/*
* Copyright (c) 2009 Martin Decky
* Copyright (c) 2009 Petr Tuma
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - 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 ``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 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.
*/
/** @addtogroup libc
* @{
*/
/** @file
*/
#include <malloc.h>
#include <bool.h>
#include <as.h>
#include <align.h>
#include <macros.h>
#include <assert.h>
#include <errno.h>
#include <bitops.h>
#include <mem.h>
#include <adt/gcdlcm.h>
/* Magic used in heap headers. */
#define HEAP_BLOCK_HEAD_MAGIC 0xBEEF0101
/* Magic used in heap footers. */
#define HEAP_BLOCK_FOOT_MAGIC 0xBEEF0202
/** Allocation alignment (this also covers the alignment of fields
in the heap header and footer) */
#define BASE_ALIGN 16
/**
* Either 4 * 256M on 32-bit architecures or 16 * 256M on 64-bit architectures
*/
#define MAX_HEAP_SIZE (sizeof(uintptr_t) << 28)
/**
*
*/
#define STRUCT_OVERHEAD (sizeof(heap_block_head_t) + sizeof(heap_block_foot_t))
/**
* Calculate real size of a heap block (with header and footer)
*/
#define GROSS_SIZE(size) ((size) + STRUCT_OVERHEAD)
/**
* Calculate net size of a heap block (without header and footer)
*/
#define NET_SIZE(size) ((size) - STRUCT_OVERHEAD)
/** Header of a heap block
*
*/
typedef struct {
/* Size of the block (including header and footer) */
size_t size;
/* Indication of a free block */
/* A magic value to detect overwrite of heap header */
uint32_t magic;
} heap_block_head_t;
/** Footer of a heap block
*
*/
typedef struct {
/* Size of the block (including header and footer) */
size_t size;
/* A magic value to detect overwrite of heap footer */
uint32_t magic;
} heap_block_foot_t;
/** Linker heap symbol */
extern char _heap;
/** Address of heap start */
static void *heap_start = 0;
/** Address of heap end */
static void *heap_end = 0;
/** Maximum heap size */
static size_t max_heap_size = (size_t) -1;
/** Current number of pages of heap area */
static size_t heap_pages = 0;
/** Initialize a heap block
*
* Fills in the structures related to a heap block.
*
* @param addr Address of the block.
* @param size Size of the block including the header and the footer.
* @param free Indication of a free block.
*
*/
static void block_init
(void *addr
, size_t size
, bool
free) {
/* Calculate the position of the header and the footer */
heap_block_head_t *head = (heap_block_head_t *) addr;
heap_block_foot_t *foot =
(heap_block_foot_t *) (addr + size - sizeof(heap_block_foot_t));
head->size = size;
head->magic = HEAP_BLOCK_HEAD_MAGIC;
foot->size = size;
foot->magic = HEAP_BLOCK_FOOT_MAGIC;
}
/** Check a heap block
*
* Verifies that the structures related to a heap block still contain
* the magic constants. This helps detect heap corruption early on.
*
* @param addr Address of the block.
*
*/
static void block_check(void *addr)
{
heap_block_head_t *head = (heap_block_head_t *) addr;
assert(head
->magic
== HEAP_BLOCK_HEAD_MAGIC
);
heap_block_foot_t *foot =
(heap_block_foot_t *) (addr + head->size - sizeof(heap_block_foot_t));
assert(foot
->magic
== HEAP_BLOCK_FOOT_MAGIC
); assert(head
->size
== foot
->size
); }
static bool grow_heap(size_t size)
{
if (size == 0)
return false;
size_t heap_size = (size_t) (heap_end - heap_start);
if ((max_heap_size != (size_t) -1) && (heap_size + size > max_heap_size))
return false;
size_t pages = (size - 1) / PAGE_SIZE + 1;
if (as_area_resize((void *) &_heap, (heap_pages + pages) * PAGE_SIZE, 0)
== EOK) {
void *end = (void *) ALIGN_DOWN(((uintptr_t) &_heap) +
(heap_pages + pages) * PAGE_SIZE, BASE_ALIGN);
block_init(heap_end, end - heap_end, true);
heap_pages += pages;
heap_end = end;
return true;
}
return false;
}
static void shrink_heap(void)
{
// TODO
}
/** Initialize the heap allocator
*
* Finds how much physical memory we have and creates
* the heap management structures that mark the whole
* physical memory as a single free block.
*
*/
void __heap_init(void)
{
if (as_area_create((void *) &_heap, PAGE_SIZE,
AS_AREA_WRITE | AS_AREA_READ)) {
heap_pages = 1;
heap_start = (void *) ALIGN_UP((uintptr_t) &_heap, BASE_ALIGN);
heap_end =
(void *) ALIGN_DOWN(((uintptr_t) &_heap) + PAGE_SIZE, BASE_ALIGN);
/* Make the entire area one large block. */
block_init(heap_start, heap_end - heap_start, true);
}
}
uintptr_t get_max_heap_addr(void)
{
if (max_heap_size == (size_t) -1)
max_heap_size =
max((size_t) (heap_end - heap_start), MAX_HEAP_SIZE);
return ((uintptr_t) heap_start + max_heap_size);
}
static void split_mark(heap_block_head_t *cur, const size_t size)
{
/* See if we should split the block. */
size_t split_limit = GROSS_SIZE(size);
if (cur->size > split_limit) {
/* Block big enough -> split. */
void *next = ((void *) cur) + size;
block_init(next, cur->size - size, true);
block_init(cur, size, false);
} else {
/* Block too small -> use as is. */
}
}
/** Allocate a memory block
*
* @param size The size of the block to allocate.
* @param align Memory address alignment.
*
* @return the address of the block or NULL when not enough memory.
