Commit | Line | Data |
---|---|---|
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 | ||
89 | /* Must be called with kcov_remote_lock locked. */ | |
90 | static struct kcov_remote *kcov_remote_find(u64 handle) | |
91 | { | |
92 | struct kcov_remote *remote; | |
93 | ||
94 | hash_for_each_possible(kcov_remote_map, remote, hnode, handle) { | |
95 | if (remote->handle == handle) | |
96 | return remote; | |
97 | } | |
98 | return NULL; | |
99 | } | |
100 | ||
3c61df38 | 101 | /* Must be called with kcov_remote_lock locked. */ |
eec028c9 AK |
102 | static struct kcov_remote *kcov_remote_add(struct kcov *kcov, u64 handle) |
103 | { | |
104 | struct kcov_remote *remote; | |
105 | ||
106 | if (kcov_remote_find(handle)) | |
107 | return ERR_PTR(-EEXIST); | |
108 | remote = kmalloc(sizeof(*remote), GFP_ATOMIC); | |
109 | if (!remote) | |
110 | return ERR_PTR(-ENOMEM); | |
111 | remote->handle = handle; | |
112 | remote->kcov = kcov; | |
113 | hash_add(kcov_remote_map, &remote->hnode, handle); | |
114 | return remote; | |
115 | } | |
116 | ||
117 | /* Must be called with kcov_remote_lock locked. */ | |
118 | static struct kcov_remote_area *kcov_remote_area_get(unsigned int size) | |
119 | { | |
120 | struct kcov_remote_area *area; | |
121 | struct list_head *pos; | |
122 | ||
eec028c9 AK |
123 | list_for_each(pos, &kcov_remote_areas) { |
124 | area = list_entry(pos, struct kcov_remote_area, list); | |
125 | if (area->size == size) { | |
126 | list_del(&area->list); | |
eec028c9 AK |
127 | return area; |
128 | } | |
129 | } | |
eec028c9 AK |
130 | return NULL; |
131 | } | |
132 | ||
133 | /* Must be called with kcov_remote_lock locked. */ | |
134 | static void kcov_remote_area_put(struct kcov_remote_area *area, | |
135 | unsigned int size) | |
136 | { | |
eec028c9 AK |
137 | INIT_LIST_HEAD(&area->list); |
138 | area->size = size; | |
139 | list_add(&area->list, &kcov_remote_areas); | |
140 | } | |
141 | ||
903e8ff8 | 142 | static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t) |
5c9a8750 | 143 | { |
0ed557aa | 144 | unsigned int mode; |
5c9a8750 | 145 | |
5c9a8750 DV |
146 | /* |
147 | * We are interested in code coverage as a function of a syscall inputs, | |
148 | * so we ignore code executed in interrupts. | |
149 | */ | |
fcf4edac | 150 | if (!in_task()) |
ded97d2c | 151 | return false; |
5c9a8750 | 152 | mode = READ_ONCE(t->kcov_mode); |
ded97d2c VC |
153 | /* |
154 | * There is some code that runs in interrupts but for which | |
155 | * in_interrupt() returns false (e.g. preempt_schedule_irq()). | |
156 | * READ_ONCE()/barrier() effectively provides load-acquire wrt | |
157 | * interrupts, there are paired barrier()/WRITE_ONCE() in | |
eec028c9 | 158 | * kcov_start(). |
ded97d2c VC |
159 | */ |
160 | barrier(); | |
161 | return mode == needed_mode; | |
162 | } | |
4983f0ab | 163 | |
903e8ff8 | 164 | static notrace unsigned long canonicalize_ip(unsigned long ip) |
ded97d2c | 165 | { |
4983f0ab | 166 | #ifdef CONFIG_RANDOMIZE_BASE |
ded97d2c | 167 | ip -= kaslr_offset(); |
4983f0ab | 168 | #endif |
ded97d2c VC |
169 | return ip; |
170 | } | |
5c9a8750 | 171 | |
ded97d2c VC |
172 | /* |
173 | * Entry point from instrumented code. | |
174 | * This is called once per basic-block/edge. | |
175 | */ | |
176 | void notrace __sanitizer_cov_trace_pc(void) | |
177 | { | |
178 | struct task_struct *t; | |
179 | unsigned long *area; | |
180 | unsigned long ip = canonicalize_ip(_RET_IP_); | |
181 | unsigned long pos; | |
182 | ||
183 | t = current; | |
184 | if (!check_kcov_mode(KCOV_MODE_TRACE_PC, t)) | |
185 | return; | |
186 | ||
187 | area = t->kcov_area; | |
188 | /* The first 64-bit word is the number of subsequent PCs. */ | |
189 | pos = READ_ONCE(area[0]) + 1; | |
190 | if (likely(pos < t->kcov_size)) { | |
191 | area[pos] = ip; | |
