blob: df3008419a1d0a34229580d86a2aec2f0e305d2a [file] [log] [blame]
Thomas Gleixner457c8992019-05-19 13:08:55 +01001// SPDX-License-Identifier: GPL-2.0-only
Jason Baronbf5438fc2010-09-17 11:09:00 -04002/*
3 * jump label support
4 *
5 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
Peter Zijlstra90eec102015-11-16 11:08:45 +01006 * Copyright (C) 2011 Peter Zijlstra
Jason Baronbf5438fc2010-09-17 11:09:00 -04007 *
8 */
Jason Baronbf5438fc2010-09-17 11:09:00 -04009#include <linux/memory.h>
10#include <linux/uaccess.h>
11#include <linux/module.h>
12#include <linux/list.h>
Jason Baronbf5438fc2010-09-17 11:09:00 -040013#include <linux/slab.h>
14#include <linux/sort.h>
15#include <linux/err.h>
Ingo Molnarc5905af2012-02-24 08:31:31 +010016#include <linux/static_key.h>
Andrew Jones851cf6e2013-08-09 19:51:57 +053017#include <linux/jump_label_ratelimit.h>
Jason Baron1f69bf92016-08-03 13:46:36 -070018#include <linux/bug.h>
Thomas Gleixnerf2545b2d2017-05-24 10:15:35 +020019#include <linux/cpu.h>
Josh Poimboeuf578ae442018-03-19 13:18:57 -050020#include <asm/sections.h>
Jason Baronbf5438fc2010-09-17 11:09:00 -040021
Jason Baronbf5438fc2010-09-17 11:09:00 -040022/* mutex to protect coming/going of the the jump_label table */
23static DEFINE_MUTEX(jump_label_mutex);
24
Jason Baron91bad2f2010-10-01 17:23:48 -040025void jump_label_lock(void)
26{
27 mutex_lock(&jump_label_mutex);
28}
29
30void jump_label_unlock(void)
31{
32 mutex_unlock(&jump_label_mutex);
33}
34
Jason Baronbf5438fc2010-09-17 11:09:00 -040035static int jump_label_cmp(const void *a, const void *b)
36{
37 const struct jump_entry *jea = a;
38 const struct jump_entry *jeb = b;
39
Daniel Bristot de Oliveira0f133022019-06-12 11:57:28 +020040 /*
41 * Entrires are sorted by key.
42 */
Ard Biesheuvel9ae033a2018-09-18 23:51:36 -070043 if (jump_entry_key(jea) < jump_entry_key(jeb))
Jason Baronbf5438fc2010-09-17 11:09:00 -040044 return -1;
45
Ard Biesheuvel9ae033a2018-09-18 23:51:36 -070046 if (jump_entry_key(jea) > jump_entry_key(jeb))
Jason Baronbf5438fc2010-09-17 11:09:00 -040047 return 1;
48
Daniel Bristot de Oliveira0f133022019-06-12 11:57:28 +020049 /*
50 * In the batching mode, entries should also be sorted by the code
51 * inside the already sorted list of entries, enabling a bsearch in
52 * the vector.
53 */
54 if (jump_entry_code(jea) < jump_entry_code(jeb))
55 return -1;
56
57 if (jump_entry_code(jea) > jump_entry_code(jeb))
58 return 1;
59
Jason Baronbf5438fc2010-09-17 11:09:00 -040060 return 0;
61}
62
Ard Biesheuvel50ff18a2018-09-18 23:51:37 -070063static void jump_label_swap(void *a, void *b, int size)
64{
65 long delta = (unsigned long)a - (unsigned long)b;
66 struct jump_entry *jea = a;
67 struct jump_entry *jeb = b;
68 struct jump_entry tmp = *jea;
69
70 jea->code = jeb->code - delta;
71 jea->target = jeb->target - delta;
72 jea->key = jeb->key - delta;
73
74 jeb->code = tmp.code + delta;
75 jeb->target = tmp.target + delta;
76 jeb->key = tmp.key + delta;
77}
78
Jason Baronbf5438fc2010-09-17 11:09:00 -040079static void
Jason Barond430d3d2011-03-16 17:29:47 -040080jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
Jason Baronbf5438fc2010-09-17 11:09:00 -040081{
82 unsigned long size;
Ard Biesheuvel50ff18a2018-09-18 23:51:37 -070083 void *swapfn = NULL;
84
85 if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE))
86 swapfn = jump_label_swap;
Jason Baronbf5438fc2010-09-17 11:09:00 -040087
88 size = (((unsigned long)stop - (unsigned long)start)
89 / sizeof(struct jump_entry));
Ard Biesheuvel50ff18a2018-09-18 23:51:37 -070090 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn);
Jason Baronbf5438fc2010-09-17 11:09:00 -040091}
92
Peter Zijlstra706249c2015-07-24 15:06:37 +020093static void jump_label_update(struct static_key *key);
Peter Zijlstraa1efb012015-07-24 14:55:40 +020094
Jason Baron1f69bf92016-08-03 13:46:36 -070095/*
Masahiro Yamadae9666d12018-12-31 00:14:15 +090096 * There are similar definitions for the !CONFIG_JUMP_LABEL case in jump_label.h.
Jason Baron1f69bf92016-08-03 13:46:36 -070097 * The use of 'atomic_read()' requires atomic.h and its problematic for some
98 * kernel headers such as kernel.h and others. Since static_key_count() is not
Masahiro Yamadae9666d12018-12-31 00:14:15 +090099 * used in the branch statements as it is for the !CONFIG_JUMP_LABEL case its ok
Jason Baron1f69bf92016-08-03 13:46:36 -0700100 * to have it be a function here. Similarly, for 'static_key_enable()' and
101 * 'static_key_disable()', which require bug.h. This should allow jump_label.h
Masahiro Yamadae9666d12018-12-31 00:14:15 +0900102 * to be included from most/all places for CONFIG_JUMP_LABEL.
