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9183c3f9 JP |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <linux/init.h> | |
3 | #include <linux/static_call.h> | |
4 | #include <linux/bug.h> | |
5 | #include <linux/smp.h> | |
6 | #include <linux/sort.h> | |
7 | #include <linux/slab.h> | |
8 | #include <linux/module.h> | |
9 | #include <linux/cpu.h> | |
10 | #include <linux/processor.h> | |
11 | #include <asm/sections.h> | |
12 | ||
13 | extern struct static_call_site __start_static_call_sites[], | |
14 | __stop_static_call_sites[]; | |
15 | ||
16 | static bool static_call_initialized; | |
17 | ||
9183c3f9 JP |
18 | /* mutex to protect key modules/sites */ |
19 | static DEFINE_MUTEX(static_call_mutex); | |
20 | ||
21 | static void static_call_lock(void) | |
22 | { | |
23 | mutex_lock(&static_call_mutex); | |
24 | } | |
25 | ||
26 | static void static_call_unlock(void) | |
27 | { | |
28 | mutex_unlock(&static_call_mutex); | |
29 | } | |
30 | ||
31 | static inline void *static_call_addr(struct static_call_site *site) | |
32 | { | |
33 | return (void *)((long)site->addr + (long)&site->addr); | |
34 | } | |
35 | ||
36 | ||
37 | static inline struct static_call_key *static_call_key(const struct static_call_site *site) | |
38 | { | |
39 | return (struct static_call_key *) | |
5b06fd3b | 40 | (((long)site->key + (long)&site->key) & ~STATIC_CALL_SITE_FLAGS); |
9183c3f9 JP |
41 | } |
42 | ||
43 | /* These assume the key is word-aligned. */ | |
44 | static inline bool static_call_is_init(struct static_call_site *site) | |
45 | { | |
5b06fd3b PZ |
46 | return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_INIT; |
47 | } | |
48 | ||
49 | static inline bool static_call_is_tail(struct static_call_site *site) | |
50 | { | |
51 | return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_TAIL; | |
9183c3f9 JP |
52 | } |
53 | ||
54 | static inline void static_call_set_init(struct static_call_site *site) | |
55 | { | |
5b06fd3b | 56 | site->key = ((long)static_call_key(site) | STATIC_CALL_SITE_INIT) - |
9183c3f9 JP |
57 | (long)&site->key; |
58 | } | |
59 | ||
60 | static int static_call_site_cmp(const void *_a, const void *_b) | |
61 | { | |
62 | const struct static_call_site *a = _a; | |
63 | const struct static_call_site *b = _b; | |
64 | const struct static_call_key *key_a = static_call_key(a); | |
65 | const struct static_call_key *key_b = static_call_key(b); | |
66 | ||
67 | if (key_a < key_b) | |
68 | return -1; | |
69 | ||
70 | if (key_a > key_b) | |
71 | return 1; | |
72 | ||
73 | return 0; | |
74 | } | |
75 | ||
76 | static void static_call_site_swap(void *_a, void *_b, int size) | |
77 | { | |
78 | long delta = (unsigned long)_a - (unsigned long)_b; | |
79 | struct static_call_site *a = _a; | |
80 | struct static_call_site *b = _b; | |
81 | struct static_call_site tmp = *a; | |
82 | ||
83 | a->addr = b->addr - delta; | |
84 | a->key = b->key - delta; | |
85 | ||
86 | b->addr = tmp.addr + delta; | |
87 | b->key = tmp.key + delta; | |
88 | } | |
89 | ||
90 | static inline void static_call_sort_entries(struct static_call_site *start, | |
91 | struct static_call_site *stop) | |
92 | { | |
93 | sort(start, stop - start, sizeof(struct static_call_site), | |