192 | WRITE_ONCE(area[0], pos); | |
5c9a8750 DV |
193 | } |
194 | } | |
195 | EXPORT_SYMBOL(__sanitizer_cov_trace_pc); | |
196 | ||
ded97d2c | 197 | #ifdef CONFIG_KCOV_ENABLE_COMPARISONS |
63472443 | 198 | static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip) |
ded97d2c VC |
199 | { |
200 | struct task_struct *t; | |
201 | u64 *area; | |
202 | u64 count, start_index, end_pos, max_pos; | |
203 | ||
204 | t = current; | |
205 | if (!check_kcov_mode(KCOV_MODE_TRACE_CMP, t)) | |
206 | return; | |
207 | ||
208 | ip = canonicalize_ip(ip); | |
209 | ||
210 | /* | |
211 | * We write all comparison arguments and types as u64. | |
212 | * The buffer was allocated for t->kcov_size unsigned longs. | |
213 | */ | |
214 | area = (u64 *)t->kcov_area; | |
215 | max_pos = t->kcov_size * sizeof(unsigned long); | |
216 | ||
217 | count = READ_ONCE(area[0]); | |
218 | ||
219 | /* Every record is KCOV_WORDS_PER_CMP 64-bit words. */ | |
220 | start_index = 1 + count * KCOV_WORDS_PER_CMP; | |
221 | end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64); | |
222 | if (likely(end_pos <= max_pos)) { | |
223 | area[start_index] = type; | |
224 | area[start_index + 1] = arg1; | |
225 | area[start_index + 2] = arg2; | |
226 | area[start_index + 3] = ip; | |
227 | WRITE_ONCE(area[0], count + 1); | |
228 | } | |
229 | } | |
230 | ||
231 | void notrace __sanitizer_cov_trace_cmp1(u8 arg1, u8 arg2) | |
232 | { | |
233 | write_comp_data(KCOV_CMP_SIZE(0), arg1, arg2, _RET_IP_); | |
234 | } | |
235 | EXPORT_SYMBOL(__sanitizer_cov_trace_cmp1); | |
236 | ||
237 | void notrace __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2) | |
238 | { | |
239 | write_comp_data(KCOV_CMP_SIZE(1), arg1, arg2, _RET_IP_); | |
240 | } | |
241 | EXPORT_SYMBOL(__sanitizer_cov_trace_cmp2); | |
242 | ||
689d77f0 | 243 | void notrace __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2) |
ded97d2c VC |
244 | { |
245 | write_comp_data(KCOV_CMP_SIZE(2), arg1, arg2, _RET_IP_); | |
246 | } | |
247 | EXPORT_SYMBOL(__sanitizer_cov_trace_cmp4); | |
248 | ||
249 | void notrace __sanitizer_cov_trace_cmp8(u64 arg1, u64 arg2) | |
250 | { | |
251 | write_comp_data(KCOV_CMP_SIZE(3), arg1, arg2, _RET_IP_); | |
252 | } | |
253 | EXPORT_SYMBOL(__sanitizer_cov_trace_cmp8); | |
254 | ||
255 | void notrace __sanitizer_cov_trace_const_cmp1(u8 arg1, u8 arg2) | |
256 | { | |
257 | write_comp_data(KCOV_CMP_SIZE(0) | KCOV_CMP_CONST, arg1, arg2, | |
258 | _RET_IP_); | |
259 | } | |
260 | EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp1); | |
261 | ||
262 | void notrace __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2) | |
263 | { | |
264 | write_comp_data(KCOV_CMP_SIZE(1) | KCOV_CMP_CONST, arg1, arg2, | |
265 | _RET_IP_); | |
266 | } | |
267 | EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp2); | |
268 | ||
689d77f0 | 269 | void notrace __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2) |
ded97d2c VC |
270 | { |
271 | write_comp_data(KCOV_CMP_SIZE(2) | KCOV_CMP_CONST, arg1, arg2, | |
272 | _RET_IP_); | |
273 | } | |
274 | EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp4); | |
275 | ||
276 | void notrace __sanitizer_cov_trace_const_cmp8(u64 arg1, u64 arg2) | |
277 | { | |
278 | write_comp_data(KCOV_CMP_SIZE(3) | KCOV_CMP_CONST, arg1, arg2, | |
279 | _RET_IP_); | |
280 | } | |
281 | EXPORT_SYMBOL(__sanitizer_cov_trace_const_cmp8); | |
282 | ||
283 | void notrace __sanitizer_cov_trace_switch(u64 val, u64 *cases) | |
284 | { | |
285 | u64 i; | |
286 | u64 count = cases[0]; | |
287 | u64 size = cases[1]; | |
288 | u64 type = KCOV_CMP_CONST; | |
289 | ||
290 | switch (size) { | |
291 | case 8: | |
292 | type |= KCOV_CMP_SIZE(0); | |
293 | break; | |
294 | case 16: | |
295 | type |= KCOV_CMP_SIZE(1); | |
296 | break; | |
297 | case 32: | |
298 | type |= KCOV_CMP_SIZE(2); | |
299 | break; | |
