kprobes: Use RCU in all users of __module_text_address().

__module_text_address() can be invoked within a RCU section, there is no
requirement to have preemption disabled.

Replace the preempt_disable() section around __module_text_address()
with RCU.

Cc: David S. Miller <[email protected]>
Cc: Anil S Keshavamurthy <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Naveen N Rao <[email protected]>
Cc: [email protected]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Petr Pavlu <[email protected]>

Author: Sebastian Andrzej Siewior

kernel/kprobes.c

@@ -1547,7 +1547,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
 	/* Ensure the address is in a text area, and find a module if exists. */
 	*probed_mod = NULL;
 	if (!core_kernel_text((unsigned long) p->addr)) {
-		guard(preempt)();
+		guard(rcu)();
 		*probed_mod = __module_text_address((unsigned long) p->addr);
 		if (!(*probed_mod))
 			return -EINVAL;