[UBSan] Call UBSan initialization as early as possible.

Specifically, use .preinit_array initialization on Linux and dynamic global
initializer on another platforms. Historically UBSan didn't have any
initialization code and its runtime was stateless. This is no longer the
case - UBSan relies on some non-trivial functionality from sanitizer_common
(e.g. online symbolization) and is now configurable by runtime flags.
Additionally, we've dropped support for enabling UBSan only for a few shared
objects, so UBSan is now always linked into the main executable, so now
we can use similar initialization as all the rest sanitizers.

llvm-svn: 213983

1 files changed, 63 insertions, 0 deletions

diff --git a/compiler-rt/lib/ubsan/ubsan_init.cc b/compiler-rt/lib/ubsan/ubsan_init.cc
new file mode 100644
index 00000000000..9cfd42f3d0d
--- /dev/null
+++ b/compiler-rt/lib/ubsan/ubsan_init.cc
@@ -0,0 +1,63 @@
+//===-- ubsan_init.cc -----------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Initialization of UBSan runtime.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ubsan_init.h"
+#include "ubsan_flags.h"
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_libc.h"
+#include "sanitizer_common/sanitizer_flags.h"
+#include "sanitizer_common/sanitizer_mutex.h"
+
+using namespace __ubsan;
+
+static bool ubsan_inited;
+
+void __ubsan::InitIfNecessary() {
+#if !SANITIZER_CAN_USE_PREINIT_ARRAY
+  // No need to lock mutex if we're initializing from preinit array.
+  static StaticSpinMutex init_mu;
+  SpinMutexLock l(&init_mu);
+#endif
+  if (LIKELY(ubsan_inited))
+   return;
+  if (0 == internal_strcmp(SanitizerToolName, "SanitizerTool")) {
+    // WARNING: If this condition holds, then either UBSan runs in a standalone
+    // mode, or initializer for another sanitizer hasn't run yet. In a latter
+    // case, another sanitizer will overwrite "SanitizerToolName" and reparse
+    // common flags. It means, that we are not allowed to *use* common flags
+    // in this function.
+    SanitizerToolName = "UndefinedBehaviorSanitizer";
+    CommonFlags *cf = common_flags();
+    SetCommonFlagsDefaults(cf);
+    cf->print_summary = false;
+    // Common flags may only be modified via UBSAN_OPTIONS.
+    ParseCommonFlagsFromString(cf, GetEnv("UBSAN_OPTIONS"));
+  }
+  // Initialize UBSan-specific flags.
+  InitializeFlags();
+  ubsan_inited = true;
+}
+
+#if SANITIZER_CAN_USE_PREINIT_ARRAY
+__attribute__((section(".preinit_array"), used))
+void (*__local_ubsan_preinit)(void) = __ubsan::InitIfNecessary;
+#else
+// Use a dynamic initializer.
+class UbsanInitializer {
+ public:
+  UbsanInitializer() {
+    InitIfNecessary();
+  }
+};
+static UbsanInitializer ubsan_initializer;
+#endif  // SANITIZER_CAN_USE_PREINIT_ARRAY