1 // Copyright 2019 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
14 "cmd/link/internal/sym"
26 // Sym encapsulates a global symbol index, used to identify a specific
27 // Go symbol. The 0-valued Sym is corresponds to an invalid symbol.
30 // Relocs encapsulates the set of relocations on a given symbol; an
31 // instance of this type is returned by the Loader Relocs() method.
35 li uint32 // local index of symbol whose relocs we're examining
36 r *oReader // object reader for containing package
40 // ExtReloc contains the payload for an external relocation.
41 type ExtReloc struct {
48 // Reloc holds a "handle" to access a relocation record from an
56 func (rel Reloc) Type() objabi.RelocType { return objabi.RelocType(rel.Reloc.Type()) &^ objabi.R_WEAK }
57 func (rel Reloc) Weak() bool { return objabi.RelocType(rel.Reloc.Type())&objabi.R_WEAK != 0 }
58 func (rel Reloc) SetType(t objabi.RelocType) { rel.Reloc.SetType(uint16(t)) }
59 func (rel Reloc) Sym() Sym { return rel.l.resolve(rel.r, rel.Reloc.Sym()) }
60 func (rel Reloc) SetSym(s Sym) { rel.Reloc.SetSym(goobj.SymRef{PkgIdx: 0, SymIdx: uint32(s)}) }
61 func (rel Reloc) IsMarker() bool { return rel.Siz() == 0 }
63 // Aux holds a "handle" to access an aux symbol record from an
71 func (a Aux) Sym() Sym { return a.l.resolve(a.r, a.Aux.Sym()) }
73 // oReader is a wrapper type of obj.Reader, along with some
77 unit *sym.CompilationUnit
78 version int // version of static symbol
80 syms []Sym // Sym's global index, indexed by local index
81 pkg []uint32 // indices of referenced package by PkgIdx (index into loader.objs array)
82 ndef int // cache goobj.Reader.NSym()
83 nhashed64def int // cache goobj.Reader.NHashed64Def()
84 nhasheddef int // cache goobj.Reader.NHashedDef()
85 objidx uint32 // index of this reader in the objs slice
88 // Total number of defined symbols (package symbols, hashed symbols, and
89 // non-package symbols).
90 func (r *oReader) NAlldef() int { return r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef() }
97 // objSym represents a symbol in an object file. It is a tuple of
98 // the object and the symbol's local index.
99 // For external symbols, objidx is the index of l.extReader (extObj),
100 // s is its index into the payload array.
101 // {0, 0} represents the nil symbol.
103 objidx uint32 // index of the object (in l.objs array)
104 s uint32 // local index
107 type nameVer struct {
115 func (bm Bitmap) Set(i Sym) {
116 n, r := uint(i)/32, uint(i)%32
120 // unset the i-th bit.
121 func (bm Bitmap) Unset(i Sym) {
122 n, r := uint(i)/32, uint(i)%32
126 // whether the i-th bit is set.
127 func (bm Bitmap) Has(i Sym) bool {
128 n, r := uint(i)/32, uint(i)%32
129 return bm[n]&(1<<r) != 0
132 // return current length of bitmap in bits.
133 func (bm Bitmap) Len() int {
137 // return the number of bits set.
138 func (bm Bitmap) Count() int {
140 for _, x := range bm {
141 s += bits.OnesCount32(x)
146 func MakeBitmap(n int) Bitmap {
147 return make(Bitmap, (n+31)/32)
150 // growBitmap insures that the specified bitmap has enough capacity,
151 // reallocating (doubling the size) if needed.
152 func growBitmap(reqLen int, b Bitmap) Bitmap {
155 b = append(b, MakeBitmap(reqLen+1-curLen)...)
160 type symAndSize struct {
165 // A Loader loads new object files and resolves indexed symbol references.
167 // Notes on the layout of global symbol index space:
169 // - Go object files are read before host object files; each Go object
170 // read adds its defined package symbols to the global index space.
171 // Nonpackage symbols are not yet added.
173 // - In loader.LoadNonpkgSyms, add non-package defined symbols and
174 // references in all object files to the global index space.
176 // - Host object file loading happens; the host object loader does a
177 // name/version lookup for each symbol it finds; this can wind up
178 // extending the external symbol index space range. The host object
179 // loader stores symbol payloads in loader.payloads using SymbolBuilder.
181 // - Each symbol gets a unique global index. For duplicated and
182 // overwriting/overwritten symbols, the second (or later) appearance
183 // of the symbol gets the same global index as the first appearance.
185 start map[*oReader]Sym // map from object file to its start index
186 objs []objIdx // sorted by start index (i.e. objIdx.i)
187 extStart Sym // from this index on, the symbols are externally defined
188 builtinSyms []Sym // global index of builtin symbols
190 objSyms []objSym // global index mapping to local index
192 symsByName [2]map[string]Sym // map symbol name to index, two maps are for ABI0 and ABIInternal
193 extStaticSyms map[nameVer]Sym // externally defined static symbols, keyed by name
195 extReader *oReader // a dummy oReader, for external symbols
196 payloadBatch []extSymPayload
197 payloads []*extSymPayload // contents of linker-materialized external syms
198 values []int64 // symbol values, indexed by global sym index
200 sects []*sym.Section // sections
201 symSects []uint16 // symbol's section, index to sects array
203 align []uint8 // symbol 2^N alignment, indexed by global index
205 deferReturnTramp map[Sym]bool // whether the symbol is a trampoline of a deferreturn call
207 objByPkg map[string]uint32 // map package path to the index of its Go object reader
209 anonVersion int // most recently assigned ext static sym pseudo-version
211 // Bitmaps and other side structures used to store data used to store
212 // symbol flags/attributes; these are to be accessed via the
213 // corresponding loader "AttrXXX" and "SetAttrXXX" methods. Please
214 // visit the comments on these methods for more details on the
215 // semantics / interpretation of the specific flags or attribute.
216 attrReachable Bitmap // reachable symbols, indexed by global index
217 attrOnList Bitmap // "on list" symbols, indexed by global index
218 attrLocal Bitmap // "local" symbols, indexed by global index
219 attrNotInSymbolTable Bitmap // "not in symtab" symbols, indexed by global idx
220 attrUsedInIface Bitmap // "used in interface" symbols, indexed by global idx
221 attrVisibilityHidden Bitmap // hidden symbols, indexed by ext sym index
222 attrDuplicateOK Bitmap // dupOK symbols, indexed by ext sym index
223 attrShared Bitmap // shared symbols, indexed by ext sym index
224 attrExternal Bitmap // external symbols, indexed by ext sym index
226 attrReadOnly map[Sym]bool // readonly data for this sym
227 attrSpecial map[Sym]struct{} // "special" frame symbols
228 attrCgoExportDynamic map[Sym]struct{} // "cgo_export_dynamic" symbols
229 attrCgoExportStatic map[Sym]struct{} // "cgo_export_static" symbols
230 generatedSyms map[Sym]struct{} // symbols that generate their content
232 // Outer and Sub relations for symbols.
233 // TODO: figure out whether it's more efficient to just have these
234 // as fields on extSymPayload (note that this won't be a viable
235 // strategy if somewhere in the linker we set sub/outer for a
236 // non-external sym).
240 dynimplib map[Sym]string // stores Dynimplib symbol attribute
241 dynimpvers map[Sym]string // stores Dynimpvers symbol attribute
242 localentry map[Sym]uint8 // stores Localentry symbol attribute
243 extname map[Sym]string // stores Extname symbol attribute
244 elfType map[Sym]elf.SymType // stores elf type symbol property
245 elfSym map[Sym]int32 // stores elf sym symbol property
246 localElfSym map[Sym]int32 // stores "local" elf sym symbol property
247 symPkg map[Sym]string // stores package for symbol, or library for shlib-derived syms
248 plt map[Sym]int32 // stores dynimport for pe objects
249 got map[Sym]int32 // stores got for pe objects
250 dynid map[Sym]int32 // stores Dynid for symbol
252 relocVariant map[relocId]sym.RelocVariant // stores variant relocs
254 // Used to implement field tracking; created during deadcode if
255 // field tracking is enabled. Reachparent[K] contains the index of
256 // the symbol that triggered the marking of symbol K as live.
259 // CgoExports records cgo-exported symbols by SymName.
260 CgoExports map[string]Sym
264 strictDupMsgs int // number of strict-dup warning/errors, when FlagStrictDups is enabled
266 elfsetstring elfsetstringFunc
268 errorReporter *ErrorReporter
270 npkgsyms int // number of package symbols, for accounting
271 nhashedsyms int // number of hashed symbols, for accounting
289 type elfsetstringFunc func(str string, off int)
291 // extSymPayload holds the payload (data + relocations) for linker-synthesized
292 // external symbols (note that symbol value is stored in a separate slice).
293 type extSymPayload struct {
294 name string // TODO: would this be better as offset into str table?
298 objidx uint32 // index of original object if sym made by cloneToExternal
306 FlagStrictDups = 1 << iota
309 func NewLoader(flags uint32, elfsetstring elfsetstringFunc, reporter *ErrorReporter) *Loader {
310 nbuiltin := goobj.NBuiltin()
311 extReader := &oReader{objidx: extObj}
313 start: make(map[*oReader]Sym),
314 objs: []objIdx{{}, {extReader, 0}}, // reserve index 0 for nil symbol, 1 for external symbols
315 objSyms: make([]objSym, 1, 1), // This will get overwritten later.
316 extReader: extReader,
317 symsByName: [2]map[string]Sym{make(map[string]Sym, 80000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
318 objByPkg: make(map[string]uint32),
319 outer: make(map[Sym]Sym),
320 sub: make(map[Sym]Sym),
321 dynimplib: make(map[Sym]string),
322 dynimpvers: make(map[Sym]string),
323 localentry: make(map[Sym]uint8),
324 extname: make(map[Sym]string),
325 attrReadOnly: make(map[Sym]bool),
326 elfType: make(map[Sym]elf.SymType),
327 elfSym: make(map[Sym]int32),
328 localElfSym: make(map[Sym]int32),
329 symPkg: make(map[Sym]string),
330 plt: make(map[Sym]int32),
331 got: make(map[Sym]int32),
332 dynid: make(map[Sym]int32),
333 attrSpecial: make(map[Sym]struct{}),
334 attrCgoExportDynamic: make(map[Sym]struct{}),
335 attrCgoExportStatic: make(map[Sym]struct{}),
336 generatedSyms: make(map[Sym]struct{}),
337 deferReturnTramp: make(map[Sym]bool),
338 extStaticSyms: make(map[nameVer]Sym),
339 builtinSyms: make([]Sym, nbuiltin),
341 elfsetstring: elfsetstring,
342 errorReporter: reporter,
343 sects: []*sym.Section{nil}, // reserve index 0 for nil section
349 // Add object file r, return the start index.
