コード例 #1
0
ファイル: objfile.go プロジェクト: Mokolea/go
func LoadObjFile(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
	start := f.Offset()
	r := &objReader{
		rd:     f.Reader,
		pkg:    pkg,
		ctxt:   ctxt,
		pn:     pn,
		dupSym: &Symbol{Name: ".dup"},
	}
	r.loadObjFile()
	if f.Offset() != start+length {
		log.Fatalf("%s: unexpected end at %d, want %d", pn, f.Offset(), start+length)
	}
}
コード例 #2
0
ファイル: objfile.go プロジェクト: achanda/go
func LoadObjFile(ctxt *Link, f *bio.Reader, lib *Library, length int64, pn string) {

	start := f.Offset()
	r := &objReader{
		rd:              f.Reader,
		lib:             lib,
		ctxt:            ctxt,
		pn:              pn,
		dupSym:          &Symbol{Name: ".dup"},
		localSymVersion: ctxt.Syms.IncVersion(),
	}
	r.loadObjFile()
	if f.Offset() != start+length {
		log.Fatalf("%s: unexpected end at %d, want %d", pn, f.Offset(), start+length)
	}
}
コード例 #3
0
ファイル: ldelf.go プロジェクト: achanda/go
func ldelf(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
	if ctxt.Debugvlog != 0 {
		ctxt.Logf("%5.2f ldelf %s\n", obj.Cputime(), pn)
	}

	localSymVersion := ctxt.Syms.IncVersion()
	base := f.Offset()

	var add uint64
	var e binary.ByteOrder
	var elfobj *ElfObj
	var err error
	var flag int
	var hdr *ElfHdrBytes
	var hdrbuf [64]uint8
	var info uint64
	var is64 int
	var j int
	var n int
	var name string
	var p []byte
	var r []Reloc
	var rela int
	var rp *Reloc
	var rsect *ElfSect
	var s *Symbol
	var sect *ElfSect
	var sym ElfSym
	var symbols []*Symbol
	if _, err := io.ReadFull(f, hdrbuf[:]); err != nil {
		goto bad
	}
	hdr = new(ElfHdrBytes)
	binary.Read(bytes.NewReader(hdrbuf[:]), binary.BigEndian, hdr) // only byte arrays; byte order doesn't matter
	if string(hdr.Ident[:4]) != "\x7FELF" {
		goto bad
	}
	switch hdr.Ident[5] {
	case ElfDataLsb:
		e = binary.LittleEndian

	case ElfDataMsb:
		e = binary.BigEndian

	default:
		goto bad
	}

	// read header
	elfobj = new(ElfObj)

	elfobj.e = e
	elfobj.f = f
	elfobj.base = base
	elfobj.length = length
	elfobj.name = pn

	is64 = 0
	if hdr.Ident[4] == ElfClass64 {
		is64 = 1
		hdr := new(ElfHdrBytes64)
		binary.Read(bytes.NewReader(hdrbuf[:]), binary.BigEndian, hdr) // only byte arrays; byte order doesn't matter
		elfobj.type_ = uint32(e.Uint16(hdr.Type[:]))
		elfobj.machine = uint32(e.Uint16(hdr.Machine[:]))
		elfobj.version = e.Uint32(hdr.Version[:])
		elfobj.phoff = e.Uint64(hdr.Phoff[:])
		elfobj.shoff = e.Uint64(hdr.Shoff[:])
		elfobj.flags = e.Uint32(hdr.Flags[:])
		elfobj.ehsize = uint32(e.Uint16(hdr.Ehsize[:]))
		elfobj.phentsize = uint32(e.Uint16(hdr.Phentsize[:]))
		elfobj.phnum = uint32(e.Uint16(hdr.Phnum[:]))
		elfobj.shentsize = uint32(e.Uint16(hdr.Shentsize[:]))
		elfobj.shnum = uint32(e.Uint16(hdr.Shnum[:]))
		elfobj.shstrndx = uint32(e.Uint16(hdr.Shstrndx[:]))
	} else {
		elfobj.type_ = uint32(e.Uint16(hdr.Type[:]))
		elfobj.machine = uint32(e.Uint16(hdr.Machine[:]))
		elfobj.version = e.Uint32(hdr.Version[:])
		elfobj.entry = uint64(e.Uint32(hdr.Entry[:]))
		elfobj.phoff = uint64(e.Uint32(hdr.Phoff[:]))
		elfobj.shoff = uint64(e.Uint32(hdr.Shoff[:]))
		elfobj.flags = e.Uint32(hdr.Flags[:])
		elfobj.ehsize = uint32(e.Uint16(hdr.Ehsize[:]))
		elfobj.phentsize = uint32(e.Uint16(hdr.Phentsize[:]))
		elfobj.phnum = uint32(e.Uint16(hdr.Phnum[:]))
		elfobj.shentsize = uint32(e.Uint16(hdr.Shentsize[:]))
		elfobj.shnum = uint32(e.Uint16(hdr.Shnum[:]))
		elfobj.shstrndx = uint32(e.Uint16(hdr.Shstrndx[:]))
	}

	elfobj.is64 = is64

	if uint32(hdr.Ident[6]) != elfobj.version {
		goto bad
	}

	if e.Uint16(hdr.Type[:]) != ElfTypeRelocatable {
		Errorf(nil, "%s: elf but not elf relocatable object", pn)
		return
	}

	switch SysArch.Family {
	default:
		Errorf(nil, "%s: elf %s unimplemented", pn, SysArch.Name)
		return

	case sys.MIPS64:
		if elfobj.machine != ElfMachMips || hdr.Ident[4] != ElfClass64 {
			Errorf(nil, "%s: elf object but not mips64", pn)
			return
		}

	case sys.ARM:
		if e != binary.LittleEndian || elfobj.machine != ElfMachArm || hdr.Ident[4] != ElfClass32 {
			Errorf(nil, "%s: elf object but not arm", pn)
			return
		}

	case sys.AMD64:
		if e != binary.LittleEndian || elfobj.machine != ElfMachAmd64 || hdr.Ident[4] != ElfClass64 {
			Errorf(nil, "%s: elf object but not amd64", pn)
			return
		}

	case sys.ARM64:
		if e != binary.LittleEndian || elfobj.machine != ElfMachArm64 || hdr.Ident[4] != ElfClass64 {
			Errorf(nil, "%s: elf object but not arm64", pn)
			return
		}

	case sys.I386:
		if e != binary.LittleEndian || elfobj.machine != ElfMach386 || hdr.Ident[4] != ElfClass32 {
			Errorf(nil, "%s: elf object but not 386", pn)
			return
		}

	case sys.PPC64:
		if elfobj.machine != ElfMachPower64 || hdr.Ident[4] != ElfClass64 {
			Errorf(nil, "%s: elf object but not ppc64", pn)
			return
		}

	case sys.S390X:
		if elfobj.machine != ElfMachS390 || hdr.Ident[4] != ElfClass64 {
			Errorf(nil, "%s: elf object but not s390x", pn)
			return
		}
	}

