kprobes: Introduce weak variant of kprobe_exceptions_notify()

kprobe_exceptions_notify() is not used on some of the architectures such
as arm[64] and powerpc anymore. Introduce a weak variant for such
architectures.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

kernel/kprobes.c

@@ -1705,6 +1705,12 @@ void unregister_kprobes(struct kprobe **kps, int num)
 }
 EXPORT_SYMBOL_GPL(unregister_kprobes);
 
+int __weak __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+					      unsigned long val, void *data)
+{
+	return NOTIFY_DONE;
+}
+
 static struct notifier_block kprobe_exceptions_nb = {
 	.notifier_call = kprobe_exceptions_notify,
 	.priority = 0x7fffffff /* we need to be notified first */