350 func (l *Loader) addObj(pkg string, r *oReader) Sym {
351 if _, ok := l.start[r]; ok {
352 panic("already added")
354 pkg = objabi.PathToPrefix(pkg) // the object file contains escaped package path
355 if _, ok := l.objByPkg[pkg]; !ok {
356 l.objByPkg[pkg] = r.objidx
358 i := Sym(len(l.objSyms))
360 l.objs = append(l.objs, objIdx{r, i})
361 if r.NeedNameExpansion() && !r.FromAssembly() {
362 panic("object compiled without -p")
367 // Add a symbol from an object file, return the global index.
368 // If the symbol already exist, it returns the index of that symbol.
369 func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj.Sym) Sym {
372 panic("addSym called after external symbol is created")
374 i := Sym(len(l.objSyms))
375 addToGlobal := func() {
376 l.objSyms = append(l.objSyms, objSym{r.objidx, li})
378 if name == "" && kind != hashed64Def && kind != hashedDef {
380 return i // unnamed aux symbol
382 if ver == r.version {
383 // Static symbol. Add its global index but don't
384 // add to name lookup table, as it cannot be
385 // referenced by name.
391 // Defined package symbols cannot be dup to each other.
392 // We load all the package symbols first, so we don't need
393 // to check dup here.
394 // We still add it to the lookup table, as it may still be
395 // referenced by name (e.g. through linkname).
396 l.symsByName[ver][name] = i
399 case hashed64Def, hashedDef:
400 // Hashed (content-addressable) symbol. Check the hash
401 // but don't add to name lookup table, as they are not
402 // referenced by name. Also no need to do overwriting
403 // check, as same hash indicates same content.
404 var checkHash func() (symAndSize, bool)
405 var addToHashMap func(symAndSize)
406 var h64 uint64 // only used for hashed64Def
407 var h *goobj.HashType // only used for hashedDef
408 if kind == hashed64Def {
409 checkHash = func() (symAndSize, bool) {
410 h64 = r.Hash64(li - uint32(r.ndef))
411 s, existed := st.hashed64Syms[h64]
414 addToHashMap = func(ss symAndSize) { st.hashed64Syms[h64] = ss }
416 checkHash = func() (symAndSize, bool) {
417 h = r.Hash(li - uint32(r.ndef+r.nhashed64def))
418 s, existed := st.hashedSyms[*h]
421 addToHashMap = func(ss symAndSize) { st.hashedSyms[*h] = ss }
424 if s, existed := checkHash(); existed {
425 // The content hash is built from symbol data and relocations. In the
426 // object file, the symbol data may not always contain trailing zeros,
427 // e.g. for [5]int{1,2,3} and [100]int{1,2,3}, the data is same
428 // (although the size is different).
429 // Also, for short symbols, the content hash is the identity function of
430 // the 8 bytes, and trailing zeros doesn't change the hash value, e.g.
431 // hash("A") == hash("A\0\0\0").
432 // So when two symbols have the same hash, we need to use the one with
435 // New symbol has larger size, use the new one. Rewrite the index mapping.
436 l.objSyms[s.sym] = objSym{r.objidx, li}
437 addToHashMap(symAndSize{s.sym, siz})
441 addToHashMap(symAndSize{i, siz})
446 // Non-package (named) symbol. Check if it already exists.
447 oldi, existed := l.symsByName[ver][name]
449 l.symsByName[ver][name] = i
453 // symbol already exists
455 if l.flags&FlagStrictDups != 0 {
456 l.checkdup(name, r, li, oldi)
458 // Fix for issue #47185 -- given two dupok symbols with
459 // different sizes, favor symbol with larger size. See
460 // also issue #46653.
461 szdup := l.SymSize(oldi)
462 sz := int64(r.Sym(li).Siz())
464 // new symbol overwrites old symbol.
465 l.objSyms[oldi] = objSym{r.objidx, li}
469 oldr, oldli := l.toLocal(oldi)
470 oldsym := oldr.Sym(oldli)
474 overwrite := r.DataSize(li) != 0
476 // new symbol overwrites old symbol.
477 oldtyp := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
478 if !(oldtyp.IsData() && oldr.DataSize(oldli) == 0) {
479 log.Fatalf("duplicated definition of symbol %s, from %s and %s", name, r.unit.Lib.Pkg, oldr.unit.Lib.Pkg)
481 l.objSyms[oldi] = objSym{r.objidx, li}
483 // old symbol overwrites new symbol.
484 typ := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
485 if !typ.IsData() { // only allow overwriting data symbol
486 log.Fatalf("duplicated definition of symbol %s, from %s and %s", name, r.unit.Lib.Pkg, oldr.unit.Lib.Pkg)
492 // newExtSym creates a new external sym with the specified
494 func (l *Loader) newExtSym(name string, ver int) Sym {
495 i := Sym(len(l.objSyms))
499 l.growValues(int(i) + 1)
500 l.growAttrBitmaps(int(i) + 1)
501 pi := l.newPayload(name, ver)
502 l.objSyms = append(l.objSyms, objSym{l.extReader.objidx, uint32(pi)})
503 l.extReader.syms = append(l.extReader.syms, i)
507 // LookupOrCreateSym looks up the symbol with the specified name/version,
508 // returning its Sym index if found. If the lookup fails, a new external
509 // Sym will be created, entered into the lookup tables, and returned.
510 func (l *Loader) LookupOrCreateSym(name string, ver int) Sym {
511 i := l.Lookup(name, ver)
515 i = l.newExtSym(name, ver)
516 static := ver >= sym.SymVerStatic || ver < 0
518 l.extStaticSyms[nameVer{name, ver}] = i
520 l.symsByName[ver][name] = i
525 // AddCgoExport records a cgo-exported symbol in l.CgoExports.
526 // This table is used to identify the correct Go symbol ABI to use
527 // to resolve references from host objects (which don't have ABIs).
528 func (l *Loader) AddCgoExport(s Sym) {
529 if l.CgoExports == nil {
530 l.CgoExports = make(map[string]Sym)
532 l.CgoExports[l.SymName(s)] = s
535 // LookupOrCreateCgoExport is like LookupOrCreateSym, but if ver
536 // indicates a global symbol, it uses the CgoExport table to determine
537 // the appropriate symbol version (ABI) to use. ver must be either 0
538 // or a static symbol version.
539 func (l *Loader) LookupOrCreateCgoExport(name string, ver int) Sym {
540 if ver >= sym.SymVerStatic {
541 return l.LookupOrCreateSym(name, ver)
544 panic("ver must be 0 or a static version")
546 // Look for a cgo-exported symbol from Go.
547 if s, ok := l.CgoExports[name]; ok {
550 // Otherwise, this must just be a symbol in the host object.
551 // Create a version 0 symbol for it.
552 return l.LookupOrCreateSym(name, 0)
555 func (l *Loader) IsExternal(i Sym) bool {
557 return l.isExtReader(r)
560 func (l *Loader) isExtReader(r *oReader) bool {
561 return r == l.extReader
564 // For external symbol, return its index in the payloads array.
565 // XXX result is actually not a global index. We (ab)use the Sym type
566 // so we don't need conversion for accessing bitmaps.
567 func (l *Loader) extIndex(i Sym) Sym {
568 _, li := l.toLocal(i)
572 // Get a new payload for external symbol, return its index in
573 // the payloads array.
574 func (l *Loader) newPayload(name string, ver int) int {
575 pi := len(l.payloads)
576 pp := l.allocPayload()
579 l.payloads = append(l.payloads, pp)
580 l.growExtAttrBitmaps()
584 // getPayload returns a pointer to the extSymPayload struct for an
585 // external symbol if the symbol has a payload. Will panic if the
586 // symbol in question is bogus (zero or not an external sym).
587 func (l *Loader) getPayload(i Sym) *extSymPayload {
588 if !l.IsExternal(i) {
589 panic(fmt.Sprintf("bogus symbol index %d in getPayload", i))
592 return l.payloads[pi]
595 // allocPayload allocates a new payload.
596 func (l *Loader) allocPayload() *extSymPayload {
597 batch := l.payloadBatch
599 batch = make([]extSymPayload, 1000)
602 l.payloadBatch = batch[1:]
606 func (ms *extSymPayload) Grow(siz int64) {
607 if int64(int(siz)) != siz {
608 log.Fatalf("symgrow size %d too long", siz)
610 if int64(len(ms.data)) >= siz {
613 if cap(ms.data) < int(siz) {
615 ms.data = append(ms.data, make([]byte, int(siz)+1-cl)...)
616 ms.data = ms.data[0:cl]
618 ms.data = ms.data[:siz]
621 // Convert a local index to a global index.
622 func (l *Loader) toGlobal(r *oReader, i uint32) Sym {
626 // Convert a global index to a local index.
627 func (l *Loader) toLocal(i Sym) (*oReader, uint32) {
628 return l.objs[l.objSyms[i].objidx].r, l.objSyms[i].s
631 // Resolve a local symbol reference. Return global index.
632 func (l *Loader) resolve(r *oReader, s goobj.SymRef) Sym {
634 switch p := s.PkgIdx; p {
635 case goobj.PkgIdxInvalid:
636 // {0, X} with non-zero X is never a valid sym reference from a Go object.
637 // We steal this space for symbol references from external objects.
638 // In this case, X is just the global index.
639 if l.isExtReader(r) {
646 case goobj.PkgIdxHashed64:
647 i := int(s.SymIdx) + r.ndef
649 case goobj.PkgIdxHashed:
650 i := int(s.SymIdx) + r.ndef + r.nhashed64def
652 case goobj.PkgIdxNone:
653 i := int(s.SymIdx) + r.ndef + r.nhashed64def + r.nhasheddef
655 case goobj.PkgIdxBuiltin:
656 if bi := l.builtinSyms[s.SymIdx]; bi != 0 {
659 l.reportMissingBuiltin(int(s.SymIdx), r.unit.Lib.Pkg)
661 case goobj.PkgIdxSelf:
664 rr = l.objs[r.pkg[p]].r
666 return l.toGlobal(rr, s.SymIdx)
669 // reportMissingBuiltin issues an error in the case where we have a
670 // relocation against a runtime builtin whose definition is not found
671 // when the runtime package is built. The canonical example is
672 // "runtime.racefuncenter" -- currently if you do something like
674 // go build -gcflags=-race myprogram.go
676 // the compiler will insert calls to the builtin runtime.racefuncenter,
677 // but the version of the runtime used for linkage won't actually contain
678 // definitions of that symbol. See issue #42396 for details.
