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kcsan_test.c
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kcsan_test.c
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// SPDX-License-Identifier: GPL-2.0
/*
* KCSAN test with various race scenarious to test runtime behaviour. Since the
* interface with which KCSAN's reports are obtained is via the console, this is
* the output we should verify. For each test case checks the presence (or
* absence) of generated reports. Relies on 'console' tracepoint to capture
* reports as they appear in the kernel log.
*
* Makes use of KUnit for test organization, and the Torture framework for test
* thread control.
*
* Copyright (C) 2020, Google LLC.
* Author: Marco Elver <elver@google.com>
*/
#define pr_fmt(fmt) "kcsan_test: " fmt
#include <kunit/test.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/jiffies.h>
#include <linux/kcsan-checks.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/seqlock.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/torture.h>
#include <linux/tracepoint.h>
#include <linux/types.h>
#include <trace/events/printk.h>
#define KCSAN_TEST_REQUIRES(test, cond) do { \
if (!(cond)) \
kunit_skip((test), "Test requires: " #cond); \
} while (0)
#ifdef CONFIG_CC_HAS_TSAN_COMPOUND_READ_BEFORE_WRITE
#define __KCSAN_ACCESS_RW(alt) (KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE)
#else
#define __KCSAN_ACCESS_RW(alt) (alt)
#endif
/* Points to current test-case memory access "kernels". */
static void (*access_kernels[2])(void);
static struct task_struct **threads; /* Lists of threads. */
static unsigned long end_time; /* End time of test. */
/* Report as observed from console. */
static struct {
spinlock_t lock;
int nlines;
char lines[3][512];
} observed = {
.lock = __SPIN_LOCK_UNLOCKED(observed.lock),
};
/* Setup test checking loop. */
static __no_kcsan inline void
begin_test_checks(void (*func1)(void), void (*func2)(void))
{
kcsan_disable_current();
/*
* Require at least as long as KCSAN_REPORT_ONCE_IN_MS, to ensure at
* least one race is reported.
*/
end_time = jiffies + msecs_to_jiffies(CONFIG_KCSAN_REPORT_ONCE_IN_MS + 500);
/* Signal start; release potential initialization of shared data. */
smp_store_release(&access_kernels[0], func1);
smp_store_release(&access_kernels[1], func2);
}
/* End test checking loop. */
static __no_kcsan inline bool
end_test_checks(bool stop)
{
if (!stop && time_before(jiffies, end_time)) {
/* Continue checking */
might_sleep();
return false;
}
kcsan_enable_current();
return true;
}
/*
* Probe for console output: checks if a race was reported, and obtains observed
* lines of interest.
*/
__no_kcsan
static void probe_console(void *ignore, const char *buf, size_t len)
{
unsigned long flags;
int nlines;
/*
* Note that KCSAN reports under a global lock, so we do not risk the
* possibility of having multiple reports interleaved. If that were the
* case, we'd expect tests to fail.
*/
spin_lock_irqsave(&observed.lock, flags);
nlines = observed.nlines;
if (strnstr(buf, "BUG: KCSAN: ", len) && strnstr(buf, "test_", len)) {
/*
* KCSAN report and related to the test.
*
* The provided @buf is not NUL-terminated; copy no more than
* @len bytes and let strscpy() add the missing NUL-terminator.
