Loading...
1/*
2 * jump label support
3 *
4 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
5 * Copyright (C) 2011 Peter Zijlstra
6 *
7 */
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/static_key.h>
16#include <linux/jump_label_ratelimit.h>
17
18#ifdef HAVE_JUMP_LABEL
19
20/* mutex to protect coming/going of the the jump_label table */
21static DEFINE_MUTEX(jump_label_mutex);
22
23void jump_label_lock(void)
24{
25 mutex_lock(&jump_label_mutex);
26}
27
28void jump_label_unlock(void)
29{
30 mutex_unlock(&jump_label_mutex);
31}
32
33static int jump_label_cmp(const void *a, const void *b)
34{
35 const struct jump_entry *jea = a;
36 const struct jump_entry *jeb = b;
37
38 if (jea->key < jeb->key)
39 return -1;
40
41 if (jea->key > jeb->key)
42 return 1;
43
44 return 0;
45}
46
47static void
48jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
49{
50 unsigned long size;
51
52 size = (((unsigned long)stop - (unsigned long)start)
53 / sizeof(struct jump_entry));
54 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
55}
56
57static void jump_label_update(struct static_key *key);
58
59void static_key_slow_inc(struct static_key *key)
60{
61 STATIC_KEY_CHECK_USE();
62 if (atomic_inc_not_zero(&key->enabled))
63 return;
64
65 jump_label_lock();
66 if (atomic_inc_return(&key->enabled) == 1)
67 jump_label_update(key);
68 jump_label_unlock();
69}
70EXPORT_SYMBOL_GPL(static_key_slow_inc);
71
72static void __static_key_slow_dec(struct static_key *key,
73 unsigned long rate_limit, struct delayed_work *work)
74{
75 if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
76 WARN(atomic_read(&key->enabled) < 0,
77 "jump label: negative count!\n");
78 return;
79 }
80
81 if (rate_limit) {
82 atomic_inc(&key->enabled);
83 schedule_delayed_work(work, rate_limit);
84 } else {
85 jump_label_update(key);
86 }
87 jump_label_unlock();
88}
89
90static void jump_label_update_timeout(struct work_struct *work)
91{
92 struct static_key_deferred *key =
93 container_of(work, struct static_key_deferred, work.work);
94 __static_key_slow_dec(&key->key, 0, NULL);
95}
96
97void static_key_slow_dec(struct static_key *key)
98{
99 STATIC_KEY_CHECK_USE();
100 __static_key_slow_dec(key, 0, NULL);
101}
102EXPORT_SYMBOL_GPL(static_key_slow_dec);
103
104void static_key_slow_dec_deferred(struct static_key_deferred *key)
105{
106 STATIC_KEY_CHECK_USE();
107 __static_key_slow_dec(&key->key, key->timeout, &key->work);
108}
109EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
110
111void jump_label_rate_limit(struct static_key_deferred *key,
112 unsigned long rl)
113{
114 STATIC_KEY_CHECK_USE();
115 key->timeout = rl;
116 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
117}
118EXPORT_SYMBOL_GPL(jump_label_rate_limit);
119
120static int addr_conflict(struct jump_entry *entry, void *start, void *end)
121{
122 if (entry->code <= (unsigned long)end &&
123 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
124 return 1;
125
126 return 0;
127}
128
129static int __jump_label_text_reserved(struct jump_entry *iter_start,
130 struct jump_entry *iter_stop, void *start, void *end)
131{
132 struct jump_entry *iter;
133
134 iter = iter_start;
135 while (iter < iter_stop) {
136 if (addr_conflict(iter, start, end))
137 return 1;
138 iter++;
139 }
140
141 return 0;
142}
143
144/*
145 * Update code which is definitely not currently executing.
146 * Architectures which need heavyweight synchronization to modify
147 * running code can override this to make the non-live update case
148 * cheaper.
