/* * Helper macros to index into adjacent slots, starting from address slot * itself, followed by the right and left slots. * * The purpose is 2-fold: * * 1. if during insertion the address slot is already occupied, check if * any adjacent slots are free; * 2. accesses that straddle a slot boundary due to size that exceeds a * slot's range may check adjacent slots if any watchpoint matches. * * Note that accesses with very large size may still miss a watchpoint; however, * given this should be rare, this is a reasonable trade-off to make, since this * will avoid: * * 1. excessive contention between watchpoint checks and setup; * 2. larger number of simultaneous watchpoints without sacrificing * performance. * * Example: SLOT_IDX values for KCSAN_CHECK_ADJACENT=1, where i is [0, 1, 2]: * * slot=0: [ 1, 2, 0] * slot=9: [10, 11, 9] * slot=63: [64, 65, 63]
*/ #define SLOT_IDX(slot, i) (slot + ((i + KCSAN_CHECK_ADJACENT) % NUM_SLOTS))
/* * SLOT_IDX_FAST is used in the fast-path. Not first checking the address's primary * slot (middle) is fine if we assume that races occur rarely. The set of * indices {SLOT_IDX(slot, i) | i in [0, NUM_SLOTS)} is equivalent to * {SLOT_IDX_FAST(slot, i) | i in [0, NUM_SLOTS)}.
*/ #define SLOT_IDX_FAST(slot, i) (slot + i)
/* * Watchpoints, with each entry encoded as defined in encoding.h: in order to be * able to safely update and access a watchpoint without introducing locking * overhead, we encode each watchpoint as a single atomic long. The initial * zero-initialized state matches INVALID_WATCHPOINT. * * Add NUM_SLOTS-1 entries to account for overflow; this helps avoid having to * use more complicated SLOT_IDX_FAST calculation with modulo in the fast-path.
*/ static atomic_long_t watchpoints[CONFIG_KCSAN_NUM_WATCHPOINTS + NUM_SLOTS-1];
/* * Instructions to skip watching counter, used in should_watch(). We use a * per-CPU counter to avoid excessive contention.
*/ static DEFINE_PER_CPU(long, kcsan_skip);
/* For kcsan_prandom_u32_max(). */ static DEFINE_PER_CPU(u32, kcsan_rand_state);
/* Check slot index logic, ensuring we stay within array bounds. */
BUILD_BUG_ON(SLOT_IDX(0, 0) != KCSAN_CHECK_ADJACENT);
BUILD_BUG_ON(SLOT_IDX(0, KCSAN_CHECK_ADJACENT+1) != 0);
BUILD_BUG_ON(SLOT_IDX(CONFIG_KCSAN_NUM_WATCHPOINTS-1, KCSAN_CHECK_ADJACENT) != ARRAY_SIZE(watchpoints)-1);
BUILD_BUG_ON(SLOT_IDX(CONFIG_KCSAN_NUM_WATCHPOINTS-1, KCSAN_CHECK_ADJACENT+1) != ARRAY_SIZE(watchpoints) - NUM_SLOTS);
for (i = 0; i < NUM_SLOTS; ++i) { long expect_val = INVALID_WATCHPOINT;
/* Try to acquire this slot. */
watchpoint = &watchpoints[SLOT_IDX(slot, i)]; if (atomic_long_try_cmpxchg_relaxed(watchpoint, &expect_val, encoded_watchpoint)) return watchpoint;
}
return NULL;
}
/* * Return true if watchpoint was successfully consumed, false otherwise. * * This may return false if: * * 1. another thread already consumed the watchpoint; * 2. the thread that set up the watchpoint already removed it; * 3. the watchpoint was removed and then re-used.
*/ static __always_inline bool
try_consume_watchpoint(atomic_long_t *watchpoint, long encoded_watchpoint)
{ return atomic_long_try_cmpxchg_relaxed(watchpoint, &encoded_watchpoint, CONSUMED_WATCHPOINT);
}
/* Return true if watchpoint was not touched, false if already consumed. */ staticinlinebool consume_watchpoint(atomic_long_t *watchpoint)
{ return atomic_long_xchg_relaxed(watchpoint, CONSUMED_WATCHPOINT) != CONSUMED_WATCHPOINT;
}
/* Remove the watchpoint -- its slot may be reused after. */ staticinlinevoid remove_watchpoint(atomic_long_t *watchpoint)
{
atomic_long_set(watchpoint, INVALID_WATCHPOINT);
}
static __always_inline struct kcsan_ctx *get_ctx(void)
{ /* * In interrupts, use raw_cpu_ptr to avoid unnecessary checks, that would * also result in calls that generate warnings in uaccess regions.
