kprobe_example.c (e82a82c19f4272ea5437cc76e5711b98e2ee6223) kprobe_example.c (e708c1488bca54b901c4c3e73462ab2decdb8209)
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.
5 *
6 * For more information on theory of operation of kprobes, see
7 * Documentation/kprobes.txt
8 *

--- 13 unchanged lines hidden (view full) ---

22static struct kprobe kp = {
23 .symbol_name = symbol,
24};
25
26/* kprobe pre_handler: called just before the probed instruction is executed */
27static int handler_pre(struct kprobe *p, struct pt_regs *regs)
28{
29#ifdef CONFIG_X86
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.
5 *
6 * For more information on theory of operation of kprobes, see
7 * Documentation/kprobes.txt
8 *

--- 13 unchanged lines hidden (view full) ---

22static struct kprobe kp = {
23 .symbol_name = symbol,
24};
25
26/* kprobe pre_handler: called just before the probed instruction is executed */
27static int handler_pre(struct kprobe *p, struct pt_regs *regs)
28{
29#ifdef CONFIG_X86
30 printk(KERN_INFO "<%s> pre_handler: p->addr = 0x%p, ip = %lx,"
31 " flags = 0x%lx\n",
30 pr_info("<%s> pre_handler: p->addr = 0x%p, ip = %lx, flags = 0x%lx\n",
32 p->symbol_name, p->addr, regs->ip, regs->flags);
33#endif
34#ifdef CONFIG_PPC
31 p->symbol_name, p->addr, regs->ip, regs->flags);
32#endif
33#ifdef CONFIG_PPC
35 printk(KERN_INFO "<%s> pre_handler: p->addr = 0x%p, nip = 0x%lx,"
36 " msr = 0x%lx\n",
34 pr_info("<%s> pre_handler: p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n",
37 p->symbol_name, p->addr, regs->nip, regs->msr);
38#endif
39#ifdef CONFIG_MIPS
35 p->symbol_name, p->addr, regs->nip, regs->msr);
36#endif
37#ifdef CONFIG_MIPS
40 printk(KERN_INFO "<%s> pre_handler: p->addr = 0x%p, epc = 0x%lx,"
41 " status = 0x%lx\n",
38 pr_info("<%s> pre_handler: p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n",
42 p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status);
43#endif
44#ifdef CONFIG_TILEGX
39 p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status);
40#endif
41#ifdef CONFIG_TILEGX
45 printk(KERN_INFO "<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx,"
46 " ex1 = 0x%lx\n",
42 pr_info("<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx, ex1 = 0x%lx\n",
47 p->symbol_name, p->addr, regs->pc, regs->ex1);
48#endif
43 p->symbol_name, p->addr, regs->pc, regs->ex1);
44#endif
45#ifdef CONFIG_ARM64
46 pr_info("<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx,"
47 " pstate = 0x%lx\n",
48 p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate);
49#endif
49
50 /* A dump_stack() here will give a stack backtrace */
51 return 0;
52}
53
54/* kprobe post_handler: called after the probed instruction is executed */
55static void handler_post(struct kprobe *p, struct pt_regs *regs,
56 unsigned long flags)
57{
58#ifdef CONFIG_X86
50
51 /* A dump_stack() here will give a stack backtrace */
52 return 0;
53}
54
55/* kprobe post_handler: called after the probed instruction is executed */
56static void handler_post(struct kprobe *p, struct pt_regs *regs,
57 unsigned long flags)
58{
59#ifdef CONFIG_X86
59 printk(KERN_INFO "<%s> post_handler: p->addr = 0x%p, flags = 0x%lx\n",
60 pr_info("<%s> post_handler: p->addr = 0x%p, flags = 0x%lx\n",
60 p->symbol_name, p->addr, regs->flags);
61#endif
62#ifdef CONFIG_PPC
61 p->symbol_name, p->addr, regs->flags);
62#endif
63#ifdef CONFIG_PPC
63 printk(KERN_INFO "<%s> post_handler: p->addr = 0x%p, msr = 0x%lx\n",
64 pr_info("<%s> post_handler: p->addr = 0x%p, msr = 0x%lx\n",
64 p->symbol_name, p->addr, regs->msr);
65#endif
66#ifdef CONFIG_MIPS
65 p->symbol_name, p->addr, regs->msr);
66#endif
67#ifdef CONFIG_MIPS
67 printk(KERN_INFO "<%s> post_handler: p->addr = 0x%p, status = 0x%lx\n",
68 pr_info("<%s> post_handler: p->addr = 0x%p, status = 0x%lx\n",
68 p->symbol_name, p->addr, regs->cp0_status);
69#endif
70#ifdef CONFIG_TILEGX
69 p->symbol_name, p->addr, regs->cp0_status);
70#endif
71#ifdef CONFIG_TILEGX
71 printk(KERN_INFO "<%s> post_handler: p->addr = 0x%p, ex1 = 0x%lx\n",
72 pr_info("<%s> post_handler: p->addr = 0x%p, ex1 = 0x%lx\n",
72 p->symbol_name, p->addr, regs->ex1);
73#endif
73 p->symbol_name, p->addr, regs->ex1);
74#endif
75#ifdef CONFIG_ARM64
76 pr_info("<%s> post_handler: p->addr = 0x%p, pstate = 0x%lx\n",
77 p->symbol_name, p->addr, (long)regs->pstate);
78#endif
74}
75
76/*
77 * fault_handler: this is called if an exception is generated for any
78 * instruction within the pre- or post-handler, or when Kprobes
79 * single-steps the probed instruction.
80 */
81static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
82{
79}
80
81/*
82 * fault_handler: this is called if an exception is generated for any
83 * instruction within the pre- or post-handler, or when Kprobes
84 * single-steps the probed instruction.
85 */
86static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
87{
83 printk(KERN_INFO "fault_handler: p->addr = 0x%p, trap #%dn",
84 p->addr, trapnr);
88 pr_info("fault_handler: p->addr = 0x%p, trap #%dn", p->addr, trapnr);
85 /* Return 0 because we don't handle the fault. */
86 return 0;
87}
88
89static int __init kprobe_init(void)
90{
91 int ret;
92 kp.pre_handler = handler_pre;
93 kp.post_handler = handler_post;
94 kp.fault_handler = handler_fault;
95
96 ret = register_kprobe(&kp);
97 if (ret < 0) {
89 /* Return 0 because we don't handle the fault. */
90 return 0;
91}
92
93static int __init kprobe_init(void)
94{
95 int ret;
96 kp.pre_handler = handler_pre;
97 kp.post_handler = handler_post;
98 kp.fault_handler = handler_fault;
99
100 ret = register_kprobe(&kp);
101 if (ret < 0) {
98 printk(KERN_INFO "register_kprobe failed, returned %d\n", ret);
102 pr_err("register_kprobe failed, returned %d\n", ret);
99 return ret;
100 }
103 return ret;
104 }
101 printk(KERN_INFO "Planted kprobe at %p\n", kp.addr);
105 pr_info("Planted kprobe at %p\n", kp.addr);
102 return 0;
103}
104
105static void __exit kprobe_exit(void)
106{
107 unregister_kprobe(&kp);
106 return 0;
107}
108
109static void __exit kprobe_exit(void)
110{
111 unregister_kprobe(&kp);
108 printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr);
112 pr_info("kprobe at %p unregistered\n", kp.addr);
109}
110
111module_init(kprobe_init)
112module_exit(kprobe_exit)
113MODULE_LICENSE("GPL");
113}
114
115module_init(kprobe_init)
116module_exit(kprobe_exit)
117MODULE_LICENSE("GPL");