149 */
150void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
151 enum jump_label_type type)
152{
153 arch_jump_label_transform(entry, type);
154}
155
156static inline struct jump_entry *static_key_entries(struct static_key *key)
157{
158 return (struct jump_entry *)((unsigned long)key->entries & ~JUMP_TYPE_MASK);
159}
160
161static inline bool static_key_type(struct static_key *key)
162{
163 return (unsigned long)key->entries & JUMP_TYPE_MASK;
164}
165
166static inline struct static_key *jump_entry_key(struct jump_entry *entry)
167{
168 return (struct static_key *)((unsigned long)entry->key & ~1UL);
169}
170
171static bool jump_entry_branch(struct jump_entry *entry)
172{
173 return (unsigned long)entry->key & 1UL;
174}
175
176static enum jump_label_type jump_label_type(struct jump_entry *entry)
177{
178 struct static_key *key = jump_entry_key(entry);
179 bool enabled = static_key_enabled(key);
180 bool branch = jump_entry_branch(entry);
181
182 /* See the comment in linux/jump_label.h */
183 return enabled ^ branch;
184}
185
186static void __jump_label_update(struct static_key *key,
187 struct jump_entry *entry,
188 struct jump_entry *stop)
189{
190 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
191 /*
192 * entry->code set to 0 invalidates module init text sections
193 * kernel_text_address() verifies we are not in core kernel
194 * init code, see jump_label_invalidate_module_init().
195 */
196 if (entry->code && kernel_text_address(entry->code))
197 arch_jump_label_transform(entry, jump_label_type(entry));
198 }
199}
200
201void __init jump_label_init(void)
202{
203 struct jump_entry *iter_start = __start___jump_table;
204 struct jump_entry *iter_stop = __stop___jump_table;
205 struct static_key *key = NULL;
206 struct jump_entry *iter;
207
208 jump_label_lock();
209 jump_label_sort_entries(iter_start, iter_stop);
210
211 for (iter = iter_start; iter < iter_stop; iter++) {
212 struct static_key *iterk;
213
214 /* rewrite NOPs */
215 if (jump_label_type(iter) == JUMP_LABEL_NOP)
216 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
217
218 iterk = jump_entry_key(iter);
219 if (iterk == key)
220 continue;
221
222 key = iterk;
223 /*
224 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
225 */
226 *((unsigned long *)&key->entries) += (unsigned long)iter;
227#ifdef CONFIG_MODULES
228 key->next = NULL;
229#endif
230 }
231 static_key_initialized = true;
232 jump_label_unlock();
233}
234
235#ifdef CONFIG_MODULES
236
237static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
238{
239 struct static_key *key = jump_entry_key(entry);
240 bool type = static_key_type(key);
241 bool branch = jump_entry_branch(entry);
242
243 /* See the comment in linux/jump_label.h */
244 return type ^ branch;
245}
246
247struct static_key_mod {
248 struct static_key_mod *next;
249 struct jump_entry *entries;
250 struct module *mod;
251};
252
253static int __jump_label_mod_text_reserved(void *start, void *end)
254{
255 struct module *mod;
256
257 mod = __module_text_address((unsigned long)start);
258 if (!mod)
259 return 0;
260
261 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
262
263 return __jump_label_text_reserved(mod->jump_entries,
264 mod->jump_entries + mod->num_jump_entries,
265 start, end);
266}
267
268static void __jump_label_mod_update(struct static_key *key)
269{
270 struct static_key_mod *mod;
271
272 for (mod = key->next; mod; mod = mod->next) {
273 struct module *m = mod->mod;
274
275 __jump_label_update(key, mod->entries,
276 m->jump_entries + m->num_jump_entries);
277 }
278}
279
280/***
281 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
282 * @mod: module to patch
283 *
284 * Allow for run-time selection of the optimal nops. Before the module
285 * loads patch these with arch_get_jump_label_nop(), which is specified by
286 * the arch specific jump label code.