94 | static_call_site_cmp, static_call_site_swap); | |
95 | } | |
96 | ||
97 | void __static_call_update(struct static_call_key *key, void *tramp, void *func) | |
98 | { | |
99 | struct static_call_site *site, *stop; | |
100 | struct static_call_mod *site_mod; | |
101 | ||
102 | cpus_read_lock(); | |
103 | static_call_lock(); | |
104 | ||
105 | if (key->func == func) | |
106 | goto done; | |
107 | ||
108 | key->func = func; | |
109 | ||
5b06fd3b | 110 | arch_static_call_transform(NULL, tramp, func, false); |
9183c3f9 JP |
111 | |
112 | /* | |
113 | * If uninitialized, we'll not update the callsites, but they still | |
114 | * point to the trampoline and we just patched that. | |
115 | */ | |
116 | if (WARN_ON_ONCE(!static_call_initialized)) | |
117 | goto done; | |
118 | ||
119 | for (site_mod = key->mods; site_mod; site_mod = site_mod->next) { | |
120 | struct module *mod = site_mod->mod; | |
121 | ||
122 | if (!site_mod->sites) { | |
123 | /* | |
124 | * This can happen if the static call key is defined in | |
125 | * a module which doesn't use it. | |
126 | */ | |
127 | continue; | |
128 | } | |
129 | ||
130 | stop = __stop_static_call_sites; | |
131 | ||
132 | #ifdef CONFIG_MODULES | |
133 | if (mod) { | |
134 | stop = mod->static_call_sites + | |
135 | mod->num_static_call_sites; | |
136 | } | |
137 | #endif | |
138 | ||
139 | for (site = site_mod->sites; | |
140 | site < stop && static_call_key(site) == key; site++) { | |
141 | void *site_addr = static_call_addr(site); | |
142 | ||
143 | if (static_call_is_init(site)) { | |
144 | /* | |
145 | * Don't write to call sites which were in | |
146 | * initmem and have since been freed. | |
147 | */ | |
148 | if (!mod && system_state >= SYSTEM_RUNNING) | |
149 | continue; | |
150 | if (mod && !within_module_init((unsigned long)site_addr, mod)) | |
151 | continue; | |
152 | } | |
153 | ||
154 | if (!kernel_text_address((unsigned long)site_addr)) { | |
155 | WARN_ONCE(1, "can't patch static call site at %pS", | |
156 | site_addr); | |
157 | continue; | |
158 | } | |
159 | ||
5b06fd3b PZ |
160 | arch_static_call_transform(site_addr, NULL, func, |
161 | static_call_is_tail(site)); | |
9183c3f9 JP |
162 | } |
163 | } | |
164 | ||
165 | done: | |
166 | static_call_unlock(); | |
167 | cpus_read_unlock(); | |
168 | } | |
169 | EXPORT_SYMBOL_GPL(__static_call_update); | |
170 | ||
171 | static int __static_call_init(struct module *mod, | |
172 | struct static_call_site *start, | |
173 | struct static_call_site *stop) | |
174 | { | |
175 | struct static_call_site *site; | |
176 | struct static_call_key *key, *prev_key = NULL; | |
177 | struct static_call_mod *site_mod; | |
178 | ||
179 | if (start == stop) | |
180 | return 0; | |
181 | ||
182 | static_call_sort_entries(start, stop); | |
183 | ||
184 | for (site = start; site < stop; site++) { | |
185 | void *site_addr = static_call_addr(site); | |
186 | ||
187 | if ((mod && within_module_init((unsigned long)site_addr, mod)) || | |
188 | (!mod && init_section_contains(site_addr, 1))) | |
189 | static_call_set_init(site); | |
190 | ||
191 | key = static_call_key(site); | |
192 | if (key != prev_key) { | |
193 | prev_key = key; | |
194 | ||
195 | site_mod = kzalloc(sizeof(*site_mod), GFP_KERNEL); | |
