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llvm-mirror/tools/llvm-readobj/ARMEHABIPrinter.h
Georgii Rymar e57c84fe7d [llvm-readobj][ARM] - Improve support of printing unwind (-u) information for non-relocatable objects. 
This is the one more patch for https://bugs.llvm.org/show_bug.cgi?id=47581

It fixes how we print an information for the Generic model. With this patch
we are able to read values from `.ARM.extab` and dump proper personality routines names/addresses.

Differential revision: https://reviews.llvm.org/D88478
2020-09-30 11:43:34 +03:00

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//===--- ARMEHABIPrinter.h - ARM EHABI 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_ARMEHABIPRINTER_H
#define LLVM_TOOLS_LLVM_READOBJ_ARMEHABIPRINTER_H
#include "llvm-readobj.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Object/ELF.h"
#include "llvm/Object/ELFTypes.h"
#include "llvm/Support/ARMEHABI.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 ARM {
namespace EHABI {
class OpcodeDecoder {
ScopedPrinter &SW;
raw_ostream &OS;
struct RingEntry {
uint8_t Mask;
uint8_t Value;
void (OpcodeDecoder::*Routine)(const uint8_t *Opcodes, unsigned &OI);
};
static ArrayRef<RingEntry> ring();
void Decode_00xxxxxx(const uint8_t *Opcodes, unsigned &OI);
void Decode_01xxxxxx(const uint8_t *Opcodes, unsigned &OI);
void Decode_1000iiii_iiiiiiii(const uint8_t *Opcodes, unsigned &OI);
void Decode_10011101(const uint8_t *Opcodes, unsigned &OI);
void Decode_10011111(const uint8_t *Opcodes, unsigned &OI);
void Decode_1001nnnn(const uint8_t *Opcodes, unsigned &OI);
void Decode_10100nnn(const uint8_t *Opcodes, unsigned &OI);
void Decode_10101nnn(const uint8_t *Opcodes, unsigned &OI);
void Decode_10110000(const uint8_t *Opcodes, unsigned &OI);
void Decode_10110001_0000iiii(const uint8_t *Opcodes, unsigned &OI);
void Decode_10110010_uleb128(const uint8_t *Opcodes, unsigned &OI);
void Decode_10110011_sssscccc(const uint8_t *Opcodes, unsigned &OI);
void Decode_101101nn(const uint8_t *Opcodes, unsigned &OI);
void Decode_10111nnn(const uint8_t *Opcodes, unsigned &OI);
void Decode_11000110_sssscccc(const uint8_t *Opcodes, unsigned &OI);
void Decode_11000111_0000iiii(const uint8_t *Opcodes, unsigned &OI);
void Decode_11001000_sssscccc(const uint8_t *Opcodes, unsigned &OI);
void Decode_11001001_sssscccc(const uint8_t *Opcodes, unsigned &OI);
void Decode_11001yyy(const uint8_t *Opcodes, unsigned &OI);
void Decode_11000nnn(const uint8_t *Opcodes, unsigned &OI);
void Decode_11010nnn(const uint8_t *Opcodes, unsigned &OI);
void Decode_11xxxyyy(const uint8_t *Opcodes, unsigned &OI);
void PrintGPR(uint16_t GPRMask);
void PrintRegisters(uint32_t Mask, StringRef Prefix);
public:
OpcodeDecoder(ScopedPrinter &SW) : SW(SW), OS(SW.getOStream()) {}
void Decode(const uint8_t *Opcodes, off_t Offset, size_t Length);
};
inline ArrayRef<OpcodeDecoder::RingEntry> OpcodeDecoder::ring() {
static const OpcodeDecoder::RingEntry Ring[] = {
{0xc0, 0x00, &OpcodeDecoder::Decode_00xxxxxx},
{0xc0, 0x40, &OpcodeDecoder::Decode_01xxxxxx},
{0xf0, 0x80, &OpcodeDecoder::Decode_1000iiii_iiiiiiii},
{0xff, 0x9d, &OpcodeDecoder::Decode_10011101},
{0xff, 0x9f, &OpcodeDecoder::Decode_10011111},
{0xf0, 0x90, &OpcodeDecoder::Decode_1001nnnn},
{0xf8, 0xa0, &OpcodeDecoder::Decode_10100nnn},
