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-rw-r--r--lib/MC/ELFObjectWriter.cpp259
1 files changed, 128 insertions, 131 deletions
diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index e4442e1..4819905 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -31,8 +31,8 @@
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Support/Compression.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/Endian.h"
#include "llvm/Support/ELF.h"
+#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
#include <vector>
using namespace llvm;
@@ -219,7 +219,7 @@ class ELFObjectWriter : public MCObjectWriter {
const MCSymbolData *SD, uint64_t C,
unsigned Type) const;
- void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
+ void RecordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment *Fragment, const MCFixup &Fixup,
MCValue Target, bool &IsPCRel,
uint64_t &FixedValue) override;
@@ -247,12 +247,12 @@ class ELFObjectWriter : public MCObjectWriter {
const RevGroupMapTy &RevGroupMap,
unsigned NumRegularSections);
- void ComputeIndexMap(MCAssembler &Asm,
+ void computeIndexMap(MCAssembler &Asm,
SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap);
+ RelMapTy &RelMap);
- void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout,
- RelMapTy &RelMap);
+ MCSectionData *createRelocationSection(MCAssembler &Asm,
+ const MCSectionData &SD);
void CompressDebugSections(MCAssembler &Asm, MCAsmLayout &Layout);
@@ -260,23 +260,23 @@ class ELFObjectWriter : public MCObjectWriter {
const RelMapTy &RelMap);
void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
- SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap);
+ SectionIndexMapTy &SectionIndexMap);
// Create the sections that show up in the symbol table. Currently
// those are the .note.GNU-stack section and the group sections.
- void CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout,
+ void createIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout,
GroupMapTy &GroupMap,
RevGroupMapTy &RevGroupMap,
SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap);
+ RelMapTy &RelMap);
void ExecutePostLayoutBinding(MCAssembler &Asm,
const MCAsmLayout &Layout) override;
- void WriteSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap,
+ void writeSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap,
const MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap,
const SectionOffsetMapTy &SectionOffsetMap);
void ComputeSectionOrder(MCAssembler &Asm,
@@ -299,8 +299,9 @@ class ELFObjectWriter : public MCObjectWriter {
bool IsPCRel) const override;
void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
- void WriteSection(MCAssembler &Asm,
+ void writeSection(MCAssembler &Asm,
const SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap,
uint32_t GroupSymbolIndex,
uint64_t Offset, uint64_t Size, uint64_t Alignment,
const MCSectionELF &Section);
@@ -325,8 +326,7 @@ void SymbolTableWriter::createSymtabShndx() {
MCContext &Ctx = Asm.getContext();
const MCSectionELF *SymtabShndxSection =
- Ctx.getELFSection(".symtab_shndxr", ELF::SHT_SYMTAB_SHNDX, 0,
- SectionKind::getReadOnly(), 4, "");
+ Ctx.getELFSection(".symtab_shndxr", ELF::SHT_SYMTAB_SHNDX, 0, 4, "");
MCSectionData *SymtabShndxSD =
&Asm.getOrCreateSectionData(*SymtabShndxSection);
SymtabShndxSD->setAlignment(4);
@@ -789,13 +789,11 @@ static const MCSymbol *getWeakRef(const MCSymbolRefExpr &Ref) {
return nullptr;
}
-void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
+void ELFObjectWriter::RecordRelocation(MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
- const MCFixup &Fixup,
- MCValue Target,
- bool &IsPCRel,
- uint64_t &FixedValue) {
+ const MCFixup &Fixup, MCValue Target,
+ bool &IsPCRel, uint64_t &FixedValue) {
const MCSectionData *FixupSection = Fragment->getParent();
uint64_t C = Target.getConstant();
uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
@@ -946,9 +944,9 @@ bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isUsedInReloc) {
return true;
}
-void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
+void ELFObjectWriter::computeIndexMap(MCAssembler &Asm,
SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap) {
+ RelMapTy &RelMap) {
unsigned Index = 1;
for (MCAssembler::iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it) {
@@ -961,16 +959,20 @@ void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
for (MCAssembler::iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it) {
+ const MCSectionData &SD = *it;
const MCSectionELF &Section =
- static_cast<const MCSectionELF &>(it->getSection());
+ static_cast<const MCSectionELF &>(SD.getSection());
if (Section.getType() == ELF::SHT_GROUP ||
Section.getType() == ELF::SHT_REL ||
Section.getType() == ELF::SHT_RELA)
continue;
SectionIndexMap[&Section] = Index++;
- const MCSectionELF *RelSection = RelMap.lookup(&Section);
- if (RelSection)
+ if (MCSectionData *RelSD = createRelocationSection(Asm, SD)) {
+ const MCSectionELF *RelSection =
+ static_cast<const MCSectionELF *>(&RelSD->getSection());
+ RelMap[RelSection] = &Section;
SectionIndexMap[RelSection] = Index++;
+ }
}
}
@@ -1035,16 +1037,43 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
assert(MSD.SectionIndex && "Invalid section index!");
}
- // The @@@ in symbol version is replaced with @ in undefined symbols and
- // @@ in defined ones.
