ftrace_set_early_filter
ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable);
ftrace_set_early_filter(&global_ops, ftrace_filter_buf, 1);
ftrace_set_early_filter(&global_ops, ftrace_notrace_buf, 0);
ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);