Stephen Hines | 6f75755 | 2013-03-04 19:51:03 -0800 | [diff] [blame] | 1 | //===- ELFReader.cpp ------------------------------------------------------===// |
| 2 | // |
| 3 | // The MCLinker Project |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | #include <mcld/LD/ELFReaderIf.h> |
| 10 | |
| 11 | #include <mcld/IRBuilder.h> |
| 12 | #include <mcld/Fragment/FillFragment.h> |
| 13 | #include <mcld/LD/EhFrame.h> |
| 14 | #include <mcld/LD/SectionData.h> |
| 15 | #include <mcld/Target/GNULDBackend.h> |
Stephen Hines | 6f75755 | 2013-03-04 19:51:03 -0800 | [diff] [blame] | 16 | |
| 17 | #include <cstring> |
| 18 | |
| 19 | #include <llvm/ADT/StringRef.h> |
| 20 | #include <llvm/ADT/Twine.h> |
| 21 | #include <llvm/Support/ELF.h> |
| 22 | #include <llvm/Support/Host.h> |
| 23 | |
| 24 | using namespace mcld; |
| 25 | |
| 26 | //===----------------------------------------------------------------------===// |
| 27 | // ELFReaderIF |
| 28 | //===----------------------------------------------------------------------===// |
| 29 | /// getSymType |
| 30 | ResolveInfo::Type ELFReaderIF::getSymType(uint8_t pInfo, uint16_t pShndx) const |
| 31 | { |
| 32 | ResolveInfo::Type result = static_cast<ResolveInfo::Type>(pInfo & 0xF); |
| 33 | if (llvm::ELF::SHN_ABS == pShndx && ResolveInfo::Section == result) { |
| 34 | // In Mips, __gp_disp is a special section symbol. Its name comes from |
| 35 | // .strtab, not .shstrtab. However, it is unique. Only it is also a ABS |
| 36 | // symbol. So here is a tricky to identify __gp_disp and convert it to |
| 37 | // Object symbol. |
| 38 | return ResolveInfo::Object; |
| 39 | } |
| 40 | |
| 41 | return result; |
| 42 | } |
| 43 | |
| 44 | /// getSymDesc |
| 45 | ResolveInfo::Desc ELFReaderIF::getSymDesc(uint16_t pShndx, const Input& pInput) const |
| 46 | { |
| 47 | if (pShndx == llvm::ELF::SHN_UNDEF) |
| 48 | return ResolveInfo::Undefined; |
| 49 | |
| 50 | if (pShndx < llvm::ELF::SHN_LORESERVE) { |
| 51 | // an ELF symbol defined in a section which we are not including |
| 52 | // must be treated as an Undefined. |
| 53 | // @ref Google gold linker: symtab.cc: 1086 |
| 54 | if (NULL == pInput.context()->getSection(pShndx) || |
| 55 | LDFileFormat::Ignore == pInput.context()->getSection(pShndx)->kind()) |
| 56 | return ResolveInfo::Undefined; |
| 57 | return ResolveInfo::Define; |
| 58 | } |
| 59 | |
| 60 | if (pShndx == llvm::ELF::SHN_ABS) |
| 61 | return ResolveInfo::Define; |
| 62 | |
| 63 | if (pShndx == llvm::ELF::SHN_COMMON) |
| 64 | return ResolveInfo::Common; |
| 65 | |
| 66 | if (pShndx >= llvm::ELF::SHN_LOPROC && |
| 67 | pShndx <= llvm::ELF::SHN_HIPROC) |
| 68 | return target().getSymDesc(pShndx); |
| 69 | |
| 70 | // FIXME: ELF weak alias should be ResolveInfo::Indirect |
| 71 | return ResolveInfo::NoneDesc; |
| 72 | } |
| 73 | |
| 74 | /// getSymBinding |
| 75 | ResolveInfo::Binding |
| 76 | ELFReaderIF::getSymBinding(uint8_t pBinding, uint16_t pShndx, uint8_t pVis) const |
| 77 | { |
| 78 | |
| 79 | // TODO: |
| 80 | // if --just-symbols option is enabled, the symbol must covert to Absolute |
| 81 | |
| 82 | switch(pBinding) { |