*/
strscpy(observed.lines[0], buf, min(len + 1, sizeof(observed.lines[0])));
nlines = 1;
} else if ((nlines == 1 || nlines == 2) && strnstr(buf, "bytes by", len)) {
strscpy(observed.lines[nlines++], buf, min(len + 1, sizeof(observed.lines[0])));
if (strnstr(buf, "race at unknown origin", len)) {
if (WARN_ON(nlines != 2))
goto out;
/* No second line of interest. */
strcpy(observed.lines[nlines++], "<none>");
}
}
out:
WRITE_ONCE(observed.nlines, nlines); /* Publish new nlines. */
spin_unlock_irqrestore(&observed.lock, flags);
}
/* Check if a report related to the test exists. */
__no_kcsan
static bool report_available(void)
{
return READ_ONCE(observed.nlines) == ARRAY_SIZE(observed.lines);
}
/* Report information we expect in a report. */
struct expect_report {
/* Access information of both accesses. */
struct {
void *fn; /* Function pointer to expected function of top frame. */
void *addr; /* Address of access; unchecked if NULL. */
size_t size; /* Size of access; unchecked if @addr is NULL. */
int type; /* Access type, see KCSAN_ACCESS definitions. */
} access[2];
};
/* Check observed report matches information in @r. */
__no_kcsan
static bool __report_matches(const struct expect_report *r)
{
const bool is_assert = (r->access[0].type | r->access[1].type) & KCSAN_ACCESS_ASSERT;
bool ret = false;
unsigned long flags;
typeof(*observed.lines) *expect;
const char *end;
char *cur;
int i;
/* Doubled-checked locking. */
if (!report_available())
return false;
expect = kmalloc(sizeof(observed.lines), GFP_KERNEL);
if (WARN_ON(!expect))
return false;
/* Generate expected report contents. */
/* Title */
cur = expect[0];
end = &expect[0][sizeof(expect[0]) - 1];
cur += scnprintf(cur, end - cur, "BUG: KCSAN: %s in ",
is_assert ? "assert: race" : "data-race");
if (r->access[1].fn) {
char tmp[2][64];
int cmp;
/* Expect lexographically sorted function names in title. */
scnprintf(tmp[0], sizeof(tmp[0]), "%pS", r->access[0].fn);
scnprintf(tmp[1], sizeof(tmp[1]), "%pS", r->access[1].fn);
cmp = strcmp(tmp[0], tmp[1]);
cur += scnprintf(cur, end - cur, "%ps / %ps",
cmp < 0 ? r->access[0].fn : r->access[1].fn,
cmp < 0 ? r->access[1].fn : r->access[0].fn);
} else {
scnprintf(cur, end - cur, "%pS", r->access[0].fn);
/* The exact offset won't match, remove it. */
cur = strchr(expect[0], '+');
if (cur)
*cur = '\0';
}
/* Access 1 */
cur = expect[1];
end = &expect[1][sizeof(expect[1]) - 1];
if (!r->access[1].fn)
cur += scnprintf(cur, end - cur, "race at unknown origin, with ");
/* Access 1 & 2 */
for (i = 0; i < 2; ++i) {
const int ty = r->access[i].type;
const char *const access_type =
(ty & KCSAN_ACCESS_ASSERT) ?
((ty & KCSAN_ACCESS_WRITE) ?
"assert no accesses" :
"assert no writes") :
((ty & KCSAN_ACCESS_WRITE) ?
((ty & KCSAN_ACCESS_COMPOUND) ?
"read-write" :
"write") :
"read");
const bool is_atomic = (ty & KCSAN_ACCESS_ATOMIC);
const bool is_scoped = (ty & KCSAN_ACCESS_SCOPED);
const char *const access_type_aux =
(is_atomic && is_scoped) ? " (marked, reordered)"
: (is_atomic ? " (marked)"
: (is_scoped ? " (reordered)" : ""));
if (i == 1) {
/* Access 2 */
cur = expect[2];
end = &expect[2][sizeof(expect[2]) - 1];
if (!r->access[1].fn) {
/* Dummy string if no second access is available. */
strcpy(cur, "<none>");
break;
}
}
cur += scnprintf(cur, end - cur, "%s%s to ", access_type,
access_type_aux);
if (r->access[i].addr) /* Address is optional. */
cur += scnprintf(cur, end - cur, "0x%px of %zu bytes",
r->access[i].addr, r->access[i].size);
}
spin_lock_irqsave(&observed.lock, flags);
if (!report_available())
goto out; /* A new report is being captured. */
/* Finally match expected output to what we actually observed. */
ret = strstr(observed.lines[0], expect[0]) &&