	// load section list into memory.
	elfobj.sect = make([]ElfSect, elfobj.shnum)

	elfobj.nsect = uint(elfobj.shnum)
	for i := 0; uint(i) < elfobj.nsect; i++ {
		if f.Seek(int64(uint64(base)+elfobj.shoff+uint64(int64(i)*int64(elfobj.shentsize))), 0) < 0 {
			goto bad
		}
		sect = &elfobj.sect[i]
		if is64 != 0 {
			var b ElfSectBytes64

			if err = binary.Read(f, e, &b); err != nil {
				goto bad
			}

			sect.nameoff = e.Uint32(b.Name[:])
			sect.type_ = e.Uint32(b.Type[:])
			sect.flags = e.Uint64(b.Flags[:])
			sect.addr = e.Uint64(b.Addr[:])
			sect.off = e.Uint64(b.Off[:])
			sect.size = e.Uint64(b.Size[:])
			sect.link = e.Uint32(b.Link[:])
			sect.info = e.Uint32(b.Info[:])
			sect.align = e.Uint64(b.Align[:])
			sect.entsize = e.Uint64(b.Entsize[:])
		} else {
			var b ElfSectBytes

			if err = binary.Read(f, e, &b); err != nil {
				goto bad
			}

			sect.nameoff = e.Uint32(b.Name[:])
			sect.type_ = e.Uint32(b.Type[:])
			sect.flags = uint64(e.Uint32(b.Flags[:]))
			sect.addr = uint64(e.Uint32(b.Addr[:]))
			sect.off = uint64(e.Uint32(b.Off[:]))
			sect.size = uint64(e.Uint32(b.Size[:]))
			sect.link = e.Uint32(b.Link[:])
			sect.info = e.Uint32(b.Info[:])
			sect.align = uint64(e.Uint32(b.Align[:]))
			sect.entsize = uint64(e.Uint32(b.Entsize[:]))
		}
	}

	// read section string table and translate names
	if elfobj.shstrndx >= uint32(elfobj.nsect) {
		err = fmt.Errorf("shstrndx out of range %d >= %d", elfobj.shstrndx, elfobj.nsect)
		goto bad
	}

	sect = &elfobj.sect[elfobj.shstrndx]
	if err = elfmap(elfobj, sect); err != nil {
		goto bad
	}
	for i := 0; uint(i) < elfobj.nsect; i++ {
		if elfobj.sect[i].nameoff != 0 {
			elfobj.sect[i].name = cstring(sect.base[elfobj.sect[i].nameoff:])
		}
	}

	// load string table for symbols into memory.
	elfobj.symtab = section(elfobj, ".symtab")

	if elfobj.symtab == nil {
		// our work is done here - no symbols means nothing can refer to this file
		return
	}

	if elfobj.symtab.link <= 0 || elfobj.symtab.link >= uint32(elfobj.nsect) {
		Errorf(nil, "%s: elf object has symbol table with invalid string table link", pn)
		return
	}

	elfobj.symstr = &elfobj.sect[elfobj.symtab.link]
	if is64 != 0 {
		elfobj.nsymtab = int(elfobj.symtab.size / ELF64SYMSIZE)
	} else {
		elfobj.nsymtab = int(elfobj.symtab.size / ELF32SYMSIZE)
	}

	if err = elfmap(elfobj, elfobj.symtab); err != nil {
		goto bad
	}
	if err = elfmap(elfobj, elfobj.symstr); err != nil {
		goto bad
	}

	// load text and data segments into memory.
	// they are not as small as the section lists, but we'll need
	// the memory anyway for the symbol images, so we might
	// as well use one large chunk.

	// create symbols for elfmapped sections
	for i := 0; uint(i) < elfobj.nsect; i++ {
		sect = &elfobj.sect[i]
		if sect.type_ == SHT_ARM_ATTRIBUTES && sect.name == ".ARM.attributes" {
			if err = elfmap(elfobj, sect); err != nil {
				goto bad
			}
			parseArmAttributes(ctxt, e, sect.base[:sect.size])
		}
		if (sect.type_ != ElfSectProgbits && sect.type_ != ElfSectNobits) || sect.flags&ElfSectFlagAlloc == 0 {
			continue
		}
		if sect.type_ != ElfSectNobits {
			if err = elfmap(elfobj, sect); err != nil {
				goto bad
			}
		}

		name = fmt.Sprintf("%s(%s)", pkg, sect.name)
		s = ctxt.Syms.Lookup(name, localSymVersion)

		switch int(sect.flags) & (ElfSectFlagAlloc | ElfSectFlagWrite | ElfSectFlagExec) {
		default:
			err = fmt.Errorf("unexpected flags for ELF section %s", sect.name)
			goto bad

		case ElfSectFlagAlloc:
			s.Type = obj.SRODATA

		case ElfSectFlagAlloc + ElfSectFlagWrite:
			if sect.type_ == ElfSectNobits {
				s.Type = obj.SNOPTRBSS
			} else {
				s.Type = obj.SNOPTRDATA
			}

		case ElfSectFlagAlloc + ElfSectFlagExec:
			s.Type = obj.STEXT
		}

		if sect.name == ".got" || sect.name == ".toc" {
			s.Type = obj.SELFGOT
		}
		if sect.type_ == ElfSectProgbits {
			s.P = sect.base
			s.P = s.P[:sect.size]
		}

		s.Size = int64(sect.size)
		s.Align = int32(sect.align)
		sect.sym = s
	}

	// enter sub-symbols into symbol table.
	// symbol 0 is the null symbol.
	symbols = make([]*Symbol, elfobj.nsymtab)

	for i := 1; i < elfobj.nsymtab; i++ {
		if err = readelfsym(ctxt, elfobj, i, &sym, 1, localSymVersion); err != nil {
			goto bad
		}
		symbols[i] = sym.sym
		if sym.type_ != ElfSymTypeFunc && sym.type_ != ElfSymTypeObject && sym.type_ != ElfSymTypeNone {
			continue
		}
		if sym.shndx == ElfSymShnCommon {
			s = sym.sym
			if uint64(s.Size) < sym.size {
				s.Size = int64(sym.size)
			}
			if s.Type == 0 || s.Type == obj.SXREF {
				s.Type = obj.SNOPTRBSS
			}
			continue
		}

		if uint(sym.shndx) >= elfobj.nsect || sym.shndx == 0 {
			continue
		}

		// even when we pass needSym == 1 to readelfsym, it might still return nil to skip some unwanted symbols
		if sym.sym == nil {
			continue
		}
		sect = &elfobj.sect[sym.shndx]
		if sect.sym == nil {
			if strings.HasPrefix(sym.name, ".Linfo_string") { // clang does this
				continue
			}