| 83 | case llvm::ELF::STB_LOCAL: |
| 84 | return ResolveInfo::Local; |
| 85 | case llvm::ELF::STB_GLOBAL: |
Stephen Hines | f7ac0f1 | 2013-05-03 19:09:24 -0700 | [diff] [blame] | 86 | if (pShndx == llvm::ELF::SHN_ABS) |
| 87 | return ResolveInfo::Absolute; |
Stephen Hines | 6f75755 | 2013-03-04 19:51:03 -0800 | [diff] [blame] | 88 | return ResolveInfo::Global; |
| 89 | case llvm::ELF::STB_WEAK: |
| 90 | return ResolveInfo::Weak; |
| 91 | } |
| 92 | |
Stephen Hines | 6f75755 | 2013-03-04 19:51:03 -0800 | [diff] [blame] | 93 | return ResolveInfo::NoneBinding; |
| 94 | } |
| 95 | |
| 96 | /// getSymFragmentRef |
| 97 | FragmentRef* |
| 98 | ELFReaderIF::getSymFragmentRef(Input& pInput, |
| 99 | uint16_t pShndx, |
| 100 | uint32_t pOffset) const |
| 101 | { |
| 102 | |
| 103 | if (Input::DynObj == pInput.type()) |
| 104 | return FragmentRef::Null(); |
| 105 | |
| 106 | if (pShndx == llvm::ELF::SHN_UNDEF) |
| 107 | return FragmentRef::Null(); |
| 108 | |
| 109 | if (pShndx >= llvm::ELF::SHN_LORESERVE) // including ABS and COMMON |
| 110 | return FragmentRef::Null(); |
| 111 | |
| 112 | LDSection* sect_hdr = pInput.context()->getSection(pShndx); |
| 113 | |
| 114 | if (NULL == sect_hdr) |
| 115 | unreachable(diag::unreachable_invalid_section_idx) << pShndx |
| 116 | << pInput.path().native(); |
| 117 | |
| 118 | if (LDFileFormat::Ignore == sect_hdr->kind()) |
| 119 | return FragmentRef::Null(); |
| 120 | |
| 121 | if (LDFileFormat::Group == sect_hdr->kind()) |
| 122 | return FragmentRef::Null(); |
| 123 | |
| 124 | return FragmentRef::Create(*sect_hdr, pOffset); |
| 125 | } |
| 126 | |
| 127 | /// getSymVisibility |
| 128 | ResolveInfo::Visibility |
| 129 | ELFReaderIF::getSymVisibility(uint8_t pVis) const |
| 130 | { |
| 131 | return static_cast<ResolveInfo::Visibility>(pVis); |
| 132 | } |
| 133 | |
| 134 | /// getSymValue - get the section offset of the symbol. |
| 135 | uint64_t ELFReaderIF::getSymValue(uint64_t pValue, |
| 136 | uint16_t pShndx, |
| 137 | const Input& pInput) const |
| 138 | { |
| 139 | if (Input::Object == pInput.type()) { |
| 140 | // In relocatable files, st_value holds alignment constraints for a symbol |
| 141 | // whose section index is SHN_COMMON |
| 142 | if (pShndx == llvm::ELF::SHN_COMMON || pShndx == llvm::ELF::SHN_ABS) { |
| 143 | return pValue; |
| 144 | } |
| 145 | |
| 146 | // In relocatable files, st_value holds a section offset for a defined symbol. |
| 147 | // TODO: |
| 148 | // if --just-symbols option are enabled, convert the value from section offset |
| 149 | // to virtual address by adding input section's virtual address. |
| 150 | // The section's virtual address in relocatable files is normally zero, but |
| 151 | // people can use link script to change it. |
| 152 | return pValue; |
| 153 | } |
| 154 | |
| 155 | // In executable and shared object files, st_value holds a virtual address. |
Stephen Hines | f7ac0f1 | 2013-05-03 19:09:24 -0700 | [diff] [blame] | 156 | // the virtual address is needed for alias identification. |
| 157 | return pValue; |
Stephen Hines | 6f75755 | 2013-03-04 19:51:03 -0800 | [diff] [blame] | 158 | } |
| 159 | |