/* Access info may appear in any order. */
((strstr(observed.lines[1], expect[1]) &&
strstr(observed.lines[2], expect[2])) ||
(strstr(observed.lines[1], expect[2]) &&
strstr(observed.lines[2], expect[1])));
out:
spin_unlock_irqrestore(&observed.lock, flags);
kfree(expect);
return ret;
}
static __always_inline const struct expect_report *
__report_set_scoped(struct expect_report *r, int accesses)
{
BUILD_BUG_ON(accesses > 3);
if (accesses & 1)
r->access[0].type |= KCSAN_ACCESS_SCOPED;
else
r->access[0].type &= ~KCSAN_ACCESS_SCOPED;
if (accesses & 2)
r->access[1].type |= KCSAN_ACCESS_SCOPED;
else
r->access[1].type &= ~KCSAN_ACCESS_SCOPED;
return r;
}
__no_kcsan
static bool report_matches_any_reordered(struct expect_report *r)
{
return __report_matches(__report_set_scoped(r, 0)) ||
__report_matches(__report_set_scoped(r, 1)) ||
__report_matches(__report_set_scoped(r, 2)) ||
__report_matches(__report_set_scoped(r, 3));
}
#ifdef CONFIG_KCSAN_WEAK_MEMORY
/* Due to reordering accesses, any access may appear as "(reordered)". */
#define report_matches report_matches_any_reordered
#else
#define report_matches __report_matches
#endif
/* ===== Test kernels ===== */
static long test_sink;
static long test_var;
/* @test_array should be large enough to fall into multiple watchpoint slots. */
static long test_array[3 * PAGE_SIZE / sizeof(long)];
static struct {
long val[8];
} test_struct;
static DEFINE_SEQLOCK(test_seqlock);
static DEFINE_SPINLOCK(test_spinlock);
static DEFINE_MUTEX(test_mutex);
/*
* Helper to avoid compiler optimizing out reads, and to generate source values
* for writes.
*/
__no_kcsan
static noinline void sink_value(long v) { WRITE_ONCE(test_sink, v); }
/*
* Generates a delay and some accesses that enter the runtime but do not produce
* data races.
*/
static noinline void test_delay(int iter)
{
while (iter--)
sink_value(READ_ONCE(test_sink));
}
static noinline void test_kernel_read(void) { sink_value(test_var); }
static noinline void test_kernel_write(void)
{
test_var = READ_ONCE_NOCHECK(test_sink) + 1;
}
static noinline void test_kernel_write_nochange(void) { test_var = 42; }
/* Suffixed by value-change exception filter. */
static noinline void test_kernel_write_nochange_rcu(void) { test_var = 42; }
static noinline void test_kernel_read_atomic(void)
{
sink_value(READ_ONCE(test_var));
}
static noinline void test_kernel_write_atomic(void)
{
WRITE_ONCE(test_var, READ_ONCE_NOCHECK(test_sink) + 1);
}
static noinline void test_kernel_atomic_rmw(void)
{
/* Use builtin, so we can set up the "bad" atomic/non-atomic scenario. */
__atomic_fetch_add(&test_var, 1, __ATOMIC_RELAXED);
}
__no_kcsan
static noinline void test_kernel_write_uninstrumented(void) { test_var++; }
static noinline void test_kernel_data_race(void) { data_race(test_var++); }
static noinline void test_kernel_assert_writer(void)
{
ASSERT_EXCLUSIVE_WRITER(test_var);
}
static noinline void test_kernel_assert_access(void)
{
ASSERT_EXCLUSIVE_ACCESS(test_var);
}
#define TEST_CHANGE_BITS 0xff00ff00
static noinline void test_kernel_change_bits(void)
{
if (IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) {
/*
* Avoid race of unknown origin for this test, just pretend they
* are atomic.
*/
kcsan_nestable_atomic_begin();
test_var ^= TEST_CHANGE_BITS;
kcsan_nestable_atomic_end();
} else
WRITE_ONCE(test_var, READ_ONCE(test_var) ^ TEST_CHANGE_BITS);
}
static noinline void test_kernel_assert_bits_change(void)
{
ASSERT_EXCLUSIVE_BITS(test_var, TEST_CHANGE_BITS);
}
static noinline void test_kernel_assert_bits_nochange(void)
{
ASSERT_EXCLUSIVE_BITS(test_var, ~TEST_CHANGE_BITS);
}
/*
* Scoped assertions do trigger anywhere in scope. However, the report should
* still only point at the start of the scope.