Jason Baron1f69bf92016-08-03 13:46:36 -0700103 */
104int static_key_count(struct static_key *key)
105{
106 /*
107 * -1 means the first static_key_slow_inc() is in progress.
108 * static_key_enabled() must return true, so return 1 here.
109 */
110 int n = atomic_read(&key->enabled);
111
112 return n >= 0 ? n : 1;
113}
114EXPORT_SYMBOL_GPL(static_key_count);
115
Peter Zijlstrace48c1462018-01-22 22:53:28 +0100116void static_key_slow_inc_cpuslocked(struct static_key *key)
Jason Baronbf5438fc2010-09-17 11:09:00 -0400117{
Paolo Bonzini4c5ea0a2016-06-21 18:52:17 +0200118 int v, v1;
119
Borislav Petkov5cdda512017-10-18 17:24:28 +0200120 STATIC_KEY_CHECK_USE(key);
Peter Zijlstracb538262018-07-31 14:35:32 +0200121 lockdep_assert_cpus_held();
Paolo Bonzini4c5ea0a2016-06-21 18:52:17 +0200122
123 /*
124 * Careful if we get concurrent static_key_slow_inc() calls;
125 * later calls must wait for the first one to _finish_ the
126 * jump_label_update() process. At the same time, however,
127 * the jump_label_update() call below wants to see
128 * static_key_enabled(&key) for jumps to be updated properly.
129 *
130 * So give a special meaning to negative key->enabled: it sends
131 * static_key_slow_inc() down the slow path, and it is non-zero
132 * so it counts as "enabled" in jump_label_update(). Note that
133 * atomic_inc_unless_negative() checks >= 0, so roll our own.
134 */
135 for (v = atomic_read(&key->enabled); v > 0; v = v1) {
136 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
Marc Zyngier8b7b4122017-08-01 09:02:55 +0100137 if (likely(v1 == v))
Paolo Bonzini4c5ea0a2016-06-21 18:52:17 +0200138 return;
139 }
Jason Baronbf5438fc2010-09-17 11:09:00 -0400140
Jason Baron91bad2f2010-10-01 17:23:48 -0400141 jump_label_lock();
Paolo Bonzini4c5ea0a2016-06-21 18:52:17 +0200142 if (atomic_read(&key->enabled) == 0) {
143 atomic_set(&key->enabled, -1);
Peter Zijlstra706249c2015-07-24 15:06:37 +0200144 jump_label_update(key);
Peter Zijlstrad0646a62017-08-01 23:58:50 +0200145 /*
146 * Ensure that if the above cmpxchg loop observes our positive
147 * value, it must also observe all the text changes.
148 */
149 atomic_set_release(&key->enabled, 1);
Paolo Bonzini4c5ea0a2016-06-21 18:52:17 +0200150 } else {
151 atomic_inc(&key->enabled);
152 }
Jason Barond430d3d2011-03-16 17:29:47 -0400153 jump_label_unlock();
Marc Zyngier8b7b4122017-08-01 09:02:55 +0100154}
155
156void static_key_slow_inc(struct static_key *key)
157{
158 cpus_read_lock();
159 static_key_slow_inc_cpuslocked(key);
Thomas Gleixnerf2545b2d2017-05-24 10:15:35 +0200160 cpus_read_unlock();
Jason Barond430d3d2011-03-16 17:29:47 -0400161}
Ingo Molnarc5905af2012-02-24 08:31:31 +0100162EXPORT_SYMBOL_GPL(static_key_slow_inc);
Jason Barond430d3d2011-03-16 17:29:47 -0400163
Marc Zyngier5a405272017-08-01 09:02:56 +0100164void static_key_enable_cpuslocked(struct static_key *key)
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200165{
Borislav Petkov5cdda512017-10-18 17:24:28 +0200166 STATIC_KEY_CHECK_USE(key);
Peter Zijlstracb538262018-07-31 14:35:32 +0200167 lockdep_assert_cpus_held();
Marc Zyngier5a405272017-08-01 09:02:56 +0100168
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200169 if (atomic_read(&key->enabled) > 0) {
170 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
171 return;
172 }
173
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200174 jump_label_lock();
175 if (atomic_read(&key->enabled) == 0) {
176 atomic_set(&key->enabled, -1);
177 jump_label_update(key);
Peter Zijlstrad0646a62017-08-01 23:58:50 +0200178 /*
179 * See static_key_slow_inc().
