예제 #1
0
파일: data.go 프로젝트: rsc/tmp
func reloc() {
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f reloc\n", obj.Cputime())
	}
	Bflush(&Bso)

	for s := Ctxt.Textp; s != nil; s = s.Next {
		relocsym(s)
	}
	for s := datap; s != nil; s = s.Next {
		relocsym(s)
	}
}
예제 #2
0
파일: data.go 프로젝트: rsc/tmp
func dynreloc() {
	// -d suppresses dynamic loader format, so we may as well not
	// compute these sections or mark their symbols as reachable.
	if Debug['d'] != 0 && HEADTYPE != obj.Hwindows {
		return
	}
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f reloc\n", obj.Cputime())
	}
	Bflush(&Bso)

	for s := Ctxt.Textp; s != nil; s = s.Next {
		dynrelocsym(s)
	}
	for s := datap; s != nil; s = s.Next {
		dynrelocsym(s)
	}
	if Iself {
		elfdynhash()
	}
}
예제 #3
0
파일: ld.go 프로젝트: rsc/tmp
/*
 * add library to library list.
 *	srcref: src file referring to package
 *	objref: object file referring to package
 *	file: object file, e.g., /home/rsc/go/pkg/container/vector.a
 *	pkg: package import path, e.g. container/vector
 */
func addlibpath(ctxt *Link, srcref string, objref string, file string, pkg string, shlibnamefile string) {
	for i := 0; i < len(ctxt.Library); i++ {
		if pkg == ctxt.Library[i].Pkg {
			return
		}
	}

	if ctxt.Debugvlog > 1 && ctxt.Bso != nil {
		fmt.Fprintf(ctxt.Bso, "%5.2f addlibpath: srcref: %s objref: %s file: %s pkg: %s shlibnamefile: %s\n", obj.Cputime(), srcref, objref, file, pkg, shlibnamefile)
	}

	ctxt.Library = append(ctxt.Library, Library{})
	l := &ctxt.Library[len(ctxt.Library)-1]
	l.Objref = objref
	l.Srcref = srcref
	l.File = file
	l.Pkg = pkg
	if shlibnamefile != "" {
		shlibbytes, err := ioutil.ReadFile(shlibnamefile)
		if err != nil {
			Diag("cannot read %s: %v", shlibnamefile, err)
		}
		l.Shlib = strings.TrimSpace(string(shlibbytes))
	}
}
예제 #4
0
파일: ldpe.go 프로젝트: rsc/tmp
func ldpe(f *Biobuf, pkg string, length int64, pn string) {
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f ldpe %s\n", obj.Cputime(), pn)
	}

	var sect *PeSect
	Ctxt.Version++
	base := int32(Boffset(f))

	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 *LSym
	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
	Bseek(f, int64(base)+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(peobj.fh.NumberOfSymbols), 0)

	if Bread(f, symbuf[:4]) != 4 {
		goto bad
	}
	l = Le32(symbuf[:])
	peobj.snames = make([]byte, l)
	Bseek(f, int64(base)+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(peobj.fh.NumberOfSymbols), 0)
	if Bread(f, peobj.snames) != len(peobj.snames) {
		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
		}
		l = uint32(obj.Atoi(peobj.sect[i].name[1:]))
		peobj.sect[i].name = cstring(peobj.snames[l:])
	}

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

	peobj.npesym = uint(peobj.fh.NumberOfSymbols)
	Bseek(f, int64(base)+int64(peobj.fh.PointerToSymbolTable), 0)
	for i := 0; uint32(i) < peobj.fh.NumberOfSymbols; i += numaux + 1 {
		Bseek(f, int64(base)+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(i), 0)
		if Bread(f, symbuf[:]) != len(symbuf) {
			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(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)
		Bseek(f, int64(peobj.base)+int64(rsect.sh.PointerToRelocations), 0)
		for j = 0; j < int(rsect.sh.NumberOfRelocations); j++ {
			rp = &r[j]
			if Bread(f, symbuf[:10]) != 10 {
				goto bad
			}
			rva := Le32(symbuf[0:])
			symindex := Le32(symbuf[4:])
			type_ := Le16(symbuf[8:])
			if err = readpesym(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:
				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(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 {
				Diag("%s: %s sym == 0!", pn, s.Name)
			}
		} else {
			Diag("%s: %s sectnum < 0!", pn, s.Name)
		}

		if sect == nil {
			return
		}

		if s.Outer != nil {
			if s.Dupok != 0 {
				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.External != 0 && s.Dupok == 0 {
				Diag("%s: duplicate definition of %s", pn, s.Name)
			}
			s.External = 1
		}
	}

	// 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, valuecmp, listsubp)
		}
		if s.Type == obj.STEXT {
			if s.Onlist != 0 {
				log.Fatalf("symbol %s listed multiple times", s.Name)
			}
			s.Onlist = 1
			if Ctxt.Etextp != nil {
				Ctxt.Etextp.Next = s
			} else {
				Ctxt.Textp = s
			}
			Ctxt.Etextp = s
			for s = s.Sub; s != nil; s = s.Sub {
				if s.Onlist != 0 {
					log.Fatalf("symbol %s listed multiple times", s.Name)
				}
				s.Onlist = 1
				Ctxt.Etextp.Next = s
				Ctxt.Etextp = s
			}
		}
	}

	return

bad:
	Diag("%s: malformed pe file: %v", pn, err)
}
예제 #5
0
파일: go.go 프로젝트: rsc/tmp
func deadcode() {
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f deadcode\n", obj.Cputime())
	}

	if Buildmode == BuildmodeShared {
		// Mark all symbols as reachable when building a
		// shared library.
		for s := Ctxt.Allsym; s != nil; s = s.Allsym {
			if s.Type != 0 {
				mark(s)
			}
		}
		mark(Linkrlookup(Ctxt, "main.main", 0))
		mark(Linkrlookup(Ctxt, "main.init", 0))
	} else {
		mark(Linklookup(Ctxt, INITENTRY, 0))
		if Linkshared && Buildmode == BuildmodeExe {
			mark(Linkrlookup(Ctxt, "main.main", 0))
			mark(Linkrlookup(Ctxt, "main.init", 0))
		}
		for i := 0; i < len(markextra); i++ {
			mark(Linklookup(Ctxt, markextra[i], 0))
		}

		for i := 0; i < len(dynexp); i++ {
			mark(dynexp[i])
		}
		markflood()

		// keep each beginning with 'typelink.' if the symbol it points at is being kept.
		for s := Ctxt.Allsym; s != nil; s = s.Allsym {
			if strings.HasPrefix(s.Name, "go.typelink.") {
				s.Reachable = len(s.R) == 1 && s.R[0].Sym.Reachable
			}
		}

		// remove dead text but keep file information (z symbols).
		var last *LSym

		for s := Ctxt.Textp; s != nil; s = s.Next {
			if !s.Reachable {
				continue
			}

			// NOTE: Removing s from old textp and adding to new, shorter textp.
			if last == nil {
				Ctxt.Textp = s
			} else {
				last.Next = s
			}
			last = s
		}

		if last == nil {
			Ctxt.Textp = nil
			Ctxt.Etextp = nil
		} else {
			last.Next = nil
			Ctxt.Etextp = last
		}
	}

	for s := Ctxt.Allsym; s != nil; s = s.Allsym {
		if strings.HasPrefix(s.Name, "go.weak.") {
			s.Special = 1 // do not lay out in data segment
			s.Reachable = true
			s.Hide = 1
		}
	}

