Commit | Line | Data |
---|---|---|
804defea AM |
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 | |
54aea454 | 4 | * stack trace and selected registers when _do_fork() is called. |
804defea AM |
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 | |
54aea454 | 10 | * whenever _do_fork() is invoked to create a new process. |
804defea AM |
11 | */ |
12 | ||
13 | #include <linux/kernel.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/kprobes.h> | |
16 | ||
d04659ac HS |
17 | #define MAX_SYMBOL_LEN 64 |
18 | static char symbol[MAX_SYMBOL_LEN] = "_do_fork"; | |
19 | module_param_string(symbol, symbol, sizeof(symbol), 0644); | |
20 | ||
804defea AM |
21 | /* For each probe you need to allocate a kprobe structure */ |
22 | static struct kprobe kp = { | |
d04659ac | 23 | .symbol_name = symbol, |
804defea AM |
24 | }; |
25 | ||
26 | /* kprobe pre_handler: called just before the probed instruction is executed */ | |
27 | static int handler_pre(struct kprobe *p, struct pt_regs *regs) | |
28 | { | |
29 | #ifdef CONFIG_X86 | |
e708c148 | 30 | pr_info("<%s> pre_handler: p->addr = 0x%p, ip = %lx, flags = 0x%lx\n", |
ea9b5013 | 31 | p->symbol_name, p->addr, regs->ip, regs->flags); |
804defea AM |
32 | #endif |
33 | #ifdef CONFIG_PPC | |
e708c148 | 34 | pr_info("<%s> pre_handler: p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n", |
ea9b5013 | 35 | p->symbol_name, p->addr, regs->nip, regs->msr); |
804defea | 36 | #endif |
8a149237 | 37 | #ifdef CONFIG_MIPS |
e708c148 | 38 | pr_info("<%s> pre_handler: p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n", |
ea9b5013 | 39 | p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status); |
8a149237 | 40 | #endif |
3fa17c39 | 41 | #ifdef CONFIG_TILEGX |
e708c148 | 42 | pr_info("<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx, ex1 = 0x%lx\n", |
ea9b5013 | 43 | p->symbol_name, p->addr, regs->pc, regs->ex1); |
3fa17c39 | 44 | #endif |
af78cede SP |
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 | |
804defea AM |
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 */ | |
56 | static void handler_post(struct kprobe *p, struct pt_regs *regs, | |
57 | unsigned long flags) | |
58 | { | |
59 | #ifdef CONFIG_X86 | |
e708c148 | 60 | pr_info("<%s> post_handler: p->addr = 0x%p, flags = 0x%lx\n", |
ea9b5013 | 61 | p->symbol_name, p->addr, regs->flags); |
804defea AM |
62 | #endif |
63 | #ifdef CONFIG_PPC | |
e708c148 | 64 | pr_info("<%s> post_handler: p->addr = 0x%p, msr = 0x%lx\n", |
ea9b5013 | 65 | p->symbol_name, p->addr, regs->msr); |
804defea | 66 | #endif |
8a149237 | 67 | #ifdef CONFIG_MIPS |
e708c148 | 68 | pr_info("<%s> post_handler: p->addr = 0x%p, status = 0x%lx\n", |
ea9b5013 | 69 | p->symbol_name, p->addr, regs->cp0_status); |
8a149237 | 70 | #endif |
3fa17c39 | 71 | #ifdef CONFIG_TILEGX |
e708c148 | 72 | pr_info("<%s> post_handler: p->addr = 0x%p, ex1 = 0x%lx\n", |
ea9b5013 | 73 | p->symbol_name, p->addr, regs->ex1); |
3fa17c39 | 74 | #endif |
af78cede SP |
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 | |
804defea AM |
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 | */ | |
86 | static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr) | |
87 | { | |
e708c148 | 88 | pr_info("fault_handler: p->addr = 0x%p, trap #%dn", p->addr, trapnr); |
804defea AM |
89 | /* Return 0 because we don't handle the fault. */ |
90 | return 0; | |
91 | } | |
92 | ||
93 | static 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) { | |
e708c148 | 102 | pr_err("register_kprobe failed, returned %d\n", ret); |
804defea AM |
103 | return ret; |
104 | } | |
e708c148 | 105 | pr_info("Planted kprobe at %p\n", kp.addr); |
804defea AM |
106 | return 0; |
107 | } | |
108 | ||
109 | static void __exit kprobe_exit(void) | |
110 | { | |
111 | unregister_kprobe(&kp); | |
e708c148 | 112 | pr_info("kprobe at %p unregistered\n", kp.addr); |
804defea AM |
113 | } |
114 | ||
115 | module_init(kprobe_init) | |
116 | module_exit(kprobe_exit) | |
117 | MODULE_LICENSE("GPL"); |