4 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
5 * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com>
8 #include <linux/memory.h>
9 #include <linux/uaccess.h>
10 #include <linux/module.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 #include <linux/sort.h>
14 #include <linux/err.h>
15 #include <linux/jump_label.h>
17 #ifdef HAVE_JUMP_LABEL
19 /* mutex to protect coming/going of the the jump_label table */
20 static DEFINE_MUTEX(jump_label_mutex);
22 void jump_label_lock(void)
24 mutex_lock(&jump_label_mutex);
27 void jump_label_unlock(void)
29 mutex_unlock(&jump_label_mutex);
32 bool jump_label_enabled(struct jump_label_key *key)
34 return !!atomic_read(&key->enabled);
37 static int jump_label_cmp(const void *a, const void *b)
39 const struct jump_entry *jea = a;
40 const struct jump_entry *jeb = b;
42 if (jea->key < jeb->key)
45 if (jea->key > jeb->key)
52 jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
56 size = (((unsigned long)stop - (unsigned long)start)
57 / sizeof(struct jump_entry));
58 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
61 static void jump_label_update(struct jump_label_key *key, int enable);
63 void jump_label_inc(struct jump_label_key *key)
65 if (atomic_inc_not_zero(&key->enabled))
69 if (atomic_read(&key->enabled) == 0)
70 jump_label_update(key, JUMP_LABEL_ENABLE);
71 atomic_inc(&key->enabled);
74 EXPORT_SYMBOL_GPL(jump_label_inc);
76 void jump_label_dec(struct jump_label_key *key)
78 if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex))
81 jump_label_update(key, JUMP_LABEL_DISABLE);
84 EXPORT_SYMBOL_GPL(jump_label_dec);
86 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
88 if (entry->code <= (unsigned long)end &&
89 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
95 static int __jump_label_text_reserved(struct jump_entry *iter_start,
96 struct jump_entry *iter_stop, void *start, void *end)
98 struct jump_entry *iter;
101 while (iter < iter_stop) {
102 if (addr_conflict(iter, start, end))
111 * Update code which is definitely not currently executing.
112 * Architectures which need heavyweight synchronization to modify
113 * running code can override this to make the non-live update case
116 void __weak arch_jump_label_transform_static(struct jump_entry *entry,
117 enum jump_label_type type)
119 arch_jump_label_transform(entry, type);
122 static void __jump_label_update(struct jump_label_key *key,
123 struct jump_entry *entry,
124 struct jump_entry *stop, int enable)
126 for (; (entry < stop) &&
127 (entry->key == (jump_label_t)(unsigned long)key);
130 * entry->code set to 0 invalidates module init text sections
131 * kernel_text_address() verifies we are not in core kernel
132 * init code, see jump_label_invalidate_module_init().
134 if (entry->code && kernel_text_address(entry->code))
135 arch_jump_label_transform(entry, enable);
139 void __init jump_label_init(void)
141 struct jump_entry *iter_start = __start___jump_table;
142 struct jump_entry *iter_stop = __stop___jump_table;
143 struct jump_label_key *key = NULL;
144 struct jump_entry *iter;
147 jump_label_sort_entries(iter_start, iter_stop);
149 for (iter = iter_start; iter < iter_stop; iter++) {
150 struct jump_label_key *iterk;
152 iterk = (struct jump_label_key *)(unsigned long)iter->key;
153 arch_jump_label_transform_static(iter, jump_label_enabled(iterk) ?
154 JUMP_LABEL_ENABLE : JUMP_LABEL_DISABLE);
160 #ifdef CONFIG_MODULES
167 #ifdef CONFIG_MODULES
169 struct jump_label_mod {
170 struct jump_label_mod *next;
171 struct jump_entry *entries;
175 static int __jump_label_mod_text_reserved(void *start, void *end)
179 mod = __module_text_address((unsigned long)start);
183 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
185 return __jump_label_text_reserved(mod->jump_entries,
186 mod->jump_entries + mod->num_jump_entries,
190 static void __jump_label_mod_update(struct jump_label_key *key, int enable)
192 struct jump_label_mod *mod = key->next;
195 struct module *m = mod->mod;
197 __jump_label_update(key, mod->entries,
198 m->jump_entries + m->num_jump_entries,
205 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
206 * @mod: module to patch
208 * Allow for run-time selection of the optimal nops. Before the module
209 * loads patch these with arch_get_jump_label_nop(), which is specified by
210 * the arch specific jump label code.