300 | case 64: | |
301 | type |= KCOV_CMP_SIZE(3); | |
302 | break; | |
303 | default: | |
304 | return; | |
305 | } | |
306 | for (i = 0; i < count; i++) | |
307 | write_comp_data(type, cases[i + 2], val, _RET_IP_); | |
308 | } | |
309 | EXPORT_SYMBOL(__sanitizer_cov_trace_switch); | |
310 | #endif /* ifdef CONFIG_KCOV_ENABLE_COMPARISONS */ | |
311 | ||
eec028c9 AK |
312 | static void kcov_start(struct task_struct *t, unsigned int size, |
313 | void *area, enum kcov_mode mode, int sequence) | |
314 | { | |
315 | kcov_debug("t = %px, size = %u, area = %px\n", t, size, area); | |
316 | /* Cache in task struct for performance. */ | |
317 | t->kcov_size = size; | |
318 | t->kcov_area = area; | |
319 | /* See comment in check_kcov_mode(). */ | |
320 | barrier(); | |
321 | WRITE_ONCE(t->kcov_mode, mode); | |
322 | t->kcov_sequence = sequence; | |
323 | } | |
324 | ||
325 | static void kcov_stop(struct task_struct *t) | |
326 | { | |
327 | WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED); | |
328 | barrier(); | |
329 | t->kcov_size = 0; | |
330 | t->kcov_area = NULL; | |
331 | } | |
332 | ||
333 | static void kcov_task_reset(struct task_struct *t) | |
334 | { | |
335 | kcov_stop(t); | |
336 | t->kcov = NULL; | |
337 | t->kcov_sequence = 0; | |
338 | t->kcov_handle = 0; | |
339 | } | |
340 | ||
341 | void kcov_task_init(struct task_struct *t) | |
342 | { | |
343 | kcov_task_reset(t); | |
344 | t->kcov_handle = current->kcov_handle; | |
345 | } | |
346 | ||
347 | static void kcov_reset(struct kcov *kcov) | |
348 | { | |
349 | kcov->t = NULL; | |
350 | kcov->mode = KCOV_MODE_INIT; | |
351 | kcov->remote = false; | |
352 | kcov->remote_size = 0; | |
353 | kcov->sequence++; | |
354 | } | |
355 | ||
356 | static void kcov_remote_reset(struct kcov *kcov) | |
357 | { | |
358 | int bkt; | |
359 | struct kcov_remote *remote; | |
360 | struct hlist_node *tmp; | |
361 | ||
362 | spin_lock(&kcov_remote_lock); | |
363 | hash_for_each_safe(kcov_remote_map, bkt, tmp, remote, hnode) { | |
364 | if (remote->kcov != kcov) | |
365 | continue; | |
eec028c9 AK |
366 | hash_del(&remote->hnode); |
367 | kfree(remote); | |
368 | } | |
369 | /* Do reset before unlock to prevent races with kcov_remote_start(). */ | |
370 | kcov_reset(kcov); | |
371 | spin_unlock(&kcov_remote_lock); | |
372 | } | |
373 | ||
374 | static void kcov_disable(struct task_struct *t, struct kcov *kcov) | |
375 | { | |
376 | kcov_task_reset(t); | |
377 | if (kcov->remote) | |
378 | kcov_remote_reset(kcov); | |
379 | else | |
380 | kcov_reset(kcov); | |
381 | } | |
382 | ||
5c9a8750 DV |
383 | static void kcov_get(struct kcov *kcov) |
384 | { | |
39e07cb6 | 385 | refcount_inc(&kcov->refcount); |
5c9a8750 DV |
386 | } |
387 | ||
388 | static void kcov_put(struct kcov *kcov) | |
389 | { | |
39e07cb6 | 390 | if (refcount_dec_and_test(&kcov->refcount)) { |
eec028c9 | 391 | kcov_remote_reset(kcov); |
5c9a8750 DV |
392 | vfree(kcov->area); |
393 | kfree(kcov); | |
394 | } | |
395 | } | |
396 | ||
5c9a8750 DV |
397 | void kcov_task_exit(struct task_struct *t) |
398 | { | |
399 | struct kcov *kcov; | |
400 | ||
401 | kcov = t->kcov; | |
402 | if (kcov == NULL) | |
403 | return; | |
eec028c9 | 404 | |
5c9a8750 | 405 | spin_lock(&kcov->lock); |
eec028c9 AK |
406 | kcov_debug("t = %px, kcov->t = %px\n", t, kcov->t); |
407 | /* | |
408 | * For KCOV_ENABLE devices we want to make sure that t->kcov->t == t, | |
409 | * which comes down to: | |
410 | * WARN_ON(!kcov->remote && kcov->t != t); | |
411 | * | |
412 | * For KCOV_REMOTE_ENABLE devices, the exiting task is either: | |
413 | * 2. A remote task between kcov_remote_start() and kcov_remote_stop(). | |
414 | * In this case we should print a warning right away, since a task | |
415 | * shouldn't be exiting when it's in a kcov coverage collection | |
