| /* |
| * jump label support |
| * |
| * Copyright (C) 2009 Jason Baron <jbaron@redhat.com> |
| * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com> |
| * |
| */ |
| #include <linux/memory.h> |
| #include <linux/uaccess.h> |
| #include <linux/module.h> |
| #include <linux/list.h> |
| #include <linux/slab.h> |
| #include <linux/sort.h> |
| #include <linux/err.h> |
| #include <linux/jump_label.h> |
| |
| #ifdef HAVE_JUMP_LABEL |
| |
| /* mutex to protect coming/going of the the jump_label table */ |
| static DEFINE_MUTEX(jump_label_mutex); |
| |
| void jump_label_lock(void) |
| { |
| mutex_lock(&jump_label_mutex); |
| } |
| |
| void jump_label_unlock(void) |
| { |
| mutex_unlock(&jump_label_mutex); |
| } |
| |
| bool jump_label_enabled(struct jump_label_key *key) |
| { |
| return !!atomic_read(&key->enabled); |
| } |
| |
| 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) |
| return -1; |
| |
| if (jea->key > jeb->key) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void |
| jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) |
| { |
| unsigned long size; |
| |
| size = (((unsigned long)stop - (unsigned long)start) |
| / sizeof(struct jump_entry)); |
| sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL); |
| } |
| |
| static void jump_label_update(struct jump_label_key *key, int enable); |
| |
| void jump_label_inc(struct jump_label_key *key) |
| { |
| if (atomic_inc_not_zero(&key->enabled)) |
| return; |
| |
| jump_label_lock(); |
| if (atomic_read(&key->enabled) == 0) |
| jump_label_update(key, JUMP_LABEL_ENABLE); |
| atomic_inc(&key->enabled); |
| jump_label_unlock(); |
| } |
| EXPORT_SYMBOL_GPL(jump_label_inc); |
| |
| static void __jump_label_dec(struct jump_label_key *key, |
| unsigned long rate_limit, struct delayed_work *work) |
| { |
| if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) |
| return; |
| |
| if (rate_limit) { |
| atomic_inc(&key->enabled); |
| schedule_delayed_work(work, rate_limit); |
| } else |
| jump_label_update(key, JUMP_LABEL_DISABLE); |
| |
| jump_label_unlock(); |
| } |
| EXPORT_SYMBOL_GPL(jump_label_dec); |
| |
| static void jump_label_update_timeout(struct work_struct *work) |
| { |
| struct jump_label_key_deferred *key = |
| container_of(work, struct jump_label_key_deferred, work.work); |
| __jump_label_dec(&key->key, 0, NULL); |
| } |
| |
| void jump_label_dec(struct jump_label_key *key) |
| { |
| __jump_label_dec(key, 0, NULL); |
| } |
| |
| void jump_label_dec_deferred(struct jump_label_key_deferred *key) |
| { |
| __jump_label_dec(&key->key, key->timeout, &key->work); |
| } |
| |
| |
| void jump_label_rate_limit(struct jump_label_key_deferred *key, |
| unsigned long rl) |
| { |
| key->timeout = rl; |
| INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); |
| } |
| |
| 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) |
| 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; |
| |
| iter = iter_start; |
| while (iter < iter_stop) { |
| 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. |
| */ |
| 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); |
| } |
| |
| static void __jump_label_update(struct jump_label_key *key, |
| struct jump_entry *entry, |
| struct jump_entry *stop, int enable) |
| { |
| for (; (entry < stop) && |
| (entry->key == (jump_label_t)(unsigned long)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); |
| } |
| } |
| |
| void __init jump_label_init(void) |
| { |
| struct jump_entry *iter_start = __start___jump_table; |
| struct jump_entry *iter_stop = __stop___jump_table; |
| struct jump_label_key *key = NULL; |
| struct jump_entry *iter; |
| |
| jump_label_lock(); |
| jump_label_sort_entries(iter_start, iter_stop); |
| |
| for (iter = iter_start; iter < iter_stop; iter++) { |
| struct jump_label_key *iterk; |
| |
| iterk = (struct jump_label_key *)(unsigned long)iter->key; |
| arch_jump_label_transform_static(iter, jump_label_enabled(iterk) ? |
| JUMP_LABEL_ENABLE : JUMP_LABEL_DISABLE); |
| if (iterk == key) |
| continue; |
| |
| key = iterk; |
| key->entries = iter; |
| #ifdef CONFIG_MODULES |
| key->next = NULL; |
| #endif |
| } |
| jump_label_unlock(); |
| } |
| |
| #ifdef CONFIG_MODULES |
| |
| struct jump_label_mod { |
| struct jump_label_mod *next; |
| struct jump_entry *entries; |
| struct module *mod; |
| }; |
| |
| static int __jump_label_mod_text_reserved(void *start, void *end) |
| { |
| struct module *mod; |
| |
| mod = __module_text_address((unsigned long)start); |
| if (!mod) |
| return 0; |
| |
| WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
| |
| return __jump_label_text_reserved(mod->jump_entries, |
| mod->jump_entries + mod->num_jump_entries, |
| start, end); |
| } |
| |
| static void __jump_label_mod_update(struct jump_label_key *key, int enable) |
