1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * KCSAN test with various race scenarious to test runtime behaviour. Since the
4 * interface with which KCSAN's reports are obtained is via the console, this is
5 * the output we should verify. For each test case checks the presence (or
6 * absence) of generated reports. Relies on 'console' tracepoint to capture
7 * reports as they appear in the kernel log.
8 *
9 * Makes use of KUnit for test organization, and the Torture framework for test
10 * thread control.
11 *
12 * Copyright (C) 2020, Google LLC.
13 * Author: Marco Elver <elver@google.com>
14 */
15
16 #define pr_fmt(fmt) "kcsan_test: " fmt
17
18 #include <kunit/test.h>
19 #include <linux/atomic.h>
20 #include <linux/bitops.h>
21 #include <linux/jiffies.h>
22 #include <linux/kcsan-checks.h>
23 #include <linux/kernel.h>
24 #include <linux/mutex.h>
25 #include <linux/sched.h>
26 #include <linux/seqlock.h>
27 #include <linux/spinlock.h>
28 #include <linux/string.h>
29 #include <linux/timer.h>
30 #include <linux/torture.h>
31 #include <linux/tracepoint.h>
32 #include <linux/types.h>
33 #include <trace/events/printk.h>
34
35 #define KCSAN_TEST_REQUIRES(test, cond) do { \
36 if (!(cond)) \
37 kunit_skip((test), "Test requires: " #cond); \
38 } while (0)
39
40 #ifdef CONFIG_CC_HAS_TSAN_COMPOUND_READ_BEFORE_WRITE
41 #define __KCSAN_ACCESS_RW(alt) (KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE)
42 #else
43 #define __KCSAN_ACCESS_RW(alt) (alt)
44 #endif
45
46 /* Points to current test-case memory access "kernels". */
47 static void (*access_kernels[2])(void);
48
49 static struct task_struct **threads; /* Lists of threads. */
50 static unsigned long end_time; /* End time of test. */
51
52 /* Report as observed from console. */
53 static struct {
54 spinlock_t lock;
55 int nlines;
56 char lines[3][512];
57 } observed = {
58 .lock = __SPIN_LOCK_UNLOCKED(observed.lock),
59 };
60
61 /* Setup test checking loop. */
62 static __no_kcsan inline void
63 begin_test_checks(void (*func1)(void), void (*func2)(void))
64 {
65 kcsan_disable_current();
66
67 /*
68 * Require at least as long as KCSAN_REPORT_ONCE_IN_MS, to ensure at
69 * least one race is reported.
70 */
71 end_time = jiffies + msecs_to_jiffies(CONFIG_KCSAN_REPORT_ONCE_IN_MS + 500);
72
73 /* Signal start; release potential initialization of shared data. */
74 smp_store_release(&access_kernels[0], func1);
75 smp_store_release(&access_kernels[1], func2);
76 }
77
78 /* End test checking loop. */
79 static __no_kcsan inline bool
80 end_test_checks(bool stop)
81 {
82 if (!stop && time_before(jiffies, end_time)) {
83 /* Continue checking */
84 might_sleep();
85 return false;
86 }
87
88 kcsan_enable_current();
89 return true;
90 }
91
92 /*
93 * Probe for console output: checks if a race was reported, and obtains observed
94 * lines of interest.
95 */
96 __no_kcsan
97 static void probe_console(void *ignore, const char *buf, size_t len)
98 {
99 unsigned long flags;
100 int nlines;
101
102 /*
103 * Note that KCSAN reports under a global lock, so we do not risk the
104 * possibility of having multiple reports interleaved. If that were the
105 * case, we'd expect tests to fail.
106 */
107
108 spin_lock_irqsave(&observed.lock, flags);
109 nlines = observed.nlines;
110
111 if (strnstr(buf, "BUG: KCSAN: ", len) && strnstr(buf, "test_", len)) {
112 /*
113 * KCSAN report and related to the test.
114 *
115 * The provided @buf is not NUL-terminated; copy no more than
116 * @len bytes and let strscpy() add the missing NUL-terminator.
117 */
118 strscpy(observed.lines[0], buf, min(len + 1, sizeof(observed.lines[0])));
119 nlines = 1;
120 } else if ((nlines == 1 || nlines == 2) && strnstr(buf, "bytes by", len)) {
121 strscpy(observed.lines[nlines++], buf, min(len + 1, sizeof(observed.lines[0])));
122
123 if (strnstr(buf, "race at unknown origin", len)) {
124 if (WARN_ON(nlines != 2))
125 goto out;
126
127 /* No second line of interest. */
128 strcpy(observed.lines[nlines++], "<none>");
129 }
130 }
131
132 out:
133 WRITE_ONCE(observed.nlines, nlines); /* Publish new nlines. */
134 spin_unlock_irqrestore(&observed.lock, flags);
135 }
136
137 /* Check if a report related to the test exists. */
138 __no_kcsan
139 static bool report_available(void)
140 {
141 return READ_ONCE(observed.nlines) == ARRAY_SIZE(observed.lines);
142 }
143
144 /* Report information we expect in a report. */
145 struct expect_report {
146 /* Access information of both accesses. */
147 struct {
148 void *fn; /* Function pointer to expected function of top frame. */
149 void *addr; /* Address of access; unchecked if NULL. */
150 size_t size; /* Size of access; unchecked if @addr is NULL. */
151 int type; /* Access type, see KCSAN_ACCESS definitions. */
152 } access[2];
153 };
154
155 /* Check observed report matches information in @r. */
156 __no_kcsan
157 static bool __report_matches(const struct expect_report *r)
158 {
159 const bool is_assert = (r->access[0].type | r->access[1].type) & KCSAN_ACCESS_ASSERT;
160 bool ret = false;
161 unsigned long flags;
162 typeof(*observed.lines) *expect;
163 const char *end;
164 char *cur;
165 int i;
166
167 /* Doubled-checked locking. */
168 if (!report_available())
169 return false;
170
171 expect = kmalloc(sizeof(observed.lines), GFP_KERNEL);
172 if (WARN_ON(!expect))
173 return false;
174
175 /* Generate expected report contents. */
176
177 /* Title */
178 cur = expect[0];
179 end = &expect[0][sizeof(expect[0]) - 1];
180 cur += scnprintf(cur, end - cur, "BUG: KCSAN: %s in ",
181 is_assert ? "assert: race" : "data-race");
182 if (r->access[1].fn) {
183 char tmp[2][64];
184 int cmp;
185
186 /* Expect lexographically sorted function names in title. */
187 scnprintf(tmp[0], sizeof(tmp[0]), "%pS", r->access[0].fn);
188 scnprintf(tmp[1], sizeof(tmp[1]), "%pS", r->access[1].fn);
189 cmp = strcmp(tmp[0], tmp[1]);
190 cur += scnprintf(cur, end - cur, "%ps / %ps",
191 cmp < 0 ? r->access[0].fn : r->access[1].fn,
192 cmp < 0 ? r->access[1].fn : r->access[0].fn);
193 } else {
194 scnprintf(cur, end - cur, "%pS", r->access[0].fn);
195 /* The exact offset won't match, remove it. */
196 cur = strchr(expect[0], '+');
197 if (cur)
198 *cur = '\0';
199 }
200
201 /* Access 1 */
202 cur = expect[1];
203 end = &expect[1][sizeof(expect[1]) - 1];
204 if (!r->access[1].fn)
205 cur += scnprintf(cur, end - cur, "race at unknown origin, with ");
206
207 /* Access 1 & 2 */
208 for (i = 0; i < 2; ++i) {
209 const int ty = r->access[i].type;
210 const char *const access_type =
211 (ty & KCSAN_ACCESS_ASSERT) ?
212 ((ty & KCSAN_ACCESS_WRITE) ?
213 "assert no accesses" :
214 "assert no writes") :
215 ((ty & KCSAN_ACCESS_WRITE) ?
216 ((ty & KCSAN_ACCESS_COMPOUND) ?
