path: root/libsanitizer/tsan/tsan_rtl_thread.cpp

//===-- 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(), epoch0(), epoch1() {}

#if !SANITIZER_GO
ThreadContext::~ThreadContext() {
}
#endif

void ThreadContext::OnReset() {
  CHECK_EQ(sync.size(), 0);
  uptr trace_p = GetThreadTrace(tid);
  ReleaseMemoryPagesToOS(trace_p, trace_p + TraceSize() * sizeof(Event));
  //!!! ReleaseMemoryToOS(GetThreadTraceHeader(tid), sizeof(Trace));
}

#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

#if !SANITIZER_GO
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 {
  ThreadState *thr;
  uptr pc;
};

Tid ThreadCreate(ThreadState *thr, uptr pc, uptr uid, bool detached) {
  OnCreatedArgs args = { thr, pc };
  u32 parent_tid = thr ? thr->tid : kInvalidTid;  // No parent for GCD workers.
  Tid tid = ctx->thread_registry.CreateThread(uid, detached, parent_tid, &args);
  DPrintf("#%d: ThreadCreate tid=%d uid=%zu\n", parent_tid, tid, uid);
  return tid;
}

void ThreadContext::OnCreated(void *arg) {
  thr = 0;
  if (tid == kMainTid)
    return;
  OnCreatedArgs *args = static_cast<OnCreatedArgs *>(arg);
  if (!args->thr)  // GCD workers don't have a parent thread.
    return;
  args->thr->fast_state.IncrementEpoch();
  // Can't increment epoch w/o writing to the trace as well.
  TraceAddEvent(args->thr, args->thr->fast_state, EventTypeMop, 0);
  ReleaseImpl(args->thr, 0, &sync);
  creation_stack_id = CurrentStackId(args->thr, args->pc);
}

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) {
  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

  ThreadRegistry *tr = &ctx->thread_registry;
  OnStartedArgs args = { thr, stk_addr, stk_size, tls_addr, tls_size };
  tr->StartThread(tid, os_id, thread_type, &args);

  while (!thr->tctx->trace.parts.Empty()) thr->tctx->trace.parts.PopBack();

#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) {
  OnStartedArgs *args = static_cast<OnStartedArgs *>(arg);
  thr = args->thr;
  // RoundUp so that one trace part does not contain events
  // from different threads.
  epoch0 = RoundUp(epoch1 + 1, kTracePartSize);
  epoch1 = (u64)-1;
  new (thr)
      ThreadState(ctx, tid, unique_id, epoch0, reuse_count, args->stk_addr,
                  args->stk_size, args->tls_addr, args->tls_size);
  if (common_flags()->detect_deadlocks)
    thr->dd_lt = ctx->dd->CreateLogicalThread(unique_id);
  thr->fast_state.SetHistorySize(flags()->history_size);
  // Commit switch to the new part of the trace.
  // TraceAddEvent will reset stack0/mset0 in the new part for us.
  TraceAddEvent(thr, thr->fast_state, EventTypeMop, 0);

  thr->fast_synch_epoch = epoch0;
  AcquireImpl(thr, 0, &sync);
  sync.Reset(&thr->proc()->clock_cache);
  thr->tctx = this;
  thr->is_inited = true;
  DPrintf(
      "#%d: ThreadStart epoch=%zu stk_addr=%zx stk_size=%zx "
      "tls_addr=%zx tls_size=%zx\n",
      tid, (uptr)epoch0, args->stk_addr, args->stk_size, args->tls_addr,
      args->tls_size);
}

void ThreadFinish(ThreadState *thr) {
  ThreadCheckIgnore(thr);
  if (thr->stk_addr && thr->stk_size)
    DontNeedShadowFor(thr->stk_addr, thr->stk_size);
  if (thr->tls_addr && thr->tls_size)
    DontNeedShadowFor(thr->tls_addr, thr->tls_size);
  thr->is_dead = true;
  ctx->thread_registry.FinishThread(thr->tid);
}

void ThreadContext::OnFinished() {
#if SANITIZER_GO
  Free(thr->shadow_stack);
  thr->shadow_stack_pos = nullptr;
  thr->shadow_stack_end = nullptr;
#endif
  if (!detached) {
    thr->fast_state.IncrementEpoch();
    // Can't increment epoch w/o writing to the trace as well.
    TraceAddEvent(thr, thr->fast_state, EventTypeMop, 0);
    ReleaseImpl(thr, 0, &sync);
  }
  epoch1 = thr->fast_state.epoch();

  if (common_flags()->detect_deadlocks)
    ctx->dd->DestroyLogicalThread(thr->dd_lt);
  thr->clock.ResetCached(&thr->proc()->clock_cache);
#if !SANITIZER_GO
  thr->last_sleep_clock.ResetCached(&thr->proc()->clock_cache);
#endif
#if !SANITIZER_GO
  PlatformCleanUpThreadState(thr);
#endif
  thr->~ThreadState();
  thr = 0;
}

struct ConsumeThreadContext {
  uptr uid;
  ThreadContextBase *tctx;
};

static bool ConsumeThreadByUid(ThreadContextBase *tctx, void *arg) {
  ConsumeThreadContext *findCtx = (ConsumeThreadContext *)arg;
  if (tctx->user_id == findCtx->uid && tctx->status != ThreadStatusInvalid) {
    if (findCtx->tctx) {
      // Ensure that user_id is unique. If it's not the case we are screwed.
      // Something went wrong before, but now there is no way to recover.
      // Returning a wrong thread is not an option, it may lead to very hard
      // to debug false positives (e.g. if we join a wrong thread).
      Report("ThreadSanitizer: dup thread with used id 0x%zx\n", findCtx->uid);
      Die();
    }
    findCtx->tctx = tctx;
    tctx->user_id = 0;
  }
  return false;
}

Tid ThreadConsumeTid(ThreadState *thr, uptr pc, uptr uid) {
  ConsumeThreadContext findCtx = {uid, nullptr};
  ctx->thread_registry.FindThread(ConsumeThreadByUid, &findCtx);
  Tid tid = findCtx.tctx ? findCtx.tctx->tid : kInvalidTid;
  DPrintf("#%d: ThreadTid uid=%zu tid=%d\n", thr->tid, uid, tid);
  return tid;
}

void ThreadJoin(ThreadState *thr, uptr pc, Tid tid) {
  CHECK_GT(tid, 0);
  CHECK_LT(tid, kMaxTid);
  DPrintf("#%d: ThreadJoin tid=%d\n", thr->tid, tid);
  ctx->thread_registry.JoinThread(tid, thr);
}

void ThreadContext::OnJoined(void *arg) {
  ThreadState *caller_thr = static_cast<ThreadState *>(arg);
  AcquireImpl(caller_thr, 0, &sync);
  sync.Reset(&caller_thr->proc()->clock_cache);
}

void ThreadContext::OnDead() { CHECK_EQ(sync.size(), 0); }

void ThreadDetach(ThreadState *thr, uptr pc, Tid tid) {
  CHECK_GT(tid, 0);
  CHECK_LT(tid, kMaxTid);
  ctx->thread_registry.DetachThread(tid, thr);
}

void ThreadContext::OnDetached(void *arg) {
  ThreadState *thr1 = static_cast<ThreadState *>(arg);
  sync.Reset(&thr1->proc()->clock_cache);
}

void ThreadNotJoined(ThreadState *thr, uptr pc, Tid tid, uptr uid) {
  CHECK_GT(tid, 0);
  CHECK_LT(tid, kMaxTid);
  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