136 lines
		
	
	
		
			3.7 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			136 lines
		
	
	
		
			3.7 KiB
		
	
	
	
		
			C++
		
	
	
	
//===- DWARFDataExtractor.cpp ---------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
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#include "llvm/DebugInfo/DWARF/DWARFContext.h"
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using namespace llvm;
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std::pair<uint64_t, dwarf::DwarfFormat>
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DWARFDataExtractor::getInitialLength(uint64_t *Off, Error *Err) const {
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  ErrorAsOutParameter ErrAsOut(Err);
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  if (Err && *Err)
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    return {0, dwarf::DWARF32};
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  Cursor C(*Off);
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  uint64_t Length = getRelocatedValue(C, 4);
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  dwarf::DwarfFormat Format = dwarf::DWARF32;
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  if (Length == dwarf::DW_LENGTH_DWARF64) {
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    Length = getRelocatedValue(C, 8);
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    Format = dwarf::DWARF64;
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  } else if (Length >= dwarf::DW_LENGTH_lo_reserved) {
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    cantFail(C.takeError());
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    if (Err)
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      *Err = createStringError(
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          errc::invalid_argument,
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          "unsupported reserved unit length of value 0x%8.8" PRIx64, Length);
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    return {0, dwarf::DWARF32};
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  }
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  if (C) {
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    *Off = C.tell();
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    return {Length, Format};
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  }
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  if (Err)
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    *Err = C.takeError();
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  else
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    consumeError(C.takeError());
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  return {0, dwarf::DWARF32};
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}
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uint64_t DWARFDataExtractor::getRelocatedValue(uint32_t Size, uint64_t *Off,
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                                               uint64_t *SecNdx,
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                                               Error *Err) const {
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  if (SecNdx)
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    *SecNdx = object::SectionedAddress::UndefSection;
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  if (!Section)
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    return getUnsigned(Off, Size, Err);
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  ErrorAsOutParameter ErrAsOut(Err);
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  Optional<RelocAddrEntry> E = Obj->find(*Section, *Off);
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  uint64_t LocData = getUnsigned(Off, Size, Err);
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  if (!E || (Err && *Err))
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    return LocData;
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  if (SecNdx)
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    *SecNdx = E->SectionIndex;
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  uint64_t R =
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      object::resolveRelocation(E->Resolver, E->Reloc, E->SymbolValue, LocData);
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  if (E->Reloc2)
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    R = object::resolveRelocation(E->Resolver, *E->Reloc2, E->SymbolValue2, R);
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  return R;
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}
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Optional<uint64_t>
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DWARFDataExtractor::getEncodedPointer(uint64_t *Offset, uint8_t Encoding,
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                                      uint64_t PCRelOffset) const {
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  if (Encoding == dwarf::DW_EH_PE_omit)
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    return None;
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  uint64_t Result = 0;
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  uint64_t OldOffset = *Offset;
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  // First get value
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  switch (Encoding & 0x0F) {
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  case dwarf::DW_EH_PE_absptr:
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    switch (getAddressSize()) {
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    case 2:
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    case 4:
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    case 8:
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      Result = getUnsigned(Offset, getAddressSize());
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      break;
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    default:
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      return None;
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    }
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    break;
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  case dwarf::DW_EH_PE_uleb128:
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    Result = getULEB128(Offset);
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    break;
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  case dwarf::DW_EH_PE_sleb128:
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    Result = getSLEB128(Offset);
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    break;
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  case dwarf::DW_EH_PE_udata2:
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    Result = getUnsigned(Offset, 2);
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    break;
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  case dwarf::DW_EH_PE_udata4:
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    Result = getUnsigned(Offset, 4);
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    break;
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  case dwarf::DW_EH_PE_udata8:
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    Result = getUnsigned(Offset, 8);
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    break;
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  case dwarf::DW_EH_PE_sdata2:
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    Result = getSigned(Offset, 2);
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    break;
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  case dwarf::DW_EH_PE_sdata4:
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    Result = SignExtend64<32>(getRelocatedValue(4, Offset));
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    break;
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  case dwarf::DW_EH_PE_sdata8:
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    Result = getRelocatedValue(8, Offset);
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    break;
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  default:
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    return None;
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  }
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  // Then add relative offset, if required
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  switch (Encoding & 0x70) {
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  case dwarf::DW_EH_PE_absptr:
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    // do nothing
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    break;
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  case dwarf::DW_EH_PE_pcrel:
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    Result += PCRelOffset;
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    break;
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  case dwarf::DW_EH_PE_datarel:
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  case dwarf::DW_EH_PE_textrel:
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  case dwarf::DW_EH_PE_funcrel:
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  case dwarf::DW_EH_PE_aligned:
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  default:
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    *Offset = OldOffset;
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    return None;
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  }
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  return Result;
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}
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