Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 607 insertions, 0 deletions

diff --git a/kernel/notifier.c b/kernel/notifier.c
new file mode 100644
index 000000000..0d5bd62c4
--- /dev/null
+++ b/kernel/notifier.c
@@ -0,0 +1,607 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#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,
+				   bool unique_priority)
+{
+	while ((*nl) != NULL) {
+		if (unlikely((*nl) == n)) {
+			WARN(1, "notifier callback %ps already registered",
+			     n->notifier_call);
+			return -EEXIST;
+		}
+		if (n->priority > (*nl)->priority)
+			break;
+		if (n->priority == (*nl)->priority && unique_priority)
+			return -EBUSY;
+		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);
+
+/**
+ * notifier_call_chain_robust - Inform the registered notifiers about an event
+ *                              and rollback on error.
+ * @nl:		Pointer to head of the blocking notifier chain
+ * @val_up:	Value passed unmodified to the notifier function
+ * @val_down:	Value passed unmodified to the notifier function when recovering
+ *              from an error on @val_up
+ * @v		Pointer passed unmodified to the notifier function
+ *
+ * NOTE:	It is important the @nl chain doesn't change between the two
+ *		invocations of notifier_call_chain() such that we visit the
+ *		exact same notifier callbacks; this rules out any RCU usage.
+ *
+ * Returns:	the return value of the @val_up call.
+ */
+static int notifier_call_chain_robust(struct notifier_block **nl,
+				     unsigned long val_up, unsigned long val_down,
+				     void *v)
+{
+	int ret, nr = 0;
+
+	ret = notifier_call_chain(nl, val_up, v, -1, &nr);
+	if (ret & NOTIFY_STOP_MASK)
+		notifier_call_chain(nl, val_down, v, nr-1, NULL);
+
+	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.
+ *
+ *	Returns 0 on success, %-EEXIST on error.
+ */
+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, false);
+	spin_unlock_irqrestore(&nh->lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
+
+/**
+ *	atomic_notifier_chain_register_unique_prio - 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 if there is no other
+ *	notifier registered using the same priority.
+ *
+ *	Returns 0 on success, %-EEXIST or %-EBUSY on error.
+ */
+int atomic_notifier_chain_register_unique_prio(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, true);
+	spin_unlock_irqrestore(&nh->lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_register_unique_prio);
+
+/**
+ *	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
+ *
+ *	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 ret;
+
+	rcu_read_lock();
+	ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
+	rcu_read_unlock();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
+NOKPROBE_SYMBOL(atomic_notifier_call_chain);
+
+/**
+ *	atomic_notifier_call_chain_is_empty - Check whether notifier chain is empty
+ *	@nh: Pointer to head of the atomic notifier chain
+ *
+ *	Checks whether notifier chain is empty.
+ *
+ *	Returns true is notifier chain is empty, false otherwise.
+ */
+bool atomic_notifier_call_chain_is_empty(struct atomic_notifier_head *nh)
+{
+	return !rcu_access_pointer(nh->head);
+}
+
+/*
+ *	Blocking notifier chain routines.  All access to the chain is
+ *	synchronized by an rwsem.
+ */
+
+static int __blocking_notifier_chain_register(struct blocking_notifier_head *nh,
+					      struct notifier_block *n,
+					      bool unique_priority)
+{
+	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, unique_priority);
+
+	down_write(&nh->rwsem);
+	ret = notifier_chain_register(&nh->head, n, unique_priority);
+	up_write(&nh->rwsem);
+	return ret;
+}
+
+/**
+ *	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.
+ *
+ *	Returns 0 on success, %-EEXIST on error.
+ */
+int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
+		struct notifier_block *n)
+{
+	return __blocking_notifier_chain_register(nh, n, false);
+}
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
+
+/**
+ *	blocking_notifier_chain_register_unique_prio - 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 an blocking notifier chain if there is no other
+ *	notifier registered using the same priority.
+ *
+ *	Returns 0 on success, %-EEXIST or %-EBUSY on error.
+ */
+int blocking_notifier_chain_register_unique_prio(struct blocking_notifier_head *nh,
+						 struct notifier_block *n)
+{
+	return __blocking_notifier_chain_register(nh, n, true);
+}
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_register_unique_prio);
+
+/**
+ *	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);
+
+int blocking_notifier_call_chain_robust(struct blocking_notifier_head *nh,
+		unsigned long val_up, unsigned long val_down, void *v)
+{
+	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_robust(&nh->head, val_up, val_down, v);
+		up_read(&nh->rwsem);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(blocking_notifier_call_chain_robust);
+
+/**
+ *	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
+ *
+ *	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 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, -1, NULL);
+		up_read(&nh->rwsem);
+	}
+	return ret;
+}
+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.
+ *
+ *	Returns 0 on success, %-EEXIST on error.
+ */
+int raw_notifier_chain_register(struct raw_notifier_head *nh,
+		struct notifier_block *n)
+{
+	return notifier_chain_register(&nh->head, n, false);
+}
+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);
+
+int raw_notifier_call_chain_robust(struct raw_notifier_head *nh,
+		unsigned long val_up, unsigned long val_down, void *v)
+{
+	return notifier_call_chain_robust(&nh->head, val_up, val_down, v);
+}
+EXPORT_SYMBOL_GPL(raw_notifier_call_chain_robust);
+
+/**
+ *	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
+ *
+ *	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)
+{
+	return notifier_call_chain(&nh->head, 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.
+ *
+ *	Returns 0 on success, %-EEXIST on error.
+ */
+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, false);
+
+	mutex_lock(&nh->mutex);
+	ret = notifier_chain_register(&nh->head, n, false);
+	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
+ *
+ *	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 ret;
+	int idx;
+
+	idx = srcu_read_lock(&nh->srcu);
+	ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
+	srcu_read_unlock(&nh->srcu, idx);
+	return ret;
+}
+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)
+{
+	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);