Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Here's a sample kernel module showing the use of kprobes to dump a
4 * stack trace and selected registers when kernel_clone() is called.
5 *
6 * For more information on theory of operation of kprobes, see
7 * Documentation/trace/kprobes.rst
8 *
9 * You will see the trace data in /var/log/messages and on the console
10 * whenever kernel_clone() is invoked to create a new process.
11 */
12
13#define pr_fmt(fmt) "%s: " fmt, __func__
14
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/kprobes.h>
18
19static char symbol[KSYM_NAME_LEN] = "kernel_clone";
20module_param_string(symbol, symbol, KSYM_NAME_LEN, 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 __kprobes handler_pre(struct kprobe *p, struct pt_regs *regs)
29{
30#ifdef CONFIG_X86
31 pr_info("<%s> 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> 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> 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> p->addr = 0x%p, pc = 0x%lx, pstate = 0x%lx\n",
44 p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate);
45#endif
46#ifdef CONFIG_ARM
47 pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, cpsr = 0x%lx\n",
48 p->symbol_name, p->addr, (long)regs->ARM_pc, (long)regs->ARM_cpsr);
49#endif
50#ifdef CONFIG_RISCV
51 pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, status = 0x%lx\n",
52 p->symbol_name, p->addr, regs->epc, regs->status);
53#endif
54#ifdef CONFIG_S390
55 pr_info("<%s> p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",
56 p->symbol_name, p->addr, regs->psw.addr, regs->flags);
57#endif
58#ifdef CONFIG_LOONGARCH
59 pr_info("<%s> p->addr = 0x%p, era = 0x%lx, estat = 0x%lx\n",
60 p->symbol_name, p->addr, regs->csr_era, regs->csr_estat);
61#endif
62
63 /* A dump_stack() here will give a stack backtrace */
64 return 0;
65}
66
67/* kprobe post_handler: called after the probed instruction is executed */
68static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,
69 unsigned long flags)
70{
71#ifdef CONFIG_X86
72 pr_info("<%s> p->addr = 0x%p, flags = 0x%lx\n",
73 p->symbol_name, p->addr, regs->flags);
74#endif
75#ifdef CONFIG_PPC
76 pr_info("<%s> p->addr = 0x%p, msr = 0x%lx\n",
77 p->symbol_name, p->addr, regs->msr);
78#endif
79#ifdef CONFIG_MIPS
80 pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
81 p->symbol_name, p->addr, regs->cp0_status);
82#endif
83#ifdef CONFIG_ARM64
84 pr_info("<%s> p->addr = 0x%p, pstate = 0x%lx\n",
85 p->symbol_name, p->addr, (long)regs->pstate);
86#endif
87#ifdef CONFIG_ARM
88 pr_info("<%s> p->addr = 0x%p, cpsr = 0x%lx\n",
89 p->symbol_name, p->addr, (long)regs->ARM_cpsr);
90#endif
91#ifdef CONFIG_RISCV
92 pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
93 p->symbol_name, p->addr, regs->status);
94#endif
95#ifdef CONFIG_S390
96 pr_info("<%s> p->addr, 0x%p, flags = 0x%lx\n",
97 p->symbol_name, p->addr, regs->flags);
98#endif
99#ifdef CONFIG_LOONGARCH
100 pr_info("<%s> p->addr = 0x%p, estat = 0x%lx\n",
101 p->symbol_name, p->addr, regs->csr_estat);
102#endif
103}
104
105static int __init kprobe_init(void)
106{
107 int ret;
108 kp.pre_handler = handler_pre;
109 kp.post_handler = handler_post;
110
111 ret = register_kprobe(&kp);
112 if (ret < 0) {
113 pr_err("register_kprobe failed, returned %d\n", ret);
114 return ret;
115 }
116 pr_info("Planted kprobe at %p\n", kp.addr);
117 return 0;
118}
119
120static void __exit kprobe_exit(void)
121{
122 unregister_kprobe(&kp);
123 pr_info("kprobe at %p unregistered\n", kp.addr);
124}
125
126module_init(kprobe_init)
127module_exit(kprobe_exit)
128MODULE_DESCRIPTION("sample kernel module showing the use of kprobes");
129MODULE_LICENSE("GPL");
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#ifdef CONFIG_TILEGX
41 printk(KERN_INFO "pre_handler: p->addr = 0x%p, pc = 0x%lx,"
42 " ex1 = 0x%lx\n",
43 p->addr, regs->pc, regs->ex1);
44#endif
45
46 /* A dump_stack() here will give a stack backtrace */
47 return 0;
48}
49
50/* kprobe post_handler: called after the probed instruction is executed */
51static void handler_post(struct kprobe *p, struct pt_regs *regs,
52 unsigned long flags)
53{
54#ifdef CONFIG_X86
55 printk(KERN_INFO "post_handler: p->addr = 0x%p, flags = 0x%lx\n",
56 p->addr, regs->flags);
57#endif
58#ifdef CONFIG_PPC
59 printk(KERN_INFO "post_handler: p->addr = 0x%p, msr = 0x%lx\n",
60 p->addr, regs->msr);
61#endif
62#ifdef CONFIG_MIPS
63 printk(KERN_INFO "post_handler: p->addr = 0x%p, status = 0x%lx\n",
64 p->addr, regs->cp0_status);
65#endif
66#ifdef CONFIG_TILEGX
67 printk(KERN_INFO "post_handler: p->addr = 0x%p, ex1 = 0x%lx\n",
68 p->addr, regs->ex1);
69#endif
70}
71
72/*
73 * fault_handler: this is called if an exception is generated for any
74 * instruction within the pre- or post-handler, or when Kprobes
75 * single-steps the probed instruction.
76 */
77static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
78{
79 printk(KERN_INFO "fault_handler: p->addr = 0x%p, trap #%dn",
80 p->addr, trapnr);
81 /* Return 0 because we don't handle the fault. */
82 return 0;
83}
84
85static int __init kprobe_init(void)
86{
87 int ret;
88 kp.pre_handler = handler_pre;
89 kp.post_handler = handler_post;
90 kp.fault_handler = handler_fault;
91
92 ret = register_kprobe(&kp);
93 if (ret < 0) {
94 printk(KERN_INFO "register_kprobe failed, returned %d\n", ret);
95 return ret;
96 }
97 printk(KERN_INFO "Planted kprobe at %p\n", kp.addr);
98 return 0;
99}
100
101static void __exit kprobe_exit(void)
102{
103 unregister_kprobe(&kp);
104 printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr);
105}
106
107module_init(kprobe_init)
108module_exit(kprobe_exit)
109MODULE_LICENSE("GPL");