{0xf8, 0xa8, &OpcodeDecoder::Decode_10101nnn},
{0xff, 0xb0, &OpcodeDecoder::Decode_10110000},
{0xff, 0xb1, &OpcodeDecoder::Decode_10110001_0000iiii},
{0xff, 0xb2, &OpcodeDecoder::Decode_10110010_uleb128},
{0xff, 0xb3, &OpcodeDecoder::Decode_10110011_sssscccc},
{0xfc, 0xb4, &OpcodeDecoder::Decode_101101nn},
{0xf8, 0xb8, &OpcodeDecoder::Decode_10111nnn},
{0xff, 0xc6, &OpcodeDecoder::Decode_11000110_sssscccc},
{0xff, 0xc7, &OpcodeDecoder::Decode_11000111_0000iiii},
{0xff, 0xc8, &OpcodeDecoder::Decode_11001000_sssscccc},
{0xff, 0xc9, &OpcodeDecoder::Decode_11001001_sssscccc},
{0xc8, 0xc8, &OpcodeDecoder::Decode_11001yyy},
{0xf8, 0xc0, &OpcodeDecoder::Decode_11000nnn},
{0xf8, 0xd0, &OpcodeDecoder::Decode_11010nnn},
{0xc0, 0xc0, &OpcodeDecoder::Decode_11xxxyyy},
};
return makeArrayRef(Ring);
}
inline void OpcodeDecoder::Decode_00xxxxxx(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; vsp = vsp + %u\n", Opcode,
((Opcode & 0x3f) << 2) + 4);
}
inline void OpcodeDecoder::Decode_01xxxxxx(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; vsp = vsp - %u\n", Opcode,
((Opcode & 0x3f) << 2) + 4);
}
inline void OpcodeDecoder::Decode_1000iiii_iiiiiiii(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode0 = Opcodes[OI++ ^ 3];
uint8_t Opcode1 = Opcodes[OI++ ^ 3];
uint16_t GPRMask = (Opcode1 << 4) | ((Opcode0 & 0x0f) << 12);
SW.startLine()
<< format("0x%02X 0x%02X ; %s",
Opcode0, Opcode1, GPRMask ? "pop " : "refuse to unwind");
if (GPRMask)
PrintGPR(GPRMask);
OS << '\n';
}
inline void OpcodeDecoder::Decode_10011101(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; reserved (ARM MOVrr)\n", Opcode);
}
inline void OpcodeDecoder::Decode_10011111(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; reserved (WiMMX MOVrr)\n", Opcode);
}
inline void OpcodeDecoder::Decode_1001nnnn(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; vsp = r%u\n", Opcode, (Opcode & 0x0f));
}
inline void OpcodeDecoder::Decode_10100nnn(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; pop ", Opcode);
PrintGPR((((1 << ((Opcode & 0x7) + 1)) - 1) << 4));
OS << '\n';
}
inline void OpcodeDecoder::Decode_10101nnn(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; pop ", Opcode);
PrintGPR((((1 << ((Opcode & 0x7) + 1)) - 1) << 4) | (1 << 14));
OS << '\n';
}
inline void OpcodeDecoder::Decode_10110000(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; finish\n", Opcode);
}
inline void OpcodeDecoder::Decode_10110001_0000iiii(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode0 = Opcodes[OI++ ^ 3];
uint8_t Opcode1 = Opcodes[OI++ ^ 3];
SW.startLine()
<< format("0x%02X 0x%02X ; %s", Opcode0, Opcode1,
((Opcode1 & 0xf0) || Opcode1 == 0x00) ? "spare" : "pop ");
if (((Opcode1 & 0xf0) == 0x00) && Opcode1)
PrintGPR((Opcode1 & 0x0f));
OS << '\n';
}
inline void OpcodeDecoder::Decode_10110010_uleb128(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ", Opcode);
SmallVector<uint8_t, 4> ULEB;
do { ULEB.push_back(Opcodes[OI ^ 3]); } while (Opcodes[OI++ ^ 3] & 0x80);
for (unsigned BI = 0, BE = ULEB.size(); BI != BE; ++BI)
OS << format("0x%02X ", ULEB[BI]);
uint64_t Value = 0;
for (unsigned BI = 0, BE = ULEB.size(); BI != BE; ++BI)
Value = Value | ((ULEB[BI] & 0x7f) << (7 * BI));
OS << format("; vsp = vsp + %" PRIu64 "\n", 0x204 + (Value << 2));
}
