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go/src/cmd/link/internal/ld/lib.go
Cherry Zhang 516c29a79f [dev.link] cmd/link: pass reloc by value to Adddynrel2 
Adddynrel2 is a function pointer. In dynrelocsym we pass &r to
it, which will cause r to escape. Pass it by value instead.

Linking cmd/compile,

name           old alloc/op   new alloc/op   delta
Dodata_GC        15.8MB ± 0%     5.9MB ± 0%  -62.55%  (p=0.008 n=5+5)

Change-Id: Ib86005d1026ebaca57777b27ead037e613585f44
Reviewed-on: https://go-review.googlesource.com/c/go/+/231045
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
2020-04-30 15:53:43 +00:00

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// Inferno utils/8l/asm.c
// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/8l/asm.c
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package ld
import (
"bytes"
"cmd/internal/bio"
"cmd/internal/goobj2"
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"cmd/link/internal/loadelf"
"cmd/link/internal/loader"
"cmd/link/internal/loadmacho"
"cmd/link/internal/loadpe"
"cmd/link/internal/loadxcoff"
"cmd/link/internal/sym"
"crypto/sha1"
"debug/elf"
"debug/macho"
"encoding/base64"
"encoding/binary"
"encoding/hex"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"os/exec"
"path/filepath"
"runtime"
"sort"
"strings"
"sync"
)
// Data layout and relocation.
// Derived from Inferno utils/6l/l.h
// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/l.h
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
type LookupFn func(name string, version int) *sym.Symbol
// ArchSyms holds a number of architecture specific symbols used during
// relocation. Rather than allowing them universal access to all symbols,
// we keep a subset for relocation application.
type ArchSyms struct {
TOC *sym.Symbol
DotTOC []*sym.Symbol // for each version
GOT *sym.Symbol
PLT *sym.Symbol
GOTPLT *sym.Symbol
Tlsg *sym.Symbol
Tlsoffset int
Dynamic *sym.Symbol
DynSym *sym.Symbol
DynStr *sym.Symbol
// Elf specific
Rel *sym.Symbol
Rela *sym.Symbol
RelPLT *sym.Symbol
RelaPLT *sym.Symbol
// Darwin symbols
LinkEditGOT *sym.Symbol
LinkEditPLT *sym.Symbol
// ----- loader.Sym equivalents -----
Rel2 loader.Sym
Rela2 loader.Sym
RelPLT2 loader.Sym
RelaPLT2 loader.Sym
LinkEditGOT2 loader.Sym
LinkEditPLT2 loader.Sym
TOC2 loader.Sym
DotTOC2 []loader.Sym // for each version
GOT2 loader.Sym
PLT2 loader.Sym
GOTPLT2 loader.Sym
Tlsg2 loader.Sym
Dynamic2 loader.Sym
DynSym2 loader.Sym
DynStr2 loader.Sym
}
const BeforeLoadlibFull = 1
const AfterLoadlibFull = 2
// mkArchSym is a helper for setArchSyms, invoked once before loadlibfull
// and once after. On the first call it creates a loader.Sym with the
// specified name, and on the second call a corresponding sym.Symbol.
func (ctxt *Link) mkArchSym(which int, name string, ver int, ls *loader.Sym, ss **sym.Symbol) {
if which == BeforeLoadlibFull {
*ls = ctxt.loader.LookupOrCreateSym(name, ver)
} else {
*ss = ctxt.loader.Syms[*ls]
}
}
// mkArchVecSym is similar to setArchSyms, but operates on elements within
// a slice, where each element corresponds to some symbol version.
func (ctxt *Link) mkArchSymVec(which int, name string, ver int, ls []loader.Sym, ss []*sym.Symbol) {
if which == BeforeLoadlibFull {
ls[ver] = ctxt.loader.LookupOrCreateSym(name, ver)
} else if ls[ver] != 0 {
ss[ver] = ctxt.loader.Syms[ls[ver]]
}
}
// setArchSyms sets up the ArchSyms structure, and must be called before
// relocations are applied. This function is invoked twice, once prior
// to loadlibfull(), and once after the work of loadlibfull is complete.
func (ctxt *Link) setArchSyms(which int) {
if which != BeforeLoadlibFull && which != AfterLoadlibFull {
panic("internal error")
}
ctxt.mkArchSym(which, ".got", 0, &ctxt.GOT2, &ctxt.GOT)
ctxt.mkArchSym(which, ".plt", 0, &ctxt.PLT2, &ctxt.PLT)
ctxt.mkArchSym(which, ".got.plt", 0, &ctxt.GOTPLT2, &ctxt.GOTPLT)
ctxt.mkArchSym(which, ".dynamic", 0, &ctxt.Dynamic2, &ctxt.Dynamic)
ctxt.mkArchSym(which, ".dynsym", 0, &ctxt.DynSym2, &ctxt.DynSym)
ctxt.mkArchSym(which, ".dynstr", 0, &ctxt.DynStr2, &ctxt.DynStr)
if ctxt.IsPPC64() {
ctxt.mkArchSym(which, "TOC", 0, &ctxt.TOC2, &ctxt.TOC)
// NB: note the +2 below for DotTOC2 compared to the +1 for
// DocTOC. This is because loadlibfull() creates an additional
// syms version during conversion of loader.Sym symbols to
// *sym.Symbol symbols. Symbols that are assigned this final
// version are not going to have TOC references, so it should
// be ok for them to inherit an invalid .TOC. symbol.
if which == BeforeLoadlibFull {
ctxt.DotTOC2 = make([]loader.Sym, ctxt.Syms.MaxVersion()+2)
} else {
ctxt.DotTOC = make([]*sym.Symbol, ctxt.Syms.MaxVersion()+1)
}
for i := 0; i <= ctxt.Syms.MaxVersion(); i++ {
if i >= 2 && i < sym.SymVerStatic { // these versions are not used currently
continue
}
ctxt.mkArchSymVec(which, ".TOC.", i, ctxt.DotTOC2, ctxt.DotTOC)
}
}
if ctxt.IsElf() {
ctxt.mkArchSym(which, ".rel", 0, &ctxt.Rel2, &ctxt.Rel)
ctxt.mkArchSym(which, ".rela", 0, &ctxt.Rela2, &ctxt.Rela)
ctxt.mkArchSym(which, ".rel.plt", 0, &ctxt.RelPLT2, &ctxt.RelPLT)
ctxt.mkArchSym(which, ".rela.plt", 0, &ctxt.RelaPLT2, &ctxt.RelaPLT)
}
if ctxt.IsDarwin() {
ctxt.mkArchSym(which, ".linkedit.got", 0, &ctxt.LinkEditGOT2, &ctxt.LinkEditGOT)
ctxt.mkArchSym(which, ".linkedit.plt", 0, &ctxt.LinkEditPLT2, &ctxt.LinkEditPLT)
}
}
type Arch struct {
Funcalign int
Maxalign int
Minalign int
Dwarfregsp int
Dwarfreglr int
Androiddynld string
Linuxdynld string
Freebsddynld string
Netbsddynld string
Openbsddynld string
Dragonflydynld string
Solarisdynld string
Adddynrel func(*Target, *loader.Loader, *ArchSyms, *sym.Symbol, *sym.Reloc) bool
Adddynrel2 func(*Target, *loader.Loader, *ArchSyms, loader.Sym, loader.Reloc2, int) bool
Archinit func(*Link)
// Archreloc is an arch-specific hook that assists in relocation processing
// (invoked by 'relocsym'); it handles target-specific relocation tasks.
// Here "rel" is the current relocation being examined, "sym" is the symbol
// containing the chunk of data to which the relocation applies, and "off"
// is the contents of the to-be-relocated data item (from sym.P). Return
// value is the appropriately relocated value (to be written back to the
// same spot in sym.P), a boolean indicating if the external relocations'
// been used, and a boolean indicating success/failure (a failing value
// indicates a fatal error).
Archreloc func(target *Target, syms *ArchSyms, rel *sym.Reloc, sym *sym.Symbol,
offset int64) (relocatedOffset int64, success bool)
Archreloc2 func(*Target, *loader.Loader, *ArchSyms, loader.Reloc2, *loader.ExtReloc, loader.Sym, int64) (int64, bool, bool)
// Archrelocvariant is a second arch-specific hook used for
// relocation processing; it handles relocations where r.Type is
// insufficient to describe the relocation (r.Variant !=
// sym.RV_NONE). Here "rel" is the relocation being applied, "sym"
// is the symbol containing the chunk of data to which the
// relocation applies, and "off" is the contents of the
// to-be-relocated data item (from sym.P). Return is an updated
// offset value.
Archrelocvariant func(target *Target, syms *ArchSyms, rel *sym.Reloc, sym *sym.Symbol,
offset int64) (relocatedOffset int64)
// Generate a trampoline for a call from s to rs if necessary. ri is
// index of the relocation.
Trampoline func(ctxt *Link, ldr *loader.Loader, ri int, rs, s loader.Sym)
// Asmb and Asmb2 are arch-specific routines that write the output
// file. Typically, Asmb writes most of the content (sections and
// segments), for which we have computed the size and offset. Asmb2
// writes the rest.
Asmb func(*Link, *loader.Loader)
Asmb2 func(*Link)
Elfreloc1 func(*Link, *sym.Reloc, int64) bool
Elfsetupplt func(ctxt *Link, plt, gotplt *loader.SymbolBuilder, dynamic loader.Sym)
Gentext func(*Link)
Gentext2 func(*Link, *loader.Loader)
Machoreloc1 func(*sys.Arch, *OutBuf, *sym.Symbol, *sym.Reloc, int64) bool
PEreloc1 func(*sys.Arch, *OutBuf, *sym.Symbol, *sym.Reloc, int64) bool
Xcoffreloc1 func(*sys.Arch, *OutBuf, *sym.Symbol, *sym.Reloc, int64) bool
// TLSIEtoLE converts a TLS Initial Executable relocation to
// a TLS Local Executable relocation.
//
// This is possible when a TLS IE relocation refers to a local
// symbol in an executable, which is typical when internally
// linking PIE binaries.
TLSIEtoLE func(P []byte, off, size int)
// optional override for assignAddress
AssignAddress func(ldr *loader.Loader, sect *sym.Section, n int, s loader.Sym, va uint64, isTramp bool) (*sym.Section, int, uint64)
}
var (
thearch Arch
Lcsize int32
rpath Rpath
Spsize int32
Symsize int32
)
const (
MINFUNC = 16 // minimum size for a function
)
// DynlinkingGo reports whether we are producing Go code that can live
// in separate shared libraries linked together at runtime.
func (ctxt *Link) DynlinkingGo() bool {
if !ctxt.Loaded {
panic("DynlinkingGo called before all symbols loaded")
}
return ctxt.BuildMode == BuildModeShared || ctxt.linkShared || ctxt.BuildMode == BuildModePlugin || ctxt.canUsePlugins
}
// CanUsePlugins reports whether a plugins can be used
func (ctxt *Link) CanUsePlugins() bool {
if !ctxt.Loaded {
panic("CanUsePlugins called before all symbols loaded")
}
return ctxt.canUsePlugins
}
var (
dynexp []*sym.Symbol
dynlib []string
ldflag []string
havedynamic int
Funcalign int
iscgo bool
elfglobalsymndx int
interpreter string
debug_s bool // backup old value of debug['s']
HEADR int32
nerrors int
liveness int64
// See -strictdups command line flag.
checkStrictDups int // 0=off 1=warning 2=error
strictDupMsgCount int
)
var (
Segtext sym.Segment
Segrodata sym.Segment
Segrelrodata sym.Segment
Segdata sym.Segment
Segdwarf sym.Segment
)
const pkgdef = "__.PKGDEF"
var (
// Set if we see an object compiled by the host compiler that is not
// from a package that is known to support internal linking mode.
externalobj = false
theline string
)
func Lflag(ctxt *Link, arg string) {
ctxt.Libdir = append(ctxt.Libdir, arg)
}
/*
* Unix doesn't like it when we write to a running (or, sometimes,
* recently run) binary, so remove the output file before writing it.
