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llvm-project/llvm/tools/llvm-objdump/ELFDump.cpp

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//===-- ELFDump.cpp - ELF-specific dumper -----------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements the ELF-specific dumper for llvm-objdump.
///
//===----------------------------------------------------------------------===//
#include "ELFDump.h"
#include "llvm-objdump.h"
#include "llvm/Demangle/Demangle.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::objdump;
template <class ELFT>
static Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> &Elf) {
auto DynamicEntriesOrError = Elf.dynamicEntries();
if (!DynamicEntriesOrError)
return DynamicEntriesOrError.takeError();
for (const typename ELFT::Dyn &Dyn : *DynamicEntriesOrError) {
if (Dyn.d_tag == ELF::DT_STRTAB) {
auto MappedAddrOrError = Elf.toMappedAddr(Dyn.getPtr());
if (!MappedAddrOrError)
consumeError(MappedAddrOrError.takeError());
return StringRef(reinterpret_cast<const char *>(*MappedAddrOrError));
}
}
// If the dynamic segment is not present, we fall back on the sections.
auto SectionsOrError = Elf.sections();
if (!SectionsOrError)
return SectionsOrError.takeError();
for (const typename ELFT::Shdr &Sec : *SectionsOrError) {
if (Sec.sh_type == ELF::SHT_DYNSYM)
return Elf.getStringTableForSymtab(Sec);
}
return createError("dynamic string table not found");
}
template <class ELFT>
static Error getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
const RelocationRef &RelRef,
SmallVectorImpl<char> &Result) {
const ELFFile<ELFT> &EF = Obj->getELFFile();
DataRefImpl Rel = RelRef.getRawDataRefImpl();
auto SecOrErr = EF.getSection(Rel.d.a);
if (!SecOrErr)
return SecOrErr.takeError();
int64_t Addend = 0;
// If there is no Symbol associated with the relocation, we set the undef
// boolean value to 'true'. This will prevent us from calling functions that
// requires the relocation to be associated with a symbol.
//
// In SHT_REL case we would need to read the addend from section data.
// GNU objdump does not do that and we just follow for simplicity atm.
bool Undef = false;
if ((*SecOrErr)->sh_type == ELF::SHT_RELA) {
const typename ELFT::Rela *ERela = Obj->getRela(Rel);
Addend = ERela->r_addend;
Undef = ERela->getSymbol(false) == 0;
} else if ((*SecOrErr)->sh_type != ELF::SHT_REL) {
return make_error<BinaryError>();
}
// Default scheme is to print Target, as well as "+ <addend>" for nonzero
// addend. Should be acceptable for all normal purposes.
std::string FmtBuf;
raw_string_ostream Fmt(FmtBuf);
if (!Undef) {
symbol_iterator SI = RelRef.getSymbol();
Expected<const typename ELFT::Sym *> SymOrErr =
Obj->getSymbol(SI->getRawDataRefImpl());
// TODO: test this error.
if (!SymOrErr)
return SymOrErr.takeError();
if ((*SymOrErr)->getType() == ELF::STT_SECTION) {
Expected<section_iterator> SymSI = SI->getSection();
if (!SymSI)
return SymSI.takeError();
const typename ELFT::Shdr *SymSec =
Obj->getSection((*SymSI)->getRawDataRefImpl());
auto SecName = EF.getSectionName(*SymSec);
if (!SecName)
return SecName.takeError();
Fmt << *SecName;
} else {
Expected<StringRef> SymName = SI->getName();
if (!SymName)
return SymName.takeError();
if (Demangle)
Fmt << demangle(std::string(*SymName));
else
Fmt << *SymName;
}
} else {
Fmt << "*ABS*";
}
if (Addend != 0) {
Fmt << (Addend < 0
? "-"
: "+") << format("0x%" PRIx64,
(Addend < 0 ? -(uint64_t)Addend : (uint64_t)Addend));
}
Fmt.flush();
Result.append(FmtBuf.begin(), FmtBuf.end());
return Error::success();
}
Error objdump::getELFRelocationValueString(const ELFObjectFileBase *Obj,
const RelocationRef &Rel,
SmallVectorImpl<char> &Result) {
if (auto *ELF32LE = dyn_cast<ELF32LEObjectFile>(Obj))
return getRelocationValueString(ELF32LE, Rel, Result);
if (auto *ELF64LE = dyn_cast<ELF64LEObjectFile>(Obj))
return getRelocationValueString(ELF64LE, Rel, Result);
if (auto *ELF32BE = dyn_cast<ELF32BEObjectFile>(Obj))
return getRelocationValueString(ELF32BE, Rel, Result);
auto *ELF64BE = cast<ELF64BEObjectFile>(Obj);
return getRelocationValueString(ELF64BE, Rel, Result);
}
template <class ELFT>
static uint64_t getSectionLMA(const ELFFile<ELFT> &Obj,
const object::ELFSectionRef &Sec) {
auto PhdrRangeOrErr = Obj.program_headers();
if (!PhdrRangeOrErr)
report_fatal_error(toString(PhdrRangeOrErr.takeError()));
// Search for a PT_LOAD segment containing the requested section. Use this
// segment's p_addr to calculate the section's LMA.