*/
static noinline void test_enter_scope(void)
{
int x = 0;
/* Unrelated accesses to scoped assert. */
READ_ONCE(test_sink);
kcsan_check_read(&x, sizeof(x));
}
static noinline void test_kernel_assert_writer_scoped(void)
{
ASSERT_EXCLUSIVE_WRITER_SCOPED(test_var);
test_enter_scope();
}
static noinline void test_kernel_assert_access_scoped(void)
{
ASSERT_EXCLUSIVE_ACCESS_SCOPED(test_var);
test_enter_scope();
}
static noinline void test_kernel_rmw_array(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(test_array); ++i)
test_array[i]++;
}
static noinline void test_kernel_write_struct(void)
{
kcsan_check_write(&test_struct, sizeof(test_struct));
kcsan_disable_current();
test_struct.val[3]++; /* induce value change */
kcsan_enable_current();
}
static noinline void test_kernel_write_struct_part(void)
{
test_struct.val[3] = 42;
}
static noinline void test_kernel_read_struct_zero_size(void)
{
kcsan_check_read(&test_struct.val[3], 0);
}
static noinline void test_kernel_jiffies_reader(void)
{
sink_value((long)jiffies);
}
static noinline void test_kernel_seqlock_reader(void)
{
unsigned int seq;
do {
seq = read_seqbegin(&test_seqlock);
sink_value(test_var);
} while (read_seqretry(&test_seqlock, seq));
}
static noinline void test_kernel_seqlock_writer(void)
{
unsigned long flags;
write_seqlock_irqsave(&test_seqlock, flags);
test_var++;
write_sequnlock_irqrestore(&test_seqlock, flags);
}
static noinline void test_kernel_atomic_builtins(void)
{
/*
* Generate concurrent accesses, expecting no reports, ensuring KCSAN
* treats builtin atomics as actually atomic.
*/
__atomic_load_n(&test_var, __ATOMIC_RELAXED);
}
static noinline void test_kernel_xor_1bit(void)
{
/* Do not report data races between the read-writes. */
kcsan_nestable_atomic_begin();
test_var ^= 0x10000;
kcsan_nestable_atomic_end();
}
#define TEST_KERNEL_LOCKED(name, acquire, release) \
static noinline void test_kernel_##name(void) \
{ \
long *flag = &test_struct.val[0]; \
long v = 0; \
if (!(acquire)) \
return; \
while (v++ < 100) { \
test_var++; \
barrier(); \
} \
release; \
test_delay(10); \
}
TEST_KERNEL_LOCKED(with_memorder,
cmpxchg_acquire(flag, 0, 1) == 0,
smp_store_release(flag, 0));
TEST_KERNEL_LOCKED(wrong_memorder,
cmpxchg_relaxed(flag, 0, 1) == 0,
WRITE_ONCE(*flag, 0));
TEST_KERNEL_LOCKED(atomic_builtin_with_memorder,
__atomic_compare_exchange_n(flag, &v, 1, 0, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED),
__atomic_store_n(flag, 0, __ATOMIC_RELEASE));
TEST_KERNEL_LOCKED(atomic_builtin_wrong_memorder,
__atomic_compare_exchange_n(flag, &v, 1, 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED),
__atomic_store_n(flag, 0, __ATOMIC_RELAXED));
/* ===== Test cases ===== */
/*
* Tests that various barriers have the expected effect on internal state. Not
* exhaustive on atomic_t operations. Unlike the selftest, also checks for
* too-strict barrier instrumentation; these can be tolerated, because it does
* not cause false positives, but at least we should be aware of such cases.
*/
static void test_barrier_nothreads(struct kunit *test)
{
#ifdef CONFIG_KCSAN_WEAK_MEMORY
struct kcsan_scoped_access *reorder_access = ¤t->kcsan_ctx.reorder_access;
#else
struct kcsan_scoped_access *reorder_access = NULL;
#endif
arch_spinlock_t arch_spinlock = __ARCH_SPIN_LOCK_UNLOCKED;
atomic_t dummy;
KCSAN_TEST_REQUIRES(test, reorder_access != NULL);
KCSAN_TEST_REQUIRES(test, IS_ENABLED(CONFIG_SMP));
#define __KCSAN_EXPECT_BARRIER(access_type, barrier, order_before, name) \
do { \
reorder_access->type = (access_type) | KCSAN_ACCESS_SCOPED; \
reorder_access->size = sizeof(test_var); \
barrier; \
KUNIT_EXPECT_EQ_MSG(test, reorder_access->size, \
order_before ? 0 : sizeof(test_var), \
"improperly instrumented type=(" #access_type "): " name); \
} while (0)
#define KCSAN_EXPECT_READ_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(0, b, o, #b)
#define KCSAN_EXPECT_WRITE_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(KCSAN_ACCESS_WRITE, b, o, #b)
#define KCSAN_EXPECT_RW_BARRIER(b, o) __KCSAN_EXPECT_BARRIER(KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE, b, o, #b)
/*
* Lockdep initialization can strengthen certain locking operations due
* to calling into instrumented files; "warm up" our locks.
