1 files changed, 663 insertions, 160 deletions

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 60f48fa0fd0d..7cb19e601426 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -1,8 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * jump label support
  *
  * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
- * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com>
+ * Copyright (C) 2011 Peter Zijlstra
  *
  */
 #include <linux/memory.h>
@@ -13,10 +14,12 @@
 #include <linux/sort.h>
 #include <linux/err.h>
 #include <linux/static_key.h>
+#include <linux/jump_label_ratelimit.h>
+#include <linux/bug.h>
+#include <linux/cpu.h>
+#include <asm/sections.h>
 
-#ifdef HAVE_JUMP_LABEL
-
-/* mutex to protect coming/going of the the jump_label table */
+/* mutex to protect coming/going of the jump_label table */
 static DEFINE_MUTEX(jump_label_mutex);
 
 void jump_label_lock(void)
@@ -34,87 +37,336 @@ static int jump_label_cmp(const void *a, const void *b)
 	const struct jump_entry *jea = a;
 	const struct jump_entry *jeb = b;
 
-	if (jea->key < jeb->key)
+	/*
+	 * Entrires are sorted by key.
+	 */
+	if (jump_entry_key(jea) < jump_entry_key(jeb))
+		return -1;
+
+	if (jump_entry_key(jea) > jump_entry_key(jeb))
+		return 1;
+
+	/*
+	 * In the batching mode, entries should also be sorted by the code
+	 * inside the already sorted list of entries, enabling a bsearch in
+	 * the vector.
+	 */
+	if (jump_entry_code(jea) < jump_entry_code(jeb))
 		return -1;
 
-	if (jea->key > jeb->key)
+	if (jump_entry_code(jea) > jump_entry_code(jeb))
 		return 1;
 
 	return 0;
 }
 
+static void jump_label_swap(void *a, void *b, int size)
+{
+	long delta = (unsigned long)a - (unsigned long)b;
+	struct jump_entry *jea = a;
+	struct jump_entry *jeb = b;
+	struct jump_entry tmp = *jea;
+
+	jea->code	= jeb->code - delta;
+	jea->target	= jeb->target - delta;
+	jea->key	= jeb->key - delta;
+
+	jeb->code	= tmp.code + delta;
+	jeb->target	= tmp.target + delta;
+	jeb->key	= tmp.key + delta;
+}
+
 static void
 jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
 {
 	unsigned long size;
+	void *swapfn = NULL;
+
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE))
+		swapfn = jump_label_swap;
 
 	size = (((unsigned long)stop - (unsigned long)start)
 					/ sizeof(struct jump_entry));
-	sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
+	sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn);
+}
+
+static void jump_label_update(struct static_key *key);
+
+/*
+ * There are similar definitions for the !CONFIG_JUMP_LABEL case in jump_label.h.
+ * The use of 'atomic_read()' requires atomic.h and its problematic for some
+ * kernel headers such as kernel.h and others. Since static_key_count() is not
+ * used in the branch statements as it is for the !CONFIG_JUMP_LABEL case its ok
+ * to have it be a function here. Similarly, for 'static_key_enable()' and
+ * 'static_key_disable()', which require bug.h. This should allow jump_label.h
+ * to be included from most/all places for CONFIG_JUMP_LABEL.
+ */
+int static_key_count(struct static_key *key)
+{
+	/*
+	 * -1 means the first static_key_slow_inc() is in progress.
+	 *  static_key_enabled() must return true, so return 1 here.
+	 */
+	int n = atomic_read(&key->enabled);
+
+	return n >= 0 ? n : 1;
 }
+EXPORT_SYMBOL_GPL(static_key_count);
 