287 */
288void jump_label_apply_nops(struct module *mod)
289{
290 struct jump_entry *iter_start = mod->jump_entries;
291 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
292 struct jump_entry *iter;
293
294 /* if the module doesn't have jump label entries, just return */
295 if (iter_start == iter_stop)
296 return;
297
298 for (iter = iter_start; iter < iter_stop; iter++) {
299 /* Only write NOPs for arch_branch_static(). */
300 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
301 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
302 }
303}
304
305static int jump_label_add_module(struct module *mod)
306{
307 struct jump_entry *iter_start = mod->jump_entries;
308 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
309 struct jump_entry *iter;
310 struct static_key *key = NULL;
311 struct static_key_mod *jlm;
312
313 /* if the module doesn't have jump label entries, just return */
314 if (iter_start == iter_stop)
315 return 0;
316
317 jump_label_sort_entries(iter_start, iter_stop);
318
319 for (iter = iter_start; iter < iter_stop; iter++) {
320 struct static_key *iterk;
321
322 iterk = jump_entry_key(iter);
323 if (iterk == key)
324 continue;
325
326 key = iterk;
327 if (within_module(iter->key, mod)) {
328 /*
329 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
330 */
331 *((unsigned long *)&key->entries) += (unsigned long)iter;
332 key->next = NULL;
333 continue;
334 }
335 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
336 if (!jlm)
337 return -ENOMEM;
338 jlm->mod = mod;
339 jlm->entries = iter;
340 jlm->next = key->next;
341 key->next = jlm;
342
343 /* Only update if we've changed from our initial state */
344 if (jump_label_type(iter) != jump_label_init_type(iter))
345 __jump_label_update(key, iter, iter_stop);
346 }
347
348 return 0;
349}
350
351static void jump_label_del_module(struct module *mod)
352{
353 struct jump_entry *iter_start = mod->jump_entries;
354 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
355 struct jump_entry *iter;
356 struct static_key *key = NULL;
357 struct static_key_mod *jlm, **prev;
358
359 for (iter = iter_start; iter < iter_stop; iter++) {
360 if (jump_entry_key(iter) == key)
361 continue;
362
363 key = jump_entry_key(iter);
364
365 if (within_module(iter->key, mod))
366 continue;
367
368 prev = &key->next;
369 jlm = key->next;
370
371 while (jlm && jlm->mod != mod) {
372 prev = &jlm->next;
373 jlm = jlm->next;
374 }
375
376 if (jlm) {
377 *prev = jlm->next;
378 kfree(jlm);
379 }
380 }
381}
382
383static void jump_label_invalidate_module_init(struct module *mod)
384{
385 struct jump_entry *iter_start = mod->jump_entries;
386 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
387 struct jump_entry *iter;
388
389 for (iter = iter_start; iter < iter_stop; iter++) {
390 if (within_module_init(iter->code, mod))
391 iter->code = 0;
392 }
393}
394
395static int
396jump_label_module_notify(struct notifier_block *self, unsigned long val,
397 void *data)
398{
399 struct module *mod = data;
400 int ret = 0;
401
402 switch (val) {
403 case MODULE_STATE_COMING:
404 jump_label_lock();
405 ret = jump_label_add_module(mod);
406 if (ret)
407 jump_label_del_module(mod);
408 jump_label_unlock();
409 break;
410 case MODULE_STATE_GOING:
411 jump_label_lock();
412 jump_label_del_module(mod);
413 jump_label_unlock();
414 break;
415 case MODULE_STATE_LIVE:
416 jump_label_lock();
417 jump_label_invalidate_module_init(mod);
418 jump_label_unlock();
419 break;
420 }
421
422 return notifier_from_errno(ret);
423}
424
425struct notifier_block jump_label_module_nb = {
426 .notifier_call = jump_label_module_notify,
427 .priority = 1, /* higher than tracepoints */
428};
429
430static __init int jump_label_init_module(void)
431{
432 return register_module_notifier(&jump_label_module_nb);
433}
434early_initcall(jump_label_init_module);
435
436#endif /* CONFIG_MODULES */
437
438/***
439 * jump_label_text_reserved - check if addr range is reserved
440 * @start: start text addr
441 * @end: end text addr
442 *
443 * checks if the text addr located between @start and @end
444 * overlaps with any of the jump label patch addresses. Code
445 * that wants to modify kernel text should first verify that
446 * it does not overlap with any of the jump label addresses.
