[tsan] Fix weakly imported functions on OS X

[kubamracek]

Summary

On OS X, for weak function (that user can override by providing their own implementation in the main binary), we need extern "C" SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE NOINLINE.

Fixes a broken test case on OS X, java_symbolization.cc, which uses a weak function __tsan_symbolize_external.

[dvyukov]

LGTM with nit

lib/sanitizer_common/sanitizer_internal_defs.h

120–123

also remove CPP_WEAK macro in tsan_defs.h
it was defined to WEAK

[kubamracek]

The previous patch failed several unit tests, because OnReport needs to be exported as a C++ symbol (in __tsan namespace). Changing the patch to have both SANITIZER_WEAK_DEFAULT_IMPL (for C symbols) and SANITIZER_WEAK_CXX_DEFAULT_IMPL (for C++ symbols).

[kubamracek]

ping

lib/sanitizer_common/sanitizer_internal_defs.h

 
 using namespace __sanitizer;  // NOLINT
 // ----------- ATTENTION -------------
 // This header should NOT include any other headers to avoid portability issues.
 
 // Common defs.
 #define INLINE inline
 #define INTERFACE_ATTRIBUTE SANITIZER_INTERFACE_ATTRIBUTE
-#define WEAK SANITIZER_WEAK_ATTRIBUTE
+#define SANITIZER_WEAK_DEFAULT_IMPL \
+  extern "C" SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE NOINLINE
+#define SANITIZER_WEAK_CXX_DEFAULT_IMPL \
+  extern "C++" SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE NOINLINE
 
 // Platform-specific defs.
 #if defined(_MSC_VER)
 # define ALWAYS_INLINE __forceinline
 // FIXME(timurrrr): do we need this on Windows?
 # define ALIAS(x)
 # define ALIGNED(x) __declspec(align(x))
 # define FORMAT(f, a)

lib/tsan/rtl/tsan_defs.h

 #endif
 
 namespace __tsan {
 
 #ifdef SANITIZER_GO
 const bool kGoMode = true;
 const bool kCppMode = false;
 const char *const kTsanOptionsEnv = "GORACE";
-// Go linker does not support weak symbols.
-#define CPP_WEAK
 #else
 const bool kGoMode = false;
 const bool kCppMode = true;
 const char *const kTsanOptionsEnv = "TSAN_OPTIONS";
-#define CPP_WEAK WEAK
 #endif
 
 const int kTidBits = 13;
 const unsigned kMaxTid = 1 << kTidBits;
 #ifndef SANITIZER_GO
 const unsigned kMaxTidInClock = kMaxTid * 2;  // This includes msb 'freed' bit.
 #else
 const unsigned kMaxTidInClock = kMaxTid;  // Go does not track freed memory.

lib/tsan/rtl/tsan_flags.cc

 Flags *flags() {
   return &ctx->flags;
 }
 
 // Can be overriden in frontend.
 #ifdef TSAN_EXTERNAL_HOOKS
 extern "C" const char* __tsan_default_options();
 #else
-extern "C" SANITIZER_INTERFACE_ATTRIBUTE
-const char *WEAK __tsan_default_options() {
+SANITIZER_WEAK_DEFAULT_IMPL
+const char *__tsan_default_options() {
   return "";
 }
 #endif
 
 void Flags::SetDefaults() {
 #define TSAN_FLAG(Type, Name, DefaultValue, Description) Name = DefaultValue;
 #include "tsan_flags.inc"
 #undef TSAN_FLAG

lib/tsan/rtl/tsan_mman.cc

 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_placement_new.h"
 #include "tsan_mman.h"
 #include "tsan_rtl.h"
 #include "tsan_report.h"
 #include "tsan_flags.h"
 
 // May be overriden by front-end.
-extern "C" void WEAK __sanitizer_malloc_hook(void *ptr, uptr size) {
+SANITIZER_WEAK_DEFAULT_IMPL
+void __sanitizer_malloc_hook(void *ptr, uptr size) {
   (void)ptr;
   (void)size;
 }
 