	// record field tracking references
	var buf bytes.Buffer
	var p *LSym
	for s := Ctxt.Allsym; s != nil; s = s.Allsym {
		if strings.HasPrefix(s.Name, "go.track.") {
			s.Special = 1 // do not lay out in data segment
			s.Hide = 1
			if s.Reachable {
				buf.WriteString(s.Name[9:])
				for p = s.Reachparent; p != nil; p = p.Reachparent {
					buf.WriteString("\t")
					buf.WriteString(p.Name)
				}
				buf.WriteString("\n")
			}

			s.Type = obj.SCONST
			s.Value = 0
		}
	}

	if tracksym == "" {
		return
	}
	s := Linklookup(Ctxt, tracksym, 0)
	if !s.Reachable {
		return
	}
	addstrdata(tracksym, buf.String())
}
예제 #6
0
파일: data.go 프로젝트: rsc/tmp
func dodata() {
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f dodata\n", obj.Cputime())
	}
	Bflush(&Bso)

	var last *LSym
	datap = nil

	for s := Ctxt.Allsym; s != nil; s = s.Allsym {
		if !s.Reachable || s.Special != 0 {
			continue
		}
		if obj.STEXT < s.Type && s.Type < obj.SXREF {
			if s.Onlist != 0 {
				log.Fatalf("symbol %s listed multiple times", s.Name)
			}
			s.Onlist = 1
			if last == nil {
				datap = s
			} else {
				last.Next = s
			}
			s.Next = nil
			last = s
		}
	}

	for s := datap; s != nil; s = s.Next {
		if int64(len(s.P)) > s.Size {
			Diag("%s: initialize bounds (%d < %d)", s.Name, int64(s.Size), len(s.P))
		}
	}

	/*
	 * now that we have the datap list, but before we start
	 * to assign addresses, record all the necessary
	 * dynamic relocations.  these will grow the relocation
	 * symbol, which is itself data.
	 *
	 * on darwin, we need the symbol table numbers for dynreloc.
	 */
	if HEADTYPE == obj.Hdarwin {
		machosymorder()
	}
	dynreloc()

	/* some symbols may no longer belong in datap (Mach-O) */
	var l **LSym
	var s *LSym
	for l = &datap; ; {
		s = *l
		if s == nil {
			break
		}

		if s.Type <= obj.STEXT || obj.SXREF <= s.Type {
			*l = s.Next
		} else {
			l = &s.Next
		}
	}

	*l = nil

	datap = listsort(datap, datcmp, listnextp)

	/*
	 * allocate sections.  list is sorted by type,
	 * so we can just walk it for each piece we want to emit.
	 * segdata is processed before segtext, because we need
	 * to see all symbols in the .data and .bss sections in order
	 * to generate garbage collection information.
	 */

	/* begin segdata */

	/* skip symbols belonging to segtext */
	s = datap

	for ; s != nil && s.Type < obj.SELFSECT; s = s.Next {
	}

	/* writable ELF sections */
	datsize := int64(0)

	var sect *Section
	for ; s != nil && s.Type < obj.SELFGOT; s = s.Next {
		sect = addsection(&Segdata, s.Name, 06)
		sect.Align = symalign(s)
		datsize = Rnd(datsize, int64(sect.Align))
		sect.Vaddr = uint64(datsize)
		s.Sect = sect
		s.Type = obj.SDATA
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
		sect.Length = uint64(datsize) - sect.Vaddr
	}

	/* .got (and .toc on ppc64) */
	if s.Type == obj.SELFGOT {
		sect := addsection(&Segdata, ".got", 06)
		sect.Align = maxalign(s, obj.SELFGOT)
		datsize = Rnd(datsize, int64(sect.Align))
		sect.Vaddr = uint64(datsize)
		var toc *LSym
		for ; s != nil && s.Type == obj.SELFGOT; s = s.Next {
			datsize = aligndatsize(datsize, s)
			s.Sect = sect
			s.Type = obj.SDATA
			s.Value = int64(uint64(datsize) - sect.Vaddr)

			// Resolve .TOC. symbol for this object file (ppc64)
			toc = Linkrlookup(Ctxt, ".TOC.", int(s.Version))

			if toc != nil {
				toc.Sect = sect
				toc.Outer = s
				toc.Sub = s.Sub
				s.Sub = toc

				toc.Value = 0x8000
			}

			growdatsize(&datsize, s)
		}

		sect.Length = uint64(datsize) - sect.Vaddr
	}

	/* pointer-free data */
	sect = addsection(&Segdata, ".noptrdata", 06)

	sect.Align = maxalign(s, obj.SINITARR-1)
	datsize = Rnd(datsize, int64(sect.Align))
	sect.Vaddr = uint64(datsize)
	Linklookup(Ctxt, "runtime.noptrdata", 0).Sect = sect
	Linklookup(Ctxt, "runtime.enoptrdata", 0).Sect = sect
	for ; s != nil && s.Type < obj.SINITARR; s = s.Next {
		datsize = aligndatsize(datsize, s)
		s.Sect = sect
		s.Type = obj.SDATA
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
	}

	sect.Length = uint64(datsize) - sect.Vaddr

	hasinitarr := Linkshared

	/* shared library initializer */
	switch Buildmode {
	case BuildmodeCArchive, BuildmodeCShared, BuildmodeShared:
		hasinitarr = true
	}

	if hasinitarr {
		sect := addsection(&Segdata, ".init_array", 06)
		sect.Align = maxalign(s, obj.SINITARR)
		datsize = Rnd(datsize, int64(sect.Align))
		sect.Vaddr = uint64(datsize)
		for ; s != nil && s.Type == obj.SINITARR; s = s.Next {
			datsize = aligndatsize(datsize, s)
			s.Sect = sect
			s.Value = int64(uint64(datsize) - sect.Vaddr)
			growdatsize(&datsize, s)
		}

		sect.Length = uint64(datsize) - sect.Vaddr
	}

	/* data */
	sect = addsection(&Segdata, ".data", 06)

	sect.Align = maxalign(s, obj.SBSS-1)
	datsize = Rnd(datsize, int64(sect.Align))
	sect.Vaddr = uint64(datsize)
	Linklookup(Ctxt, "runtime.data", 0).Sect = sect
	Linklookup(Ctxt, "runtime.edata", 0).Sect = sect
	gcdata := Linklookup(Ctxt, "runtime.gcdata", 0)
	var gen ProgGen
	proggeninit(&gen, gcdata)
	for ; s != nil && s.Type < obj.SBSS; s = s.Next {
		if s.Type == obj.SINITARR {
			Ctxt.Cursym = s
			Diag("unexpected symbol type %d", s.Type)
		}

		s.Sect = sect
		s.Type = obj.SDATA
		datsize = aligndatsize(datsize, s)
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		proggenaddsym(&gen, s) // gc
		growdatsize(&datsize, s)
	}

	sect.Length = uint64(datsize) - sect.Vaddr
	proggenfini(&gen, int64(sect.Length)) // gc