*/ return in_task() ? ¤t->kcsan_ctx : raw_cpu_ptr(&kcsan_cpu_ctx);
}
/* Check scoped accesses; never inline because this is a slow-path! */ static noinline void kcsan_check_scoped_accesses(void)
{ struct kcsan_ctx *ctx = get_ctx(); struct kcsan_scoped_access *scoped_access;
/* Rules for generic atomic accesses. Called from fast-path. */ static __always_inline bool
is_atomic(struct kcsan_ctx *ctx, constvolatilevoid *ptr, size_t size, int type)
{ if (type & KCSAN_ACCESS_ATOMIC) returntrue;
/* * Unless explicitly declared atomic, never consider an assertion access * as atomic. This allows using them also in atomic regions, such as * seqlocks, without implicitly changing their semantics.
*/ if (type & KCSAN_ACCESS_ASSERT) returnfalse;
if (IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC) &&
(type & KCSAN_ACCESS_WRITE) && size <= sizeof(long) &&
!(type & KCSAN_ACCESS_COMPOUND) && IS_ALIGNED((unsignedlong)ptr, size)) returntrue; /* Assume aligned writes up to word size are atomic. */
if (ctx->atomic_next > 0) { /* * Because we do not have separate contexts for nested * interrupts, in case atomic_next is set, we simply assume that * the outer interrupt set atomic_next. In the worst case, we * will conservatively consider operations as atomic. This is a * reasonable trade-off to make, since this case should be * extremely rare; however, even if extremely rare, it could * lead to false positives otherwise.
*/ if ((hardirq_count() >> HARDIRQ_SHIFT) < 2)
--ctx->atomic_next; /* in task, or outer interrupt */ returntrue;
}
static __always_inline bool
should_watch(struct kcsan_ctx *ctx, constvolatilevoid *ptr, size_t size, int type)
{ /* * Never set up watchpoints when memory operations are atomic. * * Need to check this first, before kcsan_skip check below: (1) atomics * should not count towards skipped instructions, and (2) to actually * decrement kcsan_atomic_next for consecutive instruction stream.
*/ if (is_atomic(ctx, ptr, size, type)) returnfalse;
if (this_cpu_dec_return(kcsan_skip) >= 0) returnfalse;
/* * NOTE: If we get here, kcsan_skip must always be reset in slow path * via reset_kcsan_skip() to avoid underflow.
*/
/* this operation should be watched */ returntrue;
}
/* * Returns a pseudo-random number in interval [0, ep_ro). Simple linear * congruential generator, using constants from "Numerical Recipes".
*/ static u32 kcsan_prandom_u32_max(u32 ep_ro)
{
u32 state = this_cpu_read(kcsan_rand_state);
state = 1664525 * state + 1013904223;
this_cpu_write(kcsan_rand_state, state);
/* * Reads the instrumented memory for value change detection; value change * detection is currently done for accesses up to a size of 8 bytes.
*/ static __always_inline u64 read_instrumented_memory(constvolatilevoid *ptr, size_t size)
{ /* * In the below we don't necessarily need the read of the location to * be atomic, and we don't use READ_ONCE(), since all we need for race * detection is to observe 2 different values. * * Furthermore, on certain architectures (such as arm64), READ_ONCE() * may turn into more complex instructions than a plain load that cannot * do unaligned accesses.
*/ switch (size) { case 1: return *(constvolatile u8 *)ptr; case 2: return *(constvolatile u16 *)ptr; case 4: return *(constvolatile u32 *)ptr; case 8: return *(constvolatile u64 *)ptr; default: return 0; /* Ignore; we do not diff the values. */
}
}
/* * Note: If accesses are repeated while reorder_access is identical, * never matches the new access, because !(type & KCSAN_ACCESS_SCOPED).
*/ return reorder_access->ptr == ptr && reorder_access->size == size &&
reorder_access->type == type && reorder_access->ip == ip;
}
if (!reorder_access || !kcsan_weak_memory) return;
/* * To avoid nested interrupts or scheduler (which share kcsan_ctx) * reading an inconsistent reorder_access, ensure that the below has * exclusive access to reorder_access by disallowing concurrent use.