447 * Caller must hold jump_label_mutex.
448 *
449 * returns 1 if there is an overlap, 0 otherwise
450 */
451int jump_label_text_reserved(void *start, void *end)
452{
453 int ret = __jump_label_text_reserved(__start___jump_table,
454 __stop___jump_table, start, end);
455
456 if (ret)
457 return ret;
458
459#ifdef CONFIG_MODULES
460 ret = __jump_label_mod_text_reserved(start, end);
461#endif
462 return ret;
463}
464
465static void jump_label_update(struct static_key *key)
466{
467 struct jump_entry *stop = __stop___jump_table;
468 struct jump_entry *entry = static_key_entries(key);
469#ifdef CONFIG_MODULES
470 struct module *mod;
471
472 __jump_label_mod_update(key);
473
474 preempt_disable();
475 mod = __module_address((unsigned long)key);
476 if (mod)
477 stop = mod->jump_entries + mod->num_jump_entries;
478 preempt_enable();
479#endif
480 /* if there are no users, entry can be NULL */
481 if (entry)
482 __jump_label_update(key, entry, stop);
483}
484
485#ifdef CONFIG_STATIC_KEYS_SELFTEST
486static DEFINE_STATIC_KEY_TRUE(sk_true);
487static DEFINE_STATIC_KEY_FALSE(sk_false);
488
489static __init int jump_label_test(void)
490{
491 int i;
492
493 for (i = 0; i < 2; i++) {
494 WARN_ON(static_key_enabled(&sk_true.key) != true);
495 WARN_ON(static_key_enabled(&sk_false.key) != false);
496
497 WARN_ON(!static_branch_likely(&sk_true));
498 WARN_ON(!static_branch_unlikely(&sk_true));
499 WARN_ON(static_branch_likely(&sk_false));
500 WARN_ON(static_branch_unlikely(&sk_false));
501
502 static_branch_disable(&sk_true);
503 static_branch_enable(&sk_false);
504
505 WARN_ON(static_key_enabled(&sk_true.key) == true);
506 WARN_ON(static_key_enabled(&sk_false.key) == false);
507
508 WARN_ON(static_branch_likely(&sk_true));
509 WARN_ON(static_branch_unlikely(&sk_true));
510 WARN_ON(!static_branch_likely(&sk_false));
511 WARN_ON(!static_branch_unlikely(&sk_false));
512
513 static_branch_enable(&sk_true);
514 static_branch_disable(&sk_false);
515 }
516
517 return 0;
518}
519late_initcall(jump_label_test);
520#endif /* STATIC_KEYS_SELFTEST */
521
522#endif /* HAVE_JUMP_LABEL */
1/*
2 * jump label support
3 *
4 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
5 * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com>
6 *
7 */
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/static_key.h>
16
17#ifdef HAVE_JUMP_LABEL
18
19/* mutex to protect coming/going of the the jump_label table */
20static DEFINE_MUTEX(jump_label_mutex);
21
22void jump_label_lock(void)
23{
24 mutex_lock(&jump_label_mutex);
25}
26
27void jump_label_unlock(void)
28{
29 mutex_unlock(&jump_label_mutex);
30}
31
32static int jump_label_cmp(const void *a, const void *b)
33{
34 const struct jump_entry *jea = a;
35 const struct jump_entry *jeb = b;
36
37 if (jea->key < jeb->key)
38 return -1;
39
40 if (jea->key > jeb->key)
41 return 1;
42
43 return 0;
44}
45
46static void
47jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
48{
49 unsigned long size;
50
51 size = (((unsigned long)stop - (unsigned long)start)
52 / sizeof(struct jump_entry));
53 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
54}
55