* On Windows 7, remove() can force a subsequent create() to fail.
* S_ISREG() does not exist on Plan 9.
*/
func mayberemoveoutfile() {
if fi, err := os.Lstat(*flagOutfile); err == nil && !fi.Mode().IsRegular() {
return
}
os.Remove(*flagOutfile)
}
func libinit(ctxt *Link) {
Funcalign = thearch.Funcalign
// add goroot to the end of the libdir list.
suffix := ""
suffixsep := ""
if *flagInstallSuffix != "" {
suffixsep = "_"
suffix = *flagInstallSuffix
} else if *flagRace {
suffixsep = "_"
suffix = "race"
} else if *flagMsan {
suffixsep = "_"
suffix = "msan"
}
Lflag(ctxt, filepath.Join(objabi.GOROOT, "pkg", fmt.Sprintf("%s_%s%s%s", objabi.GOOS, objabi.GOARCH, suffixsep, suffix)))
mayberemoveoutfile()
if err := ctxt.Out.Open(*flagOutfile); err != nil {
Exitf("cannot create %s: %v", *flagOutfile, err)
}
if *flagEntrySymbol == "" {
switch ctxt.BuildMode {
case BuildModeCShared, BuildModeCArchive:
*flagEntrySymbol = fmt.Sprintf("_rt0_%s_%s_lib", objabi.GOARCH, objabi.GOOS)
case BuildModeExe, BuildModePIE:
*flagEntrySymbol = fmt.Sprintf("_rt0_%s_%s", objabi.GOARCH, objabi.GOOS)
case BuildModeShared, BuildModePlugin:
// No *flagEntrySymbol for -buildmode=shared and plugin
default:
Errorf(nil, "unknown *flagEntrySymbol for buildmode %v", ctxt.BuildMode)
}
}
}
func exitIfErrors() {
if nerrors != 0 || checkStrictDups > 1 && strictDupMsgCount > 0 {
mayberemoveoutfile()
Exit(2)
}
}
func errorexit() {
exitIfErrors()
Exit(0)
}
func loadinternal(ctxt *Link, name string) *sym.Library {
zerofp := goobj2.FingerprintType{}
if ctxt.linkShared && ctxt.PackageShlib != nil {
if shlib := ctxt.PackageShlib[name]; shlib != "" {
return addlibpath(ctxt, "internal", "internal", "", name, shlib, zerofp)
}
}
if ctxt.PackageFile != nil {
if pname := ctxt.PackageFile[name]; pname != "" {
return addlibpath(ctxt, "internal", "internal", pname, name, "", zerofp)
}
ctxt.Logf("loadinternal: cannot find %s\n", name)
return nil
}
for _, libdir := range ctxt.Libdir {
if ctxt.linkShared {
shlibname := filepath.Join(libdir, name+".shlibname")
if ctxt.Debugvlog != 0 {
ctxt.Logf("searching for %s.a in %s\n", name, shlibname)
}
if _, err := os.Stat(shlibname); err == nil {
return addlibpath(ctxt, "internal", "internal", "", name, shlibname, zerofp)
}
}
pname := filepath.Join(libdir, name+".a")
if ctxt.Debugvlog != 0 {
ctxt.Logf("searching for %s.a in %s\n", name, pname)
}
if _, err := os.Stat(pname); err == nil {
return addlibpath(ctxt, "internal", "internal", pname, name, "", zerofp)
}
}
ctxt.Logf("warning: unable to find %s.a\n", name)
return nil
}
// extld returns the current external linker.
func (ctxt *Link) extld() string {
if *flagExtld == "" {
*flagExtld = "gcc"
}
return *flagExtld
}
// findLibPathCmd uses cmd command to find gcc library libname.
// It returns library full path if found, or "none" if not found.
func (ctxt *Link) findLibPathCmd(cmd, libname string) string {
extld := ctxt.extld()
args := hostlinkArchArgs(ctxt.Arch)
args = append(args, cmd)
if ctxt.Debugvlog != 0 {
ctxt.Logf("%s %v\n", extld, args)
}
out, err := exec.Command(extld, args...).Output()
if err != nil {
if ctxt.Debugvlog != 0 {
ctxt.Logf("not using a %s file because compiler failed\n%v\n%s\n", libname, err, out)
}
return "none"
}
return strings.TrimSpace(string(out))
}
// findLibPath searches for library libname.
// It returns library full path if found, or "none" if not found.
func (ctxt *Link) findLibPath(libname string) string {
return ctxt.findLibPathCmd("--print-file-name="+libname, libname)
}
func (ctxt *Link) loadlib() {
var flags uint32
switch *FlagStrictDups {
case 0:
// nothing to do
case 1, 2:
flags = loader.FlagStrictDups
default:
log.Fatalf("invalid -strictdups flag value %d", *FlagStrictDups)
}
ctxt.loader = loader.NewLoader(flags, elfsetstring, &ctxt.ErrorReporter.ErrorReporter)
ctxt.ErrorReporter.SymName = func(s loader.Sym) string {
return ctxt.loader.SymName(s)
}
ctxt.cgo_export_static = make(map[string]bool)
ctxt.cgo_export_dynamic = make(map[string]bool)
// ctxt.Library grows during the loop, so not a range loop.
i := 0
for ; i < len(ctxt.Library); i++ {
lib := ctxt.Library[i]
if lib.Shlib == "" {
if ctxt.Debugvlog > 1 {
ctxt.Logf("autolib: %s (from %s)\n", lib.File, lib.Objref)
}
loadobjfile(ctxt, lib)
}
}
// load internal packages, if not already
if *flagRace {
loadinternal(ctxt, "runtime/race")
}
if *flagMsan {
loadinternal(ctxt, "runtime/msan")
}
loadinternal(ctxt, "runtime")
for ; i < len(ctxt.Library); i++ {
lib := ctxt.Library[i]
if lib.Shlib == "" {
loadobjfile(ctxt, lib)
}
}
// At this point, the Go objects are "preloaded". Not all the symbols are
// added to the symbol table (only defined package symbols are). Looking
// up symbol by name may not get expected result.
iscgo = ctxt.LibraryByPkg["runtime/cgo"] != nil
ctxt.canUsePlugins = ctxt.LibraryByPkg["plugin"] != nil
// We now have enough information to determine the link mode.
determineLinkMode(ctxt)
if ctxt.LinkMode == LinkExternal && !iscgo && !(objabi.GOOS == "darwin" && ctxt.BuildMode != BuildModePlugin && ctxt.Arch.Family == sys.AMD64) {
// 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.
if lib := loadinternal(ctxt, "runtime/cgo"); lib != nil && lib.Shlib == "" {
if ctxt.BuildMode == BuildModeShared || ctxt.linkShared {
Exitf("cannot implicitly include runtime/cgo in a shared library")
}
loadobjfile(ctxt, lib)
}
}
// Add non-package symbols and references of externally defined symbols.
ctxt.loader.LoadNonpkgSyms(ctxt.Arch)
// Load symbols from shared libraries, after all Go object symbols are loaded.
for _, lib := range ctxt.Library {
if lib.Shlib != "" {
if ctxt.Debugvlog > 1 {
ctxt.Logf("autolib: %s (from %s)\n", lib.Shlib, lib.Objref)
}
ldshlibsyms(ctxt, lib.Shlib)
}
}
// Process cgo directives (has to be done before host object loading).
ctxt.loadcgodirectives()
// Conditionally load host objects, or setup for external linking.
hostobjs(ctxt)
hostlinksetup(ctxt)
if ctxt.LinkMode == LinkInternal && len(hostobj) != 0 {
// If we have any undefined symbols in external
// objects, try to read them from the libgcc file.
any := false
undefs := ctxt.loader.UndefinedRelocTargets(1)
if len(undefs) > 0 {
any = true
}
if any {
if *flagLibGCC == "" {
*flagLibGCC = ctxt.findLibPathCmd("--print-libgcc-file-name", "libgcc")
}
if runtime.GOOS == "openbsd" && *flagLibGCC == "libgcc.a" {
// On OpenBSD `clang --print-libgcc-file-name` returns "libgcc.a".
// In this case we fail to load libgcc.a and can encounter link
// errors - see if we can find libcompiler_rt.a instead.
*flagLibGCC = ctxt.findLibPathCmd("--print-file-name=libcompiler_rt.a", "libcompiler_rt")
}
if *flagLibGCC != "none" {
hostArchive(ctxt, *flagLibGCC)
}
if ctxt.HeadType == objabi.Hwindows {
if p := ctxt.findLibPath("libmingwex.a"); p != "none" {
hostArchive(ctxt, p)
}
if p := ctxt.findLibPath("libmingw32.a"); p != "none" {
hostArchive(ctxt, p)
}
// Link libmsvcrt.a to resolve '__acrt_iob_func' symbol
// (see https://golang.org/issue/23649 for details).
if p := ctxt.findLibPath("libmsvcrt.a"); p != "none" {
hostArchive(ctxt, p)
}
// TODO: maybe do something similar to peimporteddlls to collect all lib names
// and try link them all to final exe just like libmingwex.a and libmingw32.a:
/*
for:
#cgo windows LDFLAGS: -lmsvcrt -lm
import:
libmsvcrt.a libm.a
*/
}
}
}
// We've loaded all the code now.
ctxt.Loaded = true
importcycles()
strictDupMsgCount = ctxt.loader.NStrictDupMsgs()
}
// genSymsForDynexp constructs a *sym.Symbol version of ctxt.dynexp,
// writing to the global variable 'dynexp'.
func genSymsForDynexp(ctxt *Link) {
dynexp = make([]*sym.Symbol, len(ctxt.dynexp2))
for i, s := range ctxt.dynexp2 {
dynexp[i] = ctxt.loader.Syms[s]
}
}
// setupdynexp constructs ctxt.dynexp, a list of loader.Sym.
func setupdynexp(ctxt *Link) {
dynexpMap := ctxt.cgo_export_dynamic
if ctxt.LinkMode == LinkExternal {
dynexpMap = ctxt.cgo_export_static
}
d := make([]loader.Sym, 0, len(dynexpMap))
for exp := range dynexpMap {
s := ctxt.loader.LookupOrCreateSym(exp, 0)
d = append(d, s)
// sanity check
if !ctxt.loader.AttrReachable(s) {
panic("dynexp entry not reachable")
}
}
sort.Slice(d, func(i, j int) bool {
return ctxt.loader.SymName(d[i]) < ctxt.loader.SymName(d[j])
})
// Resolve ABI aliases in the list of cgo-exported functions.
// This is necessary because we load the ABI0 symbol for all
// cgo exports.
for i, s := range d {
if ctxt.loader.SymType(s) != sym.SABIALIAS {
continue
}
t := ctxt.loader.ResolveABIAlias(s)
ctxt.loader.CopyAttributes(s, t)
ctxt.loader.SetSymExtname(t, ctxt.loader.SymExtname(s))
d[i] = t
}
ctxt.dynexp2 = d
ctxt.cgo_export_static = nil
ctxt.cgo_export_dynamic = nil
}
// loadcgodirectives reads the previously discovered cgo directives, creating
// symbols in preparation for host object loading or use later in the link.
func (ctxt *Link) loadcgodirectives() {
l := ctxt.loader
hostObjSyms := make(map[loader.Sym]struct{})
for _, d := range ctxt.cgodata {
setCgoAttr(ctxt, ctxt.loader.LookupOrCreateSym, d.file, d.pkg, d.directives, hostObjSyms)
}
ctxt.cgodata = nil
if ctxt.LinkMode == LinkInternal {
// Drop all the cgo_import_static declarations.
