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