blob: b7541355b92bd547c27faa21ac6a01a2b96cbc85 [file] [log] [blame]
* Here's a sample kernel module showing the use of jprobes to dump
* the arguments of do_fork().
* For more information on theory of operation of jprobes, see
* Documentation/kprobes.txt
* Build and insert the kernel module as done in the kprobe example.
* You will see the trace data in /var/log/messages and on the
* console whenever do_fork() is invoked to create a new process.
* (Some messages may be suppressed if syslogd is configured to
* eliminate duplicate messages.)
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kprobes.h>
* Jumper probe for do_fork.
* Mirror principle enables access to arguments of the probed routine
* from the probe handler.
/* Proxy routine having the same arguments as actual do_fork() routine */
static long jdo_fork(unsigned long clone_flags, unsigned long stack_start,
struct pt_regs *regs, unsigned long stack_size,
int __user *parent_tidptr, int __user *child_tidptr)
printk(KERN_INFO "jprobe: clone_flags = 0x%lx, stack_size = 0x%lx,"
" regs = 0x%p\n",
clone_flags, stack_size, regs);
/* Always end with a call to jprobe_return(). */
return 0;
static struct jprobe my_jprobe = {
.entry = jdo_fork,
.kp = {
.symbol_name = "do_fork",
static int __init jprobe_init(void)
int ret;
ret = register_jprobe(&my_jprobe);
if (ret < 0) {
printk(KERN_INFO "register_jprobe failed, returned %d\n", ret);
return -1;
printk(KERN_INFO "Planted jprobe at %p, handler addr %p\n",, my_jprobe.entry);
return 0;
static void __exit jprobe_exit(void)
printk(KERN_INFO "jprobe at %p unregistered\n",;