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 hasUnknownPkgPath bool // if any Go object has unknown package path
266 strictDupMsgs int // number of strict-dup warning/errors, when FlagStrictDups is enabled
268 elfsetstring elfsetstringFunc
270 errorReporter *ErrorReporter
272 npkgsyms int // number of package symbols, for accounting
273 nhashedsyms int // number of hashed symbols, for accounting
291 type elfsetstringFunc func(str string, off int)
293 // extSymPayload holds the payload (data + relocations) for linker-synthesized
294 // external symbols (note that symbol value is stored in a separate slice).
295 type extSymPayload struct {
296 name string // TODO: would this be better as offset into str table?
300 objidx uint32 // index of original object if sym made by cloneToExternal
308 FlagStrictDups = 1 << iota
311 func NewLoader(flags uint32, elfsetstring elfsetstringFunc, reporter *ErrorReporter) *Loader {
312 nbuiltin := goobj.NBuiltin()
313 extReader := &oReader{objidx: extObj}
315 start: make(map[*oReader]Sym),
316 objs: []objIdx{{}, {extReader, 0}}, // reserve index 0 for nil symbol, 1 for external symbols
317 objSyms: make([]objSym, 1, 1), // This will get overwritten later.
318 extReader: extReader,
319 symsByName: [2]map[string]Sym{make(map[string]Sym, 80000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
320 objByPkg: make(map[string]uint32),
321 outer: make(map[Sym]Sym),
322 sub: make(map[Sym]Sym),
323 dynimplib: make(map[Sym]string),
324 dynimpvers: make(map[Sym]string),
325 localentry: make(map[Sym]uint8),
326 extname: make(map[Sym]string),
327 attrReadOnly: make(map[Sym]bool),
328 elfType: make(map[Sym]elf.SymType),
329 elfSym: make(map[Sym]int32),
330 localElfSym: make(map[Sym]int32),
331 symPkg: make(map[Sym]string),
332 plt: make(map[Sym]int32),
333 got: make(map[Sym]int32),
334 dynid: make(map[Sym]int32),
335 attrSpecial: make(map[Sym]struct{}),
336 attrCgoExportDynamic: make(map[Sym]struct{}),
337 attrCgoExportStatic: make(map[Sym]struct{}),
338 generatedSyms: make(map[Sym]struct{}),
339 deferReturnTramp: make(map[Sym]bool),
340 extStaticSyms: make(map[nameVer]Sym),
341 builtinSyms: make([]Sym, nbuiltin),
343 elfsetstring: elfsetstring,
344 errorReporter: reporter,
345 sects: []*sym.Section{nil}, // reserve index 0 for nil section
351 // Add object file r, return the start index.
352 func (l *Loader) addObj(pkg string, r *oReader) Sym {
353 if _, ok := l.start[r]; ok {
354 panic("already added")
356 pkg = objabi.PathToPrefix(pkg) // the object file contains escaped package path
357 if _, ok := l.objByPkg[pkg]; !ok {
358 l.objByPkg[pkg] = r.objidx
360 i := Sym(len(l.objSyms))
362 l.objs = append(l.objs, objIdx{r, i})
363 if r.NeedNameExpansion() && !r.FromAssembly() {
364 l.hasUnknownPkgPath = true
369 // Add a symbol from an object file, return the global index.
370 // If the symbol already exist, it returns the index of that symbol.
371 func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj.Sym) Sym {
374 panic("addSym called after external symbol is created")
376 i := Sym(len(l.objSyms))
377 addToGlobal := func() {
378 l.objSyms = append(l.objSyms, objSym{r.objidx, li})
380 if name == "" && kind != hashed64Def && kind != hashedDef {
382 return i // unnamed aux symbol
384 if ver == r.version {
385 // Static symbol. Add its global index but don't
386 // add to name lookup table, as it cannot be
387 // referenced by name.
393 // Defined package symbols cannot be dup to each other.
394 // We load all the package symbols first, so we don't need
395 // to check dup here.
396 // We still add it to the lookup table, as it may still be
397 // referenced by name (e.g. through linkname).
398 l.symsByName[ver][name] = i
401 case hashed64Def, hashedDef:
402 // Hashed (content-addressable) symbol. Check the hash
403 // but don't add to name lookup table, as they are not
404 // referenced by name. Also no need to do overwriting
405 // check, as same hash indicates same content.
406 var checkHash func() (symAndSize, bool)
407 var addToHashMap func(symAndSize)
408 var h64 uint64 // only used for hashed64Def
409 var h *goobj.HashType // only used for hashedDef
410 if kind == hashed64Def {
411 checkHash = func() (symAndSize, bool) {
412 h64 = r.Hash64(li - uint32(r.ndef))
413 s, existed := st.hashed64Syms[h64]
416 addToHashMap = func(ss symAndSize) { st.hashed64Syms[h64] = ss }
418 checkHash = func() (symAndSize, bool) {
419 h = r.Hash(li - uint32(r.ndef+r.nhashed64def))
420 s, existed := st.hashedSyms[*h]
423 addToHashMap = func(ss symAndSize) { st.hashedSyms[*h] = ss }
426 if s, existed := checkHash(); existed {
427 // The content hash is built from symbol data and relocations. In the
428 // object file, the symbol data may not always contain trailing zeros,
429 // e.g. for [5]int{1,2,3} and [100]int{1,2,3}, the data is same
430 // (although the size is different).
431 // Also, for short symbols, the content hash is the identity function of
432 // the 8 bytes, and trailing zeros doesn't change the hash value, e.g.
433 // hash("A") == hash("A\0\0\0").
434 // So when two symbols have the same hash, we need to use the one with
437 // New symbol has larger size, use the new one. Rewrite the index mapping.
438 l.objSyms[s.sym] = objSym{r.objidx, li}
439 addToHashMap(symAndSize{s.sym, siz})
443 addToHashMap(symAndSize{i, siz})
448 // Non-package (named) symbol. Check if it already exists.
449 oldi, existed := l.symsByName[ver][name]
451 l.symsByName[ver][name] = i
455 // symbol already exists
457 if l.flags&FlagStrictDups != 0 {
458 l.checkdup(name, r, li, oldi)
460 // Fix for issue #47185 -- given two dupok symbols with
461 // different sizes, favor symbol with larger size. See
462 // also issue #46653.
