libsanitizer/asan/asan_thread.h

   1 //===-- asan_thread.h -------------------------------------------*- C++ -*-===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of AddressSanitizer, an address sanity checker.
   9 //
  10 // ASan-private header for asan_thread.cc.
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef ASAN_THREAD_H
  14 #define ASAN_THREAD_H
  15
  16 #include "asan_allocator.h"
  17 #include "asan_internal.h"
  18 #include "asan_fake_stack.h"
  19 #include "asan_stats.h"
  20 #include "sanitizer_common/sanitizer_common.h"
  21 #include "sanitizer_common/sanitizer_libc.h"
  22 #include "sanitizer_common/sanitizer_thread_registry.h"
  23
  24 namespace __sanitizer {
  25 struct DTLS;
  26 }  // namespace __sanitizer
  27
  28 namespace __asan {
  29
  30 const u32 kInvalidTid = 0xffffff;  // Must fit into 24 bits.
  31 const u32 kMaxNumberOfThreads = (1 << 22);  // 4M
  32
  33 class AsanThread;
  34
  35 // These objects are created for every thread and are never deleted,
  36 // so we can find them by tid even if the thread is long dead.
  37 class AsanThreadContext : public ThreadContextBase {
  38  public:
  39   explicit AsanThreadContext(int tid)
  40       : ThreadContextBase(tid), announced(false),
  41         destructor_iterations(GetPthreadDestructorIterations()), stack_id(0),
  42         thread(nullptr) {}
  43   bool announced;
  44   u8 destructor_iterations;
  45   u32 stack_id;
  46   AsanThread *thread;
  47
  48   void OnCreated(void *arg) override;
  49   void OnFinished() override;
  50
  51   struct CreateThreadContextArgs {
  52     AsanThread *thread;
  53     StackTrace *stack;
  54   };
  55 };
  56
  57 // AsanThreadContext objects are never freed, so we need many of them.
  58 COMPILER_CHECK(sizeof(AsanThreadContext) <= 256);
  59
  60 // AsanThread are stored in TSD and destroyed when the thread dies.
  61 class AsanThread {
  62  public:
  63   static AsanThread *Create(thread_callback_t start_routine, void *arg,
  64                             u32 parent_tid, StackTrace *stack, bool detached);
  65   static void TSDDtor(void *tsd);
  66   void Destroy();
  67
  68   struct InitOptions;
  69   void Init(const InitOptions *options = nullptr);
  70
  71   thread_return_t ThreadStart(tid_t os_id,
  72                               atomic_uintptr_t *signal_thread_is_registered);
  73
  74   uptr stack_top();
  75   uptr stack_bottom();
  76   uptr stack_size();
  77   uptr tls_begin() { return tls_begin_; }
  78   uptr tls_end() { return tls_end_; }
  79   DTLS *dtls() { return dtls_; }
  80   u32 tid() { return context_->tid; }
  81   AsanThreadContext *context() { return context_; }
  82   void set_context(AsanThreadContext *context) { context_ = context; }
  83
  84   struct StackFrameAccess {
  85     uptr offset;
  86     uptr frame_pc;
  87     const char *frame_descr;
  88   };
  89   bool GetStackFrameAccessByAddr(uptr addr, StackFrameAccess *access);
  90
  91   // Returns a pointer to the start of the stack variable's shadow memory.
  92   uptr GetStackVariableShadowStart(uptr addr);
  93
  94   bool AddrIsInStack(uptr addr);
  95
  96   void DeleteFakeStack(int tid) {
  97     if (!fake_stack_) return;
  98     FakeStack *t = fake_stack_;
  99     fake_stack_ = nullptr;
 100     SetTLSFakeStack(nullptr);
 101     t->Destroy(tid);
 102   }
 103
 104   void StartSwitchFiber(FakeStack **fake_stack_save, uptr bottom, uptr size);
 105   void FinishSwitchFiber(FakeStack *fake_stack_save, uptr *bottom_old,
 106                          uptr *size_old);
 107
 108   bool has_fake_stack() {
 109     return !atomic_load(&stack_switching_, memory_order_relaxed) &&
 110            (reinterpret_cast<uptr>(fake_stack_) > 1);
 111   }
 112
 113   FakeStack *fake_stack() {
 114     if (!__asan_option_detect_stack_use_after_return)
 115       return nullptr;
 116     if (atomic_load(&stack_switching_, memory_order_relaxed))
 117       return nullptr;
 118     if (!has_fake_stack())
 119       return AsyncSignalSafeLazyInitFakeStack();
 120     return fake_stack_;
 121   }
 122
 123   // True is this thread is currently unwinding stack (i.e. collecting a stack
 124   // trace). Used to prevent deadlocks on platforms where libc unwinder calls
 125   // malloc internally. See PR17116 for more details.
 126   bool isUnwinding() const { return unwinding_; }
 127   void setUnwinding(bool b) { unwinding_ = b; }
 128
 129   AsanThreadLocalMallocStorage &malloc_storage() { return malloc_storage_; }
 130   AsanStats &stats() { return stats_; }
 131
 132  private:
 133   // NOTE: There is no AsanThread constructor. It is allocated
 134   // via mmap() and *must* be valid in zero-initialized state.
 135
 136   void SetThreadStackAndTls(const InitOptions *options);
 137
 138   void ClearShadowForThreadStackAndTLS();
 139   FakeStack *AsyncSignalSafeLazyInitFakeStack();
 140
 141   struct StackBounds {
 142     uptr bottom;
 143     uptr top;
 144   };
 145   StackBounds GetStackBounds() const;
 146
 147   AsanThreadContext *context_;
 148   thread_callback_t start_routine_;
 149   void *arg_;
 150
 151   uptr stack_top_;
 152   uptr stack_bottom_;
 153   // these variables are used when the thread is about to switch stack
 154   uptr next_stack_top_;
 155   uptr next_stack_bottom_;
 156   // true if switching is in progress
 157   atomic_uint8_t stack_switching_;
 158
 159   uptr tls_begin_;
 160   uptr tls_end_;
 161   DTLS *dtls_;
 162
 163   FakeStack *fake_stack_;
 164   AsanThreadLocalMallocStorage malloc_storage_;
 165   AsanStats stats_;
 166   bool unwinding_;
 167 };
 168
 169 // ScopedUnwinding is a scope for stacktracing member of a context
 170 class ScopedUnwinding {
 171  public:
 172   explicit ScopedUnwinding(AsanThread *t) : thread(t) {
 173     t->setUnwinding(true);
 174   }
 175   ~ScopedUnwinding() { thread->setUnwinding(false); }
 176
 177  private:
 178   AsanThread *thread;
 179 };
 180
 181 // Returns a single instance of registry.
 182 ThreadRegistry &asanThreadRegistry();
 183
 184 // Must be called under ThreadRegistryLock.
 185 AsanThreadContext *GetThreadContextByTidLocked(u32 tid);
 186
 187 // Get the current thread. May return 0.
 188 AsanThread *GetCurrentThread();
 189 void SetCurrentThread(AsanThread *t);
 190 u32 GetCurrentTidOrInvalid();
 191 AsanThread *FindThreadByStackAddress(uptr addr);
 192
 193 // Used to handle fork().
 194 void EnsureMainThreadIDIsCorrect();
 195 } // namespace __asan
 196
 197 #endif // ASAN_THREAD_H