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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
5c9a8750 DV |
2 | #define pr_fmt(fmt) "kcov: " fmt |
3 | ||
36f05ae8 | 4 | #define DISABLE_BRANCH_PROFILING |
db862358 | 5 | #include <linux/atomic.h> |
5c9a8750 | 6 | #include <linux/compiler.h> |
db862358 KW |
7 | #include <linux/errno.h> |
8 | #include <linux/export.h> | |
5c9a8750 DV |
9 | #include <linux/types.h> |
10 | #include <linux/file.h> | |
11 | #include <linux/fs.h> | |
eec028c9 | 12 | #include <linux/hashtable.h> |
db862358 | 13 | #include <linux/init.h> |
74d89909 | 14 | #include <linux/kmsan-checks.h> |
5c9a8750 | 15 | #include <linux/mm.h> |
db862358 | 16 | #include <linux/preempt.h> |
5c9a8750 | 17 | #include <linux/printk.h> |
166ad0e1 | 18 | #include <linux/sched.h> |
5c9a8750 DV |
19 | #include <linux/slab.h> |
20 | #include <linux/spinlock.h> | |
21 | #include <linux/vmalloc.h> | |
22 | #include <linux/debugfs.h> | |
23 | #include <linux/uaccess.h> | |
24 | #include <linux/kcov.h> | |
39e07cb6 | 25 | #include <linux/refcount.h> |
eec028c9 | 26 | #include <linux/log2.h> |
4983f0ab | 27 | #include <asm/setup.h> |
5c9a8750 | 28 | |
eec028c9 AK |
29 | #define kcov_debug(fmt, ...) pr_debug("%s: " fmt, __func__, ##__VA_ARGS__) |
30 | ||
ded97d2c VC |
31 | /* Number of 64-bit words written per one comparison: */ |
32 | #define KCOV_WORDS_PER_CMP 4 | |
33 | ||
5c9a8750 DV |
34 | /* |
35 | * kcov descriptor (one per opened debugfs file). | |
36 | * State transitions of the descriptor: | |
37 | * - initial state after open() | |
38 | * - then there must be a single ioctl(KCOV_INIT_TRACE) call | |
39 | * - then, mmap() call (several calls are allowed but not useful) | |
ded97d2c VC |
40 | * - then, ioctl(KCOV_ENABLE, arg), where arg is |
41 | * KCOV_TRACE_PC - to trace only the PCs | |
42 | * or | |
43 | * KCOV_TRACE_CMP - to trace only the comparison operands | |
44 | * - then, ioctl(KCOV_DISABLE) to disable the task. | |
45 | * Enabling/disabling ioctls can be repeated (only one task a time allowed). | |
5c9a8750 DV |
46 | */ |
47 | struct kcov { | |
48 | /* | |
49 | * Reference counter. We keep one for: | |
50 | * - opened file descriptor | |
51 | * - task with enabled coverage (we can't unwire it from another task) | |
eec028c9 | 52 | * - each code section for remote coverage collection |
5c9a8750 | 53 | */ |
39e07cb6 | 54 | refcount_t refcount; |
5c9a8750 DV |
55 | /* The lock protects mode, size, area and t. */ |
56 | spinlock_t lock; | |
57 | enum kcov_mode mode; | |
eec028c9 AK |
58 | /* Size of arena (in long's). */ |
59 | unsigned int size; | |
5c9a8750 DV |
60 | /* Coverage buffer shared with user space. */ |
61 | void *area; | |
62 | /* Task for which we collect coverage, or NULL. */ | |
63 | struct task_struct *t; | |
eec028c9 AK |
64 | /* Collecting coverage from remote (background) threads. */ |
65 | bool remote; | |
66 | /* Size of remote area (in long's). */ | |
67 | unsigned int remote_size; | |
68 | /* | |
69 | * Sequence is incremented each time kcov is reenabled, used by | |
70 | * kcov_remote_stop(), see the comment there. | |
71 | */ | |
72 | int sequence; | |
5c9a8750 DV |
73 | }; |
74 | ||
eec028c9 AK |
75 | struct kcov_remote_area { |
76 | struct list_head list; | |
77 | unsigned int size; | |
78 | }; | |
79 | ||
80 | struct kcov_remote { | |
81 | u64 handle; | |
82 | struct kcov *kcov; | |
83 | struct hlist_node hnode; | |
84 | }; | |
85 | ||
86 | static DEFINE_SPINLOCK(kcov_remote_lock); | |
87 | static DEFINE_HASHTABLE(kcov_remote_map, 4); | |
88 | static struct list_head kcov_remote_areas = LIST_HEAD_INIT(kcov_remote_areas); | |
89 | ||
5ff3b30a AK |
90 | struct kcov_percpu_data { |
91 | void *irq_area; | |
d5d2c51f | 92 | local_lock_t lock; |
5ff3b30a AK |
93 | |
94 | unsigned int saved_mode; | |
95 | unsigned int saved_size; | |
96 | void *saved_area; | |
97 | struct kcov *saved_kcov; | |
98 | int saved_sequence; | |
99 | }; | |
100 | ||
d5d2c51f SAS |
101 | static DEFINE_PER_CPU(struct kcov_percpu_data, kcov_percpu_data) = { |
102 | .lock = INIT_LOCAL_LOCK(lock), | |
103 | }; | |
5ff3b30a | 104 | |
eec028c9 AK |
105 | /* Must be called with kcov_remote_lock locked. */ |
106 | static struct kcov_remote *kcov_remote_find(u64 handle) | |
107 | { | |
108 | struct kcov_remote *remote; | |
109 | ||
110 | hash_for_each_possible(kcov_remote_map, remote, hnode, handle) { | |
111 | if (remote->handle == handle) | |
112 | return remote; | |
113 | } | |
114 | return NULL; | |
115 | } | |
116 | ||
3c61df38 | 117 | /* Must be called with kcov_remote_lock locked. */ |
eec028c9 AK |
118 | static struct kcov_remote *kcov_remote_add(struct kcov *kcov, u64 handle) |
119 | { | |
120 | struct kcov_remote *remote; | |
121 | ||
122 | if (kcov_remote_find(handle)) | |
123 | return ERR_PTR(-EEXIST); | |
124 | remote = kmalloc(sizeof(*remote), GFP_ATOMIC); | |
125 | if (!remote) | |
126 | return ERR_PTR(-ENOMEM); | |
127 | remote->handle = handle; | |
128 | remote->kcov = kcov; | |
129 | hash_add(kcov_remote_map, &remote->hnode, handle); | |
130 | return remote; | |
131 | } | |
132 | ||
133 | /* Must be called with kcov_remote_lock locked. */ | |
134 | static struct kcov_remote_area *kcov_remote_area_get(unsigned int size) | |
135 | { | |
136 | struct kcov_remote_area *area; | |
137 | struct list_head *pos; | |
