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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". */
47static void (*access_kernels[2])(void);
48
49static struct task_struct **threads; /* Lists of threads. */
50static unsigned long end_time; /* End time of test. */
51
52/* Report as observed from console. */
53static 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. */
62static __no_kcsan inline void
63begin_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. */
79static __no_kcsan inline bool
80end_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
97static 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
132out:
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
139static 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. */
145struct 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
157static 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])));
258out:
259 spin_unlock_irqrestore(&observed.lock, flags);
260 kfree(expect);
261 return ret;
262}
263
264static __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
283static 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
300static long test_sink;
301static long test_var;
302/* @test_array should be large enough to fall into multiple watchpoint slots. */
303static long test_array[3 * PAGE_SIZE / sizeof(long)];
304static struct {
305 long val[8];
306} test_struct;
307static DEFINE_SEQLOCK(test_seqlock);
308static DEFINE_SPINLOCK(test_spinlock);
309static DEFINE_MUTEX(test_mutex);
310
311/*
312 * Helper to avoid compiler optimizing out reads, and to generate source values
313 * for writes.
314 */
315__no_kcsan
316static noinline void sink_value(long v) { WRITE_ONCE(test_sink, v); }
317
318/*
319 * Generates a delay and some accesses that enter the runtime but do not produce
320 * data races.
321 */
322static noinline void test_delay(int iter)
323{
324 while (iter--)
325 sink_value(READ_ONCE(test_sink));
326}
327
328static noinline void test_kernel_read(void) { sink_value(test_var); }
329
330static noinline void test_kernel_write(void)
331{
332 test_var = READ_ONCE_NOCHECK(test_sink) + 1;
333}
334
335static noinline void test_kernel_write_nochange(void) { test_var = 42; }
336
337/* Suffixed by value-change exception filter. */
338static noinline void test_kernel_write_nochange_rcu(void) { test_var = 42; }
339
340static noinline void test_kernel_read_atomic(void)
341{
342 sink_value(READ_ONCE(test_var));
343}
344
345static noinline void test_kernel_write_atomic(void)
346{
347 WRITE_ONCE(test_var, READ_ONCE_NOCHECK(test_sink) + 1);
348}
349
350static noinline void test_kernel_atomic_rmw(void)
351{
352 /* Use builtin, so we can set up the "bad" atomic/non-atomic scenario. */
353 __atomic_fetch_add(&test_var, 1, __ATOMIC_RELAXED);
354}
355
356__no_kcsan
357static noinline void test_kernel_write_uninstrumented(void) { test_var++; }
358
359static noinline void test_kernel_data_race(void) { data_race(test_var++); }
360
361static noinline void test_kernel_assert_writer(void)
362{
363 ASSERT_EXCLUSIVE_WRITER(test_var);
364}
365
366static noinline void test_kernel_assert_access(void)
367{
368 ASSERT_EXCLUSIVE_ACCESS(test_var);
369}
370
371#define TEST_CHANGE_BITS 0xff00ff00
372
373static noinline void test_kernel_change_bits(void)
374{
375 if (IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) {
376 /*
377 * Avoid race of unknown origin for this test, just pretend they
378 * are atomic.
379 */
380 kcsan_nestable_atomic_begin();
381 test_var ^= TEST_CHANGE_BITS;
382 kcsan_nestable_atomic_end();
383 } else
384 WRITE_ONCE(test_var, READ_ONCE(test_var) ^ TEST_CHANGE_BITS);
385}
386
387static noinline void test_kernel_assert_bits_change(void)
388{
389 ASSERT_EXCLUSIVE_BITS(test_var, TEST_CHANGE_BITS);
390}
391
392static noinline void test_kernel_assert_bits_nochange(void)
393{
394 ASSERT_EXCLUSIVE_BITS(test_var, ~TEST_CHANGE_BITS);
395}
396
397/*
398 * Scoped assertions do trigger anywhere in scope. However, the report should
399 * still only point at the start of the scope.
400 */
401static noinline void test_enter_scope(void)
402{
403 int x = 0;
404
405 /* Unrelated accesses to scoped assert. */
406 READ_ONCE(test_sink);
407 kcsan_check_read(&x, sizeof(x));
408}
409
410static noinline void test_kernel_assert_writer_scoped(void)
411{
412 ASSERT_EXCLUSIVE_WRITER_SCOPED(test_var);
413 test_enter_scope();
414}
415
416static noinline void test_kernel_assert_access_scoped(void)
417{
418 ASSERT_EXCLUSIVE_ACCESS_SCOPED(test_var);
419 test_enter_scope();
420}
421
422static noinline void test_kernel_rmw_array(void)
423{
424 int i;
425
426 for (i = 0; i < ARRAY_SIZE(test_array); ++i)
427 test_array[i]++;
428}
429
430static noinline void test_kernel_write_struct(void)
431{
432 kcsan_check_write(&test_struct, sizeof(test_struct));
433 kcsan_disable_current();
434 test_struct.val[3]++; /* induce value change */
435 kcsan_enable_current();
436}
437
438static noinline void test_kernel_write_struct_part(void)
439{
440 test_struct.val[3] = 42;
441}
442
443static noinline void test_kernel_read_struct_zero_size(void)
444{
445 kcsan_check_read(&test_struct.val[3], 0);
446}
447
448static noinline void test_kernel_jiffies_reader(void)
449{
450 sink_value((long)jiffies);
451}
452
453static noinline void test_kernel_seqlock_reader(void)
454{
455 unsigned int seq;
456
457 do {
458 seq = read_seqbegin(&test_seqlock);
459 sink_value(test_var);
460 } while (read_seqretry(&test_seqlock, seq));
461}
462
463static noinline void test_kernel_seqlock_writer(void)
464{
465 unsigned long flags;
466
467 write_seqlock_irqsave(&test_seqlock, flags);
468 test_var++;
469 write_sequnlock_irqrestore(&test_seqlock, flags);
470}
471
472static noinline void test_kernel_atomic_builtins(void)
473{
474 /*
475 * Generate concurrent accesses, expecting no reports, ensuring KCSAN
476 * treats builtin atomics as actually atomic.
