Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking and atomic updates from Ingo Molnar:
 "Main changes in this cycle are:

   - Extend atomic primitives with coherent logic op primitives
     (atomic_{or,and,xor}()) and deprecate the old partial APIs
     (atomic_{set,clear}_mask())

     The old ops were incoherent with incompatible signatures across
     architectures and with incomplete support.  Now every architecture
     supports the primitives consistently (by Peter Zijlstra)

   - Generic support for 'relaxed atomics':

       - _acquire/release/relaxed() flavours of xchg(), cmpxchg() and {add,sub}_return()
       - atomic_read_acquire()
       - atomic_set_release()

     This came out of porting qwrlock code to arm64 (by Will Deacon)

   - Clean up the fragile static_key APIs that were causing repeat bugs,
     by introducing a new one:

       DEFINE_STATIC_KEY_TRUE(name);
       DEFINE_STATIC_KEY_FALSE(name);

     which define a key of different types with an initial true/false
     value.

     Then allow:

       static_branch_likely()
       static_branch_unlikely()

     to take a key of either type and emit the right instruction for the
     case.  To be able to know the 'type' of the static key we encode it
     in the jump entry (by Peter Zijlstra)

   - Static key self-tests (by Jason Baron)

   - qrwlock optimizations (by Waiman Long)

   - small futex enhancements (by Davidlohr Bueso)

   - ... and misc other changes"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (63 commits)
  jump_label/x86: Work around asm build bug on older/backported GCCs
  locking, ARM, atomics: Define our SMP atomics in terms of _relaxed() operations
  locking, include/llist: Use linux/atomic.h instead of asm/cmpxchg.h
  locking/qrwlock: Make use of _{acquire|release|relaxed}() atomics
  locking/qrwlock: Implement queue_write_unlock() using smp_store_release()
  locking/lockref: Remove homebrew cmpxchg64_relaxed() macro definition
  locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'
  locking, asm-generic: Rework atomic-long.h to avoid bulk code duplication
  locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations
  locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic
  locking/static_keys: Make verify_keys() static
  jump label, locking/static_keys: Update docs
  locking/static_keys: Provide a selftest
  jump_label: Provide a self-test
  s390/uaccess, locking/static_keys: employ static_branch_likely()
  x86, tsc, locking/static_keys: Employ static_branch_likely()
  locking/static_keys: Add selftest
  locking/static_keys: Add a new static_key interface
  locking/static_keys: Rework update logic
  locking/static_keys: Add static_key_{en,dis}able() helpers
  ...

1 files changed, 109 insertions, 49 deletions

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 52ebaca1b9fc..f7dd15d537f9 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -54,7 +54,7 @@ jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
 	sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
 }
 
-static void jump_label_update(struct static_key *key, int enable);
+static void jump_label_update(struct static_key *key);
 
 void static_key_slow_inc(struct static_key *key)
 {
@@ -63,13 +63,8 @@ void static_key_slow_inc(struct static_key *key)
 		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_inc(&key->enabled);
+	if (atomic_inc_return(&key->enabled) == 1)
+		jump_label_update(key);
 	jump_label_unlock();
 }
 EXPORT_SYMBOL_GPL(static_key_slow_inc);
@@ -87,10 +82,7 @@ static void __static_key_slow_dec(struct static_key *key,
 		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_update(key);
 	}
 	jump_label_unlock();
 }
@@ -149,7 +141,7 @@ static int __jump_label_text_reserved(struct jump_entry *iter_start,
 	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
@@ -158,37 +150,54 @@ static int __jump_label_text_reserved(struct jump_entry *iter_start,
 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
 					    enum jump_label_type type)
 {
-	arch_jump_label_transform(entry, type);	
+	arch_jump_label_transform(entry, type);
+}
+
+static inline struct jump_entry *static_key_entries(struct static_key *key)
+{
+	return (struct jump_entry *)((unsigned long)key->entries & ~JUMP_TYPE_MASK);
+}
+
+static inline bool static_key_type(struct static_key *key)
+{
+	return (unsigned long)key->entries & JUMP_TYPE_MASK;
+}
+
+static inline struct static_key *jump_entry_key(struct jump_entry *entry)
+{
+	return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static bool jump_entry_branch(struct jump_entry *entry)
+{
+	return (unsigned long)entry->key & 1UL;
+}
+
+static enum jump_label_type jump_label_type(struct jump_entry *entry)
+{
+	struct static_key *key = jump_entry_key(entry);
+	bool enabled = static_key_enabled(key);
+	bool branch = jump_entry_branch(entry);
+
+	/* See the comment in linux/jump_label.h */
+	return enabled ^ branch;
 }
 