138 | ||
eec028c9 AK |
139 | list_for_each(pos, &kcov_remote_areas) { |
140 | area = list_entry(pos, struct kcov_remote_area, list); | |
141 | if (area->size == size) { | |
142 | list_del(&area->list); | |
eec028c9 AK |
143 | return area; |
144 | } | |
145 | } | |
eec028c9 AK |
146 | return NULL; |
147 | } | |
148 | ||
149 | /* Must be called with kcov_remote_lock locked. */ | |
150 | static void kcov_remote_area_put(struct kcov_remote_area *area, | |
151 | unsigned int size) | |
152 | { | |
eec028c9 AK |
153 | INIT_LIST_HEAD(&area->list); |
154 | area->size = size; | |
155 | list_add(&area->list, &kcov_remote_areas); | |
74d89909 AP |
156 | /* |
157 | * KMSAN doesn't instrument this file, so it may not know area->list | |
158 | * is initialized. Unpoison it explicitly to avoid reports in | |
159 | * kcov_remote_area_get(). | |
160 | */ | |
161 | kmsan_unpoison_memory(&area->list, sizeof(area->list)); | |
eec028c9 AK |
162 | } |
163 | ||
903e8ff8 | 164 | static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t) |
5c9a8750 | 165 | { |
0ed557aa | 166 | unsigned int mode; |
5c9a8750 | 167 | |
5c9a8750 DV |
168 | /* |
169 | * We are interested in code coverage as a function of a syscall inputs, | |
5ff3b30a AK |
170 | * so we ignore code executed in interrupts, unless we are in a remote |
171 | * coverage collection section in a softirq. | |
5c9a8750 | 172 | */ |
5ff3b30a | 173 | if (!in_task() && !(in_serving_softirq() && t->kcov_softirq)) |
ded97d2c | 174 | return false; |
5c9a8750 | 175 | mode = READ_ONCE(t->kcov_mode); |
ded97d2c VC |
176 | /* |
177 | * There is some code that runs in interrupts but for which | |
178 | * in_interrupt() returns false (e.g. preempt_schedule_irq()). | |
179 | * READ_ONCE()/barrier() effectively provides load-acquire wrt | |
180 | * interrupts, there are paired barrier()/WRITE_ONCE() in | |
eec028c9 | 181 | * kcov_start(). |
ded97d2c VC |
182 | */ |
183 | barrier(); | |
184 | return mode == needed_mode; | |
185 | } | |
4983f0ab | 186 | |
903e8ff8 | 187 | static notrace unsigned long canonicalize_ip(unsigned long ip) |
ded97d2c | 188 | { |
4983f0ab | 189 | #ifdef CONFIG_RANDOMIZE_BASE |
ded97d2c | 190 | ip -= kaslr_offset(); |
4983f0ab | 191 | #endif |
ded97d2c VC |
192 | return ip; |
193 | } | |
5c9a8750 | 194 | |
ded97d2c VC |
195 | /* |
196 | * Entry point from instrumented code. | |
197 | * This is called once per basic-block/edge. | |
198 | */ | |
199 | void notrace __sanitizer_cov_trace_pc(void) | |
200 | { | |
201 | struct task_struct *t; | |
202 | unsigned long *area; | |
203 | unsigned long ip = canonicalize_ip(_RET_IP_); | |
204 | unsigned long pos; | |
205 | ||
206 | t = current; | |
207 | if (!check_kcov_mode(KCOV_MODE_TRACE_PC, t)) | |
208 | return; | |
209 | ||
210 | area = t->kcov_area; | |
211 | /* The first 64-bit word is the number of subsequent PCs. */ | |
212 | pos = READ_ONCE(area[0]) + 1; | |
213 | if (likely(pos < t->kcov_size)) { | |
3159d79b CL |
214 | /* Previously we write pc before updating pos. However, some |
215 | * early interrupt code could bypass check_kcov_mode() check | |
216 | * and invoke __sanitizer_cov_trace_pc(). If such interrupt is | |
217 | * raised between writing pc and updating pos, the pc could be | |
218 | * overitten by the recursive __sanitizer_cov_trace_pc(). | |
219 | * Update pos before writing pc to avoid such interleaving. | |
220 | */ | |
ded97d2c | 221 | WRITE_ONCE(area[0], pos); |
3159d79b CL |
222 | barrier(); |
223 | area[pos] = ip; | |
5c9a8750 DV |
224 | } |
225 | } | |
226 | EXPORT_SYMBOL(__sanitizer_cov_trace_pc); | |
227 | ||
ded97d2c | 228 | #ifdef CONFIG_KCOV_ENABLE_COMPARISONS |
63472443 | 229 | static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip) |
ded97d2c VC |
230 | { |
231 | struct task_struct *t; | |
232 | u64 *area; | |
233 | u64 count, start_index, end_pos, max_pos; | |
234 | ||
235 | t = current; | |
236 | if (!check_kcov_mode(KCOV_MODE_TRACE_CMP, t)) | |
237 | return; | |
238 | ||
239 | ip = canonicalize_ip(ip); | |
240 | ||
241 | /* | |
242 | * We write all comparison arguments and types as u64. | |
243 | * The buffer was allocated for t->kcov_size unsigned longs. | |
244 | */ | |
245 | area = (u64 *)t->kcov_area; | |
246 | max_pos = t->kcov_size * sizeof(unsigned long); | |
247 | ||
248 | count = READ_ONCE(area[0]); | |
249 | ||
250 | /* Every record is KCOV_WORDS_PER_CMP 64-bit words. */ | |
251 | start_index = 1 + count * KCOV_WORDS_PER_CMP; | |
252 | end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64); | |
253 | if (likely(end_pos <= max_pos)) { | |
3159d79b CL |
254 | /* See comment in __sanitizer_cov_trace_pc(). */ |
255 | WRITE_ONCE(area[0], count + 1); | |
256 | barrier(); | |
ded97d2c VC |
257 | area[start_index] = type; |
258 | area[start_index + 1] = arg1; | |
259 | area[start_index + 2] = arg2; | |
260 | area[start_index + 3] = ip; | |
ded97d2c VC |
261 | } |
262 | } | |
263 | ||
264 | void notrace __sanitizer_cov_trace_cmp1(u8 arg1, u8 arg2) | |
265 | { | |
266 | write_comp_data(KCOV_CMP_SIZE(0), arg1, arg2, _RET_IP_); | |
267 | } | |
268 | EXPORT_SYMBOL(__sanitizer_cov_trace_cmp1); | |
269 | ||
270 | void notrace __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2) | |
271 | { | |
272 | write_comp_data(KCOV_CMP_SIZE(1), arg1, arg2, _RET_IP_); | |
273 | } | |