477 */
478 __atomic_load_n(&test_var, __ATOMIC_RELAXED);
479}
480
481static noinline void test_kernel_xor_1bit(void)
482{
483 /* Do not report data races between the read-writes. */
484 kcsan_nestable_atomic_begin();
485 test_var ^= 0x10000;
486 kcsan_nestable_atomic_end();
487}
488
489#define TEST_KERNEL_LOCKED(name, acquire, release) \
490 static noinline void test_kernel_##name(void) \
491 { \
492 long *flag = &test_struct.val[0]; \
493 long v = 0; \
494 if (!(acquire)) \
495 return; \
496 while (v++ < 100) { \
497 test_var++; \
498 barrier(); \
499 } \
500 release; \
501 test_delay(10); \
502 }
503
504TEST_KERNEL_LOCKED(with_memorder,
505 cmpxchg_acquire(flag, 0, 1) == 0,
506 smp_store_release(flag, 0));
507TEST_KERNEL_LOCKED(wrong_memorder,
508 cmpxchg_relaxed(flag, 0, 1) == 0,
509 WRITE_ONCE(*flag, 0));
510TEST_KERNEL_LOCKED(atomic_builtin_with_memorder,
511 __atomic_compare_exchange_n(flag, &v, 1, 0, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED),
512 __atomic_store_n(flag, 0, __ATOMIC_RELEASE));
513TEST_KERNEL_LOCKED(atomic_builtin_wrong_memorder,
514 __atomic_compare_exchange_n(flag, &v, 1, 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED),
515 __atomic_store_n(flag, 0, __ATOMIC_RELAXED));
516
517/* ===== Test cases ===== */
518
519/*
520 * Tests that various barriers have the expected effect on internal state. Not
521 * exhaustive on atomic_t operations. Unlike the selftest, also checks for
522 * too-strict barrier instrumentation; these can be tolerated, because it does
523 * not cause false positives, but at least we should be aware of such cases.
524 */
525static void test_barrier_nothreads(struct kunit *test)
526{
527#ifdef CONFIG_KCSAN_WEAK_MEMORY
528 struct kcsan_scoped_access *reorder_access = ¤t->kcsan_ctx.reorder_access;
529#else
530 struct kcsan_scoped_access *reorder_access = NULL;
531#endif
532 arch_spinlock_t arch_spinlock = __ARCH_SPIN_LOCK_UNLOCKED;
533 atomic_t dummy;
534
535 KCSAN_TEST_REQUIRES(test, reorder_access != NULL);
536 KCSAN_TEST_REQUIRES(test, IS_ENABLED(CONFIG_SMP));
537
538#define __KCSAN_EXPECT_BARRIER(access_type, barrier, order_before, name) \
539 do { \
540 reorder_access->type = (access_type) | KCSAN_ACCESS_SCOPED; \
541 reorder_access->size = sizeof(test_var); \
542 barrier; \
543 KUNIT_EXPECT_EQ_MSG(test, reorder_access->size, \
544 order_before ? 0 : sizeof(test_var), \
545 "improperly instrumented type=(" #access_type "): " name); \
546 } while (0)
547#define KCSAN_EXPECT_READ_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(0, b, o, #b)
548#define KCSAN_EXPECT_WRITE_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(KCSAN_ACCESS_WRITE, b, o, #b)
549#define KCSAN_EXPECT_RW_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE, b, o, #b)
550
551 /*
552 * Lockdep initialization can strengthen certain locking operations due
553 * to calling into instrumented files; "warm up" our locks.
554 */
555 spin_lock(&test_spinlock);
556 spin_unlock(&test_spinlock);
557 mutex_lock(&test_mutex);
558 mutex_unlock(&test_mutex);
559
560 /* Force creating a valid entry in reorder_access first. */
561 test_var = 0;
562 while (test_var++ < 1000000 && reorder_access->size != sizeof(test_var))
563 __kcsan_check_read(&test_var, sizeof(test_var));
564 KUNIT_ASSERT_EQ(test, reorder_access->size, sizeof(test_var));
565
566 kcsan_nestable_atomic_begin(); /* No watchpoints in called functions. */
567
568 KCSAN_EXPECT_READ_BARRIER(mb(), true);
569 KCSAN_EXPECT_READ_BARRIER(wmb(), false);
570 KCSAN_EXPECT_READ_BARRIER(rmb(), true);
571 KCSAN_EXPECT_READ_BARRIER(smp_mb(), true);
572 KCSAN_EXPECT_READ_BARRIER(smp_wmb(), false);
573 KCSAN_EXPECT_READ_BARRIER(smp_rmb(), true);
574 KCSAN_EXPECT_READ_BARRIER(dma_wmb(), false);
575 KCSAN_EXPECT_READ_BARRIER(dma_rmb(), true);
576 KCSAN_EXPECT_READ_BARRIER(smp_mb__before_atomic(), true);
577 KCSAN_EXPECT_READ_BARRIER(smp_mb__after_atomic(), true);
578 KCSAN_EXPECT_READ_BARRIER(smp_mb__after_spinlock(), true);
579 KCSAN_EXPECT_READ_BARRIER(smp_store_mb(test_var, 0), true);
580 KCSAN_EXPECT_READ_BARRIER(smp_load_acquire(&test_var), false);
581 KCSAN_EXPECT_READ_BARRIER(smp_store_release(&test_var, 0), true);
582 KCSAN_EXPECT_READ_BARRIER(xchg(&test_var, 0), true);
583 KCSAN_EXPECT_READ_BARRIER(xchg_release(&test_var, 0), true);
584 KCSAN_EXPECT_READ_BARRIER(xchg_relaxed(&test_var, 0), false);
585 KCSAN_EXPECT_READ_BARRIER(cmpxchg(&test_var, 0, 0), true);
586 KCSAN_EXPECT_READ_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
587 KCSAN_EXPECT_READ_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
588 KCSAN_EXPECT_READ_BARRIER(atomic_read(&dummy), false);
589 KCSAN_EXPECT_READ_BARRIER(atomic_read_acquire(&dummy), false);
590 KCSAN_EXPECT_READ_BARRIER(atomic_set(&dummy, 0), false);
591 KCSAN_EXPECT_READ_BARRIER(atomic_set_release(&dummy, 0), true);
592 KCSAN_EXPECT_READ_BARRIER(atomic_add(1, &dummy), false);
593 KCSAN_EXPECT_READ_BARRIER(atomic_add_return(1, &dummy), true);
594 KCSAN_EXPECT_READ_BARRIER(atomic_add_return_acquire(1, &dummy), false);