inline void OpcodeDecoder::Decode_10110011_sssscccc(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode0 = Opcodes[OI++ ^ 3];
uint8_t Opcode1 = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X 0x%02X ; pop ", Opcode0, Opcode1);
uint8_t Start = ((Opcode1 & 0xf0) >> 4);
uint8_t Count = ((Opcode1 & 0x0f) >> 0);
PrintRegisters((((1 << (Count + 1)) - 1) << Start), "d");
OS << '\n';
}
inline void OpcodeDecoder::Decode_101101nn(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; spare\n", Opcode);
}
inline void OpcodeDecoder::Decode_10111nnn(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; pop ", Opcode);
PrintRegisters((((1 << ((Opcode & 0x07) + 1)) - 1) << 8), "d");
OS << '\n';
}
inline void OpcodeDecoder::Decode_11000110_sssscccc(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode0 = Opcodes[OI++ ^ 3];
uint8_t Opcode1 = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X 0x%02X ; pop ", Opcode0, Opcode1);
uint8_t Start = ((Opcode1 & 0xf0) >> 4);
uint8_t Count = ((Opcode1 & 0x0f) >> 0);
PrintRegisters((((1 << (Count + 1)) - 1) << Start), "wR");
OS << '\n';
}
inline void OpcodeDecoder::Decode_11000111_0000iiii(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode0 = Opcodes[OI++ ^ 3];
uint8_t Opcode1 = Opcodes[OI++ ^ 3];
SW.startLine()
<< format("0x%02X 0x%02X ; %s", Opcode0, Opcode1,
((Opcode1 & 0xf0) || Opcode1 == 0x00) ? "spare" : "pop ");
if ((Opcode1 & 0xf0) == 0x00 && Opcode1)
PrintRegisters(Opcode1 & 0x0f, "wCGR");
OS << '\n';
}
inline void OpcodeDecoder::Decode_11001000_sssscccc(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode0 = Opcodes[OI++ ^ 3];
uint8_t Opcode1 = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X 0x%02X ; pop ", Opcode0, Opcode1);
uint8_t Start = 16 + ((Opcode1 & 0xf0) >> 4);
uint8_t Count = ((Opcode1 & 0x0f) >> 0);
PrintRegisters((((1 << (Count + 1)) - 1) << Start), "d");
OS << '\n';
}
inline void OpcodeDecoder::Decode_11001001_sssscccc(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode0 = Opcodes[OI++ ^ 3];
uint8_t Opcode1 = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X 0x%02X ; pop ", Opcode0, Opcode1);
uint8_t Start = ((Opcode1 & 0xf0) >> 4);
uint8_t Count = ((Opcode1 & 0x0f) >> 0);
PrintRegisters((((1 << (Count + 1)) - 1) << Start), "d");
OS << '\n';
}
inline void OpcodeDecoder::Decode_11001yyy(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; spare\n", Opcode);
}
inline void OpcodeDecoder::Decode_11000nnn(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; pop ", Opcode);
PrintRegisters((((1 << ((Opcode & 0x07) + 1)) - 1) << 10), "wR");
OS << '\n';
}
inline void OpcodeDecoder::Decode_11010nnn(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; pop ", Opcode);
PrintRegisters((((1 << ((Opcode & 0x07) + 1)) - 1) << 8), "d");
OS << '\n';
}
inline void OpcodeDecoder::Decode_11xxxyyy(const uint8_t *Opcodes,
unsigned &OI) {
uint8_t Opcode = Opcodes[OI++ ^ 3];
SW.startLine() << format("0x%02X ; spare\n", Opcode);
}
inline void OpcodeDecoder::PrintGPR(uint16_t GPRMask) {
static const char *GPRRegisterNames[16] = {
"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10",
"fp", "ip", "sp", "lr", "pc"
};
OS << '{';
bool Comma = false;
for (unsigned RI = 0, RE = 17; RI < RE; ++RI) {
if (GPRMask & (1 << RI)) {
if (Comma)
OS << ", ";
OS << GPRRegisterNames[RI];
Comma = true;
