ARC: Fix the typo in event identifier flags used by ptrace

orig_r8_IS_EXCPN and orig_r8_IS_BRKPT were same values due to a
copy/paste error. Although it looks bad and is wrong, it really doesn't
affect gdb working.

orig_r8_IS_BRKPT is the one relevant to debugging (breakpoints), since
it is used to provide EFA vs. ERET to a ptrace "stop_pc" request.

So when gdb has inserted a breakpoint, orig_r8_IS_BRKPT is already set,
and anything else (i.e. orig_r8_IS_EXCPN) becoming same as it, really
doesn't hurt gdb. The corollary case, could be nasty but nobody uses the
ptrace "stop_pc" request in that case
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/entry.h

@@ -415,7 +415,7 @@
  *-------------------------------------------------------------*/
 .macro SAVE_ALL_EXCEPTION   marker
 
-	st      \marker, [sp, 8]
+	st      \marker, [sp, 8]	/* orig_r8 */
 	st      r0, [sp, 4]    /* orig_r0, needed only for sys calls */
 
 	/* Restore r9 used to code the early prologue */

arch/arc/include/asm/ptrace.h

@@ -123,7 +123,7 @@ static inline long regs_return_value(struct pt_regs *regs)
 #define orig_r8_IS_SCALL		0x0001
 #define orig_r8_IS_SCALL_RESTARTED	0x0002
 #define orig_r8_IS_BRKPT		0x0004
-#define orig_r8_IS_EXCPN		0x0004
+#define orig_r8_IS_EXCPN		0x0008
 #define orig_r8_IS_IRQ1			0x0010
 #define orig_r8_IS_IRQ2			0x0020
 

arch/arc/kernel/entry.S

@@ -452,7 +452,7 @@ tracesys:
 	; using ERET won't work since next-PC has already committed
 	lr  r12, [efa]
 	GET_CURR_TASK_FIELD_PTR   TASK_THREAD, r11
-	st  r12, [r11, THREAD_FAULT_ADDR]
+	st  r12, [r11, THREAD_FAULT_ADDR]	; thread.fault_address
 
 	; PRE Sys Call Ptrace hook
 	mov r0, sp			; pt_regs needed