1 //===-- asan_thread.h -------------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 //
12 // ASan-private header for asan_thread.cc.
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef ASAN_THREAD_H
16 #define ASAN_THREAD_H
17 
18 #include "asan_allocator.h"
19 #include "asan_internal.h"
20 #include "asan_fake_stack.h"
21 #include "asan_stats.h"
22 #include "sanitizer_common/sanitizer_common.h"
23 #include "sanitizer_common/sanitizer_libc.h"
24 #include "sanitizer_common/sanitizer_thread_registry.h"
25 
26 namespace __asan {
27 
28 const u32 kInvalidTid = 0xffffff;  // Must fit into 24 bits.
29 const u32 kMaxNumberOfThreads = (1 << 22);  // 4M
30 
31 class AsanThread;
32 
33 // These objects are created for every thread and are never deleted,
34 // so we can find them by tid even if the thread is long dead.
35 class AsanThreadContext : public ThreadContextBase {
36  public:
AsanThreadContext(int tid)37   explicit AsanThreadContext(int tid)
38       : ThreadContextBase(tid), announced(false),
39         destructor_iterations(GetPthreadDestructorIterations()), stack_id(0),
40         thread(nullptr) {}
41   bool announced;
42   u8 destructor_iterations;
43   u32 stack_id;
44   AsanThread *thread;
45 
46   void OnCreated(void *arg) override;
47   void OnFinished() override;
48 };
49 
50 // AsanThreadContext objects are never freed, so we need many of them.
51 COMPILER_CHECK(sizeof(AsanThreadContext) <= 256);
52 
53 // AsanThread are stored in TSD and destroyed when the thread dies.
54 class AsanThread {
55  public:
56   static AsanThread *Create(thread_callback_t start_routine, void *arg,
57                             u32 parent_tid, StackTrace *stack, bool detached);
58   static void TSDDtor(void *tsd);
59   void Destroy();
60 
61   void Init();  // Should be called from the thread itself.
62   thread_return_t ThreadStart(uptr os_id,
63                               atomic_uintptr_t *signal_thread_is_registered);
64 
stack_top()65   uptr stack_top() { return stack_top_; }
stack_bottom()66   uptr stack_bottom() { return stack_bottom_; }
stack_size()67   uptr stack_size() { return stack_size_; }
tls_begin()68   uptr tls_begin() { return tls_begin_; }
tls_end()69   uptr tls_end() { return tls_end_; }
tid()70   u32 tid() { return context_->tid; }
context()71   AsanThreadContext *context() { return context_; }
set_context(AsanThreadContext * context)72   void set_context(AsanThreadContext *context) { context_ = context; }
73 
74   struct StackFrameAccess {
75     uptr offset;
76     uptr frame_pc;
77     const char *frame_descr;
78   };
79   bool GetStackFrameAccessByAddr(uptr addr, StackFrameAccess *access);
80 
AddrIsInStack(uptr addr)81   bool AddrIsInStack(uptr addr) {
82     return addr >= stack_bottom_ && addr < stack_top_;
83   }
84 
DeleteFakeStack(int tid)85   void DeleteFakeStack(int tid) {
86     if (!fake_stack_) return;
87     FakeStack *t = fake_stack_;
88     fake_stack_ = nullptr;
89     SetTLSFakeStack(nullptr);
90     t->Destroy(tid);
91   }
92 
has_fake_stack()93   bool has_fake_stack() {
94     return (reinterpret_cast<uptr>(fake_stack_) > 1);
95   }
96 
fake_stack()97   FakeStack *fake_stack() {
98     if (!__asan_option_detect_stack_use_after_return)
99       return nullptr;
100     if (!has_fake_stack())
101       return AsyncSignalSafeLazyInitFakeStack();
102     return fake_stack_;
103   }
104 
105   // True is this thread is currently unwinding stack (i.e. collecting a stack
106   // trace). Used to prevent deadlocks on platforms where libc unwinder calls
107   // malloc internally. See PR17116 for more details.
isUnwinding()108   bool isUnwinding() const { return unwinding_; }
setUnwinding(bool b)109   void setUnwinding(bool b) { unwinding_ = b; }
110 
111   // True if we are in a deadly signal handler.
isInDeadlySignal()112   bool isInDeadlySignal() const { return in_deadly_signal_; }
setInDeadlySignal(bool b)113   void setInDeadlySignal(bool b) { in_deadly_signal_ = b; }
114 
malloc_storage()115   AsanThreadLocalMallocStorage &malloc_storage() { return malloc_storage_; }
stats()116   AsanStats &stats() { return stats_; }
117 
118  private:
119   // NOTE: There is no AsanThread constructor. It is allocated
120   // via mmap() and *must* be valid in zero-initialized state.
121   void SetThreadStackAndTls();
122   void ClearShadowForThreadStackAndTLS();
123   FakeStack *AsyncSignalSafeLazyInitFakeStack();
124 
125   AsanThreadContext *context_;
126   thread_callback_t start_routine_;
127   void *arg_;
128   uptr stack_top_;
129   uptr stack_bottom_;
130   // stack_size_ == stack_top_ - stack_bottom_;
131   // It needs to be set in a async-signal-safe manner.
132   uptr stack_size_;
133   uptr tls_begin_;
134   uptr tls_end_;
135 
136   FakeStack *fake_stack_;
137   AsanThreadLocalMallocStorage malloc_storage_;
138   AsanStats stats_;
139   bool unwinding_;
140   bool in_deadly_signal_;
141 };
142 
143 // ScopedUnwinding is a scope for stacktracing member of a context
144 class ScopedUnwinding {
145  public:
ScopedUnwinding(AsanThread * t)146   explicit ScopedUnwinding(AsanThread *t) : thread(t) {
147     t->setUnwinding(true);
148   }
~ScopedUnwinding()149   ~ScopedUnwinding() { thread->setUnwinding(false); }
150 
151  private:
152   AsanThread *thread;
153 };
154 
155 // ScopedDeadlySignal is a scope for handling deadly signals.
156 class ScopedDeadlySignal {
157  public:
ScopedDeadlySignal(AsanThread * t)158   explicit ScopedDeadlySignal(AsanThread *t) : thread(t) {
159     if (thread) thread->setInDeadlySignal(true);
160   }
~ScopedDeadlySignal()161   ~ScopedDeadlySignal() {
162     if (thread) thread->setInDeadlySignal(false);
163   }
164 
165  private:
166   AsanThread *thread;
167 };
168 
169 // Returns a single instance of registry.
170 ThreadRegistry &asanThreadRegistry();
171 
172 // Must be called under ThreadRegistryLock.
173 AsanThreadContext *GetThreadContextByTidLocked(u32 tid);
174 
175 // Get the current thread. May return 0.
176 AsanThread *GetCurrentThread();
177 void SetCurrentThread(AsanThread *t);
178 u32 GetCurrentTidOrInvalid();
179 AsanThread *FindThreadByStackAddress(uptr addr);
180 
181 // Used to handle fork().
182 void EnsureMainThreadIDIsCorrect();
183 } // namespace __asan
184 
185 #endif // ASAN_THREAD_H
186