180 */
181 atomic_set_release(&key->enabled, 1);
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200182 }
183 jump_label_unlock();
Marc Zyngier5a405272017-08-01 09:02:56 +0100184}
185EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
186
187void static_key_enable(struct static_key *key)
188{
189 cpus_read_lock();
190 static_key_enable_cpuslocked(key);
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200191 cpus_read_unlock();
192}
193EXPORT_SYMBOL_GPL(static_key_enable);
194
Marc Zyngier5a405272017-08-01 09:02:56 +0100195void static_key_disable_cpuslocked(struct static_key *key)
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200196{
Borislav Petkov5cdda512017-10-18 17:24:28 +0200197 STATIC_KEY_CHECK_USE(key);
Peter Zijlstracb538262018-07-31 14:35:32 +0200198 lockdep_assert_cpus_held();
Marc Zyngier5a405272017-08-01 09:02:56 +0100199
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200200 if (atomic_read(&key->enabled) != 1) {
201 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
202 return;
203 }
204
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200205 jump_label_lock();
206 if (atomic_cmpxchg(&key->enabled, 1, 0))
207 jump_label_update(key);
208 jump_label_unlock();
Marc Zyngier5a405272017-08-01 09:02:56 +0100209}
210EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
211
212void static_key_disable(struct static_key *key)
213{
214 cpus_read_lock();
215 static_key_disable_cpuslocked(key);
Paolo Bonzini1dbb6702017-08-01 17:24:04 +0200216 cpus_read_unlock();
217}
218EXPORT_SYMBOL_GPL(static_key_disable);
219
Jakub Kicinskib92e7932019-03-29 17:08:53 -0700220static bool static_key_slow_try_dec(struct static_key *key)
Jason Barond430d3d2011-03-16 17:29:47 -0400221{
Peter Zijlstraa1247d02019-03-19 13:18:56 +0100222 int val;
223
Jakub Kicinskib92e7932019-03-29 17:08:53 -0700224 val = atomic_fetch_add_unless(&key->enabled, -1, 1);
225 if (val == 1)
226 return false;
Peter Zijlstracb538262018-07-31 14:35:32 +0200227
Paolo Bonzini4c5ea0a2016-06-21 18:52:17 +0200228 /*
229 * The negative count check is valid even when a negative
230 * key->enabled is in use by static_key_slow_inc(); a
231 * __static_key_slow_dec() before the first static_key_slow_inc()
232 * returns is unbalanced, because all other static_key_slow_inc()
233 * instances block while the update is in progress.
234 */
Jakub Kicinskib92e7932019-03-29 17:08:53 -0700235 WARN(val < 0, "jump label: negative count!\n");
236 return true;
237}
238
Jakub Kicinski94b5f312019-03-29 17:08:54 -0700239static void __static_key_slow_dec_cpuslocked(struct static_key *key)
Jakub Kicinskib92e7932019-03-29 17:08:53 -0700240{
241 lockdep_assert_cpus_held();
242
243 if (static_key_slow_try_dec(key))
Jason Barond430d3d2011-03-16 17:29:47 -0400244 return;
245
Peter Zijlstraa1247d02019-03-19 13:18:56 +0100246 jump_label_lock();
Jakub Kicinski94b5f312019-03-29 17:08:54 -0700247 if (atomic_dec_and_test(&key->enabled))
248 jump_label_update(key);
Jason Baron91bad2f2010-10-01 17:23:48 -0400249 jump_label_unlock();
Marc Zyngier8b7b4122017-08-01 09:02:55 +0100250}
251
Jakub Kicinski94b5f312019-03-29 17:08:54 -0700252static void __static_key_slow_dec(struct static_key *key)
Marc Zyngier8b7b4122017-08-01 09:02:55 +0100253{
254 cpus_read_lock();
Jakub Kicinski94b5f312019-03-29 17:08:54 -0700255 __static_key_slow_dec_cpuslocked(key);
Thomas Gleixnerf2545b2d2017-05-24 10:15:35 +0200256 cpus_read_unlock();
Jason Baronbf5438fc2010-09-17 11:09:00 -0400257}
258
Jakub Kicinskiad282a82019-03-29 17:08:52 -0700259void jump_label_update_timeout(struct work_struct *work)
Gleb Natapovb2029522011-11-27 17:59:09 +0200260{
Ingo Molnarc5905af2012-02-24 08:31:31 +0100261 struct static_key_deferred *key =
262 container_of(work, struct static_key_deferred, work.work);
Jakub Kicinski94b5f312019-03-29 17:08:54 -0700263 __static_key_slow_dec(&key->key);
Gleb Natapovb2029522011-11-27 17:59:09 +0200264}
Jakub Kicinskiad282a82019-03-29 17:08:52 -0700265EXPORT_SYMBOL_GPL(jump_label_update_timeout);
Gleb Natapovb2029522011-11-27 17:59:09 +0200266
Ingo Molnarc5905af2012-02-24 08:31:31 +0100267void static_key_slow_dec(struct static_key *key)
Gleb Natapovb2029522011-11-27 17:59:09 +0200268{
Borislav Petkov5cdda512017-10-18 17:24:28 +0200269 STATIC_KEY_CHECK_USE(key);
Jakub Kicinski94b5f312019-03-29 17:08:54 -0700270 __static_key_slow_dec(key);
Gleb Natapovb2029522011-11-27 17:59:09 +0200271}
Ingo Molnarc5905af2012-02-24 08:31:31 +0100272EXPORT_SYMBOL_GPL(static_key_slow_dec);
Gleb Natapovb2029522011-11-27 17:59:09 +0200273
Peter Zijlstrace48c1462018-01-22 22:53:28 +0100274void static_key_slow_dec_cpuslocked(struct static_key *key)
275{
276 STATIC_KEY_CHECK_USE(key);
Jakub Kicinski94b5f312019-03-29 17:08:54 -0700277 __static_key_slow_dec_cpuslocked(key);
Peter Zijlstrace48c1462018-01-22 22:53:28 +0100278}
279
Jakub Kicinskiad282a82019-03-29 17:08:52 -0700280void __static_key_slow_dec_deferred(struct static_key *key,
281 struct delayed_work *work,
282 unsigned long timeout)
Gleb Natapovb2029522011-11-27 17:59:09 +0200283{
Borislav Petkov5cdda512017-10-18 17:24:28 +0200284 STATIC_KEY_CHECK_USE(key);
Jakub Kicinski94b5f312019-03-29 17:08:54 -0700285
286 if (static_key_slow_try_dec(key))
287 return;
288
289 schedule_delayed_work(work, timeout);
Gleb Natapovb2029522011-11-27 17:59:09 +0200290}
Jakub Kicinskiad282a82019-03-29 17:08:52 -0700291EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
