/* * 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 	/* 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} /* * 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");