libsanitizer/asan/asan_thread.cc

   1 //===-- asan_thread.cc ----------------------------------------------------===//
   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 // Thread-related code.
  11 //===----------------------------------------------------------------------===//
  12 #include "asan_allocator.h"
  13 #include "asan_interceptors.h"
  14 #include "asan_poisoning.h"
  15 #include "asan_stack.h"
  16 #include "asan_thread.h"
  17 #include "asan_mapping.h"
  18 #include "sanitizer_common/sanitizer_common.h"
  19 #include "sanitizer_common/sanitizer_placement_new.h"
  20 #include "sanitizer_common/sanitizer_stackdepot.h"
  21 #include "lsan/lsan_common.h"
  22
  23 namespace __asan {
  24
  25 // AsanThreadContext implementation.
  26
  27 void AsanThreadContext::OnCreated(void *arg) {
  28   CreateThreadContextArgs *args = static_cast<CreateThreadContextArgs*>(arg);
  29   if (args->stack)
  30     stack_id = StackDepotPut(args->stack->trace, args->stack->size);
  31   thread = args->thread;
  32   thread->set_context(this);
  33 }
  34
  35 void AsanThreadContext::OnFinished() {
  36   // Drop the link to the AsanThread object.
  37   thread = 0;
  38 }
  39
  40 // MIPS requires aligned address
  41 static ALIGNED(16) char thread_registry_placeholder[sizeof(ThreadRegistry)];
  42 static ThreadRegistry *asan_thread_registry;
  43
  44 static BlockingMutex mu_for_thread_context(LINKER_INITIALIZED);
  45 static LowLevelAllocator allocator_for_thread_context;
  46
  47 static ThreadContextBase *GetAsanThreadContext(u32 tid) {
  48   BlockingMutexLock lock(&mu_for_thread_context);
  49   return new(allocator_for_thread_context) AsanThreadContext(tid);
  50 }
  51
  52 ThreadRegistry &asanThreadRegistry() {
  53   static bool initialized;
  54   // Don't worry about thread_safety - this should be called when there is
  55   // a single thread.
  56   if (!initialized) {
  57     // Never reuse ASan threads: we store pointer to AsanThreadContext
  58     // in TSD and can't reliably tell when no more TSD destructors will
  59     // be called. It would be wrong to reuse AsanThreadContext for another
  60     // thread before all TSD destructors will be called for it.
  61     asan_thread_registry = new(thread_registry_placeholder) ThreadRegistry(
  62         GetAsanThreadContext, kMaxNumberOfThreads, kMaxNumberOfThreads);
  63     initialized = true;
  64   }
  65   return *asan_thread_registry;
  66 }
  67
  68 AsanThreadContext *GetThreadContextByTidLocked(u32 tid) {
  69   return static_cast<AsanThreadContext *>(
  70       asanThreadRegistry().GetThreadLocked(tid));
  71 }
  72
  73 // AsanThread implementation.
  74
  75 AsanThread *AsanThread::Create(thread_callback_t start_routine,
  76                                void *arg) {
  77   uptr PageSize = GetPageSizeCached();
  78   uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
  79   AsanThread *thread = (AsanThread*)MmapOrDie(size, __FUNCTION__);
  80   thread->start_routine_ = start_routine;
  81   thread->arg_ = arg;
  82
  83   return thread;
  84 }
  85
  86 void AsanThread::TSDDtor(void *tsd) {
  87   AsanThreadContext *context = (AsanThreadContext*)tsd;
  88   if (common_flags()->verbosity >= 1)
  89     Report("T%d TSDDtor\n", context->tid);
  90   if (context->thread)
  91     context->thread->Destroy();
  92 }
  93
  94 void AsanThread::Destroy() {
  95   if (common_flags()->verbosity >= 1) {
  96     Report("T%d exited\n", tid());
  97   }
  98
  99   malloc_storage().CommitBack();
 100   if (flags()->use_sigaltstack) UnsetAlternateSignalStack();
 101   asanThreadRegistry().FinishThread(tid());
 102   FlushToDeadThreadStats(&stats_);
 103   // We also clear the shadow on thread destruction because
 104   // some code may still be executing in later TSD destructors
 105   // and we don't want it to have any poisoned stack.
 106   ClearShadowForThreadStackAndTLS();
 107   DeleteFakeStack();
 108   uptr size = RoundUpTo(sizeof(AsanThread), GetPageSizeCached());
 109   UnmapOrDie(this, size);
 110 }
 111
 112 // We want to create the FakeStack lazyly on the first use, but not eralier
 113 // than the stack size is known and the procedure has to be async-signal safe.
 114 FakeStack *AsanThread::AsyncSignalSafeLazyInitFakeStack() {
 115   uptr stack_size = this->stack_size();
 116   if (stack_size == 0)  // stack_size is not yet available, don't use FakeStack.
