/*jprobes-sample.c */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kallsyms.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <asm/types.h>

/* 
 * Jumper probe for blockdev_direct_IO
 * Mirror principle enables access to arguments of the probed routine 
 * from the probe handler.
 */

long jdo_fork(unsigned long clone_flags, unsigned long stack_start, struct pt_regs *regs, unsigned long stack_size, int __user *parent_tidptr, int __user *child_tidptr)
{
	printk("In handler? \n");
	printk("jprobe: clone_flags=0x%x, stack_start=0x%x, stack_size=0x%x\n", clone_flags, stack_start, stack_size);
	jprobe_return(); 
	return 0;
}

static struct jprobe my_jprobe = {
	{.addr = (kprobe_opcode_t *)0xc011eb20}, 
	.entry = JPROBE_ENTRY(jdo_fork)
	//.entry = (kprobe_opcode_t *)jdo_fork
};

int init_module(void)
{
	int ret;

	/* first time invokation to initialize probe handler */
	printk("plant jprobe at %p, handler addr %p\n", 
		my_jprobe.kp.addr, my_jprobe.entry);
	/* now we are all set to register the probe */
	ret = register_jprobe(&my_jprobe);
	if (ret) {
		printk("Unable to register jprobe\n");
		return ret;
	}
		
	printk("registered jprobe\n");
	return 0;
}

void cleanup_module(void)
{
	unregister_jprobe(&my_jprobe);
	printk("jprobe unregistered\n");
}
MODULE_LICENSE("GPL");