	/* bss */
	sect = addsection(&Segdata, ".bss", 06)

	sect.Align = maxalign(s, obj.SNOPTRBSS-1)
	datsize = Rnd(datsize, int64(sect.Align))
	sect.Vaddr = uint64(datsize)
	Linklookup(Ctxt, "runtime.bss", 0).Sect = sect
	Linklookup(Ctxt, "runtime.ebss", 0).Sect = sect
	gcbss := Linklookup(Ctxt, "runtime.gcbss", 0)
	proggeninit(&gen, gcbss)
	for ; s != nil && s.Type < obj.SNOPTRBSS; s = s.Next {
		s.Sect = sect
		datsize = aligndatsize(datsize, s)
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		proggenaddsym(&gen, s) // gc
		growdatsize(&datsize, s)
	}

	sect.Length = uint64(datsize) - sect.Vaddr
	proggenfini(&gen, int64(sect.Length)) // gc

	/* pointer-free bss */
	sect = addsection(&Segdata, ".noptrbss", 06)

	sect.Align = maxalign(s, obj.SNOPTRBSS)
	datsize = Rnd(datsize, int64(sect.Align))
	sect.Vaddr = uint64(datsize)
	Linklookup(Ctxt, "runtime.noptrbss", 0).Sect = sect
	Linklookup(Ctxt, "runtime.enoptrbss", 0).Sect = sect
	for ; s != nil && s.Type == obj.SNOPTRBSS; s = s.Next {
		datsize = aligndatsize(datsize, s)
		s.Sect = sect
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
	}

	sect.Length = uint64(datsize) - sect.Vaddr
	Linklookup(Ctxt, "runtime.end", 0).Sect = sect

	// 6g uses 4-byte relocation offsets, so the entire segment must fit in 32 bits.
	if datsize != int64(uint32(datsize)) {
		Diag("data or bss segment too large")
	}

	if Iself && Linkmode == LinkExternal && s != nil && s.Type == obj.STLSBSS && HEADTYPE != obj.Hopenbsd {
		sect := addsection(&Segdata, ".tbss", 06)
		sect.Align = int32(Thearch.Ptrsize)
		sect.Vaddr = 0
		datsize = 0
		for ; s != nil && s.Type == obj.STLSBSS; s = s.Next {
			datsize = aligndatsize(datsize, s)
			s.Sect = sect
			s.Value = int64(uint64(datsize) - sect.Vaddr)
			growdatsize(&datsize, s)
		}

		sect.Length = uint64(datsize)
	} else {
		// Might be internal linking but still using cgo.
		// In that case, the only possible STLSBSS symbol is runtime.tlsg.
		// Give it offset 0, because it's the only thing here.
		if s != nil && s.Type == obj.STLSBSS && s.Name == "runtime.tlsg" {
			s.Value = 0
			s = s.Next
		}
	}

	if s != nil {
		Ctxt.Cursym = nil
		Diag("unexpected symbol type %d for %s", s.Type, s.Name)
	}

	/*
	 * We finished data, begin read-only data.
	 * Not all systems support a separate read-only non-executable data section.
	 * ELF systems do.
	 * OS X and Plan 9 do not.
	 * Windows PE may, but if so we have not implemented it.
	 * And if we're using external linking mode, the point is moot,
	 * since it's not our decision; that code expects the sections in
	 * segtext.
	 */
	var segro *Segment
	if Iself && Linkmode == LinkInternal {
		segro = &Segrodata
	} else {
		segro = &Segtext
	}

	s = datap

	datsize = 0

	/* read-only executable ELF, Mach-O sections */
	for ; s != nil && s.Type < obj.STYPE; s = s.Next {
		sect = addsection(&Segtext, s.Name, 04)
		sect.Align = symalign(s)
		datsize = Rnd(datsize, int64(sect.Align))
		sect.Vaddr = uint64(datsize)
		s.Sect = sect
		s.Type = obj.SRODATA
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
		sect.Length = uint64(datsize) - sect.Vaddr
	}

	/* read-only data */
	sect = addsection(segro, ".rodata", 04)

	sect.Align = maxalign(s, obj.STYPELINK-1)
	datsize = Rnd(datsize, int64(sect.Align))
	sect.Vaddr = 0
	Linklookup(Ctxt, "runtime.rodata", 0).Sect = sect
	Linklookup(Ctxt, "runtime.erodata", 0).Sect = sect
	for ; s != nil && s.Type < obj.STYPELINK; s = s.Next {
		datsize = aligndatsize(datsize, s)
		s.Sect = sect
		s.Type = obj.SRODATA
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
	}

	sect.Length = uint64(datsize) - sect.Vaddr

	/* typelink */
	sect = addsection(segro, ".typelink", 04)

	sect.Align = maxalign(s, obj.STYPELINK)
	datsize = Rnd(datsize, int64(sect.Align))
	sect.Vaddr = uint64(datsize)
	Linklookup(Ctxt, "runtime.typelink", 0).Sect = sect
	Linklookup(Ctxt, "runtime.etypelink", 0).Sect = sect
	for ; s != nil && s.Type == obj.STYPELINK; s = s.Next {
		datsize = aligndatsize(datsize, s)
		s.Sect = sect
		s.Type = obj.SRODATA
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
	}

	sect.Length = uint64(datsize) - sect.Vaddr

	/* gosymtab */
	sect = addsection(segro, ".gosymtab", 04)

	sect.Align = maxalign(s, obj.SPCLNTAB-1)
	datsize = Rnd(datsize, int64(sect.Align))
	sect.Vaddr = uint64(datsize)
	Linklookup(Ctxt, "runtime.symtab", 0).Sect = sect
	Linklookup(Ctxt, "runtime.esymtab", 0).Sect = sect
	for ; s != nil && s.Type < obj.SPCLNTAB; s = s.Next {
		datsize = aligndatsize(datsize, s)
		s.Sect = sect
		s.Type = obj.SRODATA
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
	}

	sect.Length = uint64(datsize) - sect.Vaddr

	/* gopclntab */
	sect = addsection(segro, ".gopclntab", 04)

	sect.Align = maxalign(s, obj.SELFROSECT-1)
	datsize = Rnd(datsize, int64(sect.Align))
	sect.Vaddr = uint64(datsize)
	Linklookup(Ctxt, "runtime.pclntab", 0).Sect = sect
	Linklookup(Ctxt, "runtime.epclntab", 0).Sect = sect
	for ; s != nil && s.Type < obj.SELFROSECT; s = s.Next {
		datsize = aligndatsize(datsize, s)
		s.Sect = sect
		s.Type = obj.SRODATA
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
	}

	sect.Length = uint64(datsize) - sect.Vaddr

	/* read-only ELF, Mach-O sections */
	for ; s != nil && s.Type < obj.SELFSECT; s = s.Next {
		sect = addsection(segro, s.Name, 04)
		sect.Align = symalign(s)
		datsize = Rnd(datsize, int64(sect.Align))
		sect.Vaddr = uint64(datsize)
		s.Sect = sect
		s.Type = obj.SRODATA
		s.Value = int64(uint64(datsize) - sect.Vaddr)
		growdatsize(&datsize, s)
		sect.Length = uint64(datsize) - sect.Vaddr
	}

	// 6g uses 4-byte relocation offsets, so the entire segment must fit in 32 bits.
	if datsize != int64(uint32(datsize)) {
		Diag("read-only data segment too large")
	}