// Turns out we won't be needing them.
for symIdx := range hostObjSyms {
if l.SymType(symIdx) == sym.SHOSTOBJ {
// If a symbol was marked both
// cgo_import_static and cgo_import_dynamic,
// then we want to make it cgo_import_dynamic
// now.
su := l.MakeSymbolUpdater(symIdx)
if l.SymExtname(symIdx) != "" && l.SymDynimplib(symIdx) != "" && !(l.AttrCgoExportStatic(symIdx) || l.AttrCgoExportDynamic(symIdx)) {
su.SetType(sym.SDYNIMPORT)
} else {
su.SetType(0)
}
}
}
}
}
// Set up flags and special symbols depending on the platform build mode.
// This version works with loader.Loader.
func (ctxt *Link) linksetup() {
switch ctxt.BuildMode {
case BuildModeCShared, BuildModePlugin:
symIdx := ctxt.loader.LookupOrCreateSym("runtime.islibrary", 0)
sb := ctxt.loader.MakeSymbolUpdater(symIdx)
sb.SetType(sym.SNOPTRDATA)
sb.AddUint8(1)
case BuildModeCArchive:
symIdx := ctxt.loader.LookupOrCreateSym("runtime.isarchive", 0)
sb := ctxt.loader.MakeSymbolUpdater(symIdx)
sb.SetType(sym.SNOPTRDATA)
sb.AddUint8(1)
}
// Recalculate pe parameters now that we have ctxt.LinkMode set.
if ctxt.HeadType == objabi.Hwindows {
Peinit(ctxt)
}
if ctxt.HeadType == objabi.Hdarwin && ctxt.LinkMode == LinkExternal {
*FlagTextAddr = 0
}
// 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 ctxt.BuildMode == BuildModeExe {
if havedynamic == 0 && ctxt.HeadType != objabi.Hdarwin && ctxt.HeadType != objabi.Hsolaris {
*FlagD = true
}
}
if ctxt.LinkMode == LinkExternal && ctxt.Arch.Family == sys.PPC64 && objabi.GOOS != "aix" {
toc := ctxt.loader.LookupOrCreateSym(".TOC.", 0)
sb := ctxt.loader.MakeSymbolUpdater(toc)
sb.SetType(sym.SDYNIMPORT)
}
// The Android Q linker started to complain about underalignment of the our TLS
// section. We don't actually use the section on android, so don't
// generate it.
if objabi.GOOS != "android" {
tlsg := ctxt.loader.LookupOrCreateSym("runtime.tlsg", 0)
sb := ctxt.loader.MakeSymbolUpdater(tlsg)
// runtime.tlsg is used for external linking on platforms that do not define
// a variable to hold g in assembly (currently only intel).
if sb.Type() == 0 {
sb.SetType(sym.STLSBSS)
sb.SetSize(int64(ctxt.Arch.PtrSize))
} else if sb.Type() != sym.SDYNIMPORT {
Errorf(nil, "runtime declared tlsg variable %v", sb.Type())
}
ctxt.loader.SetAttrReachable(tlsg, true)
ctxt.Tlsg2 = tlsg
}
var moduledata loader.Sym
var mdsb *loader.SymbolBuilder
if ctxt.BuildMode == BuildModePlugin {
moduledata = ctxt.loader.LookupOrCreateSym("local.pluginmoduledata", 0)
mdsb = ctxt.loader.MakeSymbolUpdater(moduledata)
ctxt.loader.SetAttrLocal(moduledata, true)
} else {
moduledata = ctxt.loader.LookupOrCreateSym("runtime.firstmoduledata", 0)
mdsb = ctxt.loader.MakeSymbolUpdater(moduledata)
}
if mdsb.Type() != 0 && mdsb.Type() != sym.SDYNIMPORT {
// If the module (toolchain-speak for "executable or shared
// library") we are linking contains the runtime package, it
// will define the runtime.firstmoduledata symbol and we
// truncate it back to 0 bytes so we can define its entire
// contents in symtab.go:symtab().
mdsb.SetSize(0)
// In addition, on ARM, the runtime depends on the linker
// recording the value of GOARM.
if ctxt.Arch.Family == sys.ARM {
goarm := ctxt.loader.LookupOrCreateSym("runtime.goarm", 0)
sb := ctxt.loader.MakeSymbolUpdater(goarm)
sb.SetType(sym.SDATA)
sb.SetSize(0)
sb.AddUint8(uint8(objabi.GOARM))
}
if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
fpe := ctxt.loader.LookupOrCreateSym("runtime.framepointer_enabled", 0)
sb := ctxt.loader.MakeSymbolUpdater(fpe)
sb.SetType(sym.SNOPTRDATA)
sb.SetSize(0)
sb.AddUint8(1)
}
} else {
// If OTOH the module does not contain the runtime package,
// create a local symbol for the moduledata.
moduledata = ctxt.loader.LookupOrCreateSym("local.moduledata", 0)
mdsb = ctxt.loader.MakeSymbolUpdater(moduledata)
ctxt.loader.SetAttrLocal(moduledata, true)
}
// In all cases way we mark the moduledata as noptrdata to hide it from
// the GC.
mdsb.SetType(sym.SNOPTRDATA)
ctxt.loader.SetAttrReachable(moduledata, true)
ctxt.Moduledata2 = moduledata
// If package versioning is required, generate a hash of the
// packages used in the link.
if ctxt.BuildMode == BuildModeShared || ctxt.BuildMode == BuildModePlugin || ctxt.CanUsePlugins() {
for _, lib := range ctxt.Library {
if lib.Shlib == "" {
genhash(ctxt, lib)
}
}
}
if ctxt.Arch == sys.Arch386 && ctxt.HeadType != objabi.Hwindows {
if (ctxt.BuildMode == BuildModeCArchive && ctxt.IsELF) || ctxt.BuildMode == BuildModeCShared || ctxt.BuildMode == BuildModePIE || ctxt.DynlinkingGo() {
got := ctxt.loader.LookupOrCreateSym("_GLOBAL_OFFSET_TABLE_", 0)
sb := ctxt.loader.MakeSymbolUpdater(got)
sb.SetType(sym.SDYNIMPORT)
ctxt.loader.SetAttrReachable(got, true)
}
}
// DWARF-gen and other phases require that the unit Textp2 slices
// be populated, so that it can walk the functions in each unit.
// Call into the loader to do this (requires that we collect the
// set of internal libraries first). NB: might be simpler if we
// moved isRuntimeDepPkg to cmd/internal and then did the test in
// loader.AssignTextSymbolOrder.
ctxt.Library = postorder(ctxt.Library)
intlibs := []bool{}
for _, lib := range ctxt.Library {
intlibs = append(intlibs, isRuntimeDepPkg(lib.Pkg))
}
ctxt.Textp2 = ctxt.loader.AssignTextSymbolOrder(ctxt.Library, intlibs, ctxt.Textp2)
}
// mangleTypeSym shortens the names of symbols that represent Go types
// if they are visible in the symbol table.
//
// As the names of these symbols are derived from the string of
// the type, they can run to many kilobytes long. So we shorten
// them using a SHA-1 when the name appears in the final binary.
// This also removes characters that upset external linkers.
//
// These are the symbols that begin with the prefix 'type.' and
// contain run-time type information used by the runtime and reflect
// packages. All Go binaries contain these symbols, but only
// those programs loaded dynamically in multiple parts need these
// symbols to have entries in the symbol table.
func (ctxt *Link) mangleTypeSym() {
if ctxt.BuildMode != BuildModeShared && !ctxt.linkShared && ctxt.BuildMode != BuildModePlugin && !ctxt.CanUsePlugins() {
return
}
ldr := ctxt.loader
for s := loader.Sym(1); s < loader.Sym(ldr.NSym()); s++ {
if !ldr.AttrReachable(s) {
continue
}
name := ldr.SymName(s)
newName := typeSymbolMangle(name)
if newName != name {
ldr.SetSymExtname(s, newName)
// When linking against a shared library, the Go object file may
// have reference to the original symbol name whereas the shared
// library provides a symbol with the mangled name. We need to
// copy the payload of mangled to original.
// XXX maybe there is a better way to do this.
dup := ldr.Lookup(newName, ldr.SymVersion(s))
if dup != 0 {
st := ldr.SymType(s)
dt := ldr.SymType(dup)
if st == sym.Sxxx && dt != sym.Sxxx {
ldr.CopySym(dup, s)
}
}
}
}
}
// typeSymbolMangle mangles the given symbol name into something shorter.
//
// Keep the type.. prefix, which parts of the linker (like the
// DWARF generator) know means the symbol is not decodable.
// Leave type.runtime. symbols alone, because other parts of
// the linker manipulates them.
func typeSymbolMangle(name string) string {
if !strings.HasPrefix(name, "type.") {
return name
}
if strings.HasPrefix(name, "type.runtime.") {
return name
}
if len(name) <= 14 && !strings.Contains(name, "@") { // Issue 19529
return name
}
hash := sha1.Sum([]byte(name))
prefix := "type."
if name[5] == '.' {
prefix = "type.."
}
return prefix + base64.StdEncoding.EncodeToString(hash[:6])
}
/*
* look for the next file in an archive.
* adapted from libmach.
*/
func nextar(bp *bio.Reader, off int64, a *ArHdr) int64 {
if off&1 != 0 {
off++
}
bp.MustSeek(off, 0)
var buf [SAR_HDR]byte
if n, err := io.ReadFull(bp, buf[:]); err != nil {
if n == 0 && err != io.EOF {
return -1
}
return 0
}
a.name = artrim(buf[0:16])
a.date = artrim(buf[16:28])
a.uid = artrim(buf[28:34])
a.gid = artrim(buf[34:40])
a.mode = artrim(buf[40:48])
a.size = artrim(buf[48:58])
a.fmag = artrim(buf[58:60])
arsize := atolwhex(a.size)
if arsize&1 != 0 {
arsize++
}
return arsize + SAR_HDR
}
func genhash(ctxt *Link, lib *sym.Library) {
f, err := bio.Open(lib.File)
if err != nil {
Errorf(nil, "cannot open file %s for hash generation: %v", lib.File, err)
return
}
defer f.Close()
var magbuf [len(ARMAG)]byte
if _, err := io.ReadFull(f, magbuf[:]); err != nil {
Exitf("file %s too short", lib.File)
}
if string(magbuf[:]) != ARMAG {
Exitf("%s is not an archive file", lib.File)
}
var arhdr ArHdr
l := nextar(f, f.Offset(), &arhdr)
if l <= 0 {
Errorf(nil, "%s: short read on archive file symbol header", lib.File)
return
}
if arhdr.name != pkgdef {
Errorf(nil, "%s: missing package data entry", lib.File)
return
}
h := sha1.New()
// To compute the hash of a package, we hash the first line of
// __.PKGDEF (which contains the toolchain version and any
// GOEXPERIMENT flags) and the export data (which is between
// the first two occurrences of "\n$$").
pkgDefBytes := make([]byte, atolwhex(arhdr.size))
_, err = io.ReadFull(f, pkgDefBytes)
if err != nil {
Errorf(nil, "%s: error reading package data: %v", lib.File, err)
return
}
firstEOL := bytes.IndexByte(pkgDefBytes, '\n')
if firstEOL < 0 {
Errorf(nil, "cannot parse package data of %s for hash generation, no newline found", lib.File)
return
}
firstDoubleDollar := bytes.Index(pkgDefBytes, []byte("\n$$"))
if firstDoubleDollar < 0 {
Errorf(nil, "cannot parse package data of %s for hash generation, no \\n$$ found", lib.File)
return
}
secondDoubleDollar := bytes.Index(pkgDefBytes[firstDoubleDollar+1:], []byte("\n$$"))
if secondDoubleDollar < 0 {
Errorf(nil, "cannot parse package data of %s for hash generation, only one \\n$$ found", lib.File)
return
}
h.Write(pkgDefBytes[0:firstEOL])
h.Write(pkgDefBytes[firstDoubleDollar : firstDoubleDollar+secondDoubleDollar])
lib.Hash = hex.EncodeToString(h.Sum(nil))
}
func loadobjfile(ctxt *Link, lib *sym.Library) {
pkg := objabi.PathToPrefix(lib.Pkg)
if ctxt.Debugvlog > 1 {
ctxt.Logf("ldobj: %s (%s)\n", lib.File, pkg)
}
f, err := bio.Open(lib.File)
if err != nil {
Exitf("cannot open file %s: %v", lib.File, err)
}
defer f.Close()
defer func() {
if pkg == "main" && !lib.Main {
Exitf("%s: not package main", lib.File)
}
// Ideally, we'd check that *all* object files within
// the archive were marked safe, but here we settle
// for *any*.
