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panic("lookup failed for clone of non-external symbol")
}
l.symsByName[sver][sname] = ns
}
// Copy over selected attributes / properties. This is
// probably overkill for most of these attributes, but it's
// simpler just to copy everything.
l.copyAttributes(symIdx, ns)
if l.SymExtname(symIdx) != "" {
l.SetSymExtname(ns, l.SymExtname(symIdx))
}
if l.SymDynimplib(symIdx) != "" {
l.SetSymDynimplib(ns, l.SymDynimplib(symIdx))
}
if l.SymDynimpvers(symIdx) != "" {
l.SetSymDynimpvers(ns, l.SymDynimpvers(symIdx))
}
// Add an overwrite entry (in case there are relocations against
// the old symbol).
l.overwrite[symIdx] = ns
return ns
}
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// copyAttributes copies over all of the attributes of symbol 'src' to
// symbol 'dst'. The assumption is that 'dst' is an external symbol.
func (l *Loader) copyAttributes(src Sym, dst Sym) {
l.SetAttrReachable(dst, l.AttrReachable(src))
l.SetAttrOnList(dst, l.AttrOnList(src))
l.SetAttrLocal(dst, l.AttrLocal(src))
l.SetAttrVisibilityHidden(dst, l.AttrVisibilityHidden(src))
l.SetAttrDuplicateOK(dst, l.AttrDuplicateOK(src))
l.SetAttrShared(dst, l.AttrShared(src))
l.SetAttrExternal(dst, l.AttrExternal(src))
l.SetAttrTopFrame(dst, l.AttrTopFrame(src))
l.SetAttrSpecial(dst, l.AttrSpecial(src))
l.SetAttrCgoExportDynamic(dst, l.AttrCgoExportDynamic(src))
l.SetAttrCgoExportStatic(dst, l.AttrCgoExportStatic(src))
}
// migrateAttributes copies over all of the attributes of symbol 'src' to
// sym.Symbol 'dst'.
func (l *Loader) migrateAttributes(src Sym, dst *sym.Symbol) {
src = l.getOverwrite(src)
dst.Attr.Set(sym.AttrReachable, l.AttrReachable(src))
dst.Attr.Set(sym.AttrOnList, l.AttrOnList(src))
dst.Attr.Set(sym.AttrLocal, l.AttrLocal(src))
dst.Attr.Set(sym.AttrVisibilityHidden, l.AttrVisibilityHidden(src))
dst.Attr.Set(sym.AttrDuplicateOK, l.AttrDuplicateOK(src))
dst.Attr.Set(sym.AttrShared, l.AttrShared(src))
dst.Attr.Set(sym.AttrExternal, l.AttrExternal(src))
dst.Attr.Set(sym.AttrTopFrame, l.AttrTopFrame(src))
dst.Attr.Set(sym.AttrSpecial, l.AttrSpecial(src))
dst.Attr.Set(sym.AttrCgoExportDynamic, l.AttrCgoExportDynamic(src))
dst.Attr.Set(sym.AttrCgoExportStatic, l.AttrCgoExportStatic(src))
// Convert outer/sub relationships
if outer, ok := l.outer[src]; ok {
dst.Outer = l.Syms[outer]
}
if sub, ok := l.sub[src]; ok {
dst.Sub = l.Syms[sub]
}
// Set sub-symbol attribute. FIXME: would be better to do away
// with this and just use l.OuterSymbol() != 0 elsewhere within
// the linker.
dst.Attr.Set(sym.AttrSubSymbol, dst.Outer != nil)
// Copy over dynimplib, dynimpvers, extname.
if l.SymExtname(src) != "" {
dst.SetExtname(l.SymExtname(src))
}
if l.SymDynimplib(src) != "" {
dst.SetDynimplib(l.SymDynimplib(src))
}
if l.SymDynimpvers(src) != "" {
dst.SetDynimpvers(l.SymDynimpvers(src))
}
// Copy ELF type if set.
if et, ok := l.elfType[src]; ok {
dst.SetElfType(et)
}
}
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// CreateExtSym creates a new external symbol with the specified name
// without adding it to any lookup tables, returning a Sym index for it.
func (l *Loader) CreateExtSym(name string) Sym {
// Assign a new unique negative version -- this is to mark the
// symbol so that it can be skipped when ExtractSymbols is adding
// ext syms to the sym.Symbols hash.