*
*/
static void *malloc_internal(const size_t size, const size_t align)
{
if (align == 0)
return NULL;
size_t falign = lcm(align, BASE_ALIGN);
size_t real_size = GROSS_SIZE(ALIGN_UP(size, falign));
bool grown = false;
void *result;
loop:
result = NULL;
heap_block_head_t *cur = (heap_block_head_t *) heap_start;
while ((result == NULL) && ((void *) cur < heap_end)) {
block_check(cur);
/* Try to find a block that is free and large enough. */
if ((cur
->free) && (cur
->size
>= real_size
)) { /* We have found a suitable block.
Check for alignment properties. */
void *addr = ((void *) cur) + sizeof(heap_block_head_t);
void *aligned = (void *) ALIGN_UP(addr, falign);
if (addr == aligned) {
/* Exact block start including alignment. */
split_mark(cur, real_size);
result = addr;
} else {
/* Block start has to be aligned */
size_t excess = (size_t) (aligned - addr);
if (cur->size >= real_size + excess) {
/* The current block is large enough to fit
data in including alignment */
if ((void *) cur > heap_start) {
/* There is a block before the current block.
This previous block can be enlarged to compensate
for the alignment excess */
heap_block_foot_t *prev_foot =
((void *) cur) - sizeof(heap_block_foot_t);
heap_block_head_t *prev_head =
(heap_block_head_t *) (((void *) cur) - prev_foot->size);
block_check(prev_head);
size_t reduced_size = cur->size - excess;
heap_block_head_t *next_head = ((void *) cur) + excess;
if ((!prev_head
->free) && (excess
>= STRUCT_OVERHEAD
)) { /* The previous block is not free and there is enough
space to fill in a new free block between the previous
and current block */
block_init(cur, excess, true);
} else {
/* The previous block is free (thus there is no need to
induce additional fragmentation to the heap) or the
excess is small, thus just enlarge the previous block */
block_init
(prev_head
, prev_head
->size
+ excess
, prev_head
->free); }
block_init(next_head, reduced_size, true);
split_mark(next_head, real_size);
result = aligned;
cur = next_head;
} else {
/* The current block is the first block on the heap.
We have to make sure that the alignment excess
is large enough to fit a new free block just
before the current block */
while (excess < STRUCT_OVERHEAD) {
aligned += falign;
excess += falign;
}
/* Check for current block size again */
if (cur->size >= real_size + excess) {
size_t reduced_size = cur->size - excess;
cur = (heap_block_head_t *) (heap_start + excess);
block_init(heap_start, excess, true);
block_init(cur, reduced_size, true);
split_mark(cur, real_size);
result = aligned;
}
}
}
}
}
/* Advance to the next block. */
cur = (heap_block_head_t *) (((void *) cur) + cur->size);
}
if ((result == NULL) && (!grown)) {
if (grow_heap(real_size)) {
grown = true;
goto loop;
}
}
return result;
}
void *malloc(const size_t size
) {
return malloc_internal(size, BASE_ALIGN);
}
void *memalign(const size_t align, const size_t size)
{
if (align == 0)
return NULL;
size_t palign =
1 << (fnzb(max(sizeof(void *), align) - 1) + 1);
return malloc_internal(size, palign);
}
void *realloc(const void *addr
, const size_t size
) {
if (addr == NULL)
/* Calculate the position of the header. */
heap_block_head_t *head =
(heap_block_head_t *) (addr - sizeof(heap_block_head_t));
assert((void *) head
>= heap_start
); assert((void *) head
< heap_end
);
block_check(head);
void *ptr = NULL;
size_t real_size = GROSS_SIZE(size);
size_t orig_size = head->size;
if (orig_size > real_size) {
/* Shrink */
if (orig_size - real_size >= STRUCT_OVERHEAD) {
/* Split the original block to a full block
and a tailing free block */
block_init((void *) head, real_size, false);
block_init((void *) head + real_size,
orig_size - real_size, true);
shrink_heap();
}
ptr = ((void *) head) + sizeof(heap_block_head_t);
} else {
/* Look at the next block. If it is free and the size is
sufficient then merge the two. */
heap_block_head_t *next_head =
(heap_block_head_t *) (((void *) head) + head->size);
if (((void *) next_head < heap_end)
&& (head->size + next_head->size >= real_size)) {
block_check(next_head);
block_init(head, head->size + next_head->size, false);
split_mark(head, size);
ptr = ((void *) head) + sizeof(heap_block_head_t);
} else {
if (ptr != NULL) {
memcpy(ptr
, addr
, NET_SIZE
(orig_size
)); }
}
}
return ptr;
}
/** Free a memory block
*
* @param addr The address of the block.
*/
void free(const void *addr
) {
/* Calculate the position of the header. */
heap_block_head_t *head
= (heap_block_head_t *) (addr - sizeof(heap_block_head_t));
assert((void *) head
>= heap_start
); assert((void *) head
< heap_end
);
block_check(head);
/* Mark the block itself as free. */
/* Look at the next block. If it is free, merge the two. */
heap_block_head_t *next_head
= (heap_block_head_t *) (((void *) head) + head->size);
if ((void *) next_head < heap_end) {
block_check(next_head);
block_init(head, head->size + next_head->size, true);
}
/* Look at the previous block. If it is free, merge the two. */
if ((void *) head > heap_start) {
heap_block_foot_t *prev_foot =
(heap_block_foot_t *) (((void *) head) - sizeof(heap_block_foot_t));
heap_block_head_t *prev_head =
(heap_block_head_t *) (((void *) head) - prev_foot->size);
block_check(prev_head);
block_init(prev_head, prev_head->size + head->size, true);
}
shrink_heap();
}
/** @}
*/