libsanitizer/tsan/tsan_rtl_report.cpp

   1 //===-- tsan_rtl_report.cpp -----------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of ThreadSanitizer (TSan), a race detector.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "sanitizer_common/sanitizer_common.h"
  14 #include "sanitizer_common/sanitizer_libc.h"
  15 #include "sanitizer_common/sanitizer_placement_new.h"
  16 #include "sanitizer_common/sanitizer_stackdepot.h"
  17 #include "sanitizer_common/sanitizer_stacktrace.h"
  18 #include "tsan_fd.h"
  19 #include "tsan_flags.h"
  20 #include "tsan_mman.h"
  21 #include "tsan_platform.h"
  22 #include "tsan_report.h"
  23 #include "tsan_rtl.h"
  24 #include "tsan_suppressions.h"
  25 #include "tsan_symbolize.h"
  26 #include "tsan_sync.h"
  27
  28 namespace __tsan {
  29
  30 using namespace __sanitizer;
  31
  32 static ReportStack *SymbolizeStack(StackTrace trace);
  33
  34 // Can be overriden by an application/test to intercept reports.
  35 #ifdef TSAN_EXTERNAL_HOOKS
  36 bool OnReport(const ReportDesc *rep, bool suppressed);
  37 #else
  38 SANITIZER_WEAK_CXX_DEFAULT_IMPL
  39 bool OnReport(const ReportDesc *rep, bool suppressed) {
  40   (void)rep;
  41   return suppressed;
  42 }
  43 #endif
  44
  45 SANITIZER_WEAK_DEFAULT_IMPL
  46 void __tsan_on_report(const ReportDesc *rep) {
  47   (void)rep;
  48 }
  49
  50 static void StackStripMain(SymbolizedStack *frames) {
  51   SymbolizedStack *last_frame = nullptr;
  52   SymbolizedStack *last_frame2 = nullptr;
  53   for (SymbolizedStack *cur = frames; cur; cur = cur->next) {
  54     last_frame2 = last_frame;
  55     last_frame = cur;
  56   }
  57
  58   if (last_frame2 == 0)
  59     return;
  60 #if !SANITIZER_GO
  61   const char *last = last_frame->info.function;
  62   const char *last2 = last_frame2->info.function;
  63   // Strip frame above 'main'
  64   if (last2 && 0 == internal_strcmp(last2, "main")) {
  65     last_frame->ClearAll();
  66     last_frame2->next = nullptr;
  67   // Strip our internal thread start routine.
  68   } else if (last && 0 == internal_strcmp(last, "__tsan_thread_start_func")) {
  69     last_frame->ClearAll();
  70     last_frame2->next = nullptr;
  71     // Strip global ctors init, .preinit_array and main caller.
  72   } else if (last && (0 == internal_strcmp(last, "__do_global_ctors_aux") ||
  73                       0 == internal_strcmp(last, "__libc_csu_init") ||
  74                       0 == internal_strcmp(last, "__libc_start_main"))) {
  75     last_frame->ClearAll();
  76     last_frame2->next = nullptr;
  77   // If both are 0, then we probably just failed to symbolize.
  78   } else if (last || last2) {
  79     // Ensure that we recovered stack completely. Trimmed stack
  80     // can actually happen if we do not instrument some code,
  81     // so it's only a debug print. However we must try hard to not miss it
  82     // due to our fault.
  83     DPrintf("Bottom stack frame is missed\n");
  84   }
  85 #else
  86   // The last frame always point into runtime (gosched0, goexit0, runtime.main).
  87   last_frame->ClearAll();
  88   last_frame2->next = nullptr;
  89 #endif
  90 }
  91
  92 ReportStack *SymbolizeStackId(u32 stack_id) {
  93   if (stack_id == 0)
  94     return 0;
  95   StackTrace stack = StackDepotGet(stack_id);
  96   if (stack.trace == nullptr)
  97     return nullptr;
  98   return SymbolizeStack(stack);
  99 }
 100
 101 static ReportStack *SymbolizeStack(StackTrace trace) {
 102   if (trace.size == 0)
 103     return 0;
 104   SymbolizedStack *top = nullptr;
 105   for (uptr si = 0; si < trace.size; si++) {
 106     const uptr pc = trace.trace[si];
 107     uptr pc1 = pc;
 108     // We obtain the return address, but we're interested in the previous
 109     // instruction.
 110     if ((pc & kExternalPCBit) == 0)
 111       pc1 = StackTrace::GetPreviousInstructionPc(pc);
 112     SymbolizedStack *ent = SymbolizeCode(pc1);
 113     CHECK_NE(ent, 0);
 114     SymbolizedStack *last = ent;
 115     while (last->next) {
 116       last->info.address = pc;  // restore original pc for report
 117       last = last->next;
 118     }
 119     last->info.address = pc;  // restore original pc for report
 120     last->next = top;
 121     top = ent;
 122   }
 123   StackStripMain(top);
 124
 125   auto *stack = New<ReportStack>();
 126   stack->frames = top;
 127   return stack;
 128 }
 129
 130 bool ShouldReport(ThreadState *thr, ReportType typ) {
 131   // We set thr->suppress_reports in the fork context.