595 KCSAN_EXPECT_READ_BARRIER(atomic_add_return_release(1, &dummy), true);
596 KCSAN_EXPECT_READ_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
597 KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add(1, &dummy), true);
598 KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
599 KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_release(1, &dummy), true);
600 KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
601 KCSAN_EXPECT_READ_BARRIER(test_and_set_bit(0, &test_var), true);
602 KCSAN_EXPECT_READ_BARRIER(test_and_clear_bit(0, &test_var), true);
603 KCSAN_EXPECT_READ_BARRIER(test_and_change_bit(0, &test_var), true);
604 KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock(0, &test_var), true);
605 KCSAN_EXPECT_READ_BARRIER(__clear_bit_unlock(0, &test_var), true);
606 KCSAN_EXPECT_READ_BARRIER(arch_spin_lock(&arch_spinlock), false);
607 KCSAN_EXPECT_READ_BARRIER(arch_spin_unlock(&arch_spinlock), true);
608 KCSAN_EXPECT_READ_BARRIER(spin_lock(&test_spinlock), false);
609 KCSAN_EXPECT_READ_BARRIER(spin_unlock(&test_spinlock), true);
610 KCSAN_EXPECT_READ_BARRIER(mutex_lock(&test_mutex), false);
611 KCSAN_EXPECT_READ_BARRIER(mutex_unlock(&test_mutex), true);
612
613 KCSAN_EXPECT_WRITE_BARRIER(mb(), true);
614 KCSAN_EXPECT_WRITE_BARRIER(wmb(), true);
615 KCSAN_EXPECT_WRITE_BARRIER(rmb(), false);
616 KCSAN_EXPECT_WRITE_BARRIER(smp_mb(), true);
617 KCSAN_EXPECT_WRITE_BARRIER(smp_wmb(), true);
618 KCSAN_EXPECT_WRITE_BARRIER(smp_rmb(), false);
619 KCSAN_EXPECT_WRITE_BARRIER(dma_wmb(), true);
620 KCSAN_EXPECT_WRITE_BARRIER(dma_rmb(), false);
621 KCSAN_EXPECT_WRITE_BARRIER(smp_mb__before_atomic(), true);
622 KCSAN_EXPECT_WRITE_BARRIER(smp_mb__after_atomic(), true);
623 KCSAN_EXPECT_WRITE_BARRIER(smp_mb__after_spinlock(), true);
624 KCSAN_EXPECT_WRITE_BARRIER(smp_store_mb(test_var, 0), true);
625 KCSAN_EXPECT_WRITE_BARRIER(smp_load_acquire(&test_var), false);
626 KCSAN_EXPECT_WRITE_BARRIER(smp_store_release(&test_var, 0), true);
627 KCSAN_EXPECT_WRITE_BARRIER(xchg(&test_var, 0), true);
628 KCSAN_EXPECT_WRITE_BARRIER(xchg_release(&test_var, 0), true);
629 KCSAN_EXPECT_WRITE_BARRIER(xchg_relaxed(&test_var, 0), false);
630 KCSAN_EXPECT_WRITE_BARRIER(cmpxchg(&test_var, 0, 0), true);
631 KCSAN_EXPECT_WRITE_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
632 KCSAN_EXPECT_WRITE_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
633 KCSAN_EXPECT_WRITE_BARRIER(atomic_read(&dummy), false);
634 KCSAN_EXPECT_WRITE_BARRIER(atomic_read_acquire(&dummy), false);
635 KCSAN_EXPECT_WRITE_BARRIER(atomic_set(&dummy, 0), false);
636 KCSAN_EXPECT_WRITE_BARRIER(atomic_set_release(&dummy, 0), true);
637 KCSAN_EXPECT_WRITE_BARRIER(atomic_add(1, &dummy), false);
638 KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return(1, &dummy), true);
639 KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_acquire(1, &dummy), false);
640 KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_release(1, &dummy), true);
641 KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
642 KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add(1, &dummy), true);
643 KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
644 KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_release(1, &dummy), true);
645 KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
646 KCSAN_EXPECT_WRITE_BARRIER(test_and_set_bit(0, &test_var), true);
647 KCSAN_EXPECT_WRITE_BARRIER(test_and_clear_bit(0, &test_var), true);
648 KCSAN_EXPECT_WRITE_BARRIER(test_and_change_bit(0, &test_var), true);
649 KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock(0, &test_var), true);
650 KCSAN_EXPECT_WRITE_BARRIER(__clear_bit_unlock(0, &test_var), true);
651 KCSAN_EXPECT_WRITE_BARRIER(arch_spin_lock(&arch_spinlock), false);
652 KCSAN_EXPECT_WRITE_BARRIER(arch_spin_unlock(&arch_spinlock), true);
653 KCSAN_EXPECT_WRITE_BARRIER(spin_lock(&test_spinlock), false);
654 KCSAN_EXPECT_WRITE_BARRIER(spin_unlock(&test_spinlock), true);
655 KCSAN_EXPECT_WRITE_BARRIER(mutex_lock(&test_mutex), false);
656 KCSAN_EXPECT_WRITE_BARRIER(mutex_unlock(&test_mutex), true);
657
658 KCSAN_EXPECT_RW_BARRIER(mb(), true);
659 KCSAN_EXPECT_RW_BARRIER(wmb(), true);
660 KCSAN_EXPECT_RW_BARRIER(rmb(), true);
661 KCSAN_EXPECT_RW_BARRIER(smp_mb(), true);
662 KCSAN_EXPECT_RW_BARRIER(smp_wmb(), true);
663 KCSAN_EXPECT_RW_BARRIER(smp_rmb(), true);
664 KCSAN_EXPECT_RW_BARRIER(dma_wmb(), true);
665 KCSAN_EXPECT_RW_BARRIER(dma_rmb(), true);
666 KCSAN_EXPECT_RW_BARRIER(smp_mb__before_atomic(), true);
667 KCSAN_EXPECT_RW_BARRIER(smp_mb__after_atomic(), true);
668 KCSAN_EXPECT_RW_BARRIER(smp_mb__after_spinlock(), true);
669 KCSAN_EXPECT_RW_BARRIER(smp_store_mb(test_var, 0), true);
670 KCSAN_EXPECT_RW_BARRIER(smp_load_acquire(&test_var), false);
671 KCSAN_EXPECT_RW_BARRIER(smp_store_release(&test_var, 0), true);
672 KCSAN_EXPECT_RW_BARRIER(xchg(&test_var, 0), true);
673 KCSAN_EXPECT_RW_BARRIER(xchg_release(&test_var, 0), true);
674 KCSAN_EXPECT_RW_BARRIER(xchg_relaxed(&test_var, 0), false);
675 KCSAN_EXPECT_RW_BARRIER(cmpxchg(&test_var, 0, 0), true);