416 | * section. Here t points to the task that is collecting remote | |
417 | * coverage, and t->kcov->t points to the thread that created the | |
418 | * kcov device. Which means that to detect this case we need to | |
419 | * check that t != t->kcov->t, and this gives us the following: | |
420 | * WARN_ON(kcov->remote && kcov->t != t); | |
421 | * | |
422 | * 2. The task that created kcov exiting without calling KCOV_DISABLE, | |
423 | * and then again we can make sure that t->kcov->t == t: | |
424 | * WARN_ON(kcov->remote && kcov->t != t); | |
425 | * | |
426 | * By combining all three checks into one we get: | |
427 | */ | |
5c9a8750 DV |
428 | if (WARN_ON(kcov->t != t)) { |
429 | spin_unlock(&kcov->lock); | |
430 | return; | |
431 | } | |
432 | /* Just to not leave dangling references behind. */ | |
eec028c9 | 433 | kcov_disable(t, kcov); |
5c9a8750 DV |
434 | spin_unlock(&kcov->lock); |
435 | kcov_put(kcov); | |
436 | } | |
437 | ||
438 | static int kcov_mmap(struct file *filep, struct vm_area_struct *vma) | |
439 | { | |
440 | int res = 0; | |
441 | void *area; | |
442 | struct kcov *kcov = vma->vm_file->private_data; | |
443 | unsigned long size, off; | |
444 | struct page *page; | |
445 | ||
446 | area = vmalloc_user(vma->vm_end - vma->vm_start); | |
447 | if (!area) | |
448 | return -ENOMEM; | |
449 | ||
450 | spin_lock(&kcov->lock); | |
451 | size = kcov->size * sizeof(unsigned long); | |
ded97d2c | 452 | if (kcov->mode != KCOV_MODE_INIT || vma->vm_pgoff != 0 || |
5c9a8750 DV |
453 | vma->vm_end - vma->vm_start != size) { |
454 | res = -EINVAL; | |
455 | goto exit; | |
456 | } | |
457 | if (!kcov->area) { | |
458 | kcov->area = area; | |
459 | vma->vm_flags |= VM_DONTEXPAND; | |
460 | spin_unlock(&kcov->lock); | |
461 | for (off = 0; off < size; off += PAGE_SIZE) { | |
462 | page = vmalloc_to_page(kcov->area + off); | |
463 | if (vm_insert_page(vma, vma->vm_start + off, page)) | |
464 | WARN_ONCE(1, "vm_insert_page() failed"); | |
465 | } | |
466 | return 0; | |
467 | } | |
468 | exit: | |
469 | spin_unlock(&kcov->lock); | |
470 | vfree(area); | |
471 | return res; | |
472 | } | |
473 | ||
474 | static int kcov_open(struct inode *inode, struct file *filep) | |
475 | { | |
476 | struct kcov *kcov; | |
477 | ||
478 | kcov = kzalloc(sizeof(*kcov), GFP_KERNEL); | |
479 | if (!kcov) | |
480 | return -ENOMEM; | |
ded97d2c | 481 | kcov->mode = KCOV_MODE_DISABLED; |
eec028c9 | 482 | kcov->sequence = 1; |
39e07cb6 | 483 | refcount_set(&kcov->refcount, 1); |
5c9a8750 DV |
484 | spin_lock_init(&kcov->lock); |
485 | filep->private_data = kcov; | |
486 | return nonseekable_open(inode, filep); | |
487 | } | |
488 | ||
489 | static int kcov_close(struct inode *inode, struct file *filep) | |
490 | { | |
491 | kcov_put(filep->private_data); | |
492 | return 0; | |
493 | } | |
494 | ||
eec028c9 AK |
495 | static int kcov_get_mode(unsigned long arg) |
496 | { | |
497 | if (arg == KCOV_TRACE_PC) | |
498 | return KCOV_MODE_TRACE_PC; | |
499 | else if (arg == KCOV_TRACE_CMP) | |
500 | #ifdef CONFIG_KCOV_ENABLE_COMPARISONS | |
501 | return KCOV_MODE_TRACE_CMP; | |
502 | #else | |
503 | return -ENOTSUPP; | |
504 | #endif | |
505 | else | |
506 | return -EINVAL; | |
507 | } | |
508 | ||
dc55daff MR |
509 | /* |
510 | * Fault in a lazily-faulted vmalloc area before it can be used by | |
511 | * __santizer_cov_trace_pc(), to avoid recursion issues if any code on the | |
512 | * vmalloc fault handling path is instrumented. | |
513 | */ | |
514 | static void kcov_fault_in_area(struct kcov *kcov) | |
515 | { | |
516 | unsigned long stride = PAGE_SIZE / sizeof(unsigned long); | |
517 | unsigned long *area = kcov->area; | |
518 | unsigned long offset; | |
519 | ||
520 | for (offset = 0; offset < kcov->size; offset += stride) | |
521 | READ_ONCE(area[offset]); | |
522 | } | |
523 | ||