l.anonVersion--
return l.newExtSym(name, l.anonVersion)
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}
// Create creates a symbol with the specified name, returning a
// sym.Symbol object for it. This method is intended for static/hidden
// symbols discovered while loading host objects. We can see more than
// one instance of a given static symbol with the same name/version,
// so we can't add them to the lookup tables "as is". Instead assign
// them fictitious (unique) versions, starting at -1 and decreasing by
// one for each newly created symbol, and record them in the
// extStaticSyms hash.
func (l *Loader) Create(name string) *sym.Symbol {
i := l.max + 1
l.max++
if l.extStart == 0 {
l.extStart = i
}
// Assign a new unique negative version -- this is to mark the
// symbol so that it can be skipped when ExtractSymbols is adding
// ext syms to the sym.Symbols hash.
l.anonVersion--
ver := l.anonVersion
l.growSyms(int(i))
s := l.allocSym(name, ver)
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l.installSym(i, s)
l.extStaticSyms[nameVer{name, ver}] = i
return s
}
func loadObjFull(l *Loader, r *oReader) {
lib := r.unit.Lib
istart := l.startIndex(r)
resolveSymRef := func(s goobj2.SymRef) *sym.Symbol {
i := l.resolve(r, s)
return l.Syms[i]
}
funcs := []funcInfoSym{}
fdsyms := []*sym.Symbol{}
var funcAllocCounts funcAllocInfo
pcdataBase := r.PcdataBase()
rslice := []Reloc{}
for i, n := 0, r.NSym()+r.NNonpkgdef(); i < n; i++ {
osym := goobj2.Sym{}
osym.Read(r.Reader, r.SymOff(i))
name := strings.Replace(osym.Name, "\"\".", r.pkgprefix, -1)
if name == "" {
continue
}
ver := abiToVer(osym.ABI, r.version)
dupok := osym.Dupok()
if dupok {
if dupsym := l.symsByName[ver][name]; dupsym != istart+Sym(i) {
if l.attrReachable.has(dupsym) {
// A dupok symbol is resolved to another package. We still need
// to record its presence in the current package, as the trampoline
// pass expects packages are laid out in dependency order.
s := l.Syms[dupsym]
if s.Type == sym.STEXT {
lib.DupTextSyms = append(lib.DupTextSyms, s)
lib.DupTextSyms2 = append(lib.DupTextSyms2, sym.LoaderSym(dupsym))
}
continue
}
}
s := l.Syms[istart+Sym(i)]
if s == nil {
continue
}
if s.Name != name { // Sanity check. We can remove it in the final version.
fmt.Println("name mismatch:", lib, i, s.Name, name)
panic("name mismatch")
}
local := osym.Local()
makeTypelink := osym.Typelink()
size := osym.Siz
// Symbol data
s.P = r.Data(i)
s.Attr.Set(sym.AttrReadOnly, r.ReadOnly())
// Relocs
relocs := l.relocs(r, i)
rslice = relocs.ReadAll(rslice)
batch := l.relocBatch
s.R = batch[:relocs.Count:relocs.Count]
l.relocBatch = batch[relocs.Count:]
l.convertRelocations(rslice, s)
// Aux symbol info
isym := -1
naux := r.NAux(i)
for j := 0; j < naux; j++ {
a := goobj2.Aux{}
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a.Read(r.Reader, r.AuxOff(i, j))
switch a.Type {
case goobj2.AuxGotype:
typ := resolveSymRef(a.Sym)
if typ != nil {
s.Gotype = typ
}
case goobj2.AuxFuncdata:
fdsyms = append(fdsyms, resolveSymRef(a.Sym))
case goobj2.AuxFuncInfo:
if a.Sym.PkgIdx != goobj2.PkgIdxSelf {
panic("funcinfo symbol not defined in current package")
}
isym = int(a.Sym.SymIdx)
case goobj2.AuxDwarfInfo, goobj2.AuxDwarfLoc, goobj2.AuxDwarfRanges, goobj2.AuxDwarfLines:
// ignored for now
default:
panic("unknown aux type")
}
}
s.File = r.pkgprefix[:len(r.pkgprefix)-1]
if dupok {
s.Attr |= sym.AttrDuplicateOK
}
if s.Size < int64(size) {
s.Size = int64(size)
}
s.Attr.Set(sym.AttrLocal, local)
s.Attr.Set(sym.AttrMakeTypelink, makeTypelink)
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if s.Type == sym.SDWARFINFO {
// For DWARF symbols, replace `"".` to actual package prefix
// in the symbol content.