 132   // Taking any locking in the fork context can lead to deadlocks.
 133   // If any locks are already taken, it's too late to do this check.
 134   CheckedMutex::CheckNoLocks();
 135   // For the same reason check we didn't lock thread_registry yet.
 136   if (SANITIZER_DEBUG)
 137     ThreadRegistryLock l(&ctx->thread_registry);
 138   if (!flags()->report_bugs || thr->suppress_reports)
 139     return false;
 140   switch (typ) {
 141     case ReportTypeSignalUnsafe:
 142       return flags()->report_signal_unsafe;
 143     case ReportTypeThreadLeak:
 144 #if !SANITIZER_GO
 145       // It's impossible to join phantom threads
 146       // in the child after fork.
 147       if (ctx->after_multithreaded_fork)
 148         return false;
 149 #endif
 150       return flags()->report_thread_leaks;
 151     case ReportTypeMutexDestroyLocked:
 152       return flags()->report_destroy_locked;
 153     default:
 154       return true;
 155   }
 156 }
 157
 158 ScopedReportBase::ScopedReportBase(ReportType typ, uptr tag) {
 159   ctx->thread_registry.CheckLocked();
 160   rep_ = New<ReportDesc>();
 161   rep_->typ = typ;
 162   rep_->tag = tag;
 163   ctx->report_mtx.Lock();
 164 }
 165
 166 ScopedReportBase::~ScopedReportBase() {
 167   ctx->report_mtx.Unlock();
 168   DestroyAndFree(rep_);
 169 }
 170
 171 void ScopedReportBase::AddStack(StackTrace stack, bool suppressable) {
 172   ReportStack **rs = rep_->stacks.PushBack();
 173   *rs = SymbolizeStack(stack);
 174   (*rs)->suppressable = suppressable;
 175 }
 176
 177 void ScopedReportBase::AddMemoryAccess(uptr addr, uptr external_tag, Shadow s,
 178                                        Tid tid, StackTrace stack,
 179                                        const MutexSet *mset) {
 180   uptr addr0, size;
 181   AccessType typ;
 182   s.GetAccess(&addr0, &size, &typ);
 183   auto *mop = New<ReportMop>();
 184   rep_->mops.PushBack(mop);
 185   mop->tid = tid;
 186   mop->addr = addr + addr0;
 187   mop->size = size;
 188   mop->write = !(typ & kAccessRead);
 189   mop->atomic = typ & kAccessAtomic;
 190   mop->stack = SymbolizeStack(stack);
 191   mop->external_tag = external_tag;
 192   if (mop->stack)
 193     mop->stack->suppressable = true;
 194   for (uptr i = 0; i < mset->Size(); i++) {
 195     MutexSet::Desc d = mset->Get(i);
 196     int id = this->AddMutex(d.addr, d.stack_id);
 197     ReportMopMutex mtx = {id, d.write};
 198     mop->mset.PushBack(mtx);
 199   }
 200 }
 201
 202 void ScopedReportBase::AddUniqueTid(Tid unique_tid) {
 203   rep_->unique_tids.PushBack(unique_tid);
 204 }
 205
 206 void ScopedReportBase::AddThread(const ThreadContext *tctx, bool suppressable) {
 207   for (uptr i = 0; i < rep_->threads.Size(); i++) {
 208     if ((u32)rep_->threads[i]->id == tctx->tid)
 209       return;
 210   }
 211   auto *rt = New<ReportThread>();
 212   rep_->threads.PushBack(rt);
 213   rt->id = tctx->tid;
 214   rt->os_id = tctx->os_id;
 215   rt->running = (tctx->status == ThreadStatusRunning);
 216   rt->name = internal_strdup(tctx->name);
 217   rt->parent_tid = tctx->parent_tid;
 218   rt->thread_type = tctx->thread_type;
 219   rt->stack = 0;
 220   rt->stack = SymbolizeStackId(tctx->creation_stack_id);
 221   if (rt->stack)
 222     rt->stack->suppressable = suppressable;
 223 }
 224
 225 #if !SANITIZER_GO
 226 static ThreadContext *FindThreadByTidLocked(Tid tid) {
 227   ctx->thread_registry.CheckLocked();
 228   return static_cast<ThreadContext *>(
 229       ctx->thread_registry.GetThreadLocked(tid));
 230 }
 231
 232 static bool IsInStackOrTls(ThreadContextBase *tctx_base, void *arg) {
 233   uptr addr = (uptr)arg;
 234   ThreadContext *tctx = static_cast<ThreadContext*>(tctx_base);
 235   if (tctx->status != ThreadStatusRunning)
 236     return false;
 237   ThreadState *thr = tctx->thr;
 238   CHECK(thr);
