DwarfCFIEHPrinter.h
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//===--- DwarfCFIEHPrinter.h - DWARF-based Unwind Information Printer -----===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_READOBJ_DWARFCFIEHPRINTER_H
#define LLVM_TOOLS_LLVM_READOBJ_DWARFCFIEHPRINTER_H
#include "llvm-readobj.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugFrame.h"
#include "llvm/Object/ELF.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/ELFTypes.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/ScopedPrinter.h"
#include "llvm/Support/type_traits.h"
namespace llvm {
namespace DwarfCFIEH {
template <typename ELFT> class PrinterContext {
using Elf_Shdr = typename ELFT::Shdr;
using Elf_Phdr = typename ELFT::Phdr;
ScopedPrinter &W;
const object::ELFObjectFile<ELFT> &ObjF;
void printEHFrameHdr(const Elf_Phdr *EHFramePHdr) const;
void printEHFrame(const Elf_Shdr *EHFrameShdr) const;
public:
PrinterContext(ScopedPrinter &W, const object::ELFObjectFile<ELFT> &ObjF)
: W(W), ObjF(ObjF) {}
void printUnwindInformation() const;
};
template <class ELFT>
static const typename ELFT::Shdr *
findSectionByAddress(const object::ELFObjectFile<ELFT> &ObjF, uint64_t Addr) {
Expected<typename ELFT::ShdrRange> SectionsOrErr =
ObjF.getELFFile()->sections();
if (!SectionsOrErr)
reportError(SectionsOrErr.takeError(), ObjF.getFileName());
for (const typename ELFT::Shdr &Shdr : *SectionsOrErr)
if (Shdr.sh_addr == Addr)
return &Shdr;
return nullptr;
}
template <typename ELFT>
void PrinterContext<ELFT>::printUnwindInformation() const {
const object::ELFFile<ELFT> &Obj = *ObjF.getELFFile();
Expected<typename ELFT::PhdrRange> PhdrsOrErr = Obj.program_headers();
if (!PhdrsOrErr)
reportError(PhdrsOrErr.takeError(), ObjF.getFileName());
for (const Elf_Phdr &Phdr : *PhdrsOrErr) {
if (Phdr.p_type != ELF::PT_GNU_EH_FRAME)
continue;
if (Phdr.p_memsz != Phdr.p_filesz)
reportError(object::createError(
"p_memsz does not match p_filesz for GNU_EH_FRAME"),
ObjF.getFileName());
printEHFrameHdr(&Phdr);
break;
}
Expected<typename ELFT::ShdrRange> SectionsOrErr = Obj.sections();
if (!SectionsOrErr)
reportError(SectionsOrErr.takeError(), ObjF.getFileName());
for (const Elf_Shdr &Shdr : *SectionsOrErr) {
Expected<StringRef> NameOrErr = Obj.getSectionName(Shdr);
if (!NameOrErr)
reportError(NameOrErr.takeError(), ObjF.getFileName());
if (*NameOrErr == ".eh_frame")
printEHFrame(&Shdr);
}
}
template <typename ELFT>
void PrinterContext<ELFT>::printEHFrameHdr(const Elf_Phdr *EHFramePHdr) const {
DictScope L(W, "EHFrameHeader");
uint64_t EHFrameHdrAddress = EHFramePHdr->p_vaddr;
W.startLine() << format("Address: 0x%" PRIx64 "\n", EHFrameHdrAddress);
W.startLine() << format("Offset: 0x%" PRIx64 "\n", (uint64_t)EHFramePHdr->p_offset);
W.startLine() << format("Size: 0x%" PRIx64 "\n", (uint64_t)EHFramePHdr->p_memsz);
const object::ELFFile<ELFT> &Obj = *ObjF.getELFFile();
if (const Elf_Shdr *EHFrameHdr =
findSectionByAddress(ObjF, EHFramePHdr->p_vaddr)) {
Expected<StringRef> NameOrErr = Obj.getSectionName(*EHFrameHdr);
if (!NameOrErr)
reportError(NameOrErr.takeError(), ObjF.getFileName());
W.printString("Corresponding Section", *NameOrErr);
}
Expected<ArrayRef<uint8_t>> Content = Obj.getSegmentContents(*EHFramePHdr);
if (!Content)
reportError(Content.takeError(), ObjF.getFileName());
DataExtractor DE(*Content,
ELFT::TargetEndianness == support::endianness::little,
ELFT::Is64Bits ? 8 : 4);
DictScope D(W, "Header");
uint64_t Offset = 0;
auto Version = DE.getU8(&Offset);
W.printNumber("version", Version);
if (Version != 1)
reportError(
object::createError("only version 1 of .eh_frame_hdr is supported"),
ObjF.getFileName());
uint64_t EHFramePtrEnc = DE.getU8(&Offset);
W.startLine() << format("eh_frame_ptr_enc: 0x%" PRIx64 "\n", EHFramePtrEnc);