			if sym.name == "" && sym.type_ == 0 && sect.name == ".debug_str" {
				// This reportedly happens with clang 3.7 on ARM.
				// See issue 13139.
				continue
			}

			if strings.HasPrefix(sym.name, ".LASF") { // gcc on s390x does this
				continue
			}
			Errorf(sym.sym, "%s: sym#%d: ignoring symbol in section %d (type %d)", pn, i, sym.shndx, sym.type_)
			continue
		}

		s = sym.sym
		if s.Outer != nil {
			if s.Attr.DuplicateOK() {
				continue
			}
			Exitf("%s: duplicate symbol reference: %s in both %s and %s", pn, s.Name, s.Outer.Name, sect.sym.Name)
		}

		s.Sub = sect.sym.Sub
		sect.sym.Sub = s
		s.Type = sect.sym.Type | s.Type&^obj.SMASK | obj.SSUB
		if !s.Attr.CgoExportDynamic() {
			s.Dynimplib = "" // satisfy dynimport
		}
		s.Value = int64(sym.value)
		s.Size = int64(sym.size)
		s.Outer = sect.sym
		if sect.sym.Type == obj.STEXT {
			if s.Attr.External() && !s.Attr.DuplicateOK() {
				Errorf(s, "%s: duplicate symbol definition", pn)
			}
			s.Attr |= AttrExternal
		}

		if elfobj.machine == ElfMachPower64 {
			flag = int(sym.other) >> 5
			if 2 <= flag && flag <= 6 {
				s.Localentry = 1 << uint(flag-2)
			} else if flag == 7 {
				Errorf(s, "%s: invalid sym.other 0x%x", pn, sym.other)
			}
		}
	}

	// Sort outer lists by address, adding to textp.
	// This keeps textp in increasing address order.
	for i := 0; uint(i) < elfobj.nsect; i++ {
		s = elfobj.sect[i].sym
		if s == nil {
			continue
		}
		if s.Sub != nil {
			s.Sub = listsort(s.Sub)
		}
		if s.Type == obj.STEXT {
			if s.Attr.OnList() {
				log.Fatalf("symbol %s listed multiple times", s.Name)
			}
			s.Attr |= AttrOnList
			ctxt.Textp = append(ctxt.Textp, s)
			for s = s.Sub; s != nil; s = s.Sub {
				if s.Attr.OnList() {
					log.Fatalf("symbol %s listed multiple times", s.Name)
				}
				s.Attr |= AttrOnList
				ctxt.Textp = append(ctxt.Textp, s)
			}
		}
	}

	// load relocations
	for i := 0; uint(i) < elfobj.nsect; i++ {
		rsect = &elfobj.sect[i]
		if rsect.type_ != ElfSectRela && rsect.type_ != ElfSectRel {
			continue
		}
		if rsect.info >= uint32(elfobj.nsect) || elfobj.sect[rsect.info].base == nil {
			continue
		}
		sect = &elfobj.sect[rsect.info]
		if err = elfmap(elfobj, rsect); err != nil {
			goto bad
		}
		rela = 0
		if rsect.type_ == ElfSectRela {
			rela = 1
		}
		n = int(rsect.size / uint64(4+4*is64) / uint64(2+rela))
		r = make([]Reloc, n)
		p = rsect.base
		for j = 0; j < n; j++ {
			add = 0
			rp = &r[j]
			if is64 != 0 {
				// 64-bit rel/rela
				rp.Off = int32(e.Uint64(p))

				p = p[8:]
				info = e.Uint64(p)
				p = p[8:]
				if rela != 0 {
					add = e.Uint64(p)
					p = p[8:]
				}
			} else {
				// 32-bit rel/rela
				rp.Off = int32(e.Uint32(p))

				p = p[4:]
				info = uint64(e.Uint32(p))
				info = info>>8<<32 | info&0xff // convert to 64-bit info
				p = p[4:]
				if rela != 0 {
					add = uint64(e.Uint32(p))
					p = p[4:]
				}
			}

			if info&0xffffffff == 0 { // skip R_*_NONE relocation
				j--
				n--
				continue
			}

			if info>>32 == 0 { // absolute relocation, don't bother reading the null symbol
				rp.Sym = nil
			} else {
				if err = readelfsym(ctxt, elfobj, int(info>>32), &sym, 0, 0); err != nil {
					goto bad
				}
				sym.sym = symbols[info>>32]
				if sym.sym == nil {
					err = fmt.Errorf("%s#%d: reloc of invalid sym #%d %s shndx=%d type=%d", sect.sym.Name, j, int(info>>32), sym.name, sym.shndx, sym.type_)
					goto bad
				}

				rp.Sym = sym.sym
			}

			rp.Type = 256 + obj.RelocType(info)
			rp.Siz = relSize(ctxt, pn, uint32(info))
			if rela != 0 {
				rp.Add = int64(add)
			} else {
				// load addend from image
				if rp.Siz == 4 {
					rp.Add = int64(e.Uint32(sect.base[rp.Off:]))
				} else if rp.Siz == 8 {
					rp.Add = int64(e.Uint64(sect.base[rp.Off:]))
				} else {
					Errorf(nil, "invalid rela size %d", rp.Siz)
				}
			}

			if rp.Siz == 2 {
				rp.Add = int64(int16(rp.Add))
			}
			if rp.Siz == 4 {
				rp.Add = int64(int32(rp.Add))
			}
		}

		//print("rel %s %d %d %s %#llx\n", sect->sym->name, rp->type, rp->siz, rp->sym->name, rp->add);
		sort.Sort(rbyoff(r[:n]))
		// just in case

		s = sect.sym
		s.R = r
		s.R = s.R[:n]
	}

	return

bad:
	Errorf(nil, "%s: malformed elf file: %v", pn, err)
}
コード例 #4
0
ファイル: ldpe.go プロジェクト: achanda/go
func ldpeError(ctxt *Link, input *bio.Reader, pkg string, length int64, pn string) error {
	if ctxt.Debugvlog != 0 {
		ctxt.Logf("%5.2f ldpe %s\n", obj.Cputime(), pn)
	}

	localSymVersion := ctxt.Syms.IncVersion()

	sectsyms := make(map[*pe.Section]*Symbol)
	sectdata := make(map[*pe.Section][]byte)

	// Some input files are archives containing multiple of
	// object files, and pe.NewFile seeks to the start of
	// input file and get confused. Create section reader
	// to stop pe.NewFile looking before current position.
	sr := io.NewSectionReader((*peBiobuf)(input), input.Offset(), 1<<63-1)

	// TODO: replace pe.NewFile with pe.Load (grep for "add Load function" in debug/pe for details)
	f, err := pe.NewFile(sr)
	if err != nil {
		return err
	}
	defer f.Close()