 117     return 0;
 118   uptr old_val = 0;
 119   // fake_stack_ has 3 states:
 120   // 0   -- not initialized
 121   // 1   -- being initialized
 122   // ptr -- initialized
 123   // This CAS checks if the state was 0 and if so changes it to state 1,
 124   // if that was successfull, it initilizes the pointer.
 125   if (atomic_compare_exchange_strong(
 126       reinterpret_cast<atomic_uintptr_t *>(&fake_stack_), &old_val, 1UL,
 127       memory_order_relaxed)) {
 128     uptr stack_size_log = Log2(RoundUpToPowerOfTwo(stack_size));
 129     if (flags()->uar_stack_size_log)
 130       stack_size_log = static_cast<uptr>(flags()->uar_stack_size_log);
 131     fake_stack_ = FakeStack::Create(stack_size_log);
 132     SetTLSFakeStack(fake_stack_);
 133     return fake_stack_;
 134   }
 135   return 0;
 136 }
 137
 138 void AsanThread::Init() {
 139   SetThreadStackAndTls();
 140   CHECK(AddrIsInMem(stack_bottom_));
 141   CHECK(AddrIsInMem(stack_top_ - 1));
 142   ClearShadowForThreadStackAndTLS();
 143   if (common_flags()->verbosity >= 1) {
 144     int local = 0;
 145     Report("T%d: stack [%p,%p) size 0x%zx; local=%p\n",
 146            tid(), (void*)stack_bottom_, (void*)stack_top_,
 147            stack_top_ - stack_bottom_, &local);
 148   }
 149   fake_stack_ = 0;  // Will be initialized lazily if needed.
 150   AsanPlatformThreadInit();
 151 }
 152
 153 thread_return_t AsanThread::ThreadStart(uptr os_id) {
 154   Init();
 155   asanThreadRegistry().StartThread(tid(), os_id, 0);
 156   if (flags()->use_sigaltstack) SetAlternateSignalStack();
 157
 158   if (!start_routine_) {
 159     // start_routine_ == 0 if we're on the main thread or on one of the
 160     // OS X libdispatch worker threads. But nobody is supposed to call
 161     // ThreadStart() for the worker threads.
 162     CHECK_EQ(tid(), 0);
 163     return 0;
 164   }
 165
 166   thread_return_t res = start_routine_(arg_);
 167
 168   // On POSIX systems we defer this to the TSD destructor. LSan will consider
 169   // the thread's memory as non-live from the moment we call Destroy(), even
 170   // though that memory might contain pointers to heap objects which will be
 171   // cleaned up by a user-defined TSD destructor. Thus, calling Destroy() before
 172   // the TSD destructors have run might cause false positives in LSan.
 173   if (!SANITIZER_POSIX)
 174     this->Destroy();
 175
 176   return res;
 177 }
 178
 179 void AsanThread::SetThreadStackAndTls() {
 180   uptr tls_size = 0;
 181   GetThreadStackAndTls(tid() == 0, &stack_bottom_, &stack_size_, &tls_begin_,
 182                        &tls_size);
 183   stack_top_ = stack_bottom_ + stack_size_;
 184   tls_end_ = tls_begin_ + tls_size;
 185
 186   int local;
 187   CHECK(AddrIsInStack((uptr)&local));
 188 }
 189
 190 void AsanThread::ClearShadowForThreadStackAndTLS() {
 191   PoisonShadow(stack_bottom_, stack_top_ - stack_bottom_, 0);
 192   if (tls_begin_ != tls_end_)
 193     PoisonShadow(tls_begin_, tls_end_ - tls_begin_, 0);
 194 }
 195
 196 const char *AsanThread::GetFrameNameByAddr(uptr addr, uptr *offset,
 197                                            uptr *frame_pc) {
 198   uptr bottom = 0;
 199   if (AddrIsInStack(addr)) {
 200     bottom = stack_bottom();
 201   } else if (has_fake_stack()) {
 202     bottom = fake_stack()->AddrIsInFakeStack(addr);
 203     CHECK(bottom);
 204     *offset = addr - bottom;
 205     *frame_pc = ((uptr*)bottom)[2];
 206     return  (const char *)((uptr*)bottom)[1];
 207   }
 208   uptr aligned_addr = addr & ~(SANITIZER_WORDSIZE/8 - 1);  // align addr.
