kids!).
*/
#include <libpayload.h>
extern char _heap, _eheap; /* Defined in the ldscript. */
static void *hstart = (void *)&_heap;
static void *hend = (void *)&_eheap;
typedef unsigned int hdrtype_t;
#define MAGIC (0x2a << 26)
#define FLAG_FREE (1 << 25)
#define FLAG_USED (1 << 24)
#define SIZE(_h) ((_h) & 0xFFFFFF)
#define _HEADER(_s, _f) ((hdrtype_t) (MAGIC | (_f) | ((_s) & 0xFFFFFF)))
#define FREE_BLOCK(_s) _HEADER(_s, FLAG_FREE)
#define USED_BLOCK(_s) _HEADER(_s, FLAG_USED)
#define HDRSIZE (sizeof(hdrtype_t))
#define IS_FREE(_h) (((_h) & (MAGIC | FLAG_FREE)) == (MAGIC | FLAG_FREE))
#define HAS_MAGIC(_h) (((_h) & MAGIC) == MAGIC)
void print_malloc_map(void);
static void setup(void)
{
int size = (unsigned int)(&_eheap - &_heap) - HDRSIZE;
*((hdrtype_t *) hstart) = FREE_BLOCK(size);
}
static void *alloc(int len)
{
hdrtype_t header;
void *ptr = hstart;
/* Align the size. */
len = (len + 3) & ~3;
if (!len || len > 0xffffff)
return (void *)NULL;
/* Make sure the region is setup correctly. */
if (!HAS_MAGIC(*((hdrtype_t *) ptr)))
setup();
/* Find some free space. */
do {
header = *((hdrtype_t *) ptr);
int size = SIZE(header);
if (!HAS_MAGIC(header) || size == 0) {
printf("memory allocator panic.\n");
halt();
}
if (header & FLAG_FREE) {
if (len <= size) {
void *nptr = ptr + (HDRSIZE + len);
int nsize = size - (HDRSIZE + len);
/* Mark the block as used. */
*((hdrtype_t *) ptr) = USED_BLOCK(len);
/* If there is still room in this block,
* then mark it as such.
*/
if (nsize > 0)
*((hdrtype_t *) nptr) =
FREE_BLOCK(nsize);
return (void *)(ptr + HDRSIZE);
}
}
ptr += HDRSIZE + size;
} while (ptr < hend);
/* Nothing available. */
return (void *)NULL;
}
static void _consolidate(void)
{
void *ptr = hstart;
while (ptr < hend) {
void *nptr;
hdrtype_t hdr = *((hdrtype_t *) ptr);
unsigned int size = 0;
if (!IS_FREE(hdr)) {
ptr += HDRSIZE + SIZE(hdr);
continue;
}
size = SIZE(hdr);
nptr = ptr + HDRSIZE + SIZE(hdr);
while (nptr < hend) {
hdrtype_t nhdr = *((hdrtype_t *) nptr);
if (!(IS_FREE(nhdr)))
break;
size += SIZE(nhdr) + HDRSIZE;
*((hdrtype_t *) nptr) = 0;
nptr += (HDRSIZE + SIZE(nhdr));
}
*((hdrtype_t *) ptr) = FREE_BLOCK(size);
ptr = nptr;
}
}
void free(void *ptr)
{
hdrtype_t hdr;
ptr -= HDRSIZE;
/* Sanity check. */
if (ptr < hstart || ptr >= hend)
return;
hdr = *((hdrtype_t *) ptr);
/* Not our header (we're probably poisoned). */
if (!HAS_MAGIC(hdr))
return;
/* Double free. */
if (hdr & FLAG_FREE)
return;
*((hdrtype_t *) ptr) = FREE_BLOCK(SIZE(hdr));
_consolidate();
}
void *malloc(size_t size)
{
return alloc(size);
}
void *calloc(size_t nmemb, size_t size)
{
size_t total = nmemb * size;
void *ptr = alloc(total);
if (ptr)
memset(ptr, 0, total);
return ptr;
}
void *realloc(void *ptr, size_t size)
{
void *ret, *pptr;
unsigned int osize;
if (ptr == NULL)
return alloc(size);
pptr = ptr - HDRSIZE;
if (!HAS_MAGIC(*((hdrtype_t *) pptr)))
return NULL;
/* Get the original size of the block. */
osize = SIZE(*((hdrtype_t *) pptr));
/*
* Free the memory to update the tables - this won't touch the actual
* memory, so we can still use it for the copy after we have
* reallocated the new space.
*/
free(ptr);
ret = alloc(size);
/*
* if ret == NULL, then doh - failure.
* if ret == ptr then woo-hoo! no copy needed.
*/
if (ret == NULL || ret == ptr)
return ret;
/* Copy the memory to the new location. */
memcpy(ret, ptr, osize > size ? size : osize);
return ret;
}
/* This is for debugging purposes. */
#ifdef TEST
void print_malloc_map(void)
{
void *ptr = hstart;
while (ptr < hend) {
hdrtype_t hdr = *((hdrtype_t *) ptr);
if (!HAS_MAGIC(hdr)) {
printf("Poisoned magic - we're toast\n");
break;
}
/* FIXME: Verify the size of the block. */
printf("%x: %s (%x bytes)\n",
(unsigned int)(ptr - hstart),
hdr & FLAG_FREE ? "FREE" : "USED", SIZE(hdr));
ptr += HDRSIZE + SIZE(hdr);
}
}
#endif