sh: Don't NOTIFY_STOP for non-UBC breakpoint traps.

Presently the hw_breakpoint code is the primary notifier dispatch for
breakpoint traps, although it's only UBC traps that are of particular
interest there. This patches in a check to allow non-UBC generated
breakpoints to pass through down the remainder of the notifier chain,
giving things like kgdb a chance at getting notified.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/hw_breakpoint.c

@@ -398,9 +398,18 @@ BUILD_TRAP_HANDLER(breakpoint)
 int __kprobes hw_breakpoint_exceptions_notify(struct notifier_block *unused,
 				    unsigned long val, void *data)
 {
+	struct die_args *args = data;
+
 	if (val != DIE_BREAKPOINT)
 		return NOTIFY_DONE;
 
+	/*
+	 * If the breakpoint hasn't been triggered by the UBC, it's
+	 * probably from a debugger, so don't do anything more here.
+	 */
+	if (args->trapnr != 0x1e0)
+		return NOTIFY_DONE;
+
 	return hw_breakpoint_handler(data);
 }