680 // As currently implemented, this is a fatal error. This has drawbacks
681 // in that if there are multiple missing builtins, the error will only
682 // cite the first one. On the plus side, terminating the link here has
683 // advantages in that we won't run the risk of panics or crashes later
684 // on in the linker due to R_CALL relocations with 0-valued target
686 func (l *Loader) reportMissingBuiltin(bsym int, reflib string) {
687 bname, _ := goobj.BuiltinName(bsym)
688 log.Fatalf("reference to undefined builtin %q from package %q",
692 // Look up a symbol by name, return global index, or 0 if not found.
693 // This is more like Syms.ROLookup than Lookup -- it doesn't create
695 func (l *Loader) Lookup(name string, ver int) Sym {
696 if ver >= sym.SymVerStatic || ver < 0 {
697 return l.extStaticSyms[nameVer{name, ver}]
699 return l.symsByName[ver][name]
702 // Check that duplicate symbols have same contents.
703 func (l *Loader) checkdup(name string, r *oReader, li uint32, dup Sym) {
705 rdup, ldup := l.toLocal(dup)
706 pdup := rdup.Data(ldup)
707 reason := "same length but different contents"
708 if len(p) != len(pdup) {
709 reason = fmt.Sprintf("new length %d != old length %d", len(p), len(pdup))
710 } else if bytes.Equal(p, pdup) {
711 // For BSS symbols, we need to check size as well, see issue 46653.
712 szdup := l.SymSize(dup)
713 sz := int64(r.Sym(li).Siz())
717 reason = fmt.Sprintf("different sizes: new size %d != old size %d",
720 fmt.Fprintf(os.Stderr, "cmd/link: while reading object for '%v': duplicate symbol '%s', previous def at '%v', with mismatched payload: %s\n", r.unit.Lib, name, rdup.unit.Lib, reason)
722 // For the moment, allow DWARF subprogram DIEs for
723 // auto-generated wrapper functions. What seems to happen
724 // here is that we get different line numbers on formal
725 // params; I am guessing that the pos is being inherited
726 // from the spot where the wrapper is needed.
727 allowed := strings.HasPrefix(name, "go.info.go.interface") ||
728 strings.HasPrefix(name, "go.info.go.builtin") ||
729 strings.HasPrefix(name, "go.debuglines")
735 func (l *Loader) NStrictDupMsgs() int { return l.strictDupMsgs }
737 // Number of total symbols.
738 func (l *Loader) NSym() int {
739 return len(l.objSyms)
742 // Number of defined Go symbols.
743 func (l *Loader) NDef() int {
744 return int(l.extStart)
747 // Number of reachable symbols.
748 func (l *Loader) NReachableSym() int {
749 return l.attrReachable.Count()
752 // Returns the raw (unpatched) name of the i-th symbol.
753 func (l *Loader) RawSymName(i Sym) string {
755 pp := l.getPayload(i)
758 r, li := l.toLocal(i)
759 return r.Sym(li).Name(r.Reader)
762 // Returns the (patched) name of the i-th symbol.
763 func (l *Loader) SymName(i Sym) string {
765 pp := l.getPayload(i)
768 r, li := l.toLocal(i)
772 name := r.Sym(li).Name(r.Reader)
773 if !r.NeedNameExpansion() {
776 return strings.Replace(name, "\"\".", r.pkgprefix, -1)
779 // Returns the version of the i-th symbol.
780 func (l *Loader) SymVersion(i Sym) int {
782 pp := l.getPayload(i)
785 r, li := l.toLocal(i)
786 return int(abiToVer(r.Sym(li).ABI(), r.version))
789 func (l *Loader) IsFileLocal(i Sym) bool {
790 return l.SymVersion(i) >= sym.SymVerStatic
793 // IsFromAssembly returns true if this symbol is derived from an
794 // object file generated by the Go assembler.
795 func (l *Loader) IsFromAssembly(i Sym) bool {
800 return r.FromAssembly()
803 // Returns the type of the i-th symbol.
804 func (l *Loader) SymType(i Sym) sym.SymKind {
806 pp := l.getPayload(i)
812 r, li := l.toLocal(i)
813 return sym.AbiSymKindToSymKind[objabi.SymKind(r.Sym(li).Type())]
816 // Returns the attributes of the i-th symbol.
817 func (l *Loader) SymAttr(i Sym) uint8 {
819 // TODO: do something? External symbols have different representation of attributes.
820 // For now, ReflectMethod, NoSplit, GoType, and Typelink are used and they cannot be
821 // set by external symbol.
824 r, li := l.toLocal(i)
825 return r.Sym(li).Flag()
828 // Returns the size of the i-th symbol.
829 func (l *Loader) SymSize(i Sym) int64 {
831 pp := l.getPayload(i)
834 r, li := l.toLocal(i)
835 return int64(r.Sym(li).Siz())
838 // AttrReachable returns true for symbols that are transitively
839 // referenced from the entry points. Unreachable symbols are not
840 // written to the output.
841 func (l *Loader) AttrReachable(i Sym) bool {
842 return l.attrReachable.Has(i)
845 // SetAttrReachable sets the reachability property for a symbol (see
847 func (l *Loader) SetAttrReachable(i Sym, v bool) {
849 l.attrReachable.Set(i)
851 l.attrReachable.Unset(i)
855 // AttrOnList returns true for symbols that are on some list (such as
856 // the list of all text symbols, or one of the lists of data symbols)
857 // and is consulted to avoid bugs where a symbol is put on a list
859 func (l *Loader) AttrOnList(i Sym) bool {
860 return l.attrOnList.Has(i)
863 // SetAttrOnList sets the "on list" property for a symbol (see
865 func (l *Loader) SetAttrOnList(i Sym, v bool) {
869 l.attrOnList.Unset(i)
873 // AttrLocal returns true for symbols that are only visible within the
874 // module (executable or shared library) being linked. This attribute
875 // is applied to thunks and certain other linker-generated symbols.
876 func (l *Loader) AttrLocal(i Sym) bool {
877 return l.attrLocal.Has(i)
880 // SetAttrLocal the "local" property for a symbol (see AttrLocal above).
881 func (l *Loader) SetAttrLocal(i Sym, v bool) {
889 // AttrUsedInIface returns true for a type symbol that is used in
891 func (l *Loader) AttrUsedInIface(i Sym) bool {
892 return l.attrUsedInIface.Has(i)
895 func (l *Loader) SetAttrUsedInIface(i Sym, v bool) {
897 l.attrUsedInIface.Set(i)
899 l.attrUsedInIface.Unset(i)
903 // SymAddr checks that a symbol is reachable, and returns its value.
904 func (l *Loader) SymAddr(i Sym) int64 {
905 if !l.AttrReachable(i) {
906 panic("unreachable symbol in symaddr")
911 // AttrNotInSymbolTable returns true for symbols that should not be
912 // added to the symbol table of the final generated load module.
913 func (l *Loader) AttrNotInSymbolTable(i Sym) bool {
914 return l.attrNotInSymbolTable.Has(i)
917 // SetAttrNotInSymbolTable the "not in symtab" property for a symbol
918 // (see AttrNotInSymbolTable above).
919 func (l *Loader) SetAttrNotInSymbolTable(i Sym, v bool) {
921 l.attrNotInSymbolTable.Set(i)
923 l.attrNotInSymbolTable.Unset(i)
927 // AttrVisibilityHidden symbols returns true for ELF symbols with
928 // visibility set to STV_HIDDEN. They become local symbols in
929 // the final executable. Only relevant when internally linking
930 // on an ELF platform.
931 func (l *Loader) AttrVisibilityHidden(i Sym) bool {
932 if !l.IsExternal(i) {
935 return l.attrVisibilityHidden.Has(l.extIndex(i))
938 // SetAttrVisibilityHidden sets the "hidden visibility" property for a
939 // symbol (see AttrVisibilityHidden).
940 func (l *Loader) SetAttrVisibilityHidden(i Sym, v bool) {
941 if !l.IsExternal(i) {
942 panic("tried to set visibility attr on non-external symbol")
945 l.attrVisibilityHidden.Set(l.extIndex(i))
947 l.attrVisibilityHidden.Unset(l.extIndex(i))
951 // AttrDuplicateOK returns true for a symbol that can be present in
952 // multiple object files.
953 func (l *Loader) AttrDuplicateOK(i Sym) bool {
954 if !l.IsExternal(i) {
955 // TODO: if this path winds up being taken frequently, it
956 // might make more sense to copy the flag value out of the object
957 // into a larger bitmap during preload.
958 r, li := l.toLocal(i)
959 return r.Sym(li).Dupok()
961 return l.attrDuplicateOK.Has(l.extIndex(i))
964 // SetAttrDuplicateOK sets the "duplicate OK" property for an external
965 // symbol (see AttrDuplicateOK).
966 func (l *Loader) SetAttrDuplicateOK(i Sym, v bool) {
967 if !l.IsExternal(i) {
968 panic("tried to set dupok attr on non-external symbol")
971 l.attrDuplicateOK.Set(l.extIndex(i))
973 l.attrDuplicateOK.Unset(l.extIndex(i))
977 // AttrShared returns true for symbols compiled with the -shared option.
978 func (l *Loader) AttrShared(i Sym) bool {
979 if !l.IsExternal(i) {
980 // TODO: if this path winds up being taken frequently, it
981 // might make more sense to copy the flag value out of the
982 // object into a larger bitmap during preload.
986 return l.attrShared.Has(l.extIndex(i))
989 // SetAttrShared sets the "shared" property for an external
990 // symbol (see AttrShared).
991 func (l *Loader) SetAttrShared(i Sym, v bool) {
992 if !l.IsExternal(i) {
993 panic(fmt.Sprintf("tried to set shared attr on non-external symbol %d %s", i, l.SymName(i)))
996 l.attrShared.Set(l.extIndex(i))
998 l.attrShared.Unset(l.extIndex(i))
1002 // AttrExternal returns true for function symbols loaded from host
1004 func (l *Loader) AttrExternal(i Sym) bool {
1005 if !l.IsExternal(i) {
1008 return l.attrExternal.Has(l.extIndex(i))
1011 // SetAttrExternal sets the "external" property for an host object
1012 // symbol (see AttrExternal).
1013 func (l *Loader) SetAttrExternal(i Sym, v bool) {
1014 if !l.IsExternal(i) {
1015 panic(fmt.Sprintf("tried to set external attr on non-external symbol %q", l.RawSymName(i)))
1018 l.attrExternal.Set(l.extIndex(i))
1020 l.attrExternal.Unset(l.extIndex(i))
1024 // AttrSpecial returns true for a symbols that do not have their
1025 // address (i.e. Value) computed by the usual mechanism of
1026 // data.go:dodata() & data.go:address().
