/* * 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/static_key.h>#include <linux/jump_label_ratelimit.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);} 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 voidjump_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 static_key *key, int enable); void static_key_slow_inc(struct static_key *key){	STATIC_KEY_CHECK_USE();	if (atomic_inc_not_zero(&key->enabled))		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);	jump_label_unlock();}EXPORT_SYMBOL_GPL(static_key_slow_inc); static void __static_key_slow_dec(struct static_key *key,		unsigned long rate_limit, struct delayed_work *work){	if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {		WARN(atomic_read(&key->enabled) < 0,		     "jump label: negative count!\n");		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_unlock();} static 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);} void static_key_slow_dec(struct static_key *key){	STATIC_KEY_CHECK_USE();	__static_key_slow_dec(key, 0, NULL);}EXPORT_SYMBOL_GPL(static_key_slow_dec); void static_key_slow_dec_deferred(struct static_key_deferred *key){	STATIC_KEY_CHECK_USE();	__static_key_slow_dec(&key->key, key->timeout, &key->work);}EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); void jump_label_rate_limit(struct static_key_deferred *key,		unsigned long rl){	STATIC_KEY_CHECK_USE();	key->timeout = rl;	INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);}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)		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 static_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);	}} 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;	struct jump_entry *iter_stop = __stop___jump_table;	struct static_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 static_key *iterk; 		iterk = (struct static_key *)(unsigned long)iter->key;		arch_jump_label_transform_static(iter, jump_label_type(iterk));		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_initialized = true;	jump_label_unlock();} #ifdef CONFIG_MODULES struct static_key_mod {	struct static_key_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 static_key *key, int enable){	struct static_key_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++) {		arch_jump_label_transform_static(iter, 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 static_key *key = NULL;	struct static_key_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++) {		struct static_key *iterk; 		iterk = (struct static_key *)(unsigned long)iter->key;		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;			continue;		}		jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);		if (!jlm)			return -ENOMEM;		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);	} 	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 static_key *key = NULL;	struct static_key_mod *jlm, **prev; 	for (iter = iter_start; iter < iter_stop; iter++) {		if (iter->key == (jump_label_t)(unsigned long)key)			continue; 		key = (struct static_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 intjump_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 static_key *key, int enable){	struct jump_entry *stop = __stop___jump_table;	struct jump_entry *entry = jump_label_get_entries(key); #ifdef CONFIG_MODULES	struct module *mod = __module_address((unsigned long)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