	// TODO return error if found .cormeta

	// create symbols for mapped sections
	for _, sect := range f.Sections {
		if sect.Characteristics&IMAGE_SCN_MEM_DISCARDABLE != 0 {
			continue
		}

		if sect.Characteristics&(IMAGE_SCN_CNT_CODE|IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
			// This has been seen for .idata sections, which we
			// want to ignore. See issues 5106 and 5273.
			continue
		}

		data, err := sect.Data()
		if err != nil {
			return err
		}
		sectdata[sect] = data

		name := fmt.Sprintf("%s(%s)", pkg, sect.Name)
		s := ctxt.Syms.Lookup(name, localSymVersion)

		switch sect.Characteristics & (IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE | IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE) {
		case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ: //.rdata
			s.Type = obj.SRODATA

		case IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE: //.bss
			s.Type = obj.SNOPTRBSS

		case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE: //.data
			s.Type = obj.SNOPTRDATA

		case IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE | IMAGE_SCN_MEM_READ: //.text
			s.Type = obj.STEXT

		default:
			return fmt.Errorf("unexpected flags %#06x for PE section %s", sect.Characteristics, sect.Name)
		}

		s.P = data
		s.Size = int64(len(data))
		sectsyms[sect] = s
		if sect.Name == ".rsrc" {
			setpersrc(ctxt, s)
		}
	}

	// load relocations
	for _, rsect := range f.Sections {
		if _, found := sectsyms[rsect]; !found {
			continue
		}
		if rsect.NumberOfRelocations == 0 {
			continue
		}
		if rsect.Characteristics&IMAGE_SCN_MEM_DISCARDABLE != 0 {
			continue
		}
		if rsect.Characteristics&(IMAGE_SCN_CNT_CODE|IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
			// This has been seen for .idata sections, which we
			// want to ignore. See issues 5106 and 5273.
			continue
		}

		rs := make([]Reloc, rsect.NumberOfRelocations)
		for j, r := range rsect.Relocs {
			rp := &rs[j]
			if int(r.SymbolTableIndex) >= len(f.COFFSymbols) {
				return fmt.Errorf("relocation number %d symbol index idx=%d cannot be large then number of symbols %d", j, r.SymbolTableIndex, len(f.COFFSymbols))
			}
			pesym := &f.COFFSymbols[r.SymbolTableIndex]
			gosym, err := readpesym(ctxt, f, pesym, sectsyms, localSymVersion)
			if err != nil {
				return err
			}
			if gosym == nil {
				name, err := pesym.FullName(f.StringTable)
				if err != nil {
					name = string(pesym.Name[:])
				}
				return fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
			}

			rp.Sym = gosym
			rp.Siz = 4
			rp.Off = int32(r.VirtualAddress)
			switch r.Type {
			default:
				Errorf(sectsyms[rsect], "%s: unknown relocation type %d;", pn, r.Type)
				fallthrough

			case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
				IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
				IMAGE_REL_AMD64_ADDR32NB:
				rp.Type = obj.R_PCREL

				rp.Add = int64(int32(Le32(sectdata[rsect][rp.Off:])))

			case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
				rp.Type = obj.R_ADDR

				// load addend from image
				rp.Add = int64(int32(Le32(sectdata[rsect][rp.Off:])))

			case IMAGE_REL_AMD64_ADDR64: // R_X86_64_64
				rp.Siz = 8

				rp.Type = obj.R_ADDR

				// load addend from image
				rp.Add = int64(Le64(sectdata[rsect][rp.Off:]))
			}

			// ld -r could generate multiple section symbols for the
			// same section but with different values, we have to take
			// that into account
			if issect(pesym) {
				rp.Add += int64(pesym.Value)
			}
		}

		sort.Sort(rbyoff(rs[:rsect.NumberOfRelocations]))

		s := sectsyms[rsect]
		s.R = rs
		s.R = s.R[:rsect.NumberOfRelocations]
	}

	// enter sub-symbols into symbol table.
	for i, numaux := 0, 0; i < len(f.COFFSymbols); i += numaux + 1 {
		pesym := &f.COFFSymbols[i]

		numaux = int(pesym.NumberOfAuxSymbols)

		name, err := pesym.FullName(f.StringTable)
		if err != nil {
			return err
		}
		if name == "" {
			continue
		}
		if issect(pesym) {
			continue
		}
		if int(pesym.SectionNumber) > len(f.Sections) {
			continue
		}
		if pesym.SectionNumber == IMAGE_SYM_DEBUG {
			continue
		}
		var sect *pe.Section
		if pesym.SectionNumber > 0 {
			sect = f.Sections[pesym.SectionNumber-1]
			if _, found := sectsyms[sect]; !found {
				continue
			}
		}

		s, err := readpesym(ctxt, f, pesym, sectsyms, localSymVersion)
		if err != nil {
			return err
		}

		if pesym.SectionNumber == 0 { // extern
			if s.Type == obj.SDYNIMPORT {
				s.Plt = -2 // flag for dynimport in PE object files.
			}
			if s.Type == obj.SXREF && pesym.Value > 0 { // global data
				s.Type = obj.SNOPTRDATA
				s.Size = int64(pesym.Value)
			}

			continue
		} else if pesym.SectionNumber > 0 && int(pesym.SectionNumber) <= len(f.Sections) {
			sect = f.Sections[pesym.SectionNumber-1]
			if _, found := sectsyms[sect]; !found {
				Errorf(s, "%s: missing sect.sym", pn)
			}
		} else {
			Errorf(s, "%s: sectnum < 0!", pn)
		}

		if sect == nil {
			return nil
		}

		if s.Outer != nil {
			if s.Attr.DuplicateOK() {
				continue
			}
			Exitf("%s: duplicate symbol reference: %s in both %s and %s", pn, s.Name, s.Outer.Name, sectsyms[sect].Name)
		}

		sectsym := sectsyms[sect]
		s.Sub = sectsym.Sub
		sectsym.Sub = s
		s.Type = sectsym.Type | obj.SSUB
		s.Value = int64(pesym.Value)
		s.Size = 4
		s.Outer = sectsym
		if sectsym.Type == obj.STEXT {
			if s.Attr.External() && !s.Attr.DuplicateOK() {
				Errorf(s, "%s: duplicate symbol definition", pn)
			}
			s.Attr |= AttrExternal
		}
	}

