242 lines
8.5 KiB
C++
242 lines
8.5 KiB
C++
//===-- lib/CodeGen/ELF.h - ELF constants and data structures ---*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This header contains common, non-processor-specific data structures and
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// constants for the ELF file format.
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//
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// The details of the ELF32 bits in this file are largely based on the Tool
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// Interface Standard (TIS) Executable and Linking Format (ELF) Specification
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// Version 1.2, May 1995. The ELF64 is based on HP/Intel definition of the
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// ELF-64 object file format document, Version 1.5 Draft 2 May 27, 1998
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//
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//===----------------------------------------------------------------------===//
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#ifndef CODEGEN_ELF_H
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#define CODEGEN_ELF_H
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#include "llvm/GlobalVariable.h"
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#include "llvm/CodeGen/BinaryObject.h"
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#include "llvm/CodeGen/MachineRelocation.h"
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#include "llvm/Support/DataTypes.h"
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#include <cstring>
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namespace llvm {
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class BinaryObject;
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// Identification Indexes
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enum {
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EI_MAG0 = 0,
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EI_MAG1 = 1,
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EI_MAG2 = 2,
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EI_MAG3 = 3
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};
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// File types
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enum {
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ET_NONE = 0, // No file type
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ET_REL = 1, // Relocatable file
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ET_EXEC = 2, // Executable file
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ET_DYN = 3, // Shared object file
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ET_CORE = 4, // Core file
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ET_LOPROC = 0xff00, // Beginning of processor-specific codes
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ET_HIPROC = 0xffff // Processor-specific
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};
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// Versioning
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enum {
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EV_NONE = 0,
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EV_CURRENT = 1
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};
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/// ELFSection - This struct contains information about each section that is
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/// emitted to the file. This is eventually turned into the section header
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/// table at the end of the file.
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class ELFSection : public BinaryObject {
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public:
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// ELF specific fields
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unsigned NameIdx; // sh_name - .shstrtab idx of name, once emitted.
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unsigned Type; // sh_type - Section contents & semantics
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unsigned Flags; // sh_flags - Section flags.
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uint64_t Addr; // sh_addr - The mem addr this section is in.
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unsigned Offset; // sh_offset - Offset from the file start
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unsigned Size; // sh_size - The section size.
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unsigned Link; // sh_link - Section header table index link.
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unsigned Info; // sh_info - Auxillary information.
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unsigned Align; // sh_addralign - Alignment of section.
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unsigned EntSize; // sh_entsize - Size of entries in the section e
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// Section Header Flags
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enum {
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SHF_WRITE = 1 << 0, // Writable
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SHF_ALLOC = 1 << 1, // Mapped into the process addr space
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SHF_EXECINSTR = 1 << 2, // Executable
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SHF_MERGE = 1 << 4, // Might be merged if equal
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SHF_STRINGS = 1 << 5, // Contains null-terminated strings
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SHF_INFO_LINK = 1 << 6, // 'sh_info' contains SHT index
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SHF_LINK_ORDER = 1 << 7, // Preserve order after combining
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SHF_OS_NONCONFORMING = 1 << 8, // nonstandard OS support required
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SHF_GROUP = 1 << 9, // Section is a member of a group
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SHF_TLS = 1 << 10 // Section holds thread-local data
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};
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// Section Types
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enum {
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SHT_NULL = 0, // No associated section (inactive entry).
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SHT_PROGBITS = 1, // Program-defined contents.
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SHT_SYMTAB = 2, // Symbol table.
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SHT_STRTAB = 3, // String table.
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SHT_RELA = 4, // Relocation entries; explicit addends.
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SHT_HASH = 5, // Symbol hash table.
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SHT_DYNAMIC = 6, // Information for dynamic linking.
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SHT_NOTE = 7, // Information about the file.
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SHT_NOBITS = 8, // Data occupies no space in the file.
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SHT_REL = 9, // Relocation entries; no explicit addends.
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SHT_SHLIB = 10, // Reserved.
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SHT_DYNSYM = 11, // Symbol table.
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SHT_LOPROC = 0x70000000, // Lowest processor arch-specific type.
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SHT_HIPROC = 0x7fffffff, // Highest processor arch-specific type.
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SHT_LOUSER = 0x80000000, // Lowest type reserved for applications.
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SHT_HIUSER = 0xffffffff // Highest type reserved for applications.
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};
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// Special section indices.
