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>

arch/arc/kernel/vmlinux.lds.S

@@ -100,17 +100,38 @@ SECTIONS
 
 	BSS_SECTION(0, 0, 0)
 
+#ifdef CONFIG_ARC_DW2_UNWIND
+	. = ALIGN(PAGE_SIZE);
+	.debug_frame  : {
+		__start_unwind = .;
+		*(.debug_frame)
+		__end_unwind = .;
+	}
+#else
+	/DISCARD/ : {	*(.debug_frame) }
+#endif
+
 	NOTES
 
 	. = ALIGN(PAGE_SIZE);
 	_end = . ;
 
 	STABS_DEBUG
-	DWARF_DEBUG
 	DISCARDS
 
 	.arcextmap 0 : {
 		*(.gnu.linkonce.arcextmap.*)
 		*(.arcextmap.*)
 	}
+
+	/* open-coded because we need .debug_frame seperately for unwinding */
+	.debug_aranges 0 : { *(.debug_aranges) }
+	.debug_pubnames 0 : { *(.debug_pubnames) }
+	.debug_info 0 : { *(.debug_info) }
+	.debug_abbrev 0 : { *(.debug_abbrev) }
+	.debug_line 0 : { *(.debug_line) }
+	.debug_str 0 : { *(.debug_str) }
+	.debug_loc 0 : { *(.debug_loc) }
+	.debug_macinfo 0 : { *(.debug_macinfo) }
+
 }