274 | EXPORT_SYMBOL(__sanitizer_cov_trace_cmp2); | |
275 | ||
689d77f0 | 276 | void notrace __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2) |
ded97d2c VC |
277 | { |
278 | write_comp_data(KCOV_CMP_SIZE(2), arg1, arg2, _RET_IP_); | |
279 | } | |
280 | EXPORT_SYMBOL(__sanitizer_cov_trace_cmp4); | |
281 | ||
e0ddec73 | 282 | void notrace __sanitizer_cov_trace_cmp8(kcov_u64 arg1, kcov_u64 arg2) |
ded97d2c VC |
283 | { |
284 | write_comp_data(KCOV_CMP_SIZE(3), arg1, arg2, _RET_IP_); | |
285 | } | |
286 | EXPORT_SYMBOL(__sanitizer_cov_trace_cmp8); | |
287 | ||
288 | void notrace __sanitizer_cov_trace_const_cmp1(u8 arg1, u8 arg2) | |
289 | { | |
290 | write_comp_data(KCOV_CMP_SIZE(0) | KCOV_CMP_CONST, arg1, arg2, | |
291 | _RET_IP_); | |
292 | } | |
293 | EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp1); | |
294 | ||
295 | void notrace __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2) | |
296 | { | |
297 | write_comp_data(KCOV_CMP_SIZE(1) | KCOV_CMP_CONST, arg1, arg2, | |
298 | _RET_IP_); | |
299 | } | |
300 | EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp2); | |
301 | ||
689d77f0 | 302 | void notrace __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2) |
ded97d2c VC |
303 | { |
304 | write_comp_data(KCOV_CMP_SIZE(2) | KCOV_CMP_CONST, arg1, arg2, | |
305 | _RET_IP_); | |
306 | } | |
307 | EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp4); | |
308 | ||
e0ddec73 | 309 | void notrace __sanitizer_cov_trace_const_cmp8(kcov_u64 arg1, kcov_u64 arg2) |
ded97d2c VC |
310 | { |
311 | write_comp_data(KCOV_CMP_SIZE(3) | KCOV_CMP_CONST, arg1, arg2, | |
312 | _RET_IP_); | |
313 | } | |
314 | EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp8); | |
315 | ||
e0ddec73 | 316 | void notrace __sanitizer_cov_trace_switch(kcov_u64 val, void *arg) |
ded97d2c VC |
317 | { |
318 | u64 i; | |
e0ddec73 | 319 | u64 *cases = arg; |
ded97d2c VC |
320 | u64 count = cases[0]; |
321 | u64 size = cases[1]; | |
322 | u64 type = KCOV_CMP_CONST; | |
323 | ||
324 | switch (size) { | |
325 | case 8: | |
326 | type |= KCOV_CMP_SIZE(0); | |
327 | break; | |
328 | case 16: | |
329 | type |= KCOV_CMP_SIZE(1); | |
330 | break; | |
331 | case 32: | |
332 | type |= KCOV_CMP_SIZE(2); | |
333 | break; | |
334 | case 64: | |
335 | type |= KCOV_CMP_SIZE(3); | |
336 | break; | |
337 | default: | |
338 | return; | |
339 | } | |
340 | for (i = 0; i < count; i++) | |
341 | write_comp_data(type, cases[i + 2], val, _RET_IP_); | |
342 | } | |
343 | EXPORT_SYMBOL(__sanitizer_cov_trace_switch); | |
344 | #endif /* ifdef CONFIG_KCOV_ENABLE_COMPARISONS */ | |
345 | ||
76484b1c AK |
346 | static void kcov_start(struct task_struct *t, struct kcov *kcov, |
347 | unsigned int size, void *area, enum kcov_mode mode, | |
348 | int sequence) | |
eec028c9 AK |
349 | { |
350 | kcov_debug("t = %px, size = %u, area = %px\n", t, size, area); | |
76484b1c | 351 | t->kcov = kcov; |
eec028c9 AK |
352 | /* Cache in task struct for performance. */ |
353 | t->kcov_size = size; | |
354 | t->kcov_area = area; | |
eeb91f9a | 355 | t->kcov_sequence = sequence; |
eec028c9 AK |
356 | /* See comment in check_kcov_mode(). */ |
357 | barrier(); | |
358 | WRITE_ONCE(t->kcov_mode, mode); | |
eec028c9 AK |
359 | } |
360 | ||
361 | static void kcov_stop(struct task_struct *t) | |
362 | { | |
363 | WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED); | |
364 | barrier(); | |
76484b1c | 365 | t->kcov = NULL; |
eec028c9 AK |
366 | t->kcov_size = 0; |
367 | t->kcov_area = NULL; | |
368 | } | |
369 | ||
370 | static void kcov_task_reset(struct task_struct *t) | |
371 | { | |
372 | kcov_stop(t); | |
eec028c9 AK |
373 | t->kcov_sequence = 0; |
374 | t->kcov_handle = 0; | |
375 | } | |
376 | ||
377 | void kcov_task_init(struct task_struct *t) | |
378 | { | |
379 | kcov_task_reset(t); | |
380 | t->kcov_handle = current->kcov_handle; | |
381 | } | |
382 | ||
383 | static void kcov_reset(struct kcov *kcov) | |
384 | { | |
385 | kcov->t = NULL; | |
386 | kcov->mode = KCOV_MODE_INIT; | |
387 | kcov->remote = false; | |
388 | kcov->remote_size = 0; | |
389 | kcov->sequence++; | |
390 | } | |
391 | ||
392 | static void kcov_remote_reset(struct kcov *kcov) | |
393 | { | |
394 | int bkt; | |
395 | struct kcov_remote *remote; | |
396 | struct hlist_node *tmp; | |
5ff3b30a | 397 | unsigned long flags; |
eec028c9 | 398 | |
5ff3b30a | 399 | spin_lock_irqsave(&kcov_remote_lock, flags); |
eec028c9 AK |
400 | hash_for_each_safe(kcov_remote_map, bkt, tmp, remote, hnode) { |
401 | if (remote->kcov != kcov) | |
402 | continue; | |
eec028c9 AK |
403 | hash_del(&remote->hnode); |
404 | kfree(remote); | |
405 | } | |
406 | /* Do reset before unlock to prevent races with kcov_remote_start(). */ | |
407 | kcov_reset(kcov); | |
5ff3b30a | 408 | spin_unlock_irqrestore(&kcov_remote_lock, flags); |
eec028c9 AK |
409 | } |
410 | ||
411 | static void kcov_disable(struct task_struct *t, struct kcov *kcov) | |
412 | { | |
413 | kcov_task_reset(t); | |
414 | if (kcov->remote) | |
415 | kcov_remote_reset(kcov); | |
416 | else | |
417 | kcov_reset(kcov); | |
418 | } | |
419 | ||
5c9a8750 DV |
420 | static void kcov_get(struct kcov *kcov) |
421 | { | |
39e07cb6 | 422 | refcount_inc(&kcov->refcount); |
5c9a8750 DV |
423 | } |
424 | ||
425 | static void kcov_put(struct kcov *kcov) | |
426 | { | |