*/
ctx->disable_scoped++;
barrier();
reorder_access->ptr = ptr;
reorder_access->size = size;
reorder_access->type = type | KCSAN_ACCESS_SCOPED;
reorder_access->ip = ip;
reorder_access->stack_depth = get_kcsan_stack_depth();
barrier();
ctx->disable_scoped--;
}
/* * Pull everything together: check_access() below contains the performance * critical operations; the fast-path (including check_access) functions should * all be inlinable by the instrumentation functions. * * The slow-path (kcsan_found_watchpoint, kcsan_setup_watchpoint) are * non-inlinable -- note that, we prefix these with "kcsan_" to ensure they can * be filtered from the stacktrace, as well as give them unique names for the * UACCESS whitelist of objtool. Each function uses user_access_save/restore(), * since they do not access any user memory, but instrumentation is still * emitted in UACCESS regions.
*/
/* * We know a watchpoint exists. Let's try to keep the race-window * between here and finally consuming the watchpoint below as small as * possible -- avoid unneccessarily complex code until consumed.
*/
if (!kcsan_is_enabled(ctx)) return;
/* * The access_mask check relies on value-change comparison. To avoid * reporting a race where e.g. the writer set up the watchpoint, but the * reader has access_mask!=0, we have to ignore the found watchpoint. * * reorder_access is never created from an access with access_mask set.
*/ if (ctx->access_mask && !find_reorder_access(ctx, ptr, size, type, ip)) return;
/* * If the other thread does not want to ignore the access, and there was * a value change as a result of this thread's operation, we will still * generate a report of unknown origin. * * Use CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN=n to filter.
*/ if (!is_assert && kcsan_ignore_address(ptr)) return;
/* * Consuming the watchpoint must be guarded by kcsan_is_enabled() to * avoid erroneously triggering reports if the context is disabled.
*/
consumed = try_consume_watchpoint(watchpoint, encoded_watchpoint);
/* keep this after try_consume_watchpoint */
flags = user_access_save();
if (consumed) {
kcsan_save_irqtrace(current);
kcsan_report_set_info(ptr, size, type, ip, watchpoint - watchpoints);
kcsan_restore_irqtrace(current);
} else { /* * The other thread may not print any diagnostics, as it has * already removed the watchpoint, or another thread consumed * the watchpoint before this thread.
*/
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_REPORT_RACES]);
}
if (is_assert)
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ASSERT_FAILURES]); else
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_DATA_RACES]);
/* * Always reset kcsan_skip counter in slow-path to avoid underflow; see * should_watch().
*/
reset_kcsan_skip();
if (!kcsan_is_enabled(ctx)) goto out;
/* * Check to-ignore addresses after kcsan_is_enabled(), as we may access * memory that is not yet initialized during early boot.
*/ if (!is_assert && kcsan_ignore_address(ptr)) goto out;
if (!check_encodable((unsignedlong)ptr, size)) {
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_UNENCODABLE_ACCESSES]); goto out;
}
/* * The local CPU cannot observe reordering of its own accesses, and * therefore we need to take care of 2 cases to avoid false positives: * * 1. Races of the reordered access with interrupts. To avoid, if * the current access is reorder_access, disable interrupts. * 2. Avoid races of scoped accesses from nested interrupts (below).
*/
is_reorder_access = find_reorder_access(ctx, ptr, size, type, ip); if (is_reorder_access)
interrupt_watcher = false; /* * Avoid races of scoped accesses from nested interrupts (or scheduler). * Assume setting up a watchpoint for a non-scoped (normal) access that * also conflicts with a current scoped access. In a nested interrupt, * which shares the context, it would check a conflicting scoped access. * To avoid, disable scoped access checking.
*/
ctx->disable_scoped++;
/* * Save and restore the IRQ state trace touched by KCSAN, since KCSAN's * runtime is entered for every memory access, and potentially useful * information is lost if dirtied by KCSAN.
*/
kcsan_save_irqtrace(current); if (!interrupt_watcher)
local_irq_save(irq_flags);
watchpoint = insert_watchpoint((unsignedlong)ptr, size, is_write); if (watchpoint == NULL) { /* * Out of capacity: the size of 'watchpoints', and the frequency * with which should_watch() returns true should be tweaked so * that this case happens very rarely.
*/
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_NO_CAPACITY]); goto out_unlock;
}
/* * Read the current value, to later check and infer a race if the data * was modified via a non-instrumented access, e.g. from a device.
*/
old = is_reorder_access ? 0 : read_instrumented_memory(ptr, size);
/* * Delay this thread, to increase probability of observing a racy * conflicting access.
