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[malloc] Allow allocation of memory with a specified alignment offset

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Allow for allocation of memory blocks having a specified offset from a
specified physical alignment, such as being 12 bytes before a 2kB
boundary.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2012-08-29 15:35:46 +01:00
parent de802310bc
commit e2becce186
2 changed files with 31 additions and 10 deletions
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12
src/core/malloc.c
View File

@ -220,6 +220,7 @@ static void discard_all_cache ( void ) {
*
* @v size Requested size
* @v align Physical alignment
* @v offset Offset from physical alignment
* @ret ptr Memory block, or NULL
*
* Allocates a memory block @b physically aligned as requested. No
@ -227,7 +228,7 @@ static void discard_all_cache ( void ) {
*
* @c align must be a power of two. @c size may not be zero.
*/
void * alloc_memblock ( size_t size, size_t align ) {
void * alloc_memblock ( size_t size, size_t align, size_t offset ) {
struct memory_block *block;
size_t align_mask;
size_t pre_size;
@ -244,12 +245,13 @@ void * alloc_memblock ( size_t size, size_t align ) {
size = ( size + MIN_MEMBLOCK_SIZE - 1 ) & ~( MIN_MEMBLOCK_SIZE - 1 );
align_mask = ( align - 1 ) | ( MIN_MEMBLOCK_SIZE - 1 );
DBG ( "Allocating %#zx (aligned %#zx)\n", size, align );
DBG ( "Allocating %#zx (aligned %#zx+%zx)\n", size, align, offset );
while ( 1 ) {
/* Search through blocks for the first one with enough space */
list_for_each_entry ( block, &free_blocks, list ) {
pre_size = ( - virt_to_phys ( block ) ) & align_mask;
post_size = block->size - pre_size - size;
pre_size = ( ( offset - virt_to_phys ( block ) )
& align_mask );
post_size = ( block->size - pre_size - size );
if ( post_size >= 0 ) {
/* Split block into pre-block, block, and
* post-block. After this split, the "pre"
@ -418,7 +420,7 @@ void * realloc ( void *old_ptr, size_t new_size ) {
if ( new_size ) {
new_total_size = ( new_size +
offsetof ( struct autosized_block, data ) );
new_block = alloc_memblock ( new_total_size, 1 );
new_block = alloc_memblock ( new_total_size, 1, 0 );
if ( ! new_block )
return NULL;
VALGRIND_MAKE_MEM_UNDEFINED ( new_block, offsetof ( struct autosized_block, data ) );

29
src/include/ipxe/malloc.h
View File

@ -23,11 +23,33 @@ FILE_LICENCE ( GPL2_OR_LATER );
extern size_t freemem;
extern void * __malloc alloc_memblock ( size_t size, size_t align );
extern void * __malloc alloc_memblock ( size_t size, size_t align,
size_t offset );
extern void free_memblock ( void *ptr, size_t size );
extern void mpopulate ( void *start, size_t len );
extern void mdumpfree ( void );
/**
* Allocate memory for DMA
*
* @v size Requested size
* @v align Physical alignment
* @v offset Offset from physical alignment
* @ret ptr Memory, or NULL
*
* Allocates physically-aligned memory for DMA.
*
* @c align must be a power of two. @c size may not be zero.
*/
static inline void * __malloc malloc_dma_offset ( size_t size,
size_t phys_align,
size_t offset ) {
void * ptr = alloc_memblock ( size, phys_align, offset );
if ( ptr && size )
VALGRIND_MALLOCLIKE_BLOCK ( ptr, size, 0, 0 );
return ptr;
}
/**
* Allocate memory for DMA
*
@ -40,10 +62,7 @@ extern void mdumpfree ( void );
* @c align must be a power of two. @c size may not be zero.
*/
static inline void * __malloc malloc_dma ( size_t size, size_t phys_align ) {
void * ptr = alloc_memblock ( size, phys_align );
if ( ptr && size )
VALGRIND_MALLOCLIKE_BLOCK ( ptr, size, 0, 0 );
return ptr;
return malloc_dma_offset ( size, phys_align, 0 );
}
/**