-static void jump_label_update(struct static_key *key, int enable);
+/*
+ * static_key_fast_inc_not_disabled - adds a user for a static key
+ * @key: static key that must be already enabled
+ *
+ * The caller must make sure that the static key can't get disabled while
+ * in this function. It doesn't patch jump labels, only adds a user to
+ * an already enabled static key.
+ *
+ * Returns true if the increment was done. Unlike refcount_t the ref counter
+ * is not saturated, but will fail to increment on overflow.
+ */
+bool static_key_fast_inc_not_disabled(struct static_key *key)
+{
+	int v;
+
+	STATIC_KEY_CHECK_USE(key);
+	/*
+	 * Negative key->enabled has a special meaning: it sends
+	 * static_key_slow_inc/dec() down the slow path, and it is non-zero
+	 * so it counts as "enabled" in jump_label_update().
+	 *
+	 * The INT_MAX overflow condition is either used by the networking
+	 * code to reset or detected in the slow path of
+	 * static_key_slow_inc_cpuslocked().
+	 */
+	v = atomic_read(&key->enabled);
+	do {
+		if (v <= 0 || v == INT_MAX)
+			return false;
+	} while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1)));
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(static_key_fast_inc_not_disabled);
+
+bool static_key_slow_inc_cpuslocked(struct static_key *key)
+{
+	lockdep_assert_cpus_held();
+
+	/*
+	 * Careful if we get concurrent static_key_slow_inc/dec() calls;
+	 * later calls must wait for the first one to _finish_ the
+	 * jump_label_update() process.  At the same time, however,
+	 * the jump_label_update() call below wants to see
+	 * static_key_enabled(&key) for jumps to be updated properly.
+	 */
+	if (static_key_fast_inc_not_disabled(key))
+		return true;
+
+	guard(mutex)(&jump_label_mutex);
+	/* Try to mark it as 'enabling in progress. */
+	if (!atomic_cmpxchg(&key->enabled, 0, -1)) {
+		jump_label_update(key);
+		/*
+		 * Ensure that when static_key_fast_inc_not_disabled() or
+		 * static_key_dec_not_one() observe the positive value,
+		 * they must also observe all the text changes.
+		 */
+		atomic_set_release(&key->enabled, 1);
+	} else {
+		/*
+		 * While holding the mutex this should never observe
+		 * anything else than a value >= 1 and succeed
+		 */
+		if (WARN_ON_ONCE(!static_key_fast_inc_not_disabled(key)))
+			return false;
+	}
+	return true;
+}
 
-void static_key_slow_inc(struct static_key *key)
+bool static_key_slow_inc(struct static_key *key)
 {
-	if (atomic_inc_not_zero(&key->enabled))
+	bool ret;
+
+	cpus_read_lock();
+	ret = static_key_slow_inc_cpuslocked(key);
+	cpus_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(static_key_slow_inc);
+
+void static_key_enable_cpuslocked(struct static_key *key)
+{
+	STATIC_KEY_CHECK_USE(key);
+	lockdep_assert_cpus_held();
+
+	if (atomic_read(&key->enabled) > 0) {
+		WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
 		return;
+	}
 
 	jump_label_lock();
 	if (atomic_read(&key->enabled) == 0) {
-		if (!jump_label_get_branch_default(key))
-			jump_label_update(key, JUMP_LABEL_ENABLE);
-		else
-			jump_label_update(key, JUMP_LABEL_DISABLE);
+		atomic_set(&key->enabled, -1);
+		jump_label_update(key);
+		/*
+		 * See static_key_slow_inc().
+		 */
+		atomic_set_release(&key->enabled, 1);
 	}
-	atomic_inc(&key->enabled);
 	jump_label_unlock();
 }
-EXPORT_SYMBOL_GPL(static_key_slow_inc);
+EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
+
+void static_key_enable(struct static_key *key)
+{
+	cpus_read_lock();
+	static_key_enable_cpuslocked(key);
+	cpus_read_unlock();
+}
+EXPORT_SYMBOL_GPL(static_key_enable);
 
-static void __static_key_slow_dec(struct static_key *key,
-		unsigned long rate_limit, struct delayed_work *work)
+void static_key_disable_cpuslocked(struct static_key *key)
 {
-	if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
-		WARN(atomic_read(&key->enabled) < 0,
-		     "jump label: negative count!\n");
+	STATIC_KEY_CHECK_USE(key);
+	lockdep_assert_cpus_held();
+
+	if (atomic_read(&key->enabled) != 1) {
+		WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
 		return;
 	}
 
