tsan: fix trace handling when trace is reused between threads

llvm-svn: 169259

Author: dvyukov

compiler-rt/lib/tsan/rtl/tsan_defs.h

@@ -128,11 +128,17 @@ T max(T a, T b) {
 }
 
 template<typename T>
-T RoundUp(T p, int align) {
+T RoundUp(T p, u64 align) {
   DCHECK_EQ(align & (align - 1), 0);
   return (T)(((u64)p + align - 1) & ~(align - 1));
 }
 
+template<typename T>
+T RoundDown(T p, u64 align) {
+  DCHECK_EQ(align & (align - 1), 0);
+  return (T)((u64)p & ~(align - 1));
+}
+
 struct MD5Hash {
   u64 hash[2];
   bool operator==(const MD5Hash &other) const;

compiler-rt/lib/tsan/rtl/tsan_rtl.cc

@@ -286,7 +286,7 @@ void TraceSwitch(ThreadState *thr) {
   thr->nomalloc++;
   ScopedInRtl in_rtl;
   Lock l(&thr->trace.mtx);
-  unsigned trace = (thr->fast_state.epoch() / kTracePartSize) % kTraceParts;
+  unsigned trace = (thr->fast_state.epoch() / kTracePartSize) % TraceParts();
   TraceHeader *hdr = &thr->trace.headers[trace];
   hdr->epoch0 = thr->fast_state.epoch();
   hdr->stack0.ObtainCurrent(thr, 0);
@@ -303,6 +303,10 @@ uptr TraceSize() {
   return (uptr)(1ull << (kTracePartSizeBits + flags()->history_size + 1));
 }
 
+uptr TraceParts() {
+  return TraceSize() / kTracePartSize;
+}
+
 #ifndef TSAN_GO
 extern "C" void __tsan_trace_switch() {
   TraceSwitch(cur_thread());

compiler-rt/lib/tsan/rtl/tsan_rtl.h

@@ -568,6 +568,7 @@ void AfterSleep(ThreadState *thr, uptr pc);
 void TraceSwitch(ThreadState *thr);
 uptr TraceTopPC(ThreadState *thr);
 uptr TraceSize();
+uptr TraceParts();
 
 extern "C" void __tsan_trace_switch();
 void ALWAYS_INLINE INLINE TraceAddEvent(ThreadState *thr, FastState fs,

compiler-rt/lib/tsan/rtl/tsan_rtl_report.cc

@@ -265,12 +265,12 @@ void RestoreStack(int tid, const u64 epoch, StackTrace *stk) {
     return;
   }
   Lock l(&trace->mtx);
-  const int partidx = (epoch / (TraceSize() / kTraceParts)) % kTraceParts;
+  const int partidx = (epoch / kTracePartSize) % TraceParts();
   TraceHeader* hdr = &trace->headers[partidx];
   if (epoch < hdr->epoch0)
     return;
   const u64 eend = epoch % TraceSize();
-  const u64 ebegin = eend / kTracePartSize * kTracePartSize;
+  const u64 ebegin = RoundDown(eend, kTracePartSize);
   DPrintf("#%d: RestoreStack epoch=%zu ebegin=%zu eend=%zu partidx=%d\n",
           tid, (uptr)epoch, (uptr)ebegin, (uptr)eend, partidx);
   InternalScopedBuffer<uptr> stack(1024);  // FIXME: de-hardcode 1024

compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cc

@@ -187,7 +187,9 @@ void ThreadStart(ThreadState *thr, int tid, uptr os_id) {
   CHECK_EQ(tctx->status, ThreadStatusCreated);
   tctx->status = ThreadStatusRunning;
   tctx->os_id = os_id;
-  tctx->epoch0 = tctx->epoch1 + 1;
+  // RoundUp so that one trace part does not contain events
+  // from different threads.
+  tctx->epoch0 = RoundUp(tctx->epoch1 + 1, kTracePartSize);
   tctx->epoch1 = (u64)-1;
   new(thr) ThreadState(CTX(), tid, tctx->unique_id,
       tctx->epoch0, stk_addr, stk_size,
@@ -205,6 +207,8 @@ void ThreadStart(ThreadState *thr, int tid, uptr os_id) {
   thr->clock.set(tid, tctx->epoch0);
   thr->clock.acquire(&tctx->sync);
   thr->fast_state.SetHistorySize(flags()->history_size);
+  const uptr trace = (tctx->epoch0 / kTracePartSize) % TraceParts();
+  thr->trace.headers[trace].epoch0 = tctx->epoch0;
   StatInc(thr, StatSyncAcquire);
   DPrintf("#%d: ThreadStart epoch=%zu stk_addr=%zx stk_size=%zx "
           "tls_addr=%zx tls_size=%zx\n",
@@ -250,7 +254,7 @@ void ThreadFinish(ThreadState *thr) {
   // Save from info about the thread.
   tctx->dead_info = new(internal_alloc(MBlockDeadInfo, sizeof(ThreadDeadInfo)))
       ThreadDeadInfo();
-  for (int i = 0; i < kTraceParts; i++) {
+  for (uptr i = 0; i < TraceParts(); i++) {
     tctx->dead_info->trace.headers[i].epoch0 = thr->trace.headers[i].epoch0;
     tctx->dead_info->trace.headers[i].stack0.CopyFrom(
         thr->trace.headers[i].stack0);