Gleb Natapovb2029522011-11-27 17:59:09 +0200292
Jakub Kicinskiad282a82019-03-29 17:08:52 -0700293void __static_key_deferred_flush(void *key, struct delayed_work *work)
David Matlackb6416e62016-12-16 14:30:35 -0800294{
Borislav Petkov5cdda512017-10-18 17:24:28 +0200295 STATIC_KEY_CHECK_USE(key);
Jakub Kicinskiad282a82019-03-29 17:08:52 -0700296 flush_delayed_work(work);
David Matlackb6416e62016-12-16 14:30:35 -0800297}
Jakub Kicinskiad282a82019-03-29 17:08:52 -0700298EXPORT_SYMBOL_GPL(__static_key_deferred_flush);
David Matlackb6416e62016-12-16 14:30:35 -0800299
Ingo Molnarc5905af2012-02-24 08:31:31 +0100300void jump_label_rate_limit(struct static_key_deferred *key,
Gleb Natapovb2029522011-11-27 17:59:09 +0200301 unsigned long rl)
302{
Borislav Petkov5cdda512017-10-18 17:24:28 +0200303 STATIC_KEY_CHECK_USE(key);
Gleb Natapovb2029522011-11-27 17:59:09 +0200304 key->timeout = rl;
305 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
306}
Gleb Natapova181dc12012-08-05 15:58:29 +0300307EXPORT_SYMBOL_GPL(jump_label_rate_limit);
Gleb Natapovb2029522011-11-27 17:59:09 +0200308
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400309static int addr_conflict(struct jump_entry *entry, void *start, void *end)
310{
Ard Biesheuvel9ae033a2018-09-18 23:51:36 -0700311 if (jump_entry_code(entry) <= (unsigned long)end &&
312 jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400313 return 1;
314
315 return 0;
316}
317
Jason Barond430d3d2011-03-16 17:29:47 -0400318static int __jump_label_text_reserved(struct jump_entry *iter_start,
319 struct jump_entry *iter_stop, void *start, void *end)
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400320{
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400321 struct jump_entry *iter;
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400322
Jason Barond430d3d2011-03-16 17:29:47 -0400323 iter = iter_start;
324 while (iter < iter_stop) {
325 if (addr_conflict(iter, start, end))
326 return 1;
327 iter++;
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400328 }
Jason Barond430d3d2011-03-16 17:29:47 -0400329
330 return 0;
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400331}
332
Peter Zijlstra706249c2015-07-24 15:06:37 +0200333/*
Jeremy Fitzhardinge20284aa2011-10-03 11:01:46 -0700334 * Update code which is definitely not currently executing.
335 * Architectures which need heavyweight synchronization to modify
336 * running code can override this to make the non-live update case
337 * cheaper.
338 */
Peter Zijlstra9cdbe1c2011-12-06 17:27:29 +0100339void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
Jeremy Fitzhardinge20284aa2011-10-03 11:01:46 -0700340 enum jump_label_type type)
341{
Peter Zijlstra706249c2015-07-24 15:06:37 +0200342 arch_jump_label_transform(entry, type);
Jason Barond430d3d2011-03-16 17:29:47 -0400343}
344
Peter Zijlstraa1efb012015-07-24 14:55:40 +0200345static inline struct jump_entry *static_key_entries(struct static_key *key)
346{
Jason Baron3821fd32017-02-03 15:42:24 -0500347 WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
348 return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
Peter Zijlstraa1efb012015-07-24 14:55:40 +0200349}
350
Peter Zijlstra706249c2015-07-24 15:06:37 +0200351static inline bool static_key_type(struct static_key *key)
352{
Jason Baron3821fd32017-02-03 15:42:24 -0500353 return key->type & JUMP_TYPE_TRUE;
354}
355
356static inline bool static_key_linked(struct static_key *key)
357{
358 return key->type & JUMP_TYPE_LINKED;
359}
360
361static inline void static_key_clear_linked(struct static_key *key)
362{
363 key->type &= ~JUMP_TYPE_LINKED;
364}
365
366static inline void static_key_set_linked(struct static_key *key)
367{
368 key->type |= JUMP_TYPE_LINKED;
Peter Zijlstra706249c2015-07-24 15:06:37 +0200369}
370
Jason Baron3821fd32017-02-03 15:42:24 -0500371/***
372 * A 'struct static_key' uses a union such that it either points directly
373 * to a table of 'struct jump_entry' or to a linked list of modules which in
374 * turn point to 'struct jump_entry' tables.
375 *
376 * The two lower bits of the pointer are used to keep track of which pointer
377 * type is in use and to store the initial branch direction, we use an access
378 * function which preserves these bits.
379 */
380static void static_key_set_entries(struct static_key *key,
381 struct jump_entry *entries)
382{
383 unsigned long type;
384
385 WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
386 type = key->type & JUMP_TYPE_MASK;
387 key->entries = entries;
388 key->type |= type;
389}
390
Peter Zijlstra706249c2015-07-24 15:06:37 +0200391static enum jump_label_type jump_label_type(struct jump_entry *entry)
Ingo Molnarc5905af2012-02-24 08:31:31 +0100392{
Peter Zijlstra706249c2015-07-24 15:06:37 +0200393 struct static_key *key = jump_entry_key(entry);
Peter Zijlstraa1efb012015-07-24 14:55:40 +0200394 bool enabled = static_key_enabled(key);
Ard Biesheuvel9ae033a2018-09-18 23:51:36 -0700395 bool branch = jump_entry_is_branch(entry);
Ingo Molnarc5905af2012-02-24 08:31:31 +0100396
Peter Zijlstra11276d52015-07-24 15:09:55 +0200397 /* See the comment in linux/jump_label.h */
398 return enabled ^ branch;
Ingo Molnarc5905af2012-02-24 08:31:31 +0100399}
400
Daniel Bristot de Oliveirae1aacb32019-06-12 11:57:26 +0200401static bool jump_label_can_update(struct jump_entry *entry, bool init)
402{
403 /*
404 * Cannot update code that was in an init text area.