-	if (rate_limit) {
-		atomic_inc(&key->enabled);
-		schedule_delayed_work(work, rate_limit);
-	} else {
-		if (!jump_label_get_branch_default(key))
-			jump_label_update(key, JUMP_LABEL_DISABLE);
-		else
-			jump_label_update(key, JUMP_LABEL_ENABLE);
-	}
+	jump_label_lock();
+	if (atomic_cmpxchg(&key->enabled, 1, 0) == 1)
+		jump_label_update(key);
 	jump_label_unlock();
 }
+EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
+
+void static_key_disable(struct static_key *key)
+{
+	cpus_read_lock();
+	static_key_disable_cpuslocked(key);
+	cpus_read_unlock();
+}
+EXPORT_SYMBOL_GPL(static_key_disable);
+
+static bool static_key_dec_not_one(struct static_key *key)
+{
+	int v;
+
+	/*
+	 * Go into the slow path if key::enabled is less than or equal than
+	 * one. One is valid to shut down the key, anything less than one
+	 * is an imbalance, which is handled at the call site.
+	 *
+	 * That includes the special case of '-1' which is set in
+	 * static_key_slow_inc_cpuslocked(), but that's harmless as it is
+	 * fully serialized in the slow path below. By the time this task
+	 * acquires the jump label lock the value is back to one and the
+	 * retry under the lock must succeed.
+	 */
+	v = atomic_read(&key->enabled);
+	do {
+		/*
+		 * Warn about the '-1' case though; since that means a
+		 * decrement is concurrent with a first (0->1) increment. IOW
+		 * people are trying to disable something that wasn't yet fully
+		 * enabled. This suggests an ordering problem on the user side.
+		 */
+		WARN_ON_ONCE(v < 0);
+
+		/*
+		 * Warn about underflow, and lie about success in an attempt to
+		 * not make things worse.
+		 */
+		if (WARN_ON_ONCE(v == 0))
+			return true;
+
+		if (v <= 1)
+			return false;
+	} while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v - 1)));
+
+	return true;
+}
+
+static void __static_key_slow_dec_cpuslocked(struct static_key *key)
+{
+	lockdep_assert_cpus_held();
+	int val;
+
+	if (static_key_dec_not_one(key))
+		return;
+
+	guard(mutex)(&jump_label_mutex);
+	val = atomic_read(&key->enabled);
+	/*
+	 * It should be impossible to observe -1 with jump_label_mutex held,
+	 * see static_key_slow_inc_cpuslocked().
+	 */
+	if (WARN_ON_ONCE(val == -1))
+		return;
+	/*
+	 * Cannot already be 0, something went sideways.
+	 */
+	if (WARN_ON_ONCE(val == 0))
+		return;
+
+	if (atomic_dec_and_test(&key->enabled))
+		jump_label_update(key);
+}
+
+static void __static_key_slow_dec(struct static_key *key)
+{
+	cpus_read_lock();
+	__static_key_slow_dec_cpuslocked(key);
+	cpus_read_unlock();
+}
 
-static void jump_label_update_timeout(struct work_struct *work)
+void jump_label_update_timeout(struct work_struct *work)
 {
 	struct static_key_deferred *key =
 		container_of(work, struct static_key_deferred, work.work);
-	__static_key_slow_dec(&key->key, 0, NULL);
+	__static_key_slow_dec(&key->key);
 }
+EXPORT_SYMBOL_GPL(jump_label_update_timeout);
 
 void static_key_slow_dec(struct static_key *key)
 {
-	__static_key_slow_dec(key, 0, NULL);
+	STATIC_KEY_CHECK_USE(key);
+	__static_key_slow_dec(key);
 }
 EXPORT_SYMBOL_GPL(static_key_slow_dec);
 
-void static_key_slow_dec_deferred(struct static_key_deferred *key)
+void static_key_slow_dec_cpuslocked(struct static_key *key)
+{
+	STATIC_KEY_CHECK_USE(key);
+	__static_key_slow_dec_cpuslocked(key);
+}
+
+void __static_key_slow_dec_deferred(struct static_key *key,
+				    struct delayed_work *work,
+				    unsigned long timeout)
 {
-	__static_key_slow_dec(&key->key, key->timeout, &key->work);
+	STATIC_KEY_CHECK_USE(key);
+
+	if (static_key_dec_not_one(key))
+		return;
+
+	schedule_delayed_work(work, timeout);
+}
+EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
+
+void __static_key_deferred_flush(void *key, struct delayed_work *work)
+{
+	STATIC_KEY_CHECK_USE(key);
+	flush_delayed_work(work);
 }
-EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
+EXPORT_SYMBOL_GPL(__static_key_deferred_flush);
 
 void jump_label_rate_limit(struct static_key_deferred *key,
 		unsigned long rl)
 {
+	STATIC_KEY_CHECK_USE(key);
 	key->timeout = rl;
 	INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
 }
@@ -122,67 +374,153 @@ EXPORT_SYMBOL_GPL(jump_label_rate_limit);
 
