#include <linux/kdebug.h>
#include <linux/kprobes.h>
#include <linux/export.h>
#include <linux/notifier.h>
#include <linux/rcupdate.h>
#include <linux/vmalloc.h>
#include <linux/reboot.h>

BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);


static int notifier_chain_register(struct notifier_block **nl,
		struct notifier_block *n)
{
	while ((*nl) != NULL) {
		if (n->priority > (*nl)->priority)
			break;
		nl = &((*nl)->next);
	}
	n->next = *nl;
	rcu_assign_pointer(*nl, n);
	return 0;
}

static int notifier_chain_cond_register(struct notifier_block **nl,
		struct notifier_block *n)
{
	while ((*nl) != NULL) {
		if ((*nl) == n)
			return 0;
		if (n->priority > (*nl)->priority)
			break;
		nl = &((*nl)->next);
	}
	n->next = *nl;
	rcu_assign_pointer(*nl, n);
	return 0;
}

static int notifier_chain_unregister(struct notifier_block **nl,
		struct notifier_block *n)
{
	while ((*nl) != NULL) {
		if ((*nl) == n) {
			rcu_assign_pointer(*nl, n->next);
			return 0;
		}
		nl = &((*nl)->next);
	}
	return -ENOENT;
}

static int __kprobes notifier_call_chain(struct notifier_block **nl,
					unsigned long val, void *v,
					int nr_to_call,	int *nr_calls)
{
	int ret = NOTIFY_DONE;
	struct notifier_block *nb, *next_nb;

	nb = rcu_dereference_raw(*nl);

	while (nb && nr_to_call) {
		next_nb = rcu_dereference_raw(nb->next);

#ifdef CONFIG_DEBUG_NOTIFIERS
		if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
			WARN(1, "Invalid notifier called!");
			nb = next_nb;
			continue;
		}
#endif
		ret = nb->notifier_call(nb, val, v);

		if (nr_calls)
			(*nr_calls)++;

		if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
			break;
		nb = next_nb;
		nr_to_call--;
	}
	return ret;
}


int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
		struct notifier_block *n)
{
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&nh->lock, flags);
	ret = notifier_chain_register(&nh->head, n);
	spin_unlock_irqrestore(&nh->lock, flags);
	return ret;
}
EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);

int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
		struct notifier_block *n)
{
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&nh->lock, flags);
	ret = notifier_chain_unregister(&nh->head, n);
	spin_unlock_irqrestore(&nh->lock, flags);
	synchronize_rcu();
	return ret;
}
EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);

int __kprobes __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
					unsigned long val, void *v,
					int nr_to_call, int *nr_calls)
{
	int ret;

	rcu_read_lock();
	ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
	rcu_read_unlock();
	return ret;
}
EXPORT_SYMBOL_GPL(__atomic_notifier_call_chain);

int __kprobes atomic_notifier_call_chain(struct atomic_notifier_head *nh,
		unsigned long val, void *v)
{
	return __atomic_notifier_call_chain(nh, val, v, -1, NULL);
}
EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);


int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
		struct notifier_block *n)
{
	int ret;

	if (unlikely(system_state == SYSTEM_BOOTING))
		return notifier_chain_register(&nh->head, n);

	down_write(&nh->rwsem);
	ret = notifier_chain_register(&nh->head, n);
	up_write(&nh->rwsem);
	return ret;
}
EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);

int blocking_notifier_chain_cond_register(struct blocking_notifier_head *nh,
		struct notifier_block *n)
{
	int ret;

	down_write(&nh->rwsem);
	ret = notifier_chain_cond_register(&nh->head, n);
	up_write(&nh->rwsem);
	return ret;
}
EXPORT_SYMBOL_GPL(blocking_notifier_chain_cond_register);

int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
		struct notifier_block *n)
{
	int ret;

	if (unlikely(system_state == SYSTEM_BOOTING))
		return notifier_chain_unregister(&nh->head, n);