}
}
OS << '}';
}
inline void OpcodeDecoder::PrintRegisters(uint32_t VFPMask, StringRef Prefix) {
OS << '{';
bool Comma = false;
for (unsigned RI = 0, RE = 32; RI < RE; ++RI) {
if (VFPMask & (1 << RI)) {
if (Comma)
OS << ", ";
OS << Prefix << RI;
Comma = true;
}
}
OS << '}';
}
inline void OpcodeDecoder::Decode(const uint8_t *Opcodes, off_t Offset,
size_t Length) {
for (unsigned OCI = Offset; OCI < Length + Offset; ) {
bool Decoded = false;
for (const auto &RE : ring()) {
if ((Opcodes[OCI ^ 3] & RE.Mask) == RE.Value) {
(this->*RE.Routine)(Opcodes, OCI);
Decoded = true;
break;
}
}
if (!Decoded)
SW.startLine() << format("0x%02X ; reserved\n", Opcodes[OCI++ ^ 3]);
}
}
template <typename ET>
class PrinterContext {
typedef typename ET::Sym Elf_Sym;
typedef typename ET::Shdr Elf_Shdr;
typedef typename ET::Rel Elf_Rel;
typedef typename ET::Word Elf_Word;
ScopedPrinter &SW;
const object::ELFFile<ET> &ELF;
StringRef FileName;
const Elf_Shdr *Symtab;
ArrayRef<Elf_Word> ShndxTable;
static const size_t IndexTableEntrySize;
static uint64_t PREL31(uint32_t Address, uint32_t Place) {
uint64_t Location = Address & 0x7fffffff;
if (Location & 0x40000000)
Location |= (uint64_t) ~0x7fffffff;
return Location + Place;
}
ErrorOr<StringRef> FunctionAtAddress(uint64_t Address,
Optional<unsigned> SectionIndex) const;
const Elf_Shdr *FindExceptionTable(unsigned IndexTableIndex,
off_t IndexTableOffset) const;
void PrintIndexTable(unsigned SectionIndex, const Elf_Shdr *IT) const;
void PrintExceptionTable(const Elf_Shdr &EHT,
uint64_t TableEntryOffset) const;
void PrintOpcodes(const uint8_t *Entry, size_t Length, off_t Offset) const;
public:
PrinterContext(ScopedPrinter &SW, const object::ELFFile<ET> &ELF,
StringRef FileName, const Elf_Shdr *Symtab)
: SW(SW), ELF(ELF), FileName(FileName), Symtab(Symtab) {}
void PrintUnwindInformation() const;
};
template <typename ET>
const size_t PrinterContext<ET>::IndexTableEntrySize = 8;
template <typename ET>
ErrorOr<StringRef>
PrinterContext<ET>::FunctionAtAddress(uint64_t Address,
Optional<unsigned> SectionIndex) const {
if (!Symtab)
return inconvertibleErrorCode();
auto StrTableOrErr = ELF.getStringTableForSymtab(*Symtab);
if (!StrTableOrErr)
reportError(StrTableOrErr.takeError(), FileName);
StringRef StrTable = *StrTableOrErr;
for (const Elf_Sym &Sym : unwrapOrError(FileName, ELF.symbols(Symtab))) {
if (SectionIndex && *SectionIndex != Sym.st_shndx)
continue;
if (Sym.st_value == Address && Sym.getType() == ELF::STT_FUNC) {
auto NameOrErr = Sym.getName(StrTable);
if (!NameOrErr) {
// TODO: Actually report errors helpfully.
consumeError(NameOrErr.takeError());
return inconvertibleErrorCode();
}
return *NameOrErr;
}
}
return inconvertibleErrorCode();
}
template <typename ET>
const typename ET::Shdr *
PrinterContext<ET>::FindExceptionTable(unsigned IndexSectionIndex,
off_t IndexTableOffset) const {
/// Iterate through the sections, searching for the relocation section
/// associated with the unwind index table section specified by
/// IndexSectionIndex. Iterate the associated section searching for the
/// relocation associated with the index table entry specified by
/// IndexTableOffset. The symbol is the section symbol for the exception
/// handling table. Use this symbol to recover the actual exception handling
/// table.