 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
 {
-	if (entry->code <= (unsigned long)end &&
-		entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
+	if (jump_entry_code(entry) <= (unsigned long)end &&
+	    jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start)
 		return 1;
 
 	return 0;
 }
 
 static int __jump_label_text_reserved(struct jump_entry *iter_start,
-		struct jump_entry *iter_stop, void *start, void *end)
+		struct jump_entry *iter_stop, void *start, void *end, bool init)
 {
 	struct jump_entry *iter;
 
 	iter = iter_start;
 	while (iter < iter_stop) {
-		if (addr_conflict(iter, start, end))
-			return 1;
+		if (init || !jump_entry_is_init(iter)) {
+			if (addr_conflict(iter, start, end))
+				return 1;
+		}
 		iter++;
 	}
 
 	return 0;
 }
 
-/* 
- * Update code which is definitely not currently executing.
- * Architectures which need heavyweight synchronization to modify
- * running code can override this to make the non-live update case
- * cheaper.
+#ifndef arch_jump_label_transform_static
+static void arch_jump_label_transform_static(struct jump_entry *entry,
+					     enum jump_label_type type)
+{
+	/* nothing to do on most architectures */
+}
+#endif
+
+static inline struct jump_entry *static_key_entries(struct static_key *key)
+{
+	WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
+	return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
+}
+
+static inline bool static_key_type(struct static_key *key)
+{
+	return key->type & JUMP_TYPE_TRUE;
+}
+
+static inline bool static_key_linked(struct static_key *key)
+{
+	return key->type & JUMP_TYPE_LINKED;
+}
+
+static inline void static_key_clear_linked(struct static_key *key)
+{
+	key->type &= ~JUMP_TYPE_LINKED;
+}
+
+static inline void static_key_set_linked(struct static_key *key)
+{
+	key->type |= JUMP_TYPE_LINKED;
+}
+
+/***
+ * A 'struct static_key' uses a union such that it either points directly
+ * to a table of 'struct jump_entry' or to a linked list of modules which in
+ * turn point to 'struct jump_entry' tables.
+ *
+ * The two lower bits of the pointer are used to keep track of which pointer
+ * type is in use and to store the initial branch direction, we use an access
+ * function which preserves these bits.
  */
-void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
-					    enum jump_label_type type)
+static void static_key_set_entries(struct static_key *key,
+				   struct jump_entry *entries)
 {
-	arch_jump_label_transform(entry, type);	
+	unsigned long type;
+
+	WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
+	type = key->type & JUMP_TYPE_MASK;
+	key->entries = entries;
+	key->type |= type;
 }
 
-static void __jump_label_update(struct static_key *key,
-				struct jump_entry *entry,
-				struct jump_entry *stop, int enable)
+static enum jump_label_type jump_label_type(struct jump_entry *entry)
 {
-	for (; (entry < stop) &&
-	      (entry->key == (jump_label_t)(unsigned long)key);
-	      entry++) {
+	struct static_key *key = jump_entry_key(entry);
+	bool enabled = static_key_enabled(key);
+	bool branch = jump_entry_is_branch(entry);
+
+	/* See the comment in linux/jump_label.h */
+	return enabled ^ branch;
+}
+
+static bool jump_label_can_update(struct jump_entry *entry, bool init)
+{
+	/*
+	 * Cannot update code that was in an init text area.
+	 */
+	if (!init && jump_entry_is_init(entry))
+		return false;
+
+	if (!kernel_text_address(jump_entry_code(entry))) {
 		/*
-		 * entry->code set to 0 invalidates module init text sections
-		 * kernel_text_address() verifies we are not in core kernel
-		 * init code, see jump_label_invalidate_module_init().
+		 * This skips patching built-in __exit, which
+		 * is part of init_section_contains() but is
+		 * not part of kernel_text_address().
+		 *
+		 * Skipping built-in __exit is fine since it
+		 * will never be executed.
 		 */
-		if (entry->code && kernel_text_address(entry->code))
-			arch_jump_label_transform(entry, enable);
+		WARN_ONCE(!jump_entry_is_init(entry),
+			  "can't patch jump_label at %pS",
+			  (void *)jump_entry_code(entry));
+		return false;
 	}
+
+	return true;
 }
 