1027 func (l *Loader) AttrSpecial(i Sym) bool {
1028 _, ok := l.attrSpecial[i]
1032 // SetAttrSpecial sets the "special" property for a symbol (see
1034 func (l *Loader) SetAttrSpecial(i Sym, v bool) {
1036 l.attrSpecial[i] = struct{}{}
1038 delete(l.attrSpecial, i)
1042 // AttrCgoExportDynamic returns true for a symbol that has been
1043 // specially marked via the "cgo_export_dynamic" compiler directive
1044 // written by cgo (in response to //export directives in the source).
1045 func (l *Loader) AttrCgoExportDynamic(i Sym) bool {
1046 _, ok := l.attrCgoExportDynamic[i]
1050 // SetAttrCgoExportDynamic sets the "cgo_export_dynamic" for a symbol
1051 // (see AttrCgoExportDynamic).
1052 func (l *Loader) SetAttrCgoExportDynamic(i Sym, v bool) {
1054 l.attrCgoExportDynamic[i] = struct{}{}
1056 delete(l.attrCgoExportDynamic, i)
1060 // AttrCgoExportStatic returns true for a symbol that has been
1061 // specially marked via the "cgo_export_static" directive
1063 func (l *Loader) AttrCgoExportStatic(i Sym) bool {
1064 _, ok := l.attrCgoExportStatic[i]
1068 // SetAttrCgoExportStatic sets the "cgo_export_static" for a symbol
1069 // (see AttrCgoExportStatic).
1070 func (l *Loader) SetAttrCgoExportStatic(i Sym, v bool) {
1072 l.attrCgoExportStatic[i] = struct{}{}
1074 delete(l.attrCgoExportStatic, i)
1078 // IsGeneratedSym returns true if a symbol's been previously marked as a
1079 // generator symbol through the SetIsGeneratedSym. The functions for generator
1080 // symbols are kept in the Link context.
1081 func (l *Loader) IsGeneratedSym(i Sym) bool {
1082 _, ok := l.generatedSyms[i]
1086 // SetIsGeneratedSym marks symbols as generated symbols. Data shouldn't be
1087 // stored in generated symbols, and a function is registered and called for
1088 // each of these symbols.
1089 func (l *Loader) SetIsGeneratedSym(i Sym, v bool) {
1090 if !l.IsExternal(i) {
1091 panic("only external symbols can be generated")
1094 l.generatedSyms[i] = struct{}{}
1096 delete(l.generatedSyms, i)
1100 func (l *Loader) AttrCgoExport(i Sym) bool {
1101 return l.AttrCgoExportDynamic(i) || l.AttrCgoExportStatic(i)
1104 // AttrReadOnly returns true for a symbol whose underlying data
1105 // is stored via a read-only mmap.
1106 func (l *Loader) AttrReadOnly(i Sym) bool {
1107 if v, ok := l.attrReadOnly[i]; ok {
1110 if l.IsExternal(i) {
1111 pp := l.getPayload(i)
1113 return l.objs[pp.objidx].r.ReadOnly()
1117 r, _ := l.toLocal(i)
1121 // SetAttrReadOnly sets the "data is read only" property for a symbol
1122 // (see AttrReadOnly).
1123 func (l *Loader) SetAttrReadOnly(i Sym, v bool) {
1124 l.attrReadOnly[i] = v
1127 // AttrSubSymbol returns true for symbols that are listed as a
1128 // sub-symbol of some other outer symbol. The sub/outer mechanism is
1129 // used when loading host objects (sections from the host object
1130 // become regular linker symbols and symbols go on the Sub list of
1131 // their section) and for constructing the global offset table when
1132 // internally linking a dynamic executable.
1134 // Note that in later stages of the linker, we set Outer(S) to some
1135 // container symbol C, but don't set Sub(C). Thus we have two
1136 // distinct scenarios:
1138 // - Outer symbol covers the address ranges of its sub-symbols.
1139 // Outer.Sub is set in this case.
1140 // - Outer symbol doesn't conver the address ranges. It is zero-sized
1141 // and doesn't have sub-symbols. In the case, the inner symbol is
1142 // not actually a "SubSymbol". (Tricky!)
1144 // This method returns TRUE only for sub-symbols in the first scenario.
1146 // FIXME: would be better to do away with this and have a better way
1147 // to represent container symbols.
1149 func (l *Loader) AttrSubSymbol(i Sym) bool {
1150 // we don't explicitly store this attribute any more -- return
1151 // a value based on the sub-symbol setting.
1156 return l.SubSym(o) != 0
1159 // Note that we don't have a 'SetAttrSubSymbol' method in the loader;
1160 // clients should instead use the AddInteriorSym method to establish
1161 // containment relationships for host object symbols.
1163 // Returns whether the i-th symbol has ReflectMethod attribute set.
1164 func (l *Loader) IsReflectMethod(i Sym) bool {
1165 return l.SymAttr(i)&goobj.SymFlagReflectMethod != 0
1168 // Returns whether the i-th symbol is nosplit.
1169 func (l *Loader) IsNoSplit(i Sym) bool {
1170 return l.SymAttr(i)&goobj.SymFlagNoSplit != 0
1173 // Returns whether this is a Go type symbol.
1174 func (l *Loader) IsGoType(i Sym) bool {
1175 return l.SymAttr(i)&goobj.SymFlagGoType != 0
1178 // Returns whether this symbol should be included in typelink.
1179 func (l *Loader) IsTypelink(i Sym) bool {
1180 return l.SymAttr(i)&goobj.SymFlagTypelink != 0
1183 // Returns whether this symbol is an itab symbol.
1184 func (l *Loader) IsItab(i Sym) bool {
1185 if l.IsExternal(i) {
1188 r, li := l.toLocal(i)
1189 return r.Sym(li).IsItab()
1192 // Returns whether this symbol is a dictionary symbol.
1193 func (l *Loader) IsDict(i Sym) bool {
1194 if l.IsExternal(i) {
1197 r, li := l.toLocal(i)
1198 return r.Sym(li).IsDict()
1201 // Return whether this is a trampoline of a deferreturn call.
1202 func (l *Loader) IsDeferReturnTramp(i Sym) bool {
1203 return l.deferReturnTramp[i]
1206 // Set that i is a trampoline of a deferreturn call.
1207 func (l *Loader) SetIsDeferReturnTramp(i Sym, v bool) {
1208 l.deferReturnTramp[i] = v
1211 // growValues grows the slice used to store symbol values.
1212 func (l *Loader) growValues(reqLen int) {
1213 curLen := len(l.values)
1214 if reqLen > curLen {
1215 l.values = append(l.values, make([]int64, reqLen+1-curLen)...)
1219 // SymValue returns the value of the i-th symbol. i is global index.
1220 func (l *Loader) SymValue(i Sym) int64 {
1224 // SetSymValue sets the value of the i-th symbol. i is global index.
1225 func (l *Loader) SetSymValue(i Sym, val int64) {
1229 // AddToSymValue adds to the value of the i-th symbol. i is the global index.
1230 func (l *Loader) AddToSymValue(i Sym, val int64) {
1234 // Returns the symbol content of the i-th symbol. i is global index.
1235 func (l *Loader) Data(i Sym) []byte {
1236 if l.IsExternal(i) {
1237 pp := l.getPayload(i)
1243 r, li := l.toLocal(i)
1247 // FreeData clears the symbol data of an external symbol, allowing the memory
1248 // to be freed earlier. No-op for non-external symbols.
1249 // i is global index.
1250 func (l *Loader) FreeData(i Sym) {
1251 if l.IsExternal(i) {
1252 pp := l.getPayload(i)
1259 // SymAlign returns the alignment for a symbol.
1260 func (l *Loader) SymAlign(i Sym) int32 {
1261 if int(i) >= len(l.align) {
1262 // align is extended lazily -- it the sym in question is
1263 // outside the range of the existing slice, then we assume its
1264 // alignment has not yet been set.
1267 // TODO: would it make sense to return an arch-specific
1268 // alignment depending on section type? E.g. STEXT => 32,
1274 return int32(1 << (abits - 1))
1277 // SetSymAlign sets the alignment for a symbol.
1278 func (l *Loader) SetSymAlign(i Sym, align int32) {
1279 // Reject nonsense alignments.
1280 if align < 0 || align&(align-1) != 0 {
1281 panic("bad alignment value")
1283 if int(i) >= len(l.align) {
1284 l.align = append(l.align, make([]uint8, l.NSym()-len(l.align))...)
1289 l.align[i] = uint8(bits.Len32(uint32(align)))
1292 // SymValue returns the section of the i-th symbol. i is global index.
1293 func (l *Loader) SymSect(i Sym) *sym.Section {
1294 if int(i) >= len(l.symSects) {
1295 // symSects is extended lazily -- it the sym in question is
1296 // outside the range of the existing slice, then we assume its
1297 // section has not yet been set.
1300 return l.sects[l.symSects[i]]
1303 // SetSymSect sets the section of the i-th symbol. i is global index.
1304 func (l *Loader) SetSymSect(i Sym, sect *sym.Section) {
1305 if int(i) >= len(l.symSects) {
1306 l.symSects = append(l.symSects, make([]uint16, l.NSym()-len(l.symSects))...)
1308 l.symSects[i] = sect.Index
1311 // growSects grows the slice used to store symbol sections.
1312 func (l *Loader) growSects(reqLen int) {
1313 curLen := len(l.symSects)
1314 if reqLen > curLen {
1315 l.symSects = append(l.symSects, make([]uint16, reqLen+1-curLen)...)
1319 // NewSection creates a new (output) section.
1320 func (l *Loader) NewSection() *sym.Section {
1321 sect := new(sym.Section)
1323 if idx != int(uint16(idx)) {
1324 panic("too many sections created")
1326 sect.Index = uint16(idx)
1327 l.sects = append(l.sects, sect)
1331 // SymDynImplib returns the "dynimplib" attribute for the specified
1332 // symbol, making up a portion of the info for a symbol specified
1333 // on a "cgo_import_dynamic" compiler directive.
1334 func (l *Loader) SymDynimplib(i Sym) string {
1335 return l.dynimplib[i]
1338 // SetSymDynimplib sets the "dynimplib" attribute for a symbol.
1339 func (l *Loader) SetSymDynimplib(i Sym, value string) {
1340 // reject bad symbols
1341 if i >= Sym(len(l.objSyms)) || i == 0 {
1342 panic("bad symbol index in SetDynimplib")
1345 delete(l.dynimplib, i)
1347 l.dynimplib[i] = value
1351 // SymDynimpvers returns the "dynimpvers" attribute for the specified
1352 // symbol, making up a portion of the info for a symbol specified
1353 // on a "cgo_import_dynamic" compiler directive.
1354 func (l *Loader) SymDynimpvers(i Sym) string {
1355 return l.dynimpvers[i]
1358 // SetSymDynimpvers sets the "dynimpvers" attribute for a symbol.
