587 lines
17 KiB
C
587 lines
17 KiB
C
#include <linux/kdebug.h>
|
|
#include <linux/kprobes.h>
|
|
#include <linux/module.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 __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(*nl);
|
|
|
|
while (nb && nr_to_call) {
|
|
next_nb = rcu_dereference(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;
|
|
}
|
|
|
|
/*
|
|
* 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 __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);
|
|
|
|
/*
|
|
* 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_dereference(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);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/**
|
|
* register_reboot_notifier - Register function to be called at reboot time
|
|
* @nb: Info about notifier function to be called
|
|
*
|
|
* Registers a function with the list of functions
|
|
* to be called at reboot time.
|
|
*
|
|
* Currently always returns zero, as blocking_notifier_chain_register()
|
|
* always returns zero.
|
|
*/
|
|
int register_reboot_notifier(struct notifier_block *nb)
|
|
{
|
|
return blocking_notifier_chain_register(&reboot_notifier_list, nb);
|
|
}
|
|
EXPORT_SYMBOL(register_reboot_notifier);
|
|
|
|
/**
|
|
* unregister_reboot_notifier - Unregister previously registered reboot notifier
|
|
* @nb: Hook to be unregistered
|
|
*
|
|
* Unregisters a previously registered reboot
|
|
* notifier function.
|
|
*
|
|
* Returns zero on success, or %-ENOENT on failure.
|
|
*/
|
|
int unregister_reboot_notifier(struct notifier_block *nb)
|
|
{
|
|
return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
|
|
}
|
|
EXPORT_SYMBOL(unregister_reboot_notifier);
|
|
|
|
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,
|
|
|
|
};
|
|
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);
|