39e07cb6 | 427 | if (refcount_dec_and_test(&kcov->refcount)) { |
eec028c9 | 428 | kcov_remote_reset(kcov); |
5c9a8750 DV |
429 | vfree(kcov->area); |
430 | kfree(kcov); | |
431 | } | |
432 | } | |
433 | ||
5c9a8750 DV |
434 | void kcov_task_exit(struct task_struct *t) |
435 | { | |
436 | struct kcov *kcov; | |
5ff3b30a | 437 | unsigned long flags; |
5c9a8750 DV |
438 | |
439 | kcov = t->kcov; | |
440 | if (kcov == NULL) | |
441 | return; | |
eec028c9 | 442 | |
5ff3b30a | 443 | spin_lock_irqsave(&kcov->lock, flags); |
eec028c9 AK |
444 | kcov_debug("t = %px, kcov->t = %px\n", t, kcov->t); |
445 | /* | |
446 | * For KCOV_ENABLE devices we want to make sure that t->kcov->t == t, | |
447 | * which comes down to: | |
448 | * WARN_ON(!kcov->remote && kcov->t != t); | |
449 | * | |
450 | * For KCOV_REMOTE_ENABLE devices, the exiting task is either: | |
3021e692 AK |
451 | * |
452 | * 1. A remote task between kcov_remote_start() and kcov_remote_stop(). | |
eec028c9 AK |
453 | * In this case we should print a warning right away, since a task |
454 | * shouldn't be exiting when it's in a kcov coverage collection | |
455 | * section. Here t points to the task that is collecting remote | |
456 | * coverage, and t->kcov->t points to the thread that created the | |
457 | * kcov device. Which means that to detect this case we need to | |
458 | * check that t != t->kcov->t, and this gives us the following: | |
459 | * WARN_ON(kcov->remote && kcov->t != t); | |
460 | * | |
461 | * 2. The task that created kcov exiting without calling KCOV_DISABLE, | |
3021e692 | 462 | * and then again we make sure that t->kcov->t == t: |
eec028c9 AK |
463 | * WARN_ON(kcov->remote && kcov->t != t); |
464 | * | |
465 | * By combining all three checks into one we get: | |
466 | */ | |
5c9a8750 | 467 | if (WARN_ON(kcov->t != t)) { |
5ff3b30a | 468 | spin_unlock_irqrestore(&kcov->lock, flags); |
5c9a8750 DV |
469 | return; |
470 | } | |
471 | /* Just to not leave dangling references behind. */ | |
eec028c9 | 472 | kcov_disable(t, kcov); |
5ff3b30a | 473 | spin_unlock_irqrestore(&kcov->lock, flags); |
5c9a8750 DV |
474 | kcov_put(kcov); |
475 | } | |
476 | ||
477 | static int kcov_mmap(struct file *filep, struct vm_area_struct *vma) | |
478 | { | |
479 | int res = 0; | |
5c9a8750 DV |
480 | struct kcov *kcov = vma->vm_file->private_data; |
481 | unsigned long size, off; | |
482 | struct page *page; | |
5ff3b30a | 483 | unsigned long flags; |
5c9a8750 | 484 | |
5ff3b30a | 485 | spin_lock_irqsave(&kcov->lock, flags); |
5c9a8750 | 486 | size = kcov->size * sizeof(unsigned long); |
b3d7fe86 | 487 | if (kcov->area == NULL || vma->vm_pgoff != 0 || |
5c9a8750 DV |
488 | vma->vm_end - vma->vm_start != size) { |
489 | res = -EINVAL; | |
490 | goto exit; | |
491 | } | |
b3d7fe86 | 492 | spin_unlock_irqrestore(&kcov->lock, flags); |
1c71222e | 493 | vm_flags_set(vma, VM_DONTEXPAND); |
b3d7fe86 AN |
494 | for (off = 0; off < size; off += PAGE_SIZE) { |
495 | page = vmalloc_to_page(kcov->area + off); | |
ecc04463 AN |
496 | res = vm_insert_page(vma, vma->vm_start + off, page); |
497 | if (res) { | |
498 | pr_warn_once("kcov: vm_insert_page() failed\n"); | |
499 | return res; | |
500 | } | |
5c9a8750 | 501 | } |
b3d7fe86 | 502 | return 0; |
5c9a8750 | 503 | exit: |
5ff3b30a | 504 | spin_unlock_irqrestore(&kcov->lock, flags); |
5c9a8750 DV |
505 | return res; |
506 | } | |
507 | ||
508 | static int kcov_open(struct inode *inode, struct file *filep) | |
509 | { | |
510 | struct kcov *kcov; | |
511 | ||
512 | kcov = kzalloc(sizeof(*kcov), GFP_KERNEL); | |
513 | if (!kcov) | |
514 | return -ENOMEM; | |
ded97d2c | 515 | kcov->mode = KCOV_MODE_DISABLED; |
eec028c9 | 516 | kcov->sequence = 1; |
39e07cb6 | 517 | refcount_set(&kcov->refcount, 1); |
5c9a8750 DV |
518 | spin_lock_init(&kcov->lock); |
519 | filep->private_data = kcov; | |
520 | return nonseekable_open(inode, filep); | |
521 | } | |
522 | ||
523 | static int kcov_close(struct inode *inode, struct file *filep) | |
524 | { | |
525 | kcov_put(filep->private_data); | |
526 | return 0; | |
527 | } | |
528 | ||
eec028c9 AK |
529 | static int kcov_get_mode(unsigned long arg) |
530 | { | |
531 | if (arg == KCOV_TRACE_PC) | |
532 | return KCOV_MODE_TRACE_PC; | |
533 | else if (arg == KCOV_TRACE_CMP) | |
534 | #ifdef CONFIG_KCOV_ENABLE_COMPARISONS | |
535 | return KCOV_MODE_TRACE_CMP; | |
536 | #else | |
537 | return -ENOTSUPP; | |
538 | #endif | |
539 | else | |
540 | return -EINVAL; | |
541 | } | |
542 | ||
dc55daff MR |
543 | /* |
544 | * Fault in a lazily-faulted vmalloc area before it can be used by | |
545 | * __santizer_cov_trace_pc(), to avoid recursion issues if any code on the | |
546 | * vmalloc fault handling path is instrumented. | |
547 | */ | |
548 | static void kcov_fault_in_area(struct kcov *kcov) | |
549 | { | |
550 | unsigned long stride = PAGE_SIZE / sizeof(unsigned long); | |
551 | unsigned long *area = kcov->area; | |
552 | unsigned long offset; | |
553 | ||
554 | for (offset = 0; offset < kcov->size; offset += stride) | |
555 | READ_ONCE(area[offset]); | |
556 | } | |
557 | ||
eec028c9 AK |
558 | static inline bool kcov_check_handle(u64 handle, bool common_valid, |
559 | bool uncommon_valid, bool zero_valid) | |
560 | { | |
561 | if (handle & ~(KCOV_SUBSYSTEM_MASK | KCOV_INSTANCE_MASK)) | |
562 | return false; | |