for (const Elf_Shdr &Sec : unwrapOrError(FileName, ELF.sections())) {
if (Sec.sh_type != ELF::SHT_REL || Sec.sh_info != IndexSectionIndex)
continue;
auto SymTabOrErr = ELF.getSection(Sec.sh_link);
if (!SymTabOrErr)
reportError(SymTabOrErr.takeError(), FileName);
const Elf_Shdr *SymTab = *SymTabOrErr;
for (const Elf_Rel &R : unwrapOrError(FileName, ELF.rels(Sec))) {
if (R.r_offset != static_cast<unsigned>(IndexTableOffset))
continue;
typename ET::Rela RelA;
RelA.r_offset = R.r_offset;
RelA.r_info = R.r_info;
RelA.r_addend = 0;
const Elf_Sym *Symbol =
unwrapOrError(FileName, ELF.getRelocationSymbol(RelA, SymTab));
auto Ret = ELF.getSection(*Symbol, SymTab, ShndxTable);
if (!Ret)
report_fatal_error(errorToErrorCode(Ret.takeError()).message());
return *Ret;
}
}
return nullptr;
}
template <typename ET>
static const typename ET::Shdr *
findSectionContainingAddress(const object::ELFFile<ET> &Obj, StringRef FileName,
uint64_t Address) {
for (const typename ET::Shdr &Sec : unwrapOrError(FileName, Obj.sections()))
if (Address >= Sec.sh_addr && Address < Sec.sh_addr + Sec.sh_size)
return &Sec;
return nullptr;
}
template <typename ET>
void PrinterContext<ET>::PrintExceptionTable(const Elf_Shdr &EHT,
uint64_t TableEntryOffset) const {
// TODO: handle failure.
Expected<ArrayRef<uint8_t>> Contents = ELF.getSectionContents(EHT);
if (!Contents)
return;
/// ARM EHABI Section 6.2 - The generic model
///
/// An exception-handling table entry for the generic model is laid out as:
///
/// 3 3
/// 1 0 0
/// +-+------------------------------+
/// |0| personality routine offset |
/// +-+------------------------------+
/// | personality routine data ... |
///
///
/// ARM EHABI Section 6.3 - The ARM-defined compact model
///
/// An exception-handling table entry for the compact model looks like:
///
/// 3 3 2 2 2 2
/// 1 0 8 7 4 3 0
/// +-+---+----+-----------------------+
/// |1| 0 | Ix | data for pers routine |
/// +-+---+----+-----------------------+
/// | more personality routine data |
const support::ulittle32_t Word =
*reinterpret_cast<const support::ulittle32_t *>(Contents->data() + TableEntryOffset);
if (Word & 0x80000000) {
SW.printString("Model", StringRef("Compact"));
unsigned PersonalityIndex = (Word & 0x0f000000) >> 24;
SW.printNumber("PersonalityIndex", PersonalityIndex);
switch (PersonalityIndex) {
case AEABI_UNWIND_CPP_PR0:
PrintOpcodes(Contents->data() + TableEntryOffset, 3, 1);
break;
case AEABI_UNWIND_CPP_PR1:
case AEABI_UNWIND_CPP_PR2:
unsigned AdditionalWords = (Word & 0x00ff0000) >> 16;
PrintOpcodes(Contents->data() + TableEntryOffset, 2 + 4 * AdditionalWords,
2);
break;
}
} else {
SW.printString("Model", StringRef("Generic"));
const bool IsRelocatable = ELF.getHeader().e_type == ELF::ET_REL;
uint64_t Address = IsRelocatable
? PREL31(Word, EHT.sh_addr)
: PREL31(Word, EHT.sh_addr + TableEntryOffset);
SW.printHex("PersonalityRoutineAddress", Address);
Optional<unsigned> SecIndex =
IsRelocatable ? Optional<unsigned>(EHT.sh_link) : None;
if (ErrorOr<StringRef> Name = FunctionAtAddress(Address, SecIndex))
SW.printString("PersonalityRoutineName", *Name);
}
}
template <typename ET>
void PrinterContext<ET>::PrintOpcodes(const uint8_t *Entry,
size_t Length, off_t Offset) const {
ListScope OCC(SW, "Opcodes");
OpcodeDecoder(OCC.W).Decode(Entry, Offset, Length);
}
template <typename ET>
void PrinterContext<ET>::PrintIndexTable(unsigned SectionIndex,
const Elf_Shdr *IT) const {
// TODO: handle failure.
