From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/kernel/notifier.c | 186 +++++++++++++++++++++++-----------------------
1 files changed, 92 insertions(+), 94 deletions(-)
diff --git a/kernel/kernel/notifier.c b/kernel/kernel/notifier.c
index 59a1e9b..1b019cb 100644
--- a/kernel/kernel/notifier.c
+++ b/kernel/kernel/notifier.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kdebug.h>
#include <linux/kprobes.h>
#include <linux/export.h>
@@ -22,21 +23,10 @@
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)
+ if (unlikely((*nl) == n)) {
+ WARN(1, "double register detected");
return 0;
+ }
if (n->priority > (*nl)->priority)
break;
nl = &((*nl)->next);
@@ -104,6 +94,34 @@
}
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).
@@ -154,13 +172,30 @@
}
EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
+int atomic_notifier_call_chain_robust(struct atomic_notifier_head *nh,
+ unsigned long val_up, unsigned long val_down, void *v)
+{
+ unsigned long flags;
+ int ret;
+
+ /*
+ * Musn't use RCU; because then the notifier list can
+ * change between the up and down traversal.
+ */
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_call_chain_robust(&nh->head, val_up, val_down, v);
+ spin_unlock_irqrestore(&nh->lock, flags);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(atomic_notifier_call_chain_robust);
+NOKPROBE_SYMBOL(atomic_notifier_call_chain_robust);
+
/**
- * __atomic_notifier_call_chain - Call functions in an atomic notifier chain
+ * 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.
@@ -173,24 +208,16 @@
* 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 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, nr_to_call, nr_calls);
+ 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);
-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);
+ return ret;
}
EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
NOKPROBE_SYMBOL(atomic_notifier_call_chain);
@@ -231,29 +258,6 @@
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
@@ -283,13 +287,30 @@
}
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
+ * 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.
@@ -301,9 +322,8 @@
* 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 blocking_notifier_call_chain(struct blocking_notifier_head *nh,
+ unsigned long val, void *v)
{
int ret = NOTIFY_DONE;
@@ -314,18 +334,10 @@
*/
if (rcu_access_pointer(nh->head)) {
down_read(&nh->rwsem);
- ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
- nr_calls);
+ ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
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);
@@ -368,13 +380,18 @@
}
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
+ * 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.
@@ -387,18 +404,10 @@
* 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);
+ return notifier_call_chain(&nh->head, val, v, -1, NULL);
}
EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
@@ -470,12 +479,10 @@
EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);
/**
- * __srcu_notifier_call_chain - Call functions in an SRCU notifier chain
+ * 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.
@@ -487,24 +494,16 @@
* 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 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, nr_to_call, nr_calls);
+ 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);
-
-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);
@@ -552,7 +551,6 @@
int register_die_notifier(struct notifier_block *nb)
{
- vmalloc_sync_mappings();
return atomic_notifier_chain_register(&die_chain, nb);
}
EXPORT_SYMBOL_GPL(register_die_notifier);
--
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