463 szdup := l.SymSize(oldi)
464 sz := int64(r.Sym(li).Siz())
466 // new symbol overwrites old symbol.
467 l.objSyms[oldi] = objSym{r.objidx, li}
471 oldr, oldli := l.toLocal(oldi)
472 oldsym := oldr.Sym(oldli)
476 overwrite := r.DataSize(li) != 0
478 // new symbol overwrites old symbol.
479 oldtyp := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
480 if !(oldtyp.IsData() && oldr.DataSize(oldli) == 0) {
481 log.Fatalf("duplicated definition of symbol %s, from %s and %s", name, r.unit.Lib.Pkg, oldr.unit.Lib.Pkg)
483 l.objSyms[oldi] = objSym{r.objidx, li}
485 // old symbol overwrites new symbol.
486 typ := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
487 if !typ.IsData() { // only allow overwriting data symbol
488 log.Fatalf("duplicated definition of symbol %s, from %s and %s", name, r.unit.Lib.Pkg, oldr.unit.Lib.Pkg)
494 // newExtSym creates a new external sym with the specified
496 func (l *Loader) newExtSym(name string, ver int) Sym {
497 i := Sym(len(l.objSyms))
501 l.growValues(int(i) + 1)
502 l.growAttrBitmaps(int(i) + 1)
503 pi := l.newPayload(name, ver)
504 l.objSyms = append(l.objSyms, objSym{l.extReader.objidx, uint32(pi)})
505 l.extReader.syms = append(l.extReader.syms, i)
509 // LookupOrCreateSym looks up the symbol with the specified name/version,
510 // returning its Sym index if found. If the lookup fails, a new external
511 // Sym will be created, entered into the lookup tables, and returned.
512 func (l *Loader) LookupOrCreateSym(name string, ver int) Sym {
513 i := l.Lookup(name, ver)
517 i = l.newExtSym(name, ver)
518 static := ver >= sym.SymVerStatic || ver < 0
520 l.extStaticSyms[nameVer{name, ver}] = i
522 l.symsByName[ver][name] = i
527 // AddCgoExport records a cgo-exported symbol in l.CgoExports.
528 // This table is used to identify the correct Go symbol ABI to use
529 // to resolve references from host objects (which don't have ABIs).
530 func (l *Loader) AddCgoExport(s Sym) {
531 if l.CgoExports == nil {
532 l.CgoExports = make(map[string]Sym)
534 l.CgoExports[l.SymName(s)] = s
537 // LookupOrCreateCgoExport is like LookupOrCreateSym, but if ver
538 // indicates a global symbol, it uses the CgoExport table to determine
539 // the appropriate symbol version (ABI) to use. ver must be either 0
540 // or a static symbol version.
541 func (l *Loader) LookupOrCreateCgoExport(name string, ver int) Sym {
542 if ver >= sym.SymVerStatic {
543 return l.LookupOrCreateSym(name, ver)
546 panic("ver must be 0 or a static version")
548 // Look for a cgo-exported symbol from Go.
549 if s, ok := l.CgoExports[name]; ok {
552 // Otherwise, this must just be a symbol in the host object.
553 // Create a version 0 symbol for it.
554 return l.LookupOrCreateSym(name, 0)
557 func (l *Loader) IsExternal(i Sym) bool {
559 return l.isExtReader(r)
562 func (l *Loader) isExtReader(r *oReader) bool {
563 return r == l.extReader
566 // For external symbol, return its index in the payloads array.
567 // XXX result is actually not a global index. We (ab)use the Sym type
568 // so we don't need conversion for accessing bitmaps.
569 func (l *Loader) extIndex(i Sym) Sym {
570 _, li := l.toLocal(i)
574 // Get a new payload for external symbol, return its index in
575 // the payloads array.
576 func (l *Loader) newPayload(name string, ver int) int {
577 pi := len(l.payloads)
578 pp := l.allocPayload()
581 l.payloads = append(l.payloads, pp)
582 l.growExtAttrBitmaps()
586 // getPayload returns a pointer to the extSymPayload struct for an
587 // external symbol if the symbol has a payload. Will panic if the
588 // symbol in question is bogus (zero or not an external sym).
589 func (l *Loader) getPayload(i Sym) *extSymPayload {
590 if !l.IsExternal(i) {
591 panic(fmt.Sprintf("bogus symbol index %d in getPayload", i))
594 return l.payloads[pi]
597 // allocPayload allocates a new payload.
598 func (l *Loader) allocPayload() *extSymPayload {
599 batch := l.payloadBatch
601 batch = make([]extSymPayload, 1000)
604 l.payloadBatch = batch[1:]
608 func (ms *extSymPayload) Grow(siz int64) {
609 if int64(int(siz)) != siz {
610 log.Fatalf("symgrow size %d too long", siz)
612 if int64(len(ms.data)) >= siz {
615 if cap(ms.data) < int(siz) {
617 ms.data = append(ms.data, make([]byte, int(siz)+1-cl)...)
618 ms.data = ms.data[0:cl]
620 ms.data = ms.data[:siz]
623 // Convert a local index to a global index.
624 func (l *Loader) toGlobal(r *oReader, i uint32) Sym {
628 // Convert a global index to a local index.
629 func (l *Loader) toLocal(i Sym) (*oReader, uint32) {
630 return l.objs[l.objSyms[i].objidx].r, l.objSyms[i].s
633 // Resolve a local symbol reference. Return global index.
634 func (l *Loader) resolve(r *oReader, s goobj.SymRef) Sym {
636 switch p := s.PkgIdx; p {
637 case goobj.PkgIdxInvalid:
638 // {0, X} with non-zero X is never a valid sym reference from a Go object.
639 // We steal this space for symbol references from external objects.
640 // In this case, X is just the global index.