56static void jump_label_update(struct static_key *key, int enable);
57
58void static_key_slow_inc(struct static_key *key)
59{
60 if (atomic_inc_not_zero(&key->enabled))
61 return;
62
63 jump_label_lock();
64 if (atomic_read(&key->enabled) == 0) {
65 if (!jump_label_get_branch_default(key))
66 jump_label_update(key, JUMP_LABEL_ENABLE);
67 else
68 jump_label_update(key, JUMP_LABEL_DISABLE);
69 }
70 atomic_inc(&key->enabled);
71 jump_label_unlock();
72}
73EXPORT_SYMBOL_GPL(static_key_slow_inc);
74
75static void __static_key_slow_dec(struct static_key *key,
76 unsigned long rate_limit, struct delayed_work *work)
77{
78 if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
79 WARN(atomic_read(&key->enabled) < 0,
80 "jump label: negative count!\n");
81 return;
82 }
83
84 if (rate_limit) {
85 atomic_inc(&key->enabled);
86 schedule_delayed_work(work, rate_limit);
87 } else {
88 if (!jump_label_get_branch_default(key))
89 jump_label_update(key, JUMP_LABEL_DISABLE);
90 else
91 jump_label_update(key, JUMP_LABEL_ENABLE);
92 }
93 jump_label_unlock();
94}
95
96static void jump_label_update_timeout(struct work_struct *work)
97{
98 struct static_key_deferred *key =
99 container_of(work, struct static_key_deferred, work.work);
100 __static_key_slow_dec(&key->key, 0, NULL);
101}
102
103void static_key_slow_dec(struct static_key *key)
104{
105 __static_key_slow_dec(key, 0, NULL);
106}
107EXPORT_SYMBOL_GPL(static_key_slow_dec);
108
109void static_key_slow_dec_deferred(struct static_key_deferred *key)
110{
111 __static_key_slow_dec(&key->key, key->timeout, &key->work);
112}
113EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
114
115void jump_label_rate_limit(struct static_key_deferred *key,
116 unsigned long rl)
117{
118 key->timeout = rl;
119 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
120}
121
122static int addr_conflict(struct jump_entry *entry, void *start, void *end)
123{
124 if (entry->code <= (unsigned long)end &&
125 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
126 return 1;
127
128 return 0;
129}
130
131static int __jump_label_text_reserved(struct jump_entry *iter_start,
132 struct jump_entry *iter_stop, void *start, void *end)
133{
134 struct jump_entry *iter;
135
136 iter = iter_start;
137 while (iter < iter_stop) {
138 if (addr_conflict(iter, start, end))
139 return 1;
140 iter++;
141 }
142
143 return 0;
144}
145
146/*
147 * Update code which is definitely not currently executing.
148 * Architectures which need heavyweight synchronization to modify
149 * running code can override this to make the non-live update case
150 * cheaper.
151 */
152void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
153 enum jump_label_type type)
154{
155 arch_jump_label_transform(entry, type);
156}
157
158static void __jump_label_update(struct static_key *key,
159 struct jump_entry *entry,
160 struct jump_entry *stop, int enable)
161{
162 for (; (entry < stop) &&
163 (entry->key == (jump_label_t)(unsigned long)key);
164 entry++) {
165 /*
166 * entry->code set to 0 invalidates module init text sections
167 * kernel_text_address() verifies we are not in core kernel
168 * init code, see jump_label_invalidate_module_init().