676 KCSAN_EXPECT_RW_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
677 KCSAN_EXPECT_RW_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
678 KCSAN_EXPECT_RW_BARRIER(atomic_read(&dummy), false);
679 KCSAN_EXPECT_RW_BARRIER(atomic_read_acquire(&dummy), false);
680 KCSAN_EXPECT_RW_BARRIER(atomic_set(&dummy, 0), false);
681 KCSAN_EXPECT_RW_BARRIER(atomic_set_release(&dummy, 0), true);
682 KCSAN_EXPECT_RW_BARRIER(atomic_add(1, &dummy), false);
683 KCSAN_EXPECT_RW_BARRIER(atomic_add_return(1, &dummy), true);
684 KCSAN_EXPECT_RW_BARRIER(atomic_add_return_acquire(1, &dummy), false);
685 KCSAN_EXPECT_RW_BARRIER(atomic_add_return_release(1, &dummy), true);
686 KCSAN_EXPECT_RW_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
687 KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add(1, &dummy), true);
688 KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
689 KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_release(1, &dummy), true);
690 KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
691 KCSAN_EXPECT_RW_BARRIER(test_and_set_bit(0, &test_var), true);
692 KCSAN_EXPECT_RW_BARRIER(test_and_clear_bit(0, &test_var), true);
693 KCSAN_EXPECT_RW_BARRIER(test_and_change_bit(0, &test_var), true);
694 KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock(0, &test_var), true);
695 KCSAN_EXPECT_RW_BARRIER(__clear_bit_unlock(0, &test_var), true);
696 KCSAN_EXPECT_RW_BARRIER(arch_spin_lock(&arch_spinlock), false);
697 KCSAN_EXPECT_RW_BARRIER(arch_spin_unlock(&arch_spinlock), true);
698 KCSAN_EXPECT_RW_BARRIER(spin_lock(&test_spinlock), false);
699 KCSAN_EXPECT_RW_BARRIER(spin_unlock(&test_spinlock), true);
700 KCSAN_EXPECT_RW_BARRIER(mutex_lock(&test_mutex), false);
701 KCSAN_EXPECT_RW_BARRIER(mutex_unlock(&test_mutex), true);
702
703#ifdef clear_bit_unlock_is_negative_byte
704 KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
705 KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
706 KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
707#endif
708 kcsan_nestable_atomic_end();
709}
710
711/* Simple test with normal data race. */
712__no_kcsan
713static 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
744static 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
773static 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
805static 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
831static 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
853static 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
879static 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
901static 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
920static 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
933static 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
954static 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
976static 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
1004static 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__no_kcsan
1016static void test_assert_exclusive_writer(struct kunit *test)
1017{
1018 struct expect_report expect = {
1019 .access = {
1020 { test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1021 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
1022 },
1023 };
1024 bool match_expect = false;
1025
1026 begin_test_checks(test_kernel_assert_writer, test_kernel_write_nochange);
1027 do {
1028 match_expect = report_matches(&expect);
1029 } while (!end_test_checks(match_expect));
1030 KUNIT_EXPECT_TRUE(test, match_expect);
1031}
1032
1033__no_kcsan
1034static void test_assert_exclusive_access(struct kunit *test)
1035{
1036 struct expect_report expect = {
1037 .access = {
1038 { test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
1039 { test_kernel_read, &test_var, sizeof(test_var), 0 },
1040 },
1041 };
1042 bool match_expect = false;
1043
1044 begin_test_checks(test_kernel_assert_access, test_kernel_read);
1045 do {
1046 match_expect = report_matches(&expect);
1047 } while (!end_test_checks(match_expect));
1048 KUNIT_EXPECT_TRUE(test, match_expect);
1049}
1050
1051__no_kcsan
1052static void test_assert_exclusive_access_writer(struct kunit *test)
1053{
1054 struct expect_report expect_access_writer = {
1055 .access = {
1056 { test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
1057 { test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1058 },
1059 };
1060 struct expect_report expect_access_access = {
1061 .access = {
1062 { test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
1063 { test_kernel_assert_access, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE },
1064 },
1065 };
1066 struct expect_report never = {
1067 .access = {
1068 { test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1069 { test_kernel_assert_writer, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1070 },
1071 };
1072 bool match_expect_access_writer = false;
1073 bool match_expect_access_access = false;
1074 bool match_never = false;
1075
1076 begin_test_checks(test_kernel_assert_access, test_kernel_assert_writer);
1077 do {
