2 * Here's a sample kernel module showing the use of jprobes to dump
3 * the arguments of _do_fork().
5 * For more information on theory of operation of jprobes, see
6 * Documentation/kprobes.txt
8 * Build and insert the kernel module as done in the kprobe example.
9 * You will see the trace data in /var/log/messages and on the
10 * console whenever _do_fork() is invoked to create a new process.
11 * (Some messages may be suppressed if syslogd is configured to
12 * eliminate duplicate messages.)
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/kprobes.h>
20 * Jumper probe for _do_fork.
21 * Mirror principle enables access to arguments of the probed routine
22 * from the probe handler.
25 /* Proxy routine having the same arguments as actual _do_fork() routine */
26 static long j_do_fork(unsigned long clone_flags, unsigned long stack_start,
27 unsigned long stack_size, int __user *parent_tidptr,
28 int __user *child_tidptr)
30 pr_info("jprobe: clone_flags = 0x%lx, stack_start = 0x%lx "
31 "stack_size = 0x%lx\n", clone_flags, stack_start, stack_size);
33 /* Always end with a call to jprobe_return(). */
38 static struct jprobe my_jprobe = {
41 .symbol_name = "_do_fork",
45 static int __init jprobe_init(void)
49 ret = register_jprobe(&my_jprobe);
51 printk(KERN_INFO "register_jprobe failed, returned %d\n", ret);
54 printk(KERN_INFO "Planted jprobe at %p, handler addr %p\n",
55 my_jprobe.kp.addr, my_jprobe.entry);
59 static void __exit jprobe_exit(void)
61 unregister_jprobe(&my_jprobe);
62 printk(KERN_INFO "jprobe at %p unregistered\n", my_jprobe.kp.addr);
65 module_init(jprobe_init)
66 module_exit(jprobe_exit)
67 MODULE_LICENSE("GPL");