-static enum jump_label_type jump_label_type(struct static_key *key)
+#ifndef HAVE_JUMP_LABEL_BATCH
+static void __jump_label_update(struct static_key *key,
+				struct jump_entry *entry,
+				struct jump_entry *stop,
+				bool init)
 {
-	bool true_branch = jump_label_get_branch_default(key);
-	bool state = static_key_enabled(key);
+	for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
+		if (jump_label_can_update(entry, init))
+			arch_jump_label_transform(entry, jump_label_type(entry));
+	}
+}
+#else
+static void __jump_label_update(struct static_key *key,
+				struct jump_entry *entry,
+				struct jump_entry *stop,
+				bool init)
+{
+	for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
 
-	if ((!true_branch && state) || (true_branch && !state))
-		return JUMP_LABEL_ENABLE;
+		if (!jump_label_can_update(entry, init))
+			continue;
 
-	return JUMP_LABEL_DISABLE;
+		if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) {
+			/*
+			 * Queue is full: Apply the current queue and try again.
+			 */
+			arch_jump_label_transform_apply();
+			BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry)));
+		}
+	}
+	arch_jump_label_transform_apply();
 }
+#endif
 
 void __init jump_label_init(void)
 {
@@ -191,86 +529,170 @@ void __init jump_label_init(void)
 	struct static_key *key = NULL;
 	struct jump_entry *iter;
 
+	/*
+	 * Since we are initializing the static_key.enabled field with
+	 * with the 'raw' int values (to avoid pulling in atomic.h) in
+	 * jump_label.h, let's make sure that is safe. There are only two
+	 * cases to check since we initialize to 0 or 1.
+	 */
+	BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
+	BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
+
+	if (static_key_initialized)
+		return;
+
+	cpus_read_lock();
 	jump_label_lock();
 	jump_label_sort_entries(iter_start, iter_stop);
 
 	for (iter = iter_start; iter < iter_stop; iter++) {
 		struct static_key *iterk;
+		bool in_init;
+
+		/* rewrite NOPs */
+		if (jump_label_type(iter) == JUMP_LABEL_NOP)
+			arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
+
+		in_init = init_section_contains((void *)jump_entry_code(iter), 1);
+		jump_entry_set_init(iter, in_init);
 
-		iterk = (struct static_key *)(unsigned long)iter->key;
-		arch_jump_label_transform_static(iter, jump_label_type(iterk));
+		iterk = jump_entry_key(iter);
 		if (iterk == key)
 			continue;
 
 		key = iterk;
-		/*
-		 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
-		 */
-		*((unsigned long *)&key->entries) += (unsigned long)iter;
-#ifdef CONFIG_MODULES
-		key->next = NULL;
-#endif
+		static_key_set_entries(key, iter);
 	}
+	static_key_initialized = true;
 	jump_label_unlock();
+	cpus_read_unlock();
+}
+
+static inline bool static_key_sealed(struct static_key *key)
+{
+	return (key->type & JUMP_TYPE_LINKED) && !(key->type & ~JUMP_TYPE_MASK);
+}
+
+static inline void static_key_seal(struct static_key *key)
+{
+	unsigned long type = key->type & JUMP_TYPE_TRUE;
+	key->type = JUMP_TYPE_LINKED | type;
+}
+
+void jump_label_init_ro(void)
+{
+	struct jump_entry *iter_start = __start___jump_table;
+	struct jump_entry *iter_stop = __stop___jump_table;
+	struct jump_entry *iter;
+
+	if (WARN_ON_ONCE(!static_key_initialized))
+		return;
+
+	cpus_read_lock();
+	jump_label_lock();
+
+	for (iter = iter_start; iter < iter_stop; iter++) {
+		struct static_key *iterk = jump_entry_key(iter);
+
+		if (!is_kernel_ro_after_init((unsigned long)iterk))
+			continue;
+
+		if (static_key_sealed(iterk))
+			continue;
+
+		static_key_seal(iterk);
+	}
+
+	jump_label_unlock();
+	cpus_read_unlock();
 }
 