1078 match_expect_access_writer |= report_matches(&expect_access_writer);
1079 match_expect_access_access |= report_matches(&expect_access_access);
1080 match_never |= report_matches(&never);
1081 } while (!end_test_checks(match_never));
1082 KUNIT_EXPECT_TRUE(test, match_expect_access_writer);
1083 KUNIT_EXPECT_TRUE(test, match_expect_access_access);
1084 KUNIT_EXPECT_FALSE(test, match_never);
1085}
1086
1087__no_kcsan
1088static void test_assert_exclusive_bits_change(struct kunit *test)
1089{
1090 struct expect_report expect = {
1091 .access = {
1092 { test_kernel_assert_bits_change, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT },
1093 { test_kernel_change_bits, &test_var, sizeof(test_var),
1094 KCSAN_ACCESS_WRITE | (IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS) ? 0 : KCSAN_ACCESS_ATOMIC) },
1095 },
1096 };
1097 bool match_expect = false;
1098
1099 begin_test_checks(test_kernel_assert_bits_change, test_kernel_change_bits);
1100 do {
1101 match_expect = report_matches(&expect);
1102 } while (!end_test_checks(match_expect));
1103 KUNIT_EXPECT_TRUE(test, match_expect);
1104}
1105
1106__no_kcsan
1107static void test_assert_exclusive_bits_nochange(struct kunit *test)
1108{
1109 bool match_never = false;
1110
1111 begin_test_checks(test_kernel_assert_bits_nochange, test_kernel_change_bits);
1112 do {
1113 match_never = report_available();
1114 } while (!end_test_checks(match_never));
1115 KUNIT_EXPECT_FALSE(test, match_never);
1116}
1117
1118__no_kcsan
1119static void test_assert_exclusive_writer_scoped(struct kunit *test)
1120{
1121 struct expect_report expect_start = {
1122 .access = {
1123 { test_kernel_assert_writer_scoped, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_SCOPED },
1124 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
1125 },
1126 };
1127 struct expect_report expect_inscope = {
1128 .access = {
1129 { test_enter_scope, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_SCOPED },
1130 { test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
1131 },
1132 };
1133 bool match_expect_start = false;
1134 bool match_expect_inscope = false;
1135
1136 begin_test_checks(test_kernel_assert_writer_scoped, test_kernel_write_nochange);
1137 do {
1138 match_expect_start |= report_matches(&expect_start);
1139 match_expect_inscope |= report_matches(&expect_inscope);
1140 } while (!end_test_checks(match_expect_inscope));
1141 KUNIT_EXPECT_TRUE(test, match_expect_start);
1142 KUNIT_EXPECT_FALSE(test, match_expect_inscope);
1143}
1144
1145__no_kcsan
1146static void test_assert_exclusive_access_scoped(struct kunit *test)
1147{
1148 struct expect_report expect_start1 = {
1149 .access = {
1150 { test_kernel_assert_access_scoped, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_SCOPED },
1151 { test_kernel_read, &test_var, sizeof(test_var), 0 },
1152 },
1153 };
1154 struct expect_report expect_start2 = {
1155 .access = { expect_start1.access[0], expect_start1.access[0] },
1156 };
1157 struct expect_report expect_inscope = {
1158 .access = {
1159 { test_enter_scope, &test_var, sizeof(test_var), KCSAN_ACCESS_ASSERT | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_SCOPED },
1160 { test_kernel_read, &test_var, sizeof(test_var), 0 },
1161 },
1162 };
1163 bool match_expect_start = false;
1164 bool match_expect_inscope = false;
1165
1166 begin_test_checks(test_kernel_assert_access_scoped, test_kernel_read);
1167 end_time += msecs_to_jiffies(1000); /* This test requires a bit more time. */
1168 do {
1169 match_expect_start |= report_matches(&expect_start1) || report_matches(&expect_start2);
1170 match_expect_inscope |= report_matches(&expect_inscope);
1171 } while (!end_test_checks(match_expect_inscope));
1172 KUNIT_EXPECT_TRUE(test, match_expect_start);
1173 KUNIT_EXPECT_FALSE(test, match_expect_inscope);
1174}
1175
1176/*
1177 * jiffies is special (declared to be volatile) and its accesses are typically
1178 * not marked; this test ensures that the compiler nor KCSAN gets confused about
1179 * jiffies's declaration on different architectures.
1180 */
1181__no_kcsan
1182static void test_jiffies_noreport(struct kunit *test)
1183{
1184 bool match_never = false;
1185
1186 begin_test_checks(test_kernel_jiffies_reader, test_kernel_jiffies_reader);
1187 do {
1188 match_never = report_available();
1189 } while (!end_test_checks(match_never));
1190 KUNIT_EXPECT_FALSE(test, match_never);
1191}
1192
1193/* Test that racing accesses in seqlock critical sections are not reported. */
1194__no_kcsan
1195static void test_seqlock_noreport(struct kunit *test)
1196{
1197 bool match_never = false;
1198
1199 begin_test_checks(test_kernel_seqlock_reader, test_kernel_seqlock_writer);
1200 do {
1201 match_never = report_available();
1202 } while (!end_test_checks(match_never));
1203 KUNIT_EXPECT_FALSE(test, match_never);
1204}
1205
1206/*
1207 * Test atomic builtins work and required instrumentation functions exist. We
1208 * also test that KCSAN understands they're atomic by racing with them via
1209 * test_kernel_atomic_builtins(), and expect no reports.
