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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 *
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.
11 */
12
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/kprobes.h>
16
17/* For each probe you need to allocate a kprobe structure */
18static struct kprobe kp = {
19 .symbol_name = "do_fork",
20};
21
22/* kprobe pre_handler: called just before the probed instruction is executed */
23static int handler_pre(struct kprobe *p, struct pt_regs *regs)
24{
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
40
41 /* A dump_stack() here will give a stack backtrace */
42 return 0;
43}
44
45/* kprobe post_handler: called after the probed instruction is executed */
46static void handler_post(struct kprobe *p, struct pt_regs *regs,
47 unsigned long flags)
48{
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
61}
62
63/*
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.
67 */
68static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
69{
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;
74}
75
76static int __init kprobe_init(void)
77{
78 int ret;
79 kp.pre_handler = handler_pre;
80 kp.post_handler = handler_post;
81 kp.fault_handler = handler_fault;
82
83 ret = register_kprobe(&kp);
84 if (ret < 0) {
85 printk(KERN_INFO "register_kprobe failed, returned %d\n", ret);
86 return ret;
87 }
88 printk(KERN_INFO "Planted kprobe at %p\n", kp.addr);
89 return 0;
90}
91
92static void __exit kprobe_exit(void)
93{
94 unregister_kprobe(&kp);
95 printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr);
96}
97
98module_init(kprobe_init)
99module_exit(kprobe_exit)
100MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * NOTE: This example is works on x86 and powerpc.
4 * Here's a sample kernel module showing the use of kprobes to dump a
5 * stack trace and selected registers when _do_fork() is called.
6 *
7 * For more information on theory of operation of kprobes, see
8 * Documentation/kprobes.txt
9 *
10 * You will see the trace data in /var/log/messages and on the console
11 * whenever _do_fork() is invoked to create a new process.
12 */
13
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/kprobes.h>
17
18#define MAX_SYMBOL_LEN 64
19static char symbol[MAX_SYMBOL_LEN] = "_do_fork";
20module_param_string(symbol, symbol, sizeof(symbol), 0644);
21
22/* For each probe you need to allocate a kprobe structure */
23static struct kprobe kp = {
24 .symbol_name = symbol,
25};
26
27/* kprobe pre_handler: called just before the probed instruction is executed */
28static int handler_pre(struct kprobe *p, struct pt_regs *regs)
29{
30#ifdef CONFIG_X86
31 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
35 pr_info("<%s> pre_handler: p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n",
36 p->symbol_name, p->addr, regs->nip, regs->msr);
37#endif
38#ifdef CONFIG_MIPS
39 pr_info("<%s> pre_handler: p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n",
40 p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status);
41#endif
42#ifdef CONFIG_ARM64
43 pr_info("<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx,"
44 " pstate = 0x%lx\n",
45 p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate);
46#endif
47#ifdef CONFIG_S390
48 pr_info("<%s> pre_handler: p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",
49 p->symbol_name, p->addr, regs->psw.addr, regs->flags);
50#endif
51
52 /* A dump_stack() here will give a stack backtrace */
53 return 0;
54}
55
56/* kprobe post_handler: called after the probed instruction is executed */
57static void handler_post(struct kprobe *p, struct pt_regs *regs,
58 unsigned long flags)
59{
60#ifdef CONFIG_X86
61 pr_info("<%s> post_handler: p->addr = 0x%p, flags = 0x%lx\n",
62 p->symbol_name, p->addr, regs->flags);
63#endif
64#ifdef CONFIG_PPC
65 pr_info("<%s> post_handler: p->addr = 0x%p, msr = 0x%lx\n",
66 p->symbol_name, p->addr, regs->msr);
67#endif
68#ifdef CONFIG_MIPS
69 pr_info("<%s> post_handler: p->addr = 0x%p, status = 0x%lx\n",
70 p->symbol_name, p->addr, regs->cp0_status);
71#endif
72#ifdef CONFIG_ARM64
73 pr_info("<%s> post_handler: p->addr = 0x%p, pstate = 0x%lx\n",
74 p->symbol_name, p->addr, (long)regs->pstate);
75#endif
76#ifdef CONFIG_S390
77 pr_info("<%s> pre_handler: p->addr, 0x%p, flags = 0x%lx\n",
78 p->symbol_name, p->addr, regs->flags);
79#endif
80}
81
82/*
83 * fault_handler: this is called if an exception is generated for any
84 * instruction within the pre- or post-handler, or when Kprobes
85 * single-steps the probed instruction.
86 */
87static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
88{
89 pr_info("fault_handler: p->addr = 0x%p, trap #%dn", p->addr, trapnr);
90 /* Return 0 because we don't handle the fault. */
91 return 0;
92}
93
94static int __init kprobe_init(void)
95{
96 int ret;
97 kp.pre_handler = handler_pre;
98 kp.post_handler = handler_post;
99 kp.fault_handler = handler_fault;
100
101 ret = register_kprobe(&kp);
102 if (ret < 0) {
103 pr_err("register_kprobe failed, returned %d\n", ret);
104 return ret;
105 }
106 pr_info("Planted kprobe at %p\n", kp.addr);
107 return 0;
108}
109
110static void __exit kprobe_exit(void)
111{
112 unregister_kprobe(&kp);
113 pr_info("kprobe at %p unregistered\n", kp.addr);
114}
115
116module_init(kprobe_init)
117module_exit(kprobe_exit)
118MODULE_LICENSE("GPL");