[Tsan] Do not sanitize memcpy() during thread initialization on FreeBSD

[dvyukov]

lib/tsan/rtl/tsan_interceptors.cc

673

please add is_inited flag to ThreadState, similar to is_dead
and set it in ThreadContext::OnStarted
shadow_stack_pos check looks confusing

[kutuzov.viktor.84]

Updated.

[dvyukov]

LGTM

lib/tsan/rtl/tsan_interceptors.cc

if (buf->sp <= sp) {
       thr->jmp_bufs[i] = thr->jmp_bufs[sz - 1];
       thr->jmp_bufs.PopBack();
       i--;
     }
   }
 }
 
 static void SetJmp(ThreadState *thr, uptr sp, uptr mangled_sp) {
-  if (thr->shadow_stack_pos == 0)  // called from libc guts during bootstrap
+  if (!thr->is_inited)  // called from libc guts during bootstrap
     return;
   // Cleanup old bufs.
   JmpBufGarbageCollect(thr, sp);
   // Remember the buf.
   JmpBuf *buf = thr->jmp_bufs.PushBack();
   buf->sp = sp;
   buf->mangled_sp = mangled_sp;
   buf->shadow_stack_pos = thr->shadow_stack_pos;

 
 TSAN_INTERCEPTOR(void*, memset, void *dst, int v, uptr size) {
   SCOPED_TSAN_INTERCEPTOR(memset, dst, v, size);
   MemoryAccessRange(thr, pc, (uptr)dst, size, true);
   return internal_memset(dst, v, size);
 }
 
 TSAN_INTERCEPTOR(void*, memcpy, void *dst, const void *src, uptr size) {
+  // On FreeBSD we get here from libthr internals on thread initialization.
+  if (cur_thread()->is_inited) {
     SCOPED_TSAN_INTERCEPTOR(memcpy, dst, src, size);
     MemoryAccessRange(thr, pc, (uptr)dst, size, true);
     MemoryAccessRange(thr, pc, (uptr)src, size, false);
+  }
   return internal_memcpy(dst, src, size);
 }
 
 TSAN_INTERCEPTOR(int, memcmp, const void *s1, const void *s2, uptr n) {
   SCOPED_TSAN_INTERCEPTOR(memcmp, s1, s2, n);
   int res = 0;
   uptr len = 0;
   for (; len < n; len++) {

lib/tsan/rtl/tsan_rtl.h

 #endif
 #if TSAN_COLLECT_STATS
   u64 stat[StatCnt];
 #endif
   const int tid;
   const int unique_id;
   bool in_symbolizer;
   bool in_ignored_lib;
+  bool is_inited;
   bool is_dead;
   bool is_freeing;
   bool is_vptr_access;
   const uptr stk_addr;
   const uptr stk_size;
   const uptr tls_addr;
   const uptr tls_size;
   ThreadContext *tctx;

lib/tsan/rtl/tsan_rtl.cc

void GrowShadowStack(ThreadState *thr) {
   internal_free(thr->shadow_stack);
   thr->shadow_stack = newstack;
   thr->shadow_stack_pos = newstack + sz;
   thr->shadow_stack_end = newstack + newsz;
 }
 #endif
 
 u32 CurrentStackId(ThreadState *thr, uptr pc) {
-  if (thr->shadow_stack_pos == 0)  // May happen during bootstrap.
+  if (!thr->is_inited)  // May happen during bootstrap.
     return 0;
   if (pc != 0) {
 #ifndef SANITIZER_GO
     DCHECK_LT(thr->shadow_stack_pos, thr->shadow_stack_end);
 #else
     if (thr->shadow_stack_pos == thr->shadow_stack_end)
       GrowShadowStack(thr);
 #endif

lib/tsan/rtl/tsan_rtl_thread.cc

#endif
   // 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);
   StatInc(thr, StatSyncAcquire);
   sync.Reset(&thr->clock_cache);
+  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 ThreadContext::OnFinished() {
   if (!detached) {