405 */
406 if (!init && jump_entry_is_init(entry))
407 return false;
408
409 if (!kernel_text_address(jump_entry_code(entry))) {
410 WARN_ONCE(1, "can't patch jump_label at %pS", (void *)jump_entry_code(entry));
411 return false;
412 }
413
414 return true;
415}
416
Daniel Bristot de Oliveirac2ba8a12019-06-12 11:57:30 +0200417#ifndef HAVE_JUMP_LABEL_BATCH
Peter Zijlstra706249c2015-07-24 15:06:37 +0200418static void __jump_label_update(struct static_key *key,
419 struct jump_entry *entry,
Ard Biesheuvel19483672018-09-18 23:51:42 -0700420 struct jump_entry *stop,
421 bool init)
Peter Zijlstra706249c2015-07-24 15:06:37 +0200422{
423 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
Daniel Bristot de Oliveirae1aacb32019-06-12 11:57:26 +0200424 if (jump_label_can_update(entry, init))
425 arch_jump_label_transform(entry, jump_label_type(entry));
Peter Zijlstra706249c2015-07-24 15:06:37 +0200426 }
427}
Daniel Bristot de Oliveirac2ba8a12019-06-12 11:57:30 +0200428#else
429static void __jump_label_update(struct static_key *key,
430 struct jump_entry *entry,
431 struct jump_entry *stop,
432 bool init)
433{
434 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
435
436 if (!jump_label_can_update(entry, init))
437 continue;
438
439 if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) {
440 /*
441 * Queue is full: Apply the current queue and try again.
442 */
443 arch_jump_label_transform_apply();
444 BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry)));
445 }
446 }
447 arch_jump_label_transform_apply();
448}
449#endif
Peter Zijlstra706249c2015-07-24 15:06:37 +0200450
Jeremy Fitzhardinge97ce2c82011-10-12 16:17:54 -0700451void __init jump_label_init(void)
Jason Barond430d3d2011-03-16 17:29:47 -0400452{
453 struct jump_entry *iter_start = __start___jump_table;
454 struct jump_entry *iter_stop = __stop___jump_table;
Ingo Molnarc5905af2012-02-24 08:31:31 +0100455 struct static_key *key = NULL;
Jason Barond430d3d2011-03-16 17:29:47 -0400456 struct jump_entry *iter;
457
Jason Baron1f69bf92016-08-03 13:46:36 -0700458 /*
459 * Since we are initializing the static_key.enabled field with
460 * with the 'raw' int values (to avoid pulling in atomic.h) in
461 * jump_label.h, let's make sure that is safe. There are only two
462 * cases to check since we initialize to 0 or 1.
463 */
464 BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
465 BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
466
Kevin Haoe3f91082016-07-23 14:42:37 +0530467 if (static_key_initialized)
468 return;
469
Thomas Gleixnerf2545b2d2017-05-24 10:15:35 +0200470 cpus_read_lock();
Jason Barond430d3d2011-03-16 17:29:47 -0400471 jump_label_lock();
472 jump_label_sort_entries(iter_start, iter_stop);
473
474 for (iter = iter_start; iter < iter_stop; iter++) {
Ingo Molnarc5905af2012-02-24 08:31:31 +0100475 struct static_key *iterk;
Jeremy Fitzhardinge37348802011-09-29 11:10:05 -0700476
Peter Zijlstra11276d52015-07-24 15:09:55 +0200477 /* rewrite NOPs */
478 if (jump_label_type(iter) == JUMP_LABEL_NOP)
479 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
480
Ard Biesheuvel19483672018-09-18 23:51:42 -0700481 if (init_section_contains((void *)jump_entry_code(iter), 1))
482 jump_entry_set_init(iter);
483
Peter Zijlstra7dcfd912015-07-24 15:02:27 +0200484 iterk = jump_entry_key(iter);
Jeremy Fitzhardinge37348802011-09-29 11:10:05 -0700485 if (iterk == key)
Jason Barond430d3d2011-03-16 17:29:47 -0400486 continue;
487
Jeremy Fitzhardinge37348802011-09-29 11:10:05 -0700488 key = iterk;
Jason Baron3821fd32017-02-03 15:42:24 -0500489 static_key_set_entries(key, iter);
Jason Barond430d3d2011-03-16 17:29:47 -0400490 }
Hannes Frederic Sowac4b2c0c2013-10-19 21:48:53 +0200491 static_key_initialized = true;
Jason Barond430d3d2011-03-16 17:29:47 -0400492 jump_label_unlock();
Thomas Gleixnerf2545b2d2017-05-24 10:15:35 +0200493 cpus_read_unlock();
Jason Barond430d3d2011-03-16 17:29:47 -0400494}
Jason Barond430d3d2011-03-16 17:29:47 -0400495
496#ifdef CONFIG_MODULES
497
Peter Zijlstra11276d52015-07-24 15:09:55 +0200498static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
499{
500 struct static_key *key = jump_entry_key(entry);
501 bool type = static_key_type(key);
Ard Biesheuvel9ae033a2018-09-18 23:51:36 -0700502 bool branch = jump_entry_is_branch(entry);
Peter Zijlstra11276d52015-07-24 15:09:55 +0200503
504 /* See the comment in linux/jump_label.h */
505 return type ^ branch;
506}
507
Ingo Molnarc5905af2012-02-24 08:31:31 +0100508struct static_key_mod {
509 struct static_key_mod *next;
Jason Barond430d3d2011-03-16 17:29:47 -0400510 struct jump_entry *entries;
511 struct module *mod;
512};
513
Jason Baron3821fd32017-02-03 15:42:24 -0500514static inline struct static_key_mod *static_key_mod(struct static_key *key)
515{
Borislav Petkov34e12b82018-09-09 13:42:52 +0200516 WARN_ON_ONCE(!static_key_linked(key));
Jason Baron3821fd32017-02-03 15:42:24 -0500517 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
518}
519
520/***
521 * key->type and key->next are the same via union.