169 */
170 if (entry->code && kernel_text_address(entry->code))
171 arch_jump_label_transform(entry, enable);
172 }
173}
174
175static enum jump_label_type jump_label_type(struct static_key *key)
176{
177 bool true_branch = jump_label_get_branch_default(key);
178 bool state = static_key_enabled(key);
179
180 if ((!true_branch && state) || (true_branch && !state))
181 return JUMP_LABEL_ENABLE;
182
183 return JUMP_LABEL_DISABLE;
184}
185
186void __init jump_label_init(void)
187{
188 struct jump_entry *iter_start = __start___jump_table;
189 struct jump_entry *iter_stop = __stop___jump_table;
190 struct static_key *key = NULL;
191 struct jump_entry *iter;
192
193 jump_label_lock();
194 jump_label_sort_entries(iter_start, iter_stop);
195
196 for (iter = iter_start; iter < iter_stop; iter++) {
197 struct static_key *iterk;
198
199 iterk = (struct static_key *)(unsigned long)iter->key;
200 arch_jump_label_transform_static(iter, jump_label_type(iterk));
201 if (iterk == key)
202 continue;
203
204 key = iterk;
205 /*
206 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
207 */
208 *((unsigned long *)&key->entries) += (unsigned long)iter;
209#ifdef CONFIG_MODULES
210 key->next = NULL;
211#endif
212 }
213 jump_label_unlock();
214}
215
216#ifdef CONFIG_MODULES
217
218struct static_key_mod {
219 struct static_key_mod *next;
220 struct jump_entry *entries;
221 struct module *mod;
222};
223
224static int __jump_label_mod_text_reserved(void *start, void *end)
225{
226 struct module *mod;
227
228 mod = __module_text_address((unsigned long)start);
229 if (!mod)
230 return 0;
231
232 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
233
234 return __jump_label_text_reserved(mod->jump_entries,
235 mod->jump_entries + mod->num_jump_entries,
236 start, end);
237}
238
239static void __jump_label_mod_update(struct static_key *key, int enable)
240{
241 struct static_key_mod *mod = key->next;
242
243 while (mod) {
244 struct module *m = mod->mod;
245
246 __jump_label_update(key, mod->entries,
247 m->jump_entries + m->num_jump_entries,
248 enable);
249 mod = mod->next;
250 }
251}
252
253/***
254 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
255 * @mod: module to patch
256 *
257 * Allow for run-time selection of the optimal nops. Before the module
258 * loads patch these with arch_get_jump_label_nop(), which is specified by
259 * the arch specific jump label code.
260 */
261void jump_label_apply_nops(struct module *mod)
262{
263 struct jump_entry *iter_start = mod->jump_entries;
264 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
265 struct jump_entry *iter;
266
267 /* if the module doesn't have jump label entries, just return */
268 if (iter_start == iter_stop)
269 return;
270
271 for (iter = iter_start; iter < iter_stop; iter++) {
272 arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
273 }
274}
275
276static int jump_label_add_module(struct module *mod)
277{
278 struct jump_entry *iter_start = mod->jump_entries;
279 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
280 struct jump_entry *iter;
281 struct static_key *key = NULL;
282 struct static_key_mod *jlm;
283
284 /* if the module doesn't have jump label entries, just return */
285 if (iter_start == iter_stop)
286 return 0;
287
288 jump_label_sort_entries(iter_start, iter_stop);
289
290 for (iter = iter_start; iter < iter_stop; iter++) {
291 struct static_key *iterk;
292
293 iterk = (struct static_key *)(unsigned long)iter->key;
294 if (iterk == key)
295 continue;
296
297 key = iterk;
298 if (__module_address(iter->key) == mod) {
299 /*
300 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
301 */
302 *((unsigned long *)&key->entries) += (unsigned long)iter;
303 key->next = NULL;
304 continue;
305 }
306 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