 #ifdef CONFIG_MODULES
 
+enum jump_label_type jump_label_init_type(struct jump_entry *entry)
+{
+	struct static_key *key = jump_entry_key(entry);
+	bool type = static_key_type(key);
+	bool branch = jump_entry_is_branch(entry);
+
+	/* See the comment in linux/jump_label.h */
+	return type ^ branch;
+}
+
 struct static_key_mod {
 	struct static_key_mod *next;
 	struct jump_entry *entries;
 	struct module *mod;
 };
 
+static inline struct static_key_mod *static_key_mod(struct static_key *key)
+{
+	WARN_ON_ONCE(!static_key_linked(key));
+	return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
+}
+
+/***
+ * key->type and key->next are the same via union.
+ * This sets key->next and preserves the type bits.
+ *
+ * See additional comments above static_key_set_entries().
+ */
+static void static_key_set_mod(struct static_key *key,
+			       struct static_key_mod *mod)
+{
+	unsigned long type;
+
+	WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
+	type = key->type & JUMP_TYPE_MASK;
+	key->next = mod;
+	key->type |= type;
+}
+
 static int __jump_label_mod_text_reserved(void *start, void *end)
 {
 	struct module *mod;
+	int ret;
 
-	mod = __module_text_address((unsigned long)start);
+	scoped_guard(rcu) {
+		mod = __module_text_address((unsigned long)start);
+		WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
+		if (!try_module_get(mod))
+			mod = NULL;
+	}
 	if (!mod)
 		return 0;
 
-	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
-
-	return __jump_label_text_reserved(mod->jump_entries,
+	ret = __jump_label_text_reserved(mod->jump_entries,
 				mod->jump_entries + mod->num_jump_entries,
-				start, end);
-}
+				start, end, mod->state == MODULE_STATE_COMING);
 
-static void __jump_label_mod_update(struct static_key *key, int enable)
-{
-	struct static_key_mod *mod = key->next;
+	module_put(mod);
 
-	while (mod) {
-		struct module *m = mod->mod;
-
-		__jump_label_update(key, mod->entries,
-				    m->jump_entries + m->num_jump_entries,
-				    enable);
-		mod = mod->next;
-	}
+	return ret;
 }
 
-/***
- * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
- * @mod: module to patch
- *
- * Allow for run-time selection of the optimal nops. Before the module
- * loads patch these with arch_get_jump_label_nop(), which is specified by
- * the arch specific jump label code.
- */
-void jump_label_apply_nops(struct module *mod)
+static void __jump_label_mod_update(struct static_key *key)
 {
-	struct jump_entry *iter_start = mod->jump_entries;
-	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
-	struct jump_entry *iter;
+	struct static_key_mod *mod;
 
-	/* if the module doesn't have jump label entries, just return */
-	if (iter_start == iter_stop)
-		return;
+	for (mod = static_key_mod(key); mod; mod = mod->next) {
+		struct jump_entry *stop;
+		struct module *m;
 
-	for (iter = iter_start; iter < iter_stop; iter++) {
-		arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
+		/*
+		 * NULL if the static_key is defined in a module
+		 * that does not use it
+		 */
+		if (!mod->entries)
+			continue;
+
+		m = mod->mod;
+		if (!m)
+			stop = __stop___jump_table;
+		else
+			stop = m->jump_entries + m->num_jump_entries;
+		__jump_label_update(key, mod->entries, stop,
+				    m && m->state == MODULE_STATE_COMING);
 	}
 }
 
@@ -280,7 +702,7 @@ static int jump_label_add_module(struct module *mod)
 	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 	struct jump_entry *iter;
 	struct static_key *key = NULL;
-	struct static_key_mod *jlm;
+	struct static_key_mod *jlm, *jlm2;
 
 	/* if the module doesn't have jump label entries, just return */
 	if (iter_start == iter_stop)
@@ -290,30 +712,57 @@ static int jump_label_add_module(struct module *mod)
 
 	for (iter = iter_start; iter < iter_stop; iter++) {
 		struct static_key *iterk;
+		bool in_init;
+
+		in_init = within_module_init(jump_entry_code(iter), mod);
+		jump_entry_set_init(iter, in_init);
 
