text: //===-- tsan_rtl_thread.cpp -----------------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // This file is a part of ThreadSanitizer (TSan), a race detector.
  //
  //===----------------------------------------------------------------------===//
  
  #include "sanitizer_common/sanitizer_placement_new.h"
  #include "tsan_rtl.h"
  #include "tsan_mman.h"
  #include "tsan_platform.h"
  #include "tsan_report.h"
  #include "tsan_sync.h"
  
  namespace __tsan {
  
  // ThreadContext implementation.
  
  ThreadContext::ThreadContext(Tid tid) : ThreadContextBase(tid), thr(), sync() {}
  
  #if !SANITIZER_GO
  ThreadContext::~ThreadContext() {
  }
  #endif
  
  void ThreadContext::OnReset() { CHECK(!sync); }
  
  #if !SANITIZER_GO
  struct ThreadLeak {
    ThreadContext *tctx;
    int count;
  };
  
  static void CollectThreadLeaks(ThreadContextBase *tctx_base, void *arg) {
    auto &leaks = *static_cast<Vector<ThreadLeak> *>(arg);
    auto *tctx = static_cast<ThreadContext *>(tctx_base);
    if (tctx->detached || tctx->status != ThreadStatusFinished)
      return;
    for (uptr i = 0; i < leaks.Size(); i++) {
      if (leaks[i].tctx->creation_stack_id == tctx->creation_stack_id) {
        leaks[i].count++;
        return;
      }
    }
    leaks.PushBack({tctx, 1});
  }
  #endif
  
  // Disabled on Mac because lldb test TestTsanBasic fails:
  // https://reviews.llvm.org/D112603#3163158
  #if !SANITIZER_GO && !SANITIZER_MAC
  static void ReportIgnoresEnabled(ThreadContext *tctx, IgnoreSet *set) {
    if (tctx->tid == kMainTid) {
      Printf("ThreadSanitizer: main thread finished with ignores enabled\n");
    } else {
      Printf("ThreadSanitizer: thread T%d %s finished with ignores enabled,"
        " created at:\n", tctx->tid, tctx->name);
      PrintStack(SymbolizeStackId(tctx->creation_stack_id));
    }
    Printf("  One of the following ignores was not ended"
        " (in order of probability)\n");
    for (uptr i = 0; i < set->Size(); i++) {
      Printf("  Ignore was enabled at:\n");
      PrintStack(SymbolizeStackId(set->At(i)));
    }
    Die();
  }
  
  static void ThreadCheckIgnore(ThreadState *thr) {
    if (ctx->after_multithreaded_fork)
      return;
    if (thr->ignore_reads_and_writes)
      ReportIgnoresEnabled(thr->tctx, &thr->mop_ignore_set);
    if (thr->ignore_sync)
      ReportIgnoresEnabled(thr->tctx, &thr->sync_ignore_set);
  }
  #else
  static void ThreadCheckIgnore(ThreadState *thr) {}
  #endif
  
  void ThreadFinalize(ThreadState *thr) {
    ThreadCheckIgnore(thr);
  #if !SANITIZER_GO
    if (!ShouldReport(thr, ReportTypeThreadLeak))
      return;
    ThreadRegistryLock l(&ctx->thread_registry);
    Vector<ThreadLeak> leaks;
    ctx->thread_registry.RunCallbackForEachThreadLocked(CollectThreadLeaks,
                                                        &leaks);
    for (uptr i = 0; i < leaks.Size(); i++) {
      ScopedReport rep(ReportTypeThreadLeak);
      rep.AddThread(leaks[i].tctx, true);
      rep.SetCount(leaks[i].count);
      OutputReport(thr, rep);
    }
  #endif
  }
  
  int ThreadCount(ThreadState *thr) {
    uptr result;
    ctx->thread_registry.GetNumberOfThreads(0, 0, &result);
    return (int)result;
  }
  
  struct OnCreatedArgs {
    VectorClock *sync;
    uptr sync_epoch;
    StackID stack;
  };
  
  Tid ThreadCreate(ThreadState *thr, uptr pc, uptr uid, bool detached) {
    // The main thread and GCD workers don't have a parent thread.
    Tid parent = kInvalidTid;
    OnCreatedArgs arg = {nullptr, 0, kInvalidStackID};
    if (thr) {
      parent = thr->tid;
      arg.stack = CurrentStackId(thr, pc);
      if (!thr->ignore_sync) {
        SlotLocker locker(thr);
        thr->clock.ReleaseStore(&arg.sync);
        arg.sync_epoch = ctx->global_epoch;
        IncrementEpoch(thr);
      }
    }
    Tid tid = ctx->thread_registry.CreateThread(uid, detached, parent, &arg);
    DPrintf("#%d: ThreadCreate tid=%d uid=%zu\n", parent, tid, uid);
    return tid;
  }
  
