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//===-- asan_thread.h -------------------------------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file is a part of AddressSanitizer, an address sanity checker.
// ASan-private header for asan_thread.cpp.
#include "asan_allocator.h"
#include "asan_internal.h"
#include "asan_fake_stack.h"
#include "asan_stats.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_libc.h"
#include "sanitizer_common/sanitizer_thread_registry.h"
namespace __sanitizer {
struct DTLS;
} // namespace __sanitizer
namespace __asan {
class AsanThread;
// These objects are created for every thread and are never deleted,
// so we can find them by tid even if the thread is long dead.
class AsanThreadContext final : public ThreadContextBase {
explicit AsanThreadContext(int tid)
: ThreadContextBase(tid), announced(false),
destructor_iterations(GetPthreadDestructorIterations()), stack_id(0),
thread(nullptr) {}
bool announced;
u8 destructor_iterations;
u32 stack_id;
AsanThread *thread;
void OnCreated(void *arg) override;
void OnFinished() override;
struct CreateThreadContextArgs {
AsanThread *thread;
StackTrace *stack;
// AsanThreadContext objects are never freed, so we need many of them.
COMPILER_CHECK(sizeof(AsanThreadContext) <= 256);
// AsanThread are stored in TSD and destroyed when the thread dies.
class AsanThread {
static AsanThread *Create(thread_callback_t start_routine, void *arg,
u32 parent_tid, StackTrace *stack, bool detached);
static void TSDDtor(void *tsd);
void Destroy();
struct InitOptions;
void Init(const InitOptions *options = nullptr);
thread_return_t ThreadStart(tid_t os_id);
uptr stack_top();
uptr stack_bottom();
uptr stack_size();
uptr tls_begin() { return tls_begin_; }
uptr tls_end() { return tls_end_; }
DTLS *dtls() { return dtls_; }
u32 tid() { return context_->tid; }
AsanThreadContext *context() { return context_; }
void set_context(AsanThreadContext *context) { context_ = context; }
struct StackFrameAccess {
uptr offset;
uptr frame_pc;
const char *frame_descr;
bool GetStackFrameAccessByAddr(uptr addr, StackFrameAccess *access);
// Returns a pointer to the start of the stack variable's shadow memory.
uptr GetStackVariableShadowStart(uptr addr);
bool AddrIsInStack(uptr addr);
void DeleteFakeStack(int tid) {
if (!fake_stack_) return;
FakeStack *t = fake_stack_;
fake_stack_ = nullptr;
void StartSwitchFiber(FakeStack **fake_stack_save, uptr bottom, uptr size);
void FinishSwitchFiber(FakeStack *fake_stack_save, uptr *bottom_old,
uptr *size_old);
FakeStack *get_fake_stack() {
if (atomic_load(&stack_switching_, memory_order_relaxed))
return nullptr;
if (reinterpret_cast<uptr>(fake_stack_) <= 1)
return nullptr;
return fake_stack_;
FakeStack *get_or_create_fake_stack() {
if (atomic_load(&stack_switching_, memory_order_relaxed))
return nullptr;
if (reinterpret_cast<uptr>(fake_stack_) <= 1)
return AsyncSignalSafeLazyInitFakeStack();
return fake_stack_;
// True is this thread is currently unwinding stack (i.e. collecting a stack
// trace). Used to prevent deadlocks on platforms where libc unwinder calls
// malloc internally. See PR17116 for more details.
bool isUnwinding() const { return unwinding_; }
void setUnwinding(bool b) { unwinding_ = b; }
AsanThreadLocalMallocStorage &malloc_storage() { return malloc_storage_; }
AsanStats &stats() { return stats_; }
void *extra_spill_area() { return &extra_spill_area_; }
void *get_arg() { return arg_; }
// NOTE: There is no AsanThread constructor. It is allocated
// via mmap() and *must* be valid in zero-initialized state.
void SetThreadStackAndTls(const InitOptions *options);
void ClearShadowForThreadStackAndTLS();
FakeStack *AsyncSignalSafeLazyInitFakeStack();
struct StackBounds {
uptr bottom;
uptr top;
StackBounds GetStackBounds() const;
AsanThreadContext *context_;
thread_callback_t start_routine_;
void *arg_;
uptr stack_top_;
uptr stack_bottom_;
// these variables are used when the thread is about to switch stack
uptr next_stack_top_;
uptr next_stack_bottom_;
// true if switching is in progress
atomic_uint8_t stack_switching_;
uptr tls_begin_;
uptr tls_end_;
DTLS *dtls_;
FakeStack *fake_stack_;
AsanThreadLocalMallocStorage malloc_storage_;
AsanStats stats_;
bool unwinding_;
uptr extra_spill_area_;
// Returns a single instance of registry.
ThreadRegistry &asanThreadRegistry();
// Must be called under ThreadRegistryLock.
AsanThreadContext *GetThreadContextByTidLocked(u32 tid);
// Get the current thread. May return 0.
AsanThread *GetCurrentThread();
void SetCurrentThread(AsanThread *t);
u32 GetCurrentTidOrInvalid();
AsanThread *FindThreadByStackAddress(uptr addr);
// Used to handle fork().
void EnsureMainThreadIDIsCorrect();
} // namespace __asan
#endif // ASAN_THREAD_H