 239   return ((addr >= thr->stk_addr && addr < thr->stk_addr + thr->stk_size) ||
 240           (addr >= thr->tls_addr && addr < thr->tls_addr + thr->tls_size));
 241 }
 242
 243 ThreadContext *IsThreadStackOrTls(uptr addr, bool *is_stack) {
 244   ctx->thread_registry.CheckLocked();
 245   ThreadContext *tctx =
 246       static_cast<ThreadContext *>(ctx->thread_registry.FindThreadContextLocked(
 247           IsInStackOrTls, (void *)addr));
 248   if (!tctx)
 249     return 0;
 250   ThreadState *thr = tctx->thr;
 251   CHECK(thr);
 252   *is_stack = (addr >= thr->stk_addr && addr < thr->stk_addr + thr->stk_size);
 253   return tctx;
 254 }
 255 #endif
 256
 257 void ScopedReportBase::AddThread(Tid tid, bool suppressable) {
 258 #if !SANITIZER_GO
 259   if (const ThreadContext *tctx = FindThreadByTidLocked(tid))
 260     AddThread(tctx, suppressable);
 261 #endif
 262 }
 263
 264 int ScopedReportBase::AddMutex(uptr addr, StackID creation_stack_id) {
 265   for (uptr i = 0; i < rep_->mutexes.Size(); i++) {
 266     if (rep_->mutexes[i]->addr == addr)
 267       return rep_->mutexes[i]->id;
 268   }
 269   auto *rm = New<ReportMutex>();
 270   rep_->mutexes.PushBack(rm);
 271   rm->id = rep_->mutexes.Size() - 1;
 272   rm->addr = addr;
 273   rm->stack = SymbolizeStackId(creation_stack_id);
 274   return rm->id;
 275 }
 276
 277 void ScopedReportBase::AddLocation(uptr addr, uptr size) {
 278   if (addr == 0)
 279     return;
 280 #if !SANITIZER_GO
 281   int fd = -1;
 282   Tid creat_tid = kInvalidTid;
 283   StackID creat_stack = 0;
 284   bool closed = false;
 285   if (FdLocation(addr, &fd, &creat_tid, &creat_stack, &closed)) {
 286     auto *loc = New<ReportLocation>();
 287     loc->type = ReportLocationFD;
 288     loc->fd_closed = closed;
 289     loc->fd = fd;
 290     loc->tid = creat_tid;
 291     loc->stack = SymbolizeStackId(creat_stack);
 292     rep_->locs.PushBack(loc);
 293     AddThread(creat_tid);
 294     return;
 295   }
 296   MBlock *b = 0;
 297   uptr block_begin = 0;
 298   Allocator *a = allocator();
 299   if (a->PointerIsMine((void*)addr)) {
 300     block_begin = (uptr)a->GetBlockBegin((void *)addr);
 301     if (block_begin)
 302       b = ctx->metamap.GetBlock(block_begin);
 303   }
 304   if (!b)
 305     b = JavaHeapBlock(addr, &block_begin);
 306   if (b != 0) {
 307     auto *loc = New<ReportLocation>();
 308     loc->type = ReportLocationHeap;
 309     loc->heap_chunk_start = block_begin;
 310     loc->heap_chunk_size = b->siz;
 311     loc->external_tag = b->tag;
 312     loc->tid = b->tid;
 313     loc->stack = SymbolizeStackId(b->stk);
 314     rep_->locs.PushBack(loc);
 315     AddThread(b->tid);
 316     return;
 317   }
 318   bool is_stack = false;
 319   if (ThreadContext *tctx = IsThreadStackOrTls(addr, &is_stack)) {
 320     auto *loc = New<ReportLocation>();
 321     loc->type = is_stack ? ReportLocationStack : ReportLocationTLS;
 322     loc->tid = tctx->tid;
 323     rep_->locs.PushBack(loc);
 324     AddThread(tctx);
 325   }
 326 #endif
 327   if (ReportLocation *loc = SymbolizeData(addr)) {
 328     loc->suppressable = true;
 329     rep_->locs.PushBack(loc);
 330     return;
 331   }
 332 }
 333
 334 #if !SANITIZER_GO
 335 void ScopedReportBase::AddSleep(StackID stack_id) {
 336   rep_->sleep = SymbolizeStackId(stack_id);
 337 }
 338 #endif
 339
 340 void ScopedReportBase::SetCount(int count) { rep_->count = count; }
 341
 342 void ScopedReportBase::SetSigNum(int sig) { rep_->signum = sig; }
 343
 344 const ReportDesc *ScopedReportBase::GetReport() const { return rep_; }
 345
 346 ScopedReport::ScopedReport(ReportType typ, uptr tag)
 347     : ScopedReportBase(typ, tag) {}
 348
 349 ScopedReport::~ScopedReport() {}
 350
 351 // Replays the trace up to last_pos position in the last part
 352 // or up to the provided epoch/sid (whichever is earlier)
 353 // and calls the provided function f for each event.