217 "read-write" :
218 "write") :
219 "read");
220 const bool is_atomic = (ty & KCSAN_ACCESS_ATOMIC);
221 const bool is_scoped = (ty & KCSAN_ACCESS_SCOPED);
222 const char *const access_type_aux =
223 (is_atomic && is_scoped) ? " (marked, reordered)"
224 : (is_atomic ? " (marked)"
225 : (is_scoped ? " (reordered)" : ""));
226
227 if (i == 1) {
228 /* Access 2 */
229 cur = expect[2];
230 end = &expect[2][sizeof(expect[2]) - 1];
231
232 if (!r->access[1].fn) {
233 /* Dummy string if no second access is available. */
234 strcpy(cur, "<none>");
235 break;
236 }
237 }
238
239 cur += scnprintf(cur, end - cur, "%s%s to ", access_type,
240 access_type_aux);
241
242 if (r->access[i].addr) /* Address is optional. */
243 cur += scnprintf(cur, end - cur, "0x%px of %zu bytes",
244 r->access[i].addr, r->access[i].size);
245 }
246
247 spin_lock_irqsave(&observed.lock, flags);
248 if (!report_available())
249 goto out; /* A new report is being captured. */
250
251 /* Finally match expected output to what we actually observed. */
252 ret = strstr(observed.lines[0], expect[0]) &&
253 /* Access info may appear in any order. */
254 ((strstr(observed.lines[1], expect[1]) &&
255 strstr(observed.lines[2], expect[2])) ||
256 (strstr(observed.lines[1], expect[2]) &&
257 strstr(observed.lines[2], expect[1])));
258 out:
259 spin_unlock_irqrestore(&observed.lock, flags);
260 kfree(expect);
261 return ret;
262 }
263
264 static __always_inline const struct expect_report *
265 __report_set_scoped(struct expect_report *r, int accesses)
266 {
267 BUILD_BUG_ON(accesses > 3);
268
269 if (accesses & 1)
270 r->access[0].type |= KCSAN_ACCESS_SCOPED;
271 else
272 r->access[0].type &= ~KCSAN_ACCESS_SCOPED;
273
274 if (accesses & 2)
275 r->access[1].type |= KCSAN_ACCESS_SCOPED;
276 else
277 r->access[1].type &= ~KCSAN_ACCESS_SCOPED;
278
279 return r;
280 }
281
282 __no_kcsan
283 static bool report_matches_any_reordered(struct expect_report *r)
284 {
285 return __report_matches(__report_set_scoped(r, 0)) ||
286 __report_matches(__report_set_scoped(r, 1)) ||
287 __report_matches(__report_set_scoped(r, 2)) ||
288 __report_matches(__report_set_scoped(r, 3));
289 }
290
291 #ifdef CONFIG_KCSAN_WEAK_MEMORY
292 /* Due to reordering accesses, any access may appear as "(reordered)". */
293 #define report_matches report_matches_any_reordered
294 #else
295 #define report_matches __report_matches
296 #endif
297
298 /* ===== Test kernels ===== */
299
300 static long test_sink;
301 static long test_var;
302 /* @test_array should be large enough to fall into multiple watchpoint slots. */
303 static long test_array[3 * PAGE_SIZE / sizeof(long)];
304 static struct {
305 long val[8];
306 } test_struct;
307 static long __data_racy test_data_racy;
308 static DEFINE_SEQLOCK(test_seqlock);
309 static DEFINE_SPINLOCK(test_spinlock);
310 static DEFINE_MUTEX(test_mutex);
311
312 /*
313 * Helper to avoid compiler optimizing out reads, and to generate source values
314 * for writes.
315 */
316 __no_kcsan
317 static noinline void sink_value(long v) { WRITE_ONCE(test_sink, v); }
318
319 /*
320 * Generates a delay and some accesses that enter the runtime but do not produce
321 * data races.
322 */
323 static noinline void test_delay(int iter)
324 {
325 while (iter--)
326 sink_value(READ_ONCE(test_sink));
327 }
328
329 static noinline void test_kernel_read(void) { sink_value(test_var); }
330
331 static noinline void test_kernel_write(void)
332 {
333 test_var = READ_ONCE_NOCHECK(test_sink) + 1;
334 }
335
336 static noinline void test_kernel_write_nochange(void) { test_var = 42; }
337
338 /* Suffixed by value-change exception filter. */
339 static noinline void test_kernel_write_nochange_rcu(void) { test_var = 42; }
340
341 static noinline void test_kernel_read_atomic(void)
342 {
343 sink_value(READ_ONCE(test_var));
344 }
345
346 static noinline void test_kernel_write_atomic(void)
347 {
348 WRITE_ONCE(test_var, READ_ONCE_NOCHECK(test_sink) + 1);
349 }
350
351 static noinline void test_kernel_atomic_rmw(void)
352 {
353 /* Use builtin, so we can set up the "bad" atomic/non-atomic scenario. */
354 __atomic_fetch_add(&test_var, 1, __ATOMIC_RELAXED);
355 }
356
357 __no_kcsan
358 static noinline void test_kernel_write_uninstrumented(void) { test_var++; }
359
360 static noinline void test_kernel_data_race(void) { data_race(test_var++); }
361
362 static noinline void test_kernel_data_racy_qualifier(void) { test_data_racy++; }
363
364 static noinline void test_kernel_assert_writer(void)
365 {
366 ASSERT_EXCLUSIVE_WRITER(test_var);
367 }
368
369 static noinline void test_kernel_assert_access(void)
370 {
371 ASSERT_EXCLUSIVE_ACCESS(test_var);
372 }
373
374 #define TEST_CHANGE_BITS 0xff00ff00
375
376 static noinline void test_kernel_change_bits(void)
377 {
378 if (IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) {
379 /*
380 * Avoid race of unknown origin for this test, just pretend they
381 * are atomic.
382 */
383 kcsan_nestable_atomic_begin();
384 test_var ^= TEST_CHANGE_BITS;
385 kcsan_nestable_atomic_end();
386 } else
387 WRITE_ONCE(test_var, READ_ONCE(test_var) ^ TEST_CHANGE_BITS);
388 }
389
390 static noinline void test_kernel_assert_bits_change(void)
391 {
392 ASSERT_EXCLUSIVE_BITS(test_var, TEST_CHANGE_BITS);
393 }
394
395 static noinline void test_kernel_assert_bits_nochange(void)
396 {
397 ASSERT_EXCLUSIVE_BITS(test_var, ~TEST_CHANGE_BITS);
398 }
399
400 /*
401 * Scoped assertions do trigger anywhere in scope. However, the report should
402 * still only point at the start of the scope.
403 */
404 static noinline void test_enter_scope(void)
405 {
406 int x = 0;
407
408 /* Unrelated accesses to scoped assert. */
409 READ_ONCE(test_sink);
410 kcsan_check_read(&x, sizeof(x));
411 }
412
413 static noinline void test_kernel_assert_writer_scoped(void)
414 {
415 ASSERT_EXCLUSIVE_WRITER_SCOPED(test_var);
416 test_enter_scope();
417 }
418
419 static noinline void test_kernel_assert_access_scoped(void)
420 {
421 ASSERT_EXCLUSIVE_ACCESS_SCOPED(test_var);
422 test_enter_scope();
423 }
424
425 static noinline void test_kernel_rmw_array(void)
426 {
427 int i;
428
429 for (i = 0; i < ARRAY_SIZE(test_array); ++i)
430 test_array[i]++;
431 }
432
433 static noinline void test_kernel_write_struct(void)
434 {
435 kcsan_check_write(&test_struct, sizeof(test_struct));
436 kcsan_disable_current();
437 test_struct.val[3]++; /* induce value change */
438 kcsan_enable_current();
439 }
440
441 static noinline void test_kernel_write_struct_part(void)
442 {
443 test_struct.val[3] = 42;
444 }
445
446 static noinline void test_kernel_read_struct_zero_size(void)
447 {
448 kcsan_check_read(&test_struct.val[3], 0);
449 }
450
451 static noinline void test_kernel_jiffies_reader(void)
452 {
453 sink_value((long)jiffies);
454 }
455
456 static noinline void test_kernel_seqlock_reader(void)
457 {
458 unsigned int seq;
459
460 do {
461 seq = read_seqbegin(&test_seqlock);
462 sink_value(test_var);
463 } while (read_seqretry(&test_seqlock, seq));
464 }
465
466 static noinline void test_kernel_seqlock_writer(void)
467 {
468 unsigned long flags;
469
470 write_seqlock_irqsave(&test_seqlock, flags);
471 test_var++;
472 write_sequnlock_irqrestore(&test_seqlock, flags);
473 }
474
475 static noinline void test_kernel_atomic_builtins(void)
476 {
477 /*
478 * Generate concurrent accesses, expecting no reports, ensuring KCSAN
479 * treats builtin atomics as actually atomic.
