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132 lines
4.6 KiB
132 lines
4.6 KiB
//===-- xray_init.cpp -------------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of XRay, a dynamic runtime instrumentation system.
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//
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// XRay initialisation logic.
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//===----------------------------------------------------------------------===//
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#include <fcntl.h>
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#include <strings.h>
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#include <unistd.h>
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#include "sanitizer_common/sanitizer_common.h"
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#include "xray_defs.h"
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#include "xray_flags.h"
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#include "xray_interface_internal.h"
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extern "C" {
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void __xray_init();
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extern const XRaySledEntry __start_xray_instr_map[] __attribute__((weak));
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extern const XRaySledEntry __stop_xray_instr_map[] __attribute__((weak));
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extern const XRayFunctionSledIndex __start_xray_fn_idx[] __attribute__((weak));
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extern const XRayFunctionSledIndex __stop_xray_fn_idx[] __attribute__((weak));
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#if SANITIZER_MAC
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// HACK: This is a temporary workaround to make XRay build on
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// Darwin, but it will probably not work at runtime.
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const XRaySledEntry __start_xray_instr_map[] = {};
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extern const XRaySledEntry __stop_xray_instr_map[] = {};
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extern const XRayFunctionSledIndex __start_xray_fn_idx[] = {};
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extern const XRayFunctionSledIndex __stop_xray_fn_idx[] = {};
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#endif
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}
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using namespace __xray;
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// When set to 'true' this means the XRay runtime has been initialised. We use
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// the weak symbols defined above (__start_xray_inst_map and
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// __stop_xray_instr_map) to initialise the instrumentation map that XRay uses
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// for runtime patching/unpatching of instrumentation points.
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//
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// FIXME: Support DSO instrumentation maps too. The current solution only works
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// for statically linked executables.
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atomic_uint8_t XRayInitialized{0};
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// This should always be updated before XRayInitialized is updated.
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SpinMutex XRayInstrMapMutex;
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XRaySledMap XRayInstrMap;
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// Global flag to determine whether the flags have been initialized.
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atomic_uint8_t XRayFlagsInitialized{0};
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// A mutex to allow only one thread to initialize the XRay data structures.
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SpinMutex XRayInitMutex;
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// __xray_init() will do the actual loading of the current process' memory map
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// and then proceed to look for the .xray_instr_map section/segment.
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void __xray_init() XRAY_NEVER_INSTRUMENT {
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SpinMutexLock Guard(&XRayInitMutex);
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// Short-circuit if we've already initialized XRay before.
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if (atomic_load(&XRayInitialized, memory_order_acquire))
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return;
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// XRAY is not compatible with PaX MPROTECT
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CheckMPROTECT();
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if (!atomic_load(&XRayFlagsInitialized, memory_order_acquire)) {
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initializeFlags();
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atomic_store(&XRayFlagsInitialized, true, memory_order_release);
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}
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if (__start_xray_instr_map == nullptr) {
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if (Verbosity())
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Report("XRay instrumentation map missing. Not initializing XRay.\n");
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return;
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}
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{
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SpinMutexLock Guard(&XRayInstrMapMutex);
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XRayInstrMap.Sleds = __start_xray_instr_map;
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XRayInstrMap.Entries = __stop_xray_instr_map - __start_xray_instr_map;
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if (__start_xray_fn_idx != nullptr) {
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XRayInstrMap.SledsIndex = __start_xray_fn_idx;
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XRayInstrMap.Functions = __stop_xray_fn_idx - __start_xray_fn_idx;
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} else {
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size_t CountFunctions = 0;
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uint64_t LastFnAddr = 0;
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for (std::size_t I = 0; I < XRayInstrMap.Entries; I++) {
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const auto &Sled = XRayInstrMap.Sleds[I];
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const auto Function = Sled.function();
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if (Function != LastFnAddr) {
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CountFunctions++;
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LastFnAddr = Function;
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}
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}
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XRayInstrMap.Functions = CountFunctions;
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}
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}
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atomic_store(&XRayInitialized, true, memory_order_release);
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#ifndef XRAY_NO_PREINIT
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if (flags()->patch_premain)
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__xray_patch();
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#endif
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}
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// FIXME: Make check-xray tests work on FreeBSD without
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// SANITIZER_CAN_USE_PREINIT_ARRAY.
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// See sanitizer_internal_defs.h where the macro is defined.
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// Calling unresolved PLT functions in .preinit_array can lead to deadlock on
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// FreeBSD but here it seems benign.
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#if !defined(XRAY_NO_PREINIT) && \
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(SANITIZER_CAN_USE_PREINIT_ARRAY || SANITIZER_FREEBSD)
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// Only add the preinit array initialization if the sanitizers can.
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__attribute__((section(".preinit_array"),
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used)) void (*__local_xray_preinit)(void) = __xray_init;
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#else
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// If we cannot use the .preinit_array section, we should instead use dynamic
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// initialisation.
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__attribute__ ((constructor (0)))
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static void __local_xray_dyninit() {
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__xray_init();
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}
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#endif
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