for (const typename ELFT::Phdr &Phdr : *PhdrRangeOrErr)
if ((Phdr.p_type == ELF::PT_LOAD) && (Phdr.p_vaddr <= Sec.getAddress()) &&
(Phdr.p_vaddr + Phdr.p_memsz > Sec.getAddress()))
return Sec.getAddress() - Phdr.p_vaddr + Phdr.p_paddr;
// Return section's VMA if it isn't in a PT_LOAD segment.
return Sec.getAddress();
}
uint64_t objdump::getELFSectionLMA(const object::ELFSectionRef &Sec) {
if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Sec.getObject()))
return getSectionLMA(ELFObj->getELFFile(), Sec);
else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Sec.getObject()))
return getSectionLMA(ELFObj->getELFFile(), Sec);
else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Sec.getObject()))
return getSectionLMA(ELFObj->getELFFile(), Sec);
const auto *ELFObj = cast<ELF64BEObjectFile>(Sec.getObject());
return getSectionLMA(ELFObj->getELFFile(), Sec);
}
template <class ELFT>
static void printDynamicSection(const ELFFile<ELFT> &Elf, StringRef Filename) {
ArrayRef<typename ELFT::Dyn> DynamicEntries =
unwrapOrError(Elf.dynamicEntries(), Filename);
// Find the maximum tag name length to format the value column properly.
size_t MaxLen = 0;
for (const typename ELFT::Dyn &Dyn : DynamicEntries)
MaxLen = std::max(MaxLen, Elf.getDynamicTagAsString(Dyn.d_tag).size());
std::string TagFmt = " %-" + std::to_string(MaxLen) + "s ";
outs() << "Dynamic Section:\n";
for (const typename ELFT::Dyn &Dyn : DynamicEntries) {
if (Dyn.d_tag == ELF::DT_NULL)
continue;
std::string Str = Elf.getDynamicTagAsString(Dyn.d_tag);
outs() << format(TagFmt.c_str(), Str.c_str());
const char *Fmt =
ELFT::Is64Bits ? "0x%016" PRIx64 "\n" : "0x%08" PRIx64 "\n";
if (Dyn.d_tag == ELF::DT_NEEDED || Dyn.d_tag == ELF::DT_RPATH ||
Dyn.d_tag == ELF::DT_RUNPATH || Dyn.d_tag == ELF::DT_SONAME ||
Dyn.d_tag == ELF::DT_AUXILIARY || Dyn.d_tag == ELF::DT_FILTER) {
Expected<StringRef> StrTabOrErr = getDynamicStrTab(Elf);
if (StrTabOrErr) {
const char *Data = StrTabOrErr.get().data();
outs() << (Data + Dyn.d_un.d_val) << "\n";
continue;
}
reportWarning(toString(StrTabOrErr.takeError()), Filename);
consumeError(StrTabOrErr.takeError());
}
outs() << format(Fmt, (uint64_t)Dyn.d_un.d_val);
}
}
template <class ELFT>
static void printProgramHeaders(const ELFFile<ELFT> &Obj, StringRef FileName) {
outs() << "Program Header:\n";
auto ProgramHeaderOrError = Obj.program_headers();
if (!ProgramHeaderOrError) {
reportWarning("unable to read program headers: " +
toString(ProgramHeaderOrError.takeError()),
FileName);
return;
}
for (const typename ELFT::Phdr &Phdr : *ProgramHeaderOrError) {
switch (Phdr.p_type) {
case ELF::PT_DYNAMIC:
outs() << " DYNAMIC ";
break;
case ELF::PT_GNU_EH_FRAME:
outs() << "EH_FRAME ";
break;
case ELF::PT_GNU_RELRO:
outs() << " RELRO ";
break;
case ELF::PT_GNU_PROPERTY:
outs() << " PROPERTY ";
break;
case ELF::PT_GNU_STACK:
outs() << " STACK ";
break;
case ELF::PT_INTERP:
outs() << " INTERP ";
break;
case ELF::PT_LOAD:
outs() << " LOAD ";
break;
case ELF::PT_NOTE:
outs() << " NOTE ";
break;
case ELF::PT_OPENBSD_BOOTDATA:
outs() << " OPENBSD_BOOTDATA ";
break;
case ELF::PT_OPENBSD_RANDOMIZE:
outs() << " OPENBSD_RANDOMIZE ";
break;
case ELF::PT_OPENBSD_WXNEEDED:
outs() << " OPENBSD_WXNEEDED ";
break;
case ELF::PT_PHDR:
outs() << " PHDR ";
break;
case ELF::PT_TLS:
outs() << " TLS ";
break;
default:
outs() << " UNKNOWN ";
}
const char *Fmt = ELFT::Is64Bits ? "0x%016" PRIx64 " " : "0x%08" PRIx64 " ";
outs() << "off " << format(Fmt, (uint64_t)Phdr.p_offset) << "vaddr "
<< format(Fmt, (uint64_t)Phdr.p_vaddr) << "paddr "
<< format(Fmt, (uint64_t)Phdr.p_paddr)
<< format("align 2**%u\n",
