On Tue, Dec 21, 2010 at 10:38 AM, Mark Cave-Ayland
<mark.cave-ayland(a)siriusit.co.uk> wrote:
A casual glance at the source code suggests that
pointers returned by ofmem_malloc() are aligned, but in fact they are not
because sizeof(alloc_desc_t) is added to the final pointer return value. Create some
additional padding after the previous value
of ofmem->next_malloc so we can store the alloc_desc_t underneath the final return
pointer in memory, thus ensuring that the
final pointer is aligned correctly.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland(a)siriusit.co.uk>
---
openbios-devel/libopenbios/ofmem_common.c | 21 +++++++++++++--------
1 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/openbios-devel/libopenbios/ofmem_common.c
b/openbios-devel/libopenbios/ofmem_common.c
index 20a4cba..a4e199c 100644
--- a/openbios-devel/libopenbios/ofmem_common.c
+++ b/openbios-devel/libopenbios/ofmem_common.c
@@ -33,6 +33,11 @@ static inline size_t ALIGN_SIZE(size_t x, size_t a)
return (x + a - 1) & ~(a-1);
}
+static inline void * ALIGN_PTR(uintptr_t x, size_t a)
Uppercase name suggests a macro, please use lowercase.
+{
+ return (void *)((x + a - 1) & ~(a-1));
I'd add spaces inside a-1.
+}
+
static ucell get_ram_size( void )
{
ofmem_t *ofmem = ofmem_arch_get_private();
@@ -102,29 +107,29 @@ void* ofmem_malloc( size_t size )
/* waste at most 4K by taking an entry from the freelist */
if( *pp && (**pp).size < size + 0x1000 ) {
- ret = (char*)*pp + sizeof(alloc_desc_t);
- memset( ret, 0, (**pp).size - sizeof(alloc_desc_t) );
+ ret = (char *)((uintptr_t)*pp + sizeof(alloc_desc_t));
+ memset( (char *)ret, 0, (**pp).size - sizeof(alloc_desc_t) );
There are a lot of char* and void* casts, perhaps type of ret should
be void * to avoid some of them. At least (char *)ret shouldn't be
necessary anyway.
*pp = (**pp).next;
- return ret;
+ return (void *)ret;
}
top = ofmem_arch_get_heap_top();
- if( pointer2cell(ofmem->next_malloc) + size > top ) {
+ ret = (char *)ALIGN_PTR((uintptr_t)ofmem->next_malloc + sizeof(alloc_desc_t),
CONFIG_OFMEM_MALLOC_ALIGN);
+ if( pointer2cell((void *)ret) + size > top ) {
printk("out of malloc memory (%x)!\n", size );
return NULL;
}
- d = (alloc_desc_t*) ofmem->next_malloc;
+ d = (alloc_desc_t*)((uintptr_t)ret - sizeof(alloc_desc_t));
ofmem->next_malloc += size;
d->next = NULL;
d->size = size;
- ret = (char*)d + sizeof(alloc_desc_t);
- memset( ret, 0, size - sizeof(alloc_desc_t) );
+ memset( (char *)ret, 0, size - sizeof(alloc_desc_t) );
- return ret;
+ return (void *)ret;
}
void ofmem_free( void *ptr )
--
1.7.1
--
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