-extern "C" void WEAK __sanitizer_free_hook(void *ptr) {
+SANITIZER_WEAK_DEFAULT_IMPL
+void __sanitizer_free_hook(void *ptr) {
   (void)ptr;
 }
 
 namespace __tsan {
 
 struct MapUnmapCallback {
   void OnMap(uptr p, uptr size) const { }
   void OnUnmap(uptr p, uptr size) const {

lib/tsan/rtl/tsan_rtl.cc

 static char ctx_placeholder[sizeof(Context)] ALIGNED(64);
 Context *ctx;
 
 // Can be overriden by a front-end.
 #ifdef TSAN_EXTERNAL_HOOKS
 bool OnFinalize(bool failed);
 void OnInitialize();
 #else
-SANITIZER_INTERFACE_ATTRIBUTE
-bool WEAK OnFinalize(bool failed) {
+SANITIZER_WEAK_CXX_DEFAULT_IMPL
+bool OnFinalize(bool failed) {
   return failed;
 }
-SANITIZER_INTERFACE_ATTRIBUTE
-void WEAK OnInitialize() {}
+SANITIZER_WEAK_CXX_DEFAULT_IMPL
+void OnInitialize() {}
 #endif
 
 static char thread_registry_placeholder[sizeof(ThreadRegistry)];
 
 static ThreadContextBase *CreateThreadContext(u32 tid) {
   // Map thread trace when context is created.
   char name[50];
   internal_snprintf(name, sizeof(name), "trace %u", tid);

lib/tsan/rtl/tsan_rtl_report.cc

void TsanCheckFailed(const char *file, int line, const char *cond,
   PrintCurrentStackSlow(StackTrace::GetCurrentPc());
   Die();
 }
 
 // Can be overriden by an application/test to intercept reports.
 #ifdef TSAN_EXTERNAL_HOOKS
 bool OnReport(const ReportDesc *rep, bool suppressed);
 #else
-SANITIZER_INTERFACE_ATTRIBUTE
-bool WEAK OnReport(const ReportDesc *rep, bool suppressed) {
+SANITIZER_WEAK_CXX_DEFAULT_IMPL
+bool OnReport(const ReportDesc *rep, bool suppressed) {
   (void)rep;
   return suppressed;
 }
 #endif
 
 static void StackStripMain(SymbolizedStack *frames) {
   SymbolizedStack *last_frame = nullptr;
   SymbolizedStack *last_frame2 = nullptr;

lib/tsan/rtl/tsan_suppressions.cc

 "race:^_M_rep$\n"
 "race:^_M_is_leaked$\n"
 // False positive when using std <thread>.
 // Happens because we miss atomic synchronization in libstdc++.
 // See http://llvm.org/bugs/show_bug.cgi?id=17066 for details.
 "race:std::_Sp_counted_ptr_inplace<std::thread::_Impl\n";
 
 // Can be overriden in frontend.
-extern "C" const char *WEAK __tsan_default_suppressions() {
+SANITIZER_WEAK_DEFAULT_IMPL
+const char *__tsan_default_suppressions() {
   return 0;
 }
 #endif
 
 namespace __tsan {
 
 ALIGNED(64) static char suppression_placeholder[sizeof(SuppressionContext)];
 static SuppressionContext *suppression_ctx = nullptr;

lib/tsan/rtl/tsan_symbolize.cc

void ExitSymbolizer() {
   ThreadState *thr = cur_thread();
   CHECK(thr->in_symbolizer);
   thr->in_symbolizer = false;
   thr->ignore_interceptors--;
 }
 
 // May be overriden by JIT/JAVA/etc,
 // whatever produces PCs marked with kExternalPCBit.
-extern "C" bool WEAK __tsan_symbolize_external(uptr pc,
-                                               char *func_buf, uptr func_siz,
-                                               char *file_buf, uptr file_siz,
-                                               int *line, int *col) {
+SANITIZER_WEAK_DEFAULT_IMPL
+bool __tsan_symbolize_external(uptr pc, char *func_buf, uptr func_siz,
+                               char *file_buf, uptr file_siz, int *line,
+                               int *col) {
   return false;
 }
 
 SymbolizedStack *SymbolizeCode(uptr addr) {
   // Check if PC comes from non-native land.
   if (addr & kExternalPCBit) {
     // Declare static to not consume too much stack space.
     // We symbolize reports in a single thread, so this is fine.