+ // The @@@ in symbol version is replaced with @ in undefined symbols and @@
+ // in defined ones.
+ //
+ // FIXME: All name handling should be done before we get to the writer,
+ // including dealing with GNU-style version suffixes. Fixing this isn't
+ // trivial.
+ //
+ // We thus have to be careful to not perform the symbol version replacement
+ // blindly:
+ //
+ // The ELF format is used on Windows by the MCJIT engine. Thus, on
+ // Windows, the ELFObjectWriter can encounter symbols mangled using the MS
+ // Visual Studio C++ name mangling scheme. Symbols mangled using the MSVC
+ // C++ name mangling can legally have "@@@" as a sub-string. In that case,
+ // the EFLObjectWriter should not interpret the "@@@" sub-string as
+ // specifying GNU-style symbol versioning. The ELFObjectWriter therefore
+ // checks for the MSVC C++ name mangling prefix which is either "?", "@?",
+ // "__imp_?" or "__imp_@?".
+ //
+ // It would have been interesting to perform the MS mangling prefix check
+ // only when the target triple is of the form *-pc-windows-elf. But, it
+ // seems that this information is not easily accessible from the
+ // ELFObjectWriter.
StringRef Name = Symbol.getName();
- SmallString<32> Buf;
- size_t Pos = Name.find("@@@");
- if (Pos != StringRef::npos) {
- Buf += Name.substr(0, Pos);
- unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
- Buf += Name.substr(Pos + Skip);
- Name = Buf;
+ if (!Name.startswith("?") && !Name.startswith("@?") &&
+ !Name.startswith("__imp_?") && !Name.startswith("__imp_@?")) {
+ // This symbol isn't following the MSVC C++ name mangling convention. We
+ // can thus safely interpret the @@@ in symbol names as specifying symbol
+ // versioning.
+ SmallString<32> Buf;
+ size_t Pos = Name.find("@@@");
+ if (Pos != StringRef::npos) {
+ Buf += Name.substr(0, Pos);
+ unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
+ Buf += Name.substr(Pos + Skip);
+ Name = Buf;
+ }
}
// Sections have their own string table
@@ -1093,44 +1122,37 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
UndefinedSymbolData[i].SymbolData->setIndex(Index++);
}
-void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm,
- MCAsmLayout &Layout,
- RelMapTy &RelMap) {
- for (MCAssembler::const_iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it) {
- const MCSectionData &SD = *it;
- if (Relocations[&SD].empty())
- continue;
-
- MCContext &Ctx = Asm.getContext();
- const MCSectionELF &Section =
- static_cast<const MCSectionELF&>(SD.getSection());
+MCSectionData *
+ELFObjectWriter::createRelocationSection(MCAssembler &Asm,
+ const MCSectionData &SD) {
+ if (Relocations[&SD].empty())
+ return nullptr;
- const StringRef SectionName = Section.getSectionName();
- std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel";
- RelaSectionName += SectionName;
+ MCContext &Ctx = Asm.getContext();
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(SD.getSection());
- unsigned EntrySize;
- if (hasRelocationAddend())
- EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
- else
- EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
+ const StringRef SectionName = Section.getSectionName();
+ std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel";
+ RelaSectionName += SectionName;
- unsigned Flags = 0;
- StringRef Group = "";
- if (Section.getFlags() & ELF::SHF_GROUP) {
- Flags = ELF::SHF_GROUP;
- Group = Section.getGroup()->getName();
- }
+ unsigned EntrySize;
+ if (hasRelocationAddend())
+ EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
+ else
+ EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
- const MCSectionELF *RelaSection =
- Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ?