*/
delay_access(type);
/* * Re-read value, and check if it is as expected; if not, we infer a * racy access.
*/ if (!is_reorder_access) { new = read_instrumented_memory(ptr, size);
} else { /* * Reordered accesses cannot be used for value change detection, * because the memory location may no longer be accessible and * could result in a fault.
*/ new = 0;
access_mask = 0;
}
diff = old ^ new; if (access_mask)
diff &= access_mask;
/* * Check if we observed a value change. * * Also check if the data race should be ignored (the rules depend on * non-zero diff); if it is to be ignored, the below rules for * KCSAN_VALUE_CHANGE_MAYBE apply.
*/ if (diff && !kcsan_ignore_data_race(size, type, old, new, diff))
value_change = KCSAN_VALUE_CHANGE_TRUE;
/* Check if this access raced with another. */ if (!consume_watchpoint(watchpoint)) { /* * Depending on the access type, map a value_change of MAYBE to * TRUE (always report) or FALSE (never report).
*/ if (value_change == KCSAN_VALUE_CHANGE_MAYBE) { if (access_mask != 0) { /* * For access with access_mask, we require a * value-change, as it is likely that races on * ~access_mask bits are expected.
*/
value_change = KCSAN_VALUE_CHANGE_FALSE;
} elseif (size > 8 || is_assert) { /* Always assume a value-change. */
value_change = KCSAN_VALUE_CHANGE_TRUE;
}
}
/* * No need to increment 'data_races' counter, as the racing * thread already did. * * Count 'assert_failures' for each failed ASSERT access, * therefore both this thread and the racing thread may * increment this counter.
*/ if (is_assert && value_change == KCSAN_VALUE_CHANGE_TRUE)
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ASSERT_FAILURES]);
kcsan_report_known_origin(ptr, size, type, ip,
value_change, watchpoint - watchpoints,
old, new, access_mask);
} elseif (value_change == KCSAN_VALUE_CHANGE_TRUE) { /* Inferring a race, since the value should not have changed. */
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN]); if (is_assert)
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ASSERT_FAILURES]);
/* * Remove watchpoint; must be after reporting, since the slot may be * reused after this point.
*/
remove_watchpoint(watchpoint);
atomic_long_dec(&kcsan_counters[KCSAN_COUNTER_USED_WATCHPOINTS]);
out_unlock: if (!interrupt_watcher)
local_irq_restore(irq_flags);
kcsan_restore_irqtrace(current);
ctx->disable_scoped--;
/* * Reordered accesses cannot be used for value change detection, * therefore never consider for reordering if access_mask is set. * ASSERT_EXCLUSIVE are not real accesses, ignore them as well.
*/ if (!access_mask && !is_assert)
set_reorder_access(ctx, ptr, size, type, ip);
out:
user_access_restore(ua_flags);
}
static __always_inline void
check_access(constvolatilevoid *ptr, size_t size, int type, unsignedlong ip)
{
atomic_long_t *watchpoint; long encoded_watchpoint;
/* * Do nothing for 0 sized check; this comparison will be optimized out * for constant sized instrumentation (__tsan_{read,write}N).
*/ if (unlikely(size == 0)) return;
again: /* * Avoid user_access_save in fast-path: find_watchpoint is safe without * user_access_save, as the address that ptr points to is only used to * check if a watchpoint exists; ptr is never dereferenced.
*/
watchpoint = find_watchpoint((unsignedlong)ptr, size,
!(type & KCSAN_ACCESS_WRITE),
&encoded_watchpoint); /* * It is safe to check kcsan_is_enabled() after find_watchpoint in the * slow-path, as long as no state changes that cause a race to be * detected and reported have occurred until kcsan_is_enabled() is * checked.
*/
if (unlikely(watchpoint != NULL))
kcsan_found_watchpoint(ptr, size, type, ip, watchpoint, encoded_watchpoint); else { struct kcsan_ctx *ctx = get_ctx(); /* Call only once in fast-path. */
if (!(type & KCSAN_ACCESS_SCOPED)) { struct kcsan_scoped_access *reorder_access = get_reorder_access(ctx);
if (reorder_access) { /* * reorder_access check: simulates reordering of * the access after subsequent operations.
*/
ptr = reorder_access->ptr;
type = reorder_access->type;
ip = reorder_access->ip; /* * Upon a nested interrupt, this context's * reorder_access can be modified (shared ctx). * We know that upon return, reorder_access is * always invalidated by setting size to 0 via * __tsan_func_exit(). Therefore we must read * and check size after the other fields.
