ARM: 8770/1: kprobes: Prohibit probing on optimized_callback

BugLink: https://bugs.launchpad.net/bugs/1775477

commit 70948c05 upstream.

Prohibit probing on optimized_callback() because
it is called from kprobes itself. If we put a kprobes
on it, that will cause a recursive call loop.
Mark it NOKPROBE_SYMBOL.

Fixes: 0dc016db ("ARM: kprobes: enable OPTPROBES for ARM 32")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

arch/arm/probes/kprobes/opt-arm.c

@@ -192,6 +192,7 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
 
 	local_irq_restore(flags);
 }
+NOKPROBE_SYMBOL(optimized_callback)
 
 int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *orig)
 {