	// Sort outer lists by address, adding to textp.
	// This keeps textp in increasing address order.
	for _, sect := range f.Sections {
		s := sectsyms[sect]
		if s == nil {
			continue
		}
		if s.Sub != nil {
			s.Sub = listsort(s.Sub)
		}
		if s.Type == obj.STEXT {
			if s.Attr.OnList() {
				log.Fatalf("symbol %s listed multiple times", s.Name)
			}
			s.Attr |= AttrOnList
			ctxt.Textp = append(ctxt.Textp, s)
			for s = s.Sub; s != nil; s = s.Sub {
				if s.Attr.OnList() {
					log.Fatalf("symbol %s listed multiple times", s.Name)
				}
				s.Attr |= AttrOnList
				ctxt.Textp = append(ctxt.Textp, s)
			}
		}
	}

	return nil
}
コード例 #5
0
ファイル: ldmacho.go プロジェクト: Xiahl1990/go
func ldmacho(f *bio.Reader, pkg string, length int64, pn string) {
	var err error
	var j int
	var is64 bool
	var secaddr uint64
	var hdr [7 * 4]uint8
	var cmdp []byte
	var dat []byte
	var ncmd uint32
	var cmdsz uint32
	var ty uint32
	var sz uint32
	var off uint32
	var m *LdMachoObj
	var e binary.ByteOrder
	var sect *LdMachoSect
	var rel *LdMachoRel
	var rpi int
	var s *LSym
	var s1 *LSym
	var outer *LSym
	var c *LdMachoCmd
	var symtab *LdMachoSymtab
	var dsymtab *LdMachoDysymtab
	var sym *LdMachoSym
	var r []Reloc
	var rp *Reloc
	var name string

	Ctxt.IncVersion()
	base := f.Offset()
	if _, err := io.ReadFull(f, hdr[:]); err != nil {
		goto bad
	}

	if binary.BigEndian.Uint32(hdr[:])&^1 == 0xFEEDFACE {
		e = binary.BigEndian
	} else if binary.LittleEndian.Uint32(hdr[:])&^1 == 0xFEEDFACE {
		e = binary.LittleEndian
	} else {
		err = fmt.Errorf("bad magic - not mach-o file")
		goto bad
	}

	is64 = e.Uint32(hdr[:]) == 0xFEEDFACF
	ncmd = e.Uint32(hdr[4*4:])
	cmdsz = e.Uint32(hdr[5*4:])
	if ncmd > 0x10000 || cmdsz >= 0x01000000 {
		err = fmt.Errorf("implausible mach-o header ncmd=%d cmdsz=%d", ncmd, cmdsz)
		goto bad
	}

	if is64 {
		f.Seek(4, 1) // skip reserved word in header
	}

	m = new(LdMachoObj)

	m.f = f
	m.e = e
	m.cputype = uint(e.Uint32(hdr[1*4:]))
	m.subcputype = uint(e.Uint32(hdr[2*4:]))
	m.filetype = e.Uint32(hdr[3*4:])
	m.ncmd = uint(ncmd)
	m.flags = e.Uint32(hdr[6*4:])
	m.is64 = is64
	m.base = base
	m.length = length
	m.name = pn

	switch SysArch.Family {
	default:
		Diag("%s: mach-o %s unimplemented", pn, SysArch.Name)
		return

	case sys.AMD64:
		if e != binary.LittleEndian || m.cputype != LdMachoCpuAmd64 {
			Diag("%s: mach-o object but not amd64", pn)
			return
		}

	case sys.I386:
		if e != binary.LittleEndian || m.cputype != LdMachoCpu386 {
			Diag("%s: mach-o object but not 386", pn)
			return
		}
	}

	m.cmd = make([]LdMachoCmd, ncmd)
	off = uint32(len(hdr))
	cmdp = make([]byte, cmdsz)
	if _, err2 := io.ReadFull(f, cmdp); err2 != nil {
		err = fmt.Errorf("reading cmds: %v", err)
		goto bad
	}

	// read and parse load commands
	c = nil

	symtab = nil
	dsymtab = nil

	for i := 0; uint32(i) < ncmd; i++ {
		ty = e.Uint32(cmdp)
		sz = e.Uint32(cmdp[4:])
		m.cmd[i].off = off
		unpackcmd(cmdp, m, &m.cmd[i], uint(ty), uint(sz))
		cmdp = cmdp[sz:]
		off += sz
		if ty == LdMachoCmdSymtab {
			if symtab != nil {
				err = fmt.Errorf("multiple symbol tables")
				goto bad
			}

			symtab = &m.cmd[i].sym
			macholoadsym(m, symtab)
		}

		if ty == LdMachoCmdDysymtab {
			dsymtab = &m.cmd[i].dsym
			macholoaddsym(m, dsymtab)
		}

		if (is64 && ty == LdMachoCmdSegment64) || (!is64 && ty == LdMachoCmdSegment) {
			if c != nil {
				err = fmt.Errorf("multiple load commands")
				goto bad
			}

			c = &m.cmd[i]
		}
	}

	// load text and data segments into memory.
	// they are not as small as the load commands, but we'll need
	// the memory anyway for the symbol images, so we might
	// as well use one large chunk.
	if c == nil {
		err = fmt.Errorf("no load command")
		goto bad
	}

	if symtab == nil {
		// our work is done here - no symbols means nothing can refer to this file
		return
	}

	if int64(c.seg.fileoff+c.seg.filesz) >= length {
		err = fmt.Errorf("load segment out of range")
		goto bad
	}

	dat = make([]byte, c.seg.filesz)
	if f.Seek(m.base+int64(c.seg.fileoff), 0) < 0 {
		err = fmt.Errorf("cannot load object data: %v", err)
		goto bad
	}
	if _, err2 := io.ReadFull(f, dat); err2 != nil {
		err = fmt.Errorf("cannot load object data: %v", err)
		goto bad
	}

	for i := 0; uint32(i) < c.seg.nsect; i++ {
		sect = &c.seg.sect[i]
		if sect.segname != "__TEXT" && sect.segname != "__DATA" {
			continue
		}
		if sect.name == "__eh_frame" {
			continue
		}
		name = fmt.Sprintf("%s(%s/%s)", pkg, sect.segname, sect.name)
		s = Linklookup(Ctxt, name, Ctxt.Version)
		if s.Type != 0 {
			err = fmt.Errorf("duplicate %s/%s", sect.segname, sect.name)
			goto bad
		}

		if sect.flags&0xff == 1 { // S_ZEROFILL
			s.P = make([]byte, sect.size)
		} else {
			s.P = dat[sect.addr-c.seg.vmaddr:][:sect.size]
		}
		s.Size = int64(len(s.P))

		if sect.segname == "__TEXT" {
			if sect.name == "__text" {
				s.Type = obj.STEXT
			} else {
				s.Type = obj.SRODATA
			}
		} else {
			if sect.name == "__bss" {
				s.Type = obj.SNOPTRBSS
				s.P = s.P[:0]
			} else {
				s.Type = obj.SNOPTRDATA
			}
		}

		sect.sym = s
	}

	// enter sub-symbols into symbol table.
	// have to guess sizes from next symbol.
	for i := 0; uint32(i) < symtab.nsym; i++ {
		sym = &symtab.sym[i]
		if sym.type_&N_STAB != 0 {
			continue
		}