 354 template <typename Func>
 355 void TraceReplay(Trace *trace, TracePart *last, Event *last_pos, Sid sid,
 356                  Epoch epoch, Func f) {
 357   TracePart *part = trace->parts.Front();
 358   Sid ev_sid = kFreeSid;
 359   Epoch ev_epoch = kEpochOver;
 360   for (;;) {
 361     DCHECK_EQ(part->trace, trace);
 362     // Note: an event can't start in the last element.
 363     // Since an event can take up to 2 elements,
 364     // we ensure we have at least 2 before adding an event.
 365     Event *end = &part->events[TracePart::kSize - 1];
 366     if (part == last)
 367       end = last_pos;
 368     f(kFreeSid, kEpochOver, nullptr);  // notify about part start
 369     for (Event *evp = &part->events[0]; evp < end; evp++) {
 370       Event *evp0 = evp;
 371       if (!evp->is_access && !evp->is_func) {
 372         switch (evp->type) {
 373           case EventType::kTime: {
 374             auto *ev = reinterpret_cast<EventTime *>(evp);
 375             ev_sid = static_cast<Sid>(ev->sid);
 376             ev_epoch = static_cast<Epoch>(ev->epoch);
 377             if (ev_sid == sid && ev_epoch > epoch)
 378               return;
 379             break;
 380           }
 381           case EventType::kAccessExt:
 382             FALLTHROUGH;
 383           case EventType::kAccessRange:
 384             FALLTHROUGH;
 385           case EventType::kLock:
 386             FALLTHROUGH;
 387           case EventType::kRLock:
 388             // These take 2 Event elements.
 389             evp++;
 390             break;
 391           case EventType::kUnlock:
 392             // This takes 1 Event element.
 393             break;
 394         }
 395       }
 396       CHECK_NE(ev_sid, kFreeSid);
 397       CHECK_NE(ev_epoch, kEpochOver);
 398       f(ev_sid, ev_epoch, evp0);
 399     }
 400     if (part == last)
 401       return;
 402     part = trace->parts.Next(part);
 403     CHECK(part);
 404   }
 405   CHECK(0);
 406 }
 407
 408 static void RestoreStackMatch(VarSizeStackTrace *pstk, MutexSet *pmset,
 409                               Vector<uptr> *stack, MutexSet *mset, uptr pc,
 410                               bool *found) {
 411   DPrintf2("    MATCHED\n");
 412   *pmset = *mset;
 413   stack->PushBack(pc);
 414   pstk->Init(&(*stack)[0], stack->Size());
 415   stack->PopBack();
 416   *found = true;
 417 }
 418
 419 // Checks if addr1|size1 is fully contained in addr2|size2.
 420 // We check for fully contained instread of just overlapping
 421 // because a memory access is always traced once, but can be
 422 // split into multiple accesses in the shadow.
 423 static constexpr bool IsWithinAccess(uptr addr1, uptr size1, uptr addr2,
 424                                      uptr size2) {
 425   return addr1 >= addr2 && addr1 + size1 <= addr2 + size2;
 426 }
 427
 428 // Replays the trace of slot sid up to the target event identified
 429 // by epoch/addr/size/typ and restores and returns tid, stack, mutex set
 430 // and tag for that event. If there are multiple such events, it returns
 431 // the last one. Returns false if the event is not present in the trace.
 432 bool RestoreStack(EventType type, Sid sid, Epoch epoch, uptr addr, uptr size,
 433                   AccessType typ, Tid *ptid, VarSizeStackTrace *pstk,
 434                   MutexSet *pmset, uptr *ptag) {
 435   // This function restores stack trace and mutex set for the thread/epoch.
 436   // It does so by getting stack trace and mutex set at the beginning of
 437   // trace part, and then replaying the trace till the given epoch.
 438   DPrintf2("RestoreStack: sid=%u@%u addr=0x%zx/%zu typ=%x\n",
 439            static_cast<int>(sid), static_cast<int>(epoch), addr, size,
 440            static_cast<int>(typ));
 441   ctx->slot_mtx.CheckLocked();  // needed to prevent trace part recycling
 442   ctx->thread_registry.CheckLocked();
 443   TidSlot *slot = &ctx->slots[static_cast<uptr>(sid)];
 444   Tid tid = kInvalidTid;
 445   // Need to lock the slot mutex as it protects slot->journal.
 446   slot->mtx.CheckLocked();
 447   for (uptr i = 0; i < slot->journal.Size(); i++) {
 448     DPrintf2("  journal: epoch=%d tid=%d\n",
 449              static_cast<int>(slot->journal[i].epoch), slot->journal[i].tid);
 450     if (i == slot->journal.Size() - 1 || slot->journal[i + 1].epoch > epoch) {
 451       tid = slot->journal[i].tid;
 452       break;
 453     }
 454   }
 455   if (tid == kInvalidTid)
 456     return false;
 457   *ptid = tid;
 458   ThreadContext *tctx =
 459       static_cast<ThreadContext *>(ctx->thread_registry.GetThreadLocked(tid));
 460   Trace *trace = &tctx->trace;
 461   // Snapshot first/last parts and the current position in the last part.