1210 *
1211 * The atomic builtins _SHOULD NOT_ be used in normal kernel code!
1212 */
1213static void test_atomic_builtins(struct kunit *test)
1214{
1215 bool match_never = false;
1216
1217 begin_test_checks(test_kernel_atomic_builtins, test_kernel_atomic_builtins);
1218 do {
1219 long tmp;
1220
1221 kcsan_enable_current();
1222
1223 __atomic_store_n(&test_var, 42L, __ATOMIC_RELAXED);
1224 KUNIT_EXPECT_EQ(test, 42L, __atomic_load_n(&test_var, __ATOMIC_RELAXED));
1225
1226 KUNIT_EXPECT_EQ(test, 42L, __atomic_exchange_n(&test_var, 20, __ATOMIC_RELAXED));
1227 KUNIT_EXPECT_EQ(test, 20L, test_var);
1228
1229 tmp = 20L;
1230 KUNIT_EXPECT_TRUE(test, __atomic_compare_exchange_n(&test_var, &tmp, 30L,
1231 0, __ATOMIC_RELAXED,
1232 __ATOMIC_RELAXED));
1233 KUNIT_EXPECT_EQ(test, tmp, 20L);
1234 KUNIT_EXPECT_EQ(test, test_var, 30L);
1235 KUNIT_EXPECT_FALSE(test, __atomic_compare_exchange_n(&test_var, &tmp, 40L,
1236 1, __ATOMIC_RELAXED,
1237 __ATOMIC_RELAXED));
1238 KUNIT_EXPECT_EQ(test, tmp, 30L);
1239 KUNIT_EXPECT_EQ(test, test_var, 30L);
1240
1241 KUNIT_EXPECT_EQ(test, 30L, __atomic_fetch_add(&test_var, 1, __ATOMIC_RELAXED));
1242 KUNIT_EXPECT_EQ(test, 31L, __atomic_fetch_sub(&test_var, 1, __ATOMIC_RELAXED));
1243 KUNIT_EXPECT_EQ(test, 30L, __atomic_fetch_and(&test_var, 0xf, __ATOMIC_RELAXED));
1244 KUNIT_EXPECT_EQ(test, 14L, __atomic_fetch_xor(&test_var, 0xf, __ATOMIC_RELAXED));
1245 KUNIT_EXPECT_EQ(test, 1L, __atomic_fetch_or(&test_var, 0xf0, __ATOMIC_RELAXED));
1246 KUNIT_EXPECT_EQ(test, 241L, __atomic_fetch_nand(&test_var, 0xf, __ATOMIC_RELAXED));
1247 KUNIT_EXPECT_EQ(test, -2L, test_var);
1248
1249 __atomic_thread_fence(__ATOMIC_SEQ_CST);
1250 __atomic_signal_fence(__ATOMIC_SEQ_CST);
1251
1252 kcsan_disable_current();
1253
1254 match_never = report_available();
1255 } while (!end_test_checks(match_never));
1256 KUNIT_EXPECT_FALSE(test, match_never);
1257}
1258
1259__no_kcsan
1260static void test_1bit_value_change(struct kunit *test)
1261{
1262 struct expect_report expect = {
1263 .access = {
1264 { test_kernel_read, &test_var, sizeof(test_var), 0 },
1265 { test_kernel_xor_1bit, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1266 },
1267 };
1268 bool match = false;
1269
1270 begin_test_checks(test_kernel_read, test_kernel_xor_1bit);
1271 do {
1272 match = IS_ENABLED(CONFIG_KCSAN_PERMISSIVE)
1273 ? report_available()
1274 : report_matches(&expect);
1275 } while (!end_test_checks(match));
1276 if (IS_ENABLED(CONFIG_KCSAN_PERMISSIVE))
1277 KUNIT_EXPECT_FALSE(test, match);
1278 else
1279 KUNIT_EXPECT_TRUE(test, match);
1280}
1281
1282__no_kcsan
1283static void test_correct_barrier(struct kunit *test)
1284{
1285 struct expect_report expect = {
1286 .access = {
1287 { test_kernel_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1288 { test_kernel_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
1289 },
1290 };
1291 bool match_expect = false;
1292
1293 test_struct.val[0] = 0; /* init unlocked */
1294 begin_test_checks(test_kernel_with_memorder, test_kernel_with_memorder);
1295 do {
1296 match_expect = report_matches_any_reordered(&expect);
1297 } while (!end_test_checks(match_expect));
1298 KUNIT_EXPECT_FALSE(test, match_expect);
1299}
1300
1301__no_kcsan
1302static void test_missing_barrier(struct kunit *test)
1303{
1304 struct expect_report expect = {
1305 .access = {
1306 { test_kernel_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1307 { test_kernel_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
1308 },
1309 };
1310 bool match_expect = false;
1311
1312 test_struct.val[0] = 0; /* init unlocked */
1313 begin_test_checks(test_kernel_wrong_memorder, test_kernel_wrong_memorder);
1314 do {
1315 match_expect = report_matches_any_reordered(&expect);
1316 } while (!end_test_checks(match_expect));
1317 if (IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY))
1318 KUNIT_EXPECT_TRUE(test, match_expect);
1319 else
1320 KUNIT_EXPECT_FALSE(test, match_expect);
1321}
1322
1323__no_kcsan
1324static void test_atomic_builtins_correct_barrier(struct kunit *test)
1325{
1326 struct expect_report expect = {
1327 .access = {
1328 { test_kernel_atomic_builtin_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1329 { test_kernel_atomic_builtin_with_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
1330 },
1331 };
1332 bool match_expect = false;
1333
1334 test_struct.val[0] = 0; /* init unlocked */
1335 begin_test_checks(test_kernel_atomic_builtin_with_memorder,
1336 test_kernel_atomic_builtin_with_memorder);
1337 do {
1338 match_expect = report_matches_any_reordered(&expect);
1339 } while (!end_test_checks(match_expect));
1340 KUNIT_EXPECT_FALSE(test, match_expect);
1341}
1342
1343__no_kcsan
1344static void test_atomic_builtins_missing_barrier(struct kunit *test)
1345{
1346 struct expect_report expect = {
1347 .access = {
1348 { test_kernel_atomic_builtin_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
1349 { test_kernel_atomic_builtin_wrong_memorder, &test_var, sizeof(test_var), __KCSAN_ACCESS_RW(0) },
1350 },
1351 };
1352 bool match_expect = false;
1353
1354 test_struct.val[0] = 0; /* init unlocked */
1355 begin_test_checks(test_kernel_atomic_builtin_wrong_memorder,
1356 test_kernel_atomic_builtin_wrong_memorder);
1357 do {
1358 match_expect = report_matches_any_reordered(&expect);
1359 } while (!end_test_checks(match_expect));
1360 if (IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY))
1361 KUNIT_EXPECT_TRUE(test, match_expect);
1362 else
1363 KUNIT_EXPECT_FALSE(test, match_expect);
1364}
1365
1366/*
1367 * Generate thread counts for all test cases. Values generated are in interval
1368 * [2, 5] followed by exponentially increasing thread counts from 8 to 32.
