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

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>

1 files changed, 22 insertions, 3 deletions

diff --git a/src/include/ipxe/malloc.h b/src/include/ipxe/malloc.h
index d41b0562..bbd6cb89 100644
--- a/src/include/ipxe/malloc.h
+++ b/src/include/ipxe/malloc.h
@@ -23,7 +23,8 @@ 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 );
@@ -33,20 +34,38 @@ extern void mdumpfree ( void );
  *
  * @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 ( size_t size, size_t phys_align ) {
-	void * ptr = alloc_memblock ( size, phys_align );
+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
+ *
+ * @v size		Requested size
+ * @v align		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 ( size_t size, size_t phys_align ) {
+	return malloc_dma_offset ( size, phys_align, 0 );
+}
+
+/**
  * Free memory allocated with malloc_dma()
  *
  * @v ptr		Memory allocated by malloc_dma(), or NULL