641 if l.isExtReader(r) {
648 case goobj.PkgIdxHashed64:
649 i := int(s.SymIdx) + r.ndef
651 case goobj.PkgIdxHashed:
652 i := int(s.SymIdx) + r.ndef + r.nhashed64def
654 case goobj.PkgIdxNone:
655 i := int(s.SymIdx) + r.ndef + r.nhashed64def + r.nhasheddef
657 case goobj.PkgIdxBuiltin:
658 if bi := l.builtinSyms[s.SymIdx]; bi != 0 {
661 l.reportMissingBuiltin(int(s.SymIdx), r.unit.Lib.Pkg)
663 case goobj.PkgIdxSelf:
666 rr = l.objs[r.pkg[p]].r
668 return l.toGlobal(rr, s.SymIdx)
671 // reportMissingBuiltin issues an error in the case where we have a
672 // relocation against a runtime builtin whose definition is not found
673 // when the runtime package is built. The canonical example is
674 // "runtime.racefuncenter" -- currently if you do something like
676 // go build -gcflags=-race myprogram.go
678 // the compiler will insert calls to the builtin runtime.racefuncenter,
679 // but the version of the runtime used for linkage won't actually contain
680 // definitions of that symbol. See issue #42396 for details.
682 // As currently implemented, this is a fatal error. This has drawbacks
683 // in that if there are multiple missing builtins, the error will only
684 // cite the first one. On the plus side, terminating the link here has
685 // advantages in that we won't run the risk of panics or crashes later
686 // on in the linker due to R_CALL relocations with 0-valued target
688 func (l *Loader) reportMissingBuiltin(bsym int, reflib string) {
689 bname, _ := goobj.BuiltinName(bsym)
690 log.Fatalf("reference to undefined builtin %q from package %q",
694 // Look up a symbol by name, return global index, or 0 if not found.
695 // This is more like Syms.ROLookup than Lookup -- it doesn't create
697 func (l *Loader) Lookup(name string, ver int) Sym {
698 if ver >= sym.SymVerStatic || ver < 0 {
699 return l.extStaticSyms[nameVer{name, ver}]
701 return l.symsByName[ver][name]
704 // Check that duplicate symbols have same contents.
705 func (l *Loader) checkdup(name string, r *oReader, li uint32, dup Sym) {
707 rdup, ldup := l.toLocal(dup)
708 pdup := rdup.Data(ldup)
709 reason := "same length but different contents"
710 if len(p) != len(pdup) {
711 reason = fmt.Sprintf("new length %d != old length %d", len(p), len(pdup))
712 } else if bytes.Equal(p, pdup) {
713 // For BSS symbols, we need to check size as well, see issue 46653.
714 szdup := l.SymSize(dup)
715 sz := int64(r.Sym(li).Siz())
719 reason = fmt.Sprintf("different sizes: new size %d != old size %d",
722 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)
724 // For the moment, allow DWARF subprogram DIEs for
725 // auto-generated wrapper functions. What seems to happen
726 // here is that we get different line numbers on formal
727 // params; I am guessing that the pos is being inherited
728 // from the spot where the wrapper is needed.
729 allowed := strings.HasPrefix(name, "go.info.go.interface") ||
730 strings.HasPrefix(name, "go.info.go.builtin") ||
731 strings.HasPrefix(name, "go.debuglines")
737 func (l *Loader) NStrictDupMsgs() int { return l.strictDupMsgs }
739 // Number of total symbols.
740 func (l *Loader) NSym() int {
741 return len(l.objSyms)
744 // Number of defined Go symbols.
745 func (l *Loader) NDef() int {
746 return int(l.extStart)
749 // Number of reachable symbols.
750 func (l *Loader) NReachableSym() int {
751 return l.attrReachable.Count()
754 // Returns the raw (unpatched) name of the i-th symbol.
755 func (l *Loader) RawSymName(i Sym) string {
757 pp := l.getPayload(i)
760 r, li := l.toLocal(i)
761 return r.Sym(li).Name(r.Reader)
764 // Returns the (patched) name of the i-th symbol.
765 func (l *Loader) SymName(i Sym) string {
767 pp := l.getPayload(i)
770 r, li := l.toLocal(i)
774 name := r.Sym(li).Name(r.Reader)
775 if !r.NeedNameExpansion() {
778 return strings.Replace(name, "\"\".", r.pkgprefix, -1)
781 // Returns the version of the i-th symbol.
782 func (l *Loader) SymVersion(i Sym) int {
784 pp := l.getPayload(i)
787 r, li := l.toLocal(i)
788 return int(abiToVer(r.Sym(li).ABI(), r.version))
791 func (l *Loader) IsFileLocal(i Sym) bool {
792 return l.SymVersion(i) >= sym.SymVerStatic
795 // IsFromAssembly returns true if this symbol is derived from an
796 // object file generated by the Go assembler.
797 func (l *Loader) IsFromAssembly(i Sym) bool {
802 return r.FromAssembly()
805 // Returns the type of the i-th symbol.
806 func (l *Loader) SymType(i Sym) sym.SymKind {
808 pp := l.getPayload(i)
814 r, li := l.toLocal(i)
815 return sym.AbiSymKindToSymKind[objabi.SymKind(r.Sym(li).Type())]
818 // Returns the attributes of the i-th symbol.
819 func (l *Loader) SymAttr(i Sym) uint8 {
821 // TODO: do something? External symbols have different representation of attributes.
822 // For now, ReflectMethod, NoSplit, GoType, and Typelink are used and they cannot be
823 // set by external symbol.
826 r, li := l.toLocal(i)
827 return r.Sym(li).Flag()
830 // Returns the size of the i-th symbol.
831 func (l *Loader) SymSize(i Sym) int64 {
833 pp := l.getPayload(i)
836 r, li := l.toLocal(i)
837 return int64(r.Sym(li).Siz())
840 // AttrReachable returns true for symbols that are transitively
841 // referenced from the entry points. Unreachable symbols are not
842 // written to the output.