 static void __jump_label_update(struct static_key *key,
 				struct jump_entry *entry,
-				struct jump_entry *stop, int enable)
+				struct jump_entry *stop)
 {
-	for (; (entry < stop) &&
-	      (entry->key == (jump_label_t)(unsigned long)key);
-	      entry++) {
+	for (; (entry < stop) && (jump_entry_key(entry) == key); 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().
 		 */
 		if (entry->code && kernel_text_address(entry->code))
-			arch_jump_label_transform(entry, enable);
+			arch_jump_label_transform(entry, jump_label_type(entry));
 	}
 }
 
-static enum jump_label_type jump_label_type(struct static_key *key)
-{
-	bool true_branch = jump_label_get_branch_default(key);
-	bool state = static_key_enabled(key);
-
-	if ((!true_branch && state) || (true_branch && !state))
-		return JUMP_LABEL_ENABLE;
-
-	return JUMP_LABEL_DISABLE;
-}
-
 void __init jump_label_init(void)
 {
 	struct jump_entry *iter_start = __start___jump_table;
@@ -202,8 +211,11 @@ void __init jump_label_init(void)
 	for (iter = iter_start; iter < iter_stop; iter++) {
 		struct static_key *iterk;
 
-		iterk = (struct static_key *)(unsigned long)iter->key;
-		arch_jump_label_transform_static(iter, jump_label_type(iterk));
+		/* rewrite NOPs */
+		if (jump_label_type(iter) == JUMP_LABEL_NOP)
+			arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
+
+		iterk = jump_entry_key(iter);
 		if (iterk == key)
 			continue;
 
@@ -222,6 +234,16 @@ void __init jump_label_init(void)
 
 #ifdef CONFIG_MODULES
 
+static 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_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;
@@ -243,17 +265,15 @@ static int __jump_label_mod_text_reserved(void *start, void *end)
 				start, end);
 }
 
-static void __jump_label_mod_update(struct static_key *key, int enable)
+static void __jump_label_mod_update(struct static_key *key)
 {
-	struct static_key_mod *mod = key->next;
+	struct static_key_mod *mod;
 
-	while (mod) {
+	for (mod = key->next; mod; mod = mod->next) {
 		struct module *m = mod->mod;
 
 		__jump_label_update(key, mod->entries,
-				    m->jump_entries + m->num_jump_entries,
-				    enable);
-		mod = mod->next;
+				    m->jump_entries + m->num_jump_entries);
 	}
 }
 
@@ -276,7 +296,9 @@ void jump_label_apply_nops(struct module *mod)
 		return;
 
 	for (iter = iter_start; iter < iter_stop; iter++) {
-		arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
+		/* Only write NOPs for arch_branch_static(). */
+		if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
+			arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 	}
 }
 
@@ -297,7 +319,7 @@ static int jump_label_add_module(struct module *mod)
 	for (iter = iter_start; iter < iter_stop; iter++) {
 		struct static_key *iterk;
 
-		iterk = (struct static_key *)(unsigned long)iter->key;
+		iterk = jump_entry_key(iter);
 		if (iterk == key)
 			continue;
 
@@ -318,8 +340,9 @@ static int jump_label_add_module(struct module *mod)
 		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);
+		/* Only update if we've changed from our initial state */
+		if (jump_label_type(iter) != jump_label_init_type(iter))
+			__jump_label_update(key, iter, iter_stop);
 	}
 
 	return 0;
@@ -334,10 +357,10 @@ 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(iter->key, mod))
 			continue;
@@ -439,14 +462,14 @@ 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);
+	struct jump_entry *entry = static_key_entries(key);
 #ifdef CONFIG_MODULES
 	struct module *mod;
 
-	__jump_label_mod_update(key, enable);
+	__jump_label_mod_update(key);
 
 	preempt_disable();
 	mod = __module_address((unsigned long)key);
@@ -456,7 +479,44 @@ static void jump_label_update(struct static_key *key, int enable)
 #endif
 	/* if there are no users, entry can be NULL */
 	if (entry)
-		__jump_label_update(key, entry, stop, enable);
+		__jump_label_update(key, entry, stop);
 }
 
-#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;
+}
+late_initcall(jump_label_test);
+#endif /* STATIC_KEYS_SELFTEST */
+
+#endif /* HAVE_JUMP_LABEL */