serial: amba-pl011: lock console writes against interrupts
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / samples / kprobes / kprobe_example.c
blobebf5e0c368ea0eb4bf48fbda2f76b5b347c3e247
1 /*
2 * NOTE: This example is works on x86 and powerpc.
3 * Here's a sample kernel module showing the use of kprobes to dump a
4 * stack trace and selected registers when do_fork() is called.
6 * For more information on theory of operation of kprobes, see
7 * Documentation/kprobes.txt
9 * You will see the trace data in /var/log/messages and on the console
10 * whenever do_fork() is invoked to create a new process.
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/kprobes.h>
17 /* For each probe you need to allocate a kprobe structure */
18 static struct kprobe kp = {
19 .symbol_name = "do_fork",
22 /* kprobe pre_handler: called just before the probed instruction is executed */
23 static int handler_pre(struct kprobe *p, struct pt_regs *regs)
25 #ifdef CONFIG_X86
26 printk(KERN_INFO "pre_handler: p->addr = 0x%p, ip = %lx,"
27 " flags = 0x%lx\n",
28 p->addr, regs->ip, regs->flags);
29 #endif
30 #ifdef CONFIG_PPC
31 printk(KERN_INFO "pre_handler: p->addr = 0x%p, nip = 0x%lx,"
32 " msr = 0x%lx\n",
33 p->addr, regs->nip, regs->msr);
34 #endif
35 #ifdef CONFIG_MIPS
36 printk(KERN_INFO "pre_handler: p->addr = 0x%p, epc = 0x%lx,"
37 " status = 0x%lx\n",
38 p->addr, regs->cp0_epc, regs->cp0_status);
39 #endif
41 /* A dump_stack() here will give a stack backtrace */
42 return 0;
45 /* kprobe post_handler: called after the probed instruction is executed */
46 static void handler_post(struct kprobe *p, struct pt_regs *regs,
47 unsigned long flags)
49 #ifdef CONFIG_X86
50 printk(KERN_INFO "post_handler: p->addr = 0x%p, flags = 0x%lx\n",
51 p->addr, regs->flags);
52 #endif
53 #ifdef CONFIG_PPC
54 printk(KERN_INFO "post_handler: p->addr = 0x%p, msr = 0x%lx\n",
55 p->addr, regs->msr);
56 #endif
57 #ifdef CONFIG_MIPS
58 printk(KERN_INFO "post_handler: p->addr = 0x%p, status = 0x%lx\n",
59 p->addr, regs->cp0_status);
60 #endif
64 * fault_handler: this is called if an exception is generated for any
65 * instruction within the pre- or post-handler, or when Kprobes
66 * single-steps the probed instruction.
68 static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
70 printk(KERN_INFO "fault_handler: p->addr = 0x%p, trap #%dn",
71 p->addr, trapnr);
72 /* Return 0 because we don't handle the fault. */
73 return 0;
76 static int __init kprobe_init(void)
78 int ret;
79 kp.pre_handler = handler_pre;
80 kp.post_handler = handler_post;
81 kp.fault_handler = handler_fault;
83 ret = register_kprobe(&kp);
84 if (ret < 0) {
85 printk(KERN_INFO "register_kprobe failed, returned %d\n", ret);
86 return ret;
88 printk(KERN_INFO "Planted kprobe at %p\n", kp.addr);
89 return 0;
92 static void __exit kprobe_exit(void)
94 unregister_kprobe(&kp);
95 printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr);
98 module_init(kprobe_init)
99 module_exit(kprobe_exit)
100 MODULE_LICENSE("GPL");