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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/DataTypes.h"
namespace llvm {
class GlobalValue;
// Identification Indexes
enum {
EI_MAG0 = 0,
EI_MAG1 = 1,
EI_MAG2 = 2,
EI_MAG3 = 3
};
// File types
enum {
ET_NONE = 0, // No file type
ET_REL = 1, // Relocatable file
ET_EXEC = 2, // Executable file
ET_DYN = 3, // Shared object file
ET_CORE = 4, // Core file
ET_LOPROC = 0xff00, // Beginning of processor-specific codes
ET_HIPROC = 0xffff // Processor-specific
};
// Versioning
enum {
EV_NONE = 0,
EV_CURRENT = 1
};
/// 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
// Section Header Flags
enum {
SHF_WRITE = 1 << 0, // Writable
SHF_ALLOC = 1 << 1, // Mapped into the process addr space
SHF_EXECINSTR = 1 << 2, // Executable
SHF_MERGE = 1 << 4, // Might be merged if equal
SHF_STRINGS = 1 << 5, // Contains null-terminated strings
SHF_INFO_LINK = 1 << 6, // 'sh_info' contains SHT index
SHF_LINK_ORDER = 1 << 7, // Preserve order after combining
SHF_OS_NONCONFORMING = 1 << 8, // nonstandard OS support required
SHF_GROUP = 1 << 9, // Section is a member of a group
SHF_TLS = 1 << 10 // Section holds thread-local data
};
// Section Types
enum {
SHT_NULL = 0, // No associated section (inactive entry).
SHT_PROGBITS = 1, // Program-defined contents.
SHT_SYMTAB = 2, // Symbol table.
SHT_STRTAB = 3, // String table.
SHT_RELA = 4, // Relocation entries; explicit addends.
SHT_HASH = 5, // Symbol hash table.
SHT_DYNAMIC = 6, // Information for dynamic linking.
SHT_NOTE = 7, // Information about the file.
SHT_NOBITS = 8, // Data occupies no space in the file.
SHT_REL = 9, // Relocation entries; no explicit addends.
SHT_SHLIB = 10, // Reserved.
SHT_DYNSYM = 11, // Symbol table.
SHT_LOPROC = 0x70000000, // Lowest processor arch-specific type.
SHT_HIPROC = 0x7fffffff, // Highest processor arch-specific type.
SHT_LOUSER = 0x80000000, // Lowest type reserved for applications.
SHT_HIUSER = 0xffffffff // Highest type reserved for applications.
};
// Special section indices.
enum {
SHN_UNDEF = 0, // Undefined, missing, irrelevant
SHN_LORESERVE = 0xff00, // Lowest reserved index
SHN_LOPROC = 0xff00, // Lowest processor-specific index
SHN_HIPROC = 0xff1f, // Highest processor-specific index
SHN_ABS = 0xfff1, // Symbol has absolute value; no relocation
SHN_COMMON = 0xfff2, // FORTRAN COMMON or C external global variables
SHN_HIRESERVE = 0xffff // Highest reserved index
};
/// SectionIdx - The number of the section in the Section Table.
unsigned short SectionIdx;
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) {}
};
/// 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 {
// The global value this corresponds to. Global symbols can be on of the
// 3 types : if this symbol has a zero initializer, it is common or should
// be placed in bss section otherwise it's a constant.
const GlobalValue *GV;
bool IsCommon;
bool IsBss;
bool IsConstant;
// 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;
enum {
STB_LOCAL = 0,
STB_GLOBAL = 1,
STB_WEAK = 2
};
enum {
STT_NOTYPE = 0,
STT_OBJECT = 1,
STT_FUNC = 2,
STT_SECTION = 3,
STT_FILE = 4
};
enum {
STV_DEFAULT = 0, // Visibility is specified by binding type
STV_INTERNAL = 1, // Defined by processor supplements
STV_HIDDEN = 2, // Not visible to other components
STV_PROTECTED = 3 // Visible in other components but not preemptable
};
ELFSym(const GlobalValue *gv) : GV(gv), IsCommon(false), IsBss(false),
IsConstant(false), NameIdx(0), Value(0),
Size(0), Info(0), Other(STV_DEFAULT),
SectionIdx(ELFSection::SHN_UNDEF),
SymTabIdx(0) {}
unsigned getBind() { return (Info >> 4) & 0xf; }
unsigned getType() { return Info & 0xf; }
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) && "Type value out of range!");
Other = V;
}
};
/// 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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