196 | if (!site_mod) | |
197 | return -ENOMEM; | |
198 | ||
199 | site_mod->mod = mod; | |
200 | site_mod->sites = site; | |
201 | site_mod->next = key->mods; | |
202 | key->mods = site_mod; | |
203 | } | |
204 | ||
5b06fd3b PZ |
205 | arch_static_call_transform(site_addr, NULL, key->func, |
206 | static_call_is_tail(site)); | |
9183c3f9 JP |
207 | } |
208 | ||
209 | return 0; | |
210 | } | |
211 | ||
6333e8f7 PZ |
212 | static int addr_conflict(struct static_call_site *site, void *start, void *end) |
213 | { | |
214 | unsigned long addr = (unsigned long)static_call_addr(site); | |
215 | ||
216 | if (addr <= (unsigned long)end && | |
217 | addr + CALL_INSN_SIZE > (unsigned long)start) | |
218 | return 1; | |
219 | ||
220 | return 0; | |
221 | } | |
222 | ||
223 | static int __static_call_text_reserved(struct static_call_site *iter_start, | |
224 | struct static_call_site *iter_stop, | |
225 | void *start, void *end) | |
226 | { | |
227 | struct static_call_site *iter = iter_start; | |
228 | ||
229 | while (iter < iter_stop) { | |
230 | if (addr_conflict(iter, start, end)) | |
231 | return 1; | |
232 | iter++; | |
233 | } | |
234 | ||
235 | return 0; | |
236 | } | |
237 | ||
9183c3f9 JP |
238 | #ifdef CONFIG_MODULES |
239 | ||
6333e8f7 PZ |
240 | static int __static_call_mod_text_reserved(void *start, void *end) |
241 | { | |
242 | struct module *mod; | |
243 | int ret; | |
244 | ||
245 | preempt_disable(); | |
246 | mod = __module_text_address((unsigned long)start); | |
247 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); | |
248 | if (!try_module_get(mod)) | |
249 | mod = NULL; | |
250 | preempt_enable(); | |
251 | ||
252 | if (!mod) | |
253 | return 0; | |
254 | ||
255 | ret = __static_call_text_reserved(mod->static_call_sites, | |
256 | mod->static_call_sites + mod->num_static_call_sites, | |
257 | start, end); | |
258 | ||
259 | module_put(mod); | |
260 | ||
261 | return ret; | |
262 | } | |
263 | ||
9183c3f9 JP |
264 | static int static_call_add_module(struct module *mod) |
265 | { | |
266 | return __static_call_init(mod, mod->static_call_sites, | |
267 | mod->static_call_sites + mod->num_static_call_sites); | |
268 | } | |
269 | ||
270 | static void static_call_del_module(struct module *mod) | |
271 | { | |
272 | struct static_call_site *start = mod->static_call_sites; | |
273 | struct static_call_site *stop = mod->static_call_sites + | |
274 | mod->num_static_call_sites; | |
275 | struct static_call_key *key, *prev_key = NULL; | |
276 | struct static_call_mod *site_mod, **prev; | |
277 | struct static_call_site *site; | |
278 | ||
279 | for (site = start; site < stop; site++) { | |
280 | key = static_call_key(site); | |
281 | if (key == prev_key) | |
282 | continue; | |
283 | ||
284 | prev_key = key; | |
285 | ||
286 | for (prev = &key->mods, site_mod = key->mods; | |
287 | site_mod && site_mod->mod != mod; | |
288 | prev = &site_mod->next, site_mod = site_mod->next) | |
289 | ; | |
290 | ||
291 | if (!site_mod) | |
292 | continue; | |
293 | ||
294 | *prev = site_mod->next; | |
295 | kfree(site_mod); | |
296 | } | |
297 | } | |
298 | ||
299 | static int static_call_module_notify(struct notifier_block *nb, | |
300 | unsigned long val, void *data) | |
301 | { | |
