asan_thread.h revision 353358 
1//===-- asan_thread.h -------------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file is a part of AddressSanitizer, an address sanity checker.
10//
11// ASan-private header for asan_thread.cc.
12//===----------------------------------------------------------------------===//
13
14#ifndef ASAN_THREAD_H
15#define ASAN_THREAD_H
16
17#include "asan_allocator.h"
18#include "asan_internal.h"
19#include "asan_fake_stack.h"
20#include "asan_stats.h"
21#include "sanitizer_common/sanitizer_common.h"
22#include "sanitizer_common/sanitizer_libc.h"
23#include "sanitizer_common/sanitizer_thread_registry.h"
24
25namespace __sanitizer {
26struct DTLS;
27}  // namespace __sanitizer
28
29namespace __asan {
30
31const u32 kInvalidTid = 0xffffff;  // Must fit into 24 bits.
32const u32 kMaxNumberOfThreads = (1 << 22);  // 4M
33
34class AsanThread;
35
36// These objects are created for every thread and are never deleted,
37// so we can find them by tid even if the thread is long dead.
38class AsanThreadContext : public ThreadContextBase {
39 public:
40  explicit AsanThreadContext(int tid)
41      : ThreadContextBase(tid), announced(false),
42        destructor_iterations(GetPthreadDestructorIterations()), stack_id(0),
43        thread(nullptr) {}
44  bool announced;
45  u8 destructor_iterations;
46  u32 stack_id;
47  AsanThread *thread;
48
49  void OnCreated(void *arg) override;
50  void OnFinished() override;
51
52  struct CreateThreadContextArgs {
53    AsanThread *thread;
54    StackTrace *stack;
55  };
56};
57
58// AsanThreadContext objects are never freed, so we need many of them.
59COMPILER_CHECK(sizeof(AsanThreadContext) <= 256);
60
61// AsanThread are stored in TSD and destroyed when the thread dies.
62class AsanThread {
63 public:
64  static AsanThread *Create(thread_callback_t start_routine, void *arg,
65                            u32 parent_tid, StackTrace *stack, bool detached);
66  static void TSDDtor(void *tsd);
67  void Destroy();
68
69  struct InitOptions;
70  void Init(const InitOptions *options = nullptr);
71
72  thread_return_t ThreadStart(tid_t os_id,
73                              atomic_uintptr_t *signal_thread_is_registered);
74
75  uptr stack_top();
76  uptr stack_bottom();
77  uptr stack_size();
78  uptr tls_begin() { return tls_begin_; }
79  uptr tls_end() { return tls_end_; }
80  DTLS *dtls() { return dtls_; }
81  u32 tid() { return context_->tid; }
82  AsanThreadContext *context() { return context_; }
83  void set_context(AsanThreadContext *context) { context_ = context; }
84
85  struct StackFrameAccess {
86    uptr offset;
87    uptr frame_pc;
88    const char *frame_descr;
89  };
90  bool GetStackFrameAccessByAddr(uptr addr, StackFrameAccess *access);
91
92  // Returns a pointer to the start of the stack variable's shadow memory.
93  uptr GetStackVariableShadowStart(uptr addr);
94
95  bool AddrIsInStack(uptr addr);
96
97  void DeleteFakeStack(int tid) {
98    if (!fake_stack_) return;
99    FakeStack *t = fake_stack_;
100    fake_stack_ = nullptr;
101    SetTLSFakeStack(nullptr);
102    t->Destroy(tid);
103  }
104
105  void StartSwitchFiber(FakeStack **fake_stack_save, uptr bottom, uptr size);
106  void FinishSwitchFiber(FakeStack *fake_stack_save, uptr *bottom_old,
107                         uptr *size_old);
108
109  bool has_fake_stack() {
110    return !atomic_load(&stack_switching_, memory_order_relaxed) &&
111           (reinterpret_cast<uptr>(fake_stack_) > 1);
112  }
113
114  FakeStack *fake_stack() {
115    if (!__asan_option_detect_stack_use_after_return)
116      return nullptr;
117    if (atomic_load(&stack_switching_, memory_order_relaxed))
118      return nullptr;
119    if (!has_fake_stack())
120      return AsyncSignalSafeLazyInitFakeStack();
121    return fake_stack_;
122  }
123
124  // True is this thread is currently unwinding stack (i.e. collecting a stack
125  // trace). Used to prevent deadlocks on platforms where libc unwinder calls
126  // malloc internally. See PR17116 for more details.
127  bool isUnwinding() const { return unwinding_; }
128  void setUnwinding(bool b) { unwinding_ = b; }
129
130  AsanThreadLocalMallocStorage &malloc_storage() { return malloc_storage_; }
131  AsanStats &stats() { return stats_; }
132
133  void *extra_spill_area() { return &extra_spill_area_; }
134
135 private:
136  // NOTE: There is no AsanThread constructor. It is allocated
137  // via mmap() and *must* be valid in zero-initialized state.
138
139  void SetThreadStackAndTls(const InitOptions *options);
140
141  void ClearShadowForThreadStackAndTLS();
142  FakeStack *AsyncSignalSafeLazyInitFakeStack();
143
144  struct StackBounds {
145    uptr bottom;
146    uptr top;
147  };
148  StackBounds GetStackBounds() const;
149
150  AsanThreadContext *context_;
151  thread_callback_t start_routine_;
152  void *arg_;
153
154  uptr stack_top_;
155  uptr stack_bottom_;
156  // these variables are used when the thread is about to switch stack
157  uptr next_stack_top_;
158  uptr next_stack_bottom_;
159  // true if switching is in progress
160  atomic_uint8_t stack_switching_;
161
162  uptr tls_begin_;
163  uptr tls_end_;
164  DTLS *dtls_;
165
166  FakeStack *fake_stack_;
167  AsanThreadLocalMallocStorage malloc_storage_;
168  AsanStats stats_;
169  bool unwinding_;
170  uptr extra_spill_area_;
171};
172
173// Returns a single instance of registry.
174ThreadRegistry &asanThreadRegistry();
175
176// Must be called under ThreadRegistryLock.
177AsanThreadContext *GetThreadContextByTidLocked(u32 tid);
178
179// Get the current thread. May return 0.
180AsanThread *GetCurrentThread();
181void SetCurrentThread(AsanThread *t);
182u32 GetCurrentTidOrInvalid();
183AsanThread *FindThreadByStackAddress(uptr addr);
184
185// Used to handle fork().
186void EnsureMainThreadIDIsCorrect();
187} // namespace __asan
188
189#endif // ASAN_THREAD_H
190