-		iterk = (struct static_key *)(unsigned long)iter->key;
+		iterk = jump_entry_key(iter);
 		if (iterk == key)
 			continue;
 
 		key = iterk;
-		if (__module_address(iter->key) == mod) {
-			/*
-			 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
-			 */
-			*((unsigned long *)&key->entries) += (unsigned long)iter;
-			key->next = NULL;
+		if (within_module((unsigned long)key, mod)) {
+			static_key_set_entries(key, iter);
 			continue;
 		}
+
+		/*
+		 * If the key was sealed at init, then there's no need to keep a
+		 * reference to its module entries - just patch them now and be
+		 * done with it.
+		 */
+		if (static_key_sealed(key))
+			goto do_poke;
+
 		jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
 		if (!jlm)
 			return -ENOMEM;
+		if (!static_key_linked(key)) {
+			jlm2 = kzalloc(sizeof(struct static_key_mod),
+				       GFP_KERNEL);
+			if (!jlm2) {
+				kfree(jlm);
+				return -ENOMEM;
+			}
+			scoped_guard(rcu)
+				jlm2->mod = __module_address((unsigned long)key);
+
+			jlm2->entries = static_key_entries(key);
+			jlm2->next = NULL;
+			static_key_set_mod(key, jlm2);
+			static_key_set_linked(key);
+		}
 		jlm->mod = mod;
 		jlm->entries = iter;
-		jlm->next = key->next;
-		key->next = jlm;
-
-		if (jump_label_type(key) == JUMP_LABEL_ENABLE)
-			__jump_label_update(key, iter, iter_stop, JUMP_LABEL_ENABLE);
+		jlm->next = static_key_mod(key);
+		static_key_set_mod(key, jlm);
+		static_key_set_linked(key);
+
+		/* Only update if we've changed from our initial state */
+do_poke:
+		if (jump_label_type(iter) != jump_label_init_type(iter))
+			__jump_label_update(key, iter, iter_stop, true);
 	}
 
 	return 0;
@@ -328,38 +777,48 @@ static void jump_label_del_module(struct module *mod)
 	struct static_key_mod *jlm, **prev;
 
 	for (iter = iter_start; iter < iter_stop; iter++) {
-		if (iter->key == (jump_label_t)(unsigned long)key)
+		if (jump_entry_key(iter) == key)
 			continue;
 
-		key = (struct static_key *)(unsigned long)iter->key;
+		key = jump_entry_key(iter);
+
+		if (within_module((unsigned long)key, mod))
+			continue;
+
+		/* No @jlm allocated because key was sealed at init. */
+		if (static_key_sealed(key))
+			continue;
 
-		if (__module_address(iter->key) == mod)
+		/* No memory during module load */
+		if (WARN_ON(!static_key_linked(key)))
 			continue;
 
 		prev = &key->next;
-		jlm = key->next;
+		jlm = static_key_mod(key);
 
 		while (jlm && jlm->mod != mod) {
 			prev = &jlm->next;
 			jlm = jlm->next;
 		}
 
-		if (jlm) {
+		/* No memory during module load */
+		if (WARN_ON(!jlm))
+			continue;
+
+		if (prev == &key->next)
+			static_key_set_mod(key, jlm->next);
+		else
 			*prev = jlm->next;
-			kfree(jlm);
-		}
-	}
-}
 
-static void jump_label_invalidate_module_init(struct module *mod)
-{
-	struct jump_entry *iter_start = mod->jump_entries;
-	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
-	struct jump_entry *iter;
+		kfree(jlm);
 
-	for (iter = iter_start; iter < iter_stop; iter++) {
-		if (within_module_init(iter->code, mod))
-			iter->code = 0;
+		jlm = static_key_mod(key);
+		/* if only one etry is left, fold it back into the static_key */
+		if (jlm->next == NULL) {
+			static_key_set_entries(key, jlm->entries);
+			static_key_clear_linked(key);
+			kfree(jlm);
+		}
 	}
 }
 
@@ -370,30 +829,29 @@ jump_label_module_notify(struct notifier_block *self, unsigned long val,
 	struct module *mod = data;
 	int ret = 0;
 