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enum {
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SHN_UNDEF = 0, // Undefined, missing, irrelevant
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SHN_LORESERVE = 0xff00, // Lowest reserved index
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SHN_LOPROC = 0xff00, // Lowest processor-specific index
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SHN_HIPROC = 0xff1f, // Highest processor-specific index
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SHN_ABS = 0xfff1, // Symbol has absolute value; no relocation
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SHN_COMMON = 0xfff2, // FORTRAN COMMON or C external global variables
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SHN_HIRESERVE = 0xffff // Highest reserved index
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};
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/// SectionIdx - The number of the section in the Section Table.
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unsigned short SectionIdx;
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ELFSection(const std::string &name, bool isLittleEndian, bool is64Bit)
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: BinaryObject(name, isLittleEndian, is64Bit), Type(0), Flags(0), Addr(0),
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Offset(0), Size(0), Link(0), Info(0), Align(0), EntSize(0) {}
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};
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/// ELFSym - This struct contains information about each symbol that is
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/// added to logical symbol table for the module. This is eventually
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/// turned into a real symbol table in the file.
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struct ELFSym {
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// The global value this corresponds to. Global symbols can be on of the
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// 3 types : if this symbol has a zero initializer, it is common or should
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// be placed in bss section otherwise it's a constant.
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const GlobalValue *GV;
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bool IsCommon;
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bool IsBss;
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bool IsConstant;
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// ELF specific fields
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unsigned NameIdx; // Index in .strtab of name, once emitted.
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uint64_t Value;
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unsigned Size;
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uint8_t Info;
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uint8_t Other;
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unsigned short SectionIdx;
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// Symbol index into the Symbol table
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unsigned SymTabIdx;
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enum {
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STB_LOCAL = 0,
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STB_GLOBAL = 1,
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STB_WEAK = 2
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};
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enum {
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STT_NOTYPE = 0,
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STT_OBJECT = 1,
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STT_FUNC = 2,
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STT_SECTION = 3,
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STT_FILE = 4
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};
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enum {
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STV_DEFAULT = 0, // Visibility is specified by binding type
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STV_INTERNAL = 1, // Defined by processor supplements
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STV_HIDDEN = 2, // Not visible to other components
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STV_PROTECTED = 3 // Visible in other components but not preemptable
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};
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ELFSym(const GlobalValue *gv) : GV(gv), IsCommon(false), IsBss(false),
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IsConstant(false), NameIdx(0), Value(0),
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Size(0), Info(0), Other(STV_DEFAULT),
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SectionIdx(ELFSection::SHN_UNDEF),
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SymTabIdx(0) {
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if (!GV)
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return;
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switch (GV->getVisibility()) {
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default:
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assert(0 && "unknown visibility type");
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case GlobalValue::DefaultVisibility:
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Other = STV_DEFAULT;
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break;
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case GlobalValue::HiddenVisibility:
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Other = STV_HIDDEN;
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break;
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case GlobalValue::ProtectedVisibility:
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Other = STV_PROTECTED;
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break;
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}
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}
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unsigned getBind() {
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return (Info >> 4) & 0xf;
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}
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unsigned getType() {
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return Info & 0xf;
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}
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void setBind(unsigned X) {
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assert(X == (X & 0xF) && "Bind value out of range!");
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Info = (Info & 0x0F) | (X << 4);
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}
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void setType(unsigned X) {
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assert(X == (X & 0xF) && "Type value out of range!");
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Info = (Info & 0xF0) | X;
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}
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};
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/// ELFRelocation - This class contains all the information necessary to
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/// to generate any 32-bit or 64-bit ELF relocation entry.
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class ELFRelocation {
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uint64_t r_offset; // offset in the section of the object this applies to
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uint32_t r_symidx; // symbol table index of the symbol to use
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uint32_t r_type; // machine specific relocation type
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int64_t r_add; // explicit relocation addend
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bool r_rela; // if true then the addend is part of the entry
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// otherwise the addend is at the location specified
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// by r_offset
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public:
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uint64_t getInfo(bool is64Bit) const {
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if (is64Bit)
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return ((uint64_t)r_symidx << 32) + ((uint64_t)r_type & 0xFFFFFFFFL);
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else
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return (r_symidx << 8) + (r_type & 0xFFL);
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}
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uint64_t getOffset() const { return r_offset; }
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int64_t getAddend() const { return r_add; }
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ELFRelocation(uint64_t off, uint32_t sym, uint32_t type,
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bool rela = true, int64_t addend = 0) :
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r_offset(off), r_symidx(sym), r_type(type),
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r_add(addend), r_rela(rela) {}
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};
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} // end namespace llvm
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#endif
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