 462   TracePart *first_part;
 463   TracePart *last_part;
 464   Event *last_pos;
 465   {
 466     Lock lock(&trace->mtx);
 467     first_part = trace->parts.Front();
 468     if (!first_part) {
 469       DPrintf2("RestoreStack: tid=%d trace=%p no trace parts\n", tid, trace);
 470       return false;
 471     }
 472     last_part = trace->parts.Back();
 473     last_pos = trace->final_pos;
 474     if (tctx->thr)
 475       last_pos = (Event *)atomic_load_relaxed(&tctx->thr->trace_pos);
 476   }
 477   DynamicMutexSet mset;
 478   Vector<uptr> stack;
 479   uptr prev_pc = 0;
 480   bool found = false;
 481   bool is_read = typ & kAccessRead;
 482   bool is_atomic = typ & kAccessAtomic;
 483   bool is_free = typ & kAccessFree;
 484   DPrintf2("RestoreStack: tid=%d parts=[%p-%p] last_pos=%p\n", tid,
 485            trace->parts.Front(), last_part, last_pos);
 486   TraceReplay(
 487       trace, last_part, last_pos, sid, epoch,
 488       [&](Sid ev_sid, Epoch ev_epoch, Event *evp) {
 489         if (evp == nullptr) {
 490           // Each trace part is self-consistent, so we reset state.
 491           stack.Resize(0);
 492           mset->Reset();
 493           prev_pc = 0;
 494           return;
 495         }
 496         bool match = ev_sid == sid && ev_epoch == epoch;
 497         if (evp->is_access) {
 498           if (evp->is_func == 0 && evp->type == EventType::kAccessExt &&
 499               evp->_ == 0)  // NopEvent
 500             return;
 501           auto *ev = reinterpret_cast<EventAccess *>(evp);
 502           uptr ev_addr = RestoreAddr(ev->addr);
 503           uptr ev_size = 1 << ev->size_log;
 504           uptr ev_pc =
 505               prev_pc + ev->pc_delta - (1 << (EventAccess::kPCBits - 1));
 506           prev_pc = ev_pc;
 507           DPrintf2("  Access: pc=0x%zx addr=0x%zx/%zu type=%u/%u\n", ev_pc,
 508                    ev_addr, ev_size, ev->is_read, ev->is_atomic);
 509           if (match && type == EventType::kAccessExt &&
 510               IsWithinAccess(addr, size, ev_addr, ev_size) &&
 511               is_read == ev->is_read && is_atomic == ev->is_atomic && !is_free)
 512             RestoreStackMatch(pstk, pmset, &stack, mset, ev_pc, &found);
 513           return;
 514         }
 515         if (evp->is_func) {
 516           auto *ev = reinterpret_cast<EventFunc *>(evp);
 517           if (ev->pc) {
 518             DPrintf2(" FuncEnter: pc=0x%llx\n", ev->pc);
 519             stack.PushBack(ev->pc);
 520           } else {
 521             DPrintf2(" FuncExit\n");
 522             // We don't log pathologically large stacks in each part,
 523             // if the stack was truncated we can have more func exits than
 524             // entries.
 525             if (stack.Size())
 526               stack.PopBack();
 527           }
 528           return;
 529         }
 530         switch (evp->type) {
 531           case EventType::kAccessExt: {
 532             auto *ev = reinterpret_cast<EventAccessExt *>(evp);
 533             uptr ev_addr = RestoreAddr(ev->addr);
 534             uptr ev_size = 1 << ev->size_log;
 535             prev_pc = ev->pc;
 536             DPrintf2("  AccessExt: pc=0x%llx addr=0x%zx/%zu type=%u/%u\n",
 537                      ev->pc, ev_addr, ev_size, ev->is_read, ev->is_atomic);
 538             if (match && type == EventType::kAccessExt &&
 539                 IsWithinAccess(addr, size, ev_addr, ev_size) &&
 540                 is_read == ev->is_read && is_atomic == ev->is_atomic &&
 541                 !is_free)
 542               RestoreStackMatch(pstk, pmset, &stack, mset, ev->pc, &found);
 543             break;
 544           }
 545           case EventType::kAccessRange: {
 546             auto *ev = reinterpret_cast<EventAccessRange *>(evp);
 547             uptr ev_addr = RestoreAddr(ev->addr);
 548             uptr ev_size =
 549                 (ev->size_hi << EventAccessRange::kSizeLoBits) + ev->size_lo;
 550             uptr ev_pc = RestoreAddr(ev->pc);
 551             prev_pc = ev_pc;
 552             DPrintf2("  Range: pc=0x%zx addr=0x%zx/%zu type=%u/%u\n", ev_pc,
 553                      ev_addr, ev_size, ev->is_read, ev->is_free);
 554             if (match && type == EventType::kAccessExt &&
 555                 IsWithinAccess(addr, size, ev_addr, ev_size) &&
 556                 is_read == ev->is_read && !is_atomic && is_free == ev->is_free)
 557               RestoreStackMatch(pstk, pmset, &stack, mset, ev_pc, &found);
 558             break;
 559           }
 560           case EventType::kLock:
 561             FALLTHROUGH;
 562           case EventType::kRLock: {
 563             auto *ev = reinterpret_cast<EventLock *>(evp);
 564             bool is_write = ev->type == EventType::kLock;
 565             uptr ev_addr = RestoreAddr(ev->addr);
 566             uptr ev_pc = RestoreAddr(ev->pc);
 567             StackID stack_id =
 568                 (ev->stack_hi << EventLock::kStackIDLoBits) + ev->stack_lo;
 569             DPrintf2("  Lock: pc=0x%zx addr=0x%zx stack=%u write=%d\n", ev_pc,
 570                      ev_addr, stack_id, is_write);
 571             mset->AddAddr(ev_addr, stack_id, is_write);
 572             // Events with ev_pc == 0 are written to the beginning of trace
 573             // part as initial mutex set (are not real).