522 * This sets key->next and preserves the type bits.
523 *
524 * See additional comments above static_key_set_entries().
525 */
526static void static_key_set_mod(struct static_key *key,
527 struct static_key_mod *mod)
528{
529 unsigned long type;
530
531 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
532 type = key->type & JUMP_TYPE_MASK;
533 key->next = mod;
534 key->type |= type;
535}
536
Jason Barond430d3d2011-03-16 17:29:47 -0400537static int __jump_label_mod_text_reserved(void *start, void *end)
538{
539 struct module *mod;
540
Rusty Russellbdc9f372016-07-27 12:17:35 +0930541 preempt_disable();
Jason Barond430d3d2011-03-16 17:29:47 -0400542 mod = __module_text_address((unsigned long)start);
Rusty Russellbdc9f372016-07-27 12:17:35 +0930543 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
544 preempt_enable();
545
Jason Barond430d3d2011-03-16 17:29:47 -0400546 if (!mod)
547 return 0;
548
Jason Barond430d3d2011-03-16 17:29:47 -0400549
550 return __jump_label_text_reserved(mod->jump_entries,
551 mod->jump_entries + mod->num_jump_entries,
552 start, end);
553}
554
Peter Zijlstra706249c2015-07-24 15:06:37 +0200555static void __jump_label_mod_update(struct static_key *key)
Jason Barond430d3d2011-03-16 17:29:47 -0400556{
Peter Zijlstra706249c2015-07-24 15:06:37 +0200557 struct static_key_mod *mod;
Jason Barond430d3d2011-03-16 17:29:47 -0400558
Jason Baron3821fd32017-02-03 15:42:24 -0500559 for (mod = static_key_mod(key); mod; mod = mod->next) {
560 struct jump_entry *stop;
561 struct module *m;
Jiri Olsa7cbc5b82011-05-10 12:43:46 +0200562
Jason Baron3821fd32017-02-03 15:42:24 -0500563 /*
564 * NULL if the static_key is defined in a module
565 * that does not use it
566 */
567 if (!mod->entries)
568 continue;
569
570 m = mod->mod;
571 if (!m)
572 stop = __stop___jump_table;
573 else
574 stop = m->jump_entries + m->num_jump_entries;
Ard Biesheuvel19483672018-09-18 23:51:42 -0700575 __jump_label_update(key, mod->entries, stop,
Ard Biesheuvel77ac1c02018-10-01 10:13:24 +0200576 m && m->state == MODULE_STATE_COMING);
Jason Barond430d3d2011-03-16 17:29:47 -0400577 }
578}
579
580/***
581 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
582 * @mod: module to patch
583 *
584 * Allow for run-time selection of the optimal nops. Before the module
585 * loads patch these with arch_get_jump_label_nop(), which is specified by
586 * the arch specific jump label code.
587 */
588void jump_label_apply_nops(struct module *mod)
589{
590 struct jump_entry *iter_start = mod->jump_entries;
591 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
592 struct jump_entry *iter;
593
594 /* if the module doesn't have jump label entries, just return */
595 if (iter_start == iter_stop)
596 return;
597
Peter Zijlstra11276d52015-07-24 15:09:55 +0200598 for (iter = iter_start; iter < iter_stop; iter++) {
599 /* Only write NOPs for arch_branch_static(). */
600 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
601 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
602 }
Jason Barond430d3d2011-03-16 17:29:47 -0400603}
604
605static int jump_label_add_module(struct module *mod)
606{
607 struct jump_entry *iter_start = mod->jump_entries;
608 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
609 struct jump_entry *iter;
Ingo Molnarc5905af2012-02-24 08:31:31 +0100610 struct static_key *key = NULL;
Jason Baron3821fd32017-02-03 15:42:24 -0500611 struct static_key_mod *jlm, *jlm2;
Jason Barond430d3d2011-03-16 17:29:47 -0400612
613 /* if the module doesn't have jump label entries, just return */
614 if (iter_start == iter_stop)
615 return 0;
616
617 jump_label_sort_entries(iter_start, iter_stop);
618
619 for (iter = iter_start; iter < iter_stop; iter++) {
Ingo Molnarc5905af2012-02-24 08:31:31 +0100620 struct static_key *iterk;
621
Ard Biesheuvel19483672018-09-18 23:51:42 -0700622 if (within_module_init(jump_entry_code(iter), mod))
623 jump_entry_set_init(iter);
624
Peter Zijlstra7dcfd912015-07-24 15:02:27 +0200625 iterk = jump_entry_key(iter);
Ingo Molnarc5905af2012-02-24 08:31:31 +0100626 if (iterk == key)
Jason Barond430d3d2011-03-16 17:29:47 -0400627 continue;
628
Ingo Molnarc5905af2012-02-24 08:31:31 +0100629 key = iterk;
Ard Biesheuvel9ae033a2018-09-18 23:51:36 -0700630 if (within_module((unsigned long)key, mod)) {
Jason Baron3821fd32017-02-03 15:42:24 -0500631 static_key_set_entries(key, iter);
Jason Barond430d3d2011-03-16 17:29:47 -0400632 continue;
633 }
Ingo Molnarc5905af2012-02-24 08:31:31 +0100634 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
Jason Barond430d3d2011-03-16 17:29:47 -0400635 if (!jlm)
636 return -ENOMEM;
Jason Baron3821fd32017-02-03 15:42:24 -0500637 if (!static_key_linked(key)) {
638 jlm2 = kzalloc(sizeof(struct static_key_mod),
639 GFP_KERNEL);
640 if (!jlm2) {
641 kfree(jlm);
642 return -ENOMEM;
643 }
644 preempt_disable();