1359 func (l *Loader) SetSymDynimpvers(i Sym, value string) {
1360 // reject bad symbols
1361 if i >= Sym(len(l.objSyms)) || i == 0 {
1362 panic("bad symbol index in SetDynimpvers")
1365 delete(l.dynimpvers, i)
1367 l.dynimpvers[i] = value
1371 // SymExtname returns the "extname" value for the specified
1373 func (l *Loader) SymExtname(i Sym) string {
1374 if s, ok := l.extname[i]; ok {
1380 // SetSymExtname sets the "extname" attribute for a symbol.
1381 func (l *Loader) SetSymExtname(i Sym, value string) {
1382 // reject bad symbols
1383 if i >= Sym(len(l.objSyms)) || i == 0 {
1384 panic("bad symbol index in SetExtname")
1387 delete(l.extname, i)
1389 l.extname[i] = value
1393 // SymElfType returns the previously recorded ELF type for a symbol
1394 // (used only for symbols read from shared libraries by ldshlibsyms).
1395 // It is not set for symbols defined by the packages being linked or
1396 // by symbols read by ldelf (and so is left as elf.STT_NOTYPE).
1397 func (l *Loader) SymElfType(i Sym) elf.SymType {
1398 if et, ok := l.elfType[i]; ok {
1401 return elf.STT_NOTYPE
1404 // SetSymElfType sets the elf type attribute for a symbol.
1405 func (l *Loader) SetSymElfType(i Sym, et elf.SymType) {
1406 // reject bad symbols
1407 if i >= Sym(len(l.objSyms)) || i == 0 {
1408 panic("bad symbol index in SetSymElfType")
1410 if et == elf.STT_NOTYPE {
1411 delete(l.elfType, i)
1417 // SymElfSym returns the ELF symbol index for a given loader
1418 // symbol, assigned during ELF symtab generation.
1419 func (l *Loader) SymElfSym(i Sym) int32 {
1423 // SetSymElfSym sets the elf symbol index for a symbol.
1424 func (l *Loader) SetSymElfSym(i Sym, es int32) {
1426 panic("bad sym index")
1435 // SymLocalElfSym returns the "local" ELF symbol index for a given loader
1436 // symbol, assigned during ELF symtab generation.
1437 func (l *Loader) SymLocalElfSym(i Sym) int32 {
1438 return l.localElfSym[i]
1441 // SetSymLocalElfSym sets the "local" elf symbol index for a symbol.
1442 func (l *Loader) SetSymLocalElfSym(i Sym, es int32) {
1444 panic("bad sym index")
1447 delete(l.localElfSym, i)
1449 l.localElfSym[i] = es
1453 // SymPlt returns the PLT offset of symbol s.
1454 func (l *Loader) SymPlt(s Sym) int32 {
1455 if v, ok := l.plt[s]; ok {
1461 // SetPlt sets the PLT offset of symbol i.
1462 func (l *Loader) SetPlt(i Sym, v int32) {
1463 if i >= Sym(len(l.objSyms)) || i == 0 {
1464 panic("bad symbol for SetPlt")
1473 // SymGot returns the GOT offset of symbol s.
1474 func (l *Loader) SymGot(s Sym) int32 {
1475 if v, ok := l.got[s]; ok {
1481 // SetGot sets the GOT offset of symbol i.
1482 func (l *Loader) SetGot(i Sym, v int32) {
1483 if i >= Sym(len(l.objSyms)) || i == 0 {
1484 panic("bad symbol for SetGot")
1493 // SymDynid returns the "dynid" property for the specified symbol.
1494 func (l *Loader) SymDynid(i Sym) int32 {
1495 if s, ok := l.dynid[i]; ok {
1501 // SetSymDynid sets the "dynid" property for a symbol.
1502 func (l *Loader) SetSymDynid(i Sym, val int32) {
1503 // reject bad symbols
1504 if i >= Sym(len(l.objSyms)) || i == 0 {
1505 panic("bad symbol index in SetSymDynid")
1514 // DynIdSyms returns the set of symbols for which dynID is set to an
1515 // interesting (non-default) value. This is expected to be a fairly
1517 func (l *Loader) DynidSyms() []Sym {
1518 sl := make([]Sym, 0, len(l.dynid))
1519 for s := range l.dynid {
1522 sort.Slice(sl, func(i, j int) bool { return sl[i] < sl[j] })
1526 // SymGoType returns the 'Gotype' property for a given symbol (set by
1527 // the Go compiler for variable symbols). This version relies on
1528 // reading aux symbols for the target sym -- it could be that a faster
1529 // approach would be to check for gotype during preload and copy the
1530 // results in to a map (might want to try this at some point and see
1531 // if it helps speed things up).
1532 func (l *Loader) SymGoType(i Sym) Sym { return l.aux1(i, goobj.AuxGotype) }
1534 // SymUnit returns the compilation unit for a given symbol (which will
1535 // typically be nil for external or linker-manufactured symbols).
1536 func (l *Loader) SymUnit(i Sym) *sym.CompilationUnit {
1537 if l.IsExternal(i) {
1538 pp := l.getPayload(i)
1540 r := l.objs[pp.objidx].r
1545 r, _ := l.toLocal(i)
1549 // SymPkg returns the package where the symbol came from (for
1550 // regular compiler-generated Go symbols), but in the case of
1551 // building with "-linkshared" (when a symbol is read from a
1552 // shared library), will hold the library name.
1553 // NOTE: this corresponds to sym.Symbol.File field.
1554 func (l *Loader) SymPkg(i Sym) string {
1555 if f, ok := l.symPkg[i]; ok {
1558 if l.IsExternal(i) {
1559 pp := l.getPayload(i)
1561 r := l.objs[pp.objidx].r
1562 return r.unit.Lib.Pkg
1566 r, _ := l.toLocal(i)
1567 return r.unit.Lib.Pkg
1570 // SetSymPkg sets the package/library for a symbol. This is
1571 // needed mainly for external symbols, specifically those imported
1572 // from shared libraries.
1573 func (l *Loader) SetSymPkg(i Sym, pkg string) {
1574 // reject bad symbols
1575 if i >= Sym(len(l.objSyms)) || i == 0 {
1576 panic("bad symbol index in SetSymPkg")
1581 // SymLocalentry returns the "local entry" value for the specified
1583 func (l *Loader) SymLocalentry(i Sym) uint8 {
1584 return l.localentry[i]
1587 // SetSymLocalentry sets the "local entry" attribute for a symbol.
1588 func (l *Loader) SetSymLocalentry(i Sym, value uint8) {
1589 // reject bad symbols
1590 if i >= Sym(len(l.objSyms)) || i == 0 {
1591 panic("bad symbol index in SetSymLocalentry")
1594 delete(l.localentry, i)
1596 l.localentry[i] = value
1600 // Returns the number of aux symbols given a global index.
1601 func (l *Loader) NAux(i Sym) int {
1602 if l.IsExternal(i) {
1605 r, li := l.toLocal(i)
1609 // Returns the "handle" to the j-th aux symbol of the i-th symbol.
1610 func (l *Loader) Aux(i Sym, j int) Aux {
1611 if l.IsExternal(i) {
1614 r, li := l.toLocal(i)
1615 if j >= r.NAux(li) {
1618 return Aux{r.Aux(li, j), r, l}
1621 // GetFuncDwarfAuxSyms collects and returns the auxiliary DWARF
1622 // symbols associated with a given function symbol. Prior to the
1623 // introduction of the loader, this was done purely using name
1624 // lookups, e.f. for function with name XYZ we would then look up
1625 // go.info.XYZ, etc.
1626 func (l *Loader) GetFuncDwarfAuxSyms(fnSymIdx Sym) (auxDwarfInfo, auxDwarfLoc, auxDwarfRanges, auxDwarfLines Sym) {
1627 if l.SymType(fnSymIdx) != sym.STEXT {
1628 log.Fatalf("error: non-function sym %d/%s t=%s passed to GetFuncDwarfAuxSyms", fnSymIdx, l.SymName(fnSymIdx), l.SymType(fnSymIdx).String())
1630 if l.IsExternal(fnSymIdx) {
1631 // Current expectation is that any external function will
1632 // not have auxsyms.
1635 r, li := l.toLocal(fnSymIdx)
1637 for i := range auxs {
1640 case goobj.AuxDwarfInfo:
1641 auxDwarfInfo = l.resolve(r, a.Sym())
1642 if l.SymType(auxDwarfInfo) != sym.SDWARFFCN {
1643 panic("aux dwarf info sym with wrong type")
1645 case goobj.AuxDwarfLoc:
1646 auxDwarfLoc = l.resolve(r, a.Sym())
1647 if l.SymType(auxDwarfLoc) != sym.SDWARFLOC {
1648 panic("aux dwarf loc sym with wrong type")
1650 case goobj.AuxDwarfRanges:
1651 auxDwarfRanges = l.resolve(r, a.Sym())
1652 if l.SymType(auxDwarfRanges) != sym.SDWARFRANGE {
1653 panic("aux dwarf ranges sym with wrong type")
1655 case goobj.AuxDwarfLines:
1656 auxDwarfLines = l.resolve(r, a.Sym())
1657 if l.SymType(auxDwarfLines) != sym.SDWARFLINES {
1658 panic("aux dwarf lines sym with wrong type")
1665 // AddInteriorSym sets up 'interior' as an interior symbol of
1666 // container/payload symbol 'container'. An interior symbol does not
1667 // itself have data, but gives a name to a subrange of the data in its
1668 // container symbol. The container itself may or may not have a name.
1669 // This method is intended primarily for use in the host object
1670 // loaders, to capture the semantics of symbols and sections in an
1671 // object file. When reading a host object file, we'll typically
1672 // encounter a static section symbol (ex: ".text") containing content
1673 // for a collection of functions, then a series of ELF (or macho, etc)
1674 // symbol table entries each of which points into a sub-section
1675 // (offset and length) of its corresponding container symbol. Within
1676 // the go linker we create a loader.Sym for the container (which is
1677 // expected to have the actual content/payload) and then a set of
1678 // interior loader.Sym's that point into a portion of the container.
1679 func (l *Loader) AddInteriorSym(container Sym, interior Sym) {
1680 // Container symbols are expected to have content/data.
1681 // NB: this restriction may turn out to be too strict (it's possible
1682 // to imagine a zero-sized container with an interior symbol pointing
1683 // into it); it's ok to relax or remove it if we counter an
1684 // oddball host object that triggers this.
1685 if l.SymSize(container) == 0 && len(l.Data(container)) == 0 {
1686 panic("unexpected empty container symbol")
1688 // The interior symbols for a container are not expected to have
1689 // content/data or relocations.