843 func (l *Loader) AttrReachable(i Sym) bool {
844 return l.attrReachable.Has(i)
847 // SetAttrReachable sets the reachability property for a symbol (see
849 func (l *Loader) SetAttrReachable(i Sym, v bool) {
851 l.attrReachable.Set(i)
853 l.attrReachable.Unset(i)
857 // AttrOnList returns true for symbols that are on some list (such as
858 // the list of all text symbols, or one of the lists of data symbols)
859 // and is consulted to avoid bugs where a symbol is put on a list
861 func (l *Loader) AttrOnList(i Sym) bool {
862 return l.attrOnList.Has(i)
865 // SetAttrOnList sets the "on list" property for a symbol (see
867 func (l *Loader) SetAttrOnList(i Sym, v bool) {
871 l.attrOnList.Unset(i)
875 // AttrLocal returns true for symbols that are only visible within the
876 // module (executable or shared library) being linked. This attribute
877 // is applied to thunks and certain other linker-generated symbols.
878 func (l *Loader) AttrLocal(i Sym) bool {
879 return l.attrLocal.Has(i)
882 // SetAttrLocal the "local" property for a symbol (see AttrLocal above).
883 func (l *Loader) SetAttrLocal(i Sym, v bool) {
891 // AttrUsedInIface returns true for a type symbol that is used in
893 func (l *Loader) AttrUsedInIface(i Sym) bool {
894 return l.attrUsedInIface.Has(i)
897 func (l *Loader) SetAttrUsedInIface(i Sym, v bool) {
899 l.attrUsedInIface.Set(i)
901 l.attrUsedInIface.Unset(i)
905 // SymAddr checks that a symbol is reachable, and returns its value.
906 func (l *Loader) SymAddr(i Sym) int64 {
907 if !l.AttrReachable(i) {
908 panic("unreachable symbol in symaddr")
913 // AttrNotInSymbolTable returns true for symbols that should not be
914 // added to the symbol table of the final generated load module.
915 func (l *Loader) AttrNotInSymbolTable(i Sym) bool {
916 return l.attrNotInSymbolTable.Has(i)
919 // SetAttrNotInSymbolTable the "not in symtab" property for a symbol
920 // (see AttrNotInSymbolTable above).
921 func (l *Loader) SetAttrNotInSymbolTable(i Sym, v bool) {
923 l.attrNotInSymbolTable.Set(i)
925 l.attrNotInSymbolTable.Unset(i)
929 // AttrVisibilityHidden symbols returns true for ELF symbols with
930 // visibility set to STV_HIDDEN. They become local symbols in
931 // the final executable. Only relevant when internally linking
932 // on an ELF platform.
933 func (l *Loader) AttrVisibilityHidden(i Sym) bool {
934 if !l.IsExternal(i) {
937 return l.attrVisibilityHidden.Has(l.extIndex(i))
940 // SetAttrVisibilityHidden sets the "hidden visibility" property for a
941 // symbol (see AttrVisibilityHidden).
942 func (l *Loader) SetAttrVisibilityHidden(i Sym, v bool) {
943 if !l.IsExternal(i) {
944 panic("tried to set visibility attr on non-external symbol")
947 l.attrVisibilityHidden.Set(l.extIndex(i))
949 l.attrVisibilityHidden.Unset(l.extIndex(i))
953 // AttrDuplicateOK returns true for a symbol that can be present in
954 // multiple object files.
955 func (l *Loader) AttrDuplicateOK(i Sym) bool {
956 if !l.IsExternal(i) {
957 // TODO: if this path winds up being taken frequently, it
958 // might make more sense to copy the flag value out of the object
959 // into a larger bitmap during preload.
960 r, li := l.toLocal(i)
961 return r.Sym(li).Dupok()
963 return l.attrDuplicateOK.Has(l.extIndex(i))
966 // SetAttrDuplicateOK sets the "duplicate OK" property for an external
967 // symbol (see AttrDuplicateOK).
968 func (l *Loader) SetAttrDuplicateOK(i Sym, v bool) {
969 if !l.IsExternal(i) {
970 panic("tried to set dupok attr on non-external symbol")
973 l.attrDuplicateOK.Set(l.extIndex(i))
975 l.attrDuplicateOK.Unset(l.extIndex(i))
979 // AttrShared returns true for symbols compiled with the -shared option.
980 func (l *Loader) AttrShared(i Sym) bool {
981 if !l.IsExternal(i) {
982 // TODO: if this path winds up being taken frequently, it
983 // might make more sense to copy the flag value out of the
984 // object into a larger bitmap during preload.
988 return l.attrShared.Has(l.extIndex(i))
991 // SetAttrShared sets the "shared" property for an external
992 // symbol (see AttrShared).
993 func (l *Loader) SetAttrShared(i Sym, v bool) {
994 if !l.IsExternal(i) {
995 panic(fmt.Sprintf("tried to set shared attr on non-external symbol %d %s", i, l.SymName(i)))
998 l.attrShared.Set(l.extIndex(i))
1000 l.attrShared.Unset(l.extIndex(i))
1004 // AttrExternal returns true for function symbols loaded from host
1006 func (l *Loader) AttrExternal(i Sym) bool {
1007 if !l.IsExternal(i) {
1010 return l.attrExternal.Has(l.extIndex(i))
1013 // SetAttrExternal sets the "external" property for an host object
1014 // symbol (see AttrExternal).
1015 func (l *Loader) SetAttrExternal(i Sym, v bool) {
1016 if !l.IsExternal(i) {
1017 panic(fmt.Sprintf("tried to set external attr on non-external symbol %q", l.RawSymName(i)))
1020 l.attrExternal.Set(l.extIndex(i))
1022 l.attrExternal.Unset(l.extIndex(i))
1026 // AttrSpecial returns true for a symbols that do not have their
1027 // address (i.e. Value) computed by the usual mechanism of
1028 // data.go:dodata() & data.go:address().
1029 func (l *Loader) AttrSpecial(i Sym) bool {
1030 _, ok := l.attrSpecial[i]
1034 // SetAttrSpecial sets the "special" property for a symbol (see
1036 func (l *Loader) SetAttrSpecial(i Sym, v bool) {
1038 l.attrSpecial[i] = struct{}{}
1040 delete(l.attrSpecial, i)
1044 // AttrCgoExportDynamic returns true for a symbol that has been
1045 // specially marked via the "cgo_export_dynamic" compiler directive
1046 // written by cgo (in response to //export directives in the source).