//
// Historically, cmd/link only checked the __.PKGDEF
// file, which in turn came from the first object
// file, typically produced by cmd/compile. The
// remaining object files are normally produced by
// cmd/asm, which doesn't support marking files as
// safe anyway. So at least in practice, this matches
// how safe mode has always worked.
if *flagU && !lib.Safe {
Exitf("%s: load of unsafe package %s", lib.File, pkg)
}
}()
for i := 0; i < len(ARMAG); i++ {
if c, err := f.ReadByte(); err == nil && c == ARMAG[i] {
continue
}
/* load it as a regular file */
l := f.MustSeek(0, 2)
f.MustSeek(0, 0)
ldobj(ctxt, f, lib, l, lib.File, lib.File)
return
}
/*
* 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 __.PKGDEF.
*/
var arhdr ArHdr
off := f.Offset()
for {
l := nextar(f, off, &arhdr)
if l == 0 {
break
}
if l < 0 {
Exitf("%s: malformed archive", lib.File)
}
off += l
// __.PKGDEF isn't a real Go object file, and it's
// absent in -linkobj builds anyway. Skipping it
// ensures consistency between -linkobj and normal
// build modes.
if arhdr.name == pkgdef {
continue
}
// Skip other special (non-object-file) sections that
// build tools may have added. Such sections must have
// short names so that the suffix is not truncated.
if len(arhdr.name) < 16 {
if ext := filepath.Ext(arhdr.name); ext != ".o" && ext != ".syso" {
continue
}
}
pname := fmt.Sprintf("%s(%s)", lib.File, arhdr.name)
l = atolwhex(arhdr.size)
ldobj(ctxt, f, lib, l, pname, lib.File)
}
}
type Hostobj struct {
ld func(*Link, *bio.Reader, string, int64, string)
pkg string
pn string
file string
off int64
length int64
}
var hostobj []Hostobj
// These packages can use internal linking mode.
// Others trigger external mode.
var internalpkg = []string{
"crypto/x509",
"net",
"os/user",
"runtime/cgo",
"runtime/race",
"runtime/msan",
}
func ldhostobj(ld func(*Link, *bio.Reader, string, int64, string), headType objabi.HeadType, f *bio.Reader, pkg string, length int64, pn string, file string) *Hostobj {
isinternal := false
for _, intpkg := range internalpkg {
if pkg == intpkg {
isinternal = true
break
}
}
// DragonFly declares errno with __thread, which results in a symbol
// type of R_386_TLS_GD or R_X86_64_TLSGD. The Go linker does not
// currently know how to handle TLS relocations, hence we have to
// force external linking for any libraries that link in code that
// uses errno. This can be removed if the Go linker ever supports
// these relocation types.
if headType == objabi.Hdragonfly {
if pkg == "net" || pkg == "os/user" {
isinternal = false
}
}
if !isinternal {
externalobj = true
}
hostobj = append(hostobj, Hostobj{})
h := &hostobj[len(hostobj)-1]
h.ld = ld
h.pkg = pkg
h.pn = pn
h.file = file
h.off = f.Offset()
h.length = length
return h
}
func hostobjs(ctxt *Link) {
if ctxt.LinkMode != LinkInternal {
return
}
var h *Hostobj
for i := 0; i < len(hostobj); i++ {
h = &hostobj[i]
f, err := bio.Open(h.file)
if err != nil {
Exitf("cannot reopen %s: %v", h.pn, err)
}
f.MustSeek(h.off, 0)
h.ld(ctxt, f, h.pkg, h.length, h.pn)
f.Close()
}
}
func hostlinksetup(ctxt *Link) {
if ctxt.LinkMode != LinkExternal {
return
}
// For external link, record that we need to tell the external linker -s,
// and turn off -s internally: the external linker needs the symbol
// information for its final link.
debug_s = *FlagS
*FlagS = false
// create temporary directory and arrange cleanup
if *flagTmpdir == "" {
dir, err := ioutil.TempDir("", "go-link-")
if err != nil {
log.Fatal(err)
}
*flagTmpdir = dir
ownTmpDir = true
AtExit(func() {
ctxt.Out.Close()
os.RemoveAll(*flagTmpdir)
})
}
// change our output to temporary object file
if err := ctxt.Out.Close(); err != nil {
Exitf("error closing output file")
}
mayberemoveoutfile()
p := filepath.Join(*flagTmpdir, "go.o")
if err := ctxt.Out.Open(p); err != nil {
Exitf("cannot create %s: %v", p, err)
}
}
// hostobjCopy creates a copy of the object files in hostobj in a
// temporary directory.
func hostobjCopy() (paths []string) {
var wg sync.WaitGroup
sema := make(chan struct{}, runtime.NumCPU()) // limit open file descriptors
for i, h := range hostobj {
h := h
dst := filepath.Join(*flagTmpdir, fmt.Sprintf("%06d.o", i))
paths = append(paths, dst)
wg.Add(1)
go func() {
sema <- struct{}{}
defer func() {
<-sema
wg.Done()
}()
f, err := os.Open(h.file)
if err != nil {
Exitf("cannot reopen %s: %v", h.pn, err)
}
defer f.Close()
if _, err := f.Seek(h.off, 0); err != nil {
Exitf("cannot seek %s: %v", h.pn, err)
}
w, err := os.Create(dst)
if err != nil {
Exitf("cannot create %s: %v", dst, err)
}
if _, err := io.CopyN(w, f, h.length); err != nil {
Exitf("cannot write %s: %v", dst, err)
}
if err := w.Close(); err != nil {
Exitf("cannot close %s: %v", dst, err)
}
}()
}
wg.Wait()
return paths
}
// writeGDBLinkerScript creates gcc linker script file in temp
// directory. writeGDBLinkerScript returns created file path.
// The script is used to work around gcc bug
// (see https://golang.org/issue/20183 for details).
func writeGDBLinkerScript() string {
name := "fix_debug_gdb_scripts.ld"
path := filepath.Join(*flagTmpdir, name)
src := `SECTIONS
{
.debug_gdb_scripts BLOCK(__section_alignment__) (NOLOAD) :
{
*(.debug_gdb_scripts)
}
}
INSERT AFTER .debug_types;
`
err := ioutil.WriteFile(path, []byte(src), 0666)
if err != nil {
Errorf(nil, "WriteFile %s failed: %v", name, err)
}
return path
}
// archive builds a .a archive from the hostobj object files.
func (ctxt *Link) archive() {
if ctxt.BuildMode != BuildModeCArchive {
return
}
exitIfErrors()
if *flagExtar == "" {
*flagExtar = "ar"
}
mayberemoveoutfile()
// Force the buffer to flush here so that external
// tools will see a complete file.
if err := ctxt.Out.Close(); err != nil {
Exitf("error closing %v", *flagOutfile)
}
argv := []string{*flagExtar, "-q", "-c", "-s"}
if ctxt.HeadType == objabi.Haix {
argv = append(argv, "-X64")
}
argv = append(argv, *flagOutfile)
argv = append(argv, filepath.Join(*flagTmpdir, "go.o"))
argv = append(argv, hostobjCopy()...)
if ctxt.Debugvlog != 0 {
ctxt.Logf("archive: %s\n", strings.Join(argv, " "))
}
// If supported, use syscall.Exec() to invoke the archive command,
// which should be the final remaining step needed for the link.
// This will reduce peak RSS for the link (and speed up linking of
// large applications), since when the archive command runs we
// won't be holding onto all of the linker's live memory.
if syscallExecSupported && !ownTmpDir {
runAtExitFuncs()
ctxt.execArchive(argv)
panic("should not get here")
}
// Otherwise invoke 'ar' in the usual way (fork + exec).
if out, err := exec.Command(argv[0], argv[1:]...).CombinedOutput(); err != nil {
Exitf("running %s failed: %v\n%s", argv[0], err, out)
}
}
func (ctxt *Link) hostlink() {
if ctxt.LinkMode != LinkExternal || nerrors > 0 {
return
}
if ctxt.BuildMode == BuildModeCArchive {
return
}
var argv []string
argv = append(argv, ctxt.extld())
argv = append(argv, hostlinkArchArgs(ctxt.Arch)...)
if *FlagS || debug_s {
if ctxt.HeadType == objabi.Hdarwin {
// Recent versions of macOS print
// ld: warning: option -s is obsolete and being ignored
// so do not pass any arguments.
} else {
argv = append(argv, "-s")
}
}
switch ctxt.HeadType {
case objabi.Hdarwin:
if machoPlatform == PLATFORM_MACOS {
// -headerpad is incompatible with -fembed-bitcode.
argv = append(argv, "-Wl,-headerpad,1144")
}
if ctxt.DynlinkingGo() && !ctxt.Arch.InFamily(sys.ARM, sys.ARM64) {
argv = append(argv, "-Wl,-flat_namespace")
}
case objabi.Hopenbsd:
argv = append(argv, "-Wl,-nopie")
case objabi.Hwindows:
if windowsgui {
argv = append(argv, "-mwindows")
} else {
argv = append(argv, "-mconsole")
}
// Mark as having awareness of terminal services, to avoid
// ancient compatibility hacks.
argv = append(argv, "-Wl,--tsaware")
// Enable DEP
argv = append(argv, "-Wl,--nxcompat")
argv = append(argv, fmt.Sprintf("-Wl,--major-os-version=%d", PeMinimumTargetMajorVersion))
argv = append(argv, fmt.Sprintf("-Wl,--minor-os-version=%d", PeMinimumTargetMinorVersion))
argv = append(argv, fmt.Sprintf("-Wl,--major-subsystem-version=%d", PeMinimumTargetMajorVersion))
argv = append(argv, fmt.Sprintf("-Wl,--minor-subsystem-version=%d", PeMinimumTargetMinorVersion))
case objabi.Haix:
argv = append(argv, "-pthread")
// prevent ld to reorder .text functions to keep the same
// first/last functions for moduledata.
argv = append(argv, "-Wl,-bnoobjreorder")
// mcmodel=large is needed for every gcc generated files, but
// ld still need -bbigtoc in order to allow larger TOC.
argv = append(argv, "-mcmodel=large")
argv = append(argv, "-Wl,-bbigtoc")
}
switch ctxt.BuildMode {
case BuildModeExe:
if ctxt.HeadType == objabi.Hdarwin {
if machoPlatform == PLATFORM_MACOS {
argv = append(argv, "-Wl,-no_pie")
argv = append(argv, "-Wl,-pagezero_size,4000000")
}
}
case BuildModePIE:
switch ctxt.HeadType {
case objabi.Hdarwin, objabi.Haix:
case objabi.Hwindows:
// Enable ASLR.
argv = append(argv, "-Wl,--dynamicbase")
// enable high-entropy ASLR on 64-bit.
if ctxt.Arch.PtrSize >= 8 {
argv = append(argv, "-Wl,--high-entropy-va")
}
// Work around binutils limitation that strips relocation table for dynamicbase.
// See https://sourceware.org/bugzilla/show_bug.cgi?id=19011
argv = append(argv, "-Wl,--export-all-symbols")
default:
// ELF.