		// TODO: check sym->type against outer->type.
		name = sym.name

		if name[0] == '_' && name[1] != '\x00' {
			name = name[1:]
		}
		v := 0
		if sym.type_&N_EXT == 0 {
			v = Ctxt.Version
		}
		s = Linklookup(Ctxt, name, v)
		if sym.type_&N_EXT == 0 {
			s.Attr |= AttrDuplicateOK
		}
		sym.sym = s
		if sym.sectnum == 0 { // undefined
			continue
		}
		if uint32(sym.sectnum) > c.seg.nsect {
			err = fmt.Errorf("reference to invalid section %d", sym.sectnum)
			goto bad
		}

		sect = &c.seg.sect[sym.sectnum-1]
		outer = sect.sym
		if outer == nil {
			err = fmt.Errorf("reference to invalid section %s/%s", sect.segname, sect.name)
			continue
		}

		if s.Outer != nil {
			if s.Attr.DuplicateOK() {
				continue
			}
			Exitf("%s: duplicate symbol reference: %s in both %s and %s", pn, s.Name, s.Outer.Name, sect.sym.Name)
		}

		s.Type = outer.Type | obj.SSUB
		s.Sub = outer.Sub
		outer.Sub = s
		s.Outer = outer
		s.Value = int64(sym.value - sect.addr)
		if !s.Attr.CgoExportDynamic() {
			s.Dynimplib = "" // satisfy dynimport
		}
		if outer.Type == obj.STEXT {
			if s.Attr.External() && !s.Attr.DuplicateOK() {
				Diag("%s: duplicate definition of %s", pn, s.Name)
			}
			s.Attr |= AttrExternal
		}

		sym.sym = s
	}

	// Sort outer lists by address, adding to textp.
	// This keeps textp in increasing address order.
	for i := 0; uint32(i) < c.seg.nsect; i++ {
		sect = &c.seg.sect[i]
		s = sect.sym
		if s == nil {
			continue
		}
		if s.Sub != nil {
			s.Sub = listsort(s.Sub, valuecmp, listsubp)

			// assign sizes, now that we know symbols in sorted order.
			for s1 = s.Sub; s1 != nil; s1 = s1.Sub {
				if s1.Sub != nil {
					s1.Size = s1.Sub.Value - s1.Value
				} else {
					s1.Size = s.Value + s.Size - s1.Value
				}
			}
		}

		if s.Type == obj.STEXT {
			if s.Attr.OnList() {
				log.Fatalf("symbol %s listed multiple times", s.Name)
			}
			s.Attr |= AttrOnList
			Ctxt.Textp = append(Ctxt.Textp, s)
			for s1 = s.Sub; s1 != nil; s1 = s1.Sub {
				if s1.Attr.OnList() {
					log.Fatalf("symbol %s listed multiple times", s1.Name)
				}
				s1.Attr |= AttrOnList
				Ctxt.Textp = append(Ctxt.Textp, s1)
			}
		}
	}

	// load relocations
	for i := 0; uint32(i) < c.seg.nsect; i++ {
		sect = &c.seg.sect[i]
		s = sect.sym
		if s == nil {
			continue
		}
		macholoadrel(m, sect)
		if sect.rel == nil {
			continue
		}
		r = make([]Reloc, sect.nreloc)
		rpi = 0
	Reloc:
		for j = 0; uint32(j) < sect.nreloc; j++ {
			rp = &r[rpi]
			rel = &sect.rel[j]
			if rel.scattered != 0 {
				if SysArch.Family != sys.I386 {
					// mach-o only uses scattered relocation on 32-bit platforms
					Diag("unexpected scattered relocation")
					continue
				}

				// on 386, rewrite scattered 4/1 relocation and some
				// scattered 2/1 relocation into the pseudo-pc-relative
				// reference that it is.
				// assume that the second in the pair is in this section
				// and use that as the pc-relative base.
				if uint32(j+1) >= sect.nreloc {
					err = fmt.Errorf("unsupported scattered relocation %d", int(rel.type_))
					goto bad
				}

				if sect.rel[j+1].scattered == 0 || sect.rel[j+1].type_ != 1 || (rel.type_ != 4 && rel.type_ != 2) || uint64(sect.rel[j+1].value) < sect.addr || uint64(sect.rel[j+1].value) >= sect.addr+sect.size {
					err = fmt.Errorf("unsupported scattered relocation %d/%d", int(rel.type_), int(sect.rel[j+1].type_))
					goto bad
				}

				rp.Siz = rel.length
				rp.Off = int32(rel.addr)

				// NOTE(rsc): I haven't worked out why (really when)
				// we should ignore the addend on a
				// scattered relocation, but it seems that the
				// common case is we ignore it.
				// It's likely that this is not strictly correct
				// and that the math should look something
				// like the non-scattered case below.
				rp.Add = 0

				// want to make it pc-relative aka relative to rp->off+4
				// but the scatter asks for relative to off = sect->rel[j+1].value - sect->addr.
				// adjust rp->add accordingly.
				rp.Type = obj.R_PCREL

				rp.Add += int64(uint64(int64(rp.Off)+4) - (uint64(sect.rel[j+1].value) - sect.addr))

				// now consider the desired symbol.
				// find the section where it lives.
				var ks *LdMachoSect
				for k := 0; uint32(k) < c.seg.nsect; k++ {
					ks = &c.seg.sect[k]
					if ks.addr <= uint64(rel.value) && uint64(rel.value) < ks.addr+ks.size {
						if ks.sym != nil {
							rp.Sym = ks.sym
							rp.Add += int64(uint64(rel.value) - ks.addr)
						} else if ks.segname == "__IMPORT" && ks.name == "__pointers" {
							// handle reference to __IMPORT/__pointers.
							// how much worse can this get?
							// why are we supporting 386 on the mac anyway?
							rp.Type = 512 + MACHO_FAKE_GOTPCREL

							// figure out which pointer this is a reference to.
							k = int(uint64(ks.res1) + (uint64(rel.value)-ks.addr)/4)

							// load indirect table for __pointers
							// fetch symbol number
							if dsymtab == nil || k < 0 || uint32(k) >= dsymtab.nindirectsyms || dsymtab.indir == nil {
								err = fmt.Errorf("invalid scattered relocation: indirect symbol reference out of range")
								goto bad
							}

							k = int(dsymtab.indir[k])
							if k < 0 || uint32(k) >= symtab.nsym {
								err = fmt.Errorf("invalid scattered relocation: symbol reference out of range")
								goto bad
							}

							rp.Sym = symtab.sym[k].sym
						} else {
							err = fmt.Errorf("unsupported scattered relocation: reference to %s/%s", ks.segname, ks.name)
							goto bad
						}

						rpi++

						// skip #1 of 2 rel; continue skips #2 of 2.
						j++

						continue Reloc
					}
				}

				err = fmt.Errorf("unsupported scattered relocation: invalid address %#x", rel.addr)
				goto bad

