Commit | Line | Data |
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804defea AM |
1 | /* |
2 | * Here's a sample kernel module showing the use of jprobes to dump | |
3 | * the arguments of do_fork(). | |
4 | * | |
5 | * For more information on theory of operation of jprobes, see | |
6 | * Documentation/kprobes.txt | |
7 | * | |
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.) | |
13 | */ | |
14 | ||
15 | #include <linux/kernel.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/kprobes.h> | |
18 | ||
19 | /* | |
20 | * Jumper probe for do_fork. | |
21 | * Mirror principle enables access to arguments of the probed routine | |
22 | * from the probe handler. | |
23 | */ | |
24 | ||
25 | /* Proxy routine having the same arguments as actual do_fork() routine */ | |
26 | static long jdo_fork(unsigned long clone_flags, unsigned long stack_start, | |
27 | struct pt_regs *regs, unsigned long stack_size, | |
28 | int __user *parent_tidptr, int __user *child_tidptr) | |
29 | { | |
30 | printk(KERN_INFO "jprobe: clone_flags = 0x%lx, stack_size = 0x%lx," | |
31 | " regs = 0x%p\n", | |
32 | clone_flags, stack_size, regs); | |
33 | ||
34 | /* Always end with a call to jprobe_return(). */ | |
35 | jprobe_return(); | |
36 | return 0; | |
37 | } | |
38 | ||
39 | static struct jprobe my_jprobe = { | |
40 | .entry = jdo_fork, | |
41 | .kp = { | |
42 | .symbol_name = "do_fork", | |
43 | }, | |
44 | }; | |
45 | ||
46 | static int __init jprobe_init(void) | |
47 | { | |
48 | int ret; | |
49 | ||
50 | ret = register_jprobe(&my_jprobe); | |
51 | if (ret < 0) { | |
52 | printk(KERN_INFO "register_jprobe failed, returned %d\n", ret); | |
53 | return -1; | |
54 | } | |
55 | printk(KERN_INFO "Planted jprobe at %p, handler addr %p\n", | |
56 | my_jprobe.kp.addr, my_jprobe.entry); | |
57 | return 0; | |
58 | } | |
59 | ||
60 | static void __exit jprobe_exit(void) | |
61 | { | |
62 | unregister_jprobe(&my_jprobe); | |
63 | printk(KERN_INFO "jprobe at %p unregistered\n", my_jprobe.kp.addr); | |
64 | } | |
65 | ||
66 | module_init(jprobe_init) | |
67 | module_exit(jprobe_exit) | |
68 | MODULE_LICENSE("GPL"); |