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//===-- lib/CodeGen/ELF.h - ELF constants and data structures ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This header contains common, non-processor-specific data structures and
// constants for the ELF file format.
//
// The details of the ELF32 bits in this file are largely based on the Tool
// Interface Standard (TIS) Executable and Linking Format (ELF) Specification
// Version 1.2, May 1995. The ELF64 is based on HP/Intel definition of the
// ELF-64 object file format document, Version 1.5 Draft 2 May 27, 1998
//
//===----------------------------------------------------------------------===//
#ifndef CODEGEN_ELF_H
#define CODEGEN_ELF_H
#include "llvm/CodeGen/BinaryObject.h"
#include "llvm/CodeGen/MachineRelocation.h"
#include "llvm/Support/ELF.h"
#include "llvm/System/DataTypes.h"
namespace llvm {
class GlobalValue;
/// ELFSym - This struct contains information about each symbol that is
/// added to logical symbol table for the module. This is eventually
/// turned into a real symbol table in the file.
struct ELFSym {
// ELF symbols are related to llvm ones by being one of the two llvm
// types, for the other ones (section, file, func) a null pointer is
// assumed by default.
union {
const GlobalValue *GV; // If this is a pointer to a GV
const char *Ext; // If this is a pointer to a named symbol
} Source;
// Describes from which source type this ELF symbol comes from,
// they can be GlobalValue, ExternalSymbol or neither.
enum {
isGV, // The Source.GV field is valid.
isExtSym, // The Source.ExtSym field is valid.
isOther // Not a GlobalValue or External Symbol
};
unsigned SourceType;
bool isGlobalValue() const { return SourceType == isGV; }
bool isExternalSym() const { return SourceType == isExtSym; }
// getGlobalValue - If this is a global value which originated the
// elf symbol, return a reference to it.
const GlobalValue *getGlobalValue() const {
assert(SourceType == isGV && "This is not a global value");
return Source.GV;
}
// getExternalSym - If this is an external symbol which originated the
// elf symbol, return a reference to it.
const char *getExternalSymbol() const {
assert(SourceType == isExtSym && "This is not an external symbol");
return Source.Ext;
}
// getGV - From a global value return a elf symbol to represent it
static ELFSym *getGV(const GlobalValue *GV, unsigned Bind,
unsigned Type, unsigned Visibility) {
ELFSym *Sym = new ELFSym();
Sym->Source.GV = GV;
Sym->setBind(Bind);
Sym->setType(Type);
Sym->setVisibility(Visibility);
Sym->SourceType = isGV;
return Sym;
}
// getExtSym - Create and return an elf symbol to represent an
// external symbol
static ELFSym *getExtSym(const char *Ext) {
ELFSym *Sym = new ELFSym();
Sym->Source.Ext = Ext;
Sym->setBind(ELF::STB_GLOBAL);
Sym->setType(ELF::STT_NOTYPE);
Sym->setVisibility(ELF::STV_DEFAULT);
Sym->SourceType = isExtSym;
return Sym;
}
// getSectionSym - Returns a elf symbol to represent an elf section
static ELFSym *getSectionSym() {
ELFSym *Sym = new ELFSym();
Sym->setBind(ELF::STB_LOCAL);
Sym->setType(ELF::STT_SECTION);
Sym->setVisibility(ELF::STV_DEFAULT);
Sym->SourceType = isOther;
return Sym;
}
// getFileSym - Returns a elf symbol to represent the module identifier
static ELFSym *getFileSym() {
ELFSym *Sym = new ELFSym();
Sym->setBind(ELF::STB_LOCAL);
Sym->setType(ELF::STT_FILE);
Sym->setVisibility(ELF::STV_DEFAULT);
Sym->SectionIdx = 0xfff1; // ELFSection::SHN_ABS;
Sym->SourceType = isOther;
return Sym;
}
// getUndefGV - Returns a STT_NOTYPE symbol
static ELFSym *getUndefGV(const GlobalValue *GV, unsigned Bind) {
ELFSym *Sym = new ELFSym();
Sym->Source.GV = GV;
Sym->setBind(Bind);
Sym->setType(ELF::STT_NOTYPE);
Sym->setVisibility(ELF::STV_DEFAULT);
Sym->SectionIdx = 0; //ELFSection::SHN_UNDEF;
Sym->SourceType = isGV;
return Sym;
}
// ELF specific fields
unsigned NameIdx; // Index in .strtab of name, once emitted.