480 */
481 __atomic_load_n(&test_var, __ATOMIC_RELAXED);
482 }
483
484 static noinline void test_kernel_xor_1bit(void)
485 {
486 /* Do not report data races between the read-writes. */
487 kcsan_nestable_atomic_begin();
488 test_var ^= 0x10000;
489 kcsan_nestable_atomic_end();
490 }
491
492 #define TEST_KERNEL_LOCKED(name, acquire, release) \
493 static noinline void test_kernel_##name(void) \
494 { \
495 long *flag = &test_struct.val[0]; \
496 long v = 0; \
497 if (!(acquire)) \
498 return; \
499 while (v++ < 100) { \
500 test_var++; \
501 barrier(); \
502 } \
503 release; \
504 test_delay(10); \
505 }
506
507 TEST_KERNEL_LOCKED(with_memorder,
508 cmpxchg_acquire(flag, 0, 1) == 0,
509 smp_store_release(flag, 0));
510 TEST_KERNEL_LOCKED(wrong_memorder,
511 cmpxchg_relaxed(flag, 0, 1) == 0,
512 WRITE_ONCE(*flag, 0));
513 TEST_KERNEL_LOCKED(atomic_builtin_with_memorder,
514 __atomic_compare_exchange_n(flag, &v, 1, 0, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED),
515 __atomic_store_n(flag, 0, __ATOMIC_RELEASE));
516 TEST_KERNEL_LOCKED(atomic_builtin_wrong_memorder,
517 __atomic_compare_exchange_n(flag, &v, 1, 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED),
518 __atomic_store_n(flag, 0, __ATOMIC_RELAXED));
519
520 /* ===== Test cases ===== */
521
522 /*
523 * Tests that various barriers have the expected effect on internal state. Not
524 * exhaustive on atomic_t operations. Unlike the selftest, also checks for
525 * too-strict barrier instrumentation; these can be tolerated, because it does
526 * not cause false positives, but at least we should be aware of such cases.
527 */
528 static void test_barrier_nothreads(struct kunit *test)
529 {
530 #ifdef CONFIG_KCSAN_WEAK_MEMORY
531 struct kcsan_scoped_access *reorder_access = ¤t->kcsan_ctx.reorder_access;
532 #else
533 struct kcsan_scoped_access *reorder_access = NULL;
534 #endif
535 arch_spinlock_t arch_spinlock = __ARCH_SPIN_LOCK_UNLOCKED;
536 atomic_t dummy;
537
538 KCSAN_TEST_REQUIRES(test, reorder_access != NULL);
539 KCSAN_TEST_REQUIRES(test, IS_ENABLED(CONFIG_SMP));
540
541 #define __KCSAN_EXPECT_BARRIER(access_type, barrier, order_before, name) \
542 do { \
543 reorder_access->type = (access_type) | KCSAN_ACCESS_SCOPED; \
544 reorder_access->size = sizeof(test_var); \
545 barrier; \
546 KUNIT_EXPECT_EQ_MSG(test, reorder_access->size, \
547 order_before ? 0 : sizeof(test_var), \
548 "improperly instrumented type=(" #access_type "): " name); \
549 } while (0)
550 #define KCSAN_EXPECT_READ_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(0, b, o, #b)
551 #define KCSAN_EXPECT_WRITE_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(KCSAN_ACCESS_WRITE, b, o, #b)
552 #define KCSAN_EXPECT_RW_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE, b, o, #b)
553
554 /*
555 * Lockdep initialization can strengthen certain locking operations due
556 * to calling into instrumented files; "warm up" our locks.
557 */
558 spin_lock(&test_spinlock);
559 spin_unlock(&test_spinlock);
560 mutex_lock(&test_mutex);
561 mutex_unlock(&test_mutex);
562
563 /* Force creating a valid entry in reorder_access first. */
564 test_var = 0;
565 while (test_var++ < 1000000 && reorder_access->size != sizeof(test_var))
566 __kcsan_check_read(&test_var, sizeof(test_var));
567 KUNIT_ASSERT_EQ(test, reorder_access->size, sizeof(test_var));
568
569 kcsan_nestable_atomic_begin(); /* No watchpoints in called functions. */
570
571 KCSAN_EXPECT_READ_BARRIER(mb(), true);
572 KCSAN_EXPECT_READ_BARRIER(wmb(), false);
573 KCSAN_EXPECT_READ_BARRIER(rmb(), true);
574 KCSAN_EXPECT_READ_BARRIER(smp_mb(), true);
575 KCSAN_EXPECT_READ_BARRIER(smp_wmb(), false);
576 KCSAN_EXPECT_READ_BARRIER(smp_rmb(), true);
577 KCSAN_EXPECT_READ_BARRIER(dma_wmb(), false);
578 KCSAN_EXPECT_READ_BARRIER(dma_rmb(), true);
579 KCSAN_EXPECT_READ_BARRIER(smp_mb__before_atomic(), true);
580 KCSAN_EXPECT_READ_BARRIER(smp_mb__after_atomic(), true);
581 KCSAN_EXPECT_READ_BARRIER(smp_mb__after_spinlock(), true);
582 KCSAN_EXPECT_READ_BARRIER(smp_store_mb(test_var, 0), true);
583 KCSAN_EXPECT_READ_BARRIER(smp_load_acquire(&test_var), false);
584 KCSAN_EXPECT_READ_BARRIER(smp_store_release(&test_var, 0), true);
585 KCSAN_EXPECT_READ_BARRIER(xchg(&test_var, 0), true);
586 KCSAN_EXPECT_READ_BARRIER(xchg_release(&test_var, 0), true);
587 KCSAN_EXPECT_READ_BARRIER(xchg_relaxed(&test_var, 0), false);
588 KCSAN_EXPECT_READ_BARRIER(cmpxchg(&test_var, 0, 0), true);
589 KCSAN_EXPECT_READ_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
590 KCSAN_EXPECT_READ_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
591 KCSAN_EXPECT_READ_BARRIER(atomic_read(&dummy), false);
592 KCSAN_EXPECT_READ_BARRIER(atomic_read_acquire(&dummy), false);
593 KCSAN_EXPECT_READ_BARRIER(atomic_set(&dummy, 0), false);
594 KCSAN_EXPECT_READ_BARRIER(atomic_set_release(&dummy, 0), true);
595 KCSAN_EXPECT_READ_BARRIER(atomic_add(1, &dummy), false);
596 KCSAN_EXPECT_READ_BARRIER(atomic_add_return(1, &dummy), true);
597 KCSAN_EXPECT_READ_BARRIER(atomic_add_return_acquire(1, &dummy), false);
598 KCSAN_EXPECT_READ_BARRIER(atomic_add_return_release(1, &dummy), true);
599 KCSAN_EXPECT_READ_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
600 KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add(1, &dummy), true);
601 KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
602 KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_release(1, &dummy), true);
603 KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
604 KCSAN_EXPECT_READ_BARRIER(test_and_set_bit(0, &test_var), true);
605 KCSAN_EXPECT_READ_BARRIER(test_and_clear_bit(0, &test_var), true);
606 KCSAN_EXPECT_READ_BARRIER(test_and_change_bit(0, &test_var), true);
607 KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock(0, &test_var), true);
608 KCSAN_EXPECT_READ_BARRIER(__clear_bit_unlock(0, &test_var), true);
609 KCSAN_EXPECT_READ_BARRIER(arch_spin_lock(&arch_spinlock), false);
610 KCSAN_EXPECT_READ_BARRIER(arch_spin_unlock(&arch_spinlock), true);
611 KCSAN_EXPECT_READ_BARRIER(spin_lock(&test_spinlock), false);
612 KCSAN_EXPECT_READ_BARRIER(spin_unlock(&test_spinlock), true);
613 KCSAN_EXPECT_READ_BARRIER(mutex_lock(&test_mutex), false);
614 KCSAN_EXPECT_READ_BARRIER(mutex_unlock(&test_mutex), true);
615
616 KCSAN_EXPECT_WRITE_BARRIER(mb(), true);
617 KCSAN_EXPECT_WRITE_BARRIER(wmb(), true);
618 KCSAN_EXPECT_WRITE_BARRIER(rmb(), false);
619 KCSAN_EXPECT_WRITE_BARRIER(smp_mb(), true);
620 KCSAN_EXPECT_WRITE_BARRIER(smp_wmb(), true);
621 KCSAN_EXPECT_WRITE_BARRIER(smp_rmb(), false);