1369 *
1370 * The thread counts are chosen to cover potentially interesting boundaries and
1371 * corner cases (2 to 5), and then stress the system with larger counts.
1372 */
1373static const void *nthreads_gen_params(const void *prev, char *desc)
1374{
1375 long nthreads = (long)prev;
1376
1377 if (nthreads < 0 || nthreads >= 32)
1378 nthreads = 0; /* stop */
1379 else if (!nthreads)
1380 nthreads = 2; /* initial value */
1381 else if (nthreads < 5)
1382 nthreads++;
1383 else if (nthreads == 5)
1384 nthreads = 8;
1385 else
1386 nthreads *= 2;
1387
1388 if (!preempt_model_preemptible() ||
1389 !IS_ENABLED(CONFIG_KCSAN_INTERRUPT_WATCHER)) {
1390 /*
1391 * Without any preemption, keep 2 CPUs free for other tasks, one
1392 * of which is the main test case function checking for
1393 * completion or failure.
1394 */
1395 const long min_unused_cpus = preempt_model_none() ? 2 : 0;
1396 const long min_required_cpus = 2 + min_unused_cpus;
1397
1398 if (num_online_cpus() < min_required_cpus) {
1399 pr_err_once("Too few online CPUs (%u < %ld) for test\n",
1400 num_online_cpus(), min_required_cpus);
1401 nthreads = 0;
1402 } else if (nthreads >= num_online_cpus() - min_unused_cpus) {
1403 /* Use negative value to indicate last param. */
1404 nthreads = -(num_online_cpus() - min_unused_cpus);
1405 pr_warn_once("Limiting number of threads to %ld (only %d online CPUs)\n",
1406 -nthreads, num_online_cpus());
1407 }
1408 }
1409
1410 snprintf(desc, KUNIT_PARAM_DESC_SIZE, "threads=%ld", abs(nthreads));
1411 return (void *)nthreads;
1412}
1413
1414#define KCSAN_KUNIT_CASE(test_name) KUNIT_CASE_PARAM(test_name, nthreads_gen_params)
1415static struct kunit_case kcsan_test_cases[] = {
1416 KUNIT_CASE(test_barrier_nothreads),
1417 KCSAN_KUNIT_CASE(test_basic),
1418 KCSAN_KUNIT_CASE(test_concurrent_races),
1419 KCSAN_KUNIT_CASE(test_novalue_change),
1420 KCSAN_KUNIT_CASE(test_novalue_change_exception),
1421 KCSAN_KUNIT_CASE(test_unknown_origin),
1422 KCSAN_KUNIT_CASE(test_write_write_assume_atomic),
1423 KCSAN_KUNIT_CASE(test_write_write_struct),
1424 KCSAN_KUNIT_CASE(test_write_write_struct_part),
1425 KCSAN_KUNIT_CASE(test_read_atomic_write_atomic),
1426 KCSAN_KUNIT_CASE(test_read_plain_atomic_write),
1427 KCSAN_KUNIT_CASE(test_read_plain_atomic_rmw),
1428 KCSAN_KUNIT_CASE(test_zero_size_access),
1429 KCSAN_KUNIT_CASE(test_data_race),
1430 KCSAN_KUNIT_CASE(test_assert_exclusive_writer),
1431 KCSAN_KUNIT_CASE(test_assert_exclusive_access),
1432 KCSAN_KUNIT_CASE(test_assert_exclusive_access_writer),
1433 KCSAN_KUNIT_CASE(test_assert_exclusive_bits_change),
1434 KCSAN_KUNIT_CASE(test_assert_exclusive_bits_nochange),
1435 KCSAN_KUNIT_CASE(test_assert_exclusive_writer_scoped),
1436 KCSAN_KUNIT_CASE(test_assert_exclusive_access_scoped),
1437 KCSAN_KUNIT_CASE(test_jiffies_noreport),
1438 KCSAN_KUNIT_CASE(test_seqlock_noreport),
1439 KCSAN_KUNIT_CASE(test_atomic_builtins),
1440 KCSAN_KUNIT_CASE(test_1bit_value_change),
1441 KCSAN_KUNIT_CASE(test_correct_barrier),
1442 KCSAN_KUNIT_CASE(test_missing_barrier),
1443 KCSAN_KUNIT_CASE(test_atomic_builtins_correct_barrier),
1444 KCSAN_KUNIT_CASE(test_atomic_builtins_missing_barrier),
1445 {},
1446};
1447
1448/* ===== End test cases ===== */
1449
1450/* Concurrent accesses from interrupts. */
1451__no_kcsan
1452static void access_thread_timer(struct timer_list *timer)
1453{
1454 static atomic_t cnt = ATOMIC_INIT(0);
1455 unsigned int idx;
1456 void (*func)(void);
1457
1458 idx = (unsigned int)atomic_inc_return(&cnt) % ARRAY_SIZE(access_kernels);
1459 /* Acquire potential initialization. */
1460 func = smp_load_acquire(&access_kernels[idx]);
1461 if (func)
1462 func();
1463}
1464
1465/* The main loop for each thread. */
1466__no_kcsan
1467static int access_thread(void *arg)
1468{
1469 struct timer_list timer;