*/
barrier();
size = READ_ONCE(reorder_access->size); if (size) goto again;
}
}
/* * Always checked last, right before returning from runtime; * if reorder_access is valid, checked after it was checked.
*/ if (unlikely(ctx->scoped_accesses.prev))
kcsan_check_scoped_accesses();
}
}
/* === Public interface ===================================================== */
/* * We are in the init task, and no other tasks should be running; * WRITE_ONCE without memory barrier is sufficient.
*/ if (kcsan_early_enable) {
pr_info("enabled early\n");
WRITE_ONCE(kcsan_enabled, true);
}
if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY) ||
IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC) ||
IS_ENABLED(CONFIG_KCSAN_PERMISSIVE) ||
IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) {
pr_warn("non-strict mode configured - use CONFIG_KCSAN_STRICT=y to see all data races\n");
} else {
pr_info("strict mode configured\n");
}
}
void kcsan_enable_current(void)
{ if (get_ctx()->disable_count-- == 0) { /* * Warn if kcsan_enable_current() calls are unbalanced with * kcsan_disable_current() calls, which causes disable_count to * become negative and should not happen.
*/
kcsan_disable_current(); /* restore to 0, KCSAN still enabled */
kcsan_disable_current(); /* disable to generate warning */
WARN(1, "Unbalanced %s()", __func__);
kcsan_enable_current();
}
}
EXPORT_SYMBOL(kcsan_enable_current);
void kcsan_enable_current_nowarn(void)
{ if (get_ctx()->disable_count-- == 0)
kcsan_disable_current();
}
EXPORT_SYMBOL(kcsan_enable_current_nowarn);
void kcsan_nestable_atomic_begin(void)
{ /* * Do *not* check and warn if we are in a flat atomic region: nestable * and flat atomic regions are independent from each other. * See include/linux/kcsan.h: struct kcsan_ctx comments for more * comments.
*/
void kcsan_nestable_atomic_end(void)
{ if (get_ctx()->atomic_nest_count-- == 0) { /* * Warn if kcsan_nestable_atomic_end() calls are unbalanced with * kcsan_nestable_atomic_begin() calls, which causes * atomic_nest_count to become negative and should not happen.
*/
kcsan_nestable_atomic_begin(); /* restore to 0 */
kcsan_disable_current(); /* disable to generate warning */
WARN(1, "Unbalanced %s()", __func__);
kcsan_enable_current();
}
}
EXPORT_SYMBOL(kcsan_nestable_atomic_end);
if (WARN(!ctx->scoped_accesses.prev, "Unbalanced %s()?", __func__)) return;
ctx->disable_count++; /* Disable KCSAN, in case list debugging is on. */
list_del(&sa->list); if (list_empty(&ctx->scoped_accesses)) /* * Ensure we do not enter kcsan_check_scoped_accesses() * slow-path if unnecessary, and avoids requiring list_empty() * in the fast-path (to avoid a READ_ONCE() and potential * uaccess warning).
*/
ctx->scoped_accesses.prev = NULL;
/* * KCSAN uses the same instrumentation that is emitted by supported compilers * for ThreadSanitizer (TSAN). * * When enabled, the compiler emits instrumentation calls (the functions * prefixed with "__tsan" below) for all loads and stores that it generated; * inline asm is not instrumented. * * Note that, not all supported compiler versions distinguish aligned/unaligned * accesses, but e.g. recent versions of Clang do. We simply alias the unaligned * version to the generic version, which can handle both.
*/
/* * Function entry and exit are used to determine the validty of reorder_access. * Reordering of the access ends at the end of the function scope where the * access happened. This is done for two reasons: * * 1. Artificially limits the scope where missing barriers are detected. * This minimizes false positives due to uninstrumented functions that * contain the required barriers but were missed. * * 2. Simplifies generating the stack trace of the access.
*/ void __tsan_func_entry(void *call_pc);
noinline void __tsan_func_entry(void *call_pc)
{ if (!IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY)) return;
if (!IS_ENABLED(CONFIG_KCSAN_WEAK_MEMORY)) return;
reorder_access = get_reorder_access(get_ctx()); if (!reorder_access) goto out;
if (get_kcsan_stack_depth() <= reorder_access->stack_depth) { /* * Access check to catch cases where write without a barrier * (supposed release) was last access in function: because * instrumentation is inserted before the real access, a data * race due to the write giving up a c-s would only be caught if * we do the conflicting access after.