- ELF::SHT_RELA : ELF::SHT_REL, Flags,
- SectionKind::getReadOnly(),
- EntrySize, Group);
- RelMap[&Section] = RelaSection;
- Asm.getOrCreateSectionData(*RelaSection);
+ unsigned Flags = 0;
+ StringRef Group = "";
+ if (Section.getFlags() & ELF::SHF_GROUP) {
+ Flags = ELF::SHF_GROUP;
+ Group = Section.getGroup()->getName();
}
+
+ const MCSectionELF *RelaSection = Ctx.getELFSection(
+ RelaSectionName, hasRelocationAddend() ? ELF::SHT_RELA : ELF::SHT_REL,
+ Flags, EntrySize, Group, true);
+ return &Asm.getOrCreateSectionData(*RelaSection);
}
static SmallVector<char, 128>
@@ -1280,20 +1302,21 @@ void ELFObjectWriter::CompressDebugSections(MCAssembler &Asm,
void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
const RelMapTy &RelMap) {
- for (MCAssembler::const_iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it) {
- const MCSectionData &SD = *it;
- const MCSectionELF &Section =
- static_cast<const MCSectionELF&>(SD.getSection());
+ for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) {
+ MCSectionData &RelSD = *it;
+ const MCSectionELF &RelSection =
+ static_cast<const MCSectionELF &>(RelSD.getSection());
- const MCSectionELF *RelaSection = RelMap.lookup(&Section);
- if (!RelaSection)
+ unsigned Type = RelSection.getType();
+ if (Type != ELF::SHT_REL && Type != ELF::SHT_RELA)
continue;
- MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
- RelaSD.setAlignment(is64Bit() ? 8 : 4);
- MCDataFragment *F = new MCDataFragment(&RelaSD);
- WriteRelocationsFragment(Asm, F, &*it);
+ const MCSectionELF *Section = RelMap.lookup(&RelSection);
+ MCSectionData &SD = Asm.getOrCreateSectionData(*Section);
+ RelSD.setAlignment(is64Bit() ? 8 : 4);
+
+ MCDataFragment *F = new MCDataFragment(&RelSD);
+ WriteRelocationsFragment(Asm, F, &SD);
}
}
@@ -1374,10 +1397,8 @@ void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
}
}
-void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
- MCAsmLayout &Layout,
- SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap) {
+void ELFObjectWriter::CreateMetadataSections(
+ MCAssembler &Asm, MCAsmLayout &Layout, SectionIndexMapTy &SectionIndexMap) {
MCContext &Ctx = Asm.getContext();
MCDataFragment *F;
@@ -1385,29 +1406,26 @@ void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
// We construct .shstrtab, .symtab and .strtab in this order to match gnu as.
const MCSectionELF *ShstrtabSection =
- Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
- SectionKind::getReadOnly());
+ Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0);
MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
ShstrtabSD.setAlignment(1);
+ ShstrtabIndex = SectionIndexMap.size() + 1;
+ SectionIndexMap[ShstrtabSection] = ShstrtabIndex;
const MCSectionELF *SymtabSection =
Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
- SectionKind::getReadOnly(),
EntrySize, "");
MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
SymtabSD.setAlignment(is64Bit() ? 8 : 4);
+ SymbolTableIndex = SectionIndexMap.size() + 1;
+ SectionIndexMap[SymtabSection] = SymbolTableIndex;
const MCSectionELF *StrtabSection;
- StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
- SectionKind::getReadOnly());
+ StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0);
MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
StrtabSD.setAlignment(1);
-
- ComputeIndexMap(Asm, SectionIndexMap, RelMap);
-
- ShstrtabIndex = SectionIndexMap.lookup(ShstrtabSection);
- SymbolTableIndex = SectionIndexMap.lookup(SymtabSection);
- StringTableIndex = SectionIndexMap.lookup(StrtabSection);
+ StringTableIndex = SectionIndexMap.size() + 1;
+ SectionIndexMap[StrtabSection] = StringTableIndex;
// Symbol table
F = new MCDataFragment(&SymtabSD);
@@ -1430,12 +1448,12 @@ void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
ShStrTabBuilder.data().end());
}
-void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
+void ELFObjectWriter::createIndexedSections(MCAssembler &Asm,
MCAsmLayout &Layout,
GroupMapTy &GroupMap,
RevGroupMapTy &RevGroupMap,
SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap) {
+ RelMapTy &RelMap) {
MCContext &Ctx = Asm.getContext();
// Build the groups
@@ -1459,7 +1477,7 @@ void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
GroupMap[Group] = SignatureSymbol;
}
- ComputeIndexMap(Asm, SectionIndexMap, RelMap);
+ computeIndexMap(Asm, SectionIndexMap, RelMap);
// Add sections to the groups
for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
@@ -1477,8 +1495,9 @@ void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
}
}
-void ELFObjectWriter::WriteSection(MCAssembler &Asm,
+void ELFObjectWriter::writeSection(MCAssembler &Asm,
const SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap,
uint32_t GroupSymbolIndex,
uint64_t Offset, uint64_t Size,
uint64_t Alignment,
@@ -1494,23 +1513,9 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm,
case ELF::SHT_REL:
case ELF::SHT_RELA: {
- const MCSectionELF *SymtabSection;
- const MCSectionELF *InfoSection;
- SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB,
- 0,
- SectionKind::getReadOnly());
- sh_link = SectionIndexMap.lookup(SymtabSection);
+ sh_link = SymbolTableIndex;
assert(sh_link && ".symtab not found");
-
- // Remove ".rel" and ".rela" prefixes.
- unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
- StringRef SectionName = Section.getSectionName().substr(SecNameLen);
- StringRef GroupName =
- Section.getGroup() ? Section.getGroup()->getName() : "";
-
- InfoSection = Asm.getContext().getELFSection(SectionName, ELF::SHT_PROGBITS,
- 0, SectionKind::getReadOnly(),
- 0, GroupName);
+ const MCSectionELF *InfoSection = RelMap.find(&Section)->second;
sh_info = SectionIndexMap.lookup(InfoSection);
break;
}
@@ -1554,18 +1559,14 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm,
Section.getType() == ELF::SHT_ARM_EXIDX) {
StringRef SecName(Section.getSectionName());
if (SecName == ".ARM.exidx") {
- sh_link = SectionIndexMap.lookup(
- Asm.getContext().getELFSection(".text",
- ELF::SHT_PROGBITS,
- ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
- SectionKind::getText()));
+ sh_link = SectionIndexMap.lookup(Asm.getContext().getELFSection(
+ ".text", ELF::SHT_PROGBITS, ELF::SHF_EXECINSTR | ELF::SHF_ALLOC));
} else if (SecName.startswith(".ARM.exidx")) {
StringRef GroupName =
Section.getGroup() ? Section.getGroup()->getName() : "";
sh_link = SectionIndexMap.lookup(Asm.getContext().getELFSection(
SecName.substr(sizeof(".ARM.exidx") - 1), ELF::SHT_PROGBITS,
- ELF::SHF_EXECINSTR | ELF::SHF_ALLOC, SectionKind::getText(), 0,
- GroupName));
+ ELF::SHF_EXECINSTR | ELF::SHF_ALLOC, 0, GroupName));
}
}
@@ -1625,11 +1626,10 @@ void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm,
}
}
-void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm,
- const GroupMapTy &GroupMap,
- const MCAsmLayout &Layout,
- const SectionIndexMapTy &SectionIndexMap,
- const SectionOffsetMapTy &SectionOffsetMap) {
+void ELFObjectWriter::writeSectionHeader(
+ MCAssembler &Asm, const GroupMapTy &GroupMap, const MCAsmLayout &Layout,
+ const SectionIndexMapTy &SectionIndexMap, const RelMapTy &RelMap,
+ const SectionOffsetMapTy &SectionOffsetMap) {
const unsigned NumSections = Asm.size() + 1;
std::vector<const MCSectionELF*> Sections;
@@ -1660,7 +1660,7 @@ void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm,
uint64_t Size = GetSectionAddressSize(Layout, SD);
- WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
+ writeSection(Asm, SectionIndexMap, RelMap, GroupSymbolIndex,
SectionOffsetMap.lookup(&Section), Size,
SD.getAlignment(), Section);
}
@@ -1707,10 +1707,8 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
CompressDebugSections(Asm, const_cast<MCAsmLayout &>(Layout));
DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap;
- CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
-
const unsigned NumUserAndRelocSections = Asm.size();
- CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
+ createIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
RevGroupMap, SectionIndexMap, RelMap);
const unsigned AllSections = Asm.size();
const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections;
@@ -1725,8 +1723,7 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
CreateMetadataSections(const_cast<MCAssembler&>(Asm),
const_cast<MCAsmLayout&>(Layout),
- SectionIndexMap,
- RelMap);
+ SectionIndexMap);
uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
@@ -1783,7 +1780,7 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm,
WriteZeros(Padding);
// ... then the section header table ...
- WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap,
+ writeSectionHeader(Asm, GroupMap, Layout, SectionIndexMap, RelMap,
SectionOffsetMap);
// ... and then the remaining sections ...
generated by cgit v1.1 at 2024-12-22 11:21:43 +0000