lib/asan/asan_thread.cc

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