 574             if (match && type == EventType::kLock && addr == ev_addr && ev_pc)
 575               RestoreStackMatch(pstk, pmset, &stack, mset, ev_pc, &found);
 576             break;
 577           }
 578           case EventType::kUnlock: {
 579             auto *ev = reinterpret_cast<EventUnlock *>(evp);
 580             uptr ev_addr = RestoreAddr(ev->addr);
 581             DPrintf2("  Unlock: addr=0x%zx\n", ev_addr);
 582             mset->DelAddr(ev_addr);
 583             break;
 584           }
 585           case EventType::kTime:
 586             // TraceReplay already extracted sid/epoch from it,
 587             // nothing else to do here.
 588             break;
 589         }
 590       });
 591   ExtractTagFromStack(pstk, ptag);
 592   return found;
 593 }
 594
 595 bool RacyStacks::operator==(const RacyStacks &other) const {
 596   if (hash[0] == other.hash[0] && hash[1] == other.hash[1])
 597     return true;
 598   if (hash[0] == other.hash[1] && hash[1] == other.hash[0])
 599     return true;
 600   return false;
 601 }
 602
 603 static bool FindRacyStacks(const RacyStacks &hash) {
 604   for (uptr i = 0; i < ctx->racy_stacks.Size(); i++) {
 605     if (hash == ctx->racy_stacks[i]) {
 606       VPrintf(2, "ThreadSanitizer: suppressing report as doubled (stack)\n");
 607       return true;
 608     }
 609   }
 610   return false;
 611 }
 612
 613 static bool HandleRacyStacks(ThreadState *thr, VarSizeStackTrace traces[2]) {
 614   if (!flags()->suppress_equal_stacks)
 615     return false;
 616   RacyStacks hash;
 617   hash.hash[0] = md5_hash(traces[0].trace, traces[0].size * sizeof(uptr));
 618   hash.hash[1] = md5_hash(traces[1].trace, traces[1].size * sizeof(uptr));
 619   {
 620     ReadLock lock(&ctx->racy_mtx);
 621     if (FindRacyStacks(hash))
 622       return true;
 623   }
 624   Lock lock(&ctx->racy_mtx);
 625   if (FindRacyStacks(hash))
 626     return true;
 627   ctx->racy_stacks.PushBack(hash);
 628   return false;
 629 }
 630
 631 bool OutputReport(ThreadState *thr, const ScopedReport &srep) {
 632   // These should have been checked in ShouldReport.
 633   // It's too late to check them here, we have already taken locks.
