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 "sanitizer_common/sanitizer_tls_get_addr.h"
  22 #include "lsan/lsan_common.h"
  23
  24 namespace __asan {
  25
  26 // AsanThreadContext implementation.
  27
  28 struct CreateThreadContextArgs {
  29   AsanThread *thread;
  30   StackTrace *stack;
  31 };
  32
  33 void AsanThreadContext::OnCreated(void *arg) {
  34   CreateThreadContextArgs *args = static_cast<CreateThreadContextArgs*>(arg);
  35   if (args->stack)
  36     stack_id = StackDepotPut(*args->stack);
  37   thread = args->thread;
  38   thread->set_context(this);
  39 }
  40
  41 void AsanThreadContext::OnFinished() {
  42   // Drop the link to the AsanThread object.
  43   thread = nullptr;
  44 }
  45
  46 // MIPS requires aligned address
  47 static ALIGNED(16) char thread_registry_placeholder[sizeof(ThreadRegistry)];
  48 static ThreadRegistry *asan_thread_registry;
  49
  50 static BlockingMutex mu_for_thread_context(LINKER_INITIALIZED);
  51 static LowLevelAllocator allocator_for_thread_context;
  52
  53 static ThreadContextBase *GetAsanThreadContext(u32 tid) {
  54   BlockingMutexLock lock(&mu_for_thread_context);
  55   return new(allocator_for_thread_context) AsanThreadContext(tid);
  56 }
  57
  58 ThreadRegistry &asanThreadRegistry() {
  59   static bool initialized;
  60   // Don't worry about thread_safety - this should be called when there is
  61   // a single thread.
  62   if (!initialized) {
  63     // Never reuse ASan threads: we store pointer to AsanThreadContext
  64     // in TSD and can't reliably tell when no more TSD destructors will
  65     // be called. It would be wrong to reuse AsanThreadContext for another
  66     // thread before all TSD destructors will be called for it.
  67     asan_thread_registry = new(thread_registry_placeholder) ThreadRegistry(
  68         GetAsanThreadContext, kMaxNumberOfThreads, kMaxNumberOfThreads);
  69     initialized = true;
  70   }
  71   return *asan_thread_registry;
  72 }
  73
  74 AsanThreadContext *GetThreadContextByTidLocked(u32 tid) {
  75   return static_cast<AsanThreadContext *>(
  76       asanThreadRegistry().GetThreadLocked(tid));
  77 }
  78
  79 // AsanThread implementation.
  80
  81 AsanThread *AsanThread::Create(thread_callback_t start_routine, void *arg,
  82                                u32 parent_tid, StackTrace *stack,
  83                                bool detached) {
  84   uptr PageSize = GetPageSizeCached();
  85   uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
  86   AsanThread *thread = (AsanThread*)MmapOrDie(size, __func__);
  87   thread->start_routine_ = start_routine;
  88   thread->arg_ = arg;
  89   CreateThreadContextArgs args = { thread, stack };
  90   asanThreadRegistry().CreateThread(*reinterpret_cast<uptr *>(thread), detached,
  91                                     parent_tid, &args);
  92
  93   return thread;
  94 }
  95
  96 void AsanThread::TSDDtor(void *tsd) {
  97   AsanThreadContext *context = (AsanThreadContext*)tsd;
  98   VReport(1, "T%d TSDDtor\n", context->tid);
  99   if (context->thread)
 100     context->thread->Destroy();
 101 }
 102
 103 void AsanThread::Destroy() {
 104   int tid = this->tid();
 105   VReport(1, "T%d exited\n", tid);
 106
 107   malloc_storage().CommitBack();
 108   if (common_flags()->use_sigaltstack) UnsetAlternateSignalStack();
 109   asanThreadRegistry().FinishThread(tid);
 110   FlushToDeadThreadStats(&stats_);
 111   // We also clear the shadow on thread destruction because
 112   // some code may still be executing in later TSD destructors
 113   // and we don't want it to have any poisoned stack.
 114   ClearShadowForThreadStackAndTLS();
 115   DeleteFakeStack(tid);
 116   uptr size = RoundUpTo(sizeof(AsanThread), GetPageSizeCached());
 117   UnmapOrDie(this, size);
 118   DTLS_Destroy();
 119 }
 120
 121 // We want to create the FakeStack lazyly on the first use, but not eralier
 122 // than the stack size is known and the procedure has to be async-signal safe.
 123 FakeStack *AsanThread::AsyncSignalSafeLazyInitFakeStack() {
 124   uptr stack_size = this->stack_size();
 125   if (stack_size == 0)  // stack_size is not yet available, don't use FakeStack.
 126     return nullptr;
 127   uptr old_val = 0;
 128   // fake_stack_ has 3 states:
 129   // 0   -- not initialized
 130   // 1   -- being initialized
 131   // ptr -- initialized
 132   // This CAS checks if the state was 0 and if so changes it to state 1,
 133   // if that was successful, it initializes the pointer.