 209   u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
 210   u8 *shadow_bottom = (u8*)MemToShadow(bottom);
 211
 212   while (shadow_ptr >= shadow_bottom &&
 213          *shadow_ptr != kAsanStackLeftRedzoneMagic) {
 214     shadow_ptr--;
 215   }
 216
 217   while (shadow_ptr >= shadow_bottom &&
 218          *shadow_ptr == kAsanStackLeftRedzoneMagic) {
 219     shadow_ptr--;
 220   }
 221
 222   if (shadow_ptr < shadow_bottom) {
 223     *offset = 0;
 224     return "UNKNOWN";
 225   }
 226
 227   uptr* ptr = (uptr*)SHADOW_TO_MEM((uptr)(shadow_ptr + 1));
 228   CHECK(ptr[0] == kCurrentStackFrameMagic);
 229   *offset = addr - (uptr)ptr;
 230   *frame_pc = ptr[2];
 231   return (const char*)ptr[1];
 232 }
 233
 234 static bool ThreadStackContainsAddress(ThreadContextBase *tctx_base,
 235                                        void *addr) {
 236   AsanThreadContext *tctx = static_cast<AsanThreadContext*>(tctx_base);
 237   AsanThread *t = tctx->thread;
 238   if (!t) return false;
 239   if (t->AddrIsInStack((uptr)addr)) return true;
 240   if (t->has_fake_stack() && t->fake_stack()->AddrIsInFakeStack((uptr)addr))
 241     return true;
 242   return false;
 243 }
 244
 245 AsanThread *GetCurrentThread() {
 246   AsanThreadContext *context =
 247       reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
 248   if (!context) {
 249     if (SANITIZER_ANDROID) {
 250       // On Android, libc constructor is called _after_ asan_init, and cleans up
 251       // TSD. Try to figure out if this is still the main thread by the stack
 252       // address. We are not entirely sure that we have correct main thread
 253       // limits, so only do this magic on Android, and only if the found thread
 254       // is the main thread.
 255       AsanThreadContext *tctx = GetThreadContextByTidLocked(0);
 256       if (ThreadStackContainsAddress(tctx, &context)) {
 257         SetCurrentThread(tctx->thread);
 258         return tctx->thread;
 259       }
 260     }
 261     return 0;
 262   }
 263   return context->thread;
 264 }
 265
 266 void SetCurrentThread(AsanThread *t) {
 267   CHECK(t->context());
 268   if (common_flags()->verbosity >= 2) {
 269     Report("SetCurrentThread: %p for thread %p\n",
 270            t->context(), (void*)GetThreadSelf());
 271   }
 272   // Make sure we do not reset the current AsanThread.
 273   CHECK_EQ(0, AsanTSDGet());
 274   AsanTSDSet(t->context());
 275   CHECK_EQ(t->context(), AsanTSDGet());
 276 }
 277
 278 u32 GetCurrentTidOrInvalid() {
 279   AsanThread *t = GetCurrentThread();
 280   return t ? t->tid() : kInvalidTid;
 281 }
 282
 283 AsanThread *FindThreadByStackAddress(uptr addr) {
 284   asanThreadRegistry().CheckLocked();
 285   AsanThreadContext *tctx = static_cast<AsanThreadContext *>(
 286       asanThreadRegistry().FindThreadContextLocked(ThreadStackContainsAddress,
 287                                                    (void *)addr));
 288   return tctx ? tctx->thread : 0;
 289 }
 290
 291 void EnsureMainThreadIDIsCorrect() {
 292   AsanThreadContext *context =
 293       reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
 294   if (context && (context->tid == 0))
 295     context->os_id = GetTid();
 296 }
 297
 298 __asan::AsanThread *GetAsanThreadByOsIDLocked(uptr os_id) {
 299   __asan::AsanThreadContext *context = static_cast<__asan::AsanThreadContext *>(
 300       __asan::asanThreadRegistry().FindThreadContextByOsIDLocked(os_id));
 301   if (!context) return 0;
 302   return context->thread;
 303 }
 304 }  // namespace __asan
 305
 306 // --- Implementation of LSan-specific functions --- {{{1
 307 namespace __lsan {
 308 bool GetThreadRangesLocked(uptr os_id, uptr *stack_begin, uptr *stack_end,
 309                            uptr *tls_begin, uptr *tls_end,
 310                            uptr *cache_begin, uptr *cache_end) {
 311   __asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id);
 312   if (!t) return false;
 313   *stack_begin = t->stack_bottom();
 314   *stack_end = t->stack_top();
 315   *tls_begin = t->tls_begin();
 316   *tls_end = t->tls_end();
 317   // ASan doesn't keep allocator caches in TLS, so these are unused.
 318   *cache_begin = 0;
 319   *cache_end = 0;
 320   return true;
 321 }
 322
 323 void ForEachExtraStackRange(uptr os_id, RangeIteratorCallback callback,
 324                             void *arg) {
 325   __asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id);
 326   if (t && t->has_fake_stack())
 327     t->fake_stack()->ForEachFakeFrame(callback, arg);
 328 }
 329
 330 void LockThreadRegistry() {
 331   __asan::asanThreadRegistry().Lock();
 332 }
 333
 334 void UnlockThreadRegistry() {
 335   __asan::asanThreadRegistry().Unlock();
 336 }
 337
 338 void EnsureMainThreadIDIsCorrect() {
 339   __asan::EnsureMainThreadIDIsCorrect();
 340 }
 341 }  // namespace __lsan