Index: kernel/generic/include/lib/memfnc.h
===================================================================
--- kernel/generic/include/lib/memfnc.h	(revision 630b9d35d680e1630c85e924dedf7b49c34f6e70)
+++ kernel/generic/include/lib/memfnc.h	(revision fab2746a5541d35bc79cbed917f66153231e4a4b)
@@ -50,4 +50,6 @@
     ATTRIBUTE_OPTIMIZE("-fno-tree-loop-distribute-patterns") DO_NOT_DISCARD;
 
+#define alloca(size) __builtin_alloca((size))
+
 #endif