1690 if len(l.Data(interior)) != 0 {
1691 panic("unexpected non-empty interior symbol")
1693 // Interior symbol is expected to be in the symbol table.
1694 if l.AttrNotInSymbolTable(interior) {
1695 panic("interior symbol must be in symtab")
1697 // Only a single level of containment is allowed.
1698 if l.OuterSym(container) != 0 {
1699 panic("outer has outer itself")
1701 // Interior sym should not already have a sibling.
1702 if l.SubSym(interior) != 0 {
1703 panic("sub set for subsym")
1705 // Interior sym should not already point at a container.
1706 if l.OuterSym(interior) != 0 {
1707 panic("outer already set for subsym")
1709 l.sub[interior] = l.sub[container]
1710 l.sub[container] = interior
1711 l.outer[interior] = container
1714 // OuterSym gets the outer symbol for host object loaded symbols.
1715 func (l *Loader) OuterSym(i Sym) Sym {
1716 // FIXME: add check for isExternal?
1720 // SubSym gets the subsymbol for host object loaded symbols.
1721 func (l *Loader) SubSym(i Sym) Sym {
1722 // NB: note -- no check for l.isExternal(), since I am pretty sure
1723 // that later phases in the linker set subsym for "type." syms
1727 // SetCarrierSym declares that 'c' is the carrier or container symbol
1728 // for 's'. Carrier symbols are used in the linker to as a container
1729 // for a collection of sub-symbols where the content of the
1730 // sub-symbols is effectively concatenated to form the content of the
1731 // carrier. The carrier is given a name in the output symbol table
1732 // while the sub-symbol names are not. For example, the Go compiler
1733 // emits named string symbols (type SGOSTRING) when compiling a
1734 // package; after being deduplicated, these symbols are collected into
1735 // a single unit by assigning them a new carrier symbol named
1736 // "go.string.*" (which appears in the final symbol table for the
1737 // output load module).
1738 func (l *Loader) SetCarrierSym(s Sym, c Sym) {
1740 panic("invalid carrier in SetCarrierSym")
1743 panic("invalid sub-symbol in SetCarrierSym")
1745 // Carrier symbols are not expected to have content/data. It is
1746 // ok for them to have non-zero size (to allow for use of generator
1748 if len(l.Data(c)) != 0 {
1749 panic("unexpected non-empty carrier symbol")
1752 // relocsym's foldSubSymbolOffset requires that we only
1753 // have a single level of containment-- enforce here.
1754 if l.outer[c] != 0 {
1755 panic("invalid nested carrier sym")
1759 // Initialize Reachable bitmap and its siblings for running deadcode pass.
1760 func (l *Loader) InitReachable() {
1761 l.growAttrBitmaps(l.NSym() + 1)
1764 type symWithVal struct {
1768 type bySymValue []symWithVal
1770 func (s bySymValue) Len() int { return len(s) }
1771 func (s bySymValue) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
1772 func (s bySymValue) Less(i, j int) bool { return s[i].v < s[j].v }
1774 // SortSub walks through the sub-symbols for 's' and sorts them
1775 // in place by increasing value. Return value is the new
1776 // sub symbol for the specified outer symbol.
1777 func (l *Loader) SortSub(s Sym) Sym {
1779 if s == 0 || l.sub[s] == 0 {
1783 // Sort symbols using a slice first. Use a stable sort on the off
1784 // chance that there's more than once symbol with the same value,
1785 // so as to preserve reproducible builds.
1786 sl := []symWithVal{}
1787 for ss := l.sub[s]; ss != 0; ss = l.sub[ss] {
1788 sl = append(sl, symWithVal{s: ss, v: l.SymValue(ss)})
1790 sort.Stable(bySymValue(sl))
1792 // Then apply any changes needed to the sub map.
1794 for i := len(sl) - 1; i >= 0; i-- {
1800 // Update sub for outer symbol, then return
1805 // SortSyms sorts a list of symbols by their value.
1806 func (l *Loader) SortSyms(ss []Sym) {
1807 sort.SliceStable(ss, func(i, j int) bool { return l.SymValue(ss[i]) < l.SymValue(ss[j]) })
1810 // Insure that reachable bitmap and its siblings have enough size.
1811 func (l *Loader) growAttrBitmaps(reqLen int) {
1812 if reqLen > l.attrReachable.Len() {
1813 // These are indexed by global symbol
1814 l.attrReachable = growBitmap(reqLen, l.attrReachable)
1815 l.attrOnList = growBitmap(reqLen, l.attrOnList)
1816 l.attrLocal = growBitmap(reqLen, l.attrLocal)
1817 l.attrNotInSymbolTable = growBitmap(reqLen, l.attrNotInSymbolTable)
1818 l.attrUsedInIface = growBitmap(reqLen, l.attrUsedInIface)
1820 l.growExtAttrBitmaps()
1823 func (l *Loader) growExtAttrBitmaps() {
1824 // These are indexed by external symbol index (e.g. l.extIndex(i))
1825 extReqLen := len(l.payloads)
1826 if extReqLen > l.attrVisibilityHidden.Len() {
1827 l.attrVisibilityHidden = growBitmap(extReqLen, l.attrVisibilityHidden)
1828 l.attrDuplicateOK = growBitmap(extReqLen, l.attrDuplicateOK)
1829 l.attrShared = growBitmap(extReqLen, l.attrShared)
1830 l.attrExternal = growBitmap(extReqLen, l.attrExternal)
1834 func (relocs *Relocs) Count() int { return len(relocs.rs) }
1836 // At returns the j-th reloc for a global symbol.
1837 func (relocs *Relocs) At(j int) Reloc {
1838 if relocs.l.isExtReader(relocs.r) {
1839 return Reloc{&relocs.rs[j], relocs.r, relocs.l}
1841 return Reloc{&relocs.rs[j], relocs.r, relocs.l}
1844 // Relocs returns a Relocs object for the given global sym.
1845 func (l *Loader) Relocs(i Sym) Relocs {
1846 r, li := l.toLocal(i)
1848 panic(fmt.Sprintf("trying to get oreader for invalid sym %d\n\n", i))
1850 return l.relocs(r, li)
1853 // Relocs returns a Relocs object given a local sym index and reader.
1854 func (l *Loader) relocs(r *oReader, li uint32) Relocs {
1855 var rs []goobj.Reloc
1856 if l.isExtReader(r) {
1857 pp := l.payloads[li]
1870 func (l *Loader) auxs(i Sym) (*oReader, []goobj.Aux) {
1871 if l.IsExternal(i) {
1872 pp := l.getPayload(i)
1873 return l.objs[pp.objidx].r, pp.auxs
1875 r, li := l.toLocal(i)
1876 return r, r.Auxs(li)
1880 // Returns a specific aux symbol of type t for symbol i.
1881 func (l *Loader) aux1(i Sym, t uint8) Sym {
1882 r, auxs := l.auxs(i)
1883 for j := range auxs {
1886 return l.resolve(r, a.Sym())
1892 func (l *Loader) Pcsp(i Sym) Sym { return l.aux1(i, goobj.AuxPcsp) }
1894 // Returns all aux symbols of per-PC data for symbol i.
1895 // tmp is a scratch space for the pcdata slice.
1896 func (l *Loader) PcdataAuxs(i Sym, tmp []Sym) (pcsp, pcfile, pcline, pcinline Sym, pcdata []Sym) {
1898 r, auxs := l.auxs(i)
1899 for j := range auxs {
1903 pcsp = l.resolve(r, a.Sym())
1904 case goobj.AuxPcline:
1905 pcline = l.resolve(r, a.Sym())
1906 case goobj.AuxPcfile:
1907 pcfile = l.resolve(r, a.Sym())
1908 case goobj.AuxPcinline:
1909 pcinline = l.resolve(r, a.Sym())
1910 case goobj.AuxPcdata:
1911 pcdata = append(pcdata, l.resolve(r, a.Sym()))
1917 // Returns the number of pcdata for symbol i.
1918 func (l *Loader) NumPcdata(i Sym) int {
1920 _, auxs := l.auxs(i)
1921 for j := range auxs {
1923 if a.Type() == goobj.AuxPcdata {
1930 // Returns all funcdata symbols of symbol i.
1931 // tmp is a scratch space.
1932 func (l *Loader) Funcdata(i Sym, tmp []Sym) []Sym {
1934 r, auxs := l.auxs(i)
1935 for j := range auxs {
1937 if a.Type() == goobj.AuxFuncdata {
1938 fd = append(fd, l.resolve(r, a.Sym()))
1944 // Returns the number of funcdata for symbol i.
1945 func (l *Loader) NumFuncdata(i Sym) int {
1947 _, auxs := l.auxs(i)
1948 for j := range auxs {
1950 if a.Type() == goobj.AuxFuncdata {
1957 // FuncInfo provides hooks to access goobj.FuncInfo in the objects.
1958 type FuncInfo struct {
1962 lengths goobj.FuncInfoLengths
1965 func (fi *FuncInfo) Valid() bool { return fi.r != nil }
1967 func (fi *FuncInfo) Args() int {
1968 return int((*goobj.FuncInfo)(nil).ReadArgs(fi.data))
1971 func (fi *FuncInfo) Locals() int {
1972 return int((*goobj.FuncInfo)(nil).ReadLocals(fi.data))
1975 func (fi *FuncInfo) FuncID() objabi.FuncID {
1976 return (*goobj.FuncInfo)(nil).ReadFuncID(fi.data)
1979 func (fi *FuncInfo) FuncFlag() objabi.FuncFlag {
1980 return (*goobj.FuncInfo)(nil).ReadFuncFlag(fi.data)
1983 // Preload has to be called prior to invoking the various methods
1984 // below related to pcdata, funcdataoff, files, and inltree nodes.
