Differential D22611 Diff 64832 compiler-rt/trunk/lib/xray/xray_init.cc

Changeset View

Standalone View

compiler-rt/trunk/lib/xray/xray_init.cc

				//===-- xray_init.cc --------------------------------------------- C++ --===//
				//
				// The LLVM Compiler Infrastructure
				//
				// This file is distributed under the University of Illinois Open Source
				// License. See LICENSE.TXT for details.
				//
				//===----------------------------------------------------------------------===//
				//
				// This file is a part of XRay, a dynamic runtime instrumentation system.
				//
				// XRay initialisation logic.
				//===----------------------------------------------------------------------===//

				#include <atomic>
				#include <fcntl.h>
				#include <strings.h>
				#include <unistd.h>

				#include "sanitizer_common/sanitizer_common.h"
				#include "xray_flags.h"
				#include "xray_interface_internal.h"

				extern "C" {
				extern void __xray_init();
				extern const XRaySledEntry __start_xray_instr_map[] __attribute__((weak));
				extern const XRaySledEntry __stop_xray_instr_map[] __attribute__((weak));
				}

				using namespace __xray;

				// We initialize some global variables that pertain to specific sections of XRay
				// data structures in the binary. We do this for the current process using
				// /proc/curproc/map and make sure that we're able to get it. We signal failure
				// via a global atomic boolean to indicate whether we've initialized properly.
				//
				std::atomic<bool> XRayInitialized{false};

				// This should always be updated before XRayInitialized is updated.
				std::atomic<__xray::XRaySledMap> XRayInstrMap{};

				// __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() {
				InitializeFlags();
				if (__start_xray_instr_map == nullptr) {
				Report("XRay instrumentation map missing. Not initializing XRay.\n");
				return;
				}

				// Now initialize the XRayInstrMap global struct with the address of the
				// entries, reinterpreted as an array of XRaySledEntry objects. We use the
				// virtual pointer we have from the section to provide us the correct
				// information.
				__xray::XRaySledMap SledMap{};
				SledMap.Sleds = __start_xray_instr_map;
				SledMap.Entries = __stop_xray_instr_map - __start_xray_instr_map;
				XRayInstrMap.store(SledMap, std::memory_order_release);
				XRayInitialized.store(true, std::memory_order_release);

				if (flags()->patch_premain)
				__xray_patch();
				}

				__attribute__((section(".preinit_array"),
				used)) void (*__local_xray_preinit)(void) = __xray_init;