307 if (!jlm)
308 return -ENOMEM;
309 jlm->mod = mod;
310 jlm->entries = iter;
311 jlm->next = key->next;
312 key->next = jlm;
313
314 if (jump_label_type(key) == JUMP_LABEL_ENABLE)
315 __jump_label_update(key, iter, iter_stop, JUMP_LABEL_ENABLE);
316 }
317
318 return 0;
319}
320
321static void jump_label_del_module(struct module *mod)
322{
323 struct jump_entry *iter_start = mod->jump_entries;
324 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
325 struct jump_entry *iter;
326 struct static_key *key = NULL;
327 struct static_key_mod *jlm, **prev;
328
329 for (iter = iter_start; iter < iter_stop; iter++) {
330 if (iter->key == (jump_label_t)(unsigned long)key)
331 continue;
332
333 key = (struct static_key *)(unsigned long)iter->key;
334
335 if (__module_address(iter->key) == mod)
336 continue;
337
338 prev = &key->next;
339 jlm = key->next;
340
341 while (jlm && jlm->mod != mod) {
342 prev = &jlm->next;
343 jlm = jlm->next;
344 }
345
346 if (jlm) {
347 *prev = jlm->next;
348 kfree(jlm);
349 }
350 }
351}
352
353static void jump_label_invalidate_module_init(struct module *mod)
354{
355 struct jump_entry *iter_start = mod->jump_entries;
356 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
357 struct jump_entry *iter;
358
359 for (iter = iter_start; iter < iter_stop; iter++) {
360 if (within_module_init(iter->code, mod))
361 iter->code = 0;
362 }
363}
364
365static int
366jump_label_module_notify(struct notifier_block *self, unsigned long val,
367 void *data)
368{
369 struct module *mod = data;
370 int ret = 0;
371
372 switch (val) {
373 case MODULE_STATE_COMING:
374 jump_label_lock();
375 ret = jump_label_add_module(mod);
376 if (ret)
377 jump_label_del_module(mod);
378 jump_label_unlock();
379 break;
380 case MODULE_STATE_GOING:
381 jump_label_lock();
382 jump_label_del_module(mod);
383 jump_label_unlock();
384 break;
385 case MODULE_STATE_LIVE:
386 jump_label_lock();
387 jump_label_invalidate_module_init(mod);
388 jump_label_unlock();
389 break;
390 }
391
392 return notifier_from_errno(ret);
393}
394
395struct notifier_block jump_label_module_nb = {
396 .notifier_call = jump_label_module_notify,
397 .priority = 1, /* higher than tracepoints */
398};
399
400static __init int jump_label_init_module(void)
401{
402 return register_module_notifier(&jump_label_module_nb);
403}
404early_initcall(jump_label_init_module);
405
406#endif /* CONFIG_MODULES */
407
408/***
409 * jump_label_text_reserved - check if addr range is reserved
410 * @start: start text addr
411 * @end: end text addr
412 *
413 * checks if the text addr located between @start and @end
414 * overlaps with any of the jump label patch addresses. Code
415 * that wants to modify kernel text should first verify that
416 * it does not overlap with any of the jump label addresses.
417 * Caller must hold jump_label_mutex.
418 *
419 * returns 1 if there is an overlap, 0 otherwise
420 */
421int jump_label_text_reserved(void *start, void *end)
422{
423 int ret = __jump_label_text_reserved(__start___jump_table,
424 __stop___jump_table, start, end);
425
426 if (ret)
427 return ret;
428
429#ifdef CONFIG_MODULES
430 ret = __jump_label_mod_text_reserved(start, end);
431#endif
432 return ret;
433}
434
435static void jump_label_update(struct static_key *key, int enable)
436{
437 struct jump_entry *stop = __stop___jump_table;
438 struct jump_entry *entry = jump_label_get_entries(key);
439
440#ifdef CONFIG_MODULES
441 struct module *mod = __module_address((unsigned long)key);
442
443 __jump_label_mod_update(key, enable);
444
445 if (mod)
446 stop = mod->jump_entries + mod->num_jump_entries;
447#endif
448 /* if there are no users, entry can be NULL */
449 if (entry)
450 __jump_label_update(key, entry, stop, enable);
451}
452
453#endif