From 8d91c1e411f55d7ea91b1183a2e9f8088fb4d5be Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?= Date: Tue, 15 Dec 2015 14:52:16 -0300 Subject: Linux-libre 4.3.2-gnu --- kernel/jump_label.c | 158 ++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 109 insertions(+), 49 deletions(-) (limited to 'kernel/jump_label.c') diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 52ebaca1b..f7dd15d53 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 */ -- cgit v1.2.3