eec028c9 AK |
524 | static inline bool kcov_check_handle(u64 handle, bool common_valid, |
525 | bool uncommon_valid, bool zero_valid) | |
526 | { | |
527 | if (handle & ~(KCOV_SUBSYSTEM_MASK | KCOV_INSTANCE_MASK)) | |
528 | return false; | |
529 | switch (handle & KCOV_SUBSYSTEM_MASK) { | |
530 | case KCOV_SUBSYSTEM_COMMON: | |
531 | return (handle & KCOV_INSTANCE_MASK) ? | |
532 | common_valid : zero_valid; | |
533 | case KCOV_SUBSYSTEM_USB: | |
534 | return uncommon_valid; | |
535 | default: | |
536 | return false; | |
537 | } | |
538 | return false; | |
539 | } | |
540 | ||
5c9a8750 DV |
541 | static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, |
542 | unsigned long arg) | |
543 | { | |
544 | struct task_struct *t; | |
545 | unsigned long size, unused; | |
eec028c9 AK |
546 | int mode, i; |
547 | struct kcov_remote_arg *remote_arg; | |
548 | struct kcov_remote *remote; | |
5c9a8750 DV |
549 | |
550 | switch (cmd) { | |
551 | case KCOV_INIT_TRACE: | |
552 | /* | |
553 | * Enable kcov in trace mode and setup buffer size. | |
554 | * Must happen before anything else. | |
555 | */ | |
556 | if (kcov->mode != KCOV_MODE_DISABLED) | |
557 | return -EBUSY; | |
558 | /* | |
559 | * Size must be at least 2 to hold current position and one PC. | |
560 | * Later we allocate size * sizeof(unsigned long) memory, | |
561 | * that must not overflow. | |
562 | */ | |
563 | size = arg; | |
564 | if (size < 2 || size > INT_MAX / sizeof(unsigned long)) | |
565 | return -EINVAL; | |
566 | kcov->size = size; | |
ded97d2c | 567 | kcov->mode = KCOV_MODE_INIT; |
5c9a8750 DV |
568 | return 0; |
569 | case KCOV_ENABLE: | |
570 | /* | |
571 | * Enable coverage for the current task. | |
572 | * At this point user must have been enabled trace mode, | |
573 | * and mmapped the file. Coverage collection is disabled only | |
574 | * at task exit or voluntary by KCOV_DISABLE. After that it can | |
575 | * be enabled for another task. | |
576 | */ | |
ded97d2c | 577 | if (kcov->mode != KCOV_MODE_INIT || !kcov->area) |
5c9a8750 | 578 | return -EINVAL; |
a77660d2 DV |
579 | t = current; |
580 | if (kcov->t != NULL || t->kcov != NULL) | |
5c9a8750 | 581 | return -EBUSY; |
eec028c9 AK |
582 | mode = kcov_get_mode(arg); |
583 | if (mode < 0) | |
584 | return mode; | |
dc55daff | 585 | kcov_fault_in_area(kcov); |
eec028c9 AK |
586 | kcov->mode = mode; |
587 | kcov_start(t, kcov->size, kcov->area, kcov->mode, | |
588 | kcov->sequence); | |
5c9a8750 DV |
589 | t->kcov = kcov; |
590 | kcov->t = t; | |
eec028c9 | 591 | /* Put either in kcov_task_exit() or in KCOV_DISABLE. */ |
5c9a8750 DV |
592 | kcov_get(kcov); |
593 | return 0; | |
594 | case KCOV_DISABLE: | |
595 | /* Disable coverage for the current task. */ | |
596 | unused = arg; | |
597 | if (unused != 0 || current->kcov != kcov) | |
598 | return -EINVAL; | |
599 | t = current; | |
600 | if (WARN_ON(kcov->t != t)) | |
601 | return -EINVAL; | |
eec028c9 | 602 | kcov_disable(t, kcov); |
5c9a8750 DV |
603 | kcov_put(kcov); |
604 | return 0; | |
eec028c9 | 605 | case KCOV_REMOTE_ENABLE: |
eec028c9 AK |
606 | if (kcov->mode != KCOV_MODE_INIT || !kcov->area) |
607 | return -EINVAL; | |
608 | t = current; | |
609 | if (kcov->t != NULL || t->kcov != NULL) | |
610 | return -EBUSY; | |
611 | remote_arg = (struct kcov_remote_arg *)arg; | |
612 | mode = kcov_get_mode(remote_arg->trace_mode); | |
613 | if (mode < 0) | |
614 | return mode; | |
615 | if (remote_arg->area_size > LONG_MAX / sizeof(unsigned long)) | |
616 | return -EINVAL; | |
617 | kcov->mode = mode; | |
618 | t->kcov = kcov; | |
619 | kcov->t = t; | |
620 | kcov->remote = true; | |
621 | kcov->remote_size = remote_arg->area_size; | |
622 | spin_lock(&kcov_remote_lock); | |
623 | for (i = 0; i < remote_arg->num_handles; i++) { | |
eec028c9 AK |
624 | if (!kcov_check_handle(remote_arg->handles[i], |
