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