 634   CHECK(flags()->report_bugs);
 635   CHECK(!thr->suppress_reports);
 636   atomic_store_relaxed(&ctx->last_symbolize_time_ns, NanoTime());
 637   const ReportDesc *rep = srep.GetReport();
 638   CHECK_EQ(thr->current_report, nullptr);
 639   thr->current_report = rep;
 640   Suppression *supp = 0;
 641   uptr pc_or_addr = 0;
 642   for (uptr i = 0; pc_or_addr == 0 && i < rep->mops.Size(); i++)
 643     pc_or_addr = IsSuppressed(rep->typ, rep->mops[i]->stack, &supp);
 644   for (uptr i = 0; pc_or_addr == 0 && i < rep->stacks.Size(); i++)
 645     pc_or_addr = IsSuppressed(rep->typ, rep->stacks[i], &supp);
 646   for (uptr i = 0; pc_or_addr == 0 && i < rep->threads.Size(); i++)
 647     pc_or_addr = IsSuppressed(rep->typ, rep->threads[i]->stack, &supp);
 648   for (uptr i = 0; pc_or_addr == 0 && i < rep->locs.Size(); i++)
 649     pc_or_addr = IsSuppressed(rep->typ, rep->locs[i], &supp);
 650   if (pc_or_addr != 0) {
 651     Lock lock(&ctx->fired_suppressions_mtx);
 652     FiredSuppression s = {srep.GetReport()->typ, pc_or_addr, supp};
 653     ctx->fired_suppressions.push_back(s);
 654   }
 655   {
 656     bool suppressed = OnReport(rep, pc_or_addr != 0);
 657     if (suppressed) {
 658       thr->current_report = nullptr;
 659       return false;
 660     }
 661   }
 662   PrintReport(rep);
 663   __tsan_on_report(rep);
 664   ctx->nreported++;
 665   if (flags()->halt_on_error)
 666     Die();
 667   thr->current_report = nullptr;
 668   return true;
 669 }
 670
 671 bool IsFiredSuppression(Context *ctx, ReportType type, StackTrace trace) {
 672   ReadLock lock(&ctx->fired_suppressions_mtx);
 673   for (uptr k = 0; k < ctx->fired_suppressions.size(); k++) {
 674     if (ctx->fired_suppressions[k].type != type)
 675       continue;
 676     for (uptr j = 0; j < trace.size; j++) {
 677       FiredSuppression *s = &ctx->fired_suppressions[k];
 678       if (trace.trace[j] == s->pc_or_addr) {
 679         if (s->supp)
 680           atomic_fetch_add(&s->supp->hit_count, 1, memory_order_relaxed);
 681         return true;
 682       }
 683     }
 684   }
 685   return false;
 686 }
 687
 688 static bool IsFiredSuppression(Context *ctx, ReportType type, uptr addr) {
 689   ReadLock lock(&ctx->fired_suppressions_mtx);
 690   for (uptr k = 0; k < ctx->fired_suppressions.size(); k++) {
 691     if (ctx->fired_suppressions[k].type != type)
 692       continue;
 693     FiredSuppression *s = &ctx->fired_suppressions[k];
 694     if (addr == s->pc_or_addr) {
 695       if (s->supp)
 696         atomic_fetch_add(&s->supp->hit_count, 1, memory_order_relaxed);
 697       return true;
 698     }
 699   }
 700   return false;
 701 }
 702
 703 static bool SpuriousRace(Shadow old) {
 704   Shadow last(LoadShadow(&ctx->last_spurious_race));
 705   return last.sid() == old.sid() && last.epoch() == old.epoch();
 706 }
 707
 708 void ReportRace(ThreadState *thr, RawShadow *shadow_mem, Shadow cur, Shadow old,
 709                 AccessType typ0) {
 710   CheckedMutex::CheckNoLocks();
 711
 712   // Symbolizer makes lots of intercepted calls. If we try to process them,
 713   // at best it will cause deadlocks on internal mutexes.
 714   ScopedIgnoreInterceptors ignore;
 715
 716   uptr addr = ShadowToMem(shadow_mem);
 717   DPrintf("#%d: ReportRace %p\n", thr->tid, (void *)addr);
 718   if (!ShouldReport(thr, ReportTypeRace))
 719     return;
 720   uptr addr_off0, size0;
 721   cur.GetAccess(&addr_off0, &size0, nullptr);
 722   uptr addr_off1, size1, typ1;
 723   old.GetAccess(&addr_off1, &size1, &typ1);
 724   if (!flags()->report_atomic_races &&
 725       ((typ0 & kAccessAtomic) || (typ1 & kAccessAtomic)) &&
 726       !(typ0 & kAccessFree) && !(typ1 & kAccessFree))
 727     return;
 728   if (SpuriousRace(old))
 729     return;
 730
 731   const uptr kMop = 2;
 732   Shadow s[kMop] = {cur, old};
 733   uptr addr0 = addr + addr_off0;
 734   uptr addr1 = addr + addr_off1;
 735   uptr end0 = addr0 + size0;
 736   uptr end1 = addr1 + size1;
 737   uptr addr_min = min(addr0, addr1);
 738   uptr addr_max = max(end0, end1);
 739   if (IsExpectedReport(addr_min, addr_max - addr_min))
 740     return;
 741
 742   ReportType rep_typ = ReportTypeRace;
 743   if ((typ0 & kAccessVptr) && (typ1 & kAccessFree))
 744     rep_typ = ReportTypeVptrUseAfterFree;
 745   else if (typ0 & kAccessVptr)
 746     rep_typ = ReportTypeVptrRace;
 747   else if (typ1 & kAccessFree)
 748     rep_typ = ReportTypeUseAfterFree;
 749
 750   if (IsFiredSuppression(ctx, rep_typ, addr))
 751     return;
 752
 753   VarSizeStackTrace traces[kMop];
 754   Tid tids[kMop] = {thr->tid, kInvalidTid};
 755   uptr tags[kMop] = {kExternalTagNone, kExternalTagNone};
 756
 757   ObtainCurrentStack(thr, thr->trace_prev_pc, &traces[0], &tags[0]);
 758   if (IsFiredSuppression(ctx, rep_typ, traces[0]))
 759     return;
 760
 761   DynamicMutexSet mset1;
 762   MutexSet *mset[kMop] = {&thr->mset, mset1};
 763
 764   // We need to lock the slot during RestoreStack because it protects
 765   // the slot journal.