// TODO: maybe we should do this in the compiler and get rid
// of this.
patchDWARFName(s, r)
}
if s.Type != sym.STEXT {
continue
}
if isym == -1 {
continue
}
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// Record function sym and associated info for additional
// processing in the loop below.
fwis := funcInfoSym{s: s, isym: isym, osym: osym}
funcs = append(funcs, fwis)
// Read the goobj2.FuncInfo for this text symbol so that we can
// collect allocation counts. We'll read it again in the loop
// below.
b := r.Data(isym)
info := goobj2.FuncInfo{}
info.Read(b)
funcAllocCounts.symPtr += uint32(len(info.File))
funcAllocCounts.pcData += uint32(len(info.Pcdata))
funcAllocCounts.inlCall += uint32(len(info.InlTree))
funcAllocCounts.fdOff += uint32(len(info.Funcdataoff))
}
// At this point we can do batch allocation of the sym.FuncInfo's,
// along with the slices of sub-objects they use.
fiBatch := make([]sym.FuncInfo, len(funcs))
inlCallBatch := make([]sym.InlinedCall, funcAllocCounts.inlCall)
symPtrBatch := make([]*sym.Symbol, funcAllocCounts.symPtr)
pcDataBatch := make([]sym.Pcdata, funcAllocCounts.pcData)
fdOffBatch := make([]int64, funcAllocCounts.fdOff)
// Populate FuncInfo contents for func symbols.
for fi := 0; fi < len(funcs); fi++ {
s := funcs[fi].s
isym := funcs[fi].isym
osym := funcs[fi].osym
s.FuncInfo = &fiBatch[0]
fiBatch = fiBatch[1:]
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b := r.Data(isym)
info := goobj2.FuncInfo{}
info.Read(b)
if info.NoSplit != 0 {
s.Attr |= sym.AttrNoSplit
}
if osym.ReflectMethod() {
s.Attr |= sym.AttrReflectMethod
}
if r.Flags()&goobj2.ObjFlagShared != 0 {
s.Attr |= sym.AttrShared
}
if osym.TopFrame() {
s.Attr |= sym.AttrTopFrame
}
pc := s.FuncInfo
if len(info.Funcdataoff) != 0 {
nfd := len(info.Funcdataoff)
pc.Funcdata = fdsyms[:nfd:nfd]
fdsyms = fdsyms[nfd:]
info.Pcdata = append(info.Pcdata, info.PcdataEnd) // for the ease of knowing where it ends
pc.Args = int32(info.Args)
pc.Locals = int32(info.Locals)
npc := len(info.Pcdata) - 1 // -1 as we appended one above
pc.Pcdata = pcDataBatch[:npc:npc]
pcDataBatch = pcDataBatch[npc:]
nfd := len(info.Funcdataoff)
pc.Funcdataoff = fdOffBatch[:nfd:nfd]
fdOffBatch = fdOffBatch[nfd:]
nsp := len(info.File)
pc.File = symPtrBatch[:nsp:nsp]
symPtrBatch = symPtrBatch[nsp:]
nic := len(info.InlTree)
pc.InlTree = inlCallBatch[:nic:nic]
inlCallBatch = inlCallBatch[nic:]
pc.Pcsp.P = r.BytesAt(pcdataBase+info.Pcsp, int(info.Pcfile-info.Pcsp))
pc.Pcfile.P = r.BytesAt(pcdataBase+info.Pcfile, int(info.Pcline-info.Pcfile))
pc.Pcline.P = r.BytesAt(pcdataBase+info.Pcline, int(info.Pcinline-info.Pcline))
pc.Pcinline.P = r.BytesAt(pcdataBase+info.Pcinline, int(info.Pcdata[0]-info.Pcinline))
for k := range pc.Pcdata {
pc.Pcdata[k].P = r.BytesAt(pcdataBase+info.Pcdata[k], int(info.Pcdata[k+1]-info.Pcdata[k]))
}
for k := range pc.Funcdataoff {
pc.Funcdataoff[k] = int64(info.Funcdataoff[k])
}
for k := range pc.File {
pc.File[k] = resolveSymRef(info.File[k])
}
for k := range pc.InlTree {
inl := &info.InlTree[k]
pc.InlTree[k] = sym.InlinedCall{
Parent: inl.Parent,
File: resolveSymRef(inl.File),
Line: inl.Line,
Func: l.SymName(l.resolve(r, inl.Func)),
ParentPC: inl.ParentPC,
}
}
dupok := osym.Dupok()
if !dupok {
if s.Attr.OnList() {
log.Fatalf("symbol %s listed multiple times", s.Name)
}
s.Attr.Set(sym.AttrOnList, true)
lib.Textp = append(lib.Textp, s)
lib.Textp2 = append(lib.Textp2, sym.LoaderSym(isym))
} else {
// there may be a dup in another package
// put into a temp list and add to text later
lib.DupTextSyms = append(lib.DupTextSyms, s)
lib.DupTextSyms2 = append(lib.DupTextSyms2, sym.LoaderSym(isym))
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// convertRelocations takes a vector of loader.Reloc relocations and
// translates them into an equivalent set of sym.Reloc relocations on
// the symbol "dst", performing fixups along the way for ABI aliases,
// etc. It is assumed that the called has pre-allocated the dst symbol
// relocations slice.