Expected<ArrayRef<uint8_t>> Contents = ELF.getSectionContents(*IT);
if (!Contents)
return;
/// ARM EHABI Section 5 - Index Table Entries
/// * The first word contains a PREL31 offset to the start of a function with
/// bit 31 clear
/// * The second word contains one of:
/// - The PREL31 offset of the start of the table entry for the function,
/// with bit 31 clear
/// - The exception-handling table entry itself with bit 31 set
/// - The special bit pattern EXIDX_CANTUNWIND, indicating that associated
/// frames cannot be unwound
const support::ulittle32_t *Data =
reinterpret_cast<const support::ulittle32_t *>(Contents->data());
const unsigned Entries = IT->sh_size / IndexTableEntrySize;
const bool IsRelocatable = ELF.getHeader().e_type == ELF::ET_REL;
ListScope E(SW, "Entries");
for (unsigned Entry = 0; Entry < Entries; ++Entry) {
DictScope E(SW, "Entry");
const support::ulittle32_t Word0 =
Data[Entry * (IndexTableEntrySize / sizeof(*Data)) + 0];
const support::ulittle32_t Word1 =
Data[Entry * (IndexTableEntrySize / sizeof(*Data)) + 1];
if (Word0 & 0x80000000) {
errs() << "corrupt unwind data in section " << SectionIndex << "\n";
continue;
}
// FIXME: For a relocatable object ideally we might want to:
// 1) Find a relocation for the offset of Word0.
// 2) Verify this relocation is of an expected type (R_ARM_PREL31) and
// verify the symbol index.
// 3) Resolve the relocation using it's symbol value, addend etc.
// Currently the code assumes that Word0 contains an addend of a
// R_ARM_PREL31 REL relocation that references a section symbol. RELA
// relocations are not supported and it works because addresses of sections
// are nulls in relocatable objects.
//
// For a non-relocatable object, Word0 contains a place-relative signed
// offset to the referenced entity.
const uint64_t Address =
IsRelocatable
? PREL31(Word0, IT->sh_addr)
: PREL31(Word0, IT->sh_addr + Entry * IndexTableEntrySize);
SW.printHex("FunctionAddress", Address);
// In a relocatable output we might have many .ARM.exidx sections linked to
// their code sections via the sh_link field. For a non-relocatable ELF file
// the sh_link field is not reliable, because we have one .ARM.exidx section
// normally, but might have many code sections.
Optional<unsigned> SecIndex =
IsRelocatable ? Optional<unsigned>(IT->sh_link) : None;
if (ErrorOr<StringRef> Name = FunctionAtAddress(Address, SecIndex))
SW.printString("FunctionName", *Name);
if (Word1 == EXIDX_CANTUNWIND) {
SW.printString("Model", StringRef("CantUnwind"));
continue;
}
if (Word1 & 0x80000000) {
SW.printString("Model", StringRef("Compact (Inline)"));
unsigned PersonalityIndex = (Word1 & 0x0f000000) >> 24;
SW.printNumber("PersonalityIndex", PersonalityIndex);
PrintOpcodes(Contents->data() + Entry * IndexTableEntrySize + 4, 3, 1);
} else {
const Elf_Shdr *EHT;
uint64_t TableEntryAddress;
if (IsRelocatable) {
TableEntryAddress = PREL31(Word1, IT->sh_addr);
EHT = FindExceptionTable(SectionIndex, Entry * IndexTableEntrySize + 4);
} else {
TableEntryAddress =
PREL31(Word1, IT->sh_addr + Entry * IndexTableEntrySize + 4);
EHT = findSectionContainingAddress(ELF, FileName, TableEntryAddress);
}
if (EHT)
// TODO: handle failure.
if (Expected<StringRef> Name = ELF.getSectionName(*EHT))
SW.printString("ExceptionHandlingTable", *Name);
SW.printHex(IsRelocatable ? "TableEntryOffset" : "TableEntryAddress",
TableEntryAddress);
if (EHT) {
if (IsRelocatable)
PrintExceptionTable(*EHT, TableEntryAddress);
else
PrintExceptionTable(*EHT, TableEntryAddress - EHT->sh_addr);
}
}
}
}
template <typename ET>
void PrinterContext<ET>::PrintUnwindInformation() const {
DictScope UI(SW, "UnwindInformation");
int SectionIndex = 0;
for (const Elf_Shdr &Sec : unwrapOrError(FileName, ELF.sections())) {
if (Sec.sh_type == ELF::SHT_ARM_EXIDX) {
DictScope UIT(SW, "UnwindIndexTable");
SW.printNumber("SectionIndex", SectionIndex);
// TODO: handle failure.
if (Expected<StringRef> SectionName = ELF.getSectionName(Sec))
SW.printString("SectionName", *SectionName);
SW.printHex("SectionOffset", Sec.sh_offset);
PrintIndexTable(SectionIndex, &Sec);
}
++SectionIndex;
}
}
}
}
}
#endif
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