*/
spin_lock(&test_spinlock);
spin_unlock(&test_spinlock);
mutex_lock(&test_mutex);
mutex_unlock(&test_mutex);
/* Force creating a valid entry in reorder_access first. */
test_var = 0;
while (test_var++ < 1000000 && reorder_access->size != sizeof(test_var))
__kcsan_check_read(&test_var, sizeof(test_var));
KUNIT_ASSERT_EQ(test, reorder_access->size, sizeof(test_var));
kcsan_nestable_atomic_begin(); /* No watchpoints in called functions. */
KCSAN_EXPECT_READ_BARRIER(mb(), true);
KCSAN_EXPECT_READ_BARRIER(wmb(), false);
KCSAN_EXPECT_READ_BARRIER(rmb(), true);
KCSAN_EXPECT_READ_BARRIER(smp_mb(), true);
KCSAN_EXPECT_READ_BARRIER(smp_wmb(), false);
KCSAN_EXPECT_READ_BARRIER(smp_rmb(), true);
KCSAN_EXPECT_READ_BARRIER(dma_wmb(), false);
KCSAN_EXPECT_READ_BARRIER(dma_rmb(), true);
KCSAN_EXPECT_READ_BARRIER(smp_mb__before_atomic(), true);
KCSAN_EXPECT_READ_BARRIER(smp_mb__after_atomic(), true);
KCSAN_EXPECT_READ_BARRIER(smp_mb__after_spinlock(), true);
KCSAN_EXPECT_READ_BARRIER(smp_store_mb(test_var, 0), true);
KCSAN_EXPECT_READ_BARRIER(smp_load_acquire(&test_var), false);
KCSAN_EXPECT_READ_BARRIER(smp_store_release(&test_var, 0), true);
KCSAN_EXPECT_READ_BARRIER(xchg(&test_var, 0), true);
KCSAN_EXPECT_READ_BARRIER(xchg_release(&test_var, 0), true);
KCSAN_EXPECT_READ_BARRIER(xchg_relaxed(&test_var, 0), false);
KCSAN_EXPECT_READ_BARRIER(cmpxchg(&test_var, 0, 0), true);
KCSAN_EXPECT_READ_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
KCSAN_EXPECT_READ_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
KCSAN_EXPECT_READ_BARRIER(atomic_read(&dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_read_acquire(&dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_set(&dummy, 0), false);
KCSAN_EXPECT_READ_BARRIER(atomic_set_release(&dummy, 0), true);
KCSAN_EXPECT_READ_BARRIER(atomic_add(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_add_return(1, &dummy), true);
KCSAN_EXPECT_READ_BARRIER(atomic_add_return_acquire(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_add_return_release(1, &dummy), true);
KCSAN_EXPECT_READ_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add(1, &dummy), true);
KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_release(1, &dummy), true);
KCSAN_EXPECT_READ_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
KCSAN_EXPECT_READ_BARRIER(test_and_set_bit(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(test_and_clear_bit(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(test_and_change_bit(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(__clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_READ_BARRIER(arch_spin_lock(&arch_spinlock), false);
KCSAN_EXPECT_READ_BARRIER(arch_spin_unlock(&arch_spinlock), true);
KCSAN_EXPECT_READ_BARRIER(spin_lock(&test_spinlock), false);
KCSAN_EXPECT_READ_BARRIER(spin_unlock(&test_spinlock), true);
KCSAN_EXPECT_READ_BARRIER(mutex_lock(&test_mutex), false);
KCSAN_EXPECT_READ_BARRIER(mutex_unlock(&test_mutex), true);
KCSAN_EXPECT_WRITE_BARRIER(mb(), true);
KCSAN_EXPECT_WRITE_BARRIER(wmb(), true);
KCSAN_EXPECT_WRITE_BARRIER(rmb(), false);
KCSAN_EXPECT_WRITE_BARRIER(smp_mb(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_wmb(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_rmb(), false);
KCSAN_EXPECT_WRITE_BARRIER(dma_wmb(), true);
KCSAN_EXPECT_WRITE_BARRIER(dma_rmb(), false);