563 | switch (handle & KCOV_SUBSYSTEM_MASK) { | |
564 | case KCOV_SUBSYSTEM_COMMON: | |
565 | return (handle & KCOV_INSTANCE_MASK) ? | |
566 | common_valid : zero_valid; | |
567 | case KCOV_SUBSYSTEM_USB: | |
568 | return uncommon_valid; | |
569 | default: | |
570 | return false; | |
571 | } | |
572 | return false; | |
573 | } | |
574 | ||
5c9a8750 DV |
575 | static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, |
576 | unsigned long arg) | |
577 | { | |
578 | struct task_struct *t; | |
17581aa1 | 579 | unsigned long flags, unused; |
eec028c9 AK |
580 | int mode, i; |
581 | struct kcov_remote_arg *remote_arg; | |
582 | struct kcov_remote *remote; | |
5c9a8750 DV |
583 | |
584 | switch (cmd) { | |
5c9a8750 DV |
585 | case KCOV_ENABLE: |
586 | /* | |
587 | * Enable coverage for the current task. | |
588 | * At this point user must have been enabled trace mode, | |
589 | * and mmapped the file. Coverage collection is disabled only | |
590 | * at task exit or voluntary by KCOV_DISABLE. After that it can | |
591 | * be enabled for another task. | |
592 | */ | |
ded97d2c | 593 | if (kcov->mode != KCOV_MODE_INIT || !kcov->area) |
5c9a8750 | 594 | return -EINVAL; |
a77660d2 DV |
595 | t = current; |
596 | if (kcov->t != NULL || t->kcov != NULL) | |
5c9a8750 | 597 | return -EBUSY; |
eec028c9 AK |
598 | mode = kcov_get_mode(arg); |
599 | if (mode < 0) | |
600 | return mode; | |
dc55daff | 601 | kcov_fault_in_area(kcov); |
eec028c9 | 602 | kcov->mode = mode; |
76484b1c | 603 | kcov_start(t, kcov, kcov->size, kcov->area, kcov->mode, |
eec028c9 | 604 | kcov->sequence); |
5c9a8750 | 605 | kcov->t = t; |
eec028c9 | 606 | /* Put either in kcov_task_exit() or in KCOV_DISABLE. */ |
5c9a8750 DV |
607 | kcov_get(kcov); |
608 | return 0; | |
609 | case KCOV_DISABLE: | |
610 | /* Disable coverage for the current task. */ | |
611 | unused = arg; | |
612 | if (unused != 0 || current->kcov != kcov) | |
613 | return -EINVAL; | |
614 | t = current; | |
615 | if (WARN_ON(kcov->t != t)) | |
616 | return -EINVAL; | |
eec028c9 | 617 | kcov_disable(t, kcov); |
5c9a8750 DV |
618 | kcov_put(kcov); |
619 | return 0; | |
eec028c9 | 620 | case KCOV_REMOTE_ENABLE: |
eec028c9 AK |
621 | if (kcov->mode != KCOV_MODE_INIT || !kcov->area) |
622 | return -EINVAL; | |
623 | t = current; | |
624 | if (kcov->t != NULL || t->kcov != NULL) | |
625 | return -EBUSY; | |
626 | remote_arg = (struct kcov_remote_arg *)arg; | |
627 | mode = kcov_get_mode(remote_arg->trace_mode); | |
628 | if (mode < 0) | |
629 | return mode; | |
56fd6162 AB |
630 | if ((unsigned long)remote_arg->area_size > |
631 | LONG_MAX / sizeof(unsigned long)) | |
eec028c9 AK |
632 | return -EINVAL; |
633 | kcov->mode = mode; | |
634 | t->kcov = kcov; | |
635 | kcov->t = t; | |
636 | kcov->remote = true; | |
637 | kcov->remote_size = remote_arg->area_size; | |
5ff3b30a | 638 | spin_lock_irqsave(&kcov_remote_lock, flags); |
eec028c9 | 639 | for (i = 0; i < remote_arg->num_handles; i++) { |
eec028c9 AK |
640 | if (!kcov_check_handle(remote_arg->handles[i], |
641 | false, true, false)) { | |
5ff3b30a AK |
642 | spin_unlock_irqrestore(&kcov_remote_lock, |
643 | flags); | |
eec028c9 AK |
644 | kcov_disable(t, kcov); |
645 | return -EINVAL; | |
646 | } | |
647 | remote = kcov_remote_add(kcov, remote_arg->handles[i]); | |
648 | if (IS_ERR(remote)) { | |
5ff3b30a AK |
649 | spin_unlock_irqrestore(&kcov_remote_lock, |
650 | flags); | |
eec028c9 AK |
651 | kcov_disable(t, kcov); |
652 | return PTR_ERR(remote); | |
653 | } | |
654 | } | |
655 | if (remote_arg->common_handle) { | |
eec028c9 AK |
656 | if (!kcov_check_handle(remote_arg->common_handle, |
657 | true, false, false)) { | |
5ff3b30a AK |
658 | spin_unlock_irqrestore(&kcov_remote_lock, |
659 | flags); | |
eec028c9 AK |
660 | kcov_disable(t, kcov); |
661 | return -EINVAL; | |
662 | } | |
663 | remote = kcov_remote_add(kcov, | |
664 | remote_arg->common_handle); | |
665 | if (IS_ERR(remote)) { | |
5ff3b30a AK |
666 | spin_unlock_irqrestore(&kcov_remote_lock, |
667 | flags); | |
eec028c9 AK |
668 | kcov_disable(t, kcov); |
669 | return PTR_ERR(remote); | |
670 | } | |
671 | t->kcov_handle = remote_arg->common_handle; | |
672 | } | |
5ff3b30a | 673 | spin_unlock_irqrestore(&kcov_remote_lock, flags); |
eec028c9 AK |
674 | /* Put either in kcov_task_exit() or in KCOV_DISABLE. */ |
675 | kcov_get(kcov); | |
676 | return 0; | |
5c9a8750 DV |
677 | default: |
678 | return -ENOTTY; | |
679 | } | |
680 | } | |
681 | ||
682 | static long kcov_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) | |
683 | { | |
684 | struct kcov *kcov; | |
685 | int res; | |
eec028c9 AK |
686 | struct kcov_remote_arg *remote_arg = NULL; |
687 | unsigned int remote_num_handles; | |
688 | unsigned long remote_arg_size; | |
17581aa1 | 689 | unsigned long size, flags; |
b3d7fe86 | 690 | void *area; |
eec028c9 | 691 | |
17581aa1 AN |
692 | kcov = filep->private_data; |
693 | switch (cmd) { | |
694 | case KCOV_INIT_TRACE: | |
695 | /* | |
696 | * Enable kcov in trace mode and setup buffer size. | |
697 | * Must happen before anything else. | |
698 | * | |
699 | * First check the size argument - it must be at least 2 | |
b3d7fe86 | 700 | * to hold the current position and one PC. |
17581aa1 AN |
701 | */ |
702 | size = arg; | |
703 | if (size < 2 || size > INT_MAX / sizeof(unsigned long)) | |