 134   if (atomic_compare_exchange_strong(
 135       reinterpret_cast<atomic_uintptr_t *>(&fake_stack_), &old_val, 1UL,
 136       memory_order_relaxed)) {
 137     uptr stack_size_log = Log2(RoundUpToPowerOfTwo(stack_size));
 138     CHECK_LE(flags()->min_uar_stack_size_log, flags()->max_uar_stack_size_log);
 139     stack_size_log =
 140         Min(stack_size_log, static_cast<uptr>(flags()->max_uar_stack_size_log));
 141     stack_size_log =
 142         Max(stack_size_log, static_cast<uptr>(flags()->min_uar_stack_size_log));
 143     fake_stack_ = FakeStack::Create(stack_size_log);
 144     SetTLSFakeStack(fake_stack_);
 145     return fake_stack_;
 146   }
 147   return nullptr;
 148 }
 149
 150 void AsanThread::Init() {
 151   fake_stack_ = nullptr;  // Will be initialized lazily if needed.
 152   CHECK_EQ(this->stack_size(), 0U);
 153   SetThreadStackAndTls();
 154   CHECK_GT(this->stack_size(), 0U);
 155   CHECK(AddrIsInMem(stack_bottom_));
 156   CHECK(AddrIsInMem(stack_top_ - 1));
 157   ClearShadowForThreadStackAndTLS();
 158   int local = 0;
 159   VReport(1, "T%d: stack [%p,%p) size 0x%zx; local=%p\n", tid(),
 160           (void *)stack_bottom_, (void *)stack_top_, stack_top_ - stack_bottom_,
 161           &local);
 162 }
 163
 164 thread_return_t AsanThread::ThreadStart(
 165     uptr os_id, atomic_uintptr_t *signal_thread_is_registered) {
 166   Init();
 167   asanThreadRegistry().StartThread(tid(), os_id, nullptr);
 168   if (signal_thread_is_registered)
 169     atomic_store(signal_thread_is_registered, 1, memory_order_release);
 170
 171   if (common_flags()->use_sigaltstack) SetAlternateSignalStack();
 172
 173   if (!start_routine_) {
 174     // start_routine_ == 0 if we're on the main thread or on one of the
 175     // OS X libdispatch worker threads. But nobody is supposed to call
 176     // ThreadStart() for the worker threads.
 177     CHECK_EQ(tid(), 0);
 178     return 0;
 179   }
 180
 181   thread_return_t res = start_routine_(arg_);
 182
 183   // On POSIX systems we defer this to the TSD destructor. LSan will consider
 184   // the thread's memory as non-live from the moment we call Destroy(), even
 185   // though that memory might contain pointers to heap objects which will be
 186   // cleaned up by a user-defined TSD destructor. Thus, calling Destroy() before
 187   // the TSD destructors have run might cause false positives in LSan.
 188   if (!SANITIZER_POSIX)
 189     this->Destroy();
 190
 191   return res;
 192 }
 193
 194 void AsanThread::SetThreadStackAndTls() {
 195   uptr tls_size = 0;
 196   GetThreadStackAndTls(tid() == 0, &stack_bottom_, &stack_size_, &tls_begin_,
 197                        &tls_size);
 198   stack_top_ = stack_bottom_ + stack_size_;
 199   tls_end_ = tls_begin_ + tls_size;
 200
 201   int local;
 202   CHECK(AddrIsInStack((uptr)&local));
 203 }
 204
 205 void AsanThread::ClearShadowForThreadStackAndTLS() {
 206   PoisonShadow(stack_bottom_, stack_top_ - stack_bottom_, 0);
 207   if (tls_begin_ != tls_end_)
 208     PoisonShadow(tls_begin_, tls_end_ - tls_begin_, 0);
 209 }
 210
 211 bool AsanThread::GetStackFrameAccessByAddr(uptr addr,
 212                                            StackFrameAccess *access) {
 213   uptr bottom = 0;
 214   if (AddrIsInStack(addr)) {
 215     bottom = stack_bottom();
 216   } else if (has_fake_stack()) {
 217     bottom = fake_stack()->AddrIsInFakeStack(addr);
 218     CHECK(bottom);
 219     access->offset = addr - bottom;
 220     access->frame_pc = ((uptr*)bottom)[2];
 221     access->frame_descr = (const char *)((uptr*)bottom)[1];
 222     return true;
 223   }
 224   uptr aligned_addr = addr & ~(SANITIZER_WORDSIZE/8 - 1);  // align addr.