	/* number the sections */
	n := int32(1)

	for sect := Segtext.Sect; sect != nil; sect = sect.Next {
		sect.Extnum = int16(n)
		n++
	}
	for sect := Segrodata.Sect; sect != nil; sect = sect.Next {
		sect.Extnum = int16(n)
		n++
	}
	for sect := Segdata.Sect; sect != nil; sect = sect.Next {
		sect.Extnum = int16(n)
		n++
	}
}
예제 #7
0
파일: pcln.go 프로젝트: rsc/tmp
func pclntab() {
	funcdata_bytes := int64(0)
	ftab := Linklookup(Ctxt, "runtime.pclntab", 0)
	ftab.Type = obj.SPCLNTAB
	ftab.Reachable = true

	// See golang.org/s/go12symtab for the format. Briefly:
	//	8-byte header
	//	nfunc [thearch.ptrsize bytes]
	//	function table, alternating PC and offset to func struct [each entry thearch.ptrsize bytes]
	//	end PC [thearch.ptrsize bytes]
	//	offset to file table [4 bytes]
	nfunc := int32(0)

	for Ctxt.Cursym = Ctxt.Textp; Ctxt.Cursym != nil; Ctxt.Cursym = Ctxt.Cursym.Next {
		if container(Ctxt.Cursym) == 0 {
			nfunc++
		}
	}

	pclntabNfunc = nfunc
	Symgrow(Ctxt, ftab, 8+int64(Thearch.Ptrsize)+int64(nfunc)*2*int64(Thearch.Ptrsize)+int64(Thearch.Ptrsize)+4)
	setuint32(Ctxt, ftab, 0, 0xfffffffb)
	setuint8(Ctxt, ftab, 6, uint8(Thearch.Minlc))
	setuint8(Ctxt, ftab, 7, uint8(Thearch.Ptrsize))
	setuintxx(Ctxt, ftab, 8, uint64(nfunc), int64(Thearch.Ptrsize))
	pclntabPclntabOffset = int32(8 + Thearch.Ptrsize)

	nfunc = 0
	var last *LSym
	var end int32
	var funcstart int32
	var i int32
	var it Pciter
	var off int32
	var pcln *Pcln
	for Ctxt.Cursym = Ctxt.Textp; Ctxt.Cursym != nil; Ctxt.Cursym = Ctxt.Cursym.Next {
		last = Ctxt.Cursym
		if container(Ctxt.Cursym) != 0 {
			continue
		}
		pcln = Ctxt.Cursym.Pcln
		if pcln == nil {
			pcln = &pclntab_zpcln
		}

		if pclntabFirstFunc == nil {
			pclntabFirstFunc = Ctxt.Cursym
		}

		funcstart = int32(len(ftab.P))
		funcstart += int32(-len(ftab.P)) & (int32(Thearch.Ptrsize) - 1)

		setaddr(Ctxt, ftab, 8+int64(Thearch.Ptrsize)+int64(nfunc)*2*int64(Thearch.Ptrsize), Ctxt.Cursym)
		setuintxx(Ctxt, ftab, 8+int64(Thearch.Ptrsize)+int64(nfunc)*2*int64(Thearch.Ptrsize)+int64(Thearch.Ptrsize), uint64(funcstart), int64(Thearch.Ptrsize))

		// fixed size of struct, checked below
		off = funcstart

		end = funcstart + int32(Thearch.Ptrsize) + 3*4 + 5*4 + int32(pcln.Npcdata)*4 + int32(pcln.Nfuncdata)*int32(Thearch.Ptrsize)
		if pcln.Nfuncdata > 0 && (end&int32(Thearch.Ptrsize-1) != 0) {
			end += 4
		}
		Symgrow(Ctxt, ftab, int64(end))

		// entry uintptr
		off = int32(setaddr(Ctxt, ftab, int64(off), Ctxt.Cursym))

		// name int32
		off = int32(setuint32(Ctxt, ftab, int64(off), uint32(ftabaddstring(ftab, Ctxt.Cursym.Name))))

		// args int32
		// TODO: Move into funcinfo.
		off = int32(setuint32(Ctxt, ftab, int64(off), uint32(Ctxt.Cursym.Args)))

		// frame int32
		// This has been removed (it was never set quite correctly anyway).
		// Nothing should use it.
		// Leave an obviously incorrect value.
		// TODO: Remove entirely.
		off = int32(setuint32(Ctxt, ftab, int64(off), 0x1234567))

		if pcln != &pclntab_zpcln {
			renumberfiles(Ctxt, pcln.File, &pcln.Pcfile)
			if false {
				// Sanity check the new numbering
				for pciterinit(Ctxt, &it, &pcln.Pcfile); it.done == 0; pciternext(&it) {
					if it.value < 1 || it.value > Ctxt.Nhistfile {
						Diag("bad file number in pcfile: %d not in range [1, %d]\n", it.value, Ctxt.Nhistfile)
						errorexit()
					}
				}
			}
		}

		// pcdata
		off = addpctab(ftab, off, &pcln.Pcsp)

		off = addpctab(ftab, off, &pcln.Pcfile)
		off = addpctab(ftab, off, &pcln.Pcline)
		off = int32(setuint32(Ctxt, ftab, int64(off), uint32(pcln.Npcdata)))
		off = int32(setuint32(Ctxt, ftab, int64(off), uint32(pcln.Nfuncdata)))
		for i = 0; i < int32(pcln.Npcdata); i++ {
			off = addpctab(ftab, off, &pcln.Pcdata[i])
		}

		// funcdata, must be pointer-aligned and we're only int32-aligned.
		// Missing funcdata will be 0 (nil pointer).
		if pcln.Nfuncdata > 0 {
			if off&int32(Thearch.Ptrsize-1) != 0 {
				off += 4
			}
			for i = 0; i < int32(pcln.Nfuncdata); i++ {
				if pcln.Funcdata[i] == nil {
					setuintxx(Ctxt, ftab, int64(off)+int64(Thearch.Ptrsize)*int64(i), uint64(pcln.Funcdataoff[i]), int64(Thearch.Ptrsize))
				} else {
					// TODO: Dedup.
					funcdata_bytes += pcln.Funcdata[i].Size

					setaddrplus(Ctxt, ftab, int64(off)+int64(Thearch.Ptrsize)*int64(i), pcln.Funcdata[i], pcln.Funcdataoff[i])
				}
			}

			off += int32(pcln.Nfuncdata) * int32(Thearch.Ptrsize)
		}

		if off != end {
			Diag("bad math in functab: funcstart=%d off=%d but end=%d (npcdata=%d nfuncdata=%d ptrsize=%d)", funcstart, off, end, pcln.Npcdata, pcln.Nfuncdata, Thearch.Ptrsize)
			errorexit()
		}

		nfunc++
	}

	pclntabLastFunc = last
	// Final entry of table is just end pc.
	setaddrplus(Ctxt, ftab, 8+int64(Thearch.Ptrsize)+int64(nfunc)*2*int64(Thearch.Ptrsize), last, last.Size)

	// Start file table.
	start := int32(len(ftab.P))

	start += int32(-len(ftab.P)) & (int32(Thearch.Ptrsize) - 1)
	pclntabFiletabOffset = start
	setuint32(Ctxt, ftab, 8+int64(Thearch.Ptrsize)+int64(nfunc)*2*int64(Thearch.Ptrsize)+int64(Thearch.Ptrsize), uint32(start))

	Symgrow(Ctxt, ftab, int64(start)+(int64(Ctxt.Nhistfile)+1)*4)
	setuint32(Ctxt, ftab, int64(start), uint32(Ctxt.Nhistfile))
	for s := Ctxt.Filesyms; s != nil; s = s.Next {
		setuint32(Ctxt, ftab, int64(start)+s.Value*4, uint32(ftabaddstring(ftab, s.Name)))
	}

	ftab.Size = int64(len(ftab.P))

