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 successful, it initializes 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 fake_stack_ = 0; // Will be initialized lazily if needed. 145 CHECK_EQ(this->stack_size(), 0U); 146 SetThreadStackAndTls(); 147 CHECK_GT(this->stack_size(), 0U); 148 CHECK(AddrIsInMem(stack_bottom_)); 149 CHECK(AddrIsInMem(stack_top_ - 1)); 150 ClearShadowForThreadStackAndTLS(); 151 int local = 0; 152 VReport(1, "T%d: stack [%p,%p) size 0x%zx; local=%p\n", tid(), 153 (void *)stack_bottom_, (void *)stack_top_, stack_top_ - stack_bottom_, 154 &local); 155 AsanPlatformThreadInit(); 156 } 157 158 thread_return_t AsanThread::ThreadStart(uptr os_id) { 159 Init(); 160 asanThreadRegistry().StartThread(tid(), os_id, 0); 161 if (common_flags()->use_sigaltstack) SetAlternateSignalStack(); 162 163 if (!start_routine_) { 164 // start_routine_ == 0 if we're on the main thread or on one of the 165 // OS X libdispatch worker threads. But nobody is supposed to call 166 // ThreadStart() for the worker threads. 167 CHECK_EQ(tid(), 0); 168 return 0; 169 } 170 171 thread_return_t res = start_routine_(arg_); 172 173 // On POSIX systems we defer this to the TSD destructor. LSan will consider 174 // the thread's memory as non-live from the moment we call Destroy(), even 175 // though that memory might contain pointers to heap objects which will be 176 // cleaned up by a user-defined TSD destructor. Thus, calling Destroy() before 177 // the TSD destructors have run might cause false positives in LSan. 178 if (!SANITIZER_POSIX) 179 this->Destroy(); 180 181 return res; 182 } 183 184 void AsanThread::SetThreadStackAndTls() { 185 uptr tls_size = 0; 186 GetThreadStackAndTls(tid() == 0, &stack_bottom_, &stack_size_, &tls_begin_, 187 &tls_size); 188 stack_top_ = stack_bottom_ + stack_size_; 189 tls_end_ = tls_begin_ + tls_size; 190 191 int local; 192 CHECK(AddrIsInStack((uptr)&local)); 193 } 194 195 void AsanThread::ClearShadowForThreadStackAndTLS() { 196 PoisonShadow(stack_bottom_, stack_top_ - stack_bottom_, 0); 197 if (tls_begin_ != tls_end_) 198 PoisonShadow(tls_begin_, tls_end_ - tls_begin_, 0); 199 } 200 201 const char *AsanThread::GetFrameNameByAddr(uptr addr, uptr *offset, 202 uptr *frame_pc) { 203 uptr bottom = 0; 204 if (AddrIsInStack(addr)) { 205 bottom = stack_bottom(); 206 } else if (has_fake_stack()) { 207 bottom = fake_stack()->AddrIsInFakeStack(addr); 208 CHECK(bottom); 209 *offset = addr - bottom; 210 *frame_pc = ((uptr*)bottom)[2]; 211 return (const char *)((uptr*)bottom)[1]; 212 } 213 uptr aligned_addr = addr & ~(SANITIZER_WORDSIZE/8 - 1); // align addr. 214 u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr); 215 u8 *shadow_bottom = (u8*)MemToShadow(bottom); 216 217 while (shadow_ptr >= shadow_bottom && 218 *shadow_ptr != kAsanStackLeftRedzoneMagic) { 219 shadow_ptr--; 220 } 221 222 while (shadow_ptr >= shadow_bottom && 223 *shadow_ptr == kAsanStackLeftRedzoneMagic) { 224 shadow_ptr--; 225 } 226 227 if (shadow_ptr < shadow_bottom) { 228 *offset = 0; 229 return "UNKNOWN"; 230 } 231 232 uptr* ptr = (uptr*)SHADOW_TO_MEM((uptr)(shadow_ptr + 1)); 233 CHECK(ptr[0] == kCurrentStackFrameMagic); 234 *offset = addr - (uptr)ptr; 235 *frame_pc = ptr[2]; 236 return (const char*)ptr[1]; 237 } 238 239 static bool ThreadStackContainsAddress(ThreadContextBase *tctx_base, 240 void *addr) { 241 AsanThreadContext *tctx = static_cast<AsanThreadContext*>(tctx_base); 