1470 unsigned int cnt = 0;
1471 unsigned int idx;
1472 void (*func)(void);
1473
1474 timer_setup_on_stack(&timer, access_thread_timer, 0);
1475 do {
1476 might_sleep();
1477
1478 if (!timer_pending(&timer))
1479 mod_timer(&timer, jiffies + 1);
1480 else {
1481 /* Iterate through all kernels. */
1482 idx = cnt++ % ARRAY_SIZE(access_kernels);
1483 /* Acquire potential initialization. */
1484 func = smp_load_acquire(&access_kernels[idx]);
1485 if (func)
1486 func();
1487 }
1488 } while (!torture_must_stop());
1489 del_timer_sync(&timer);
1490 destroy_timer_on_stack(&timer);
1491
1492 torture_kthread_stopping("access_thread");
1493 return 0;
1494}
1495
1496__no_kcsan
1497static int test_init(struct kunit *test)
1498{
1499 unsigned long flags;
1500 int nthreads;
1501 int i;
1502
1503 spin_lock_irqsave(&observed.lock, flags);
1504 for (i = 0; i < ARRAY_SIZE(observed.lines); ++i)
1505 observed.lines[i][0] = '\0';
1506 observed.nlines = 0;
1507 spin_unlock_irqrestore(&observed.lock, flags);
1508
1509 if (strstr(test->name, "nothreads"))
1510 return 0;
1511
1512 if (!torture_init_begin((char *)test->name, 1))
1513 return -EBUSY;
1514
1515 if (WARN_ON(threads))
1516 goto err;
1517
1518 for (i = 0; i < ARRAY_SIZE(access_kernels); ++i) {
1519 if (WARN_ON(access_kernels[i]))
1520 goto err;
1521 }
1522
1523 nthreads = abs((long)test->param_value);
1524 if (WARN_ON(!nthreads))
1525 goto err;
1526
1527 threads = kcalloc(nthreads + 1, sizeof(struct task_struct *), GFP_KERNEL);
1528 if (WARN_ON(!threads))
1529 goto err;
1530
1531 threads[nthreads] = NULL;
1532 for (i = 0; i < nthreads; ++i) {
1533 if (torture_create_kthread(access_thread, NULL, threads[i]))
1534 goto err;
1535 }
1536
1537 torture_init_end();
1538
1539 return 0;
1540
1541err:
1542 kfree(threads);
1543 threads = NULL;
1544 torture_init_end();
1545 return -EINVAL;
1546}
1547
1548__no_kcsan
1549static void test_exit(struct kunit *test)
1550{
1551 struct task_struct **stop_thread;
1552 int i;
1553
1554 if (strstr(test->name, "nothreads"))
1555 return;
1556
1557 if (torture_cleanup_begin())
1558 return;
1559
1560 for (i = 0; i < ARRAY_SIZE(access_kernels); ++i)
1561 WRITE_ONCE(access_kernels[i], NULL);
1562
1563 if (threads) {
1564 for (stop_thread = threads; *stop_thread; stop_thread++)
1565 torture_stop_kthread(reader_thread, *stop_thread);
1566
1567 kfree(threads);
1568 threads = NULL;
1569 }
1570
1571 torture_cleanup_end();
1572}
1573
1574__no_kcsan
1575static void register_tracepoints(struct tracepoint *tp, void *ignore)
1576{
1577 check_trace_callback_type_console(probe_console);
1578 if (!strcmp(tp->name, "console"))
1579 WARN_ON(tracepoint_probe_register(tp, probe_console, NULL));
1580}
1581
1582__no_kcsan
1583static void unregister_tracepoints(struct tracepoint *tp, void *ignore)
1584{
1585 if (!strcmp(tp->name, "console"))
1586 tracepoint_probe_unregister(tp, probe_console, NULL);
1587}
1588
1589static int kcsan_suite_init(struct kunit_suite *suite)
1590{
1591 /*
1592 * Because we want to be able to build the test as a module, we need to
1593 * iterate through all known tracepoints, since the static registration
1594 * won't work here.
1595 */
1596 for_each_kernel_tracepoint(register_tracepoints, NULL);
1597 return 0;
1598}
1599
1600static void kcsan_suite_exit(struct kunit_suite *suite)
1601{
1602 for_each_kernel_tracepoint(unregister_tracepoints, NULL);
1603 tracepoint_synchronize_unregister();
1604}
1605
1606static struct kunit_suite kcsan_test_suite = {
1607 .name = "kcsan",
1608 .test_cases = kcsan_test_cases,
1609 .init = test_init,
1610 .exit = test_exit,
1611 .suite_init = kcsan_suite_init,
1612 .suite_exit = kcsan_suite_exit,
1613};
1614
1615kunit_test_suites(&kcsan_test_suite);
1616
1617MODULE_LICENSE("GPL v2");
1618MODULE_AUTHOR("Marco Elver <elver@google.com>");