622 KCSAN_EXPECT_WRITE_BARRIER(dma_wmb(), true);
623 KCSAN_EXPECT_WRITE_BARRIER(dma_rmb(), false);
624 KCSAN_EXPECT_WRITE_BARRIER(smp_mb__before_atomic(), true);
625 KCSAN_EXPECT_WRITE_BARRIER(smp_mb__after_atomic(), true);
626 KCSAN_EXPECT_WRITE_BARRIER(smp_mb__after_spinlock(), true);
627 KCSAN_EXPECT_WRITE_BARRIER(smp_store_mb(test_var, 0), true);
628 KCSAN_EXPECT_WRITE_BARRIER(smp_load_acquire(&test_var), false);
629 KCSAN_EXPECT_WRITE_BARRIER(smp_store_release(&test_var, 0), true);
630 KCSAN_EXPECT_WRITE_BARRIER(xchg(&test_var, 0), true);
631 KCSAN_EXPECT_WRITE_BARRIER(xchg_release(&test_var, 0), true);
632 KCSAN_EXPECT_WRITE_BARRIER(xchg_relaxed(&test_var, 0), false);
633 KCSAN_EXPECT_WRITE_BARRIER(cmpxchg(&test_var, 0, 0), true);
634 KCSAN_EXPECT_WRITE_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
635 KCSAN_EXPECT_WRITE_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
636 KCSAN_EXPECT_WRITE_BARRIER(atomic_read(&dummy), false);
637 KCSAN_EXPECT_WRITE_BARRIER(atomic_read_acquire(&dummy), false);
638 KCSAN_EXPECT_WRITE_BARRIER(atomic_set(&dummy, 0), false);
639 KCSAN_EXPECT_WRITE_BARRIER(atomic_set_release(&dummy, 0), true);
640 KCSAN_EXPECT_WRITE_BARRIER(atomic_add(1, &dummy), false);
641 KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return(1, &dummy), true);
642 KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_acquire(1, &dummy), false);
643 KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_release(1, &dummy), true);
644 KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
645 KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add(1, &dummy), true);
646 KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
647 KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_release(1, &dummy), true);
648 KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
649 KCSAN_EXPECT_WRITE_BARRIER(test_and_set_bit(0, &test_var), true);
650 KCSAN_EXPECT_WRITE_BARRIER(test_and_clear_bit(0, &test_var), true);
651 KCSAN_EXPECT_WRITE_BARRIER(test_and_change_bit(0, &test_var), true);
652 KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock(0, &test_var), true);
653 KCSAN_EXPECT_WRITE_BARRIER(__clear_bit_unlock(0, &test_var), true);
654 KCSAN_EXPECT_WRITE_BARRIER(arch_spin_lock(&arch_spinlock), false);
655 KCSAN_EXPECT_WRITE_BARRIER(arch_spin_unlock(&arch_spinlock), true);
656 KCSAN_EXPECT_WRITE_BARRIER(spin_lock(&test_spinlock), false);
657 KCSAN_EXPECT_WRITE_BARRIER(spin_unlock(&test_spinlock), true);
658 KCSAN_EXPECT_WRITE_BARRIER(mutex_lock(&test_mutex), false);
659 KCSAN_EXPECT_WRITE_BARRIER(mutex_unlock(&test_mutex), true);
660
661 KCSAN_EXPECT_RW_BARRIER(mb(), true);
662 KCSAN_EXPECT_RW_BARRIER(wmb(), true);
663 KCSAN_EXPECT_RW_BARRIER(rmb(), true);
664 KCSAN_EXPECT_RW_BARRIER(smp_mb(), true);
665 KCSAN_EXPECT_RW_BARRIER(smp_wmb(), true);
666 KCSAN_EXPECT_RW_BARRIER(smp_rmb(), true);
667 KCSAN_EXPECT_RW_BARRIER(dma_wmb(), true);
668 KCSAN_EXPECT_RW_BARRIER(dma_rmb(), true);
669 KCSAN_EXPECT_RW_BARRIER(smp_mb__before_atomic(), true);
670 KCSAN_EXPECT_RW_BARRIER(smp_mb__after_atomic(), true);
671 KCSAN_EXPECT_RW_BARRIER(smp_mb__after_spinlock(), true);
672 KCSAN_EXPECT_RW_BARRIER(smp_store_mb(test_var, 0), true);
673 KCSAN_EXPECT_RW_BARRIER(smp_load_acquire(&test_var), false);
674 KCSAN_EXPECT_RW_BARRIER(smp_store_release(&test_var, 0), true);
675 KCSAN_EXPECT_RW_BARRIER(xchg(&test_var, 0), true);
676 KCSAN_EXPECT_RW_BARRIER(xchg_release(&test_var, 0), true);
677 KCSAN_EXPECT_RW_BARRIER(xchg_relaxed(&test_var, 0), false);
678 KCSAN_EXPECT_RW_BARRIER(cmpxchg(&test_var, 0, 0), true);
679 KCSAN_EXPECT_RW_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
680 KCSAN_EXPECT_RW_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
681 KCSAN_EXPECT_RW_BARRIER(atomic_read(&dummy), false);
682 KCSAN_EXPECT_RW_BARRIER(atomic_read_acquire(&dummy), false);
683 KCSAN_EXPECT_RW_BARRIER(atomic_set(&dummy, 0), false);
684 KCSAN_EXPECT_RW_BARRIER(atomic_set_release(&dummy, 0), true);
685 KCSAN_EXPECT_RW_BARRIER(atomic_add(1, &dummy), false);
686 KCSAN_EXPECT_RW_BARRIER(atomic_add_return(1, &dummy), true);
687 KCSAN_EXPECT_RW_BARRIER(atomic_add_return_acquire(1, &dummy), false);
688 KCSAN_EXPECT_RW_BARRIER(atomic_add_return_release(1, &dummy), true);
689 KCSAN_EXPECT_RW_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
690 KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add(1, &dummy), true);
691 KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
692 KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_release(1, &dummy), true);
693 KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
694 KCSAN_EXPECT_RW_BARRIER(test_and_set_bit(0, &test_var), true);
695 KCSAN_EXPECT_RW_BARRIER(test_and_clear_bit(0, &test_var), true);
696 KCSAN_EXPECT_RW_BARRIER(test_and_change_bit(0, &test_var), true);
697 KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock(0, &test_var), true);
698 KCSAN_EXPECT_RW_BARRIER(__clear_bit_unlock(0, &test_var), true);
699 KCSAN_EXPECT_RW_BARRIER(arch_spin_lock(&arch_spinlock), false);
700 KCSAN_EXPECT_RW_BARRIER(arch_spin_unlock(&arch_spinlock), true);
701 KCSAN_EXPECT_RW_BARRIER(spin_lock(&test_spinlock), false);
702 KCSAN_EXPECT_RW_BARRIER(spin_unlock(&test_spinlock), true);
703 KCSAN_EXPECT_RW_BARRIER(mutex_lock(&test_mutex), false);
704 KCSAN_EXPECT_RW_BARRIER(mutex_unlock(&test_mutex), true);
705 KCSAN_EXPECT_READ_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true);
706 KCSAN_EXPECT_WRITE_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true);
707 KCSAN_EXPECT_RW_BARRIER(xor_unlock_is_negative_byte(1, &test_var), true);
708 kcsan_nestable_atomic_end();
709 }
710
711 /* Simple test with normal data race. */
712 __no_kcsan
713 static void test_basic(struct kunit *test)
714 {
715 struct expect_report expect = {
716 .access = {
717 { test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
718 { test_kernel_read, &test_var, sizeof(test_var), 0 },
719 },
720 };
721 struct expect_report never = {
722 .access = {
723 { test_kernel_read, &test_var, sizeof(test_var), 0 },
724 { test_kernel_read, &test_var, sizeof(test_var), 0 },
725 },
726 };
727 bool match_expect = false;
728 bool match_never = false;
729
730 begin_test_checks(test_kernel_write, test_kernel_read);
731 do {
732 match_expect |= report_matches(&expect);
733 match_never = report_matches(&never);
734 } while (!end_test_checks(match_never));
735 KUNIT_EXPECT_TRUE(test, match_expect);
736 KUNIT_EXPECT_FALSE(test, match_never);
737 }
738
739 /*
740 * Stress KCSAN with lots of concurrent races on different addresses until
741 * timeout.