625 | false, true, false)) { | |
626 | spin_unlock(&kcov_remote_lock); | |
627 | kcov_disable(t, kcov); | |
628 | return -EINVAL; | |
629 | } | |
630 | remote = kcov_remote_add(kcov, remote_arg->handles[i]); | |
631 | if (IS_ERR(remote)) { | |
632 | spin_unlock(&kcov_remote_lock); | |
633 | kcov_disable(t, kcov); | |
634 | return PTR_ERR(remote); | |
635 | } | |
636 | } | |
637 | if (remote_arg->common_handle) { | |
eec028c9 AK |
638 | if (!kcov_check_handle(remote_arg->common_handle, |
639 | true, false, false)) { | |
640 | spin_unlock(&kcov_remote_lock); | |
641 | kcov_disable(t, kcov); | |
642 | return -EINVAL; | |
643 | } | |
644 | remote = kcov_remote_add(kcov, | |
645 | remote_arg->common_handle); | |
646 | if (IS_ERR(remote)) { | |
647 | spin_unlock(&kcov_remote_lock); | |
648 | kcov_disable(t, kcov); | |
649 | return PTR_ERR(remote); | |
650 | } | |
651 | t->kcov_handle = remote_arg->common_handle; | |
652 | } | |
653 | spin_unlock(&kcov_remote_lock); | |
654 | /* Put either in kcov_task_exit() or in KCOV_DISABLE. */ | |
655 | kcov_get(kcov); | |
656 | return 0; | |
5c9a8750 DV |
657 | default: |
658 | return -ENOTTY; | |
659 | } | |
660 | } | |
661 | ||
662 | static long kcov_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) | |
663 | { | |
664 | struct kcov *kcov; | |
665 | int res; | |
eec028c9 AK |
666 | struct kcov_remote_arg *remote_arg = NULL; |
667 | unsigned int remote_num_handles; | |
668 | unsigned long remote_arg_size; | |
669 | ||
670 | if (cmd == KCOV_REMOTE_ENABLE) { | |
671 | if (get_user(remote_num_handles, (unsigned __user *)(arg + | |
672 | offsetof(struct kcov_remote_arg, num_handles)))) | |
673 | return -EFAULT; | |
674 | if (remote_num_handles > KCOV_REMOTE_MAX_HANDLES) | |
675 | return -EINVAL; | |
676 | remote_arg_size = struct_size(remote_arg, handles, | |
677 | remote_num_handles); | |
678 | remote_arg = memdup_user((void __user *)arg, remote_arg_size); | |
679 | if (IS_ERR(remote_arg)) | |
680 | return PTR_ERR(remote_arg); | |
681 | if (remote_arg->num_handles != remote_num_handles) { | |
682 | kfree(remote_arg); | |
683 | return -EINVAL; | |
684 | } | |
685 | arg = (unsigned long)remote_arg; | |
686 | } | |
5c9a8750 DV |
687 | |
688 | kcov = filep->private_data; | |
689 | spin_lock(&kcov->lock); | |
690 | res = kcov_ioctl_locked(kcov, cmd, arg); | |
691 | spin_unlock(&kcov->lock); | |
eec028c9 AK |
692 | |
693 | kfree(remote_arg); | |
694 | ||
5c9a8750 DV |
695 | return res; |
696 | } | |
697 | ||
698 | static const struct file_operations kcov_fops = { | |
699 | .open = kcov_open, | |
700 | .unlocked_ioctl = kcov_ioctl, | |
7483e5d4 | 701 | .compat_ioctl = kcov_ioctl, |
5c9a8750 DV |
702 | .mmap = kcov_mmap, |
703 | .release = kcov_close, | |
704 | }; | |
705 | ||
eec028c9 AK |
706 | /* |
707 | * kcov_remote_start() and kcov_remote_stop() can be used to annotate a section | |
708 | * of code in a kernel background thread to allow kcov to be used to collect | |
709 | * coverage from that part of code. | |
710 | * | |
711 | * The handle argument of kcov_remote_start() identifies a code section that is | |
712 | * used for coverage collection. A userspace process passes this handle to | |
713 | * KCOV_REMOTE_ENABLE ioctl to make the used kcov device start collecting | |
714 | * coverage for the code section identified by this handle. | |
715 | * | |
716 | * The usage of these annotations in the kernel code is different depending on | |
717 | * the type of the kernel thread whose code is being annotated. | |
718 | * | |
719 | * For global kernel threads that are spawned in a limited number of instances | |
720 | * (e.g. one USB hub_event() worker thread is spawned per USB HCD), each | |
721 | * instance must be assigned a unique 4-byte instance id. The instance id is | |