212 void jump_label_apply_nops(struct module *mod)
214 struct jump_entry *iter_start = mod->jump_entries;
215 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
216 struct jump_entry *iter;
218 /* if the module doesn't have jump label entries, just return */
219 if (iter_start == iter_stop)
222 for (iter = iter_start; iter < iter_stop; iter++)
223 arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
226 static int jump_label_add_module(struct module *mod)
228 struct jump_entry *iter_start = mod->jump_entries;
229 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
230 struct jump_entry *iter;
231 struct jump_label_key *key = NULL;
232 struct jump_label_mod *jlm;
234 /* if the module doesn't have jump label entries, just return */
235 if (iter_start == iter_stop)
238 jump_label_sort_entries(iter_start, iter_stop);
240 for (iter = iter_start; iter < iter_stop; iter++) {
241 if (iter->key == (jump_label_t)(unsigned long)key)
244 key = (struct jump_label_key *)(unsigned long)iter->key;
246 if (__module_address(iter->key) == mod) {
247 atomic_set(&key->enabled, 0);
253 jlm = kzalloc(sizeof(struct jump_label_mod), GFP_KERNEL);
259 jlm->next = key->next;
262 if (jump_label_enabled(key))
263 __jump_label_update(key, iter, iter_stop,
270 static void jump_label_del_module(struct module *mod)
272 struct jump_entry *iter_start = mod->jump_entries;
273 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
274 struct jump_entry *iter;
275 struct jump_label_key *key = NULL;
276 struct jump_label_mod *jlm, **prev;
278 for (iter = iter_start; iter < iter_stop; iter++) {
279 if (iter->key == (jump_label_t)(unsigned long)key)
282 key = (struct jump_label_key *)(unsigned long)iter->key;
284 if (__module_address(iter->key) == mod)
290 while (jlm && jlm->mod != mod) {
302 static void jump_label_invalidate_module_init(struct module *mod)
304 struct jump_entry *iter_start = mod->jump_entries;
305 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
306 struct jump_entry *iter;
308 for (iter = iter_start; iter < iter_stop; iter++) {
309 if (within_module_init(iter->code, mod))
315 jump_label_module_notify(struct notifier_block *self, unsigned long val,
318 struct module *mod = data;
322 case MODULE_STATE_COMING:
324 ret = jump_label_add_module(mod);
326 jump_label_del_module(mod);
329 case MODULE_STATE_GOING:
331 jump_label_del_module(mod);
334 case MODULE_STATE_LIVE:
336 jump_label_invalidate_module_init(mod);
341 return notifier_from_errno(ret);
344 struct notifier_block jump_label_module_nb = {
345 .notifier_call = jump_label_module_notify,
346 .priority = 1, /* higher than tracepoints */
349 static __init int jump_label_init_module(void)
351 return register_module_notifier(&jump_label_module_nb);
353 early_initcall(jump_label_init_module);
355 #endif /* CONFIG_MODULES */
358 * jump_label_text_reserved - check if addr range is reserved
359 * @start: start text addr
360 * @end: end text addr
362 * checks if the text addr located between @start and @end
363 * overlaps with any of the jump label patch addresses. Code
364 * that wants to modify kernel text should first verify that
365 * it does not overlap with any of the jump label addresses.
366 * Caller must hold jump_label_mutex.
368 * returns 1 if there is an overlap, 0 otherwise
370 int jump_label_text_reserved(void *start, void *end)
372 int ret = __jump_label_text_reserved(__start___jump_table,
373 __stop___jump_table, start, end);
378 #ifdef CONFIG_MODULES
379 ret = __jump_label_mod_text_reserved(start, end);
384 static void jump_label_update(struct jump_label_key *key, int enable)
386 struct jump_entry *entry = key->entries, *stop = __stop___jump_table;
388 #ifdef CONFIG_MODULES
389 struct module *mod = __module_address((jump_label_t)key);
391 __jump_label_mod_update(key, enable);
394 stop = mod->jump_entries + mod->num_jump_entries;
396 /* if there are no users, entry can be NULL */
398 __jump_label_update(key, entry, stop, enable);