			}

			rp.Siz = rel.length
			rp.Type = 512 + (int32(rel.type_) << 1) + int32(rel.pcrel)
			rp.Off = int32(rel.addr)

			// Handle X86_64_RELOC_SIGNED referencing a section (rel->extrn == 0).
			if SysArch.Family == sys.AMD64 && rel.extrn == 0 && rel.type_ == 1 {
				// Calculate the addend as the offset into the section.
				//
				// The rip-relative offset stored in the object file is encoded
				// as follows:
				//
				//    movsd	0x00000360(%rip),%xmm0
				//
				// To get the absolute address of the value this rip-relative address is pointing
				// to, we must add the address of the next instruction to it. This is done by
				// taking the address of the relocation and adding 4 to it (since the rip-relative
				// offset can at most be 32 bits long).  To calculate the offset into the section the
				// relocation is referencing, we subtract the vaddr of the start of the referenced
				// section found in the original object file.
				//
				// [For future reference, see Darwin's /usr/include/mach-o/x86_64/reloc.h]
				secaddr = c.seg.sect[rel.symnum-1].addr

				rp.Add = int64(uint64(int64(int32(e.Uint32(s.P[rp.Off:])))+int64(rp.Off)+4) - secaddr)
			} else {
				rp.Add = int64(int32(e.Uint32(s.P[rp.Off:])))
			}

			// For i386 Mach-O PC-relative, the addend is written such that
			// it *is* the PC being subtracted. Use that to make
			// it match our version of PC-relative.
			if rel.pcrel != 0 && SysArch.Family == sys.I386 {
				rp.Add += int64(rp.Off) + int64(rp.Siz)
			}
			if rel.extrn == 0 {
				if rel.symnum < 1 || rel.symnum > c.seg.nsect {
					err = fmt.Errorf("invalid relocation: section reference out of range %d vs %d", rel.symnum, c.seg.nsect)
					goto bad
				}

				rp.Sym = c.seg.sect[rel.symnum-1].sym
				if rp.Sym == nil {
					err = fmt.Errorf("invalid relocation: %s", c.seg.sect[rel.symnum-1].name)
					goto bad
				}

				// References to symbols in other sections
				// include that information in the addend.
				// We only care about the delta from the
				// section base.
				if SysArch.Family == sys.I386 {
					rp.Add -= int64(c.seg.sect[rel.symnum-1].addr)
				}
			} else {
				if rel.symnum >= symtab.nsym {
					err = fmt.Errorf("invalid relocation: symbol reference out of range")
					goto bad
				}

				rp.Sym = symtab.sym[rel.symnum].sym
			}

			rpi++
		}

		sort.Sort(rbyoff(r[:rpi]))
		s.R = r
		s.R = s.R[:rpi]
	}

	return

bad:
	Diag("%s: malformed mach-o file: %v", pn, err)
}
コード例 #6
0
ファイル: ldpe.go プロジェクト: SpiderOak/go
func ldpe(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
	if ctxt.Debugvlog != 0 {
		fmt.Fprintf(ctxt.Bso, "%5.2f ldpe %s\n", obj.Cputime(), pn)
	}

	var sect *PeSect
	ctxt.IncVersion()
	base := f.Offset()

	peobj := new(PeObj)
	peobj.f = f
	peobj.base = uint32(base)
	peobj.name = pn

	// read header
	var err error
	var j int
	var l uint32
	var name string
	var numaux int
	var r []Reloc
	var rp *Reloc
	var rsect *PeSect
	var s *Symbol
	var sym *PeSym
	var symbuf [18]uint8
	if err = binary.Read(f, binary.LittleEndian, &peobj.fh); err != nil {
		goto bad
	}

	// load section list
	peobj.sect = make([]PeSect, peobj.fh.NumberOfSections)

	peobj.nsect = uint(peobj.fh.NumberOfSections)
	for i := 0; i < int(peobj.fh.NumberOfSections); i++ {
		if err = binary.Read(f, binary.LittleEndian, &peobj.sect[i].sh); err != nil {
			goto bad
		}
		peobj.sect[i].size = uint64(peobj.sect[i].sh.SizeOfRawData)
		peobj.sect[i].name = cstring(peobj.sect[i].sh.Name[:])
	}

	// TODO return error if found .cormeta

	// load string table
	f.Seek(base+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(peobj.fh.NumberOfSymbols), 0)

	if _, err := io.ReadFull(f, symbuf[:4]); err != nil {
		goto bad
	}
	l = Le32(symbuf[:])
	peobj.snames = make([]byte, l)
	f.Seek(base+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(peobj.fh.NumberOfSymbols), 0)
	if _, err := io.ReadFull(f, peobj.snames); err != nil {
		goto bad
	}

	// rewrite section names if they start with /
	for i := 0; i < int(peobj.fh.NumberOfSections); i++ {
		if peobj.sect[i].name == "" {
			continue
		}
		if peobj.sect[i].name[0] != '/' {
			continue
		}
		n, _ := strconv.Atoi(peobj.sect[i].name[1:])
		peobj.sect[i].name = cstring(peobj.snames[n:])
	}

	// read symbols
	peobj.pesym = make([]PeSym, peobj.fh.NumberOfSymbols)

	peobj.npesym = uint(peobj.fh.NumberOfSymbols)
	f.Seek(base+int64(peobj.fh.PointerToSymbolTable), 0)
	for i := 0; uint32(i) < peobj.fh.NumberOfSymbols; i += numaux + 1 {
		f.Seek(base+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(i), 0)
		if _, err := io.ReadFull(f, symbuf[:]); err != nil {
			goto bad
		}

		if (symbuf[0] == 0) && (symbuf[1] == 0) && (symbuf[2] == 0) && (symbuf[3] == 0) {
			l = Le32(symbuf[4:])
			peobj.pesym[i].name = cstring(peobj.snames[l:]) // sym name length <= 8
		} else {
			peobj.pesym[i].name = cstring(symbuf[:8])
		}

		peobj.pesym[i].value = Le32(symbuf[8:])
		peobj.pesym[i].sectnum = Le16(symbuf[12:])
		peobj.pesym[i].sclass = symbuf[16]
		peobj.pesym[i].aux = symbuf[17]
		peobj.pesym[i].type_ = Le16(symbuf[14:])
		numaux = int(peobj.pesym[i].aux)
		if numaux < 0 {
			numaux = 0
		}
	}