742 */
743 __no_kcsan
744 static void test_concurrent_races(struct kunit *test)
745 {
746 struct expect_report expect = {
747 .access = {
748 /* NULL will match any address. */
749 { test_kernel_rmw_array, NULL, 0, __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
750 { test_kernel_rmw_array, NULL, 0, __KCSAN_ACCESS_RW(0) },
751 },
752 };
753 struct expect_report never = {
754 .access = {
755 { test_kernel_rmw_array, NULL, 0, 0 },
756 { test_kernel_rmw_array, NULL, 0, 0 },
757 },
758 };
759 bool match_expect = false;
760 bool match_never = false;
761
762 begin_test_checks(test_kernel_rmw_array, test_kernel_rmw_array);
763 do {
764 match_expect |= report_matches(&expect);
765 match_never |= report_matches(&never);
766 } while (!end_test_checks(false));
767 KUNIT_EXPECT_TRUE(test, match_expect); /* Sanity check matches exist. */
768 KUNIT_EXPECT_FALSE(test, match_never);
769 }
770
771 /* Test the KCSAN_REPORT_VALUE_CHANGE_ONLY option. */
772 __no_kcsan
773 static void test_novalue_change(struct kunit *test)
774 {
775 struct expect_report expect_rw = {
776 .access = {
777 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
778 { test_kernel_read, &test_var, sizeof(test_var), 0 },
779 },
780 };
781 struct expect_report expect_ww = {
782 .access = {
783 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
784 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
785 },
786 };
787 bool match_expect = false;
788
789 test_kernel_write_nochange(); /* Reset value. */
790 begin_test_checks(test_kernel_write_nochange, test_kernel_read);
791 do {
792 match_expect = report_matches(&expect_rw) || report_matches(&expect_ww);
793 } while (!end_test_checks(match_expect));
794 if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY))
795 KUNIT_EXPECT_FALSE(test, match_expect);
796 else
797 KUNIT_EXPECT_TRUE(test, match_expect);
798 }
799
800 /*
801 * Test that the rules where the KCSAN_REPORT_VALUE_CHANGE_ONLY option should
802 * never apply work.
803 */
804 __no_kcsan
805 static void test_novalue_change_exception(struct kunit *test)
806 {
807 struct expect_report expect_rw = {
808 .access = {
809 { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
810 { test_kernel_read, &test_var, sizeof(test_var), 0 },
811 },
812 };
813 struct expect_report expect_ww = {
814 .access = {
815 { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
816 { test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
817 },
818 };
819 bool match_expect = false;
820
821 test_kernel_write_nochange_rcu(); /* Reset value. */
822 begin_test_checks(test_kernel_write_nochange_rcu, test_kernel_read);
823 do {
824 match_expect = report_matches(&expect_rw) || report_matches(&expect_ww);
825 } while (!end_test_checks(match_expect));
826 KUNIT_EXPECT_TRUE(test, match_expect);
827 }
828
829 /* Test that data races of unknown origin are reported. */
830 __no_kcsan
831 static void test_unknown_origin(struct kunit *test)
832 {
833 struct expect_report expect = {
834 .access = {
835 { test_kernel_read, &test_var, sizeof(test_var), 0 },
836 { NULL },
837 },
838 };
839 bool match_expect = false;
840
841 begin_test_checks(test_kernel_write_uninstrumented, test_kernel_read);
842 do {
843 match_expect = report_matches(&expect);
844 } while (!end_test_checks(match_expect));
845 if (IS_ENABLED(CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN))
846 KUNIT_EXPECT_TRUE(test, match_expect);
847 else
848 KUNIT_EXPECT_FALSE(test, match_expect);
849 }
850
851 /* Test KCSAN_ASSUME_PLAIN_WRITES_ATOMIC if it is selected. */
852 __no_kcsan
853 static void test_write_write_assume_atomic(struct kunit *test)
854 {
855 struct expect_report expect = {
856 .access = {
857 { test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
858 { test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
859 },
860 };
861 bool match_expect = false;
862
863 begin_test_checks(test_kernel_write, test_kernel_write);
864 do {
865 sink_value(READ_ONCE(test_var)); /* induce value-change */
866 match_expect = report_matches(&expect);
867 } while (!end_test_checks(match_expect));
868 if (IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC))
869 KUNIT_EXPECT_FALSE(test, match_expect);
870 else
871 KUNIT_EXPECT_TRUE(test, match_expect);
872 }
873
874 /*
875 * Test that data races with writes larger than word-size are always reported,
876 * even if KCSAN_ASSUME_PLAIN_WRITES_ATOMIC is selected.
877 */
878 __no_kcsan
879 static void test_write_write_struct(struct kunit *test)
880 {
881 struct expect_report expect = {
882 .access = {
883 { test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
884 { test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
885 },
886 };
887 bool match_expect = false;
888
889 begin_test_checks(test_kernel_write_struct, test_kernel_write_struct);
890 do {
891 match_expect = report_matches(&expect);
892 } while (!end_test_checks(match_expect));
893 KUNIT_EXPECT_TRUE(test, match_expect);
894 }
895
896 /*
897 * Test that data races where only one write is larger than word-size are always
898 * reported, even if KCSAN_ASSUME_PLAIN_WRITES_ATOMIC is selected.
899 */
900 __no_kcsan
901 static void test_write_write_struct_part(struct kunit *test)
902 {
903 struct expect_report expect = {
904 .access = {
905 { test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
906 { test_kernel_write_struct_part, &test_struct.val[3], sizeof(test_struct.val[3]), KCSAN_ACCESS_WRITE },
907 },
908 };
909 bool match_expect = false;
910
911 begin_test_checks(test_kernel_write_struct, test_kernel_write_struct_part);
912 do {
913 match_expect = report_matches(&expect);
914 } while (!end_test_checks(match_expect));
915 KUNIT_EXPECT_TRUE(test, match_expect);
916 }
917
918 /* Test that races with atomic accesses never result in reports. */
919 __no_kcsan
920 static void test_read_atomic_write_atomic(struct kunit *test)
921 {
922 bool match_never = false;
923
924 begin_test_checks(test_kernel_read_atomic, test_kernel_write_atomic);
925 do {
926 match_never = report_available();
927 } while (!end_test_checks(match_never));
928 KUNIT_EXPECT_FALSE(test, match_never);
929 }
930
931 /* Test that a race with an atomic and plain access result in reports. */
932 __no_kcsan
933 static void test_read_plain_atomic_write(struct kunit *test)
934 {
935 struct expect_report expect = {
936 .access = {
937 { test_kernel_read, &test_var, sizeof(test_var), 0 },
938 { test_kernel_write_atomic, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC },
939 },
940 };
941 bool match_expect = false;
942
943 KCSAN_TEST_REQUIRES(test, !IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS));
944
945 begin_test_checks(test_kernel_read, test_kernel_write_atomic);
946 do {
947 match_expect = report_matches(&expect);
948 } while (!end_test_checks(match_expect));
949 KUNIT_EXPECT_TRUE(test, match_expect);
950 }
951
952 /* Test that atomic RMWs generate correct report. */
953 __no_kcsan
954 static void test_read_plain_atomic_rmw(struct kunit *test)
955 {
956 struct expect_report expect = {
957 .access = {
958 { test_kernel_read, &test_var, sizeof(test_var), 0 },
959 { test_kernel_atomic_rmw, &test_var, sizeof(test_var),
960 KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC },
961 },
962 };
963 bool match_expect = false;
964
965 KCSAN_TEST_REQUIRES(test, !IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS));
966
967 begin_test_checks(test_kernel_read, test_kernel_atomic_rmw);
968 do {
969 match_expect = report_matches(&expect);
970 } while (!end_test_checks(match_expect));
971 KUNIT_EXPECT_TRUE(test, match_expect);
972 }
973
974 /* Zero-sized accesses should never cause data race reports. */
975 __no_kcsan
976 static void test_zero_size_access(struct kunit *test)
977 {
978 struct expect_report expect = {
979 .access = {
980 { test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
981 { test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
982 },
983 };
984 struct expect_report never = {
985 .access = {
986 { test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
987 { test_kernel_read_struct_zero_size, &test_struct.val[3], 0, 0 },
988 },
989 };
990 bool match_expect = false;
991 bool match_never = false;
992