302 | struct module *mod = data; | |
303 | int ret = 0; | |
304 | ||
305 | cpus_read_lock(); | |
306 | static_call_lock(); | |
307 | ||
308 | switch (val) { | |
309 | case MODULE_STATE_COMING: | |
310 | ret = static_call_add_module(mod); | |
311 | if (ret) { | |
312 | WARN(1, "Failed to allocate memory for static calls"); | |
313 | static_call_del_module(mod); | |
314 | } | |
315 | break; | |
316 | case MODULE_STATE_GOING: | |
317 | static_call_del_module(mod); | |
318 | break; | |
319 | } | |
320 | ||
321 | static_call_unlock(); | |
322 | cpus_read_unlock(); | |
323 | ||
324 | return notifier_from_errno(ret); | |
325 | } | |
326 | ||
327 | static struct notifier_block static_call_module_nb = { | |
328 | .notifier_call = static_call_module_notify, | |
329 | }; | |
330 | ||
6333e8f7 PZ |
331 | #else |
332 | ||
333 | static inline int __static_call_mod_text_reserved(void *start, void *end) | |
334 | { | |
335 | return 0; | |
336 | } | |
337 | ||
9183c3f9 JP |
338 | #endif /* CONFIG_MODULES */ |
339 | ||
6333e8f7 PZ |
340 | int static_call_text_reserved(void *start, void *end) |
341 | { | |
342 | int ret = __static_call_text_reserved(__start_static_call_sites, | |
343 | __stop_static_call_sites, start, end); | |
344 | ||
345 | if (ret) | |
346 | return ret; | |
347 | ||
348 | return __static_call_mod_text_reserved(start, end); | |
349 | } | |
350 | ||
9183c3f9 JP |
351 | static void __init static_call_init(void) |
352 | { | |
353 | int ret; | |
354 | ||
355 | if (static_call_initialized) | |
356 | return; | |
357 | ||
358 | cpus_read_lock(); | |
359 | static_call_lock(); | |
360 | ret = __static_call_init(NULL, __start_static_call_sites, | |
361 | __stop_static_call_sites); | |
362 | static_call_unlock(); | |
363 | cpus_read_unlock(); | |
364 | ||
365 | if (ret) { | |
366 | pr_err("Failed to allocate memory for static_call!\n"); | |
367 | BUG(); | |
368 | } | |
369 | ||
370 | static_call_initialized = true; | |
371 | ||
372 | #ifdef CONFIG_MODULES | |
373 | register_module_notifier(&static_call_module_nb); | |
374 | #endif | |
375 | } | |
376 | early_initcall(static_call_init); | |
f03c4129 PZ |
377 | |
378 | #ifdef CONFIG_STATIC_CALL_SELFTEST | |
379 | ||
380 | static int func_a(int x) | |
381 | { | |
382 | return x+1; | |
383 | } | |
384 | ||
385 | static int func_b(int x) | |
386 | { | |
387 | return x+2; | |
388 | } | |
389 | ||
390 | DEFINE_STATIC_CALL(sc_selftest, func_a); | |
391 | ||
392 | static struct static_call_data { | |
393 | int (*func)(int); | |
394 | int val; | |
395 | int expect; | |
396 | } static_call_data [] __initdata = { | |
397 | { NULL, 2, 3 }, | |
398 | { func_b, 2, 4 }, | |
399 | { func_a, 2, 3 } | |
400 | }; | |
401 | ||
402 | static int __init test_static_call_init(void) | |
403 | { | |
404 | int i; | |
405 | ||
406 | for (i = 0; i < ARRAY_SIZE(static_call_data); i++ ) { | |
407 | struct static_call_data *scd = &static_call_data[i]; | |
408 | ||
409 | if (scd->func) | |
410 | static_call_update(sc_selftest, scd->func); | |
411 | ||
412 | WARN_ON(static_call(sc_selftest)(scd->val) != scd->expect); | |
413 | } | |
414 | ||
415 | return 0; | |
416 | } | |
417 | early_initcall(test_static_call_init); | |
418 | ||
419 | #endif /* CONFIG_STATIC_CALL_SELFTEST */ |