[POWERPC] Set lower flag bits in regs->trap to indicate debug level exception

We use the low bits of regs->trap as flag bits.  We already indicate
critical and machine check level exceptions via this mechanism.  Extend it
to indicate debug level exceptions.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/head_booke.h

@@ -272,7 +272,7 @@
 	/* continue normal handling for a critical exception... */	      \
 2:	mfspr	r4,SPRN_DBSR;						      \
 	addi	r3,r1,STACK_FRAME_OVERHEAD;				      \
-	EXC_XFER_TEMPLATE(DebugException, 0x2002, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), NOCOPY, debug_transfer_to_handler, ret_from_debug_exc)
+	EXC_XFER_TEMPLATE(DebugException, 0x2008, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), NOCOPY, debug_transfer_to_handler, ret_from_debug_exc)
 
 #define DEBUG_CRIT_EXCEPTION						      \
 	START_EXCEPTION(DebugCrit);					      \

include/asm-powerpc/ptrace.h

@@ -119,6 +119,7 @@ extern int ptrace_put_reg(struct task_struct *task, int regno,
 #ifndef __powerpc64__
 #define IS_CRITICAL_EXC(regs)	(((regs)->trap & 2) != 0)
 #define IS_MCHECK_EXC(regs)	(((regs)->trap & 4) != 0)
+#define IS_DEBUG_EXC(regs)	(((regs)->trap & 8) != 0)
 #endif /* ! __powerpc64__ */
 #define TRAP(regs)		((regs)->trap & ~0xF)
 #ifdef __powerpc64__