diff options
Diffstat (limited to 'kernel/samples/kprobes/kprobe_example.c')
| -rw-r--r-- | kernel/samples/kprobes/kprobe_example.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/kernel/samples/kprobes/kprobe_example.c b/kernel/samples/kprobes/kprobe_example.c new file mode 100644 index 000000000..366db1a9f --- /dev/null +++ b/kernel/samples/kprobes/kprobe_example.c @@ -0,0 +1,109 @@ +/* + * NOTE: This example is works on x86 and powerpc. + * Here's a sample kernel module showing the use of kprobes to dump a + * stack trace and selected registers when do_fork() is called. + * + * For more information on theory of operation of kprobes, see + * Documentation/kprobes.txt + * + * You will see the trace data in /var/log/messages and on the console + * whenever do_fork() is invoked to create a new process. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/kprobes.h> + +/* For each probe you need to allocate a kprobe structure */ +static struct kprobe kp = { + .symbol_name = "do_fork", +}; + +/* kprobe pre_handler: called just before the probed instruction is executed */ +static int handler_pre(struct kprobe *p, struct pt_regs *regs) +{ +#ifdef CONFIG_X86 + printk(KERN_INFO "pre_handler: p->addr = 0x%p, ip = %lx," + " flags = 0x%lx\n", + p->addr, regs->ip, regs->flags); +#endif +#ifdef CONFIG_PPC + printk(KERN_INFO "pre_handler: p->addr = 0x%p, nip = 0x%lx," + " msr = 0x%lx\n", + p->addr, regs->nip, regs->msr); +#endif +#ifdef CONFIG_MIPS + printk(KERN_INFO "pre_handler: p->addr = 0x%p, epc = 0x%lx," + " status = 0x%lx\n", + p->addr, regs->cp0_epc, regs->cp0_status); +#endif +#ifdef CONFIG_TILEGX + printk(KERN_INFO "pre_handler: p->addr = 0x%p, pc = 0x%lx," + " ex1 = 0x%lx\n", + p->addr, regs->pc, regs->ex1); +#endif + + /* A dump_stack() here will give a stack backtrace */ + return 0; +} + +/* kprobe post_handler: called after the probed instruction is executed */ +static void handler_post(struct kprobe *p, struct pt_regs *regs, + unsigned long flags) +{ +#ifdef CONFIG_X86 + printk(KERN_INFO "post_handler: p->addr = 0x%p, flags = 0x%lx\n", + p->addr, regs->flags); +#endif +#ifdef CONFIG_PPC + printk(KERN_INFO "post_handler: p->addr = 0x%p, msr = 0x%lx\n", + p->addr, regs->msr); +#endif +#ifdef CONFIG_MIPS + printk(KERN_INFO "post_handler: p->addr = 0x%p, status = 0x%lx\n", + p->addr, regs->cp0_status); +#endif +#ifdef CONFIG_TILEGX + printk(KERN_INFO "post_handler: p->addr = 0x%p, ex1 = 0x%lx\n", + p->addr, regs->ex1); +#endif +} + +/* + * fault_handler: this is called if an exception is generated for any + * instruction within the pre- or post-handler, or when Kprobes + * single-steps the probed instruction. + */ +static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr) +{ + printk(KERN_INFO "fault_handler: p->addr = 0x%p, trap #%dn", + p->addr, trapnr); + /* Return 0 because we don't handle the fault. */ + return 0; +} + +static int __init kprobe_init(void) +{ + int ret; + kp.pre_handler = handler_pre; + kp.post_handler = handler_post; + kp.fault_handler = handler_fault; + + ret = register_kprobe(&kp); + if (ret < 0) { + printk(KERN_INFO "register_kprobe failed, returned %d\n", ret); + return ret; + } + printk(KERN_INFO "Planted kprobe at %p\n", kp.addr); + return 0; +} + +static void __exit kprobe_exit(void) +{ + unregister_kprobe(&kp); + printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr); +} + +module_init(kprobe_init) +module_exit(kprobe_exit) +MODULE_LICENSE("GPL"); |