KCSAN_EXPECT_WRITE_BARRIER(smp_mb__before_atomic(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_mb__after_atomic(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_mb__after_spinlock(), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_store_mb(test_var, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(smp_load_acquire(&test_var), false);
KCSAN_EXPECT_WRITE_BARRIER(smp_store_release(&test_var, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(xchg(&test_var, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(xchg_release(&test_var, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(xchg_relaxed(&test_var, 0), false);
KCSAN_EXPECT_WRITE_BARRIER(cmpxchg(&test_var, 0, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_read(&dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_read_acquire(&dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_set(&dummy, 0), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_set_release(&dummy, 0), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return(1, &dummy), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_acquire(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_release(1, &dummy), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add(1, &dummy), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_release(1, &dummy), true);
KCSAN_EXPECT_WRITE_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
KCSAN_EXPECT_WRITE_BARRIER(test_and_set_bit(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(test_and_clear_bit(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(test_and_change_bit(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(__clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(arch_spin_lock(&arch_spinlock), false);
KCSAN_EXPECT_WRITE_BARRIER(arch_spin_unlock(&arch_spinlock), true);
KCSAN_EXPECT_WRITE_BARRIER(spin_lock(&test_spinlock), false);
KCSAN_EXPECT_WRITE_BARRIER(spin_unlock(&test_spinlock), true);
KCSAN_EXPECT_WRITE_BARRIER(mutex_lock(&test_mutex), false);
KCSAN_EXPECT_WRITE_BARRIER(mutex_unlock(&test_mutex), true);
KCSAN_EXPECT_RW_BARRIER(mb(), true);
KCSAN_EXPECT_RW_BARRIER(wmb(), true);
KCSAN_EXPECT_RW_BARRIER(rmb(), true);
KCSAN_EXPECT_RW_BARRIER(smp_mb(), true);
KCSAN_EXPECT_RW_BARRIER(smp_wmb(), true);
KCSAN_EXPECT_RW_BARRIER(smp_rmb(), true);
KCSAN_EXPECT_RW_BARRIER(dma_wmb(), true);
KCSAN_EXPECT_RW_BARRIER(dma_rmb(), true);
KCSAN_EXPECT_RW_BARRIER(smp_mb__before_atomic(), true);
KCSAN_EXPECT_RW_BARRIER(smp_mb__after_atomic(), true);
KCSAN_EXPECT_RW_BARRIER(smp_mb__after_spinlock(), true);
KCSAN_EXPECT_RW_BARRIER(smp_store_mb(test_var, 0), true);
KCSAN_EXPECT_RW_BARRIER(smp_load_acquire(&test_var), false);
KCSAN_EXPECT_RW_BARRIER(smp_store_release(&test_var, 0), true);
KCSAN_EXPECT_RW_BARRIER(xchg(&test_var, 0), true);
KCSAN_EXPECT_RW_BARRIER(xchg_release(&test_var, 0), true);
KCSAN_EXPECT_RW_BARRIER(xchg_relaxed(&test_var, 0), false);
KCSAN_EXPECT_RW_BARRIER(cmpxchg(&test_var, 0, 0), true);
KCSAN_EXPECT_RW_BARRIER(cmpxchg_release(&test_var, 0, 0), true);
KCSAN_EXPECT_RW_BARRIER(cmpxchg_relaxed(&test_var, 0, 0), false);
KCSAN_EXPECT_RW_BARRIER(atomic_read(&dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_read_acquire(&dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_set(&dummy, 0), false);
KCSAN_EXPECT_RW_BARRIER(atomic_set_release(&dummy, 0), true);
KCSAN_EXPECT_RW_BARRIER(atomic_add(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_add_return(1, &dummy), true);
KCSAN_EXPECT_RW_BARRIER(atomic_add_return_acquire(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_add_return_release(1, &dummy), true);
KCSAN_EXPECT_RW_BARRIER(atomic_add_return_relaxed(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add(1, &dummy), true);
KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_acquire(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_release(1, &dummy), true);
KCSAN_EXPECT_RW_BARRIER(atomic_fetch_add_relaxed(1, &dummy), false);
KCSAN_EXPECT_RW_BARRIER(test_and_set_bit(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(test_and_clear_bit(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(test_and_change_bit(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(__clear_bit_unlock(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(arch_spin_lock(&arch_spinlock), false);
KCSAN_EXPECT_RW_BARRIER(arch_spin_unlock(&arch_spinlock), true);
KCSAN_EXPECT_RW_BARRIER(spin_lock(&test_spinlock), false);
KCSAN_EXPECT_RW_BARRIER(spin_unlock(&test_spinlock), true);
KCSAN_EXPECT_RW_BARRIER(mutex_lock(&test_mutex), false);
KCSAN_EXPECT_RW_BARRIER(mutex_unlock(&test_mutex), true);
#ifdef clear_bit_unlock_is_negative_byte
KCSAN_EXPECT_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
KCSAN_EXPECT_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
KCSAN_EXPECT_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var), true);
#endif
kcsan_nestable_atomic_end();
}
/* Simple test with normal data race. */
__no_kcsan
static void test_basic(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
},
};
struct expect_report never = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
},
};
bool match_expect = false;
bool match_never = false;
begin_test_checks(test_kernel_write, test_kernel_read);
do {
match_expect |= report_matches(&expect);
match_never = report_matches(&never);
} while (!end_test_checks(match_never));
KUNIT_EXPECT_TRUE(test, match_expect);
KUNIT_EXPECT_FALSE(test, match_never);
}
/*
* Stress KCSAN with lots of concurrent races on different addresses until
* timeout.
*/
__no_kcsan
static void test_concurrent_races(struct kunit *test)
{
struct expect_report expect = {
.access = {
/* NULL will match any address. */
{ test_kernel_rmw_array, NULL, 0, __KCSAN_ACCESS_RW(KCSAN_ACCESS_WRITE) },
{ test_kernel_rmw_array, NULL, 0, __KCSAN_ACCESS_RW(0) },
},
};
struct expect_report never = {
.access = {
{ test_kernel_rmw_array, NULL, 0, 0 },
{ test_kernel_rmw_array, NULL, 0, 0 },
},
};
bool match_expect = false;
bool match_never = false;
begin_test_checks(test_kernel_rmw_array, test_kernel_rmw_array);
do {
match_expect |= report_matches(&expect);
match_never |= report_matches(&never);
} while (!end_test_checks(false));
KUNIT_EXPECT_TRUE(test, match_expect); /* Sanity check matches exist. */
KUNIT_EXPECT_FALSE(test, match_never);
}
/* Test the KCSAN_REPORT_VALUE_CHANGE_ONLY option. */
__no_kcsan
static void test_novalue_change(struct kunit *test)
{
struct expect_report expect_rw = {
.access = {
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
},
};
struct expect_report expect_ww = {
.access = {
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_write_nochange, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
},
};
bool match_expect = false;
test_kernel_write_nochange(); /* Reset value. */
begin_test_checks(test_kernel_write_nochange, test_kernel_read);
do {
match_expect = report_matches(&expect_rw) || report_matches(&expect_ww);
} while (!end_test_checks(match_expect));
if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY))
KUNIT_EXPECT_FALSE(test, match_expect);
else
KUNIT_EXPECT_TRUE(test, match_expect);
}
/*
* Test that the rules where the KCSAN_REPORT_VALUE_CHANGE_ONLY option should
* never apply work.