722 | * then combined with a 1-byte subsystem id to get a handle via | |
723 | * kcov_remote_handle(subsystem_id, instance_id). | |
724 | * | |
725 | * For local kernel threads that are spawned from system calls handler when a | |
726 | * user interacts with some kernel interface (e.g. vhost workers), a handle is | |
727 | * passed from a userspace process as the common_handle field of the | |
728 | * kcov_remote_arg struct (note, that the user must generate a handle by using | |
729 | * kcov_remote_handle() with KCOV_SUBSYSTEM_COMMON as the subsystem id and an | |
730 | * arbitrary 4-byte non-zero number as the instance id). This common handle | |
731 | * then gets saved into the task_struct of the process that issued the | |
324cfb19 MG |
732 | * KCOV_REMOTE_ENABLE ioctl. When this process issues system calls that spawn |
733 | * kernel threads, the common handle must be retrieved via kcov_common_handle() | |
eec028c9 AK |
734 | * and passed to the spawned threads via custom annotations. Those kernel |
735 | * threads must in turn be annotated with kcov_remote_start(common_handle) and | |
736 | * kcov_remote_stop(). All of the threads that are spawned by the same process | |
737 | * obtain the same handle, hence the name "common". | |
738 | * | |
739 | * See Documentation/dev-tools/kcov.rst for more details. | |
740 | * | |
741 | * Internally, this function looks up the kcov device associated with the | |
742 | * provided handle, allocates an area for coverage collection, and saves the | |
743 | * pointers to kcov and area into the current task_struct to allow coverage to | |
744 | * be collected via __sanitizer_cov_trace_pc() | |
745 | * In turns kcov_remote_stop() clears those pointers from task_struct to stop | |
746 | * collecting coverage and copies all collected coverage into the kcov area. | |
747 | */ | |
748 | void kcov_remote_start(u64 handle) | |
749 | { | |
750 | struct kcov_remote *remote; | |
67b3d3cc | 751 | struct kcov *kcov; |
eec028c9 AK |
752 | void *area; |
753 | struct task_struct *t; | |
754 | unsigned int size; | |
755 | enum kcov_mode mode; | |
756 | int sequence; | |
757 | ||
758 | if (WARN_ON(!kcov_check_handle(handle, true, true, true))) | |
759 | return; | |
760 | if (WARN_ON(!in_task())) | |
761 | return; | |
762 | t = current; | |
763 | /* | |
764 | * Check that kcov_remote_start is not called twice | |
765 | * nor called by user tasks (with enabled kcov). | |
766 | */ | |
767 | if (WARN_ON(t->kcov)) | |
768 | return; | |
769 | ||
770 | kcov_debug("handle = %llx\n", handle); | |
771 | ||
772 | spin_lock(&kcov_remote_lock); | |
773 | remote = kcov_remote_find(handle); | |
774 | if (!remote) { | |
eec028c9 AK |
775 | spin_unlock(&kcov_remote_lock); |
776 | return; | |
777 | } | |
67b3d3cc | 778 | kcov = remote->kcov; |
eec028c9 | 779 | /* Put in kcov_remote_stop(). */ |
67b3d3cc AK |
780 | kcov_get(kcov); |
781 | t->kcov = kcov; | |
eec028c9 AK |
782 | /* |
783 | * Read kcov fields before unlock to prevent races with | |
784 | * KCOV_DISABLE / kcov_remote_reset(). | |
785 | */ | |
67b3d3cc AK |
786 | size = kcov->remote_size; |
787 | mode = kcov->mode; | |
788 | sequence = kcov->sequence; | |
eec028c9 AK |
789 | area = kcov_remote_area_get(size); |
790 | spin_unlock(&kcov_remote_lock); | |
791 | ||
792 | if (!area) { | |
793 | area = vmalloc(size * sizeof(unsigned long)); | |
794 | if (!area) { | |
795 | t->kcov = NULL; | |
67b3d3cc | 796 | kcov_put(kcov); |
eec028c9 AK |
797 | return; |
798 | } | |
799 | } | |
800 | /* Reset coverage size. */ | |
801 | *(u64 *)area = 0; | |
802 | ||
eec028c9 AK |
803 | kcov_start(t, size, area, mode, sequence); |
804 | ||
805 | } | |
806 | EXPORT_SYMBOL(kcov_remote_start); | |
807 | ||
808 | static void kcov_move_area(enum kcov_mode mode, void *dst_area, | |
809 | unsigned int dst_area_size, void *src_area) | |
