[compiler-rt] r301795 - tsan: support linker init flag in __tsan_mutex_destroy

[Dmitry Vyukov via llvm-commits]

Author: dvyukov
Date: Mon May  1 05:01:13 2017
New Revision: 301795

URL: http://llvm.org/viewvc/llvm-project?rev=301795&view=rev
Log:
tsan: support linker init flag in __tsan_mutex_destroy

For a linker init mutex with lazy flag setup
(no __tsan_mutex_create call), it is possible that
no lock/unlock happened before the destroy call.
Then when destroy runs we still don't know that
it is a linker init mutex and will emulate a memory write.
This in turn can lead to false positives as the mutex
is in fact linker initialized.

Support linker init flag in destroy annotation to resolve this.


Modified:
    compiler-rt/trunk/include/sanitizer/tsan_interface.h
    compiler-rt/trunk/lib/tsan/rtl/tsan_interface_ann.cc
    compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h
    compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_mutex.cc

Modified: compiler-rt/trunk/include/sanitizer/tsan_interface.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/include/sanitizer/tsan_interface.h?rev=301795&r1=301794&r2=301795&view=diff
==============================================================================
--- compiler-rt/trunk/include/sanitizer/tsan_interface.h (original)
+++ compiler-rt/trunk/include/sanitizer/tsan_interface.h Mon May  1 05:01:13 2017
@@ -68,7 +68,8 @@ const unsigned __tsan_mutex_recursive_un
 void __tsan_mutex_create(void *addr, unsigned flags);
 
 // Annotate destruction of a mutex.
-// Supported flags: none.
+// Supported flags:
+//   - __tsan_mutex_linker_init
 void __tsan_mutex_destroy(void *addr, unsigned flags);
 
 // Annotate start of lock operation.

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_interface_ann.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_interface_ann.cc?rev=301795&r1=301794&r2=301795&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_interface_ann.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_interface_ann.cc Mon May  1 05:01:13 2017
@@ -471,7 +471,7 @@ void __tsan_mutex_create(void *m, unsign
 INTERFACE_ATTRIBUTE
 void __tsan_mutex_destroy(void *m, unsigned flagz) {
   SCOPED_ANNOTATION(__tsan_mutex_destroy);
-  MutexDestroy(thr, pc, (uptr)m);
+  MutexDestroy(thr, pc, (uptr)m, flagz);
 }
 
 INTERFACE_ATTRIBUTE

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h?rev=301795&r1=301794&r2=301795&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h Mon May  1 05:01:13 2017
@@ -763,7 +763,7 @@ void ProcUnwire(Processor *proc, ThreadS
 // Note: the parameter is called flagz, because flags is already taken
 // by the global function that returns flags.
 void MutexCreate(ThreadState *thr, uptr pc, uptr addr, u32 flagz = 0);
-void MutexDestroy(ThreadState *thr, uptr pc, uptr addr);
+void MutexDestroy(ThreadState *thr, uptr pc, uptr addr, u32 flagz = 0);
 void MutexPreLock(ThreadState *thr, uptr pc, uptr addr, u32 flagz = 0);
 void MutexPostLock(ThreadState *thr, uptr pc, uptr addr, u32 flagz = 0,
     int rec = 1);

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_mutex.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_mutex.cc?rev=301795&r1=301794&r2=301795&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_mutex.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_mutex.cc Mon May  1 05:01:13 2017
@@ -78,13 +78,13 @@ void MutexCreate(ThreadState *thr, uptr
   s->mtx.Unlock();
 }
 
-void MutexDestroy(ThreadState *thr, uptr pc, uptr addr) {
+void MutexDestroy(ThreadState *thr, uptr pc, uptr addr, u32 flagz) {
   DPrintf("#%d: MutexDestroy %zx\n", thr->tid, addr);
   StatInc(thr, StatMutexDestroy);
   SyncVar *s = ctx->metamap.GetIfExistsAndLock(addr, true);
   if (s == 0)
     return;
-  if (s->IsFlagSet(MutexFlagLinkerInit)) {
+  if ((flagz & MutexFlagLinkerInit) || s->IsFlagSet(MutexFlagLinkerInit)) {
     // Destroy is no-op for linker-initialized mutexes.
     s->mtx.Unlock();
     return;