+	cpus_read_lock();
+	jump_label_lock();
+
 	switch (val) {
 	case MODULE_STATE_COMING:
-		jump_label_lock();
 		ret = jump_label_add_module(mod);
-		if (ret)
+		if (ret) {
+			WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
 			jump_label_del_module(mod);
-		jump_label_unlock();
+		}
 		break;
 	case MODULE_STATE_GOING:
-		jump_label_lock();
 		jump_label_del_module(mod);
-		jump_label_unlock();
-		break;
-	case MODULE_STATE_LIVE:
-		jump_label_lock();
-		jump_label_invalidate_module_init(mod);
-		jump_label_unlock();
 		break;
 	}
 
+	jump_label_unlock();
+	cpus_read_unlock();
+
 	return notifier_from_errno(ret);
 }
 
-struct notifier_block jump_label_module_nb = {
+static struct notifier_block jump_label_module_nb = {
 	.notifier_call = jump_label_module_notify,
 	.priority = 1, /* higher than tracepoints */
 };
@@ -421,8 +879,9 @@ early_initcall(jump_label_init_module);
  */
 int jump_label_text_reserved(void *start, void *end)
 {
+	bool init = system_state < SYSTEM_RUNNING;
 	int ret = __jump_label_text_reserved(__start___jump_table,
-			__stop___jump_table, start, end);
+			__stop___jump_table, start, end, init);
 
 	if (ret)
 		return ret;
@@ -433,22 +892,66 @@ int jump_label_text_reserved(void *start, void *end)
 	return ret;
 }
 
-static void jump_label_update(struct static_key *key, int enable)
+static void jump_label_update(struct static_key *key)
 {
 	struct jump_entry *stop = __stop___jump_table;
-	struct jump_entry *entry = jump_label_get_entries(key);
-
+	bool init = system_state < SYSTEM_RUNNING;
+	struct jump_entry *entry;
 #ifdef CONFIG_MODULES
-	struct module *mod = __module_address((unsigned long)key);
+	struct module *mod;
 
-	__jump_label_mod_update(key, enable);
+	if (static_key_linked(key)) {
+		__jump_label_mod_update(key);
+		return;
+	}
 
-	if (mod)
-		stop = mod->jump_entries + mod->num_jump_entries;
+	scoped_guard(rcu) {
+		mod = __module_address((unsigned long)key);
+		if (mod) {
+			stop = mod->jump_entries + mod->num_jump_entries;
+			init = mod->state == MODULE_STATE_COMING;
+		}
+	}
 #endif
+	entry = static_key_entries(key);
 	/* if there are no users, entry can be NULL */
 	if (entry)
-		__jump_label_update(key, entry, stop, enable);
+		__jump_label_update(key, entry, stop, init);
 }
 
-#endif
+#ifdef CONFIG_STATIC_KEYS_SELFTEST
+static DEFINE_STATIC_KEY_TRUE(sk_true);
+static DEFINE_STATIC_KEY_FALSE(sk_false);
+
+static __init int jump_label_test(void)
+{
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		WARN_ON(static_key_enabled(&sk_true.key) != true);
+		WARN_ON(static_key_enabled(&sk_false.key) != false);
+
+		WARN_ON(!static_branch_likely(&sk_true));
+		WARN_ON(!static_branch_unlikely(&sk_true));
+		WARN_ON(static_branch_likely(&sk_false));
+		WARN_ON(static_branch_unlikely(&sk_false));
+
+		static_branch_disable(&sk_true);
+		static_branch_enable(&sk_false);
+
+		WARN_ON(static_key_enabled(&sk_true.key) == true);
+		WARN_ON(static_key_enabled(&sk_false.key) == false);
+
+		WARN_ON(static_branch_likely(&sk_true));
+		WARN_ON(static_branch_unlikely(&sk_true));
+		WARN_ON(!static_branch_likely(&sk_false));
+		WARN_ON(!static_branch_unlikely(&sk_false));
+
+		static_branch_enable(&sk_true);
+		static_branch_disable(&sk_false);
+	}
+
+	return 0;
+}
+early_initcall(jump_label_test);
+#endif /* STATIC_KEYS_SELFTEST */