Root/
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 */ |
20 | static DEFINE_MUTEX(jump_label_mutex); |
21 | |
22 | void jump_label_lock(void) |
23 | { |
24 | mutex_lock(&jump_label_mutex); |
25 | } |
26 | |
27 | void jump_label_unlock(void) |
28 | { |
29 | mutex_unlock(&jump_label_mutex); |
30 | } |
31 | |
32 | static 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 | |
46 | static void |
47 | jump_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 | |
56 | static void jump_label_update(struct static_key *key, int enable); |
57 | |
58 | void 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 | } |
73 | EXPORT_SYMBOL_GPL(static_key_slow_inc); |
74 | |
75 | static 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 | |
96 | static 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 | |
103 | void static_key_slow_dec(struct static_key *key) |
104 | { |
105 | __static_key_slow_dec(key, 0, NULL); |
106 | } |
107 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
108 | |
109 | void static_key_slow_dec_deferred(struct static_key_deferred *key) |
110 | { |
111 | __static_key_slow_dec(&key->key, key->timeout, &key->work); |
112 | } |
113 | EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); |
114 | |
115 | void 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 | |
122 | static 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 | |
131 | static 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 | */ |
152 | void __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 | |
158 | static 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 | |
175 | static 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 | |
186 | void __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 | |
218 | struct static_key_mod { |
219 | struct static_key_mod *next; |
220 | struct jump_entry *entries; |
221 | struct module *mod; |
222 | }; |
223 | |
224 | static 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 | |
239 | static 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 | */ |
261 | void 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 | |
276 | static 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 | |
321 | static 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 | |
353 | static 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 | |
365 | static int |
366 | jump_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 | |
395 | struct notifier_block jump_label_module_nb = { |
396 | .notifier_call = jump_label_module_notify, |
397 | .priority = 1, /* higher than tracepoints */ |
398 | }; |
399 | |
400 | static __init int jump_label_init_module(void) |
401 | { |
402 | return register_module_notifier(&jump_label_module_nb); |
403 | } |
404 | early_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 | */ |
421 | int 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 | |
435 | static 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 |
454 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9