993 begin_test_checks(test_kernel_write_struct, test_kernel_read_struct_zero_size);
994 do {
995 match_expect |= report_matches(&expect);
996 match_never = report_matches(&never);
997 } while (!end_test_checks(match_never));
998 KUNIT_EXPECT_TRUE(test, match_expect); /* Sanity check. */
999 KUNIT_EXPECT_FALSE(test, match_never);
1000 }
1001
1002 /* Test the data_race() macro. */
1003 __no_kcsan
1004 static void test_data_race(struct kunit *test)
1005 {
1006 bool match_never = false;
1007
1008 begin_test_checks(test_kernel_data_race, test_kernel_data_race);
1009 do {
1010 match_never = report_available();
1011 } while (!end_test_checks(match_never));
1012 KUNIT_EXPECT_FALSE(test, match_never);
1013 }
1014
1015 /* Test the __data_racy type qualifier. */
1016 __no_kcsan
1017 static void test_data_racy_qualifier(struct kunit *test)
1018 {
1019 bool match_never = false;
1020
1021 begin_test_checks(test_kernel_data_racy_qualifier, test_kernel_data_racy_qualifier);
1022 do {
1023 match_never = report_available();
1024 } while (!end_test_checks(match_never));
1025 KUNIT_EXPECT_FALSE(test, match_never);
1026 }
1027
1028 __no_kcsan
1029 static void test_assert_exclusive_writer(struct kunit *test)
1030 {
1031 struct expect_report expect = {
1032 .access = {
1033 { test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1034 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
1035 },
1036 };
1037 bool match_expect = false;
1038
1039 begin_test_checks(test_kernel_assert_writer, test_kernel_write_nochange);
1040 do {
1041 match_expect = report_matches(&expect);
1042 } while (!end_test_checks(match_expect));
1043 KUNIT_EXPECT_TRUE(test, match_expect);
1044 }
1045
1046 __no_kcsan
1047 static void test_assert_exclusive_access(struct kunit *test)
1048 {
1049 struct expect_report expect = {
1050 .access = {
1051 { test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
1052 { test_kernel_read, &test_var, sizeof(test_var), 0 },
1053 },
1054 };
1055 bool match_expect = false;
1056
1057 begin_test_checks(test_kernel_assert_access, test_kernel_read);
1058 do {
1059 match_expect = report_matches(&expect);
1060 } while (!end_test_checks(match_expect));
1061 KUNIT_EXPECT_TRUE(test, match_expect);
1062 }
1063
1064 __no_kcsan
1065 static void test_assert_exclusive_access_writer(struct kunit *test)
1066 {
1067 struct expect_report expect_access_writer = {
1068 .access = {
1069 { test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
1070 { test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1071 },
1072 };
1073 struct expect_report expect_access_access = {
1074 .access = {
1075 { test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
1076 { test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
1077 },
1078 };
1079 struct expect_report never = {
1080 .access = {
1081 { test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1082 { test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1083 },
1084 };
1085 bool match_expect_access_writer = false;
1086 bool match_expect_access_access = false;
1087 bool match_never = false;
1088
1089 begin_test_checks(test_kernel_assert_access, test_kernel_assert_writer);
1090 do {
1091 match_expect_access_writer |= report_matches(&expect_access_writer);
1092 match_expect_access_access |= report_matches(&expect_access_access);
1093 match_never |= report_matches(&never);
1094 } while (!end_test_checks(match_never));
1095 KUNIT_EXPECT_TRUE(test, match_expect_access_writer);
1096 KUNIT_EXPECT_TRUE(test, match_expect_access_access);
1097 KUNIT_EXPECT_FALSE(test, match_never);
1098 }
1099
1100 __no_kcsan
1101 static void test_assert_exclusive_bits_change(struct kunit *test)
1102 {
1103 struct expect_report expect = {
1104 .access = {
1105 { test_kernel_assert_bits_change, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1106 { test_kernel_change_bits, &test_var, sizeof(test_var),
1107 KCSAN_ACCESS_WRITE | (IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS) ? 0 : KCSAN_ACCESS_ATOMIC) },
1108 },
1109 };
1110 bool match_expect = false;
1111
1112 begin_test_checks(test_kernel_assert_bits_change, test_kernel_change_bits);
1113 do {
1114 match_expect = report_matches(&expect);
1115 } while (!end_test_checks(match_expect));
1116 KUNIT_EXPECT_TRUE(test, match_expect);
1117 }
1118
1119 __no_kcsan
1120 static void test_assert_exclusive_bits_nochange(struct kunit *test)
1121 {
1122 bool match_never = false;
1123
1124 begin_test_checks(test_kernel_assert_bits_nochange, test_kernel_change_bits);
1125 do {
1126 match_never = report_available();
1127 } while (!end_test_checks(match_never));
1128 KUNIT_EXPECT_FALSE(test, match_never);
1129 }
1130
1131 __no_kcsan
1132 static void test_assert_exclusive_writer_scoped(struct kunit *test)
1133 {
1134 struct expect_report expect_start = {
1135 .access = {
1136 { test_kernel_assert_writer_scoped, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_SCOPED },
1137 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
1138 },
1139 };
1140 struct expect_report expect_inscope = {
1141 .access = {
1142 { test_enter_scope, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_SCOPED },
1143 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
1144 },
1145 };
1146 bool match_expect_start = false;
1147 bool match_expect_inscope = false;
1148
1149 begin_test_checks(test_kernel_assert_writer_scoped, test_kernel_write_nochange);
1150 do {
1151 match_expect_start |= report_matches(&expect_start);
1152 match_expect_inscope |= report_matches(&expect_inscope);
1153 } while (!end_test_checks(match_expect_inscope));
1154 KUNIT_EXPECT_TRUE(test, match_expect_start);
1155 KUNIT_EXPECT_FALSE(test, match_expect_inscope);
1156 }
1157
1158 __no_kcsan
1159 static void test_assert_exclusive_access_scoped(struct kunit *test)
1160 {
1161 struct expect_report expect_start1 = {
1162 .access = {
1163 { test_kernel_assert_access_scoped, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_SCOPED },
1164 { test_kernel_read, &test_var, sizeof(test_var), 0 },
1165 },
1166 };
1167 struct expect_report expect_start2 = {
1168 .access = { expect_start1.access[0], expect_start1.access[0] },
1169 };
1170 struct expect_report expect_inscope = {
1171 .access = {
1172 { test_enter_scope, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_SCOPED },
1173 { test_kernel_read, &test_var, sizeof(test_var), 0 },
1174 },
1175 };
1176 bool match_expect_start = false;
1177 bool match_expect_inscope = false;
1178
1179 begin_test_checks(test_kernel_assert_access_scoped, test_kernel_read);
1180 end_time += msecs_to_jiffies(1000); /* This test requires a bit more time. */
1181 do {
1182 match_expect_start |= report_matches(&expect_start1) || report_matches(&expect_start2);
1183 match_expect_inscope |= report_matches(&expect_inscope);
1184 } while (!end_test_checks(match_expect_inscope));
1185 KUNIT_EXPECT_TRUE(test, match_expect_start);
1186 KUNIT_EXPECT_FALSE(test, match_expect_inscope);
1187 }
1188
1189 /*
1190 * jiffies is special (declared to be volatile) and its accesses are typically
1191 * not marked; this test ensures that the compiler nor KCSAN gets confused about
1192 * jiffies's declaration on different architectures.
1193 */
1194 __no_kcsan
1195 static void test_jiffies_noreport(struct kunit *test)
1196 {
1197 bool match_never = false;
1198
1199 begin_test_checks(test_kernel_jiffies_reader, test_kernel_jiffies_reader);
1200 do {
1201 match_never = report_available();
1202 } while (!end_test_checks(match_never));
1203 KUNIT_EXPECT_FALSE(test, match_never);
1204 }
1205
1206 /* Test that racing accesses in seqlock critical sections are not reported. */
1207 __no_kcsan
1208 static void test_seqlock_noreport(struct kunit *test)
1209 {
1210 bool match_never = false;
1211
1212 begin_test_checks(test_kernel_seqlock_reader, test_kernel_seqlock_writer);
1213 do {
1214 match_never = report_available();
1215 } while (!end_test_checks(match_never));
1216 KUNIT_EXPECT_FALSE(test, match_never);
1217 }
1218
1219 /*
1220 * Test atomic builtins work and required instrumentation functions exist. We
1221 * also test that KCSAN understands they're atomic by racing with them via
1222 * test_kernel_atomic_builtins(), and expect no reports.