countTrailingZeros<uint64_t>(Phdr.p_align))
<< " filesz " << format(Fmt, (uint64_t)Phdr.p_filesz)
<< "memsz " << format(Fmt, (uint64_t)Phdr.p_memsz) << "flags "
<< ((Phdr.p_flags & ELF::PF_R) ? "r" : "-")
<< ((Phdr.p_flags & ELF::PF_W) ? "w" : "-")
<< ((Phdr.p_flags & ELF::PF_X) ? "x" : "-") << "\n";
}
outs() << "\n";
}
template <class ELFT>
static void printSymbolVersionDependency(ArrayRef<uint8_t> Contents,
StringRef StrTab) {
outs() << "Version References:\n";
const uint8_t *Buf = Contents.data();
while (Buf) {
auto *Verneed = reinterpret_cast<const typename ELFT::Verneed *>(Buf);
outs() << " required from "
<< StringRef(StrTab.drop_front(Verneed->vn_file).data()) << ":\n";
const uint8_t *BufAux = Buf + Verneed->vn_aux;
while (BufAux) {
auto *Vernaux = reinterpret_cast<const typename ELFT::Vernaux *>(BufAux);
outs() << " "
<< format("0x%08" PRIx32 " ", (uint32_t)Vernaux->vna_hash)
<< format("0x%02" PRIx16 " ", (uint16_t)Vernaux->vna_flags)
<< format("%02" PRIu16 " ", (uint16_t)Vernaux->vna_other)
<< StringRef(StrTab.drop_front(Vernaux->vna_name).data()) << '\n';
BufAux = Vernaux->vna_next ? BufAux + Vernaux->vna_next : nullptr;
}
Buf = Verneed->vn_next ? Buf + Verneed->vn_next : nullptr;
}
}
template <class ELFT>
static void printSymbolVersionDefinition(const typename ELFT::Shdr &Shdr,
ArrayRef<uint8_t> Contents,
StringRef StrTab) {
outs() << "Version definitions:\n";
const uint8_t *Buf = Contents.data();
uint32_t VerdefIndex = 1;
// sh_info contains the number of entries in the SHT_GNU_verdef section. To
// make the index column have consistent width, we should insert blank spaces
// according to sh_info.
uint16_t VerdefIndexWidth = std::to_string(Shdr.sh_info).size();
while (Buf) {
auto *Verdef = reinterpret_cast<const typename ELFT::Verdef *>(Buf);
outs() << format_decimal(VerdefIndex++, VerdefIndexWidth) << " "
<< format("0x%02" PRIx16 " ", (uint16_t)Verdef->vd_flags)
<< format("0x%08" PRIx32 " ", (uint32_t)Verdef->vd_hash);
const uint8_t *BufAux = Buf + Verdef->vd_aux;
uint16_t VerdauxIndex = 0;
while (BufAux) {
auto *Verdaux = reinterpret_cast<const typename ELFT::Verdaux *>(BufAux);
if (VerdauxIndex)
outs() << std::string(VerdefIndexWidth + 17, ' ');
outs() << StringRef(StrTab.drop_front(Verdaux->vda_name).data()) << '\n';
BufAux = Verdaux->vda_next ? BufAux + Verdaux->vda_next : nullptr;
++VerdauxIndex;
}
Buf = Verdef->vd_next ? Buf + Verdef->vd_next : nullptr;
}
}
template <class ELFT>
static void printSymbolVersionInfo(const ELFFile<ELFT> &Elf,
StringRef FileName) {
ArrayRef<typename ELFT::Shdr> Sections =
unwrapOrError(Elf.sections(), FileName);
for (const typename ELFT::Shdr &Shdr : Sections) {
if (Shdr.sh_type != ELF::SHT_GNU_verneed &&
Shdr.sh_type != ELF::SHT_GNU_verdef)
continue;
ArrayRef<uint8_t> Contents =
unwrapOrError(Elf.getSectionContents(Shdr), FileName);
const typename ELFT::Shdr *StrTabSec =
unwrapOrError(Elf.getSection(Shdr.sh_link), FileName);
StringRef StrTab = unwrapOrError(Elf.getStringTable(*StrTabSec), FileName);
if (Shdr.sh_type == ELF::SHT_GNU_verneed)
printSymbolVersionDependency<ELFT>(Contents, StrTab);
else
printSymbolVersionDefinition<ELFT>(Shdr, Contents, StrTab);
}
}
void objdump::printELFFileHeader(const object::ObjectFile *Obj) {
if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName());
}
void objdump::printELFDynamicSection(const object::ObjectFile *Obj) {
if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
}
void objdump::printELFSymbolVersionInfo(const object::ObjectFile *Obj) {
if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
}
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