*/
__no_kcsan
static void test_novalue_change_exception(struct kunit *test)
{
struct expect_report expect_rw = {
.access = {
{ test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
},
};
struct expect_report expect_ww = {
.access = {
{ test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_write_nochange_rcu, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
},
};
bool match_expect = false;
test_kernel_write_nochange_rcu(); /* Reset value. */
begin_test_checks(test_kernel_write_nochange_rcu, test_kernel_read);
do {
match_expect = report_matches(&expect_rw) || report_matches(&expect_ww);
} while (!end_test_checks(match_expect));
KUNIT_EXPECT_TRUE(test, match_expect);
}
/* Test that data races of unknown origin are reported. */
__no_kcsan
static void test_unknown_origin(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ NULL },
},
};
bool match_expect = false;
begin_test_checks(test_kernel_write_uninstrumented, test_kernel_read);
do {
match_expect = report_matches(&expect);
} while (!end_test_checks(match_expect));
if (IS_ENABLED(CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN))
KUNIT_EXPECT_TRUE(test, match_expect);
else
KUNIT_EXPECT_FALSE(test, match_expect);
}
/* Test KCSAN_ASSUME_PLAIN_WRITES_ATOMIC if it is selected. */
__no_kcsan
static void test_write_write_assume_atomic(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
{ test_kernel_write, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE },
},
};
bool match_expect = false;
begin_test_checks(test_kernel_write, test_kernel_write);
do {
sink_value(READ_ONCE(test_var)); /* induce value-change */
match_expect = report_matches(&expect);
} while (!end_test_checks(match_expect));
if (IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC))
KUNIT_EXPECT_FALSE(test, match_expect);
else
KUNIT_EXPECT_TRUE(test, match_expect);
}
/*
* Test that data races with writes larger than word-size are always reported,
* even if KCSAN_ASSUME_PLAIN_WRITES_ATOMIC is selected.
*/
__no_kcsan
static void test_write_write_struct(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
},
};
bool match_expect = false;
begin_test_checks(test_kernel_write_struct, test_kernel_write_struct);
do {
match_expect = report_matches(&expect);
} while (!end_test_checks(match_expect));
KUNIT_EXPECT_TRUE(test, match_expect);
}
/*
* Test that data races where only one write is larger than word-size are always
* reported, even if KCSAN_ASSUME_PLAIN_WRITES_ATOMIC is selected.
*/
__no_kcsan
static void test_write_write_struct_part(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
{ test_kernel_write_struct_part, &test_struct.val[3], sizeof(test_struct.val[3]), KCSAN_ACCESS_WRITE },
},
};
bool match_expect = false;
begin_test_checks(test_kernel_write_struct, test_kernel_write_struct_part);
do {
match_expect = report_matches(&expect);
} while (!end_test_checks(match_expect));
KUNIT_EXPECT_TRUE(test, match_expect);
}
/* Test that races with atomic accesses never result in reports. */
__no_kcsan
static void test_read_atomic_write_atomic(struct kunit *test)
{
bool match_never = false;
begin_test_checks(test_kernel_read_atomic, test_kernel_write_atomic);
do {
match_never = report_available();
} while (!end_test_checks(match_never));
KUNIT_EXPECT_FALSE(test, match_never);
}
/* Test that a race with an atomic and plain access result in reports. */
__no_kcsan
static void test_read_plain_atomic_write(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ test_kernel_write_atomic, &test_var, sizeof(test_var), KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC },
},
};
bool match_expect = false;
KCSAN_TEST_REQUIRES(test, !IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS));
begin_test_checks(test_kernel_read, test_kernel_write_atomic);
do {
match_expect = report_matches(&expect);
} while (!end_test_checks(match_expect));
KUNIT_EXPECT_TRUE(test, match_expect);
}
/* Test that atomic RMWs generate correct report. */
__no_kcsan
static void test_read_plain_atomic_rmw(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_read, &test_var, sizeof(test_var), 0 },
{ test_kernel_atomic_rmw, &test_var, sizeof(test_var),
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC },
},
};
bool match_expect = false;
KCSAN_TEST_REQUIRES(test, !IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS));
begin_test_checks(test_kernel_read, test_kernel_atomic_rmw);
do {
match_expect = report_matches(&expect);
} while (!end_test_checks(match_expect));
KUNIT_EXPECT_TRUE(test, match_expect);
}
/* Zero-sized accesses should never cause data race reports. */
__no_kcsan
static void test_zero_size_access(struct kunit *test)
{
struct expect_report expect = {
.access = {
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
},
};
struct expect_report never = {
.access = {
{ test_kernel_write_struct, &test_struct, sizeof(test_struct), KCSAN_ACCESS_WRITE },
{ test_kernel_read_struct_zero_size, &test_struct.val[3], 0, 0 },
},
};
bool match_expect = false;
bool match_never = false;
begin_test_checks(test_kernel_write_struct, test_kernel_read_struct_zero_size);
do {
match_expect |= report_matches(&expect);
match_never = report_matches(&never);
} while (!end_test_checks(match_never));
KUNIT_EXPECT_TRUE(test, match_expect); /* Sanity check. */
KUNIT_EXPECT_FALSE(test, match_never);
}