	// create symbols for mapped sections
	for i := 0; uint(i) < peobj.nsect; i++ {
		sect = &peobj.sect[i]
		if sect.sh.Characteristics&IMAGE_SCN_MEM_DISCARDABLE != 0 {
			continue
		}

		if sect.sh.Characteristics&(IMAGE_SCN_CNT_CODE|IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
			// This has been seen for .idata sections, which we
			// want to ignore. See issues 5106 and 5273.
			continue
		}

		if pemap(peobj, sect) < 0 {
			goto bad
		}

		name = fmt.Sprintf("%s(%s)", pkg, sect.name)
		s = Linklookup(ctxt, name, ctxt.Version)

		switch sect.sh.Characteristics & (IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE | IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE) {
		case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ: //.rdata
			s.Type = obj.SRODATA

		case IMAGE_SCN_CNT_UNINITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE: //.bss
			s.Type = obj.SNOPTRBSS

		case IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE: //.data
			s.Type = obj.SNOPTRDATA

		case IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE | IMAGE_SCN_MEM_READ: //.text
			s.Type = obj.STEXT

		default:
			err = fmt.Errorf("unexpected flags %#06x for PE section %s", sect.sh.Characteristics, sect.name)
			goto bad
		}

		s.P = sect.base
		s.P = s.P[:sect.size]
		s.Size = int64(sect.size)
		sect.sym = s
		if sect.name == ".rsrc" {
			setpersrc(ctxt, sect.sym)
		}
	}

	// load relocations
	for i := 0; uint(i) < peobj.nsect; i++ {
		rsect = &peobj.sect[i]
		if rsect.sym == nil || rsect.sh.NumberOfRelocations == 0 {
			continue
		}
		if rsect.sh.Characteristics&IMAGE_SCN_MEM_DISCARDABLE != 0 {
			continue
		}
		if sect.sh.Characteristics&(IMAGE_SCN_CNT_CODE|IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0 {
			// This has been seen for .idata sections, which we
			// want to ignore. See issues 5106 and 5273.
			continue
		}

		r = make([]Reloc, rsect.sh.NumberOfRelocations)
		f.Seek(int64(peobj.base)+int64(rsect.sh.PointerToRelocations), 0)
		for j = 0; j < int(rsect.sh.NumberOfRelocations); j++ {
			rp = &r[j]
			if _, err := io.ReadFull(f, symbuf[:10]); err != nil {
				goto bad
			}
			rva := Le32(symbuf[0:])
			symindex := Le32(symbuf[4:])
			type_ := Le16(symbuf[8:])
			if err = readpesym(ctxt, peobj, int(symindex), &sym); err != nil {
				goto bad
			}
			if sym.sym == nil {
				err = fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", sym.name, symindex, sym.type_)
				goto bad
			}

			rp.Sym = sym.sym
			rp.Siz = 4
			rp.Off = int32(rva)
			switch type_ {
			default:
				ctxt.Diag("%s: unknown relocation type %d;", pn, type_)
				fallthrough

			case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
				IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
				IMAGE_REL_AMD64_ADDR32NB:
				rp.Type = obj.R_PCREL

				rp.Add = int64(int32(Le32(rsect.base[rp.Off:])))

			case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
				rp.Type = obj.R_ADDR

				// load addend from image
				rp.Add = int64(int32(Le32(rsect.base[rp.Off:])))

			case IMAGE_REL_AMD64_ADDR64: // R_X86_64_64
				rp.Siz = 8

				rp.Type = obj.R_ADDR

				// load addend from image
				rp.Add = int64(Le64(rsect.base[rp.Off:]))
			}

			// ld -r could generate multiple section symbols for the
			// same section but with different values, we have to take
			// that into account
			if issect(&peobj.pesym[symindex]) {
				rp.Add += int64(peobj.pesym[symindex].value)
			}
		}

		sort.Sort(rbyoff(r[:rsect.sh.NumberOfRelocations]))

		s = rsect.sym
		s.R = r
		s.R = s.R[:rsect.sh.NumberOfRelocations]
	}

	// enter sub-symbols into symbol table.
	for i := 0; uint(i) < peobj.npesym; i++ {
		if peobj.pesym[i].name == "" {
			continue
		}
		if issect(&peobj.pesym[i]) {
			continue
		}
		if uint(peobj.pesym[i].sectnum) > peobj.nsect {
			continue
		}
		if peobj.pesym[i].sectnum > 0 {
			sect = &peobj.sect[peobj.pesym[i].sectnum-1]
			if sect.sym == nil {
				continue
			}
		}

		if err = readpesym(ctxt, peobj, i, &sym); err != nil {
			goto bad
		}

		s = sym.sym
		if sym.sectnum == 0 { // extern
			if s.Type == obj.SDYNIMPORT {
				s.Plt = -2 // flag for dynimport in PE object files.
			}
			if s.Type == obj.SXREF && sym.value > 0 { // global data
				s.Type = obj.SNOPTRDATA
				s.Size = int64(sym.value)
			}

			continue
		} else if sym.sectnum > 0 && uint(sym.sectnum) <= peobj.nsect {
			sect = &peobj.sect[sym.sectnum-1]
			if sect.sym == nil {
				ctxt.Diag("%s: %s sym == 0!", pn, s.Name)
			}
		} else {
			ctxt.Diag("%s: %s sectnum < 0!", pn, s.Name)
		}

		if sect == nil {
			return
		}

		if s.Outer != nil {
			if s.Attr.DuplicateOK() {
				continue
			}
			Exitf("%s: duplicate symbol reference: %s in both %s and %s", pn, s.Name, s.Outer.Name, sect.sym.Name)
		}

		s.Sub = sect.sym.Sub
		sect.sym.Sub = s
		s.Type = sect.sym.Type | obj.SSUB
		s.Value = int64(sym.value)
		s.Size = 4
		s.Outer = sect.sym
		if sect.sym.Type == obj.STEXT {
			if s.Attr.External() && !s.Attr.DuplicateOK() {
				ctxt.Diag("%s: duplicate definition of %s", pn, s.Name)
			}
			s.Attr |= AttrExternal
		}
	}

	// Sort outer lists by address, adding to textp.
	// This keeps textp in increasing address order.
	for i := 0; uint(i) < peobj.nsect; i++ {
		s = peobj.sect[i].sym
		if s == nil {
			continue
		}
		if s.Sub != nil {
			s.Sub = listsort(s.Sub)
		}
		if s.Type == obj.STEXT {
			if s.Attr.OnList() {
				log.Fatalf("symbol %s listed multiple times", s.Name)
			}
			s.Attr |= AttrOnList
			ctxt.Textp = append(ctxt.Textp, s)
			for s = s.Sub; s != nil; s = s.Sub {
				if s.Attr.OnList() {
					log.Fatalf("symbol %s listed multiple times", s.Name)
				}
				s.Attr |= AttrOnList
				ctxt.Textp = append(ctxt.Textp, s)
			}
		}
	}

	return

bad:
	ctxt.Diag("%s: malformed pe file: %v", pn, err)
}