asan_thread.cc revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0
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 26namespace __asan { 27 28// AsanThreadContext implementation. 29 30void 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 38void AsanThreadContext::OnFinished() { 39 // Drop the link to the AsanThread object. 40 thread = 0; 41} 42 43// MIPS requires aligned address 44static ALIGNED(16) char thread_registry_placeholder[sizeof(ThreadRegistry)]; 45static ThreadRegistry *asan_thread_registry; 46 47static BlockingMutex mu_for_thread_context(LINKER_INITIALIZED); 48static LowLevelAllocator allocator_for_thread_context; 49 50static ThreadContextBase *GetAsanThreadContext(u32 tid) { 51 BlockingMutexLock lock(&mu_for_thread_context); 52 return new(allocator_for_thread_context) AsanThreadContext(tid); 53} 54 55ThreadRegistry &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 71AsanThreadContext *GetThreadContextByTidLocked(u32 tid) { 72 return static_cast<AsanThreadContext *>( 73 asanThreadRegistry().GetThreadLocked(tid)); 74} 75 76// AsanThread implementation. 77 78AsanThread *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 89void 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 96void 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. 116FakeStack *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 143void 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 156thread_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 182void 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 193void 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 199const 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 237static 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 248AsanThread *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 269void 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 279u32 GetCurrentTidOrInvalid() { 280 AsanThread *t = GetCurrentThread(); 281 return t ? t->tid() : kInvalidTid; 282} 283 284AsanThread *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 292void 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 308namespace __lsan { 309bool 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 324void 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 331void LockThreadRegistry() { 332 __asan::asanThreadRegistry().Lock(); 333} 334 335void UnlockThreadRegistry() { 336 __asan::asanThreadRegistry().Unlock(); 337} 338 339void EnsureMainThreadIDIsCorrect() { 340 __asan::EnsureMainThreadIDIsCorrect(); 341} 342} // namespace __lsan 343