645 jlm2->mod = __module_address((unsigned long)key);
646 preempt_enable();
647 jlm2->entries = static_key_entries(key);
648 jlm2->next = NULL;
649 static_key_set_mod(key, jlm2);
650 static_key_set_linked(key);
651 }
Jason Barond430d3d2011-03-16 17:29:47 -0400652 jlm->mod = mod;
653 jlm->entries = iter;
Jason Baron3821fd32017-02-03 15:42:24 -0500654 jlm->next = static_key_mod(key);
655 static_key_set_mod(key, jlm);
656 static_key_set_linked(key);
Jason Barond430d3d2011-03-16 17:29:47 -0400657
Peter Zijlstra11276d52015-07-24 15:09:55 +0200658 /* Only update if we've changed from our initial state */
659 if (jump_label_type(iter) != jump_label_init_type(iter))
Ard Biesheuvel19483672018-09-18 23:51:42 -0700660 __jump_label_update(key, iter, iter_stop, true);
Jason Barond430d3d2011-03-16 17:29:47 -0400661 }
662
663 return 0;
664}
665
666static void jump_label_del_module(struct module *mod)
667{
668 struct jump_entry *iter_start = mod->jump_entries;
669 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
670 struct jump_entry *iter;
Ingo Molnarc5905af2012-02-24 08:31:31 +0100671 struct static_key *key = NULL;
672 struct static_key_mod *jlm, **prev;
Jason Barond430d3d2011-03-16 17:29:47 -0400673
674 for (iter = iter_start; iter < iter_stop; iter++) {
Peter Zijlstra7dcfd912015-07-24 15:02:27 +0200675 if (jump_entry_key(iter) == key)
Jason Barond430d3d2011-03-16 17:29:47 -0400676 continue;
677
Peter Zijlstra7dcfd912015-07-24 15:02:27 +0200678 key = jump_entry_key(iter);
Jason Barond430d3d2011-03-16 17:29:47 -0400679
Ard Biesheuvel9ae033a2018-09-18 23:51:36 -0700680 if (within_module((unsigned long)key, mod))
Jason Barond430d3d2011-03-16 17:29:47 -0400681 continue;
682
Jason Baron3821fd32017-02-03 15:42:24 -0500683 /* No memory during module load */
684 if (WARN_ON(!static_key_linked(key)))
685 continue;
686
Jason Barond430d3d2011-03-16 17:29:47 -0400687 prev = &key->next;
Jason Baron3821fd32017-02-03 15:42:24 -0500688 jlm = static_key_mod(key);
Jason Barond430d3d2011-03-16 17:29:47 -0400689
690 while (jlm && jlm->mod != mod) {
691 prev = &jlm->next;
692 jlm = jlm->next;
693 }
694
Jason Baron3821fd32017-02-03 15:42:24 -0500695 /* No memory during module load */
696 if (WARN_ON(!jlm))
697 continue;
698
699 if (prev == &key->next)
700 static_key_set_mod(key, jlm->next);
701 else
Jason Barond430d3d2011-03-16 17:29:47 -0400702 *prev = jlm->next;
Jason Baron3821fd32017-02-03 15:42:24 -0500703
704 kfree(jlm);
705
706 jlm = static_key_mod(key);
707 /* if only one etry is left, fold it back into the static_key */
708 if (jlm->next == NULL) {
709 static_key_set_entries(key, jlm->entries);
710 static_key_clear_linked(key);
Jason Barond430d3d2011-03-16 17:29:47 -0400711 kfree(jlm);
712 }
713 }
714}
715
Jason Barond430d3d2011-03-16 17:29:47 -0400716static int
717jump_label_module_notify(struct notifier_block *self, unsigned long val,
718 void *data)
719{
720 struct module *mod = data;
721 int ret = 0;
722
Thomas Gleixnerf2545b2d2017-05-24 10:15:35 +0200723 cpus_read_lock();
724 jump_label_lock();
725
Jason Barond430d3d2011-03-16 17:29:47 -0400726 switch (val) {
727 case MODULE_STATE_COMING:
Jason Barond430d3d2011-03-16 17:29:47 -0400728 ret = jump_label_add_module(mod);
Jason Baron3821fd32017-02-03 15:42:24 -0500729 if (ret) {
Borislav Petkovda260fe2018-09-07 12:35:21 +0200730 WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
Jason Barond430d3d2011-03-16 17:29:47 -0400731 jump_label_del_module(mod);
Jason Baron3821fd32017-02-03 15:42:24 -0500732 }
Jason Barond430d3d2011-03-16 17:29:47 -0400733 break;
734 case MODULE_STATE_GOING:
Jason Barond430d3d2011-03-16 17:29:47 -0400735 jump_label_del_module(mod);
Jason Barond430d3d2011-03-16 17:29:47 -0400736 break;
Jason Barond430d3d2011-03-16 17:29:47 -0400737 }
738
Thomas Gleixnerf2545b2d2017-05-24 10:15:35 +0200739 jump_label_unlock();
740 cpus_read_unlock();
741
Jason Barond430d3d2011-03-16 17:29:47 -0400742 return notifier_from_errno(ret);
743}
744
Wei Yongjun885885f2016-06-17 17:19:40 +0000745static struct notifier_block jump_label_module_nb = {
Jason Barond430d3d2011-03-16 17:29:47 -0400746 .notifier_call = jump_label_module_notify,
747 .priority = 1, /* higher than tracepoints */
748};
749
750static __init int jump_label_init_module(void)
751{
752 return register_module_notifier(&jump_label_module_nb);
753}
754early_initcall(jump_label_init_module);
755
756#endif /* CONFIG_MODULES */
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400757
758/***
759 * jump_label_text_reserved - check if addr range is reserved
760 * @start: start text addr
761 * @end: end text addr
762 *
763 * checks if the text addr located between @start and @end
764 * overlaps with any of the jump label patch addresses. Code
765 * that wants to modify kernel text should first verify that
766 * it does not overlap with any of the jump label addresses.
