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_add_return(1, &key->enabled) == 1)
70 jump_label_update(key, JUMP_LABEL_ENABLE);
74 void jump_label_dec(struct jump_label_key *key)
76 if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex))
79 jump_label_update(key, JUMP_LABEL_DISABLE);
83 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
85 if (entry->code <= (unsigned long)end &&
86 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
92 static int __jump_label_text_reserved(struct jump_entry *iter_start,
93 struct jump_entry *iter_stop, void *start, void *end)
95 struct jump_entry *iter;
98 while (iter < iter_stop) {
99 if (addr_conflict(iter, start, end))
107 static void __jump_label_update(struct jump_label_key *key,
108 struct jump_entry *entry, int enable)
110 for (; entry->key == (jump_label_t)(unsigned long)key; entry++) {
112 * entry->code set to 0 invalidates module init text sections
113 * kernel_text_address() verifies we are not in core kernel
114 * init code, see jump_label_invalidate_module_init().
116 if (entry->code && kernel_text_address(entry->code))
117 arch_jump_label_transform(entry, enable);
122 * Not all archs need this.
124 void __weak arch_jump_label_text_poke_early(jump_label_t addr)
128 static __init int jump_label_init(void)
130 struct jump_entry *iter_start = __start___jump_table;
131 struct jump_entry *iter_stop = __stop___jump_table;
132 struct jump_label_key *key = NULL;
133 struct jump_entry *iter;
136 jump_label_sort_entries(iter_start, iter_stop);
138 for (iter = iter_start; iter < iter_stop; iter++) {
139 arch_jump_label_text_poke_early(iter->code);
140 if (iter->key == (jump_label_t)(unsigned long)key)
143 key = (struct jump_label_key *)(unsigned long)iter->key;
144 atomic_set(&key->enabled, 0);
146 #ifdef CONFIG_MODULES
154 early_initcall(jump_label_init);
156 #ifdef CONFIG_MODULES
158 struct jump_label_mod {
159 struct jump_label_mod *next;
160 struct jump_entry *entries;
164 static int __jump_label_mod_text_reserved(void *start, void *end)
168 mod = __module_text_address((unsigned long)start);
172 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
174 return __jump_label_text_reserved(mod->jump_entries,
175 mod->jump_entries + mod->num_jump_entries,
179 static void __jump_label_mod_update(struct jump_label_key *key, int enable)
181 struct jump_label_mod *mod = key->next;
184 __jump_label_update(key, mod->entries, enable);
190 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
191 * @mod: module to patch
193 * Allow for run-time selection of the optimal nops. Before the module
194 * loads patch these with arch_get_jump_label_nop(), which is specified by
195 * the arch specific jump label code.
197 void jump_label_apply_nops(struct module *mod)
199 struct jump_entry *iter_start = mod->jump_entries;
200 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
201 struct jump_entry *iter;
203 /* if the module doesn't have jump label entries, just return */
204 if (iter_start == iter_stop)
207 for (iter = iter_start; iter < iter_stop; iter++)
208 arch_jump_label_text_poke_early(iter->code);
211 static int jump_label_add_module(struct module *mod)
213 struct jump_entry *iter_start = mod->jump_entries;
214 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
215 struct jump_entry *iter;
216 struct jump_label_key *key = NULL;
217 struct jump_label_mod *jlm;
219 /* if the module doesn't have jump label entries, just return */
220 if (iter_start == iter_stop)
223 jump_label_sort_entries(iter_start, iter_stop);
225 for (iter = iter_start; iter < iter_stop; iter++) {
226 if (iter->key == (jump_label_t)(unsigned long)key)
229 key = (struct jump_label_key *)(unsigned long)iter->key;
231 if (__module_address(iter->key) == mod) {
232 atomic_set(&key->enabled, 0);
238 jlm = kzalloc(sizeof(struct jump_label_mod), GFP_KERNEL);
244 jlm->next = key->next;
247 if (jump_label_enabled(key))
248 __jump_label_update(key, iter, JUMP_LABEL_ENABLE);
254 static void jump_label_del_module(struct module *mod)
256 struct jump_entry *iter_start = mod->jump_entries;
257 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
258 struct jump_entry *iter;
259 struct jump_label_key *key = NULL;
260 struct jump_label_mod *jlm, **prev;
262 for (iter = iter_start; iter < iter_stop; iter++) {
263 if (iter->key == (jump_label_t)(unsigned long)key)
266 key = (struct jump_label_key *)(unsigned long)iter->key;
268 if (__module_address(iter->key) == mod)
274 while (jlm && jlm->mod != mod) {
286 static void jump_label_invalidate_module_init(struct module *mod)
288 struct jump_entry *iter_start = mod->jump_entries;
289 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
290 struct jump_entry *iter;
292 for (iter = iter_start; iter < iter_stop; iter++) {
293 if (within_module_init(iter->code, mod))
299 jump_label_module_notify(struct notifier_block *self, unsigned long val,
302 struct module *mod = data;
306 case MODULE_STATE_COMING:
308 ret = jump_label_add_module(mod);
310 jump_label_del_module(mod);
313 case MODULE_STATE_GOING:
315 jump_label_del_module(mod);
318 case MODULE_STATE_LIVE:
320 jump_label_invalidate_module_init(mod);
325 return notifier_from_errno(ret);
328 struct notifier_block jump_label_module_nb = {
329 .notifier_call = jump_label_module_notify,
330 .priority = 1, /* higher than tracepoints */
333 static __init int jump_label_init_module(void)
335 return register_module_notifier(&jump_label_module_nb);
337 early_initcall(jump_label_init_module);
339 #endif /* CONFIG_MODULES */
342 * jump_label_text_reserved - check if addr range is reserved
343 * @start: start text addr
344 * @end: end text addr
346 * checks if the text addr located between @start and @end
347 * overlaps with any of the jump label patch addresses. Code
348 * that wants to modify kernel text should first verify that
349 * it does not overlap with any of the jump label addresses.
350 * Caller must hold jump_label_mutex.
352 * returns 1 if there is an overlap, 0 otherwise
354 int jump_label_text_reserved(void *start, void *end)
356 int ret = __jump_label_text_reserved(__start___jump_table,
357 __stop___jump_table, start, end);
362 #ifdef CONFIG_MODULES
363 ret = __jump_label_mod_text_reserved(start, end);
368 static void jump_label_update(struct jump_label_key *key, int enable)
370 struct jump_entry *entry = key->entries;
372 /* if there are no users, entry can be NULL */
374 __jump_label_update(key, entry, enable);
376 #ifdef CONFIG_MODULES
377 __jump_label_mod_update(key, enable);