Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 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 |
Petr Mladek | 54aea45 | 2015-10-01 15:37:11 -0700 | [diff] [blame] | 4 | * stack trace and selected registers when _do_fork() is called. |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 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 |
Petr Mladek | 54aea45 | 2015-10-01 15:37:11 -0700 | [diff] [blame] | 10 | * whenever _do_fork() is invoked to create a new process. |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 11 | */ |
| 12 | |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/kprobes.h> |
| 16 | |
Huang Shijie | d04659a | 2016-05-20 17:04:33 -0700 | [diff] [blame] | 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 | |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 21 | /* For each probe you need to allocate a kprobe structure */ |
| 22 | static struct kprobe kp = { |
Huang Shijie | d04659a | 2016-05-20 17:04:33 -0700 | [diff] [blame] | 23 | .symbol_name = symbol, |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 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 |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 30 | printk(KERN_INFO "<%s> pre_handler: p->addr = 0x%p, ip = %lx," |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 31 | " flags = 0x%lx\n", |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 32 | p->symbol_name, p->addr, regs->ip, regs->flags); |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 33 | #endif |
| 34 | #ifdef CONFIG_PPC |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 35 | printk(KERN_INFO "<%s> pre_handler: p->addr = 0x%p, nip = 0x%lx," |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 36 | " msr = 0x%lx\n", |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 37 | p->symbol_name, p->addr, regs->nip, regs->msr); |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 38 | #endif |
David Daney | 8a14923 | 2010-08-03 11:22:21 -0700 | [diff] [blame] | 39 | #ifdef CONFIG_MIPS |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 40 | printk(KERN_INFO "<%s> pre_handler: p->addr = 0x%p, epc = 0x%lx," |
David Daney | 8a14923 | 2010-08-03 11:22:21 -0700 | [diff] [blame] | 41 | " status = 0x%lx\n", |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 42 | p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status); |
David Daney | 8a14923 | 2010-08-03 11:22:21 -0700 | [diff] [blame] | 43 | #endif |
Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 44 | #ifdef CONFIG_TILEGX |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 45 | printk(KERN_INFO "<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx," |
Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 46 | " ex1 = 0x%lx\n", |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 47 | p->symbol_name, p->addr, regs->pc, regs->ex1); |
Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 48 | #endif |
Sandeepa Prabhu | af78ced | 2016-07-08 12:35:54 -0400 | [diff] [blame^] | 49 | #ifdef CONFIG_ARM64 |
| 50 | pr_info("<%s> pre_handler: p->addr = 0x%p, pc = 0x%lx," |
| 51 | " pstate = 0x%lx\n", |
| 52 | p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate); |
| 53 | #endif |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 54 | |
| 55 | /* A dump_stack() here will give a stack backtrace */ |
| 56 | return 0; |
| 57 | } |
| 58 | |
| 59 | /* kprobe post_handler: called after the probed instruction is executed */ |
| 60 | static void handler_post(struct kprobe *p, struct pt_regs *regs, |
| 61 | unsigned long flags) |
| 62 | { |
| 63 | #ifdef CONFIG_X86 |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 64 | printk(KERN_INFO "<%s> post_handler: p->addr = 0x%p, flags = 0x%lx\n", |
| 65 | p->symbol_name, p->addr, regs->flags); |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 66 | #endif |
| 67 | #ifdef CONFIG_PPC |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 68 | printk(KERN_INFO "<%s> post_handler: p->addr = 0x%p, msr = 0x%lx\n", |
| 69 | p->symbol_name, p->addr, regs->msr); |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 70 | #endif |
David Daney | 8a14923 | 2010-08-03 11:22:21 -0700 | [diff] [blame] | 71 | #ifdef CONFIG_MIPS |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 72 | printk(KERN_INFO "<%s> post_handler: p->addr = 0x%p, status = 0x%lx\n", |
| 73 | p->symbol_name, p->addr, regs->cp0_status); |
David Daney | 8a14923 | 2010-08-03 11:22:21 -0700 | [diff] [blame] | 74 | #endif |
Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 75 | #ifdef CONFIG_TILEGX |
Huang Shijie | ea9b501 | 2016-05-20 17:04:36 -0700 | [diff] [blame] | 76 | printk(KERN_INFO "<%s> post_handler: p->addr = 0x%p, ex1 = 0x%lx\n", |
| 77 | p->symbol_name, p->addr, regs->ex1); |
Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 78 | #endif |
Sandeepa Prabhu | af78ced | 2016-07-08 12:35:54 -0400 | [diff] [blame^] | 79 | #ifdef CONFIG_ARM64 |
| 80 | pr_info("<%s> post_handler: p->addr = 0x%p, pstate = 0x%lx\n", |
| 81 | p->symbol_name, p->addr, (long)regs->pstate); |
| 82 | #endif |
Ananth N Mavinakayanahalli | 804defe | 2008-03-04 14:28:38 -0800 | [diff] [blame] | 83 | } |
| 84 | |
| 85 | /* |
| 86 | * fault_handler: this is called if an exception is generated for any |
| 87 | * instruction within the pre- or post-handler, or when Kprobes |
| 88 | * single-steps the probed instruction. |
| 89 | */ |
| 90 | static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr) |
| 91 | { |
| 92 | printk(KERN_INFO "fault_handler: p->addr = 0x%p, trap #%dn", |
| 93 | p->addr, trapnr); |
| 94 | /* Return 0 because we don't handle the fault. */ |
| 95 | return 0; |
| 96 | } |
| 97 | |
| 98 | static int __init kprobe_init(void) |
| 99 | { |
| 100 | int ret; |
| 101 | kp.pre_handler = handler_pre; |
| 102 | kp.post_handler = handler_post; |
| 103 | kp.fault_handler = handler_fault; |
| 104 | |
| 105 | ret = register_kprobe(&kp); |
| 106 | if (ret < 0) { |
| 107 | printk(KERN_INFO "register_kprobe failed, returned %d\n", ret); |
| 108 | return ret; |
| 109 | } |
| 110 | printk(KERN_INFO "Planted kprobe at %p\n", kp.addr); |
| 111 | return 0; |
| 112 | } |
| 113 | |
| 114 | static void __exit kprobe_exit(void) |
| 115 | { |
| 116 | unregister_kprobe(&kp); |
| 117 | printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr); |
| 118 | } |
| 119 | |
| 120 | module_init(kprobe_init) |
| 121 | module_exit(kprobe_exit) |
| 122 | MODULE_LICENSE("GPL"); |