ARC: DWARF2 .debug_frame based stack unwinder

-Originally written by Rajeshwar Ranga
-Derived off of generic unwinder in 2.6.19 and adapted to ARC

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Rajeshwar Ranga <rajeshwar.ranga@gmail.com>
diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
index 46c15ff..38e4715 100644
--- a/arch/arc/kernel/Makefile
+++ b/arch/arc/kernel/Makefile
@@ -14,10 +14,16 @@
 
 obj-$(CONFIG_MODULES)			+= arcksyms.o module.o
 obj-$(CONFIG_SMP) 			+= smp.o
+obj-$(CONFIG_ARC_DW2_UNWIND)		+= unwind.o
 
 obj-$(CONFIG_ARC_FPU_SAVE_RESTORE)	+= fpu.o
 CFLAGS_fpu.o   += -mdpfp
 
+ifdef CONFIG_ARC_DW2_UNWIND
+CFLAGS_ctx_sw.o += -fno-omit-frame-pointer
+obj-y += ctx_sw.o
+else
 obj-y += ctx_sw_asm.o
+endif
 
 extra-y := vmlinux.lds head.o