704 | return -EINVAL; | |
b3d7fe86 AN |
705 | area = vmalloc_user(size * sizeof(unsigned long)); |
706 | if (area == NULL) | |
707 | return -ENOMEM; | |
17581aa1 AN |
708 | spin_lock_irqsave(&kcov->lock, flags); |
709 | if (kcov->mode != KCOV_MODE_DISABLED) { | |
710 | spin_unlock_irqrestore(&kcov->lock, flags); | |
b3d7fe86 | 711 | vfree(area); |
17581aa1 AN |
712 | return -EBUSY; |
713 | } | |
b3d7fe86 | 714 | kcov->area = area; |
17581aa1 AN |
715 | kcov->size = size; |
716 | kcov->mode = KCOV_MODE_INIT; | |
717 | spin_unlock_irqrestore(&kcov->lock, flags); | |
718 | return 0; | |
719 | case KCOV_REMOTE_ENABLE: | |
eec028c9 AK |
720 | if (get_user(remote_num_handles, (unsigned __user *)(arg + |
721 | offsetof(struct kcov_remote_arg, num_handles)))) | |
722 | return -EFAULT; | |
723 | if (remote_num_handles > KCOV_REMOTE_MAX_HANDLES) | |
724 | return -EINVAL; | |
725 | remote_arg_size = struct_size(remote_arg, handles, | |
726 | remote_num_handles); | |
727 | remote_arg = memdup_user((void __user *)arg, remote_arg_size); | |
728 | if (IS_ERR(remote_arg)) | |
729 | return PTR_ERR(remote_arg); | |
730 | if (remote_arg->num_handles != remote_num_handles) { | |
731 | kfree(remote_arg); | |
732 | return -EINVAL; | |
733 | } | |
734 | arg = (unsigned long)remote_arg; | |
17581aa1 AN |
735 | fallthrough; |
736 | default: | |
737 | /* | |
738 | * All other commands can be normally executed under a spin lock, so we | |
739 | * obtain and release it here in order to simplify kcov_ioctl_locked(). | |
740 | */ | |
741 | spin_lock_irqsave(&kcov->lock, flags); | |
742 | res = kcov_ioctl_locked(kcov, cmd, arg); | |
743 | spin_unlock_irqrestore(&kcov->lock, flags); | |
744 | kfree(remote_arg); | |
745 | return res; | |
eec028c9 | 746 | } |
5c9a8750 DV |
747 | } |
748 | ||
749 | static const struct file_operations kcov_fops = { | |
750 | .open = kcov_open, | |
751 | .unlocked_ioctl = kcov_ioctl, | |
7483e5d4 | 752 | .compat_ioctl = kcov_ioctl, |
5c9a8750 DV |
753 | .mmap = kcov_mmap, |
754 | .release = kcov_close, | |
755 | }; | |
756 | ||
eec028c9 AK |
757 | /* |
758 | * kcov_remote_start() and kcov_remote_stop() can be used to annotate a section | |
5ff3b30a AK |
759 | * of code in a kernel background thread or in a softirq to allow kcov to be |
760 | * used to collect coverage from that part of code. | |
eec028c9 AK |
761 | * |
762 | * The handle argument of kcov_remote_start() identifies a code section that is | |
763 | * used for coverage collection. A userspace process passes this handle to | |
764 | * KCOV_REMOTE_ENABLE ioctl to make the used kcov device start collecting | |
765 | * coverage for the code section identified by this handle. | |
766 | * | |
767 | * The usage of these annotations in the kernel code is different depending on | |
768 | * the type of the kernel thread whose code is being annotated. | |
769 | * | |
770 | * For global kernel threads that are spawned in a limited number of instances | |
5ff3b30a AK |
771 | * (e.g. one USB hub_event() worker thread is spawned per USB HCD) and for |
772 | * softirqs, each instance must be assigned a unique 4-byte instance id. The | |
773 | * instance id is then combined with a 1-byte subsystem id to get a handle via | |
eec028c9 AK |
774 | * kcov_remote_handle(subsystem_id, instance_id). |
775 | * | |
776 | * For local kernel threads that are spawned from system calls handler when a | |
777 | * user interacts with some kernel interface (e.g. vhost workers), a handle is | |
778 | * passed from a userspace process as the common_handle field of the | |
779 | * kcov_remote_arg struct (note, that the user must generate a handle by using | |
780 | * kcov_remote_handle() with KCOV_SUBSYSTEM_COMMON as the subsystem id and an | |
781 | * arbitrary 4-byte non-zero number as the instance id). This common handle | |
782 | * then gets saved into the task_struct of the process that issued the | |
324cfb19 MG |
783 | * KCOV_REMOTE_ENABLE ioctl. When this process issues system calls that spawn |
784 | * kernel threads, the common handle must be retrieved via kcov_common_handle() | |
eec028c9 AK |
785 | * and passed to the spawned threads via custom annotations. Those kernel |
786 | * threads must in turn be annotated with kcov_remote_start(common_handle) and | |
787 | * kcov_remote_stop(). All of the threads that are spawned by the same process | |
788 | * obtain the same handle, hence the name "common". | |
789 | * | |
790 | * See Documentation/dev-tools/kcov.rst for more details. | |
791 | * | |
5ff3b30a | 792 | * Internally, kcov_remote_start() looks up the kcov device associated with the |
eec028c9 AK |
793 | * provided handle, allocates an area for coverage collection, and saves the |
794 | * pointers to kcov and area into the current task_struct to allow coverage to | |
3021e692 | 795 | * be collected via __sanitizer_cov_trace_pc(). |
eec028c9 AK |
796 | * In turns kcov_remote_stop() clears those pointers from task_struct to stop |
797 | * collecting coverage and copies all collected coverage into the kcov area. | |
798 | */ | |
5fe7042d AK |
799 | |
800 | static inline bool kcov_mode_enabled(unsigned int mode) | |
801 | { | |
802 | return (mode & ~KCOV_IN_CTXSW) != KCOV_MODE_DISABLED; | |
803 | } | |
804 | ||
fed79d05 | 805 | static void kcov_remote_softirq_start(struct task_struct *t) |