Jason Baron91bad2f2010-10-01 17:23:48 -0400767 * Caller must hold jump_label_mutex.
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400768 *
769 * returns 1 if there is an overlap, 0 otherwise
770 */
771int jump_label_text_reserved(void *start, void *end)
772{
Jason Barond430d3d2011-03-16 17:29:47 -0400773 int ret = __jump_label_text_reserved(__start___jump_table,
774 __stop___jump_table, start, end);
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400775
Jason Barond430d3d2011-03-16 17:29:47 -0400776 if (ret)
777 return ret;
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400778
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400779#ifdef CONFIG_MODULES
Jason Barond430d3d2011-03-16 17:29:47 -0400780 ret = __jump_label_mod_text_reserved(start, end);
Jason Baron4c3ef6d2010-09-17 11:09:08 -0400781#endif
Jason Baronbf5438fc2010-09-17 11:09:00 -0400782 return ret;
783}
Jason Barond430d3d2011-03-16 17:29:47 -0400784
Peter Zijlstra706249c2015-07-24 15:06:37 +0200785static void jump_label_update(struct static_key *key)
Jason Barond430d3d2011-03-16 17:29:47 -0400786{
Ingo Molnarc5905af2012-02-24 08:31:31 +0100787 struct jump_entry *stop = __stop___jump_table;
Jason Baron3821fd32017-02-03 15:42:24 -0500788 struct jump_entry *entry;
Jason Baronbf5438fc2010-09-17 11:09:00 -0400789#ifdef CONFIG_MODULES
Peter Zijlstrabed831f2015-05-27 11:09:35 +0930790 struct module *mod;
Xiao Guangrong140fe3b2011-06-21 10:35:55 +0800791
Jason Baron3821fd32017-02-03 15:42:24 -0500792 if (static_key_linked(key)) {
793 __jump_label_mod_update(key);
794 return;
795 }
Xiao Guangrong140fe3b2011-06-21 10:35:55 +0800796
Peter Zijlstrabed831f2015-05-27 11:09:35 +0930797 preempt_disable();
798 mod = __module_address((unsigned long)key);
Xiao Guangrong140fe3b2011-06-21 10:35:55 +0800799 if (mod)
800 stop = mod->jump_entries + mod->num_jump_entries;
Peter Zijlstrabed831f2015-05-27 11:09:35 +0930801 preempt_enable();
Jason Barond430d3d2011-03-16 17:29:47 -0400802#endif
Jason Baron3821fd32017-02-03 15:42:24 -0500803 entry = static_key_entries(key);
Xiao Guangrong140fe3b2011-06-21 10:35:55 +0800804 /* if there are no users, entry can be NULL */
805 if (entry)
Ard Biesheuvel19483672018-09-18 23:51:42 -0700806 __jump_label_update(key, entry, stop,
807 system_state < SYSTEM_RUNNING);
Jason Baronbf5438fc2010-09-17 11:09:00 -0400808}
809
Peter Zijlstra1987c942015-07-27 18:32:09 +0200810#ifdef CONFIG_STATIC_KEYS_SELFTEST
811static DEFINE_STATIC_KEY_TRUE(sk_true);
812static DEFINE_STATIC_KEY_FALSE(sk_false);
813
814static __init int jump_label_test(void)
815{
816 int i;
817
818 for (i = 0; i < 2; i++) {
819 WARN_ON(static_key_enabled(&sk_true.key) != true);
820 WARN_ON(static_key_enabled(&sk_false.key) != false);
821
822 WARN_ON(!static_branch_likely(&sk_true));
823 WARN_ON(!static_branch_unlikely(&sk_true));
824 WARN_ON(static_branch_likely(&sk_false));
825 WARN_ON(static_branch_unlikely(&sk_false));
826
827 static_branch_disable(&sk_true);
828 static_branch_enable(&sk_false);
829
830 WARN_ON(static_key_enabled(&sk_true.key) == true);
831 WARN_ON(static_key_enabled(&sk_false.key) == false);
832
833 WARN_ON(static_branch_likely(&sk_true));
834 WARN_ON(static_branch_unlikely(&sk_true));
835 WARN_ON(!static_branch_likely(&sk_false));
836 WARN_ON(!static_branch_unlikely(&sk_false));
837
838 static_branch_enable(&sk_true);
839 static_branch_disable(&sk_false);
840 }
841
842 return 0;
843}
Jason Baron92ee46e2017-11-13 16:48:47 -0500844early_initcall(jump_label_test);
Peter Zijlstra1987c942015-07-27 18:32:09 +0200845#endif /* STATIC_KEYS_SELFTEST */