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
}
argv = append(argv, "-pie")
}
case BuildModeCShared:
if ctxt.HeadType == objabi.Hdarwin {
argv = append(argv, "-dynamiclib")
if ctxt.Arch.Family != sys.AMD64 {
argv = append(argv, "-Wl,-read_only_relocs,suppress")
}
} else {
// ELF.
argv = append(argv, "-Wl,-Bsymbolic")
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
}
argv = append(argv, "-shared")
if ctxt.HeadType != objabi.Hwindows {
// Pass -z nodelete to mark the shared library as
// non-closeable: a dlclose will do nothing.
argv = append(argv, "-Wl,-z,nodelete")
}
}
case BuildModeShared:
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
}
argv = append(argv, "-shared")
case BuildModePlugin:
if ctxt.HeadType == objabi.Hdarwin {
argv = append(argv, "-dynamiclib")
} else {
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
}
argv = append(argv, "-shared")
}
}
if ctxt.IsELF && ctxt.DynlinkingGo() {
// We force all symbol resolution to be done at program startup
// because lazy PLT resolution can use large amounts of stack at
// times we cannot allow it to do so.
argv = append(argv, "-Wl,-znow")
// Do not let the host linker generate COPY relocations. These
// can move symbols out of sections that rely on stable offsets
// from the beginning of the section (like sym.STYPE).
argv = append(argv, "-Wl,-znocopyreloc")
if ctxt.Arch.InFamily(sys.ARM, sys.ARM64) && objabi.GOOS == "linux" {
// On ARM, the GNU linker will generate COPY relocations
// even with -znocopyreloc set.
// https://sourceware.org/bugzilla/show_bug.cgi?id=19962
//
// On ARM64, the GNU linker will fail instead of
// generating COPY relocations.
//
// In both cases, switch to gold.
argv = append(argv, "-fuse-ld=gold")
// If gold is not installed, gcc will silently switch
// back to ld.bfd. So we parse the version information
// and provide a useful error if gold is missing.
cmd := exec.Command(*flagExtld, "-fuse-ld=gold", "-Wl,--version")
if out, err := cmd.CombinedOutput(); err == nil {
if !bytes.Contains(out, []byte("GNU gold")) {
log.Fatalf("ARM external linker must be gold (issue #15696), but is not: %s", out)
}
}
}
}
if ctxt.Arch.Family == sys.ARM64 && objabi.GOOS == "freebsd" {
// Switch to ld.bfd on freebsd/arm64.
argv = append(argv, "-fuse-ld=bfd")
// Provide a useful error if ld.bfd is missing.
cmd := exec.Command(*flagExtld, "-fuse-ld=bfd", "-Wl,--version")
if out, err := cmd.CombinedOutput(); err == nil {
if !bytes.Contains(out, []byte("GNU ld")) {
log.Fatalf("ARM64 external linker must be ld.bfd (issue #35197), please install devel/binutils")
}
}
}
if ctxt.IsELF && len(buildinfo) > 0 {
argv = append(argv, fmt.Sprintf("-Wl,--build-id=0x%x", buildinfo))
}
// On Windows, given -o foo, GCC will append ".exe" to produce
// "foo.exe". We have decided that we want to honor the -o
// option. To make this work, we append a '.' so that GCC
// will decide that the file already has an extension. We
// only want to do this when producing a Windows output file
// on a Windows host.
outopt := *flagOutfile
if objabi.GOOS == "windows" && runtime.GOOS == "windows" && filepath.Ext(outopt) == "" {
outopt += "."
}
argv = append(argv, "-o")
argv = append(argv, outopt)
if rpath.val != "" {
argv = append(argv, fmt.Sprintf("-Wl,-rpath,%s", rpath.val))
}
// Force global symbols to be exported for dlopen, etc.
if ctxt.IsELF {
argv = append(argv, "-rdynamic")
}
if ctxt.HeadType == objabi.Haix {
fileName := xcoffCreateExportFile(ctxt)
argv = append(argv, "-Wl,-bE:"+fileName)
}
if strings.Contains(argv[0], "clang") {
argv = append(argv, "-Qunused-arguments")
}
const compressDWARF = "-Wl,--compress-debug-sections=zlib-gnu"
if ctxt.compressDWARF && linkerFlagSupported(argv[0], compressDWARF) {
argv = append(argv, compressDWARF)
}
argv = append(argv, filepath.Join(*flagTmpdir, "go.o"))
argv = append(argv, hostobjCopy()...)
if ctxt.HeadType == objabi.Haix {
// We want to have C files after Go files to remove
// trampolines csects made by ld.
argv = append(argv, "-nostartfiles")
argv = append(argv, "/lib/crt0_64.o")
extld := ctxt.extld()
// Get starting files.
getPathFile := func(file string) string {
args := []string{"-maix64", "--print-file-name=" + file}
out, err := exec.Command(extld, args...).CombinedOutput()
if err != nil {
log.Fatalf("running %s failed: %v\n%s", extld, err, out)
}
return strings.Trim(string(out), "\n")
}
argv = append(argv, getPathFile("crtcxa.o"))
argv = append(argv, getPathFile("crtdbase.o"))
}
if ctxt.linkShared {
seenDirs := make(map[string]bool)
seenLibs := make(map[string]bool)
addshlib := func(path string) {
dir, base := filepath.Split(path)
if !seenDirs[dir] {
argv = append(argv, "-L"+dir)
if !rpath.set {
argv = append(argv, "-Wl,-rpath="+dir)
}
seenDirs[dir] = true
}
base = strings.TrimSuffix(base, ".so")
base = strings.TrimPrefix(base, "lib")
if !seenLibs[base] {
argv = append(argv, "-l"+base)
seenLibs[base] = true
}
}
for _, shlib := range ctxt.Shlibs {
addshlib(shlib.Path)
for _, dep := range shlib.Deps {
if dep == "" {
continue
}
libpath := findshlib(ctxt, dep)
if libpath != "" {
addshlib(libpath)
}
}
}
}
// clang, unlike GCC, passes -rdynamic to the linker
// even when linking with -static, causing a linker
// error when using GNU ld. So take out -rdynamic if
// we added it. We do it in this order, rather than
// only adding -rdynamic later, so that -*extldflags
// can override -rdynamic without using -static.
checkStatic := func(arg string) {
if ctxt.IsELF && arg == "-static" {
for i := range argv {
if argv[i] == "-rdynamic" {
argv[i] = "-static"
}
}
}
}
for _, p := range ldflag {
argv = append(argv, p)
checkStatic(p)
}
// When building a program with the default -buildmode=exe the
// gc compiler generates code requires DT_TEXTREL in a
// position independent executable (PIE). On systems where the
// toolchain creates PIEs by default, and where DT_TEXTREL
// does not work, the resulting programs will not run. See
// issue #17847. To avoid this problem pass -no-pie to the
// toolchain if it is supported.
if ctxt.BuildMode == BuildModeExe && !ctxt.linkShared {
// GCC uses -no-pie, clang uses -nopie.
for _, nopie := range []string{"-no-pie", "-nopie"} {
if linkerFlagSupported(argv[0], nopie) {
argv = append(argv, nopie)
break
}
}
}
for _, p := range strings.Fields(*flagExtldflags) {
argv = append(argv, p)
checkStatic(p)
}
if ctxt.HeadType == objabi.Hwindows {
// use gcc linker script to work around gcc bug
// (see https://golang.org/issue/20183 for details).
p := writeGDBLinkerScript()
argv = append(argv, "-Wl,-T,"+p)
// libmingw32 and libmingwex have some inter-dependencies,
// so must use linker groups.
argv = append(argv, "-Wl,--start-group", "-lmingwex", "-lmingw32", "-Wl,--end-group")
argv = append(argv, peimporteddlls()...)
}
if ctxt.Debugvlog != 0 {
ctxt.Logf("host link:")
for _, v := range argv {
ctxt.Logf(" %q", v)
}
ctxt.Logf("\n")
}
out, err := exec.Command(argv[0], argv[1:]...).CombinedOutput()
if err != nil {
Exitf("running %s failed: %v\n%s", argv[0], err, out)
}
// Filter out useless linker warnings caused by bugs outside Go.
// See also cmd/go/internal/work/exec.go's gccld method.
var save [][]byte
var skipLines int
for _, line := range bytes.SplitAfter(out, []byte("\n")) {
// golang.org/issue/26073 - Apple Xcode bug
if bytes.Contains(line, []byte("ld: warning: text-based stub file")) {
continue
}
if skipLines > 0 {
skipLines--
continue
}
// Remove TOC overflow warning on AIX.
if bytes.Contains(line, []byte("ld: 0711-783")) {
skipLines = 2
continue
}
save = append(save, line)
}
out = bytes.Join(save, nil)
if len(out) > 0 {
// always print external output even if the command is successful, so that we don't
// swallow linker warnings (see https://golang.org/issue/17935).
ctxt.Logf("%s", out)
}
if !*FlagS && !*FlagW && !debug_s && ctxt.HeadType == objabi.Hdarwin {
dsym := filepath.Join(*flagTmpdir, "go.dwarf")
if out, err := exec.Command("dsymutil", "-f", *flagOutfile, "-o", dsym).CombinedOutput(); err != nil {
Exitf("%s: running dsymutil failed: %v\n%s", os.Args[0], err, out)
}
// Skip combining if `dsymutil` didn't generate a file. See #11994.
if _, err := os.Stat(dsym); os.IsNotExist(err) {
return
}
// For os.Rename to work reliably, must be in same directory as outfile.
combinedOutput := *flagOutfile + "~"
exef, err := os.Open(*flagOutfile)
if err != nil {
Exitf("%s: combining dwarf failed: %v", os.Args[0], err)
}
defer exef.Close()
exem, err := macho.NewFile(exef)
if err != nil {
Exitf("%s: parsing Mach-O header failed: %v", os.Args[0], err)
}
// Only macOS supports unmapped segments such as our __DWARF segment.
if machoPlatform == PLATFORM_MACOS {
if err := machoCombineDwarf(ctxt, exef, exem, dsym, combinedOutput); err != nil {
Exitf("%s: combining dwarf failed: %v", os.Args[0], err)
}
os.Remove(*flagOutfile)
if err := os.Rename(combinedOutput, *flagOutfile); err != nil {
Exitf("%s: %v", os.Args[0], err)
}
}
}
}
var createTrivialCOnce sync.Once
func linkerFlagSupported(linker, flag string) bool {
createTrivialCOnce.Do(func() {
src := filepath.Join(*flagTmpdir, "trivial.c")
if err := ioutil.WriteFile(src, []byte("int main() { return 0; }"), 0666); err != nil {
Errorf(nil, "WriteFile trivial.c failed: %v", err)
}
})
flagsWithNextArgSkip := []string{
"-F",
"-l",
"-L",
"-framework",
"-Wl,-framework",
"-Wl,-rpath",
"-Wl,-undefined",
}
flagsWithNextArgKeep := []string{
"-arch",
"-isysroot",
"--sysroot",
"-target",
}
prefixesToKeep := []string{
"-f",
"-m",
"-p",
"-Wl,",
"-arch",
"-isysroot",
"--sysroot",
"-target",
}
var flags []string
keep := false
skip := false
extldflags := strings.Fields(*flagExtldflags)
for _, f := range append(extldflags, ldflag...) {
if keep {
flags = append(flags, f)
keep = false
} else if skip {
skip = false
} else if f == "" || f[0] != '-' {
} else if contains(flagsWithNextArgSkip, f) {
skip = true
} else if contains(flagsWithNextArgKeep, f) {
flags = append(flags, f)
keep = true
} else {
for _, p := range prefixesToKeep {
if strings.HasPrefix(f, p) {
flags = append(flags, f)
break
}
}
}
}
flags = append(flags, flag, "trivial.c")
cmd := exec.Command(linker, flags...)
cmd.Dir = *flagTmpdir
cmd.Env = append([]string{"LC_ALL=C"}, os.Environ()...)
out, err := cmd.CombinedOutput()
// GCC says "unrecognized command line option ‘-no-pie’"
// clang says "unknown argument: '-no-pie'"
return err == nil && !bytes.Contains(out, []byte("unrecognized")) && !bytes.Contains(out, []byte("unknown"))
}
// hostlinkArchArgs returns arguments to pass to the external linker
// based on the architecture.
func hostlinkArchArgs(arch *sys.Arch) []string {
switch arch.Family {
case sys.I386:
return []string{"-m32"}
case sys.AMD64, sys.S390X:
return []string{"-m64"}
case sys.ARM:
return []string{"-marm"}
case sys.ARM64:
// nothing needed
case sys.MIPS64:
return []string{"-mabi=64"}
case sys.MIPS:
return []string{"-mabi=32"}
case sys.PPC64:
if objabi.GOOS == "aix" {
return []string{"-maix64"}
} else {
return []string{"-m64"}
}
}
return nil
}
// ldobj loads an input object. If it is a host object (an object
// compiled by a non-Go compiler) it returns the Hostobj pointer. If
// it is a Go object, it returns nil.
func ldobj(ctxt *Link, f *bio.Reader, lib *sym.Library, length int64, pn string, file string) *Hostobj {
pkg := objabi.PathToPrefix(lib.Pkg)
eof := f.Offset() + length
start := f.Offset()
c1 := bgetc(f)
c2 := bgetc(f)
c3 := bgetc(f)
c4 := bgetc(f)
f.MustSeek(start, 0)
unit := &sym.CompilationUnit{Lib: lib}
lib.Units = append(lib.Units, unit)
magic := uint32(c1)<<24 | uint32(c2)<<16 | uint32(c3)<<8 | uint32(c4)
if magic == 0x7f454c46 { // \x7F E L F
ldelf := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
textp, flags, err := loadelf.Load(ctxt.loader, ctxt.Arch, ctxt.Syms.IncVersion(), f, pkg, length, pn, ehdr.flags)
if err != nil {
Errorf(nil, "%v", err)
return
}
ehdr.flags = flags
ctxt.Textp2 = append(ctxt.Textp2, textp...)