1223 *
1224 * The atomic builtins _SHOULD NOT_ be used in normal kernel code!
1225 */
1226 static void test_atomic_builtins(struct kunit *test)
1227 {
1228 bool match_never = false;
1229
1230 begin_test_checks(test_kernel_atomic_builtins, test_kernel_atomic_builtins);
1231 do {
1232 long tmp;
1233
1234 kcsan_enable_current();
1235
1236 __atomic_store_n(&test_var, 42L, __ATOMIC_RELAXED);
1237 KUNIT_EXPECT_EQ(test, 42L, __atomic_load_n(&test_var, __ATOMIC_RELAXED));
1238
1239 KUNIT_EXPECT_EQ(test, 42L, __atomic_exchange_n(&test_var, 20, __ATOMIC_RELAXED));
1240 KUNIT_EXPECT_EQ(test, 20L, test_var);
1241
1242 tmp = 20L;
1243 KUNIT_EXPECT_TRUE(test, __atomic_compare_exchange_n(&test_var, &tmp, 30L,
1244 0, __ATOMIC_RELAXED,
1245 __ATOMIC_RELAXED));
1246 KUNIT_EXPECT_EQ(test, tmp, 20L);
1247 KUNIT_EXPECT_EQ(test, test_var, 30L);
1248 KUNIT_EXPECT_FALSE(test, __atomic_compare_exchange_n(&test_var, &tmp, 40L,
1249 1, __ATOMIC_RELAXED,
1250 __ATOMIC_RELAXED));
1251 KUNIT_EXPECT_EQ(test, tmp, 30L);
1252 KUNIT_EXPECT_EQ(test, test_var, 30L);
1253
1254 KUNIT_EXPECT_EQ(test, 30L, __atomic_fetch_add(&test_var, 1, __ATOMIC_RELAXED));
1255 KUNIT_EXPECT_EQ(test, 31L, __atomic_fetch_sub(&test_var, 1, __ATOMIC_RELAXED));
1256 KUNIT_EXPECT_EQ(test, 30L, __atomic_fetch_and(&test_var, 0xf, __ATOMIC_RELAXED));
1257 KUNIT_EXPECT_EQ(test, 14L, __atomic_fetch_xor(&test_var, 0xf, __ATOMIC_RELAXED));
1258 KUNIT_EXPECT_EQ(test, 1L, __atomic_fetch_or(&test_var, 0xf0, __ATOMIC_RELAXED));
1259 KUNIT_EXPECT_EQ(test, 241L, __atomic_fetch_nand(&test_var, 0xf, __ATOMIC_RELAXED));
1260 KUNIT_EXPECT_EQ(test, -2L, test_var);
1261
1262 __atomic_thread_fence(__ATOMIC_SEQ_CST);
1263 __atomic_signal_fence(__ATOMIC_SEQ_CST);
1264
1265 kcsan_disable_current();
1266
1267 match_never = report_available();
1268 } while (!end_test_checks(match_never));
1269 KUNIT_EXPECT_FALSE(test, match_never);
1270 }
1271
1272 __no_kcsan
1273 static void test_1bit_value_change(struct kunit *test)
1274 {
1275 struct expect_report expect = {
1276 .access = {
1277 { test_kernel_read, &test_var, sizeof(test_var), 0 },
1278 { test_kernel_xor_1bit, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1279 },
1280 };
1281 bool match = false;
1282
1283 begin_test_checks(test_kernel_read, test_kernel_xor_1bit);
1284 do {
1285 match = IS_ENABLED(CONFIG_KCSAN_PERMISSIVE)
1286 ? report_available()
1287 : report_matches(&expect);
1288 } while (!end_test_checks(match));
1289 if (IS_ENABLED(CONFIG_KCSAN_PERMISSIVE))
1290 KUNIT_EXPECT_FALSE(test, match);
1291 else
1292 KUNIT_EXPECT_TRUE(test, match);
1293 }
1294
1295 __no_kcsan
1296 static void test_correct_barrier(struct kunit *test)
1297 {
1298 struct expect_report expect = {
1299 .access = {
1300 { test_kernel_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1301 { test_kernel_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
1302 },
1303 };
1304 bool match_expect = false;
1305
1306 test_struct.val[0] = 0; /* init unlocked */
1307 begin_test_checks(test_kernel_with_memorder, test_kernel_with_memorder);
1308 do {
1309 match_expect = report_matches_any_reordered(&expect);
1310 } while (!end_test_checks(match_expect));
1311 KUNIT_EXPECT_FALSE(test, match_expect);
1312 }
1313
1314 __no_kcsan
1315 static void test_missing_barrier(struct kunit *test)
1316 {
1317 struct expect_report expect = {
1318 .access = {
1319 { test_kernel_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1320 { test_kernel_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
1321 },
1322 };
1323 bool match_expect = false;
1324
1325 test_struct.val[0] = 0; /* init unlocked */
1326 begin_test_checks(test_kernel_wrong_memorder, test_kernel_wrong_memorder);
1327 do {
1328 match_expect = report_matches_any_reordered(&expect);
1329 } while (!end_test_checks(match_expect));
1330 if (IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY))
1331 KUNIT_EXPECT_TRUE(test, match_expect);
1332 else
1333 KUNIT_EXPECT_FALSE(test, match_expect);
1334 }
1335
1336 __no_kcsan
1337 static void test_atomic_builtins_correct_barrier(struct kunit *test)
1338 {
1339 struct expect_report expect = {
1340 .access = {
1341 { test_kernel_atomic_builtin_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1342 { test_kernel_atomic_builtin_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
1343 },
1344 };
1345 bool match_expect = false;
1346
1347 test_struct.val[0] = 0; /* init unlocked */
1348 begin_test_checks(test_kernel_atomic_builtin_with_memorder,
1349 test_kernel_atomic_builtin_with_memorder);
1350 do {
1351 match_expect = report_matches_any_reordered(&expect);
1352 } while (!end_test_checks(match_expect));
1353 KUNIT_EXPECT_FALSE(test, match_expect);
1354 }
1355
1356 __no_kcsan
1357 static void test_atomic_builtins_missing_barrier(struct kunit *test)
1358 {
1359 struct expect_report expect = {
1360 .access = {
1361 { test_kernel_atomic_builtin_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1362 { test_kernel_atomic_builtin_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
1363 },
1364 };
1365 bool match_expect = false;
1366
1367 test_struct.val[0] = 0; /* init unlocked */
1368 begin_test_checks(test_kernel_atomic_builtin_wrong_memorder,
1369 test_kernel_atomic_builtin_wrong_memorder);
1370 do {
1371 match_expect = report_matches_any_reordered(&expect);
1372 } while (!end_test_checks(match_expect));
1373 if (IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY))
1374 KUNIT_EXPECT_TRUE(test, match_expect);
1375 else
1376 KUNIT_EXPECT_FALSE(test, match_expect);
1377 }
1378
1379 /*
1380 * Generate thread counts for all test cases. Values generated are in interval
1381 * [2, 5] followed by exponentially increasing thread counts from 8 to 32.
1382 *
1383 * The thread counts are chosen to cover potentially interesting boundaries and
1384 * corner cases (2 to 5), and then stress the system with larger counts.
1385 */
1386 static const void *nthreads_gen_params(const void *prev, char *desc)
1387 {
1388 long nthreads = (long)prev;
1389
1390 if (nthreads < 0 || nthreads >= 32)
1391 nthreads = 0; /* stop */
1392 else if (!nthreads)
1393 nthreads = 2; /* initial value */
1394 else if (nthreads < 5)
1395 nthreads++;
1396 else if (nthreads == 5)
1397 nthreads = 8;
1398 else
1399 nthreads *= 2;
1400
1401 if (!preempt_model_preemptible() ||
1402 !IS_ENABLED(CONFIG_KCSAN_INTERRUPT_WATCHER)) {
1403 /*
1404 * Without any preemption, keep 2 CPUs free for other tasks, one
1405 * of which is the main test case function checking for
1406 * completion or failure.