| { |
| struct jump_label_mod *mod = key->next; |
| |
| while (mod) { |
| struct module *m = mod->mod; |
| |
| __jump_label_update(key, mod->entries, |
| m->jump_entries + m->num_jump_entries, |
| enable); |
| mod = mod->next; |
| } |
| } |
| |
| /*** |
| * 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) |
| { |
| struct jump_entry *iter_start = mod->jump_entries; |
| struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; |
| struct jump_entry *iter; |
| |
| /* if the module doesn't have jump label entries, just return */ |
| if (iter_start == iter_stop) |
| return; |
| |
| for (iter = iter_start; iter < iter_stop; iter++) { |
| struct jump_label_key *iterk; |
| |
| iterk = (struct jump_label_key *)(unsigned long)iter->key; |
| arch_jump_label_transform_static(iter, jump_label_enabled(iterk) ? |
| JUMP_LABEL_ENABLE : JUMP_LABEL_DISABLE); |
| } |
| } |
| |
| static int jump_label_add_module(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; |
| struct jump_label_key *key = NULL; |
| struct jump_label_mod *jlm; |
| |
| /* if the module doesn't have jump label entries, just return */ |
| if (iter_start == iter_stop) |
| return 0; |
| |
| jump_label_sort_entries(iter_start, iter_stop); |
| |
| for (iter = iter_start; iter < iter_stop; iter++) { |
| if (iter->key == (jump_label_t)(unsigned long)key) |
| continue; |
| |
| key = (struct jump_label_key *)(unsigned long)iter->key; |
| |
| if (__module_address(iter->key) == mod) { |
| atomic_set(&key->enabled, 0); |
| key->entries = iter; |
| key->next = NULL; |
| continue; |
| } |
| |
| jlm = kzalloc(sizeof(struct jump_label_mod), GFP_KERNEL); |
| if (!jlm) |
| return -ENOMEM; |
| |
| jlm->mod = mod; |
| jlm->entries = iter; |
| jlm->next = key->next; |
| key->next = jlm; |
| |
| if (jump_label_enabled(key)) |
| __jump_label_update(key, iter, iter_stop, JUMP_LABEL_ENABLE); |
| } |
| |
| return 0; |
| } |
| |
| static void jump_label_del_module(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; |
| struct jump_label_key *key = NULL; |
| struct jump_label_mod *jlm, **prev; |
| |
| for (iter = iter_start; iter < iter_stop; iter++) { |
| if (iter->key == (jump_label_t)(unsigned long)key) |
| continue; |
| |
| key = (struct jump_label_key *)(unsigned long)iter->key; |
| |
| if (__module_address(iter->key) == mod) |
| continue; |
| |
| prev = &key->next; |
| jlm = key->next; |
| |
| while (jlm && jlm->mod != mod) { |
| prev = &jlm->next; |
| jlm = jlm->next; |
| } |
| |
| if (jlm) { |
| *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; |
| |
| for (iter = iter_start; iter < iter_stop; iter++) { |
| if (within_module_init(iter->code, mod)) |
| iter->code = 0; |
| } |
| } |
| |
| static int |
| jump_label_module_notify(struct notifier_block *self, unsigned long val, |
| void *data) |
| { |
| struct module *mod = data; |
| int ret = 0; |
| |
| switch (val) { |
| case MODULE_STATE_COMING: |
| jump_label_lock(); |
| ret = jump_label_add_module(mod); |
| if (ret) |
| 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; |
| } |
| |
| return notifier_from_errno(ret); |
| } |
| |
| struct notifier_block jump_label_module_nb = { |
| .notifier_call = jump_label_module_notify, |
| .priority = 1, /* higher than tracepoints */ |
| }; |
| |
| static __init int jump_label_init_module(void) |
| { |
| return register_module_notifier(&jump_label_module_nb); |
| } |
| early_initcall(jump_label_init_module); |
| |
| #endif /* CONFIG_MODULES */ |
| |
| /*** |
| * jump_label_text_reserved - check if addr range is reserved |
| * @start: start text addr |
| * @end: end text addr |
| * |
| * checks if the text addr located between @start and @end |
| * overlaps with any of the jump label patch addresses. Code |
| * that wants to modify kernel text should first verify that |
| * it does not overlap with any of the jump label addresses. |
| * Caller must hold jump_label_mutex. |
| * |
| * returns 1 if there is an overlap, 0 otherwise |
| */ |
| int jump_label_text_reserved(void *start, void *end) |
| { |
| int ret = __jump_label_text_reserved(__start___jump_table, |
| __stop___jump_table, start, end); |
| |
| if (ret) |
| return ret; |
| |
| #ifdef CONFIG_MODULES |
| ret = __jump_label_mod_text_reserved(start, end); |
| #endif |
| return ret; |
| } |
| |
| static void jump_label_update(struct jump_label_key *key, int enable) |
| { |
| struct jump_entry *entry = key->entries, *stop = __stop___jump_table; |
| |
| #ifdef CONFIG_MODULES |
| struct module *mod = __module_address((jump_label_t)key); |
| |
| __jump_label_mod_update(key, enable); |
| |
| if (mod) |
| stop = mod->jump_entries + mod->num_jump_entries; |
| #endif |
| /* if there are no users, entry can be NULL */ |
| if (entry) |
| __jump_label_update(key, entry, stop, enable); |
| } |
| |
| #endif |