}
return ldhostobj(ldelf, ctxt.HeadType, f, pkg, length, pn, file)
}
if magic&^1 == 0xfeedface || magic&^0x01000000 == 0xcefaedfe {
ldmacho := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
textp, err := loadmacho.Load(ctxt.loader, ctxt.Arch, ctxt.Syms.IncVersion(), f, pkg, length, pn)
if err != nil {
Errorf(nil, "%v", err)
return
}
ctxt.Textp2 = append(ctxt.Textp2, textp...)
}
return ldhostobj(ldmacho, ctxt.HeadType, f, pkg, length, pn, file)
}
if c1 == 0x4c && c2 == 0x01 || c1 == 0x64 && c2 == 0x86 {
ldpe := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
textp, rsrc, err := loadpe.Load(ctxt.loader, ctxt.Arch, ctxt.Syms.IncVersion(), f, pkg, length, pn)
if err != nil {
Errorf(nil, "%v", err)
return
}
if rsrc != 0 {
setpersrc(ctxt, rsrc)
}
ctxt.Textp2 = append(ctxt.Textp2, textp...)
}
return ldhostobj(ldpe, ctxt.HeadType, f, pkg, length, pn, file)
}
if c1 == 0x01 && (c2 == 0xD7 || c2 == 0xF7) {
ldxcoff := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
textp, err := loadxcoff.Load(ctxt.loader, ctxt.Arch, ctxt.Syms.IncVersion(), f, pkg, length, pn)
if err != nil {
Errorf(nil, "%v", err)
return
}
ctxt.Textp2 = append(ctxt.Textp2, textp...)
}
return ldhostobj(ldxcoff, ctxt.HeadType, f, pkg, length, pn, file)
}
/* check the header */
line, err := f.ReadString('\n')
if err != nil {
Errorf(nil, "truncated object file: %s: %v", pn, err)
return nil
}
if !strings.HasPrefix(line, "go object ") {
if strings.HasSuffix(pn, ".go") {
Exitf("%s: uncompiled .go source file", pn)
return nil
}
if line == ctxt.Arch.Name {
// old header format: just $GOOS
Errorf(nil, "%s: stale object file", pn)
return nil
}
Errorf(nil, "%s: not an object file", pn)
return nil
}
// First, check that the basic GOOS, GOARCH, and Version match.
t := fmt.Sprintf("%s %s %s ", objabi.GOOS, objabi.GOARCH, objabi.Version)
line = strings.TrimRight(line, "\n")
if !strings.HasPrefix(line[10:]+" ", t) && !*flagF {
Errorf(nil, "%s: object is [%s] expected [%s]", pn, line[10:], t)
return nil
}
// Second, check that longer lines match each other exactly,
// so that the Go compiler and write additional information
// that must be the same from run to run.
if len(line) >= len(t)+10 {
if theline == "" {
theline = line[10:]
} else if theline != line[10:] {
Errorf(nil, "%s: object is [%s] expected [%s]", pn, line[10:], theline)
return nil
}
}
// Skip over exports and other info -- ends with \n!\n.
//
// Note: It's possible for "\n!\n" to appear within the binary
// package export data format. To avoid truncating the package
// definition prematurely (issue 21703), we keep track of
// how many "$$" delimiters we've seen.
import0 := f.Offset()
c1 = '\n' // the last line ended in \n
c2 = bgetc(f)
c3 = bgetc(f)
markers := 0
for {
if c1 == '\n' {
if markers%2 == 0 && c2 == '!' && c3 == '\n' {
break
}
if c2 == '$' && c3 == '$' {
markers++
}
}
c1 = c2
c2 = c3
c3 = bgetc(f)
if c3 == -1 {
Errorf(nil, "truncated object file: %s", pn)
return nil
}
}
import1 := f.Offset()
f.MustSeek(import0, 0)
ldpkg(ctxt, f, lib, import1-import0-2, pn) // -2 for !\n
f.MustSeek(import1, 0)
fingerprint := ctxt.loader.Preload(ctxt.Syms, f, lib, unit, eof-f.Offset())
if !fingerprint.IsZero() { // Assembly objects don't have fingerprints. Ignore them.
// Check fingerprint, to ensure the importing and imported packages
// have consistent view of symbol indices.
// Normally the go command should ensure this. But in case something
// goes wrong, it could lead to obscure bugs like run-time crash.
// Check it here to be sure.
if lib.Fingerprint.IsZero() { // Not yet imported. Update its fingerprint.
lib.Fingerprint = fingerprint
}
checkFingerprint(lib, fingerprint, lib.Srcref, lib.Fingerprint)
}
addImports(ctxt, lib, pn)
return nil
}
func checkFingerprint(lib *sym.Library, libfp goobj2.FingerprintType, src string, srcfp goobj2.FingerprintType) {
if libfp != srcfp {
Exitf("fingerprint mismatch: %s has %x, import from %s expecting %x", lib, libfp, src, srcfp)
}
}
func readelfsymboldata(ctxt *Link, f *elf.File, sym *elf.Symbol) []byte {
data := make([]byte, sym.Size)
sect := f.Sections[sym.Section]
if sect.Type != elf.SHT_PROGBITS && sect.Type != elf.SHT_NOTE {
Errorf(nil, "reading %s from non-data section", sym.Name)
}
n, err := sect.ReadAt(data, int64(sym.Value-sect.Addr))
if uint64(n) != sym.Size {
Errorf(nil, "reading contents of %s: %v", sym.Name, err)
}
return data
}
func readwithpad(r io.Reader, sz int32) ([]byte, error) {
data := make([]byte, Rnd(int64(sz), 4))
_, err := io.ReadFull(r, data)
if err != nil {
return nil, err
}
data = data[:sz]
return data, nil
}
func readnote(f *elf.File, name []byte, typ int32) ([]byte, error) {
for _, sect := range f.Sections {
if sect.Type != elf.SHT_NOTE {
continue
}
r := sect.Open()
for {
var namesize, descsize, noteType int32
err := binary.Read(r, f.ByteOrder, &namesize)
if err != nil {
if err == io.EOF {
break
}
return nil, fmt.Errorf("read namesize failed: %v", err)
}
err = binary.Read(r, f.ByteOrder, &descsize)
if err != nil {
return nil, fmt.Errorf("read descsize failed: %v", err)
}
err = binary.Read(r, f.ByteOrder, &noteType)
if err != nil {
return nil, fmt.Errorf("read type failed: %v", err)
}
noteName, err := readwithpad(r, namesize)
if err != nil {
return nil, fmt.Errorf("read name failed: %v", err)
}
desc, err := readwithpad(r, descsize)
if err != nil {
return nil, fmt.Errorf("read desc failed: %v", err)
}
if string(name) == string(noteName) && typ == noteType {
return desc, nil
}
}
}
return nil, nil
}
func findshlib(ctxt *Link, shlib string) string {
if filepath.IsAbs(shlib) {
return shlib
}
for _, libdir := range ctxt.Libdir {
libpath := filepath.Join(libdir, shlib)
if _, err := os.Stat(libpath); err == nil {
return libpath
}
}
Errorf(nil, "cannot find shared library: %s", shlib)
return ""
}
func ldshlibsyms(ctxt *Link, shlib string) {
var libpath string
if filepath.IsAbs(shlib) {
libpath = shlib
shlib = filepath.Base(shlib)
} else {
libpath = findshlib(ctxt, shlib)
if libpath == "" {
return
}
}
for _, processedlib := range ctxt.Shlibs {
if processedlib.Path == libpath {
return
}
}
if ctxt.Debugvlog > 1 {
ctxt.Logf("ldshlibsyms: found library with name %s at %s\n", shlib, libpath)
}
f, err := elf.Open(libpath)
if err != nil {
Errorf(nil, "cannot open shared library: %s", libpath)
return
}
defer f.Close()
hash, err := readnote(f, ELF_NOTE_GO_NAME, ELF_NOTE_GOABIHASH_TAG)
if err != nil {
Errorf(nil, "cannot read ABI hash from shared library %s: %v", libpath, err)
return
}
depsbytes, err := readnote(f, ELF_NOTE_GO_NAME, ELF_NOTE_GODEPS_TAG)
if err != nil {
Errorf(nil, "cannot read dep list from shared library %s: %v", libpath, err)
return
}
var deps []string
for _, dep := range strings.Split(string(depsbytes), "\n") {
if dep == "" {
continue
}
if !filepath.IsAbs(dep) {
// If the dep can be interpreted as a path relative to the shlib
// in which it was found, do that. Otherwise, we will leave it
// to be resolved by libdir lookup.
abs := filepath.Join(filepath.Dir(libpath), dep)
if _, err := os.Stat(abs); err == nil {
dep = abs
}
}
deps = append(deps, dep)
}
syms, err := f.DynamicSymbols()
if err != nil {
Errorf(nil, "cannot read symbols from shared library: %s", libpath)
return
}
gcdataLocations := make(map[uint64]loader.Sym)
for _, elfsym := range syms {
if elf.ST_TYPE(elfsym.Info) == elf.STT_NOTYPE || elf.ST_TYPE(elfsym.Info) == elf.STT_SECTION {
continue
}
// Symbols whose names start with "type." are compiler
// generated, so make functions with that prefix internal.
ver := 0
if elf.ST_TYPE(elfsym.Info) == elf.STT_FUNC && strings.HasPrefix(elfsym.Name, "type.") {
ver = sym.SymVerABIInternal
}
l := ctxt.loader
s := l.LookupOrCreateSym(elfsym.Name, ver)
// Because loadlib above loads all .a files before loading
// any shared libraries, any non-dynimport symbols we find
// that duplicate symbols already loaded should be ignored
// (the symbols from the .a files "win").
if l.SymType(s) != 0 && l.SymType(s) != sym.SDYNIMPORT {
continue
}
su := l.MakeSymbolUpdater(s)
su.SetType(sym.SDYNIMPORT)
l.SetSymElfType(s, elf.ST_TYPE(elfsym.Info))
su.SetSize(int64(elfsym.Size))
if elfsym.Section != elf.SHN_UNDEF {
// If it's not undefined, mark the symbol as reachable
// so as to protect it from dead code elimination,
// even if there aren't any explicit references to it.