1047 func (l *Loader) AttrCgoExportDynamic(i Sym) bool {
1048 _, ok := l.attrCgoExportDynamic[i]
1052 // SetAttrCgoExportDynamic sets the "cgo_export_dynamic" for a symbol
1053 // (see AttrCgoExportDynamic).
1054 func (l *Loader) SetAttrCgoExportDynamic(i Sym, v bool) {
1056 l.attrCgoExportDynamic[i] = struct{}{}
1058 delete(l.attrCgoExportDynamic, i)
1062 // AttrCgoExportStatic returns true for a symbol that has been
1063 // specially marked via the "cgo_export_static" directive
1065 func (l *Loader) AttrCgoExportStatic(i Sym) bool {
1066 _, ok := l.attrCgoExportStatic[i]
1070 // SetAttrCgoExportStatic sets the "cgo_export_static" for a symbol
1071 // (see AttrCgoExportStatic).
1072 func (l *Loader) SetAttrCgoExportStatic(i Sym, v bool) {
1074 l.attrCgoExportStatic[i] = struct{}{}
1076 delete(l.attrCgoExportStatic, i)
1080 // IsGeneratedSym returns true if a symbol's been previously marked as a
1081 // generator symbol through the SetIsGeneratedSym. The functions for generator
1082 // symbols are kept in the Link context.
1083 func (l *Loader) IsGeneratedSym(i Sym) bool {
1084 _, ok := l.generatedSyms[i]
1088 // SetIsGeneratedSym marks symbols as generated symbols. Data shouldn't be
1089 // stored in generated symbols, and a function is registered and called for
1090 // each of these symbols.
1091 func (l *Loader) SetIsGeneratedSym(i Sym, v bool) {
1092 if !l.IsExternal(i) {
1093 panic("only external symbols can be generated")
1096 l.generatedSyms[i] = struct{}{}
1098 delete(l.generatedSyms, i)
1102 func (l *Loader) AttrCgoExport(i Sym) bool {
1103 return l.AttrCgoExportDynamic(i) || l.AttrCgoExportStatic(i)
1106 // AttrReadOnly returns true for a symbol whose underlying data
1107 // is stored via a read-only mmap.
1108 func (l *Loader) AttrReadOnly(i Sym) bool {
1109 if v, ok := l.attrReadOnly[i]; ok {
1112 if l.IsExternal(i) {
1113 pp := l.getPayload(i)
1115 return l.objs[pp.objidx].r.ReadOnly()
1119 r, _ := l.toLocal(i)
1123 // SetAttrReadOnly sets the "data is read only" property for a symbol
1124 // (see AttrReadOnly).
1125 func (l *Loader) SetAttrReadOnly(i Sym, v bool) {
1126 l.attrReadOnly[i] = v
1129 // AttrSubSymbol returns true for symbols that are listed as a
1130 // sub-symbol of some other outer symbol. The sub/outer mechanism is
1131 // used when loading host objects (sections from the host object
1132 // become regular linker symbols and symbols go on the Sub list of
1133 // their section) and for constructing the global offset table when
1134 // internally linking a dynamic executable.
1136 // Note that in later stages of the linker, we set Outer(S) to some
1137 // container symbol C, but don't set Sub(C). Thus we have two
1138 // distinct scenarios:
1140 // - Outer symbol covers the address ranges of its sub-symbols.
1141 // Outer.Sub is set in this case.
1142 // - Outer symbol doesn't conver the address ranges. It is zero-sized
1143 // and doesn't have sub-symbols. In the case, the inner symbol is
1144 // not actually a "SubSymbol". (Tricky!)
1146 // This method returns TRUE only for sub-symbols in the first scenario.
1148 // FIXME: would be better to do away with this and have a better way
1149 // to represent container symbols.
1151 func (l *Loader) AttrSubSymbol(i Sym) bool {
1152 // we don't explicitly store this attribute any more -- return
1153 // a value based on the sub-symbol setting.
1158 return l.SubSym(o) != 0
1161 // Note that we don't have a 'SetAttrSubSymbol' method in the loader;
1162 // clients should instead use the AddInteriorSym method to establish
1163 // containment relationships for host object symbols.
1165 // Returns whether the i-th symbol has ReflectMethod attribute set.
1166 func (l *Loader) IsReflectMethod(i Sym) bool {
1167 return l.SymAttr(i)&goobj.SymFlagReflectMethod != 0
1170 // Returns whether the i-th symbol is nosplit.
1171 func (l *Loader) IsNoSplit(i Sym) bool {
1172 return l.SymAttr(i)&goobj.SymFlagNoSplit != 0
1175 // Returns whether this is a Go type symbol.
1176 func (l *Loader) IsGoType(i Sym) bool {
1177 return l.SymAttr(i)&goobj.SymFlagGoType != 0
1180 // Returns whether this symbol should be included in typelink.
1181 func (l *Loader) IsTypelink(i Sym) bool {
1182 return l.SymAttr(i)&goobj.SymFlagTypelink != 0
1185 // Returns whether this symbol is an itab symbol.
1186 func (l *Loader) IsItab(i Sym) bool {
1187 if l.IsExternal(i) {
1190 r, li := l.toLocal(i)
1191 return r.Sym(li).IsItab()
1194 // Returns whether this symbol is a dictionary symbol.
1195 func (l *Loader) IsDict(i Sym) bool {
1196 if l.IsExternal(i) {
1199 r, li := l.toLocal(i)
1200 return r.Sym(li).IsDict()
1203 // Return whether this is a trampoline of a deferreturn call.
1204 func (l *Loader) IsDeferReturnTramp(i Sym) bool {
1205 return l.deferReturnTramp[i]
1208 // Set that i is a trampoline of a deferreturn call.
1209 func (l *Loader) SetIsDeferReturnTramp(i Sym, v bool) {
1210 l.deferReturnTramp[i] = v
1213 // growValues grows the slice used to store symbol values.
1214 func (l *Loader) growValues(reqLen int) {
1215 curLen := len(l.values)
1216 if reqLen > curLen {
1217 l.values = append(l.values, make([]int64, reqLen+1-curLen)...)
1221 // SymValue returns the value of the i-th symbol. i is global index.
