1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/module.h>
3 #include <linux/kthread.h>
4 #include <linux/ftrace.h>
6 void my_direct_func1(void)
8 trace_printk("my direct func1\n");
11 void my_direct_func2(void)
13 trace_printk("my direct func2\n");
16 extern void my_tramp1(void *);
17 extern void my_tramp2(void *);
19 static unsigned long my_ip = (unsigned long)schedule;
22 " .pushsection .text, \"ax\", @progbits\n"
26 " call my_direct_func1\n"
32 " call my_direct_func2\n"
38 static unsigned long my_tramp = (unsigned long)my_tramp1;
39 static unsigned long tramps[2] = {
40 (unsigned long)my_tramp1,
41 (unsigned long)my_tramp2,
44 static int simple_thread(void *arg)
49 while (!kthread_should_stop()) {
50 set_current_state(TASK_INTERRUPTIBLE);
51 schedule_timeout(2 * HZ);
56 ret = modify_ftrace_direct(my_ip, my_tramp, tramps[t]);
65 static struct task_struct *simple_tsk;
67 static int __init ftrace_direct_init(void)
71 ret = register_ftrace_direct(my_ip, my_tramp);
73 simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
77 static void __exit ftrace_direct_exit(void)
79 kthread_stop(simple_tsk);
80 unregister_ftrace_direct(my_ip, my_tramp);
83 module_init(ftrace_direct_init);
84 module_exit(ftrace_direct_exit);
86 MODULE_AUTHOR("Steven Rostedt");
87 MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()");
88 MODULE_LICENSE("GPL");