LoongArch: ftrace: 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: Huacai Chen <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: WANG Xuerui <[email protected]>
Cc: [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

arch/loongarch/kernel/ftrace_dyn.c

@@ -85,14 +85,13 @@ static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, struct module *mod
 	 * dealing with an out-of-range condition, we can assume it
 	 * is due to a module being loaded far away from the kernel.
 	 *
-	 * NOTE: __module_text_address() must be called with preemption
-	 * disabled, but we can rely on ftrace_lock to ensure that 'mod'
+	 * NOTE: __module_text_address() must be called within a RCU read
+	 * section, but we can rely on ftrace_lock to ensure that 'mod'
 	 * retains its validity throughout the remainder of this code.
 	 */
 	if (!mod) {
-		preempt_disable();
-		mod = __module_text_address(pc);
-		preempt_enable();
+		scoped_guard(rcu)
+			mod = __module_text_address(pc);
 	}
 
 	if (WARN_ON(!mod))