242 AsanThread *t = tctx->thread; 243 if (!t) return false; 244 if (t->AddrIsInStack((uptr)addr)) return true; 245 if (t->has_fake_stack() && t->fake_stack()->AddrIsInFakeStack((uptr)addr)) 246 return true; 247 return false; 248 } 249 250 AsanThread *GetCurrentThread() { 251 AsanThreadContext *context = 252 reinterpret_cast<AsanThreadContext *>(AsanTSDGet()); 253 if (!context) { 254 if (SANITIZER_ANDROID) { 255 // On Android, libc constructor is called _after_ asan_init, and cleans up 256 // TSD. Try to figure out if this is still the main thread by the stack 257 // address. We are not entirely sure that we have correct main thread 258 // limits, so only do this magic on Android, and only if the found thread 259 // is the main thread. 260 AsanThreadContext *tctx = GetThreadContextByTidLocked(0); 261 if (ThreadStackContainsAddress(tctx, &context)) { 262 SetCurrentThread(tctx->thread); 263 return tctx->thread; 264 } 265 } 266 return 0; 267 } 268 return context->thread; 269 } 270 271 void SetCurrentThread(AsanThread *t) { 272 CHECK(t->context()); 273 VReport(2, "SetCurrentThread: %p for thread %p\n", t->context(), 274 (void *)GetThreadSelf()); 275 // Make sure we do not reset the current AsanThread. 276 CHECK_EQ(0, AsanTSDGet()); 277 AsanTSDSet(t->context()); 278 CHECK_EQ(t->context(), AsanTSDGet()); 279 } 280 281 u32 GetCurrentTidOrInvalid() { 282 AsanThread *t = GetCurrentThread(); 283 return t ? t->tid() : kInvalidTid; 284 } 285 286 AsanThread *FindThreadByStackAddress(uptr addr) { 287 asanThreadRegistry().CheckLocked(); 288 AsanThreadContext *tctx = static_cast<AsanThreadContext *>( 289 asanThreadRegistry().FindThreadContextLocked(ThreadStackContainsAddress, 290 (void *)addr)); 291 return tctx ? tctx->thread : 0; 292 } 293 294 void EnsureMainThreadIDIsCorrect() { 295 AsanThreadContext *context = 296 reinterpret_cast<AsanThreadContext *>(AsanTSDGet()); 297 if (context && (context->tid == 0)) 298 context->os_id = GetTid(); 299 } 300 301 __asan::AsanThread *GetAsanThreadByOsIDLocked(uptr os_id) { 302 __asan::AsanThreadContext *context = static_cast<__asan::AsanThreadContext *>( 303 __asan::asanThreadRegistry().FindThreadContextByOsIDLocked(os_id)); 304 if (!context) return 0; 305 return context->thread; 306 } 307 } // namespace __asan 308 309 // --- Implementation of LSan-specific functions --- {{{1 310 namespace __lsan { 311 bool GetThreadRangesLocked(uptr os_id, uptr *stack_begin, uptr *stack_end, 312 uptr *tls_begin, uptr *tls_end, 313 uptr *cache_begin, uptr *cache_end) { 314 __asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id); 315 if (!t) return false; 316 *stack_begin = t->stack_bottom(); 317 *stack_end = t->stack_top(); 318 *tls_begin = t->tls_begin(); 319 *tls_end = t->tls_end(); 320 // ASan doesn't keep allocator caches in TLS, so these are unused. 321 *cache_begin = 0; 322 *cache_end = 0; 323 return true; 324 } 325 326 void ForEachExtraStackRange(uptr os_id, RangeIteratorCallback callback, 327 void *arg) { 328 __asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id); 329 if (t && t->has_fake_stack()) 330 t->fake_stack()->ForEachFakeFrame(callback, arg); 331 } 332 333 void LockThreadRegistry() { 334 __asan::asanThreadRegistry().Lock(); 335 } 336 337 void UnlockThreadRegistry() { 338 __asan::asanThreadRegistry().Unlock(); 339 } 340 341 void EnsureMainThreadIDIsCorrect() { 342 __asan::EnsureMainThreadIDIsCorrect(); 343 } 344 } // namespace __lsan 345