if (EHFramePtrEnc != (dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4))
reportError(object::createError("unexpected encoding eh_frame_ptr_enc"),
ObjF.getFileName());
uint64_t FDECountEnc = DE.getU8(&Offset);
W.startLine() << format("fde_count_enc: 0x%" PRIx64 "\n", FDECountEnc);
if (FDECountEnc != dwarf::DW_EH_PE_udata4)
reportError(object::createError("unexpected encoding fde_count_enc"),
ObjF.getFileName());
uint64_t TableEnc = DE.getU8(&Offset);
W.startLine() << format("table_enc: 0x%" PRIx64 "\n", TableEnc);
if (TableEnc != (dwarf::DW_EH_PE_datarel | dwarf::DW_EH_PE_sdata4))
reportError(object::createError("unexpected encoding table_enc"),
ObjF.getFileName());
auto EHFramePtr = DE.getSigned(&Offset, 4) + EHFrameHdrAddress + 4;
W.startLine() << format("eh_frame_ptr: 0x%" PRIx64 "\n", EHFramePtr);
auto FDECount = DE.getUnsigned(&Offset, 4);
W.printNumber("fde_count", FDECount);
unsigned NumEntries = 0;
uint64_t PrevPC = 0;
while (Offset + 8 <= EHFramePHdr->p_memsz && NumEntries < FDECount) {
DictScope D(W, std::string("entry ") + std::to_string(NumEntries));
auto InitialPC = DE.getSigned(&Offset, 4) + EHFrameHdrAddress;
W.startLine() << format("initial_location: 0x%" PRIx64 "\n", InitialPC);
auto Address = DE.getSigned(&Offset, 4) + EHFrameHdrAddress;
W.startLine() << format("address: 0x%" PRIx64 "\n", Address);
if (InitialPC < PrevPC)
reportError(object::createError("initial_location is out of order"),
ObjF.getFileName());
PrevPC = InitialPC;
++NumEntries;
}
}
template <typename ELFT>
void PrinterContext<ELFT>::printEHFrame(const Elf_Shdr *EHFrameShdr) const {
uint64_t Address = EHFrameShdr->sh_addr;
uint64_t ShOffset = EHFrameShdr->sh_offset;
W.startLine() << format(".eh_frame section at offset 0x%" PRIx64
" address 0x%" PRIx64 ":\n",
ShOffset, Address);
W.indent();
Expected<ArrayRef<uint8_t>> DataOrErr =
ObjF.getELFFile()->getSectionContents(*EHFrameShdr);
if (!DataOrErr)
reportError(DataOrErr.takeError(), ObjF.getFileName());
// Construct DWARFDataExtractor to handle relocations ("PC Begin" fields).
std::unique_ptr<DWARFContext> DICtx = DWARFContext::create(ObjF, nullptr);
DWARFDataExtractor DE(DICtx->getDWARFObj(),
DICtx->getDWARFObj().getEHFrameSection(),
ELFT::TargetEndianness == support::endianness::little,
ELFT::Is64Bits ? 8 : 4);
DWARFDebugFrame EHFrame(Triple::ArchType(ObjF.getArch()), /*IsEH=*/true,
/*EHFrameAddress=*/Address);
if (Error E = EHFrame.parse(DE))
reportError(std::move(E), ObjF.getFileName());
for (const dwarf::FrameEntry &Entry : EHFrame) {
if (const dwarf::CIE *CIE = dyn_cast<dwarf::CIE>(&Entry)) {
W.startLine() << format("[0x%" PRIx64 "] CIE length=%" PRIu64 "\n",
Address + CIE->getOffset(), CIE->getLength());
W.indent();
W.printNumber("version", CIE->getVersion());
W.printString("augmentation", CIE->getAugmentationString());
W.printNumber("code_alignment_factor", CIE->getCodeAlignmentFactor());
W.printNumber("data_alignment_factor", CIE->getDataAlignmentFactor());
W.printNumber("return_address_register", CIE->getReturnAddressRegister());
} else {
const dwarf::FDE *FDE = cast<dwarf::FDE>(&Entry);
W.startLine() << format("[0x%" PRIx64 "] FDE length=%" PRIu64
" cie=[0x%" PRIx64 "]\n",
Address + FDE->getOffset(), FDE->getLength(),
Address + FDE->getLinkedCIE()->getOffset());
W.indent();
W.startLine() << format("initial_location: 0x%" PRIx64 "\n",
FDE->getInitialLocation());
W.startLine() << format(
"address_range: 0x%" PRIx64 " (end : 0x%" PRIx64 ")\n",
FDE->getAddressRange(),
FDE->getInitialLocation() + FDE->getAddressRange());
}
W.getOStream() << "\n";
W.startLine() << "Program:\n";
W.indent();
Entry.cfis().dump(W.getOStream(), nullptr, W.getIndentLevel());
W.unindent();
W.unindent();
W.getOStream() << "\n";
}
W.unindent();
}
} // namespace DwarfCFIEH
} // namespace llvm
#endif