uint64_t Value;
unsigned Size;
uint8_t Info;
uint8_t Other;
unsigned short SectionIdx;
// Symbol index into the Symbol table
unsigned SymTabIdx;
ELFSym() : SourceType(isOther), NameIdx(0), Value(0),
Size(0), Info(0), Other(ELF::STV_DEFAULT), SectionIdx(0),
SymTabIdx(0) {}
unsigned getBind() const { return (Info >> 4) & 0xf; }
unsigned getType() const { return Info & 0xf; }
bool isLocalBind() const { return getBind() == ELF::STB_LOCAL; }
bool isFileType() const { return getType() == ELF::STT_FILE; }
void setBind(unsigned X) {
assert(X == (X & 0xF) && "Bind value out of range!");
Info = (Info & 0x0F) | (X << 4);
}
void setType(unsigned X) {
assert(X == (X & 0xF) && "Type value out of range!");
Info = (Info & 0xF0) | X;
}
void setVisibility(unsigned V) {
assert(V == (V & 0x3) && "Visibility value out of range!");
Other = V;
}
};
/// ELFSection - This struct contains information about each section that is
/// emitted to the file. This is eventually turned into the section header
/// table at the end of the file.
class ELFSection : public BinaryObject {
public:
// ELF specific fields
unsigned NameIdx; // sh_name - .shstrtab idx of name, once emitted.
unsigned Type; // sh_type - Section contents & semantics
unsigned Flags; // sh_flags - Section flags.
uint64_t Addr; // sh_addr - The mem addr this section is in.
unsigned Offset; // sh_offset - Offset from the file start
unsigned Size; // sh_size - The section size.
unsigned Link; // sh_link - Section header table index link.
unsigned Info; // sh_info - Auxillary information.
unsigned Align; // sh_addralign - Alignment of section.
unsigned EntSize; // sh_entsize - Size of entries in the section e
/// SectionIdx - The number of the section in the Section Table.
unsigned short SectionIdx;
/// Sym - The symbol to represent this section if it has one.
ELFSym *Sym;
/// getSymIndex - Returns the symbol table index of the symbol
/// representing this section.
unsigned getSymbolTableIndex() const {
assert(Sym && "section not present in the symbol table");
return Sym->SymTabIdx;
}
ELFSection(const std::string &name, bool isLittleEndian, bool is64Bit)
: BinaryObject(name, isLittleEndian, is64Bit), Type(0), Flags(0), Addr(0),
Offset(0), Size(0), Link(0), Info(0), Align(0), EntSize(0), Sym(0) {}
};
/// ELFRelocation - This class contains all the information necessary to
/// to generate any 32-bit or 64-bit ELF relocation entry.
class ELFRelocation {
uint64_t r_offset; // offset in the section of the object this applies to
uint32_t r_symidx; // symbol table index of the symbol to use
uint32_t r_type; // machine specific relocation type
int64_t r_add; // explicit relocation addend
bool r_rela; // if true then the addend is part of the entry
// otherwise the addend is at the location specified
// by r_offset
public:
uint64_t getInfo(bool is64Bit) const {
if (is64Bit)
return ((uint64_t)r_symidx << 32) + ((uint64_t)r_type & 0xFFFFFFFFL);
else
return (r_symidx << 8) + (r_type & 0xFFL);
}
uint64_t getOffset() const { return r_offset; }
int64_t getAddend() const { return r_add; }
ELFRelocation(uint64_t off, uint32_t sym, uint32_t type,
bool rela = true, int64_t addend = 0) :
r_offset(off), r_symidx(sym), r_type(type),
r_add(addend), r_rela(rela) {}
};
} // end namespace llvm
#endif
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