5ff3b30a AK |
806 | { |
807 | struct kcov_percpu_data *data = this_cpu_ptr(&kcov_percpu_data); | |
808 | unsigned int mode; | |
809 | ||
810 | mode = READ_ONCE(t->kcov_mode); | |
811 | barrier(); | |
812 | if (kcov_mode_enabled(mode)) { | |
813 | data->saved_mode = mode; | |
814 | data->saved_size = t->kcov_size; | |
815 | data->saved_area = t->kcov_area; | |
816 | data->saved_sequence = t->kcov_sequence; | |
817 | data->saved_kcov = t->kcov; | |
818 | kcov_stop(t); | |
819 | } | |
820 | } | |
821 | ||
fed79d05 | 822 | static void kcov_remote_softirq_stop(struct task_struct *t) |
5ff3b30a AK |
823 | { |
824 | struct kcov_percpu_data *data = this_cpu_ptr(&kcov_percpu_data); | |
825 | ||
826 | if (data->saved_kcov) { | |
827 | kcov_start(t, data->saved_kcov, data->saved_size, | |
828 | data->saved_area, data->saved_mode, | |
829 | data->saved_sequence); | |
830 | data->saved_mode = 0; | |
831 | data->saved_size = 0; | |
832 | data->saved_area = NULL; | |
833 | data->saved_sequence = 0; | |
834 | data->saved_kcov = NULL; | |
835 | } | |
836 | } | |
837 | ||
eec028c9 AK |
838 | void kcov_remote_start(u64 handle) |
839 | { | |
5fe7042d | 840 | struct task_struct *t = current; |
eec028c9 | 841 | struct kcov_remote *remote; |
67b3d3cc | 842 | struct kcov *kcov; |
5fe7042d | 843 | unsigned int mode; |
eec028c9 | 844 | void *area; |
eec028c9 | 845 | unsigned int size; |
eec028c9 | 846 | int sequence; |
5ff3b30a | 847 | unsigned long flags; |
eec028c9 AK |
848 | |
849 | if (WARN_ON(!kcov_check_handle(handle, true, true, true))) | |
850 | return; | |
5ff3b30a | 851 | if (!in_task() && !in_serving_softirq()) |
eec028c9 | 852 | return; |
5fe7042d | 853 | |
d5d2c51f | 854 | local_lock_irqsave(&kcov_percpu_data.lock, flags); |
5ff3b30a | 855 | |
eec028c9 | 856 | /* |
5ff3b30a AK |
857 | * Check that kcov_remote_start() is not called twice in background |
858 | * threads nor called by user tasks (with enabled kcov). | |
eec028c9 | 859 | */ |
5fe7042d | 860 | mode = READ_ONCE(t->kcov_mode); |
5ff3b30a | 861 | if (WARN_ON(in_task() && kcov_mode_enabled(mode))) { |
d5d2c51f | 862 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); |
eec028c9 | 863 | return; |
5ff3b30a AK |
864 | } |
865 | /* | |
866 | * Check that kcov_remote_start() is not called twice in softirqs. | |
867 | * Note, that kcov_remote_start() can be called from a softirq that | |
868 | * happened while collecting coverage from a background thread. | |
869 | */ | |
870 | if (WARN_ON(in_serving_softirq() && t->kcov_softirq)) { | |
d5d2c51f | 871 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); |
5ff3b30a AK |
872 | return; |
873 | } | |
eec028c9 AK |
874 | |
875 | spin_lock(&kcov_remote_lock); | |
876 | remote = kcov_remote_find(handle); | |
877 | if (!remote) { | |
d5d2c51f SAS |
878 | spin_unlock(&kcov_remote_lock); |
879 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); | |
eec028c9 AK |
880 | return; |
881 | } | |
5ff3b30a AK |
882 | kcov_debug("handle = %llx, context: %s\n", handle, |
883 | in_task() ? "task" : "softirq"); | |
67b3d3cc | 884 | kcov = remote->kcov; |
eec028c9 | 885 | /* Put in kcov_remote_stop(). */ |
67b3d3cc | 886 | kcov_get(kcov); |
eec028c9 AK |
887 | /* |
888 | * Read kcov fields before unlock to prevent races with | |
889 | * KCOV_DISABLE / kcov_remote_reset(). | |
890 | */ | |
67b3d3cc AK |
891 | mode = kcov->mode; |
892 | sequence = kcov->sequence; | |
5ff3b30a AK |
893 | if (in_task()) { |
894 | size = kcov->remote_size; | |
895 | area = kcov_remote_area_get(size); | |
896 | } else { | |
897 | size = CONFIG_KCOV_IRQ_AREA_SIZE; | |
898 | area = this_cpu_ptr(&kcov_percpu_data)->irq_area; | |
899 | } | |
22036abe | 900 | spin_unlock(&kcov_remote_lock); |
eec028c9 | 901 | |
5ff3b30a | 902 | /* Can only happen when in_task(). */ |
eec028c9 | 903 | if (!area) { |
d5d2c51f | 904 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); |
eec028c9 AK |
905 | area = vmalloc(size * sizeof(unsigned long)); |
906 | if (!area) { | |
67b3d3cc | 907 | kcov_put(kcov); |
eec028c9 AK |
908 | return; |
909 | } | |
d5d2c51f | 910 | local_lock_irqsave(&kcov_percpu_data.lock, flags); |
eec028c9 | 911 | } |
5ff3b30a | 912 | |
eec028c9 AK |
913 | /* Reset coverage size. */ |
914 | *(u64 *)area = 0; | |
915 | ||
5ff3b30a AK |
916 | if (in_serving_softirq()) { |
917 | kcov_remote_softirq_start(t); | |
918 | t->kcov_softirq = 1; | |
919 | } | |
76484b1c | 920 | kcov_start(t, kcov, size, area, mode, sequence); |
eec028c9 | 921 | |
d5d2c51f | 922 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); |
5ff3b30a | 923 | |
eec028c9 AK |
924 | } |
925 | EXPORT_SYMBOL(kcov_remote_start); | |
926 | ||
927 | static void kcov_move_area(enum kcov_mode mode, void *dst_area, | |
928 | unsigned int dst_area_size, void *src_area) | |
929 | { | |
930 | u64 word_size = sizeof(unsigned long); | |
931 | u64 count_size, entry_size_log; | |
932 | u64 dst_len, src_len; | |
933 | void *dst_entries, *src_entries; | |
934 | u64 dst_occupied, dst_free, bytes_to_move, entries_moved; | |
935 | ||
936 | kcov_debug("%px %u <= %px %lu\n", | |
937 | dst_area, dst_area_size, src_area, *(unsigned long *)src_area); | |
938 | ||
939 | switch (mode) { | |
940 | case KCOV_MODE_TRACE_PC: | |
941 | dst_len = READ_ONCE(*(unsigned long *)dst_area); | |
