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//===-- RelocVisitor.h - Visitor for object file relocations -*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides a wrapper around all the different types of relocations
// in different file formats, such that a client can handle them in a unified
// manner by only implementing a minimal number of functions.
//
//===----------------------------------------------------------------------===//
#ifndef _LLVM_OBJECT_RELOCVISITOR
#define _LLVM_OBJECT_RELOCVISITOR
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Object/ELF.h"
#include "llvm/ADT/StringRef.h"
namespace llvm {
namespace object {
struct RelocToApply {
// The computed value after applying the relevant relocations.
int64_t Value;
// The width of the value; how many bytes to touch when applying the
// relocation.
char Width;
RelocToApply(const RelocToApply &In) : Value(In.Value), Width(In.Width) {}
RelocToApply(int64_t Value, char Width) : Value(Value), Width(Width) {}
RelocToApply() : Value(0), Width(0) {}
};
/// @brief Base class for object file relocation visitors.
class RelocVisitor {
public:
explicit RelocVisitor(llvm::StringRef FileFormat)
: FileFormat(FileFormat), HasError(false) {}
// TODO: Should handle multiple applied relocations via either passing in the
// previously computed value or just count paired relocations as a single
// visit.
RelocToApply visit(uint32_t RelocType, RelocationRef R, uint64_t SecAddr = 0,
uint64_t Value = 0) {
if (FileFormat == "ELF64-x86-64") {
switch (RelocType) {
case llvm::ELF::R_X86_64_NONE:
return visitELF_X86_64_NONE(R);
case llvm::ELF::R_X86_64_64:
return visitELF_X86_64_64(R, Value);
case llvm::ELF::R_X86_64_PC32:
return visitELF_X86_64_PC32(R, Value, SecAddr);
case llvm::ELF::R_X86_64_32:
return visitELF_X86_64_32(R, Value);
case llvm::ELF::R_X86_64_32S:
return visitELF_X86_64_32S(R, Value);
default:
HasError = true;
return RelocToApply();
}
}
return RelocToApply();
}
bool error() { return HasError; }
private:
llvm::StringRef FileFormat;
bool HasError;
/// Operations
// Width is the width in bytes of the extend.
RelocToApply zeroExtend(RelocToApply r, char Width) {
if (Width == r.Width)
return r;
r.Value &= (1 << ((Width * 8))) - 1;
return r;
}
RelocToApply signExtend(RelocToApply r, char Width) {
if (Width == r.Width)
return r;
bool SignBit = r.Value & (1 << ((Width * 8) - 1));
if (SignBit) {
r.Value |= ~((1 << (Width * 8)) - 1);
} else {
r.Value &= (1 << (Width * 8)) - 1;
}
return r;
}
/// X86-64 ELF
RelocToApply visitELF_X86_64_NONE(RelocationRef R) {
return RelocToApply(0, 0);
}
RelocToApply visitELF_X86_64_64(RelocationRef R, uint64_t Value) {
int64_t Addend;
R.getAdditionalInfo(Addend);
return RelocToApply(Value + Addend, 8);
}
RelocToApply visitELF_X86_64_PC32(RelocationRef R, uint64_t Value,
uint64_t SecAddr) {
int64_t Addend;
R.getAdditionalInfo(Addend);
uint64_t Address;
R.getAddress(Address);
return RelocToApply(Value + Addend - Address, 4);
}
RelocToApply visitELF_X86_64_32(RelocationRef R, uint64_t Value) {
int64_t Addend;
R.getAdditionalInfo(Addend);
uint32_t Res = (Value + Addend) & 0xFFFFFFFF;
return RelocToApply(Res, 4);
}
RelocToApply visitELF_X86_64_32S(RelocationRef R, uint64_t Value) {
int64_t Addend;
R.getAdditionalInfo(Addend);
int32_t Res = (Value + Addend) & 0xFFFFFFFF;
return RelocToApply(Res, 4);
}
};
}
}
#endif
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