//===-- 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/System/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 }; /// 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(STB_GLOBAL); Sym->setType(STT_NOTYPE); Sym->setVisibility(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(STB_LOCAL); Sym->setType(STT_SECTION); Sym->setVisibility(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(STB_LOCAL); Sym->setType(STT_FILE); Sym->setVisibility(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(STT_NOTYPE); Sym->setVisibility(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; enum { STB_LOCAL = 0, // Local sym, not visible outside obj file containing def STB_GLOBAL = 1, // Global sym, visible to all object files being combined STB_WEAK = 2 // Weak symbol, like global but lower-precedence }; enum { STT_NOTYPE = 0, // Symbol's type is not specified STT_OBJECT = 1, // Symbol is a data object (variable, array, etc.) STT_FUNC = 2, // Symbol is executable code (function, etc.) STT_SECTION = 3, // Symbol refers to a section STT_FILE = 4 // Local, absolute symbol that refers to a file }; 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() : SourceType(isOther), NameIdx(0), Value(0), Size(0), Info(0), Other(STV_DEFAULT), SectionIdx(0), SymTabIdx(0) {} unsigned getBind() const { return (Info >> 4) & 0xf; } unsigned getType() const { return Info & 0xf; } bool isLocalBind() const { return getBind() == STB_LOCAL; } bool isFileType() const { return getType() == 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 // 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; /// 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