// Under the previous sym.Symbol based regime this
// wasn't necessary, but for the loader-based deadcode
// it is definitely needed.
//
// FIXME: have a more general/flexible mechanism for this?
//
l.SetAttrReachable(s, true)
// Set .File for the library that actually defines the symbol.
l.SetSymPkg(s, libpath)
// The decodetype_* functions in decodetype.go need access to
// the type data.
sname := l.SymName(s)
if strings.HasPrefix(sname, "type.") && !strings.HasPrefix(sname, "type..") {
su.SetData(readelfsymboldata(ctxt, f, &elfsym))
gcdataLocations[elfsym.Value+2*uint64(ctxt.Arch.PtrSize)+8+1*uint64(ctxt.Arch.PtrSize)] = s
}
}
// For function symbols, we don't know what ABI is
// available, so alias it under both ABIs.
//
// TODO(austin): This is almost certainly wrong once
// the ABIs are actually different. We might have to
// mangle Go function names in the .so to include the
// ABI.
if elf.ST_TYPE(elfsym.Info) == elf.STT_FUNC && ver == 0 {
alias := ctxt.loader.LookupOrCreateSym(elfsym.Name, sym.SymVerABIInternal)
if l.SymType(alias) != 0 {
continue
}
su := l.MakeSymbolUpdater(alias)
su.SetType(sym.SABIALIAS)
su.AddReloc(loader.Reloc{Sym: s})
}
}
if ctxt.Arch.Family == sys.ARM64 {
for _, sect := range f.Sections {
if sect.Type == elf.SHT_RELA {
var rela elf.Rela64
rdr := sect.Open()
for {
err := binary.Read(rdr, f.ByteOrder, &rela)
if err == io.EOF {
break
} else if err != nil {
Errorf(nil, "reading relocation failed %v", err)
return
}
t := elf.R_AARCH64(rela.Info & 0xffff)
if t != elf.R_AARCH64_RELATIVE {
continue
}
}
}
}
}
ctxt.Shlibs = append(ctxt.Shlibs, Shlib{Path: libpath, Hash: hash, Deps: deps, File: f})
}
func addsection(ldr *loader.Loader, arch *sys.Arch, seg *sym.Segment, name string, rwx int) *sym.Section {
sect := ldr.NewSection()
sect.Rwx = uint8(rwx)
sect.Name = name
sect.Seg = seg
sect.Align = int32(arch.PtrSize) // everything is at least pointer-aligned
seg.Sections = append(seg.Sections, sect)
return sect
}
type chain struct {
sym loader.Sym
up *chain
limit int // limit on entry to sym
}
func haslinkregister(ctxt *Link) bool {
return ctxt.FixedFrameSize() != 0
}
func callsize(ctxt *Link) int {
if haslinkregister(ctxt) {
return 0
}
return ctxt.Arch.RegSize
}
type stkChk struct {
ldr *loader.Loader
ctxt *Link
morestack loader.Sym
done loader.Bitmap
}
// Walk the call tree and check that there is always enough stack space
// for the call frames, especially for a chain of nosplit functions.
func (ctxt *Link) dostkcheck() {
ldr := ctxt.loader
sc := stkChk{
ldr: ldr,
ctxt: ctxt,
morestack: ldr.Lookup("runtime.morestack", 0),
done: loader.MakeBitmap(ldr.NSym()),
}
// Every splitting function ensures that there are at least StackLimit
// bytes available below SP when the splitting prologue finishes.
// If the splitting function calls F, then F begins execution with
// at least StackLimit - callsize() bytes available.
// Check that every function behaves correctly with this amount
// of stack, following direct calls in order to piece together chains
// of non-splitting functions.
var ch chain
ch.limit = objabi.StackLimit - callsize(ctxt)
if objabi.GOARCH == "arm64" {
// need extra 8 bytes below SP to save FP
ch.limit -= 8
}
// Check every function, but do the nosplit functions in a first pass,
// to make the printed failure chains as short as possible.
for _, s := range ctxt.Textp2 {
if ldr.IsNoSplit(s) {
ch.sym = s
sc.check(&ch, 0)
}
}
for _, s := range ctxt.Textp2 {
if !ldr.IsNoSplit(s) {
ch.sym = s
sc.check(&ch, 0)
}
}
}
func (sc *stkChk) check(up *chain, depth int) int {
limit := up.limit
s := up.sym
ldr := sc.ldr
ctxt := sc.ctxt
// Don't duplicate work: only need to consider each
// function at top of safe zone once.
top := limit == objabi.StackLimit-callsize(ctxt)
if top {
if sc.done.Has(s) {
return 0
}
sc.done.Set(s)
}
if depth > 500 {
sc.ctxt.Errorf(s, "nosplit stack check too deep")
sc.broke(up, 0)
return -1
}
if ldr.AttrExternal(s) {
// external function.
// should never be called directly.
// onlyctxt.Diagnose the direct caller.
// TODO(mwhudson): actually think about this.
// TODO(khr): disabled for now. Calls to external functions can only happen on the g0 stack.
// See the trampolines in src/runtime/sys_darwin_$ARCH.go.
//if depth == 1 && ldr.SymType(s) != sym.SXREF && !ctxt.DynlinkingGo() &&
// ctxt.BuildMode != BuildModeCArchive && ctxt.BuildMode != BuildModePIE && ctxt.BuildMode != BuildModeCShared && ctxt.BuildMode != BuildModePlugin {
// Errorf(s, "call to external function")
//}
return -1
}
info := ldr.FuncInfo(s)
if !info.Valid() { // external function. see above.
return -1
}
if limit < 0 {
sc.broke(up, limit)
return -1
}
// morestack looks like it calls functions,
// but it switches the stack pointer first.
if s == sc.morestack {
return 0
}
var ch chain
ch.up = up
if !ldr.IsNoSplit(s) {
// Ensure we have enough stack to call morestack.
ch.limit = limit - callsize(ctxt)
ch.sym = sc.morestack
if sc.check(&ch, depth+1) < 0 {
return -1
}
if !top {
return 0
}
// Raise limit to allow frame.
locals := info.Locals()
limit = objabi.StackLimit + int(locals) + int(ctxt.FixedFrameSize())
}
// Walk through sp adjustments in function, consuming relocs.
relocs := ldr.Relocs(s)
var ch1 chain
pcsp := obj.NewPCIter(uint32(ctxt.Arch.MinLC))
ri := 0
for pcsp.Init(info.Pcsp()); !pcsp.Done; pcsp.Next() {
// pcsp.value is in effect for [pcsp.pc, pcsp.nextpc).
// Check stack size in effect for this span.
if int32(limit)-pcsp.Value < 0 {
sc.broke(up, int(int32(limit)-pcsp.Value))
return -1
}
// Process calls in this span.
for ; ri < relocs.Count(); ri++ {
r := relocs.At2(ri)
if uint32(r.Off()) >= pcsp.NextPC {
break
}
t := r.Type()
switch {
case t.IsDirectCall():
ch.limit = int(int32(limit) - pcsp.Value - int32(callsize(ctxt)))
ch.sym = r.Sym()
if sc.check(&ch, depth+1) < 0 {
return -1
}
// Indirect call. Assume it is a call to a splitting function,
// so we have to make sure it can call morestack.
// Arrange the data structures to report both calls, so that
// if there is an error, stkprint shows all the steps involved.
case t == objabi.R_CALLIND:
ch.limit = int(int32(limit) - pcsp.Value - int32(callsize(ctxt)))
ch.sym = 0
ch1.limit = ch.limit - callsize(ctxt) // for morestack in called prologue
ch1.up = &ch
ch1.sym = sc.morestack
if sc.check(&ch1, depth+2) < 0 {
return -1
}
}
}
}
return 0
}
func (sc *stkChk) broke(ch *chain, limit int) {
sc.ctxt.Errorf(ch.sym, "nosplit stack overflow")
sc.print(ch, limit)
}
func (sc *stkChk) print(ch *chain, limit int) {
ldr := sc.ldr
ctxt := sc.ctxt
var name string
if ch.sym != 0 {
name = ldr.SymName(ch.sym)
if ldr.IsNoSplit(ch.sym) {
name += " (nosplit)"
}
} else {
name = "function pointer"
}
if ch.up == nil {
// top of chain. ch.sym != 0.
if ldr.IsNoSplit(ch.sym) {
fmt.Printf("\t%d\tassumed on entry to %s\n", ch.limit, name)
} else {
fmt.Printf("\t%d\tguaranteed after split check in %s\n", ch.limit, name)
}
} else {
sc.print(ch.up, ch.limit+callsize(ctxt))
if !haslinkregister(ctxt) {
fmt.Printf("\t%d\ton entry to %s\n", ch.limit, name)
}
}
if ch.limit != limit {
fmt.Printf("\t%d\tafter %s uses %d\n", limit, name, ch.limit-limit)
}
}
func usage() {
fmt.Fprintf(os.Stderr, "usage: link [options] main.o\n")
objabi.Flagprint(os.Stderr)
Exit(2)
}
type SymbolType int8
const (
// see also https://9p.io/magic/man2html/1/nm
TextSym SymbolType = 'T'
DataSym SymbolType = 'D'
BSSSym SymbolType = 'B'
UndefinedSym SymbolType = 'U'
TLSSym SymbolType = 't'
FrameSym SymbolType = 'm'
ParamSym SymbolType = 'p'
AutoSym SymbolType = 'a'
// Deleted auto (not a real sym, just placeholder for type)
DeletedAutoSym = 'x'
)
func genasmsym(ctxt *Link, put func(*Link, *sym.Symbol, string, SymbolType, int64)) {
// These symbols won't show up in the first loop below because we
// skip sym.STEXT symbols. Normal sym.STEXT symbols are emitted by walking textp.
s := ctxt.Syms.Lookup("runtime.text", 0)
if s.Type == sym.STEXT {
// We've already included this symbol in ctxt.Textp
// if ctxt.DynlinkingGo() && ctxt.HeadType == objabi.Hdarwin or
// on AIX with external linker.
// See data.go:/textaddress
if !(ctxt.DynlinkingGo() && ctxt.HeadType == objabi.Hdarwin) && !(ctxt.HeadType == objabi.Haix && ctxt.LinkMode == LinkExternal) {
put(ctxt, s, s.Name, TextSym, s.Value)
}
}
n := 0
// Generate base addresses for all text sections if there are multiple
for _, sect := range Segtext.Sections {
if n == 0 {
n++
continue
}
if sect.Name != ".text" || (ctxt.HeadType == objabi.Haix && ctxt.LinkMode == LinkExternal) {
// On AIX, runtime.text.X are symbols already in the symtab.
break
}
s = ctxt.Syms.ROLookup(fmt.Sprintf("runtime.text.%d", n), 0)
if s == nil {
break
}
if s.Type == sym.STEXT {
put(ctxt, s, s.Name, TextSym, s.Value)
}
n++
}
s = ctxt.Syms.Lookup("runtime.etext", 0)
if s.Type == sym.STEXT {
// We've already included this symbol in ctxt.Textp
// if ctxt.DynlinkingGo() && ctxt.HeadType == objabi.Hdarwin or
// on AIX with external linker.