func (l *Loader) convertRelocations(src []Reloc, dst *sym.Symbol) {
for j := range dst.R {
r := src[j]
rs := r.Sym
sz := r.Size
rt := r.Type
if rt == objabi.R_METHODOFF {
if l.attrReachable.has(rs) {
rt = objabi.R_ADDROFF
} else {
sz = 0
rs = 0
}
}
if rt == objabi.R_WEAKADDROFF && !l.attrReachable.has(rs) {
rs = 0
sz = 0
}
if rs != 0 && l.Syms[rs] != nil && l.Syms[rs].Type == sym.SABIALIAS {
rsrelocs := l.Relocs(rs)
rs = rsrelocs.At(0).Sym
}
dst.R[j] = sym.Reloc{
Off: r.Off,
Siz: sz,
Type: rt,
Add: r.Add,
Sym: l.Syms[rs],
}
}
}
var emptyPkg = []byte(`"".`)
func patchDWARFName1(p []byte, r *oReader) ([]byte, int) {
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// This is kind of ugly. Really the package name should not
// even be included here.
if len(p) < 1 || p[0] != dwarf.DW_ABRV_FUNCTION {
return p, -1
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}
e := bytes.IndexByte(p, 0)
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if e == -1 {
return p, -1
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}
if !bytes.Contains(p[:e], emptyPkg) {
return p, -1
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}
pkgprefix := []byte(r.pkgprefix)
patched := bytes.Replace(p[:e], emptyPkg, pkgprefix, -1)
return append(patched, p[e:]...), e
}
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func patchDWARFName(s *sym.Symbol, r *oReader) {
patched, e := patchDWARFName1(s.P, r)
if e == -1 {
return
}
s.P = patched
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s.Attr.Set(sym.AttrReadOnly, false)
delta := int64(len(s.P)) - s.Size
s.Size = int64(len(s.P))
for i := range s.R {
r := &s.R[i]
if r.Off > int32(e) {
r.Off += int32(delta)
}
}
}
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// UndefinedRelocTargets iterates through the global symbol index
// space, looking for symbols with relocations targeting undefined
// references. The linker's loadlib method uses this to determine if
// there are unresolved references to functions in system libraries
// (for example, libgcc.a), presumably due to CGO code. Return
// value is a list of loader.Sym's corresponding to the undefined
// cross-refs. The "limit" param controls the maximum number of
// results returned; if "limit" is -1, then all undefs are returned.
func (l *Loader) UndefinedRelocTargets(limit int) []Sym {
result := []Sym{}
rslice := []Reloc{}
for si := Sym(1); si <= l.max; si++ {
if _, ok := l.overwrite[si]; ok {
continue
}
relocs := l.Relocs(si)
rslice = relocs.ReadAll(rslice)
for ri := 0; ri < relocs.Count; ri++ {
r := &rslice[ri]
if r.Sym != 0 && l.SymType(r.Sym) == sym.SXREF && l.RawSymName(r.Sym) != ".got" {
result = append(result, r.Sym)
if limit != -1 && len(result) >= limit {
break
}
}
}
}
return result
}
// For debugging.
func (l *Loader) Dump() {
fmt.Println("objs")
for _, obj := range l.objs {
if obj.r != nil {
fmt.Println(obj.i, obj.r.unit.Lib)
}
}
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fmt.Println("extStart:", l.extStart)
fmt.Println("max:", l.max)
fmt.Println("syms")
for i, s := range l.Syms {
if i == 0 {
continue
}
if s != nil {
fmt.Println(i, s, s.Type)
} else {
otag := ""
si := Sym(i)
if _, ok := l.overwrite[si]; ok {
si = l.getOverwrite(si)
otag = fmt.Sprintf(" <overwritten to %d>", si)
}
fmt.Println(i, l.SymName(si), "<not loaded>", otag)
}
}
fmt.Println("overwrite:", l.overwrite)
fmt.Println("symsByName")
for name, i := range l.symsByName[0] {
fmt.Println(i, name, 0)
}
for name, i := range l.symsByName[1] {
fmt.Println(i, name, 1)