1222 func (l *Loader) SymValue(i Sym) int64 {
1226 // SetSymValue sets the value of the i-th symbol. i is global index.
1227 func (l *Loader) SetSymValue(i Sym, val int64) {
1231 // AddToSymValue adds to the value of the i-th symbol. i is the global index.
1232 func (l *Loader) AddToSymValue(i Sym, val int64) {
1236 // Returns the symbol content of the i-th symbol. i is global index.
1237 func (l *Loader) Data(i Sym) []byte {
1238 if l.IsExternal(i) {
1239 pp := l.getPayload(i)
1245 r, li := l.toLocal(i)
1249 // FreeData clears the symbol data of an external symbol, allowing the memory
1250 // to be freed earlier. No-op for non-external symbols.
1251 // i is global index.
1252 func (l *Loader) FreeData(i Sym) {
1253 if l.IsExternal(i) {
1254 pp := l.getPayload(i)
1261 // SymAlign returns the alignment for a symbol.
1262 func (l *Loader) SymAlign(i Sym) int32 {
1263 if int(i) >= len(l.align) {
1264 // align is extended lazily -- it the sym in question is
1265 // outside the range of the existing slice, then we assume its
1266 // alignment has not yet been set.
1269 // TODO: would it make sense to return an arch-specific
1270 // alignment depending on section type? E.g. STEXT => 32,
1276 return int32(1 << (abits - 1))
1279 // SetSymAlign sets the alignment for a symbol.
1280 func (l *Loader) SetSymAlign(i Sym, align int32) {
1281 // Reject nonsense alignments.
1282 if align < 0 || align&(align-1) != 0 {
1283 panic("bad alignment value")
1285 if int(i) >= len(l.align) {
1286 l.align = append(l.align, make([]uint8, l.NSym()-len(l.align))...)
1291 l.align[i] = uint8(bits.Len32(uint32(align)))
1294 // SymValue returns the section of the i-th symbol. i is global index.
1295 func (l *Loader) SymSect(i Sym) *sym.Section {
1296 if int(i) >= len(l.symSects) {
1297 // symSects is extended lazily -- it the sym in question is
1298 // outside the range of the existing slice, then we assume its
1299 // section has not yet been set.
1302 return l.sects[l.symSects[i]]
1305 // SetSymSect sets the section of the i-th symbol. i is global index.
1306 func (l *Loader) SetSymSect(i Sym, sect *sym.Section) {
1307 if int(i) >= len(l.symSects) {
1308 l.symSects = append(l.symSects, make([]uint16, l.NSym()-len(l.symSects))...)
1310 l.symSects[i] = sect.Index
1313 // growSects grows the slice used to store symbol sections.
1314 func (l *Loader) growSects(reqLen int) {
1315 curLen := len(l.symSects)
1316 if reqLen > curLen {
1317 l.symSects = append(l.symSects, make([]uint16, reqLen+1-curLen)...)
1321 // NewSection creates a new (output) section.
1322 func (l *Loader) NewSection() *sym.Section {
1323 sect := new(sym.Section)
1325 if idx != int(uint16(idx)) {
1326 panic("too many sections created")
1328 sect.Index = uint16(idx)
1329 l.sects = append(l.sects, sect)
1333 // SymDynImplib returns the "dynimplib" attribute for the specified
1334 // symbol, making up a portion of the info for a symbol specified
1335 // on a "cgo_import_dynamic" compiler directive.
1336 func (l *Loader) SymDynimplib(i Sym) string {
1337 return l.dynimplib[i]
1340 // SetSymDynimplib sets the "dynimplib" attribute for a symbol.
1341 func (l *Loader) SetSymDynimplib(i Sym, value string) {
1342 // reject bad symbols
1343 if i >= Sym(len(l.objSyms)) || i == 0 {
1344 panic("bad symbol index in SetDynimplib")
1347 delete(l.dynimplib, i)
1349 l.dynimplib[i] = value
1353 // SymDynimpvers returns the "dynimpvers" attribute for the specified
1354 // symbol, making up a portion of the info for a symbol specified
1355 // on a "cgo_import_dynamic" compiler directive.
1356 func (l *Loader) SymDynimpvers(i Sym) string {
1357 return l.dynimpvers[i]
1360 // SetSymDynimpvers sets the "dynimpvers" attribute for a symbol.
1361 func (l *Loader) SetSymDynimpvers(i Sym, value string) {
1362 // reject bad symbols
1363 if i >= Sym(len(l.objSyms)) || i == 0 {
1364 panic("bad symbol index in SetDynimpvers")
1367 delete(l.dynimpvers, i)
1369 l.dynimpvers[i] = value
1373 // SymExtname returns the "extname" value for the specified
1375 func (l *Loader) SymExtname(i Sym) string {
1376 if s, ok := l.extname[i]; ok {
1382 // SetSymExtname sets the "extname" attribute for a symbol.
1383 func (l *Loader) SetSymExtname(i Sym, value string) {
1384 // reject bad symbols
1385 if i >= Sym(len(l.objSyms)) || i == 0 {
1386 panic("bad symbol index in SetExtname")
1389 delete(l.extname, i)
1391 l.extname[i] = value
1395 // SymElfType returns the previously recorded ELF type for a symbol
1396 // (used only for symbols read from shared libraries by ldshlibsyms).
1397 // It is not set for symbols defined by the packages being linked or
1398 // by symbols read by ldelf (and so is left as elf.STT_NOTYPE).
1399 func (l *Loader) SymElfType(i Sym) elf.SymType {
1400 if et, ok := l.elfType[i]; ok {
1403 return elf.STT_NOTYPE
1406 // SetSymElfType sets the elf type attribute for a symbol.
1407 func (l *Loader) SetSymElfType(i Sym, et elf.SymType) {
1408 // reject bad symbols
1409 if i >= Sym(len(l.objSyms)) || i == 0 {
1410 panic("bad symbol index in SetSymElfType")
1412 if et == elf.STT_NOTYPE {
1413 delete(l.elfType, i)
1419 // SymElfSym returns the ELF symbol index for a given loader
1420 // symbol, assigned during ELF symtab generation.
1421 func (l *Loader) SymElfSym(i Sym) int32 {
1425 // SetSymElfSym sets the elf symbol index for a symbol.