1985 func (fi *FuncInfo) Preload() {
1986 fi.lengths = (*goobj.FuncInfo)(nil).ReadFuncInfoLengths(fi.data)
1989 func (fi *FuncInfo) NumFile() uint32 {
1990 if !fi.lengths.Initialized {
1991 panic("need to call Preload first")
1993 return fi.lengths.NumFile
1996 func (fi *FuncInfo) File(k int) goobj.CUFileIndex {
1997 if !fi.lengths.Initialized {
1998 panic("need to call Preload first")
2000 return (*goobj.FuncInfo)(nil).ReadFile(fi.data, fi.lengths.FileOff, uint32(k))
2003 // TopFrame returns true if the function associated with this FuncInfo
2004 // is an entry point, meaning that unwinders should stop when they hit
2006 func (fi *FuncInfo) TopFrame() bool {
2007 return (fi.FuncFlag() & objabi.FuncFlag_TOPFRAME) != 0
2010 type InlTreeNode struct {
2012 File goobj.CUFileIndex
2018 func (fi *FuncInfo) NumInlTree() uint32 {
2019 if !fi.lengths.Initialized {
2020 panic("need to call Preload first")
2022 return fi.lengths.NumInlTree
2025 func (fi *FuncInfo) InlTree(k int) InlTreeNode {
2026 if !fi.lengths.Initialized {
2027 panic("need to call Preload first")
2029 node := (*goobj.FuncInfo)(nil).ReadInlTree(fi.data, fi.lengths.InlTreeOff, uint32(k))
2031 Parent: node.Parent,
2034 Func: fi.l.resolve(fi.r, node.Func),
2035 ParentPC: node.ParentPC,
2039 func (l *Loader) FuncInfo(i Sym) FuncInfo {
2040 r, auxs := l.auxs(i)
2041 for j := range auxs {
2043 if a.Type() == goobj.AuxFuncInfo {
2044 b := r.Data(a.Sym().SymIdx)
2045 return FuncInfo{l, r, b, goobj.FuncInfoLengths{}}
2051 // Preload a package: adds autolib.
2052 // Does not add defined package or non-packaged symbols to the symbol table.
2053 // These are done in LoadSyms.
2054 // Does not read symbol data.
2055 // Returns the fingerprint of the object.
2056 func (l *Loader) Preload(localSymVersion int, f *bio.Reader, lib *sym.Library, unit *sym.CompilationUnit, length int64) goobj.FingerprintType {
2057 roObject, readonly, err := f.Slice(uint64(length)) // TODO: no need to map blocks that are for tools only (e.g. RefName)
2059 log.Fatal("cannot read object file:", err)
2061 r := goobj.NewReaderFromBytes(roObject, readonly)
2063 if len(roObject) >= 8 && bytes.Equal(roObject[:8], []byte("\x00go114ld")) {
2064 log.Fatalf("found object file %s in old format", f.File().Name())
2066 panic("cannot read object file")
2068 pkgprefix := objabi.PathToPrefix(lib.Pkg) + "."
2070 nhashed64def := r.NHashed64def()
2071 nhasheddef := r.NHasheddef()
2075 version: localSymVersion,
2076 pkgprefix: pkgprefix,
2077 syms: make([]Sym, ndef+nhashed64def+nhasheddef+r.NNonpkgdef()+r.NNonpkgref()),
2079 nhasheddef: nhasheddef,
2080 nhashed64def: nhashed64def,
2081 objidx: uint32(len(l.objs)),
2085 log.Fatalf("link: unlinkable object (from package %s) - compiler requires -p flag", lib.Pkg)
2089 lib.Autolib = append(lib.Autolib, r.Autolib()...)
2093 unit.FileTable = make([]string, nfile)
2094 for i := range unit.FileTable {
2095 unit.FileTable[i] = r.File(i)
2098 l.addObj(lib.Pkg, or)
2100 // The caller expects us consuming all the data
2101 f.MustSeek(length, os.SEEK_CUR)
2103 return r.Fingerprint()
2106 // Holds the loader along with temporary states for loading symbols.
2107 type loadState struct {
2109 hashed64Syms map[uint64]symAndSize // short hashed (content-addressable) symbols, keyed by content hash
2110 hashedSyms map[goobj.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
2113 // Preload symbols of given kind from an object.
2114 func (st *loadState) preloadSyms(r *oReader, kind int) {
2116 var start, end uint32
2120 end = uint32(r.ndef)
2122 start = uint32(r.ndef)
2123 end = uint32(r.ndef + r.nhashed64def)
2125 start = uint32(r.ndef + r.nhashed64def)
2126 end = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
2128 start = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
2129 end = uint32(r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef())
2131 panic("preloadSyms: bad kind")
2133 l.growAttrBitmaps(len(l.objSyms) + int(end-start))
2134 needNameExpansion := r.NeedNameExpansion()
2135 loadingRuntimePkg := r.unit.Lib.Pkg == "runtime"
2136 for i := start; i < end; i++ {
2140 if kind != hashed64Def && kind != hashedDef { // we don't need the name, etc. for hashed symbols
2141 name = osym.Name(r.Reader)
2142 if needNameExpansion {
2143 name = strings.Replace(name, "\"\".", r.pkgprefix, -1)
2145 v = abiToVer(osym.ABI(), r.version)
2147 gi := st.addSym(name, v, r, i, kind, osym)
2150 l.SetAttrLocal(gi, true)
2152 if osym.UsedInIface() {
2153 l.SetAttrUsedInIface(gi, true)
2155 if strings.HasPrefix(name, "runtime.") ||
2156 (loadingRuntimePkg && strings.HasPrefix(name, "type.")) {
2157 if bi := goobj.BuiltinIdx(name, int(osym.ABI())); bi != -1 {
2158 // This is a definition of a builtin symbol. Record where it is.
2159 l.builtinSyms[bi] = gi
2162 if a := int32(osym.Align()); a != 0 && a > l.SymAlign(gi) {
2163 l.SetSymAlign(gi, a)
2168 // Add syms, hashed (content-addressable) symbols, non-package symbols, and
2169 // references to external symbols (which are always named).
2170 func (l *Loader) LoadSyms(arch *sys.Arch) {
2171 // Allocate space for symbols, making a guess as to how much space we need.
2172 // This function was determined empirically by looking at the cmd/compile on
2173 // Darwin, and picking factors for hashed and hashed64 syms.
2174 var symSize, hashedSize, hashed64Size int
2175 for _, o := range l.objs[goObjStart:] {
2176 symSize += o.r.ndef + o.r.nhasheddef/2 + o.r.nhashed64def/2 + o.r.NNonpkgdef()
2177 hashedSize += o.r.nhasheddef / 2
2178 hashed64Size += o.r.nhashed64def / 2
2180 // Index 0 is invalid for symbols.
2181 l.objSyms = make([]objSym, 1, symSize)
2185 hashed64Syms: make(map[uint64]symAndSize, hashed64Size),
2186 hashedSyms: make(map[goobj.HashType]symAndSize, hashedSize),
2189 for _, o := range l.objs[goObjStart:] {
2190 st.preloadSyms(o.r, pkgDef)
2192 l.npkgsyms = l.NSym()
2193 for _, o := range l.objs[goObjStart:] {
2194 st.preloadSyms(o.r, hashed64Def)
2195 st.preloadSyms(o.r, hashedDef)
2196 st.preloadSyms(o.r, nonPkgDef)
2198 l.nhashedsyms = len(st.hashed64Syms) + len(st.hashedSyms)
2199 for _, o := range l.objs[goObjStart:] {
2200 loadObjRefs(l, o.r, arch)
2202 l.values = make([]int64, l.NSym(), l.NSym()+1000) // +1000 make some room for external symbols
2205 func loadObjRefs(l *Loader, r *oReader, arch *sys.Arch) {
2206 // load non-package refs
2207 ndef := uint32(r.NAlldef())
2208 needNameExpansion := r.NeedNameExpansion()
2209 for i, n := uint32(0), uint32(r.NNonpkgref()); i < n; i++ {
2210 osym := r.Sym(ndef + i)
2211 name := osym.Name(r.Reader)
2212 if needNameExpansion {
2213 name = strings.Replace(name, "\"\".", r.pkgprefix, -1)
2215 v := abiToVer(osym.ABI(), r.version)
2216 r.syms[ndef+i] = l.LookupOrCreateSym(name, v)
2217 gi := r.syms[ndef+i]
2219 l.SetAttrLocal(gi, true)
2221 if osym.UsedInIface() {
2222 l.SetAttrUsedInIface(gi, true)
2226 // referenced packages
2228 r.pkg = make([]uint32, npkg)
2229 for i := 1; i < npkg; i++ { // PkgIdx 0 is a dummy invalid package
2231 objidx, ok := l.objByPkg[pkg]
2233 log.Fatalf("%v: reference to nonexistent package %s", r.unit.Lib, pkg)
2238 // load flags of package refs
2239 for i, n := 0, r.NRefFlags(); i < n; i++ {
2241 gi := l.resolve(r, rf.Sym())
2242 if rf.Flag2()&goobj.SymFlagUsedInIface != 0 {
2243 l.SetAttrUsedInIface(gi, true)
2248 func abiToVer(abi uint16, localSymVersion int) int {
2250 if abi == goobj.SymABIstatic {
2253 } else if abiver := sym.ABIToVersion(obj.ABI(abi)); abiver != -1 {
2254 // Note that data symbols are "ABI0", which maps to version 0.
2257 log.Fatalf("invalid symbol ABI: %d", abi)
2262 // TopLevelSym tests a symbol (by name and kind) to determine whether
2263 // the symbol first class sym (participating in the link) or is an
2264 // anonymous aux or sub-symbol containing some sub-part or payload of
2266 func (l *Loader) TopLevelSym(s Sym) bool {
2267 return topLevelSym(l.RawSymName(s), l.SymType(s))
2270 // topLevelSym tests a symbol name and kind to determine whether
2271 // the symbol first class sym (participating in the link) or is an
2272 // anonymous aux or sub-symbol containing some sub-part or payload of
2274 func topLevelSym(sname string, skind sym.SymKind) bool {
2279 case sym.SDWARFFCN, sym.SDWARFABSFCN, sym.SDWARFTYPE, sym.SDWARFCONST, sym.SDWARFCUINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES, sym.SGOFUNC:
2286 // cloneToExternal takes the existing object file symbol (symIdx)
2287 // and creates a new external symbol payload that is a clone with
2288 // respect to name, version, type, relocations, etc. The idea here
2289 // is that if the linker decides it wants to update the contents of
2290 // a symbol originally discovered as part of an object file, it's
2291 // easier to do this if we make the updates to an external symbol
2293 func (l *Loader) cloneToExternal(symIdx Sym) {
2294 if l.IsExternal(symIdx) {
2295 panic("sym is already external, no need for clone")
2298 // Read the particulars from object.
2299 r, li := l.toLocal(symIdx)
2301 sname := osym.Name(r.Reader)
2302 if r.NeedNameExpansion() {
2303 sname = strings.Replace(sname, "\"\".", r.pkgprefix, -1)
2305 sver := abiToVer(osym.ABI(), r.version)
2306 skind := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
2308 // Create new symbol, update version and kind.
2309 pi := l.newPayload(sname, sver)
2310 pp := l.payloads[pi]
2313 pp.size = int64(osym.Siz())
2314 pp.objidx = r.objidx
2316 // If this is a def, then copy the guts. We expect this case
2317 // to be very rare (one case it may come up is with -X).
2318 if li < uint32(r.NAlldef()) {
2321 relocs := l.Relocs(symIdx)
2322 pp.relocs = make([]goobj.Reloc, relocs.Count())
2323 for i := range pp.relocs {
2324 // Copy the relocs slice.
