162 lines · cpp
1//===-- ubsan_value.cpp ---------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// Representation of a runtime value, as marshaled from the generated code to10// the ubsan runtime.11//12//===----------------------------------------------------------------------===//13 14#include "ubsan_platform.h"15#if CAN_SANITIZE_UB16#include "ubsan_value.h"17#include "sanitizer_common/sanitizer_common.h"18#include "sanitizer_common/sanitizer_libc.h"19#include "sanitizer_common/sanitizer_mutex.h"20 21#if SANITIZER_APPLE22#include <dlfcn.h>23#endif24 25using namespace __ubsan;26 27typedef const char *(*ObjCGetClassNameTy)(void *);28 29const char *__ubsan::getObjCClassName(ValueHandle Pointer) {30#if SANITIZER_APPLE31 // We need to query the ObjC runtime for some information, but do not want32 // to introduce a static dependency from the ubsan runtime onto ObjC. Try to33 // grab a handle to the ObjC runtime used by the process.34 static bool AttemptedDlopen = false;35 static void *ObjCHandle = nullptr;36 static void *ObjCObjectGetClassName = nullptr;37 38 // Prevent threads from racing to dlopen().39 static __sanitizer::StaticSpinMutex Lock;40 {41 __sanitizer::SpinMutexLock Guard(&Lock);42 43 if (!AttemptedDlopen) {44 ObjCHandle = dlopen(45 "/usr/lib/libobjc.A.dylib",46 RTLD_LAZY // Only bind symbols when used.47 | RTLD_LOCAL // Only make symbols available via the handle.48 | RTLD_NOLOAD // Do not load the dylib, just grab a handle if the49 // image is already loaded.50 | RTLD_FIRST // Only search the image pointed-to by the handle.51 );52 AttemptedDlopen = true;53 if (!ObjCHandle)54 return nullptr;55 ObjCObjectGetClassName = dlsym(ObjCHandle, "object_getClassName");56 }57 }58 59 if (!ObjCObjectGetClassName)60 return nullptr;61 62 return ObjCGetClassNameTy(ObjCObjectGetClassName)((void *)Pointer);63#else64 return nullptr;65#endif66}67 68SIntMax Value::getSIntValue() const {69 CHECK(getType().isSignedIntegerTy());70 // Val was zero-extended to ValueHandle. Sign-extend from original width71 // to SIntMax.72 const unsigned ExtraBits =73 sizeof(SIntMax) * 8 - getType().getIntegerBitCount();74 if (isInlineInt()) {75 return SIntMax(UIntMax(Val) << ExtraBits) >> ExtraBits;76 }77 if (getType().getIntegerBitWidth() == 64) {78 return SIntMax(UIntMax(*reinterpret_cast<s64 *>(Val)) << ExtraBits) >>79 ExtraBits;80 }81#if HAVE_INT128_T82 if (getType().getIntegerBitWidth() == 128)83 return SIntMax(UIntMax(*reinterpret_cast<s128 *>(Val)) << ExtraBits) >>84 ExtraBits;85#else86 if (getType().getIntegerBitWidth() == 128)87 UNREACHABLE("libclang_rt.ubsan was built without __int128 support");88#endif89 UNREACHABLE("unexpected bit width");90}91 92UIntMax Value::getUIntValue() const {93 CHECK(getType().isUnsignedIntegerTy());94 if (isInlineInt())95 return Val;96 if (getType().getIntegerBitWidth() == 64)97 return *reinterpret_cast<u64*>(Val);98#if HAVE_INT128_T99 if (getType().getIntegerBitWidth() == 128)100 return *reinterpret_cast<u128*>(Val);101#else102 if (getType().getIntegerBitWidth() == 128)103 UNREACHABLE("libclang_rt.ubsan was built without __int128 support");104#endif105 UNREACHABLE("unexpected bit width");106}107 108UIntMax Value::getPositiveIntValue() const {109 if (getType().isUnsignedIntegerTy())110 return getUIntValue();111 SIntMax Val = getSIntValue();112 CHECK(Val >= 0);113 return Val;114}115 116/// Get the floating-point value of this object, extended to a long double.117/// These are always passed by address (our calling convention doesn't allow118/// them to be passed in floating-point registers, so this has little cost).119FloatMax Value::getFloatValue() const {120 CHECK(getType().isFloatTy());121 if (isInlineFloat()) {122 switch (getType().getFloatBitWidth()) {123#if 0124 // FIXME: OpenCL / NEON 'half' type. LLVM can't lower the conversion125 // from '__fp16' to 'long double'.126 case 16: {127 __fp16 Value;128 internal_memcpy(&Value, &Val, 4);129 return Value;130 }131#endif132 case 32: {133 float Value;134#if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__135 // For big endian the float value is in the last 4 bytes.136 // On some targets we may only have 4 bytes so we count backwards from137 // the end of Val to account for both the 32-bit and 64-bit cases.138 internal_memcpy(&Value, ((const char*)(&Val + 1)) - 4, 4);139#else140 internal_memcpy(&Value, &Val, 4);141#endif142 return Value;143 }144 case 64: {145 double Value;146 internal_memcpy(&Value, &Val, 8);147 return Value;148 }149 }150 } else {151 switch (getType().getFloatBitWidth()) {152 case 64: return *reinterpret_cast<double*>(Val);153 case 80: return *reinterpret_cast<long double*>(Val);154 case 96: return *reinterpret_cast<long double*>(Val);155 case 128: return *reinterpret_cast<long double*>(Val);156 }157 }158 UNREACHABLE("unexpected floating point bit width");159}160 161#endif // CAN_SANITIZE_UB162