1426 func (l *Loader) SetSymElfSym(i Sym, es int32) {
1428 panic("bad sym index")
1437 // SymLocalElfSym returns the "local" ELF symbol index for a given loader
1438 // symbol, assigned during ELF symtab generation.
1439 func (l *Loader) SymLocalElfSym(i Sym) int32 {
1440 return l.localElfSym[i]
1443 // SetSymLocalElfSym sets the "local" elf symbol index for a symbol.
1444 func (l *Loader) SetSymLocalElfSym(i Sym, es int32) {
1446 panic("bad sym index")
1449 delete(l.localElfSym, i)
1451 l.localElfSym[i] = es
1455 // SymPlt returns the PLT offset of symbol s.
1456 func (l *Loader) SymPlt(s Sym) int32 {
1457 if v, ok := l.plt[s]; ok {
1463 // SetPlt sets the PLT offset of symbol i.
1464 func (l *Loader) SetPlt(i Sym, v int32) {
1465 if i >= Sym(len(l.objSyms)) || i == 0 {
1466 panic("bad symbol for SetPlt")
1475 // SymGot returns the GOT offset of symbol s.
1476 func (l *Loader) SymGot(s Sym) int32 {
1477 if v, ok := l.got[s]; ok {
1483 // SetGot sets the GOT offset of symbol i.
1484 func (l *Loader) SetGot(i Sym, v int32) {
1485 if i >= Sym(len(l.objSyms)) || i == 0 {
1486 panic("bad symbol for SetGot")
1495 // SymDynid returns the "dynid" property for the specified symbol.
1496 func (l *Loader) SymDynid(i Sym) int32 {
1497 if s, ok := l.dynid[i]; ok {
1503 // SetSymDynid sets the "dynid" property for a symbol.
1504 func (l *Loader) SetSymDynid(i Sym, val int32) {
1505 // reject bad symbols
1506 if i >= Sym(len(l.objSyms)) || i == 0 {
1507 panic("bad symbol index in SetSymDynid")
1516 // DynIdSyms returns the set of symbols for which dynID is set to an
1517 // interesting (non-default) value. This is expected to be a fairly
1519 func (l *Loader) DynidSyms() []Sym {
1520 sl := make([]Sym, 0, len(l.dynid))
1521 for s := range l.dynid {
1524 sort.Slice(sl, func(i, j int) bool { return sl[i] < sl[j] })
1528 // SymGoType returns the 'Gotype' property for a given symbol (set by
1529 // the Go compiler for variable symbols). This version relies on
1530 // reading aux symbols for the target sym -- it could be that a faster
1531 // approach would be to check for gotype during preload and copy the
1532 // results in to a map (might want to try this at some point and see
1533 // if it helps speed things up).
1534 func (l *Loader) SymGoType(i Sym) Sym { return l.aux1(i, goobj.AuxGotype) }
1536 // SymUnit returns the compilation unit for a given symbol (which will
1537 // typically be nil for external or linker-manufactured symbols).
1538 func (l *Loader) SymUnit(i Sym) *sym.CompilationUnit {
1539 if l.IsExternal(i) {
1540 pp := l.getPayload(i)
1542 r := l.objs[pp.objidx].r
1547 r, _ := l.toLocal(i)
1551 // SymPkg returns the package where the symbol came from (for
1552 // regular compiler-generated Go symbols), but in the case of
1553 // building with "-linkshared" (when a symbol is read from a
1554 // shared library), will hold the library name.
1555 // NOTE: this corresponds to sym.Symbol.File field.
1556 func (l *Loader) SymPkg(i Sym) string {
1557 if f, ok := l.symPkg[i]; ok {
1560 if l.IsExternal(i) {
1561 pp := l.getPayload(i)
1563 r := l.objs[pp.objidx].r
1564 return r.unit.Lib.Pkg
1568 r, _ := l.toLocal(i)
1569 return r.unit.Lib.Pkg
1572 // SetSymPkg sets the package/library for a symbol. This is
1573 // needed mainly for external symbols, specifically those imported
1574 // from shared libraries.
1575 func (l *Loader) SetSymPkg(i Sym, pkg string) {
1576 // reject bad symbols
1577 if i >= Sym(len(l.objSyms)) || i == 0 {
1578 panic("bad symbol index in SetSymPkg")
1583 // SymLocalentry returns the "local entry" value for the specified
1585 func (l *Loader) SymLocalentry(i Sym) uint8 {
1586 return l.localentry[i]
1589 // SetSymLocalentry sets the "local entry" attribute for a symbol.
1590 func (l *Loader) SetSymLocalentry(i Sym, value uint8) {
1591 // reject bad symbols
1592 if i >= Sym(len(l.objSyms)) || i == 0 {
1593 panic("bad symbol index in SetSymLocalentry")
1596 delete(l.localentry, i)
1598 l.localentry[i] = value
1602 // Returns the number of aux symbols given a global index.
1603 func (l *Loader) NAux(i Sym) int {
1604 if l.IsExternal(i) {
1607 r, li := l.toLocal(i)
1611 // Returns the "handle" to the j-th aux symbol of the i-th symbol.
1612 func (l *Loader) Aux(i Sym, j int) Aux {
1613 if l.IsExternal(i) {
1616 r, li := l.toLocal(i)
1617 if j >= r.NAux(li) {
1620 return Aux{r.Aux(li, j), r, l}
1623 // GetFuncDwarfAuxSyms collects and returns the auxiliary DWARF
1624 // symbols associated with a given function symbol. Prior to the
1625 // introduction of the loader, this was done purely using name
1626 // lookups, e.f. for function with name XYZ we would then look up
1627 // go.info.XYZ, etc.
1628 func (l *Loader) GetFuncDwarfAuxSyms(fnSymIdx Sym) (auxDwarfInfo, auxDwarfLoc, auxDwarfRanges, auxDwarfLines Sym) {
1629 if l.SymType(fnSymIdx) != sym.STEXT {
1630 log.Fatalf("error: non-function sym %d/%s t=%s passed to GetFuncDwarfAuxSyms", fnSymIdx, l.SymName(fnSymIdx), l.SymType(fnSymIdx).String())
1632 if l.IsExternal(fnSymIdx) {
1633 // Current expectation is that any external function will
1634 // not have auxsyms.
