#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>

/*

* Notifier list for kernel code which wants to be called

* at shutdown. This is used to stop any idling DMA operations

* and the like.

*/

BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);

/*

* Notifier chain core routines. The exported routines below

* are layered on top of these, with appropriate locking added.

*/

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;

}

/**

* notifier_call_chain - Informs the registered notifiers about an event.

* @nl: Pointer to head of the blocking notifier chain

* @val: Value passed unmodified to notifier function

* @v: Pointer passed unmodified to notifier function

* @nr_to_call: Number of notifier functions to be called. Don't care

* value of this parameter is -1.

* @nr_calls: Records the number of notifications sent. Don't care

* value of this field is NULL.

* @returns: notifier_call_chain returns the value returned by the

* last notifier function called.

*/

static int 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)

break;

nb = next_nb;

nr_to_call--;

}

return ret;

}

NOKPROBE_SYMBOL(notifier_call_chain);

/*

* Atomic notifier chain routines. Registration and unregistration

* use a spinlock, and call_chain is synchronized by RCU (no locks).

*/

/**

* atomic_notifier_chain_register - Add notifier to an atomic notifier chain

* @nh: Pointer to head of the atomic notifier chain

* @n: New entry in notifier chain

*

* Adds a notifier to an atomic notifier chain.

*

* Currently always returns zero.

*/

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);

/**

* atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain

* @nh: Pointer to head of the atomic notifier chain

* @n: Entry to remove from notifier chain

*

* Removes a notifier from an atomic notifier chain.

*

* Returns zero on success or %-ENOENT on failure.

*/

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);

/**

* __atomic_notifier_call_chain - Call functions in an atomic notifier chain

* @nh: Pointer to head of the atomic notifier chain

* @val: Value passed unmodified to notifier function

* @v: Pointer passed unmodified to notifier function

* @nr_to_call: See the comment for notifier_call_chain.

* @nr_calls: See the comment for notifier_call_chain.

*

* Calls each function in a notifier chain in turn. The functions

* run in an atomic context, so they must not block.

* This routine uses RCU to synchronize with changes to the chain.

*

* If the return value of the notifier can be and'ed

* with %NOTIFY_STOP_MASK then atomic_notifier_call_chain()

* will return immediately, with the return value of

* the notifier function which halted execution.

* Otherwise the return value is the return value

* of the last notifier function called.

*/

int __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);

NOKPROBE_SYMBOL(__atomic_notifier_call_chain);

int 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);

NOKPROBE_SYMBOL(atomic_notifier_call_chain);

/*

* Blocking notifier chain routines. All access to the chain is

* synchronized by an rwsem.

*/

/**

* blocking_notifier_chain_register - Add notifier to a blocking notifier chain

* @nh: Pointer to head of the blocking notifier chain

* @n: New entry in notifier chain

*

* Adds a notifier to a blocking notifier chain.

* Must be called in process context.

*

* Currently always returns zero.

*/

int blocking_notifier_chain_register(struct blocking_notifier_head *nh,

struct notifier_block *n)

{

int ret;

/*

* This code gets used during boot-up, when task switching is

* not yet working and interrupts must remain disabled. At

* such times we must not call down_write().

*/

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);

/**

* blocking_notifier_chain_cond_register - Cond add notifier to a blocking notifier chain

* @nh: Pointer to head of the blocking notifier chain

* @n: New entry in notifier chain

*

* Adds a notifier to a blocking notifier chain, only if not already

* present in the chain.

* Must be called in process context.

*

* Currently always returns zero.

*/

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);

/**

* blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain

* @nh: Pointer to head of the blocking notifier chain

* @n: Entry to remove from notifier chain

*

* Removes a notifier from a blocking notifier chain.

* Must be called from process context.

*

* Returns zero on success or %-ENOENT on failure.

*/

int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,

struct notifier_block *n)

{

int ret;

/*

* This code gets used during boot-up, when task switching is

* not yet working and interrupts must remain disabled. At

* such times we must not call down_write().

*/

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);

/**

* __blocking_notifier_call_chain - Call functions in a blocking notifier chain

* @nh: Pointer to head of the blocking notifier chain

* @val: Value passed unmodified to notifier function

* @v: Pointer passed unmodified to notifier function

* @nr_to_call: See comment for notifier_call_chain.

* @nr_calls: See comment for notifier_call_chain.

*

* Calls each function in a notifier chain in turn. The functions

* run in a process context, so they are allowed to block.

*

* If the return value of the notifier can be and'ed

* with %NOTIFY_STOP_MASK then blocking_notifier_call_chain()

* will return immediately, with the return value of

* the notifier function which halted execution.