	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f pclntab=%d bytes, funcdata total %d bytes\n", obj.Cputime(), int64(ftab.Size), int64(funcdata_bytes))
	}
}
예제 #8
0
파일: pobj.go 프로젝트: rsc/tmp
func Ldmain() {
	Ctxt = linknew(Thelinkarch)
	Ctxt.Thechar = int32(Thearch.Thechar)
	Ctxt.Thestring = Thestring
	Ctxt.Diag = Diag
	Ctxt.Bso = &Bso

	Bso = *Binitw(os.Stdout)
	Debug = [128]int{}
	nerrors = 0
	outfile = ""
	HEADTYPE = -1
	INITTEXT = -1
	INITDAT = -1
	INITRND = -1
	INITENTRY = ""
	Linkmode = LinkAuto

	// For testing behavior of go command when tools crash.
	// Undocumented, not in standard flag parser to avoid
	// exposing in usage message.
	for _, arg := range os.Args {
		if arg == "-crash_for_testing" {
			*(*int)(nil) = 0
		}
	}

	if Thearch.Thechar == '5' && Ctxt.Goarm == 5 {
		Debug['F'] = 1
	}

	obj.Flagcount("1", "use alternate profiling code", &Debug['1'])
	if Thearch.Thechar == '6' {
		obj.Flagcount("8", "assume 64-bit addresses", &Debug['8'])
	}
	obj.Flagfn1("B", "info: define ELF NT_GNU_BUILD_ID note", addbuildinfo)
	obj.Flagcount("C", "check Go calls to C code", &Debug['C'])
	obj.Flagint64("D", "addr: data address", &INITDAT)
	obj.Flagstr("E", "sym: entry symbol", &INITENTRY)
	if Thearch.Thechar == '5' {
		obj.Flagcount("G", "debug pseudo-ops", &Debug['G'])
	}
	obj.Flagfn1("I", "interp: set ELF interp", setinterp)
	obj.Flagfn1("L", "dir: add dir to library path", Lflag)
	obj.Flagfn1("H", "head: header type", setheadtype)
	obj.Flagcount("K", "add stack underflow checks", &Debug['K'])
	if Thearch.Thechar == '5' {
		obj.Flagcount("M", "disable software div/mod", &Debug['M'])
	}
	obj.Flagcount("O", "print pc-line tables", &Debug['O'])
	obj.Flagcount("Q", "debug byte-register code gen", &Debug['Q'])
	if Thearch.Thechar == '5' {
		obj.Flagcount("P", "debug code generation", &Debug['P'])
	}
	obj.Flagint32("R", "rnd: address rounding", &INITRND)
	obj.Flagcount("nil", "check type signatures", &Debug['S'])
	obj.Flagint64("T", "addr: text address", &INITTEXT)
	obj.Flagfn0("V", "print version and exit", doversion)
	obj.Flagcount("W", "disassemble input", &Debug['W'])
	obj.Flagfn1("X", "name value: define string data", addstrdata1)
	obj.Flagcount("Z", "clear stack frame on entry", &Debug['Z'])
	obj.Flagcount("a", "disassemble output", &Debug['a'])
	flag.Var(&Buildmode, "buildmode", "build mode to use")
	obj.Flagcount("c", "dump call graph", &Debug['c'])
	obj.Flagcount("d", "disable dynamic executable", &Debug['d'])
	obj.Flagstr("extld", "ld: linker to run in external mode", &extld)
	obj.Flagstr("extldflags", "ldflags: flags for external linker", &extldflags)
	obj.Flagcount("f", "ignore version mismatch", &Debug['f'])
	obj.Flagcount("g", "disable go package data checks", &Debug['g'])
	obj.Flagstr("installsuffix", "suffix: pkg directory suffix", &flag_installsuffix)
	obj.Flagstr("k", "sym: set field tracking symbol", &tracksym)
	obj.Flagfn1("linkmode", "mode: set link mode (internal, external, auto)", setlinkmode)
	flag.BoolVar(&Linkshared, "linkshared", false, "link against installed Go shared libraries")
	obj.Flagcount("n", "dump symbol table", &Debug['n'])
	obj.Flagstr("o", "outfile: set output file", &outfile)
	flag.Var(&rpath, "r", "dir1:dir2:...: set ELF dynamic linker search path")
	obj.Flagcount("race", "enable race detector", &flag_race)
	obj.Flagcount("s", "disable symbol table", &Debug['s'])
	var flagShared int
	if Thearch.Thechar == '5' || Thearch.Thechar == '6' {
		obj.Flagcount("shared", "generate shared object (implies -linkmode external)", &flagShared)
	}
	obj.Flagstr("tmpdir", "dir: leave temporary files in this directory", &tmpdir)
	obj.Flagcount("u", "reject unsafe packages", &Debug['u'])
	obj.Flagcount("v", "print link trace", &Debug['v'])
	obj.Flagcount("w", "disable DWARF generation", &Debug['w'])

	// Clumsy hack to preserve old behavior of -X taking two arguments.
	for i := 0; i < len(os.Args); i++ {
		arg := os.Args[i]
		if (arg == "--X" || arg == "-X") && i+2 < len(os.Args) {
			os.Args[i+2] = "-X=VALUE:" + os.Args[i+2]
			i += 2
		} else if (strings.HasPrefix(arg, "--X=") || strings.HasPrefix(arg, "-X=")) && i+1 < len(os.Args) {
			os.Args[i+1] = "-X=VALUE:" + os.Args[i+1]
			i++
		}
	}
	obj.Flagstr("cpuprofile", "file: write cpu profile to file", &cpuprofile)
	obj.Flagstr("memprofile", "file: write memory profile to file", &memprofile)
	obj.Flagint64("memprofilerate", "set runtime.MemProfileRate", &memprofilerate)
	obj.Flagparse(usage)
	startProfile()
	Ctxt.Bso = &Bso
	Ctxt.Debugvlog = int32(Debug['v'])
	if flagShared != 0 {
		if Buildmode == BuildmodeExe {
			Buildmode = BuildmodeCShared
		} else if Buildmode != BuildmodeCShared {
			Exitf("-shared and -buildmode=%s are incompatible", Buildmode.String())
		}
	}

	if Buildmode != BuildmodeShared && flag.NArg() != 1 {
		usage()
	}

	if outfile == "" {
		if HEADTYPE == obj.Hwindows {
			outfile = fmt.Sprintf("%c.out.exe", Thearch.Thechar)
		} else {
			outfile = fmt.Sprintf("%c.out", Thearch.Thechar)
		}
	}

	libinit() // creates outfile

	if HEADTYPE == -1 {
		HEADTYPE = int32(headtype(goos))
	}
	Ctxt.Headtype = int(HEADTYPE)
	if headstring == "" {
		headstring = Headstr(int(HEADTYPE))
	}

	Thearch.Archinit()

	if Linkshared && !Iself {
		Exitf("-linkshared can only be used on elf systems")
	}