1407 */
1408 const long min_unused_cpus = preempt_model_none() ? 2 : 0;
1409 const long min_required_cpus = 2 + min_unused_cpus;
1410
1411 if (num_online_cpus() < min_required_cpus) {
1412 pr_err_once("Too few online CPUs (%u < %ld) for test\n",
1413 num_online_cpus(), min_required_cpus);
1414 nthreads = 0;
1415 } else if (nthreads >= num_online_cpus() - min_unused_cpus) {
1416 /* Use negative value to indicate last param. */
1417 nthreads = -(num_online_cpus() - min_unused_cpus);
1418 pr_warn_once("Limiting number of threads to %ld (only %d online CPUs)\n",
1419 -nthreads, num_online_cpus());
1420 }
1421 }
1422
1423 snprintf(desc, KUNIT_PARAM_DESC_SIZE, "threads=%ld", abs(nthreads));
1424 return (void *)nthreads;
1425 }
1426
1427 #define KCSAN_KUNIT_CASE(test_name) KUNIT_CASE_PARAM(test_name, nthreads_gen_params)
1428 static struct kunit_case kcsan_test_cases[] = {
1429 KUNIT_CASE(test_barrier_nothreads),
1430 KCSAN_KUNIT_CASE(test_basic),
1431 KCSAN_KUNIT_CASE(test_concurrent_races),
1432 KCSAN_KUNIT_CASE(test_novalue_change),
1433 KCSAN_KUNIT_CASE(test_novalue_change_exception),
1434 KCSAN_KUNIT_CASE(test_unknown_origin),
1435 KCSAN_KUNIT_CASE(test_write_write_assume_atomic),
1436 KCSAN_KUNIT_CASE(test_write_write_struct),
1437 KCSAN_KUNIT_CASE(test_write_write_struct_part),
1438 KCSAN_KUNIT_CASE(test_read_atomic_write_atomic),
1439 KCSAN_KUNIT_CASE(test_read_plain_atomic_write),
1440 KCSAN_KUNIT_CASE(test_read_plain_atomic_rmw),
1441 KCSAN_KUNIT_CASE(test_zero_size_access),
1442 KCSAN_KUNIT_CASE(test_data_race),
1443 KCSAN_KUNIT_CASE(test_data_racy_qualifier),
1444 KCSAN_KUNIT_CASE(test_assert_exclusive_writer),
1445 KCSAN_KUNIT_CASE(test_assert_exclusive_access),
1446 KCSAN_KUNIT_CASE(test_assert_exclusive_access_writer),
1447 KCSAN_KUNIT_CASE(test_assert_exclusive_bits_change),
1448 KCSAN_KUNIT_CASE(test_assert_exclusive_bits_nochange),
1449 KCSAN_KUNIT_CASE(test_assert_exclusive_writer_scoped),
1450 KCSAN_KUNIT_CASE(test_assert_exclusive_access_scoped),
1451 KCSAN_KUNIT_CASE(test_jiffies_noreport),
1452 KCSAN_KUNIT_CASE(test_seqlock_noreport),
1453 KCSAN_KUNIT_CASE(test_atomic_builtins),
1454 KCSAN_KUNIT_CASE(test_1bit_value_change),
1455 KCSAN_KUNIT_CASE(test_correct_barrier),
1456 KCSAN_KUNIT_CASE(test_missing_barrier),
1457 KCSAN_KUNIT_CASE(test_atomic_builtins_correct_barrier),
1458 KCSAN_KUNIT_CASE(test_atomic_builtins_missing_barrier),
1459 {},
1460 };
1461
1462 /* ===== End test cases ===== */
1463
1464 /* Concurrent accesses from interrupts. */
1465 __no_kcsan
1466 static void access_thread_timer(struct timer_list *timer)
1467 {
1468 static atomic_t cnt = ATOMIC_INIT(0);
1469 unsigned int idx;
1470 void (*func)(void);
1471
1472 idx = (unsigned int)atomic_inc_return(&cnt) % ARRAY_SIZE(access_kernels);
1473 /* Acquire potential initialization. */
1474 func = smp_load_acquire(&access_kernels[idx]);
1475 if (func)
1476 func();
1477 }
1478
1479 /* The main loop for each thread. */
1480 __no_kcsan
1481 static int access_thread(void *arg)
1482 {
1483 struct timer_list timer;
1484 unsigned int cnt = 0;
1485 unsigned int idx;
1486 void (*func)(void);
1487
1488 timer_setup_on_stack(&timer, access_thread_timer, 0);
1489 do {
1490 might_sleep();
1491
1492 if (!timer_pending(&timer))
1493 mod_timer(&timer, jiffies + 1);
1494 else {
1495 /* Iterate through all kernels. */
1496 idx = cnt++ % ARRAY_SIZE(access_kernels);
1497 /* Acquire potential initialization. */
1498 func = smp_load_acquire(&access_kernels[idx]);
1499 if (func)
1500 func();
1501 }
1502 } while (!torture_must_stop());
1503 del_timer_sync(&timer);
1504 destroy_timer_on_stack(&timer);
1505
1506 torture_kthread_stopping("access_thread");
1507 return 0;
1508 }
1509
1510 __no_kcsan
1511 static int test_init(struct kunit *test)
1512 {
1513 unsigned long flags;
1514 int nthreads;
1515 int i;
1516
1517 spin_lock_irqsave(&observed.lock, flags);
1518 for (i = 0; i < ARRAY_SIZE(observed.lines); ++i)
1519 observed.lines[i][0] = '\0';
1520 observed.nlines = 0;
1521 spin_unlock_irqrestore(&observed.lock, flags);
1522
1523 if (strstr(test->name, "nothreads"))
1524 return 0;
1525
1526 if (!torture_init_begin((char *)test->name, 1))
1527 return -EBUSY;
1528
1529 if (WARN_ON(threads))
1530 goto err;
1531
1532 for (i = 0; i < ARRAY_SIZE(access_kernels); ++i) {
1533 if (WARN_ON(access_kernels[i]))
1534 goto err;
1535 }
1536
1537 nthreads = abs((long)test->param_value);
1538 if (WARN_ON(!nthreads))
1539 goto err;
1540
1541 threads = kcalloc(nthreads + 1, sizeof(struct task_struct *), GFP_KERNEL);
1542 if (WARN_ON(!threads))
1543 goto err;
1544
1545 threads[nthreads] = NULL;
1546 for (i = 0; i < nthreads; ++i) {
1547 if (torture_create_kthread(access_thread, NULL, threads[i]))
1548 goto err;
1549 }
1550
1551 torture_init_end();
1552
1553 return 0;
1554
1555 err:
1556 kfree(threads);
1557 threads = NULL;
1558 torture_init_end();
1559 return -EINVAL;
1560 }
1561
1562 __no_kcsan
1563 static void test_exit(struct kunit *test)
1564 {
1565 struct task_struct **stop_thread;
1566 int i;
1567
1568 if (strstr(test->name, "nothreads"))
1569 return;
1570
1571 if (torture_cleanup_begin())
1572 return;
1573
1574 for (i = 0; i < ARRAY_SIZE(access_kernels); ++i)
1575 WRITE_ONCE(access_kernels[i], NULL);
1576
1577 if (threads) {
1578 for (stop_thread = threads; *stop_thread; stop_thread++)
1579 torture_stop_kthread(reader_thread, *stop_thread);
1580
1581 kfree(threads);
1582 threads = NULL;
1583 }
1584
1585 torture_cleanup_end();
1586 }
1587
1588 __no_kcsan
1589 static void register_tracepoints(void)
1590 {
1591 register_trace_console(probe_console, NULL);
1592 }
1593
1594 __no_kcsan
1595 static void unregister_tracepoints(void)
1596 {
1597 unregister_trace_console(probe_console, NULL);
1598 }
1599
1600 static int kcsan_suite_init(struct kunit_suite *suite)
1601 {
1602 register_tracepoints();
1603 return 0;
1604 }
1605
1606 static void kcsan_suite_exit(struct kunit_suite *suite)
1607 {
1608 unregister_tracepoints();
1609 tracepoint_synchronize_unregister();
1610 }
1611
1612 static struct kunit_suite kcsan_test_suite = {
1613 .name = "kcsan",
1614 .test_cases = kcsan_test_cases,
1615 .init = test_init,
1616 .exit = test_exit,
1617 .suite_init = kcsan_suite_init,
1618 .suite_exit = kcsan_suite_exit,
1619 };
1620
1621 kunit_test_suites(&kcsan_test_suite);
1622
1623 MODULE_DESCRIPTION("KCSAN test suite");
1624 MODULE_LICENSE("GPL v2");
1625 MODULE_AUTHOR("Marco Elver <elver@google.com>");
1626
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