// See data.go:/textaddress
if !(ctxt.DynlinkingGo() && ctxt.HeadType == objabi.Hdarwin) && !(ctxt.HeadType == objabi.Haix && ctxt.LinkMode == LinkExternal) {
put(ctxt, s, s.Name, TextSym, s.Value)
}
}
shouldBeInSymbolTable := func(s *sym.Symbol) bool {
if s.Attr.NotInSymbolTable() {
return false
}
if ctxt.HeadType == objabi.Haix && s.Name == ".go.buildinfo" {
// On AIX, .go.buildinfo must be in the symbol table as
// it has relocations.
return true
}
if (s.Name == "" || s.Name[0] == '.') && !s.IsFileLocal() && s.Name != ".rathole" && s.Name != ".TOC." {
return false
}
return true
}
for _, s := range ctxt.loader.Syms {
if s == nil {
continue
}
if !shouldBeInSymbolTable(s) {
continue
}
switch s.Type {
case sym.SCONST,
sym.SRODATA,
sym.SSYMTAB,
sym.SPCLNTAB,
sym.SINITARR,
sym.SDATA,
sym.SNOPTRDATA,
sym.SELFROSECT,
sym.SMACHOGOT,
sym.STYPE,
sym.SSTRING,
sym.SGOSTRING,
sym.SGOFUNC,
sym.SGCBITS,
sym.STYPERELRO,
sym.SSTRINGRELRO,
sym.SGOSTRINGRELRO,
sym.SGOFUNCRELRO,
sym.SGCBITSRELRO,
sym.SRODATARELRO,
sym.STYPELINK,
sym.SITABLINK,
sym.SWINDOWS:
if !s.Attr.Reachable() {
continue
}
put(ctxt, s, s.Name, DataSym, Symaddr(s))
case sym.SBSS, sym.SNOPTRBSS, sym.SLIBFUZZER_EXTRA_COUNTER:
if !s.Attr.Reachable() {
continue
}
if len(s.P) > 0 {
Errorf(s, "should not be bss (size=%d type=%v special=%v)", len(s.P), s.Type, s.Attr.Special())
}
put(ctxt, s, s.Name, BSSSym, Symaddr(s))
case sym.SUNDEFEXT:
if ctxt.HeadType == objabi.Hwindows || ctxt.HeadType == objabi.Haix || ctxt.IsELF {
put(ctxt, s, s.Name, UndefinedSym, s.Value)
}
case sym.SHOSTOBJ:
if !s.Attr.Reachable() {
continue
}
if ctxt.HeadType == objabi.Hwindows || ctxt.IsELF {
put(ctxt, s, s.Name, UndefinedSym, s.Value)
}
case sym.SDYNIMPORT:
if !s.Attr.Reachable() {
continue
}
put(ctxt, s, s.Extname(), UndefinedSym, 0)
case sym.STLSBSS:
if ctxt.LinkMode == LinkExternal {
put(ctxt, s, s.Name, TLSSym, Symaddr(s))
}
}
}
for _, s := range ctxt.Textp {
put(ctxt, s, s.Name, TextSym, s.Value)
}
if ctxt.Debugvlog != 0 || *flagN {
ctxt.Logf("symsize = %d\n", uint32(Symsize))
}
}
func Symaddr(s *sym.Symbol) int64 {
if !s.Attr.Reachable() {
Errorf(s, "unreachable symbol in symaddr")
}
return s.Value
}
func (ctxt *Link) xdefine(p string, t sym.SymKind, v int64) {
s := ctxt.Syms.Lookup(p, 0)
s.Type = t
s.Value = v
s.Attr |= sym.AttrReachable
s.Attr |= sym.AttrSpecial
s.Attr |= sym.AttrLocal
}
func (ctxt *Link) xdefine2(p string, t sym.SymKind, v int64) {
ldr := ctxt.loader
s := ldr.CreateSymForUpdate(p, 0)
s.SetType(t)
s.SetValue(v)
s.SetReachable(true)
s.SetSpecial(true)
s.SetLocal(true)
}
func datoff(s *sym.Symbol, addr int64) int64 {
if uint64(addr) >= Segdata.Vaddr {
return int64(uint64(addr) - Segdata.Vaddr + Segdata.Fileoff)
}
if uint64(addr) >= Segtext.Vaddr {
return int64(uint64(addr) - Segtext.Vaddr + Segtext.Fileoff)
}
Errorf(s, "invalid datoff %#x", addr)
return 0
}
func Entryvalue(ctxt *Link) int64 {
a := *flagEntrySymbol
if a[0] >= '0' && a[0] <= '9' {
return atolwhex(a)
}
s := ctxt.Syms.Lookup(a, 0)
if s.Type == 0 {
return *FlagTextAddr
}
if ctxt.HeadType != objabi.Haix && s.Type != sym.STEXT {
Errorf(s, "entry not text")
}
return s.Value
}
func undefsym(ctxt *Link, s *sym.Symbol) {
var r *sym.Reloc
for i := 0; i < len(s.R); i++ {
r = &s.R[i]
if r.Sym == nil { // happens for some external ARM relocs
continue
}
// TODO(mwhudson): the test of VisibilityHidden here probably doesn't make
// sense and should be removed when someone has thought about it properly.
if (r.Sym.Type == sym.Sxxx || r.Sym.Type == sym.SXREF) && !r.Sym.Attr.VisibilityHidden() {
Errorf(s, "undefined: %q", r.Sym.Name)
}
if !r.Sym.Attr.Reachable() && r.Type != objabi.R_WEAKADDROFF {
Errorf(s, "relocation target %q", r.Sym.Name)
}
}
}
func (ctxt *Link) undef() {
// undefsym performs checks (almost) identical to checks
// that report undefined relocations in relocsym.
// Both undefsym and relocsym can report same symbol as undefined,
// which results in error message duplication (see #10978).
//
// The undef is run after Arch.Asmb and could detect some
// programming errors there, but if object being linked is already
// failed with errors, it is better to avoid duplicated errors.
if nerrors > 0 {
return
}
for _, s := range ctxt.Textp {
undefsym(ctxt, s)
}
for _, s := range ctxt.datap {
undefsym(ctxt, s)
}
if nerrors > 0 {
errorexit()
}
}
func (ctxt *Link) callgraph() {
if !*FlagC {
return
}
ldr := ctxt.loader
for _, s := range ctxt.Textp2 {
relocs := ldr.Relocs(s)
for i := 0; i < relocs.Count(); i++ {
r := relocs.At2(i)
rs := r.Sym()
if rs == 0 {
continue
}
if r.Type().IsDirectCall() && (ldr.SymType(rs) == sym.STEXT || ldr.SymType(rs) == sym.SABIALIAS) {
ctxt.Logf("%s calls %s\n", ldr.SymName(s), ldr.SymName(rs))
}
}
}
}
func Rnd(v int64, r int64) int64 {
if r <= 0 {
return v
}
v += r - 1
c := v % r
if c < 0 {
c += r
}
v -= c
return v
}
func bgetc(r *bio.Reader) int {
c, err := r.ReadByte()
if err != nil {
if err != io.EOF {
log.Fatalf("reading input: %v", err)
}
return -1
}
return int(c)
}
type markKind uint8 // for postorder traversal
const (
_ markKind = iota
visiting
visited
)
func postorder(libs []*sym.Library) []*sym.Library {
order := make([]*sym.Library, 0, len(libs)) // hold the result
mark := make(map[*sym.Library]markKind, len(libs))
for _, lib := range libs {
dfs(lib, mark, &order)
}
return order
}
func dfs(lib *sym.Library, mark map[*sym.Library]markKind, order *[]*sym.Library) {
if mark[lib] == visited {
return
}
if mark[lib] == visiting {
panic("found import cycle while visiting " + lib.Pkg)
}
mark[lib] = visiting
for _, i := range lib.Imports {
dfs(i, mark, order)
}
mark[lib] = visited
*order = append(*order, lib)
}
// addToTextp populates the context Textp slice.
func addToTextp(ctxt *Link) {
// Set up ctxt.Textp, based on ctxt.Textp2.
textp := make([]*sym.Symbol, 0, len(ctxt.Textp2))
haveshlibs := len(ctxt.Shlibs) > 0
for _, tsym := range ctxt.Textp2 {
sp := ctxt.loader.Syms[tsym]
if sp == nil || !ctxt.loader.AttrReachable(tsym) {
panic("should never happen")
}
if haveshlibs && sp.Type == sym.SDYNIMPORT {
continue
}
textp = append(textp, sp)
}
ctxt.Textp = textp
}
func (ctxt *Link) loadlibfull(symGroupType []sym.SymKind, needReloc bool) {
// Load full symbol contents, resolve indexed references.
ctxt.loader.LoadFull(ctxt.Arch, ctxt.Syms, needReloc)
// Convert ctxt.Moduledata2 to ctxt.Moduledata, etc
if ctxt.Moduledata2 != 0 {
ctxt.Moduledata = ctxt.loader.Syms[ctxt.Moduledata2]
ctxt.Tlsg = ctxt.loader.Syms[ctxt.Tlsg2]
}
// Pull the symbols out.
ctxt.loader.ExtractSymbols(ctxt.Syms)
ctxt.lookup = ctxt.Syms.ROLookup
// Recreate dynexp using *sym.Symbol instead of loader.Sym
genSymsForDynexp(ctxt)
// Drop the cgodata reference.
ctxt.cgodata = nil
addToTextp(ctxt)
// Set special global symbols.
ctxt.setArchSyms(AfterLoadlibFull)
// Populate dwarfp from dwarfp2. If we see a symbol index
// whose loader.Syms entry is nil, something went wrong.
for _, si := range dwarfp2 {
syms := make([]*sym.Symbol, 0, len(si.syms))
for _, symIdx := range si.syms {
s := ctxt.loader.Syms[symIdx]
if s == nil {
panic(fmt.Sprintf("nil sym for dwarfp2 element %d", symIdx))
}
s.Attr |= sym.AttrLocal
syms = append(syms, s)
}
dwarfp = append(dwarfp, dwarfSecInfo2{syms: syms})
}
// Populate datap from datap2
ctxt.datap = make([]*sym.Symbol, len(ctxt.datap2))
for i, symIdx := range ctxt.datap2 {
s := ctxt.loader.Syms[symIdx]
if s == nil {
panic(fmt.Sprintf("nil sym for datap2 element %d", symIdx))
}
ctxt.datap[i] = s
}
// Populate the sym.Section 'Sym' fields based on their 'Sym2'
// fields.
allSegments := []*sym.Segment{&Segtext, &Segrodata, &Segrelrodata, &Segdata, &Segdwarf}
for _, seg := range allSegments {
for _, sect := range seg.Sections {
if sect.Sym2 != 0 {
s := ctxt.loader.Syms[sect.Sym2]
if s == nil {
panic(fmt.Sprintf("nil sym for sect %s sym %d", sect.Name, sect.Sym2))
}
sect.Sym = s
}
}
}
// For now, overwrite symbol type with its "group" type, as dodata
// expected. Once we converted dodata, this will probably not be
// needed.
for i, t := range symGroupType {
if t != sym.Sxxx {
s := ctxt.loader.Syms[i]
if s == nil {
continue // in dwarfcompress we drop compressed DWARF symbols
}
s.Type = t
}
}
symGroupType = nil
if ctxt.Debugvlog > 1 {
// loadlibfull is likely a good place to dump.
// Only dump under -v=2 and above.
ctxt.dumpsyms()
}
}
func symPkg(ctxt *Link, s *sym.Symbol) string {
if s == nil {
return ""
}
return ctxt.loader.SymPkg(loader.Sym(s.SymIdx))
}
func ElfSymForReloc(ctxt *Link, s *sym.Symbol) int32 {
// If putelfsym created a local version of this symbol, use that in all
// relocations.
les := ctxt.loader.SymLocalElfSym(loader.Sym(s.SymIdx))
if les != 0 {
return les
} else {
return ctxt.loader.SymElfSym(loader.Sym(s.SymIdx))
}
}
func symSub(ctxt *Link, s *sym.Symbol) *sym.Symbol {
if lsub := ctxt.loader.SubSym(loader.Sym(s.SymIdx)); lsub != 0 {
return ctxt.loader.Syms[lsub]
}
return nil
}
func (ctxt *Link) dumpsyms() {
for _, s := range ctxt.loader.Syms {
if s == nil {
continue
}
fmt.Printf("%s %s reachable=%v onlist=%v outer=%v sub=%v\n", s, s.Type, s.Attr.Reachable(), s.Attr.OnList(), s.Outer, symSub(ctxt, s))
for i := range s.R {
fmt.Println("\t", s.R[i].Type, s.R[i].Sym)
}
}
}
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