	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "HEADER = -H%d -T0x%x -D0x%x -R0x%x\n", HEADTYPE, uint64(INITTEXT), uint64(INITDAT), uint32(INITRND))
	}
	Bflush(&Bso)

	if Buildmode == BuildmodeShared {
		for i := 0; i < flag.NArg(); i++ {
			arg := flag.Arg(i)
			parts := strings.SplitN(arg, "=", 2)
			var pkgpath, file string
			if len(parts) == 1 {
				pkgpath, file = "main", arg
			} else {
				pkgpath, file = parts[0], parts[1]
			}
			addlibpath(Ctxt, "command line", "command line", file, pkgpath, "")
		}
	} else {
		addlibpath(Ctxt, "command line", "command line", flag.Arg(0), "main", "")
	}
	loadlib()

	if Thearch.Thechar == '5' {
		// mark some functions that are only referenced after linker code editing
		if Debug['F'] != 0 {
			mark(Linkrlookup(Ctxt, "_sfloat", 0))
		}
		mark(Linklookup(Ctxt, "runtime.read_tls_fallback", 0))
	}

	checkgo()
	deadcode()
	callgraph()

	doelf()
	if HEADTYPE == obj.Hdarwin {
		domacho()
	}
	dostkcheck()
	if HEADTYPE == obj.Hwindows {
		dope()
	}
	addexport()
	Thearch.Gentext() // trampolines, call stubs, etc.
	textaddress()
	pclntab()
	findfunctab()
	symtab()
	dodata()
	address()
	doweak()
	reloc()
	Thearch.Asmb()
	undef()
	hostlink()
	archive()
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f cpu time\n", obj.Cputime())
		fmt.Fprintf(&Bso, "%d symbols\n", Ctxt.Nsymbol)
		fmt.Fprintf(&Bso, "%d liveness data\n", liveness)
	}

	Bflush(&Bso)

	errorexit()
}
예제 #9
0
파일: lib.go 프로젝트: rsc/tmp
func objfile(file string, pkg string) {
	pkg = pathtoprefix(pkg)

	if Debug['v'] > 1 {
		fmt.Fprintf(&Bso, "%5.2f ldobj: %s (%s)\n", obj.Cputime(), file, pkg)
	}
	Bflush(&Bso)
	var err error
	var f *Biobuf
	f, err = Bopenr(file)
	if err != nil {
		Exitf("cannot open file %s: %v", file, err)
	}

	magbuf := make([]byte, len(ARMAG))
	if Bread(f, magbuf) != len(magbuf) || !strings.HasPrefix(string(magbuf), ARMAG) {
		/* load it as a regular file */
		l := Bseek(f, 0, 2)

		Bseek(f, 0, 0)
		ldobj(f, pkg, l, file, file, FileObj)
		Bterm(f)

		return
	}

	/* skip over optional __.GOSYMDEF and process __.PKGDEF */
	off := Boffset(f)

	var arhdr ArHdr
	l := nextar(f, off, &arhdr)
	var pname string
	if l <= 0 {
		Diag("%s: short read on archive file symbol header", file)
		goto out
	}

	if strings.HasPrefix(arhdr.name, symname) {
		off += l
		l = nextar(f, off, &arhdr)
		if l <= 0 {
			Diag("%s: short read on archive file symbol header", file)
			goto out
		}
	}

	if !strings.HasPrefix(arhdr.name, pkgname) {
		Diag("%s: cannot find package header", file)
		goto out
	}

	off += l

	if Debug['u'] != 0 {
		ldpkg(f, pkg, atolwhex(arhdr.size), file, Pkgdef)
	}

	/*
	 * load all the object files from the archive now.
	 * this gives us sequential file access and keeps us
	 * from needing to come back later to pick up more
	 * objects.  it breaks the usual C archive model, but
	 * this is Go, not C.  the common case in Go is that
	 * we need to load all the objects, and then we throw away
	 * the individual symbols that are unused.
	 *
	 * loading every object will also make it possible to
	 * load foreign objects not referenced by __.GOSYMDEF.
	 */
	for {
		l = nextar(f, off, &arhdr)
		if l == 0 {
			break
		}
		if l < 0 {
			Exitf("%s: malformed archive", file)
		}

		off += l

		pname = fmt.Sprintf("%s(%s)", file, arhdr.name)
		l = atolwhex(arhdr.size)
		ldobj(f, pkg, l, pname, file, ArchiveObj)
	}

out:
	Bterm(f)
}
예제 #10
0
파일: lib.go 프로젝트: rsc/tmp
func loadlib() {
	switch Buildmode {
	case BuildmodeCShared:
		s := Linklookup(Ctxt, "runtime.islibrary", 0)
		s.Dupok = 1
		Adduint8(Ctxt, s, 1)
	case BuildmodeCArchive:
		s := Linklookup(Ctxt, "runtime.isarchive", 0)
		s.Dupok = 1
		Adduint8(Ctxt, s, 1)
	}

	loadinternal("runtime")
	if Thearch.Thechar == '5' {
		loadinternal("math")
	}
	if flag_race != 0 {
		loadinternal("runtime/race")
	}

	var i int
	for i = 0; i < len(Ctxt.Library); i++ {
		if Debug['v'] > 1 {
			fmt.Fprintf(&Bso, "%5.2f autolib: %s (from %s)\n", obj.Cputime(), Ctxt.Library[i].File, Ctxt.Library[i].Objref)
		}
		iscgo = iscgo || Ctxt.Library[i].Pkg == "runtime/cgo"
		if Ctxt.Library[i].Shlib != "" {
			ldshlibsyms(Ctxt.Library[i].Shlib)
		} else {
			objfile(Ctxt.Library[i].File, Ctxt.Library[i].Pkg)
		}
	}

	if Linkmode == LinkAuto {
		if iscgo && externalobj {
			Linkmode = LinkExternal
		} else {
			Linkmode = LinkInternal
		}

		// Force external linking for android.
		if goos == "android" {
			Linkmode = LinkExternal
		}

		// cgo on Darwin must use external linking
		// we can always use external linking, but then there will be circular
		// dependency problems when compiling natively (external linking requires
		// runtime/cgo, runtime/cgo requires cmd/cgo, but cmd/cgo needs to be
		// compiled using external linking.)
		if (Thearch.Thechar == '5' || Thearch.Thechar == '7') && HEADTYPE == obj.Hdarwin && iscgo {
			Linkmode = LinkExternal
		}
	}

	// cmd/7l doesn't support cgo internal linking
	// This is https://golang.org/issue/10373.
	if iscgo && goarch == "arm64" {
		Linkmode = LinkExternal
	}

	if Linkmode == LinkExternal && !iscgo {
		// This indicates a user requested -linkmode=external.
		// The startup code uses an import of runtime/cgo to decide
		// whether to initialize the TLS.  So give it one.  This could
		// be handled differently but it's an unusual case.
		loadinternal("runtime/cgo")

		if i < len(Ctxt.Library) {
			if Ctxt.Library[i].Shlib != "" {
				ldshlibsyms(Ctxt.Library[i].Shlib)
			} else {
				objfile(Ctxt.Library[i].File, Ctxt.Library[i].Pkg)
			}
		}
	}

	if Linkmode == LinkInternal {
		// Drop all the cgo_import_static declarations.
		// Turns out we won't be needing them.
		for s := Ctxt.Allsym; s != nil; s = s.Allsym {
			if s.Type == obj.SHOSTOBJ {
				// If a symbol was marked both
				// cgo_import_static and cgo_import_dynamic,
				// then we want to make it cgo_import_dynamic
				// now.
				if s.Extname != "" && s.Dynimplib != "" && s.Cgoexport == 0 {
					s.Type = obj.SDYNIMPORT
				} else {
					s.Type = 0
				}
			}
		}
	}

	tlsg := Linklookup(Ctxt, "runtime.tlsg", 0)

