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[tsan] Fix false positive on dispatch blocks created with the barrier flag #129876

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[tsan] Fix false positive on dispatch blocks created with the barrier flag #129876

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6 changes: 6 additions & 0 deletions compiler-rt/lib/tsan/rtl/tsan_dispatch_defs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,12 @@ extern const dispatch_block_t _dispatch_data_destructor_free;
extern const dispatch_block_t _dispatch_data_destructor_munmap;
} // extern "C"

enum dispatch_block_flags_t : __asan::u64 {
DISPATCH_BLOCK_BARRIER = 0x1
};

#define DISPATCH_BLOCK_PRIVATE_DATA_MAGIC 0xD159B10C // 0xDISPatch_BLOCk

#define DISPATCH_DATA_DESTRUCTOR_DEFAULT nullptr
#define DISPATCH_DATA_DESTRUCTOR_FREE _dispatch_data_destructor_free
#define DISPATCH_DATA_DESTRUCTOR_MUNMAP _dispatch_data_destructor_munmap
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46 changes: 35 additions & 11 deletions compiler-rt/lib/tsan/rtl/tsan_interceptors_libdispatch.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include "tsan_rtl.h"

#include "BlocksRuntime/Block.h"
#include "BlocksRuntime/Block_private.h"
#include "tsan_dispatch_defs.h"

#if SANITIZER_APPLE
Expand Down Expand Up @@ -58,6 +59,20 @@ extern "C" struct dispatch_queue_offsets_s {
const uint16_t dqo_priority_size;
} dispatch_queue_offsets;

static bool IsBarrierBlock(dispatch_block_t block) {
struct BarrierBlock_layout : Block_layout {
// declared in queue_internal.h
struct dispatch_block_private_data_s {
u64 dbpd_magic;
dispatch_block_flags_t dbpd_flags;
} dbpds;
} *closure = (struct BarrierBlock_layout *)block;
if (closure->isa != _NSConcreteMallocBlock) return false;
if (Block_size(block) <= sizeof(BarrierBlock_layout)) return false;
if (closure->dbpds.dbpd_magic != DISPATCH_BLOCK_PRIVATE_DATA_MAGIC) return false;
return !!(closure->dbpds.dbpd_flags & dispatch_block_flags_t::DISPATCH_BLOCK_BARRIER);
}

static bool IsQueueSerial(dispatch_queue_t q) {
CHECK_EQ(dispatch_queue_offsets.dqo_width_size, 2);
uptr width = *(uint16_t *)(((uptr)q) + dispatch_queue_offsets.dqo_width);
Expand Down Expand Up @@ -156,30 +171,39 @@ static void invoke_and_release_block(void *param) {
Block_release(block);
}

#define DISPATCH_INTERCEPT_ASYNC_B(name, barrier) \
#define DISPATCH_INTERCEPT_ASYNC_B(name, barrier, barrier_name) \
TSAN_INTERCEPTOR(void, name, dispatch_queue_t q, dispatch_block_t block) { \
SCOPED_TSAN_INTERCEPTOR(name, q, block); \
SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
dispatch_block_t heap_block = Block_copy(block); \
SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
block_context_t *new_context = \
AllocContext(thr, pc, q, heap_block, &invoke_and_release_block); \
new_context->is_barrier_block = barrier; \
new_context->is_barrier_block = barrier || IsBarrierBlock(block); \
Release(thr, pc, (uptr)new_context); \
SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
REAL(name##_f)(q, new_context, dispatch_callback_wrap); \
if (new_context->is_barrier_block) { \
REAL(barrier_name##_f)(q, new_context, dispatch_callback_wrap); \
} else { \
REAL(name##_f)(q, new_context, dispatch_callback_wrap); \
} \
SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
}

#define DISPATCH_INTERCEPT_SYNC_B(name, barrier) \
#define DISPATCH_INTERCEPT_SYNC_B(name, barrier, barrier_name) \
TSAN_INTERCEPTOR(void, name, dispatch_queue_t q, \
DISPATCH_NOESCAPE dispatch_block_t block) { \
SCOPED_TSAN_INTERCEPTOR(name, q, block); \
bool is_barrier_block = barrier || IsBarrierBlock(block); \
block_context_t new_context = { \
q, block, &invoke_block, false, true, barrier, 0}; \
q, block, &invoke_block, false, true, is_barrier_block, 0}; \
Release(thr, pc, (uptr)&new_context); \
SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
REAL(name##_f)(q, &new_context, dispatch_callback_wrap); \
if (new_context.is_barrier_block) { \
REAL(barrier_name##_f)(q, &new_context, dispatch_callback_wrap); \
} else { \
REAL(name##_f)(q, &new_context, dispatch_callback_wrap); \
} \
SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
Acquire(thr, pc, (uptr)&new_context); \
}
Expand Down Expand Up @@ -212,16 +236,16 @@ static void invoke_and_release_block(void *param) {

#define DISPATCH_INTERCEPT(name, barrier) \
DISPATCH_INTERCEPT_ASYNC_F(name##_async_f, barrier) \
DISPATCH_INTERCEPT_ASYNC_B(name##_async, barrier) \
DISPATCH_INTERCEPT_ASYNC_B(name##_async, barrier, dispatch_barrier_async) \
DISPATCH_INTERCEPT_SYNC_F(name##_sync_f, barrier) \
DISPATCH_INTERCEPT_SYNC_B(name##_sync, barrier)
DISPATCH_INTERCEPT_SYNC_B(name##_sync, barrier, dispatch_barrier_sync)

// We wrap dispatch_async, dispatch_sync and friends where we allocate a new
// context, which is used to synchronize (we release the context before
// submitting, and the callback acquires it before executing the original
// callback).
DISPATCH_INTERCEPT(dispatch, false)
DISPATCH_INTERCEPT(dispatch_barrier, true)
DISPATCH_INTERCEPT(dispatch, false)

// dispatch_async_and_wait() and friends were introduced in macOS 10.14.
// Linking of these interceptors fails when using an older SDK.
Expand All @@ -241,9 +265,9 @@ SANITIZER_WEAK_IMPORT void dispatch_barrier_async_and_wait_f(
dispatch_queue_t queue, void *context, dispatch_function_t work);

DISPATCH_INTERCEPT_SYNC_F(dispatch_async_and_wait_f, false)
DISPATCH_INTERCEPT_SYNC_B(dispatch_async_and_wait, false)
DISPATCH_INTERCEPT_SYNC_B(dispatch_async_and_wait, false, dispatch_barrier_async_and_wait)
DISPATCH_INTERCEPT_SYNC_F(dispatch_barrier_async_and_wait_f, true)
DISPATCH_INTERCEPT_SYNC_B(dispatch_barrier_async_and_wait, true)
DISPATCH_INTERCEPT_SYNC_B(dispatch_barrier_async_and_wait, true, dispatch_barrier_async_and_wait)
#endif


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