 225   u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
 226   u8 *shadow_bottom = (u8*)MemToShadow(bottom);
 227
 228   while (shadow_ptr >= shadow_bottom &&
 229          *shadow_ptr != kAsanStackLeftRedzoneMagic) {
 230     shadow_ptr--;
 231   }
 232
 233   while (shadow_ptr >= shadow_bottom &&
 234          *shadow_ptr == kAsanStackLeftRedzoneMagic) {
 235     shadow_ptr--;
 236   }
 237
 238   if (shadow_ptr < shadow_bottom) {
 239     return false;
 240   }
 241
 242   uptr* ptr = (uptr*)SHADOW_TO_MEM((uptr)(shadow_ptr + 1));
 243   CHECK(ptr[0] == kCurrentStackFrameMagic);
 244   access->offset = addr - (uptr)ptr;
 245   access->frame_pc = ptr[2];
 246   access->frame_descr = (const char*)ptr[1];
 247   return true;
 248 }
 249
 250 static bool ThreadStackContainsAddress(ThreadContextBase *tctx_base,
 251                                        void *addr) {
 252   AsanThreadContext *tctx = static_cast<AsanThreadContext*>(tctx_base);
 253   AsanThread *t = tctx->thread;
 254   if (!t) return false;
 255   if (t->AddrIsInStack((uptr)addr)) return true;
 256   if (t->has_fake_stack() && t->fake_stack()->AddrIsInFakeStack((uptr)addr))
 257     return true;
 258   return false;
 259 }
 260
 261 AsanThread *GetCurrentThread() {
 262   AsanThreadContext *context =
 263       reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
 264   if (!context) {
 265     if (SANITIZER_ANDROID) {
 266       // On Android, libc constructor is called _after_ asan_init, and cleans up
 267       // TSD. Try to figure out if this is still the main thread by the stack
 268       // address. We are not entirely sure that we have correct main thread
 269       // limits, so only do this magic on Android, and only if the found thread
 270       // is the main thread.
 271       AsanThreadContext *tctx = GetThreadContextByTidLocked(0);
 272       if (ThreadStackContainsAddress(tctx, &context)) {
 273         SetCurrentThread(tctx->thread);
 274         return tctx->thread;
 275       }
 276     }
 277     return nullptr;
 278   }
 279   return context->thread;
 280 }
 281
 282 void SetCurrentThread(AsanThread *t) {
 283   CHECK(t->context());
 284   VReport(2, "SetCurrentThread: %p for thread %p\n", t->context(),
 285           (void *)GetThreadSelf());
 286   // Make sure we do not reset the current AsanThread.
 287   CHECK_EQ(0, AsanTSDGet());
 288   AsanTSDSet(t->context());
 289   CHECK_EQ(t->context(), AsanTSDGet());
 290 }
 291
 292 u32 GetCurrentTidOrInvalid() {
 293   AsanThread *t = GetCurrentThread();
 294   return t ? t->tid() : kInvalidTid;
 295 }
 296
 297 AsanThread *FindThreadByStackAddress(uptr addr) {
 298   asanThreadRegistry().CheckLocked();
 299   AsanThreadContext *tctx = static_cast<AsanThreadContext *>(
 300       asanThreadRegistry().FindThreadContextLocked(ThreadStackContainsAddress,
 301                                                    (void *)addr));
 302   return tctx ? tctx->thread : nullptr;
 303 }
 304
 305 void EnsureMainThreadIDIsCorrect() {
 306   AsanThreadContext *context =
 307       reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
 308   if (context && (context->tid == 0))
 309     context->os_id = GetTid();
 310 }
 311
 312 __asan::AsanThread *GetAsanThreadByOsIDLocked(uptr os_id) {
 313   __asan::AsanThreadContext *context = static_cast<__asan::AsanThreadContext *>(
 314       __asan::asanThreadRegistry().FindThreadContextByOsIDLocked(os_id));
 315   if (!context) return nullptr;
 316   return context->thread;
 317 }
 318 } // namespace __asan
 319
 320 // --- Implementation of LSan-specific functions --- {{{1
 321 namespace __lsan {
 322 bool GetThreadRangesLocked(uptr os_id, uptr *stack_begin, uptr *stack_end,
 323                            uptr *tls_begin, uptr *tls_end,
 324                            uptr *cache_begin, uptr *cache_end) {
 325   __asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id);
 326   if (!t) return false;
 327   *stack_begin = t->stack_bottom();
 328   *stack_end = t->stack_top();
 329   *tls_begin = t->tls_begin();
 330   *tls_end = t->tls_end();
 331   // ASan doesn't keep allocator caches in TLS, so these are unused.
 332   *cache_begin = 0;
 333   *cache_end = 0;
 334   return true;
 335 }
 336
 337 void ForEachExtraStackRange(uptr os_id, RangeIteratorCallback callback,
 338                             void *arg) {
 339   __asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id);
 340   if (t && t->has_fake_stack())
 341     t->fake_stack()->ForEachFakeFrame(callback, arg);
 342 }
 343
 344 void LockThreadRegistry() {
 345   __asan::asanThreadRegistry().Lock();
 346 }
 347
 348 void UnlockThreadRegistry() {
 349   __asan::asanThreadRegistry().Unlock();
 350 }
 351
 352 void EnsureMainThreadIDIsCorrect() {
 353   __asan::EnsureMainThreadIDIsCorrect();
 354 }
 355 } // namespace __lsan