 766   Lock slot_lock(&ctx->slots[static_cast<uptr>(s[1].sid())].mtx);
 767   ThreadRegistryLock l0(&ctx->thread_registry);
 768   Lock slots_lock(&ctx->slot_mtx);
 769   if (SpuriousRace(old))
 770     return;
 771   if (!RestoreStack(EventType::kAccessExt, s[1].sid(), s[1].epoch(), addr1,
 772                     size1, typ1, &tids[1], &traces[1], mset[1], &tags[1])) {
 773     StoreShadow(&ctx->last_spurious_race, old.raw());
 774     return;
 775   }
 776
 777   if (IsFiredSuppression(ctx, rep_typ, traces[1]))
 778     return;
 779
 780   if (HandleRacyStacks(thr, traces))
 781     return;
 782
 783   // If any of the accesses has a tag, treat this as an "external" race.
 784   uptr tag = kExternalTagNone;
 785   for (uptr i = 0; i < kMop; i++) {
 786     if (tags[i] != kExternalTagNone) {
 787       rep_typ = ReportTypeExternalRace;
 788       tag = tags[i];
 789       break;
 790     }
 791   }
 792
 793   ScopedReport rep(rep_typ, tag);
 794   for (uptr i = 0; i < kMop; i++)
 795     rep.AddMemoryAccess(addr, tags[i], s[i], tids[i], traces[i], mset[i]);
 796
 797   for (uptr i = 0; i < kMop; i++) {
 798     ThreadContext *tctx = static_cast<ThreadContext *>(
 799         ctx->thread_registry.GetThreadLocked(tids[i]));
 800     rep.AddThread(tctx);
 801   }
 802
 803   rep.AddLocation(addr_min, addr_max - addr_min);
 804
 805   if (flags()->print_full_thread_history) {
 806     const ReportDesc *rep_desc = rep.GetReport();
 807     for (uptr i = 0; i < rep_desc->threads.Size(); i++) {
 808       Tid parent_tid = rep_desc->threads[i]->parent_tid;
 809       if (parent_tid == kMainTid || parent_tid == kInvalidTid)
 810         continue;
 811       ThreadContext *parent_tctx = static_cast<ThreadContext *>(
 812           ctx->thread_registry.GetThreadLocked(parent_tid));
 813       rep.AddThread(parent_tctx);
 814     }
 815   }
 816
 817 #if !SANITIZER_GO
 818   if (!((typ0 | typ1) & kAccessFree) &&
 819       s[1].epoch() <= thr->last_sleep_clock.Get(s[1].sid()))
 820     rep.AddSleep(thr->last_sleep_stack_id);
 821 #endif
 822   OutputReport(thr, rep);
 823 }
 824
 825 void PrintCurrentStack(ThreadState *thr, uptr pc) {
 826   VarSizeStackTrace trace;
 827   ObtainCurrentStack(thr, pc, &trace);
 828   PrintStack(SymbolizeStack(trace));
 829 }
 830
 831 // Always inlining PrintCurrentStackSlow, because LocatePcInTrace assumes
 832 // __sanitizer_print_stack_trace exists in the actual unwinded stack, but
 833 // tail-call to PrintCurrentStackSlow breaks this assumption because
 834 // __sanitizer_print_stack_trace disappears after tail-call.
 835 // However, this solution is not reliable enough, please see dvyukov's comment
 836 // http://reviews.llvm.org/D19148#406208
 837 // Also see PR27280 comment 2 and 3 for breaking examples and analysis.
 838 ALWAYS_INLINE USED void PrintCurrentStackSlow(uptr pc) {
 839 #if !SANITIZER_GO
 840   uptr bp = GET_CURRENT_FRAME();
 841   auto *ptrace = New<BufferedStackTrace>();
 842   ptrace->Unwind(pc, bp, nullptr, false);
 843
 844   for (uptr i = 0; i < ptrace->size / 2; i++) {
 845     uptr tmp = ptrace->trace_buffer[i];
 846     ptrace->trace_buffer[i] = ptrace->trace_buffer[ptrace->size - i - 1];
 847     ptrace->trace_buffer[ptrace->size - i - 1] = tmp;
 848   }
 849   PrintStack(SymbolizeStack(*ptrace));
 850 #endif
 851 }
 852
 853 }  // namespace __tsan
 854
 855 using namespace __tsan;
 856
 857 extern "C" {
 858 SANITIZER_INTERFACE_ATTRIBUTE
 859 void __sanitizer_print_stack_trace() {
 860   PrintCurrentStackSlow(StackTrace::GetCurrentPc());
 861 }
 862 }  // extern "C"