*/
check_access(reorder_access->ptr, reorder_access->size,
reorder_access->type, reorder_access->ip);
reorder_access->size = 0;
reorder_access->stack_depth = INT_MIN;
}
out:
add_kcsan_stack_depth(-1);
}
EXPORT_SYMBOL(__tsan_func_exit);
/* * Instrumentation for atomic builtins (__atomic_*, __sync_*). * * Normal kernel code _should not_ be using them directly, but some * architectures may implement some or all atomics using the compilers' * builtins. * * Note: If an architecture decides to fully implement atomics using the * builtins, because they are implicitly instrumented by KCSAN (and KASAN, * etc.), implementing the ARCH_ATOMIC interface (to get instrumentation via * atomic-instrumented) is no longer necessary. * * TSAN instrumentation replaces atomic accesses with calls to any of the below * functions, whose job is to also execute the operation itself.
*/
/* * Note: CAS operations are always classified as write, even in case they * fail. We cannot perform check_access() after a write, as it might lead to * false positives, in cases such as: * * T0: __atomic_compare_exchange_n(&p->flag, &old, 1, ...) * * T1: if (__atomic_load_n(&p->flag, ...)) { * modify *p; * p->flag = 0; * } * * The only downside is that, if there are 3 threads, with one CAS that * succeeds, another CAS that fails, and an unmarked racing operation, we may * point at the wrong CAS as the source of the race. However, if we assume that * all CAS can succeed in some other execution, the data race is still valid.
*/ #define DEFINE_TSAN_ATOMIC_CMPXCHG(bits, strength, weak) \ int __tsan_atomic##bits##_compare_exchange_##strength(u##bits *ptr, u##bits *exp, \
u##bits val, int mo, int fail_mo); \ int __tsan_atomic##bits##_compare_exchange_##strength(u##bits *ptr, u##bits *exp, \
u##bits val, int mo, int fail_mo) \
{ \
kcsan_atomic_builtin_memorder(mo); \ if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
KCSAN_ACCESS_ATOMIC, _RET_IP_); \
} \ return __atomic_compare_exchange_n(ptr, exp, val, weak, mo, fail_mo); \
} \
EXPORT_SYMBOL(__tsan_atomic##bits##_compare_exchange_##strength)
/* * In instrumented files, we emit instrumentation for barriers by mapping the * kernel barriers to an __atomic_signal_fence(), which is interpreted specially * and otherwise has no relation to a real __atomic_signal_fence(). No known * kernel code uses __atomic_signal_fence(). * * Since fsanitize=thread instrumentation handles __atomic_signal_fence(), which * are turned into calls to __tsan_atomic_signal_fence(), such instrumentation * can be disabled via the __no_kcsan function attribute (vs. an explicit call * which could not). When __no_kcsan is requested, __atomic_signal_fence() * generates no code. * * Note: The result of using __atomic_signal_fence() with KCSAN enabled is * potentially limiting the compiler's ability to reorder operations; however, * if barriers were instrumented with explicit calls (without LTO), the compiler * couldn't optimize much anyway. The result of a hypothetical architecture * using __atomic_signal_fence() in normal code would be KCSAN false negatives.
*/ void __tsan_atomic_signal_fence(int memorder);
noinline void __tsan_atomic_signal_fence(int memorder)
{ switch (memorder) { case __KCSAN_BARRIER_TO_SIGNAL_FENCE_mb:
__kcsan_mb(); break; case __KCSAN_BARRIER_TO_SIGNAL_FENCE_wmb:
__kcsan_wmb(); break; case __KCSAN_BARRIER_TO_SIGNAL_FENCE_rmb:
__kcsan_rmb(); break; case __KCSAN_BARRIER_TO_SIGNAL_FENCE_release:
__kcsan_release(); break; default: break;
}
}
EXPORT_SYMBOL(__tsan_atomic_signal_fence);
#ifdef __HAVE_ARCH_MEMSET void *__tsan_memset(void *s, int c, size_t count);
noinline void *__tsan_memset(void *s, int c, size_t count)
{ /* * Instead of not setting up watchpoints where accessed size is greater * than MAX_ENCODABLE_SIZE, truncate checked size to MAX_ENCODABLE_SIZE.
*/
size_t check_len = min_t(size_t, count, MAX_ENCODABLE_SIZE);
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