942 | src_len = *(unsigned long *)src_area; | |
943 | count_size = sizeof(unsigned long); | |
944 | entry_size_log = __ilog2_u64(sizeof(unsigned long)); | |
945 | break; | |
946 | case KCOV_MODE_TRACE_CMP: | |
947 | dst_len = READ_ONCE(*(u64 *)dst_area); | |
948 | src_len = *(u64 *)src_area; | |
949 | count_size = sizeof(u64); | |
950 | BUILD_BUG_ON(!is_power_of_2(KCOV_WORDS_PER_CMP)); | |
951 | entry_size_log = __ilog2_u64(sizeof(u64) * KCOV_WORDS_PER_CMP); | |
952 | break; | |
953 | default: | |
954 | WARN_ON(1); | |
955 | return; | |
956 | } | |
957 | ||
958 | /* As arm can't divide u64 integers use log of entry size. */ | |
959 | if (dst_len > ((dst_area_size * word_size - count_size) >> | |
960 | entry_size_log)) | |
961 | return; | |
962 | dst_occupied = count_size + (dst_len << entry_size_log); | |
963 | dst_free = dst_area_size * word_size - dst_occupied; | |
964 | bytes_to_move = min(dst_free, src_len << entry_size_log); | |
965 | dst_entries = dst_area + dst_occupied; | |
966 | src_entries = src_area + count_size; | |
967 | memcpy(dst_entries, src_entries, bytes_to_move); | |
968 | entries_moved = bytes_to_move >> entry_size_log; | |
969 | ||
970 | switch (mode) { | |
971 | case KCOV_MODE_TRACE_PC: | |
972 | WRITE_ONCE(*(unsigned long *)dst_area, dst_len + entries_moved); | |
973 | break; | |
974 | case KCOV_MODE_TRACE_CMP: | |
975 | WRITE_ONCE(*(u64 *)dst_area, dst_len + entries_moved); | |
976 | break; | |
977 | default: | |
978 | break; | |
979 | } | |
980 | } | |
981 | ||
982 | /* See the comment before kcov_remote_start() for usage details. */ | |
983 | void kcov_remote_stop(void) | |
984 | { | |
985 | struct task_struct *t = current; | |
5fe7042d AK |
986 | struct kcov *kcov; |
987 | unsigned int mode; | |
988 | void *area; | |
989 | unsigned int size; | |
990 | int sequence; | |
5ff3b30a AK |
991 | unsigned long flags; |
992 | ||
993 | if (!in_task() && !in_serving_softirq()) | |
994 | return; | |
995 | ||
d5d2c51f | 996 | local_lock_irqsave(&kcov_percpu_data.lock, flags); |
eec028c9 | 997 | |
5fe7042d AK |
998 | mode = READ_ONCE(t->kcov_mode); |
999 | barrier(); | |
5ff3b30a | 1000 | if (!kcov_mode_enabled(mode)) { |
d5d2c51f | 1001 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); |
eec028c9 | 1002 | return; |
5ff3b30a | 1003 | } |
3021e692 AK |
1004 | /* |
1005 | * When in softirq, check if the corresponding kcov_remote_start() | |
1006 | * actually found the remote handle and started collecting coverage. | |
1007 | */ | |
1008 | if (in_serving_softirq() && !t->kcov_softirq) { | |
d5d2c51f | 1009 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); |
3021e692 AK |
1010 | return; |
1011 | } | |
1012 | /* Make sure that kcov_softirq is only set when in softirq. */ | |
5ff3b30a | 1013 | if (WARN_ON(!in_serving_softirq() && t->kcov_softirq)) { |
d5d2c51f | 1014 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); |
5ff3b30a AK |
1015 | return; |
1016 | } | |
1017 | ||
3021e692 AK |
1018 | kcov = t->kcov; |
1019 | area = t->kcov_area; | |
1020 | size = t->kcov_size; | |
1021 | sequence = t->kcov_sequence; | |
1022 | ||
eec028c9 | 1023 | kcov_stop(t); |
5ff3b30a AK |
1024 | if (in_serving_softirq()) { |
1025 | t->kcov_softirq = 0; | |
1026 | kcov_remote_softirq_stop(t); | |
1027 | } | |
eec028c9 AK |
1028 | |
1029 | spin_lock(&kcov->lock); | |
1030 | /* | |
1031 | * KCOV_DISABLE could have been called between kcov_remote_start() | |
5ff3b30a | 1032 | * and kcov_remote_stop(), hence the sequence check. |
eec028c9 | 1033 | */ |
eec028c9 AK |
1034 | if (sequence == kcov->sequence && kcov->remote) |
1035 | kcov_move_area(kcov->mode, kcov->area, kcov->size, area); | |
1036 | spin_unlock(&kcov->lock); | |
1037 | ||
5ff3b30a AK |
1038 | if (in_task()) { |
1039 | spin_lock(&kcov_remote_lock); | |
1040 | kcov_remote_area_put(area, size); | |
1041 | spin_unlock(&kcov_remote_lock); | |
1042 | } | |
eec028c9 | 1043 | |
d5d2c51f | 1044 | local_unlock_irqrestore(&kcov_percpu_data.lock, flags); |
5ff3b30a AK |
1045 | |
1046 | /* Get in kcov_remote_start(). */ | |
eec028c9 AK |
1047 | kcov_put(kcov); |
1048 | } | |
1049 | EXPORT_SYMBOL(kcov_remote_stop); | |
1050 | ||
1051 | /* See the comment before kcov_remote_start() for usage details. */ | |
1052 | u64 kcov_common_handle(void) | |
1053 | { | |
b08e84da AN |
1054 | if (!in_task()) |
1055 | return 0; | |
eec028c9 AK |
1056 | return current->kcov_handle; |
1057 | } | |
1058 | EXPORT_SYMBOL(kcov_common_handle); | |
1059 | ||
5c9a8750 DV |
1060 | static int __init kcov_init(void) |
1061 | { | |
5ff3b30a AK |
1062 | int cpu; |
1063 | ||
1064 | for_each_possible_cpu(cpu) { | |
741ddd45 SAS |
1065 | void *area = vmalloc_node(CONFIG_KCOV_IRQ_AREA_SIZE * |
1066 | sizeof(unsigned long), cpu_to_node(cpu)); | |
5ff3b30a AK |
1067 | if (!area) |
1068 | return -ENOMEM; | |
1069 | per_cpu_ptr(&kcov_percpu_data, cpu)->irq_area = area; | |
1070 | } | |
1071 | ||
df4565f9 NS |
1072 | /* |
1073 | * The kcov debugfs file won't ever get removed and thus, | |
1074 | * there is no need to protect it against removal races. The | |
1075 | * use of debugfs_create_file_unsafe() is actually safe here. | |
1076 | */ | |
ec9672d5 GKH |
1077 | debugfs_create_file_unsafe("kcov", 0600, NULL, NULL, &kcov_fops); |
1078 | ||
5c9a8750 DV |
1079 | return 0; |
1080 | } | |
1081 | ||
1082 | device_initcall(kcov_init); |