boot/efi: fix alignment exception on arm

Change-Id: I8384433c4bed474c3cb82bc8451ecde9a47bcff8
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4656
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: Fredrik Holmqvist <[email protected]>
Reviewed-by: Adrien Destugues <[email protected]>

src/system/boot/platform/efi/arch/arm/arch_start.cpp

@@ -4,6 +4,7 @@
  */
 
 
+#include <kernel.h>
 #include <boot/platform.h>
 #include <boot/stage2.h>
 #include <boot/stdio.h>
@@ -11,6 +12,9 @@
 #include "efi_platform.h"
 
 
+#define ALIGN_MEMORY_MAP	4
+
+
 extern "C" void arch_enter_kernel(uint32_t ttbr, struct kernel_args *kernelArgs,
 	addr_t kernelEntry, addr_t kernelStackTop);
 
@@ -85,7 +89,12 @@ arch_start_kernel(addr_t kernelEntry)
 	// between calls to ExitBootServices.
 	size_t actual_memory_map_size = memory_map_size * 2;
 	memory_map
-		= (efi_memory_descriptor *)kernel_args_malloc(actual_memory_map_size);
+		= (efi_memory_descriptor *)kernel_args_malloc(actual_memory_map_size +
+			ALIGN_MEMORY_MAP);
+
+	// align memory_map to 4-byte boundary
+	// otherwise we get alignment exception when calling GetMemoryMap below
+	memory_map = (efi_memory_descriptor *)ROUNDUP((uint32_t)memory_map, ALIGN_MEMORY_MAP);
 
 	if (memory_map == NULL)
 		panic("Unable to allocate memory map.");