181 lines · cpp
1//===--------- RegisterEHFrames.cpp - Register EH frame sections ----------===//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#include "llvm/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.h"10 11#include "llvm/Config/config.h"12#include "llvm/Support/Compiler.h"13#include "llvm/Support/DynamicLibrary.h"14#include "llvm/Support/raw_ostream.h"15 16#define DEBUG_TYPE "orc"17 18using namespace llvm;19using namespace llvm::orc;20using namespace llvm::orc::shared;21 22namespace llvm {23namespace orc {24 25#if defined(HAVE_REGISTER_FRAME) && defined(HAVE_DEREGISTER_FRAME) && \26 !defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)27 28extern "C" void __register_frame(const void *);29extern "C" void __deregister_frame(const void *);30 31Error registerFrameWrapper(const void *P) {32 __register_frame(P);33 return Error::success();34}35 36Error deregisterFrameWrapper(const void *P) {37 __deregister_frame(P);38 return Error::success();39}40 41#else42 43// The building compiler does not have __(de)register_frame but44// it may be found at runtime in a dynamically-loaded library.45// For example, this happens when building LLVM with Visual C++46// but using the MingW runtime.47static Error registerFrameWrapper(const void *P) {48 static void((*RegisterFrame)(const void *)) = 0;49 50 if (!RegisterFrame)51 *(void **)&RegisterFrame =52 llvm::sys::DynamicLibrary::SearchForAddressOfSymbol("__register_frame");53 54 if (RegisterFrame) {55 RegisterFrame(P);56 return Error::success();57 }58 59 return make_error<StringError>("could not register eh-frame: "60 "__register_frame function not found",61 inconvertibleErrorCode());62}63 64static Error deregisterFrameWrapper(const void *P) {65 static void((*DeregisterFrame)(const void *)) = 0;66 67 if (!DeregisterFrame)68 *(void **)&DeregisterFrame =69 llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(70 "__deregister_frame");71 72 if (DeregisterFrame) {73 DeregisterFrame(P);74 return Error::success();75 }76 77 return make_error<StringError>("could not deregister eh-frame: "78 "__deregister_frame function not found",79 inconvertibleErrorCode());80}81#endif82 83#if defined(HAVE_UNW_ADD_DYNAMIC_FDE) || defined(__APPLE__)84 85template <typename HandleFDEFn>86Error walkLibunwindEHFrameSection(const char *const SectionStart,87 size_t SectionSize, HandleFDEFn HandleFDE) {88 const char *CurCFIRecord = SectionStart;89 const char *End = SectionStart + SectionSize;90 uint64_t Size = *reinterpret_cast<const uint32_t *>(CurCFIRecord);91 92 while (CurCFIRecord != End && Size != 0) {93 const char *OffsetField = CurCFIRecord + (Size == 0xffffffff ? 12 : 4);94 if (Size == 0xffffffff)95 Size = *reinterpret_cast<const uint64_t *>(CurCFIRecord + 4) + 12;96 else97 Size += 4;98 uint32_t Offset = *reinterpret_cast<const uint32_t *>(OffsetField);99 100 LLVM_DEBUG({101 dbgs() << "Registering eh-frame section:\n";102 dbgs() << "Processing " << (Offset ? "FDE" : "CIE") << " @"103 << (void *)CurCFIRecord << ": [";104 for (unsigned I = 0; I < Size; ++I)105 dbgs() << format(" 0x%02" PRIx8, *(CurCFIRecord + I));106 dbgs() << " ]\n";107 });108 109 if (Offset != 0)110 if (auto Err = HandleFDE(CurCFIRecord))111 return Err;112 113 CurCFIRecord += Size;114 115 Size = *reinterpret_cast<const uint32_t *>(CurCFIRecord);116 }117 118 return Error::success();119}120 121#endif // HAVE_UNW_ADD_DYNAMIC_FDE || __APPLE__122 123Error registerEHFrameSection(const void *EHFrameSectionAddr,124 size_t EHFrameSectionSize) {125 /* libgcc and libunwind __register_frame behave differently. We use the126 * presence of __unw_add_dynamic_fde to detect libunwind. */127#if defined(HAVE_UNW_ADD_DYNAMIC_FDE) || defined(__APPLE__)128 // With libunwind, __register_frame has to be called for each FDE entry.129 return walkLibunwindEHFrameSection(130 static_cast<const char *>(EHFrameSectionAddr), EHFrameSectionSize,131 registerFrameWrapper);132#else133 // With libgcc, __register_frame takes a single argument:134 // a pointer to the start of the .eh_frame section.135 136 // How can it find the end? Because crtendS.o is linked137 // in and it has an .eh_frame section with four zero chars.138 return registerFrameWrapper(EHFrameSectionAddr);139#endif140}141 142Error deregisterEHFrameSection(const void *EHFrameSectionAddr,143 size_t EHFrameSectionSize) {144#if defined(HAVE_UNW_ADD_DYNAMIC_FDE) || defined(__APPLE__)145 return walkLibunwindEHFrameSection(146 static_cast<const char *>(EHFrameSectionAddr), EHFrameSectionSize,147 deregisterFrameWrapper);148#else149 return deregisterFrameWrapper(EHFrameSectionAddr);150#endif151}152 153} // end namespace orc154} // end namespace llvm155 156static Error registerEHFrameWrapper(ExecutorAddrRange EHFrame) {157 return llvm::orc::registerEHFrameSection(EHFrame.Start.toPtr<const void *>(),158 EHFrame.size());159}160 161static Error deregisterEHFrameWrapper(ExecutorAddrRange EHFrame) {162 return llvm::orc::deregisterEHFrameSection(163 EHFrame.Start.toPtr<const void *>(), EHFrame.size());164}165 166extern "C" orc::shared::CWrapperFunctionResult167llvm_orc_registerEHFrameSectionAllocAction(const char *ArgData,168 size_t ArgSize) {169 return WrapperFunction<SPSError(SPSExecutorAddrRange)>::handle(170 ArgData, ArgSize, registerEHFrameWrapper)171 .release();172}173 174extern "C" orc::shared::CWrapperFunctionResult175llvm_orc_deregisterEHFrameSectionAllocAction(const char *ArgData,176 size_t ArgSize) {177 return WrapperFunction<SPSError(SPSExecutorAddrRange)>::handle(178 ArgData, ArgSize, deregisterEHFrameWrapper)179 .release();180}181