810 | { | |
811 | u64 word_size = sizeof(unsigned long); | |
812 | u64 count_size, entry_size_log; | |
813 | u64 dst_len, src_len; | |
814 | void *dst_entries, *src_entries; | |
815 | u64 dst_occupied, dst_free, bytes_to_move, entries_moved; | |
816 | ||
817 | kcov_debug("%px %u <= %px %lu\n", | |
818 | dst_area, dst_area_size, src_area, *(unsigned long *)src_area); | |
819 | ||
820 | switch (mode) { | |
821 | case KCOV_MODE_TRACE_PC: | |
822 | dst_len = READ_ONCE(*(unsigned long *)dst_area); | |
823 | src_len = *(unsigned long *)src_area; | |
824 | count_size = sizeof(unsigned long); | |
825 | entry_size_log = __ilog2_u64(sizeof(unsigned long)); | |
826 | break; | |
827 | case KCOV_MODE_TRACE_CMP: | |
828 | dst_len = READ_ONCE(*(u64 *)dst_area); | |
829 | src_len = *(u64 *)src_area; | |
830 | count_size = sizeof(u64); | |
831 | BUILD_BUG_ON(!is_power_of_2(KCOV_WORDS_PER_CMP)); | |
832 | entry_size_log = __ilog2_u64(sizeof(u64) * KCOV_WORDS_PER_CMP); | |
833 | break; | |
834 | default: | |
835 | WARN_ON(1); | |
836 | return; | |
837 | } | |
838 | ||
839 | /* As arm can't divide u64 integers use log of entry size. */ | |
840 | if (dst_len > ((dst_area_size * word_size - count_size) >> | |
841 | entry_size_log)) | |
842 | return; | |
843 | dst_occupied = count_size + (dst_len << entry_size_log); | |
844 | dst_free = dst_area_size * word_size - dst_occupied; | |
845 | bytes_to_move = min(dst_free, src_len << entry_size_log); | |
846 | dst_entries = dst_area + dst_occupied; | |
847 | src_entries = src_area + count_size; | |
848 | memcpy(dst_entries, src_entries, bytes_to_move); | |
849 | entries_moved = bytes_to_move >> entry_size_log; | |
850 | ||
851 | switch (mode) { | |
852 | case KCOV_MODE_TRACE_PC: | |
853 | WRITE_ONCE(*(unsigned long *)dst_area, dst_len + entries_moved); | |
854 | break; | |
855 | case KCOV_MODE_TRACE_CMP: | |
856 | WRITE_ONCE(*(u64 *)dst_area, dst_len + entries_moved); | |
857 | break; | |
858 | default: | |
859 | break; | |
860 | } | |
861 | } | |
862 | ||
863 | /* See the comment before kcov_remote_start() for usage details. */ | |
864 | void kcov_remote_stop(void) | |
865 | { | |
866 | struct task_struct *t = current; | |
867 | struct kcov *kcov = t->kcov; | |
868 | void *area = t->kcov_area; | |
869 | unsigned int size = t->kcov_size; | |
870 | int sequence = t->kcov_sequence; | |
871 | ||
3c61df38 | 872 | if (!kcov) |
eec028c9 | 873 | return; |
eec028c9 AK |
874 | |
875 | kcov_stop(t); | |
876 | t->kcov = NULL; | |
877 | ||
878 | spin_lock(&kcov->lock); | |
879 | /* | |
880 | * KCOV_DISABLE could have been called between kcov_remote_start() | |
881 | * and kcov_remote_stop(), hence the check. | |
882 | */ | |
eec028c9 AK |
883 | if (sequence == kcov->sequence && kcov->remote) |
884 | kcov_move_area(kcov->mode, kcov->area, kcov->size, area); | |
885 | spin_unlock(&kcov->lock); | |
886 | ||
887 | spin_lock(&kcov_remote_lock); | |
888 | kcov_remote_area_put(area, size); | |
889 | spin_unlock(&kcov_remote_lock); | |
890 | ||
891 | kcov_put(kcov); | |
892 | } | |
893 | EXPORT_SYMBOL(kcov_remote_stop); | |
894 | ||
895 | /* See the comment before kcov_remote_start() for usage details. */ | |
896 | u64 kcov_common_handle(void) | |
897 | { | |
898 | return current->kcov_handle; | |
899 | } | |
900 | EXPORT_SYMBOL(kcov_common_handle); | |
901 | ||
5c9a8750 DV |
902 | static int __init kcov_init(void) |
903 | { | |
df4565f9 NS |
904 | /* |
905 | * The kcov debugfs file won't ever get removed and thus, | |
906 | * there is no need to protect it against removal races. The | |
907 | * use of debugfs_create_file_unsafe() is actually safe here. | |
908 | */ | |
ec9672d5 GKH |
909 | debugfs_create_file_unsafe("kcov", 0600, NULL, NULL, &kcov_fops); |
910 | ||
5c9a8750 DV |
911 | return 0; |
912 | } | |
913 | ||
914 | device_initcall(kcov_init); |