* Otherwise the return value is the return value

* of the last notifier function called.

*/

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;

/*

* We check the head outside the lock, but if this access is

* racy then it does not matter what the result of the test

* is, we re-check the list after having taken the lock anyway:

*/

if (rcu_access_pointer(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);

/*

* Raw notifier chain routines. There is no protection;

* the caller must provide it. Use at your own risk!

*/

/**

* raw_notifier_chain_register - Add notifier to a raw notifier chain

* @nh: Pointer to head of the raw notifier chain

* @n: New entry in notifier chain

*

* Adds a notifier to a raw notifier chain.

* All locking must be provided by the caller.

*

* Currently always returns zero.

*/

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);

/**

* raw_notifier_chain_unregister - Remove notifier from a raw notifier chain

* @nh: Pointer to head of the raw notifier chain

* @n: Entry to remove from notifier chain

*

* Removes a notifier from a raw notifier chain.

* All locking must be provided by the caller.

*

* Returns zero on success or %-ENOENT on failure.

*/

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);

/**

* __raw_notifier_call_chain - Call functions in a raw notifier chain

* @nh: Pointer to head of the raw notifier chain

* @val: Value passed unmodified to notifier function

* @v: Pointer passed unmodified to notifier function

* @nr_to_call: See comment for notifier_call_chain.

* @nr_calls: See comment for notifier_call_chain

*

* Calls each function in a notifier chain in turn. The functions

* run in an undefined context.

* All locking must be provided by the caller.

*

* If the return value of the notifier can be and'ed

* with %NOTIFY_STOP_MASK then raw_notifier_call_chain()

* will return immediately, with the return value of

* the notifier function which halted execution.

* Otherwise the return value is the return value

* of the last notifier function called.

*/

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);

#ifdef CONFIG_SRCU

/*

* SRCU notifier chain routines. Registration and unregistration

* use a mutex, and call_chain is synchronized by SRCU (no locks).

*/

/**

* srcu_notifier_chain_register - Add notifier to an SRCU notifier chain

* @nh: Pointer to head of the SRCU notifier chain

* @n: New entry in notifier chain

*

* Adds a notifier to an SRCU notifier chain.

* Must be called in process context.

*

* Currently always returns zero.

*/

int srcu_notifier_chain_register(struct srcu_notifier_head *nh,

struct notifier_block *n)

{

int ret;

/*

* This code gets used during boot-up, when task switching is

* not yet working and interrupts must remain disabled. At

* such times we must not call mutex_lock().

*/

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);

/**

* srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain

* @nh: Pointer to head of the SRCU notifier chain

* @n: Entry to remove from notifier chain

*

* Removes a notifier from an SRCU notifier chain.

* Must be called from process context.

*

* Returns zero on success or %-ENOENT on failure.

*/

int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,

struct notifier_block *n)

{

int ret;

/*

* This code gets used during boot-up, when task switching is

* not yet working and interrupts must remain disabled. At

* such times we must not call mutex_lock().

*/

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);

/**

* __srcu_notifier_call_chain - Call functions in an SRCU notifier chain

* @nh: Pointer to head of the SRCU notifier chain

* @val: Value passed unmodified to notifier function

* @v: Pointer passed unmodified to notifier function

* @nr_to_call: See comment for notifier_call_chain.

* @nr_calls: See comment for notifier_call_chain

*

* Calls each function in a notifier chain in turn. The functions

* run in a process context, so they are allowed to block.

*

* If the return value of the notifier can be and'ed

* with %NOTIFY_STOP_MASK then srcu_notifier_call_chain()

* will return immediately, with the return value of

* the notifier function which halted execution.

* Otherwise the return value is the return value

* of the last notifier function called.

*/

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);

/**

* srcu_init_notifier_head - Initialize an SRCU notifier head

* @nh: Pointer to head of the srcu notifier chain

*

* Unlike other sorts of notifier heads, SRCU notifier heads require

* dynamic initialization. Be sure to call this routine before

* calling any of the other SRCU notifier routines for this head.

*

* If an SRCU notifier head is deallocated, it must first be cleaned

* up by calling srcu_cleanup_notifier_head(). Otherwise the head's

* per-cpu data (used by the SRCU mechanism) will leak.

*/

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);

#endif /* CONFIG_SRCU */

static ATOMIC_NOTIFIER_HEAD(die_chain);

int notrace 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,

};

RCU_LOCKDEP_WARN(!rcu_is_watching(),

"notify_die called but RCU thinks we're quiescent");

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

}

NOKPROBE_SYMBOL(notify_die);

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);