powerpc/booke: Add Stack Marking support to Booke Exception Prolog

This patch adds a marker to the exception stack frame to aid in debugging.
It's already inserted on other platforms and xmon recognizes it and
identifies exception frames when showing stack traces.
Signed-off-by: Torez Smith  <lnxtorez@linux.vnet.ibm.com>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

arch/powerpc/kernel/head_booke.h

 #ifndef __HEAD_BOOKE_H__
 #define __HEAD_BOOKE_H__
 
+#include <asm/ptrace.h>	/* for STACK_FRAME_REGS_MARKER */
 /*
  * Macros used for common Book-e exception handling
  */
@@ -48,6 +49,9 @@
 	stw	r10,0(r11);						     \
 	rlwinm	r9,r9,0,14,12;		/* clear MSR_WE (necessary?)	   */\
 	stw	r0,GPR0(r11);						     \
+	lis	r10, STACK_FRAME_REGS_MARKER@ha;/* exception frame marker */ \
+	addi	r10, r10, STACK_FRAME_REGS_MARKER@l;			     \
+	stw	r10, 8(r11);						     \
 	SAVE_4GPRS(3, r11);						     \
 	SAVE_2GPRS(7, r11)