	// For most ports, runtime.tlsg is a placeholder symbol for TLS
	// relocation. However, the Android and Darwin arm ports need it
	// to be a real variable.
	//
	// TODO(crawshaw): android should require leaving the tlsg->type
	// alone (as the runtime-provided SNOPTRBSS) just like darwin/arm.
	// But some other part of the linker is expecting STLSBSS.
	if tlsg.Type != obj.SDYNIMPORT && (goos != "darwin" || Thearch.Thechar != '5') {
		tlsg.Type = obj.STLSBSS
	}
	tlsg.Size = int64(Thearch.Ptrsize)
	tlsg.Reachable = true
	Ctxt.Tlsg = tlsg

	// Now that we know the link mode, trim the dynexp list.
	x := CgoExportDynamic

	if Linkmode == LinkExternal {
		x = CgoExportStatic
	}
	w := 0
	for i := 0; i < len(dynexp); i++ {
		if int(dynexp[i].Cgoexport)&x != 0 {
			dynexp[w] = dynexp[i]
			w++
		}
	}
	dynexp = dynexp[:w]

	// In internal link mode, read the host object files.
	if Linkmode == LinkInternal {
		hostobjs()
	} else {
		hostlinksetup()
	}

	// We've loaded all the code now.
	// If there are no dynamic libraries needed, gcc disables dynamic linking.
	// Because of this, glibc's dynamic ELF loader occasionally (like in version 2.13)
	// assumes that a dynamic binary always refers to at least one dynamic library.
	// Rather than be a source of test cases for glibc, disable dynamic linking
	// the same way that gcc would.
	//
	// Exception: on OS X, programs such as Shark only work with dynamic
	// binaries, so leave it enabled on OS X (Mach-O) binaries.
	// Also leave it enabled on Solaris which doesn't support
	// statically linked binaries.
	if Buildmode == BuildmodeExe && havedynamic == 0 && HEADTYPE != obj.Hdarwin && HEADTYPE != obj.Hsolaris {
		Debug['d'] = 1
	}

	importcycles()
}
예제 #11
0
파일: lib.go 프로젝트: rsc/tmp
func genasmsym(put func(*LSym, string, int, int64, int64, int, *LSym)) {
	// These symbols won't show up in the first loop below because we
	// skip STEXT symbols. Normal STEXT symbols are emitted by walking textp.
	s := Linklookup(Ctxt, "runtime.text", 0)

	if s.Type == obj.STEXT {
		put(s, s.Name, 'T', s.Value, s.Size, int(s.Version), nil)
	}
	s = Linklookup(Ctxt, "runtime.etext", 0)
	if s.Type == obj.STEXT {
		put(s, s.Name, 'T', s.Value, s.Size, int(s.Version), nil)
	}

	for s := Ctxt.Allsym; s != nil; s = s.Allsym {
		if s.Hide != 0 || (s.Name[0] == '.' && s.Version == 0 && s.Name != ".rathole") {
			continue
		}
		switch s.Type & obj.SMASK {
		case obj.SCONST,
			obj.SRODATA,
			obj.SSYMTAB,
			obj.SPCLNTAB,
			obj.SINITARR,
			obj.SDATA,
			obj.SNOPTRDATA,
			obj.SELFROSECT,
			obj.SMACHOGOT,
			obj.STYPE,
			obj.SSTRING,
			obj.SGOSTRING,
			obj.SGOFUNC,
			obj.SWINDOWS:
			if !s.Reachable {
				continue
			}
			put(s, s.Name, 'D', Symaddr(s), s.Size, int(s.Version), s.Gotype)

		case obj.SBSS, obj.SNOPTRBSS:
			if !s.Reachable {
				continue
			}
			if len(s.P) > 0 {
				Diag("%s should not be bss (size=%d type=%d special=%d)", s.Name, int(len(s.P)), s.Type, s.Special)
			}
			put(s, s.Name, 'B', Symaddr(s), s.Size, int(s.Version), s.Gotype)

		case obj.SFILE:
			put(nil, s.Name, 'f', s.Value, 0, int(s.Version), nil)

		case obj.SHOSTOBJ:
			if HEADTYPE == obj.Hwindows || Iself {
				put(s, s.Name, 'U', s.Value, 0, int(s.Version), nil)
			}

		case obj.SDYNIMPORT:
			if !s.Reachable {
				continue
			}
			put(s, s.Extname, 'U', 0, 0, int(s.Version), nil)

		case obj.STLSBSS:
			if Linkmode == LinkExternal && HEADTYPE != obj.Hopenbsd {
				var type_ int
				if goos == "android" {
					type_ = 'B'
				} else {
					type_ = 't'
				}
				put(s, s.Name, type_, Symaddr(s), s.Size, int(s.Version), s.Gotype)
			}
		}
	}

	var a *Auto
	var off int32
	for s := Ctxt.Textp; s != nil; s = s.Next {
		put(s, s.Name, 'T', s.Value, s.Size, int(s.Version), s.Gotype)

		// NOTE(ality): acid can't produce a stack trace without .frame symbols
		put(nil, ".frame", 'm', int64(s.Locals)+int64(Thearch.Ptrsize), 0, 0, nil)

		for a = s.Autom; a != nil; a = a.Link {
			// Emit a or p according to actual offset, even if label is wrong.
			// This avoids negative offsets, which cannot be encoded.
			if a.Name != obj.A_AUTO && a.Name != obj.A_PARAM {
				continue
			}

			// compute offset relative to FP
			if a.Name == obj.A_PARAM {
				off = a.Aoffset
			} else {
				off = a.Aoffset - int32(Thearch.Ptrsize)
			}

			// FP
			if off >= 0 {
				put(nil, a.Asym.Name, 'p', int64(off), 0, 0, a.Gotype)
				continue
			}

			// SP
			if off <= int32(-Thearch.Ptrsize) {
				put(nil, a.Asym.Name, 'a', -(int64(off) + int64(Thearch.Ptrsize)), 0, 0, a.Gotype)
				continue
			}
		}
	}

	// Otherwise, off is addressing the saved program counter.
	// Something underhanded is going on. Say nothing.
	if Debug['v'] != 0 || Debug['n'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f symsize = %d\n", obj.Cputime(), uint32(Symsize))
	}
	Bflush(&Bso)
}
예제 #12
0
파일: lib.go 프로젝트: rsc/tmp
func ldshlibsyms(shlib string) {
	found := false
	libpath := ""
	for _, libdir := range Ctxt.Libdir {
		libpath = filepath.Join(libdir, shlib)
		if _, err := os.Stat(libpath); err == nil {
			found = true
			break
		}
	}
	if !found {
		Diag("cannot find shared library: %s", shlib)
		return
	}
	for _, processedname := range Ctxt.Shlibs {
		if processedname == libpath {
			return
		}
	}
	if Ctxt.Debugvlog > 1 && Ctxt.Bso != nil {
		fmt.Fprintf(Ctxt.Bso, "%5.2f ldshlibsyms: found library with name %s at %s\n", obj.Cputime(), shlib, libpath)
		Bflush(Ctxt.Bso)
	}