	down_write(&nh->rwsem);
	ret = notifier_chain_unregister(&nh->head, n);
	up_write(&nh->rwsem);
	return ret;
}
EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);

int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
				   unsigned long val, void *v,
				   int nr_to_call, int *nr_calls)
{
	int ret = NOTIFY_DONE;

	if (rcu_dereference_raw(nh->head)) {
		down_read(&nh->rwsem);
		ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
					nr_calls);
		up_read(&nh->rwsem);
	}
	return ret;
}
EXPORT_SYMBOL_GPL(__blocking_notifier_call_chain);

int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
		unsigned long val, void *v)
{
	return __blocking_notifier_call_chain(nh, val, v, -1, NULL);
}
EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);


int raw_notifier_chain_register(struct raw_notifier_head *nh,
		struct notifier_block *n)
{
	return notifier_chain_register(&nh->head, n);
}
EXPORT_SYMBOL_GPL(raw_notifier_chain_register);

int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
		struct notifier_block *n)
{
	return notifier_chain_unregister(&nh->head, n);
}
EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);

int __raw_notifier_call_chain(struct raw_notifier_head *nh,
			      unsigned long val, void *v,
			      int nr_to_call, int *nr_calls)
{
	return notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
}
EXPORT_SYMBOL_GPL(__raw_notifier_call_chain);

int raw_notifier_call_chain(struct raw_notifier_head *nh,
		unsigned long val, void *v)
{
	return __raw_notifier_call_chain(nh, val, v, -1, NULL);
}
EXPORT_SYMBOL_GPL(raw_notifier_call_chain);


int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
		struct notifier_block *n)
{
	int ret;

	if (unlikely(system_state == SYSTEM_BOOTING))
		return notifier_chain_register(&nh->head, n);

	mutex_lock(&nh->mutex);
	ret = notifier_chain_register(&nh->head, n);
	mutex_unlock(&nh->mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(srcu_notifier_chain_register);

int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
		struct notifier_block *n)
{
	int ret;

	if (unlikely(system_state == SYSTEM_BOOTING))
		return notifier_chain_unregister(&nh->head, n);

	mutex_lock(&nh->mutex);
	ret = notifier_chain_unregister(&nh->head, n);
	mutex_unlock(&nh->mutex);
	synchronize_srcu(&nh->srcu);
	return ret;
}
EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);

int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
			       unsigned long val, void *v,
			       int nr_to_call, int *nr_calls)
{
	int ret;
	int idx;

	idx = srcu_read_lock(&nh->srcu);
	ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
	srcu_read_unlock(&nh->srcu, idx);
	return ret;
}
EXPORT_SYMBOL_GPL(__srcu_notifier_call_chain);

int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
		unsigned long val, void *v)
{
	return __srcu_notifier_call_chain(nh, val, v, -1, NULL);
}
EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);

void srcu_init_notifier_head(struct srcu_notifier_head *nh)
{
	mutex_init(&nh->mutex);
	if (init_srcu_struct(&nh->srcu) < 0)
		BUG();
	nh->head = NULL;
}
EXPORT_SYMBOL_GPL(srcu_init_notifier_head);

static ATOMIC_NOTIFIER_HEAD(die_chain);

int notrace __kprobes notify_die(enum die_val val, const char *str,
	       struct pt_regs *regs, long err, int trap, int sig)
{
	struct die_args args = {
		.regs	= regs,
		.str	= str,
		.err	= err,
		.trapnr	= trap,
		.signr	= sig,

	};
	return atomic_notifier_call_chain(&die_chain, val, &args);
}

int register_die_notifier(struct notifier_block *nb)
{
	vmalloc_sync_all();
	return atomic_notifier_chain_register(&die_chain, nb);
}
EXPORT_SYMBOL_GPL(register_die_notifier);

int unregister_die_notifier(struct notifier_block *nb)
{
	return atomic_notifier_chain_unregister(&die_chain, nb);
}
EXPORT_SYMBOL_GPL(unregister_die_notifier);