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Diffstat (limited to 'kernel/jump_label.c')
-rw-r--r--kernel/jump_label.c158
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 */