	f, err := elf.Open(libpath)
	if err != nil {
		Diag("cannot open shared library: %s", libpath)
		return
	}
	defer f.Close()
	syms, err := f.Symbols()
	if err != nil {
		Diag("cannot read symbols from shared library: %s", libpath)
		return
	}
	// If a package has a global variable of a type defined in another shared
	// library, we need to know the gcmask used by the type, if any.  To support
	// this, we read all the runtime.gcbits.* symbols, keep a map of address to
	// gcmask, and after we're read all the symbols, read the addresses of the
	// gcmasks symbols out of the type data to look up the gcmask for each type.
	// This depends on the fact that the runtime.gcbits.* symbols are local (so
	// the address is actually present in the type data and we don't have to
	// search all relocations to find the ones which correspond to gcmasks) and
	// also that the shared library we are linking against has not had the symbol
	// table removed.
	gcmasks := make(map[uint64][]byte)
	types := []*LSym{}
	for _, s := range syms {
		if elf.ST_TYPE(s.Info) == elf.STT_NOTYPE || elf.ST_TYPE(s.Info) == elf.STT_SECTION {
			continue
		}
		if s.Section == elf.SHN_UNDEF {
			continue
		}
		if strings.HasPrefix(s.Name, "_") {
			continue
		}
		if strings.HasPrefix(s.Name, "runtime.gcbits.0x") {
			data := make([]byte, s.Size)
			sect := f.Sections[s.Section]
			if sect.Type == elf.SHT_PROGBITS {
				n, err := sect.ReadAt(data, int64(s.Value-sect.Offset))
				if uint64(n) != s.Size {
					Diag("Error reading contents of %s: %v", s.Name, err)
				}
			}
			gcmasks[s.Value] = data
		}
		if elf.ST_BIND(s.Info) != elf.STB_GLOBAL {
			continue
		}
		lsym := Linklookup(Ctxt, s.Name, 0)
		if lsym.Type != 0 && lsym.Dupok == 0 {
			Diag(
				"Found duplicate symbol %s reading from %s, first found in %s",
				s.Name, shlib, lsym.File)
		}
		lsym.Type = obj.SDYNIMPORT
		lsym.File = libpath
		if strings.HasPrefix(lsym.Name, "type.") {
			data := make([]byte, s.Size)
			sect := f.Sections[s.Section]
			if sect.Type == elf.SHT_PROGBITS {
				n, err := sect.ReadAt(data, int64(s.Value-sect.Offset))
				if uint64(n) != s.Size {
					Diag("Error reading contents of %s: %v", s.Name, err)
				}
				lsym.P = data
			}
			if !strings.HasPrefix(lsym.Name, "type..") {
				types = append(types, lsym)
			}
		}
	}

	for _, t := range types {
		if decodetype_noptr(t) != 0 || decodetype_usegcprog(t) != 0 {
			continue
		}
		// The expression on the next line is a copy of the expression from
		// decodetype_gcmask in decodesym.go, which in turn depends on details of
		// how the type data is laid out, as seen in gc/reflect.go:dcommontype.
		addr := decode_inuxi(t.P[1*int32(Thearch.Ptrsize)+8+1*int32(Thearch.Ptrsize):], Thearch.Ptrsize)
		tgcmask, ok := gcmasks[addr]
		if !ok {
			Diag("bits not found for %s at %d", t.Name, addr)
		}
		t.gcmask = tgcmask
	}

	// We might have overwritten some functions above (this tends to happen for the
	// autogenerated type equality/hashing functions) and we don't want to generated
	// pcln table entries for these any more so unstitch them from the Textp linked
	// list.
	var last *LSym

	for s := Ctxt.Textp; s != nil; s = s.Next {
		if s.Type == obj.SDYNIMPORT {
			continue
		}

		if last == nil {
			Ctxt.Textp = s
		} else {
			last.Next = s
		}
		last = s
	}

	if last == nil {
		Ctxt.Textp = nil
		Ctxt.Etextp = nil
	} else {
		last.Next = nil
		Ctxt.Etextp = last
	}

	Ctxt.Shlibs = append(Ctxt.Shlibs, libpath)
}
예제 #13
0
파일: ldelf.go 프로젝트: rsc/tmp
func ldelf(f *Biobuf, pkg string, length int64, pn string) {
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f ldelf %s\n", obj.Cputime(), pn)
	}

	Ctxt.Version++
	base := int32(Boffset(f))

	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 *LSym
	var sect *ElfSect
	var sym ElfSym
	var symbols []*LSym
	if Bread(f, hdrbuf[:]) != len(hdrbuf) {
		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 = int64(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 {
		Diag("%s: elf but not elf relocatable object", pn)
		return
	}

	switch Thearch.Thechar {
	default:
		Diag("%s: elf %s unimplemented", pn, Thestring)
		return

	case '5':
		if e != binary.LittleEndian || elfobj.machine != ElfMachArm || hdr.Ident[4] != ElfClass32 {
			Diag("%s: elf object but not arm", pn)
			return
		}

	case '6':
		if e != binary.LittleEndian || elfobj.machine != ElfMachAmd64 || hdr.Ident[4] != ElfClass64 {
			Diag("%s: elf object but not amd64", pn)
			return
		}

	case '7':
		if e != binary.LittleEndian || elfobj.machine != ElfMachArm64 || hdr.Ident[4] != ElfClass64 {
			Diag("%s: elf object but not arm64", pn)
			return
		}

	case '8':
		if e != binary.LittleEndian || elfobj.machine != ElfMach386 || hdr.Ident[4] != ElfClass32 {
			Diag("%s: elf object but not 386", pn)
			return
		}

	case '9':
		if elfobj.machine != ElfMachPower64 || hdr.Ident[4] != ElfClass64 {
			Diag("%s: elf object but not ppc64", 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 Bseek(f, 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 = uint32(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 = uint32(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) {
		Diag("%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_ != 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 = Linklookup(Ctxt, name, Ctxt.Version)

		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([]*LSym, elfobj.nsymtab)

	for i := 1; i < elfobj.nsymtab; i++ {
		if err = readelfsym(elfobj, i, &sym, 1); 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:][0]
		if sect.sym == nil {
			if strings.HasPrefix(sym.name, ".Linfo_string") { // clang does this
				continue
			}
			Diag("%s: sym#%d: ignoring %s in section %d (type %d)", pn, i, sym.name, sym.shndx, sym.type_)
			continue
		}

		s = sym.sym
		if s.Outer != nil {
			if s.Dupok != 0 {
				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.Cgoexport&CgoExportDynamic == 0 {
			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.External != 0 && s.Dupok == 0 {
				Diag("%s: duplicate definition of %s", pn, s.Name)
			}
			s.External = 1
		}

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

	// 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, valuecmp, listsubp)
		}
		if s.Type == obj.STEXT {
			if s.Onlist != 0 {
				log.Fatalf("symbol %s listed multiple times", s.Name)
			}
			s.Onlist = 1
			if Ctxt.Etextp != nil {
				Ctxt.Etextp.Next = s
			} else {
				Ctxt.Textp = s
			}
			Ctxt.Etextp = s
			for s = s.Sub; s != nil; s = s.Sub {
				if s.Onlist != 0 {
					log.Fatalf("symbol %s listed multiple times", s.Name)
				}
				s.Onlist = 1
				Ctxt.Etextp.Next = s
				Ctxt.Etextp = 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(elfobj, int(info>>32), &sym, 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 = int32(reltype(pn, int(uint32(info)), &rp.Siz))
			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 {
					Diag("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:
	Diag("%s: malformed elf file: %v", pn, err)
}