  void ThreadContext::OnCreated(void *arg) {
    OnCreatedArgs *args = static_cast<OnCreatedArgs *>(arg);
    sync = args->sync;
    sync_epoch = args->sync_epoch;
    creation_stack_id = args->stack;
  }
  
  extern "C" void __tsan_stack_initialization() {}
  
  struct OnStartedArgs {
    ThreadState *thr;
    uptr stk_addr;
    uptr stk_size;
    uptr tls_addr;
    uptr tls_size;
  };
  
  void ThreadStart(ThreadState *thr, Tid tid, tid_t os_id,
                   ThreadType thread_type) {
    ctx->thread_registry.StartThread(tid, os_id, thread_type, thr);
    if (!thr->ignore_sync) {
      SlotAttachAndLock(thr);
      if (thr->tctx->sync_epoch == ctx->global_epoch)
        thr->clock.Acquire(thr->tctx->sync);
      SlotUnlock(thr);
    }
    Free(thr->tctx->sync);
  
    uptr stk_addr = 0;
    uptr stk_size = 0;
    uptr tls_addr = 0;
    uptr tls_size = 0;
  #if !SANITIZER_GO
    if (thread_type != ThreadType::Fiber)
      GetThreadStackAndTls(tid == kMainTid, &stk_addr, &stk_size, &tls_addr,
                           &tls_size);
  #endif
    thr->stk_addr = stk_addr;
    thr->stk_size = stk_size;
    thr->tls_addr = tls_addr;
    thr->tls_size = tls_size;
  
  #if !SANITIZER_GO
    if (ctx->after_multithreaded_fork) {
      thr->ignore_interceptors++;
      ThreadIgnoreBegin(thr, 0);
      ThreadIgnoreSyncBegin(thr, 0);
    }
  #endif
  
  #if !SANITIZER_GO
    // Don't imitate stack/TLS writes for the main thread,
    // because its initialization is synchronized with all
    // subsequent threads anyway.
    if (tid != kMainTid) {
      if (stk_addr && stk_size) {
        const uptr pc = StackTrace::GetNextInstructionPc(
            reinterpret_cast<uptr>(__tsan_stack_initialization));
        MemoryRangeImitateWrite(thr, pc, stk_addr, stk_size);
      }
  
      if (tls_addr && tls_size)
        ImitateTlsWrite(thr, tls_addr, tls_size);
    }
  #endif
  }
  
  void ThreadContext::OnStarted(void *arg) {
    thr = static_cast<ThreadState *>(arg);
    DPrintf("#%d: ThreadStart\n", tid);
    new (thr) ThreadState(tid);
    if (common_flags()->detect_deadlocks)
      thr->dd_lt = ctx->dd->CreateLogicalThread(tid);
    thr->tctx = this;
  #if !SANITIZER_GO
    thr->is_inited = true;
  #endif
  }
  
  void ThreadFinish(ThreadState *thr) {
    DPrintf("#%d: ThreadFinish\n", thr->tid);
    ThreadCheckIgnore(thr);
    if (thr->stk_addr && thr->stk_size) {
      MemoryResetRange(thr, /*pc=*/ 1, thr->stk_addr, thr->stk_size);
      DontNeedShadowFor(thr->stk_addr, thr->stk_size);
    }
    if (thr->tls_addr && thr->tls_size) {
      MemoryResetRange(thr, /*pc=*/ 1, thr->tls_addr, thr->tls_size);
      DontNeedShadowFor(thr->tls_addr, thr->tls_size);
    }
    thr->is_dead = true;
  #if !SANITIZER_GO
    thr->is_inited = false;
    thr->ignore_interceptors++;
    PlatformCleanUpThreadState(thr);
  #endif
    if (!thr->ignore_sync) {
      SlotLocker locker(thr);
      ThreadRegistryLock lock(&ctx->thread_registry);
      // Note: detached is protected by the thread registry mutex,
      // the thread may be detaching concurrently in another thread.
      if (!thr->tctx->detached) {
        thr->clock.ReleaseStore(&thr->tctx->sync);
        thr->tctx->sync_epoch = ctx->global_epoch;
        IncrementEpoch(thr);
      }
    }
  #if !SANITIZER_GO
    UnmapOrDie(thr->shadow_stack, kShadowStackSize * sizeof(uptr));
  #else
    Free(thr->shadow_stack);
  #endif
    thr->shadow_stack = nullptr;
    thr->shadow_stack_pos = nullptr;
    thr->shadow_stack_end = nullptr;
    if (common_flags()->detect_deadlocks)
      ctx->dd->DestroyLogicalThread(thr->dd_lt);
    SlotDetach(thr);
    ctx->thread_registry.FinishThread(thr->tid);
    thr->~ThreadState();
  }
  