2325 // Convert local reference to global reference.
2327 pp.relocs[i].Set(rel.Off(), rel.Siz(), uint16(rel.Type()), rel.Add(), goobj.SymRef{PkgIdx: 0, SymIdx: uint32(rel.Sym())})
2331 pp.data = r.Data(li)
2334 // If we're overriding a data symbol, collect the associated
2335 // Gotype, so as to propagate it to the new symbol.
2339 // Install new payload to global index space.
2340 // (This needs to happen at the end, as the accessors above
2341 // need to access the old symbol content.)
2342 l.objSyms[symIdx] = objSym{l.extReader.objidx, uint32(pi)}
2343 l.extReader.syms = append(l.extReader.syms, symIdx)
2345 // Some attributes were encoded in the object file. Copy them over.
2346 l.SetAttrDuplicateOK(symIdx, r.Sym(li).Dupok())
2347 l.SetAttrShared(symIdx, r.Shared())
2350 // Copy the payload of symbol src to dst. Both src and dst must be external
2352 // The intended use case is that when building/linking against a shared library,
2353 // where we do symbol name mangling, the Go object file may have reference to
2354 // the original symbol name whereas the shared library provides a symbol with
2355 // the mangled name. When we do mangling, we copy payload of mangled to original.
2356 func (l *Loader) CopySym(src, dst Sym) {
2357 if !l.IsExternal(dst) {
2358 panic("dst is not external") //l.newExtSym(l.SymName(dst), l.SymVersion(dst))
2360 if !l.IsExternal(src) {
2361 panic("src is not external") //l.cloneToExternal(src)
2363 l.payloads[l.extIndex(dst)] = l.payloads[l.extIndex(src)]
2364 l.SetSymPkg(dst, l.SymPkg(src))
2365 // TODO: other attributes?
2368 // CreateExtSym creates a new external symbol with the specified name
2369 // without adding it to any lookup tables, returning a Sym index for it.
2370 func (l *Loader) CreateExtSym(name string, ver int) Sym {
2371 return l.newExtSym(name, ver)
2374 // CreateStaticSym creates a new static symbol with the specified name
2375 // without adding it to any lookup tables, returning a Sym index for it.
2376 func (l *Loader) CreateStaticSym(name string) Sym {
2377 // Assign a new unique negative version -- this is to mark the
2378 // symbol so that it is not included in the name lookup table.
2380 return l.newExtSym(name, l.anonVersion)
2383 func (l *Loader) FreeSym(i Sym) {
2384 if l.IsExternal(i) {
2385 pp := l.getPayload(i)
2386 *pp = extSymPayload{}
2390 // relocId is essentially a <S,R> tuple identifying the Rth
2391 // relocation of symbol S.
2392 type relocId struct {
2397 // SetRelocVariant sets the 'variant' property of a relocation on
2398 // some specific symbol.
2399 func (l *Loader) SetRelocVariant(s Sym, ri int, v sym.RelocVariant) {
2401 if relocs := l.Relocs(s); ri >= relocs.Count() {
2402 panic("invalid relocation ID")
2404 if l.relocVariant == nil {
2405 l.relocVariant = make(map[relocId]sym.RelocVariant)
2408 l.relocVariant[relocId{s, ri}] = v
2410 delete(l.relocVariant, relocId{s, ri})
2414 // RelocVariant returns the 'variant' property of a relocation on
2415 // some specific symbol.
2416 func (l *Loader) RelocVariant(s Sym, ri int) sym.RelocVariant {
2417 return l.relocVariant[relocId{s, ri}]
2420 // UndefinedRelocTargets iterates through the global symbol index
2421 // space, looking for symbols with relocations targeting undefined
2422 // references. The linker's loadlib method uses this to determine if
2423 // there are unresolved references to functions in system libraries
2424 // (for example, libgcc.a), presumably due to CGO code. Return
2425 // value is a list of loader.Sym's corresponding to the undefined
2426 // cross-refs. The "limit" param controls the maximum number of
2427 // results returned; if "limit" is -1, then all undefs are returned.
2428 func (l *Loader) UndefinedRelocTargets(limit int) []Sym {
2430 for si := Sym(1); si < Sym(len(l.objSyms)); si++ {
2431 relocs := l.Relocs(si)
2432 for ri := 0; ri < relocs.Count(); ri++ {
2435 if rs != 0 && l.SymType(rs) == sym.SXREF && l.RawSymName(rs) != ".got" {
2436 result = append(result, rs)
2437 if limit != -1 && len(result) >= limit {
2446 // AssignTextSymbolOrder populates the Textp slices within each
2447 // library and compilation unit, insuring that packages are laid down
2448 // in dependency order (internal first, then everything else). Return value
2449 // is a slice of all text syms.
2450 func (l *Loader) AssignTextSymbolOrder(libs []*sym.Library, intlibs []bool, extsyms []Sym) []Sym {
2452 // Library Textp lists should be empty at this point.
2453 for _, lib := range libs {
2454 if len(lib.Textp) != 0 {
2455 panic("expected empty Textp slice for library")
2457 if len(lib.DupTextSyms) != 0 {
2458 panic("expected empty DupTextSyms slice for library")
2462 // Used to record which dupok symbol we've assigned to a unit.
2463 // Can't use the onlist attribute here because it will need to
2464 // clear for the later assignment of the sym.Symbol to a unit.
2465 // NB: we can convert to using onList once we no longer have to
2466 // call the regular addToTextp.
2467 assignedToUnit := MakeBitmap(l.NSym() + 1)
2469 // Start off textp with reachable external syms.
2471 for _, sym := range extsyms {
2472 if !l.attrReachable.Has(sym) {
2475 textp = append(textp, sym)
2478 // Walk through all text symbols from Go object files and append
2479 // them to their corresponding library's textp list.
2480 for _, o := range l.objs[goObjStart:] {
2483 for i, n := uint32(0), uint32(r.NAlldef()); i < n; i++ {
2484 gi := l.toGlobal(r, i)
2485 if !l.attrReachable.Has(gi) {
2489 st := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
2490 if st != sym.STEXT {
2493 dupok := osym.Dupok()
2494 if r2, i2 := l.toLocal(gi); r2 != r || i2 != i {
2495 // A dupok text symbol is resolved to another package.
2496 // We still need to record its presence in the current
2497 // package, as the trampoline pass expects packages
2498 // are laid out in dependency order.
2499 lib.DupTextSyms = append(lib.DupTextSyms, sym.LoaderSym(gi))
2500 continue // symbol in different object
2503 lib.DupTextSyms = append(lib.DupTextSyms, sym.LoaderSym(gi))
2507 lib.Textp = append(lib.Textp, sym.LoaderSym(gi))
2511 // Now assemble global textp, and assign text symbols to units.
2512 for _, doInternal := range [2]bool{true, false} {
2513 for idx, lib := range libs {
2514 if intlibs[idx] != doInternal {
2517 lists := [2][]sym.LoaderSym{lib.Textp, lib.DupTextSyms}
2518 for i, list := range lists {
2519 for _, s := range list {
2521 if !assignedToUnit.Has(sym) {
2522 textp = append(textp, sym)
2523 unit := l.SymUnit(sym)
2525 unit.Textp = append(unit.Textp, s)
2526 assignedToUnit.Set(sym)
2528 // Dupok symbols may be defined in multiple packages; the
2529 // associated package for a dupok sym is chosen sort of
2530 // arbitrarily (the first containing package that the linker
2531 // loads). Canonicalizes its Pkg to the package with which
2532 // it will be laid down in text.
2533 if i == 1 /* DupTextSyms2 */ && l.SymPkg(sym) != lib.Pkg {
2534 l.SetSymPkg(sym, lib.Pkg)
2540 lib.DupTextSyms = nil
2547 // ErrorReporter is a helper class for reporting errors.
2548 type ErrorReporter struct {
2550 AfterErrorAction func()
2553 // Errorf method logs an error message.
2555 // After each error, the error actions function will be invoked; this
2556 // will either terminate the link immediately (if -h option given)
2557 // or it will keep a count and exit if more than 20 errors have been printed.
2559 // Logging an error means that on exit cmd/link will delete any
2560 // output file and return a non-zero error code.
2561 func (reporter *ErrorReporter) Errorf(s Sym, format string, args ...interface{}) {
2562 if s != 0 && reporter.ldr.SymName(s) != "" {
2563 // Note: Replace is needed here because symbol names might have % in them,
2564 // due to the use of LinkString for names of instantiating types.
2565 format = strings.Replace(reporter.ldr.SymName(s), "%", "%%", -1) + ": " + format
2567 format = fmt.Sprintf("sym %d: %s", s, format)
2570 fmt.Fprintf(os.Stderr, format, args...)
2571 reporter.AfterErrorAction()
2574 // GetErrorReporter returns the loader's associated error reporter.
2575 func (l *Loader) GetErrorReporter() *ErrorReporter {
2576 return l.errorReporter
2579 // Errorf method logs an error message. See ErrorReporter.Errorf for details.
2580 func (l *Loader) Errorf(s Sym, format string, args ...interface{}) {
2581 l.errorReporter.Errorf(s, format, args...)
2584 // Symbol statistics.
2585 func (l *Loader) Stat() string {
2586 s := fmt.Sprintf("%d symbols, %d reachable\n", l.NSym(), l.NReachableSym())
2587 s += fmt.Sprintf("\t%d package symbols, %d hashed symbols, %d non-package symbols, %d external symbols\n",
2588 l.npkgsyms, l.nhashedsyms, int(l.extStart)-l.npkgsyms-l.nhashedsyms, l.NSym()-int(l.extStart))
2593 func (l *Loader) Dump() {
2595 for _, obj := range l.objs[goObjStart:] {
2597 fmt.Println(obj.i, obj.r.unit.Lib)
2600 fmt.Println("extStart:", l.extStart)
2601 fmt.Println("Nsyms:", len(l.objSyms))
2603 for i := Sym(1); i < Sym(len(l.objSyms)); i++ {
2605 if l.IsExternal(i) {
2606 pi = fmt.Sprintf("<ext %d>", l.extIndex(i))
2609 if l.SymSect(i) != nil {
2610 sect = l.SymSect(i).Name
2612 fmt.Printf("%v %v %v %v %x %v\n", i, l.SymName(i), l.SymType(i), pi, l.SymValue(i), sect)
2614 fmt.Println("symsByName")
2615 for name, i := range l.symsByName[0] {
2616 fmt.Println(i, name, 0)
2618 for name, i := range l.symsByName[1] {
2619 fmt.Println(i, name, 1)
2621 fmt.Println("payloads:")
2622 for i := range l.payloads {
2624 fmt.Println(i, pp.name, pp.ver, pp.kind)