1 files changed, 115 insertions, 0 deletions
diff --git a/lib/xray/xray_init.cpp b/lib/xray/xray_init.cpp
new file mode 100644
index 000000000000..408396477975
--- /dev/null
+++ b/lib/xray/xray_init.cpp
@@ -0,0 +1,115 @@
+//===-- xray_init.cpp -------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of XRay, a dynamic runtime instrumentation system.
+//
+// XRay initialisation logic.
+//===----------------------------------------------------------------------===//
+
+#include <fcntl.h>
+#include <strings.h>
+#include <unistd.h>
+
+#include "sanitizer_common/sanitizer_common.h"
+#include "xray_defs.h"
+#include "xray_flags.h"
+#include "xray_interface_internal.h"
+
+extern "C" {
+void __xray_init();
+extern const XRaySledEntry __start_xray_instr_map[] __attribute__((weak));
+extern const XRaySledEntry __stop_xray_instr_map[] __attribute__((weak));
+extern const XRayFunctionSledIndex __start_xray_fn_idx[] __attribute__((weak));
+extern const XRayFunctionSledIndex __stop_xray_fn_idx[] __attribute__((weak));
+
+#if SANITIZER_MAC
+// HACK: This is a temporary workaround to make XRay build on 
+// Darwin, but it will probably not work at runtime.
+const XRaySledEntry __start_xray_instr_map[] = {};
+extern const XRaySledEntry __stop_xray_instr_map[] = {};
+extern const XRayFunctionSledIndex __start_xray_fn_idx[] = {};
+extern const XRayFunctionSledIndex __stop_xray_fn_idx[] = {};
+#endif
+}
+
+using namespace __xray;
+
+// When set to 'true' this means the XRay runtime has been initialised. We use
+// the weak symbols defined above (__start_xray_inst_map and
+// __stop_xray_instr_map) to initialise the instrumentation map that XRay uses
+// for runtime patching/unpatching of instrumentation points.
+//
+// FIXME: Support DSO instrumentation maps too. The current solution only works
+// for statically linked executables.
+atomic_uint8_t XRayInitialized{0};
+
+// This should always be updated before XRayInitialized is updated.
+SpinMutex XRayInstrMapMutex;
+XRaySledMap XRayInstrMap;
+
+// Global flag to determine whether the flags have been initialized.
+atomic_uint8_t XRayFlagsInitialized{0};
+
+// A mutex to allow only one thread to initialize the XRay data structures.
+SpinMutex XRayInitMutex;
+
+// __xray_init() will do the actual loading of the current process' memory map
+// and then proceed to look for the .xray_instr_map section/segment.
+void __xray_init() XRAY_NEVER_INSTRUMENT {
+  SpinMutexLock Guard(&XRayInitMutex);
+  // Short-circuit if we've already initialized XRay before.
+  if (atomic_load(&XRayInitialized, memory_order_acquire))
+    return;
+
+  // XRAY is not compatible with PaX MPROTECT
+  CheckMPROTECT();
+
+  if (!atomic_load(&XRayFlagsInitialized, memory_order_acquire)) {
+    initializeFlags();
+    atomic_store(&XRayFlagsInitialized, true, memory_order_release);
+  }
+
+  if (__start_xray_instr_map == nullptr) {
+    if (Verbosity())
+      Report("XRay instrumentation map missing. Not initializing XRay.\n");
+    return;
+  }
+
+  {
+    SpinMutexLock Guard(&XRayInstrMapMutex);
+    XRayInstrMap.Sleds = __start_xray_instr_map;
+    XRayInstrMap.Entries = __stop_xray_instr_map - __start_xray_instr_map;
+    XRayInstrMap.SledsIndex = __start_xray_fn_idx;
+    XRayInstrMap.Functions = __stop_xray_fn_idx - __start_xray_fn_idx;
+  }
+  atomic_store(&XRayInitialized, true, memory_order_release);
+
+#ifndef XRAY_NO_PREINIT
+  if (flags()->patch_premain)
+    __xray_patch();
+#endif
+}
+
+// FIXME: Make check-xray tests work on FreeBSD without
+// SANITIZER_CAN_USE_PREINIT_ARRAY.
+// See sanitizer_internal_defs.h where the macro is defined.
+// Calling unresolved PLT functions in .preinit_array can lead to deadlock on
+// FreeBSD but here it seems benign.
+#if !defined(XRAY_NO_PREINIT) &&                                               \
+    (SANITIZER_CAN_USE_PREINIT_ARRAY || SANITIZER_FREEBSD)
+// Only add the preinit array initialization if the sanitizers can.
+__attribute__((section(".preinit_array"),
+               used)) void (*__local_xray_preinit)(void) = __xray_init;
+#else
+// If we cannot use the .preinit_array section, we should instead use dynamic
+// initialisation.
+__attribute__ ((constructor (0)))
+static void __local_xray_dyninit() {
+  __xray_init();
+}
+#endif