  void ThreadContext::OnFinished() {
    Lock lock(&ctx->slot_mtx);
    Lock lock1(&trace.mtx);
    // Queue all trace parts into the global recycle queue.
    auto parts = &trace.parts;
    while (trace.local_head) {
      CHECK(parts->Queued(trace.local_head));
      ctx->trace_part_recycle.PushBack(trace.local_head);
      trace.local_head = parts->Next(trace.local_head);
    }
    ctx->trace_part_recycle_finished += parts->Size();
    if (ctx->trace_part_recycle_finished > Trace::kFinishedThreadHi) {
      ctx->trace_part_finished_excess += parts->Size();
      trace.parts_allocated = 0;
    } else if (ctx->trace_part_recycle_finished > Trace::kFinishedThreadLo &&
               parts->Size() > 1) {
      ctx->trace_part_finished_excess += parts->Size() - 1;
      trace.parts_allocated = 1;
    }
    // From now on replay will use trace->final_pos.
    trace.final_pos = (Event *)atomic_load_relaxed(&thr->trace_pos);
    atomic_store_relaxed(&thr->trace_pos, 0);
    thr->tctx = nullptr;
    thr = nullptr;
  }
  
  struct ConsumeThreadContext {
    uptr uid;
    ThreadContextBase *tctx;
  };
  
  Tid ThreadConsumeTid(ThreadState *thr, uptr pc, uptr uid) {
    return ctx->thread_registry.ConsumeThreadUserId(uid);
  }
  
  struct JoinArg {
    VectorClock *sync;
    uptr sync_epoch;
  };
  
  void ThreadJoin(ThreadState *thr, uptr pc, Tid tid) {
    CHECK_GT(tid, 0);
    DPrintf("#%d: ThreadJoin tid=%d\n", thr->tid, tid);
    JoinArg arg = {};
    ctx->thread_registry.JoinThread(tid, &arg);
    if (!thr->ignore_sync) {
      SlotLocker locker(thr);
      if (arg.sync_epoch == ctx->global_epoch)
        thr->clock.Acquire(arg.sync);
    }
    Free(arg.sync);
  }
  
  void ThreadContext::OnJoined(void *ptr) {
    auto arg = static_cast<JoinArg *>(ptr);
    arg->sync = sync;
    arg->sync_epoch = sync_epoch;
    sync = nullptr;
    sync_epoch = 0;
  }
  
  void ThreadContext::OnDead() { CHECK_EQ(sync, nullptr); }
  
  void ThreadDetach(ThreadState *thr, uptr pc, Tid tid) {
    CHECK_GT(tid, 0);
    ctx->thread_registry.DetachThread(tid, thr);
  }
  
  void ThreadContext::OnDetached(void *arg) { Free(sync); }
  
  void ThreadNotJoined(ThreadState *thr, uptr pc, Tid tid, uptr uid) {
    CHECK_GT(tid, 0);
    ctx->thread_registry.SetThreadUserId(tid, uid);
  }
  
  void ThreadSetName(ThreadState *thr, const char *name) {
    ctx->thread_registry.SetThreadName(thr->tid, name);
  }
  
  #if !SANITIZER_GO
  void FiberSwitchImpl(ThreadState *from, ThreadState *to) {
    Processor *proc = from->proc();
    ProcUnwire(proc, from);
    ProcWire(proc, to);
    set_cur_thread(to);
  }
  
  ThreadState *FiberCreate(ThreadState *thr, uptr pc, unsigned flags) {
    void *mem = Alloc(sizeof(ThreadState));
    ThreadState *fiber = static_cast<ThreadState *>(mem);
    internal_memset(fiber, 0, sizeof(*fiber));
    Tid tid = ThreadCreate(thr, pc, 0, true);
    FiberSwitchImpl(thr, fiber);
    ThreadStart(fiber, tid, 0, ThreadType::Fiber);
    FiberSwitchImpl(fiber, thr);
    return fiber;
  }
  
  void FiberDestroy(ThreadState *thr, uptr pc, ThreadState *fiber) {
    FiberSwitchImpl(thr, fiber);
    ThreadFinish(fiber);
    FiberSwitchImpl(fiber, thr);
    Free(fiber);
  }
  
  void FiberSwitch(ThreadState *thr, uptr pc,
                   ThreadState *fiber, unsigned flags) {
    if (!(flags & FiberSwitchFlagNoSync))
      Release(thr, pc, (uptr)fiber);
    FiberSwitchImpl(thr, fiber);
    if (!(flags & FiberSwitchFlagNoSync))
      Acquire(fiber, pc, (uptr)fiber);
  }
  #endif
  
  }  // namespace __tsan
  