kprobes: Prohibit to probe native_get_debugreg

Since do_debug() calls get_debugreg(), native_get_debugreg() will be
called from singlestepping. This can cause an int3 infinite loop.

We can't put it in the .text.kprobes section because it is inlined,
then we blacklist its name.

Signed-off-by: Masami Hiramatsu <[email protected]>
Acked-by: Ananth N Mavinakayanahalli <[email protected]>
Cc: Ingo Molnar <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

kernel/kprobes.c

@@ -90,6 +90,7 @@ static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
  */
 static struct kprobe_blackpoint kprobe_blacklist[] = {
 	{"preempt_schedule",},
+	{"native_get_debugreg",},
 	{NULL}    /* Terminator */
 };