1637 r, li := l.toLocal(fnSymIdx)
1639 for i := range auxs {
1642 case goobj.AuxDwarfInfo:
1643 auxDwarfInfo = l.resolve(r, a.Sym())
1644 if l.SymType(auxDwarfInfo) != sym.SDWARFFCN {
1645 panic("aux dwarf info sym with wrong type")
1647 case goobj.AuxDwarfLoc:
1648 auxDwarfLoc = l.resolve(r, a.Sym())
1649 if l.SymType(auxDwarfLoc) != sym.SDWARFLOC {
1650 panic("aux dwarf loc sym with wrong type")
1652 case goobj.AuxDwarfRanges:
1653 auxDwarfRanges = l.resolve(r, a.Sym())
1654 if l.SymType(auxDwarfRanges) != sym.SDWARFRANGE {
1655 panic("aux dwarf ranges sym with wrong type")
1657 case goobj.AuxDwarfLines:
1658 auxDwarfLines = l.resolve(r, a.Sym())
1659 if l.SymType(auxDwarfLines) != sym.SDWARFLINES {
1660 panic("aux dwarf lines sym with wrong type")
1667 // AddInteriorSym sets up 'interior' as an interior symbol of
1668 // container/payload symbol 'container'. An interior symbol does not
1669 // itself have data, but gives a name to a subrange of the data in its
1670 // container symbol. The container itself may or may not have a name.
1671 // This method is intended primarily for use in the host object
1672 // loaders, to capture the semantics of symbols and sections in an
1673 // object file. When reading a host object file, we'll typically
1674 // encounter a static section symbol (ex: ".text") containing content
1675 // for a collection of functions, then a series of ELF (or macho, etc)
1676 // symbol table entries each of which points into a sub-section
1677 // (offset and length) of its corresponding container symbol. Within
1678 // the go linker we create a loader.Sym for the container (which is
1679 // expected to have the actual content/payload) and then a set of
1680 // interior loader.Sym's that point into a portion of the container.
1681 func (l *Loader) AddInteriorSym(container Sym, interior Sym) {
1682 // Container symbols are expected to have content/data.
1683 // NB: this restriction may turn out to be too strict (it's possible
1684 // to imagine a zero-sized container with an interior symbol pointing
1685 // into it); it's ok to relax or remove it if we counter an
1686 // oddball host object that triggers this.
1687 if l.SymSize(container) == 0 && len(l.Data(container)) == 0 {
1688 panic("unexpected empty container symbol")
1690 // The interior symbols for a container are not expected to have
1691 // content/data or relocations.
1692 if len(l.Data(interior)) != 0 {
1693 panic("unexpected non-empty interior symbol")
1695 // Interior symbol is expected to be in the symbol table.
1696 if l.AttrNotInSymbolTable(interior) {
1697 panic("interior symbol must be in symtab")
1699 // Only a single level of containment is allowed.
1700 if l.OuterSym(container) != 0 {
1701 panic("outer has outer itself")
1703 // Interior sym should not already have a sibling.
1704 if l.SubSym(interior) != 0 {
1705 panic("sub set for subsym")
1707 // Interior sym should not already point at a container.
1708 if l.OuterSym(interior) != 0 {
1709 panic("outer already set for subsym")
1711 l.sub[interior] = l.sub[container]
1712 l.sub[container] = interior
1713 l.outer[interior] = container
1716 // OuterSym gets the outer symbol for host object loaded symbols.
1717 func (l *Loader) OuterSym(i Sym) Sym {
1718 // FIXME: add check for isExternal?
1722 // SubSym gets the subsymbol for host object loaded symbols.
1723 func (l *Loader) SubSym(i Sym) Sym {
1724 // NB: note -- no check for l.isExternal(), since I am pretty sure
1725 // that later phases in the linker set subsym for "type." syms
1729 // SetCarrierSym declares that 'c' is the carrier or container symbol
1730 // for 's'. Carrier symbols are used in the linker to as a container
1731 // for a collection of sub-symbols where the content of the
1732 // sub-symbols is effectively concatenated to form the content of the
1733 // carrier. The carrier is given a name in the output symbol table
1734 // while the sub-symbol names are not. For example, the Go compiler
1735 // emits named string symbols (type SGOSTRING) when compiling a
1736 // package; after being deduplicated, these symbols are collected into
1737 // a single unit by assigning them a new carrier symbol named
1738 // "go.string.*" (which appears in the final symbol table for the
1739 // output load module).
1740 func (l *Loader) SetCarrierSym(s Sym, c Sym) {
1742 panic("invalid carrier in SetCarrierSym")
1745 panic("invalid sub-symbol in SetCarrierSym")
1747 // Carrier symbols are not expected to have content/data. It is
1748 // ok for them to have non-zero size (to allow for use of generator
1750 if len(l.Data(c)) != 0 {
1751 panic("unexpected non-empty carrier symbol")
1754 // relocsym's foldSubSymbolOffset requires that we only
1755 // have a single level of containment-- enforce here.
1756 if l.outer[c] != 0 {
1757 panic("invalid nested carrier sym")
1761 // Initialize Reachable bitmap and its siblings for running deadcode pass.
1762 func (l *Loader) InitReachable() {
1763 l.growAttrBitmaps(l.NSym() + 1)
1766 type symWithVal struct {
1770 type bySymValue []symWithVal
1772 func (s bySymValue) Len() int { return len(s) }
1773 func (s bySymValue) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
1774 func (s bySymValue) Less(i, j int) bool { return s[i].v < s[j].v }
1776 // SortSub walks through the sub-symbols for 's' and sorts them
1777 // in place by increasing value. Return value is the new
1778 // sub symbol for the specified outer symbol.
1779 func (l *Loader) SortSub(s Sym) Sym {
1781 if s == 0 || l.sub[s] == 0 {
1785 // Sort symbols using a slice first. Use a stable sort on the off
1786 // chance that there's more than once symbol with the same value,
1787 // so as to preserve reproducible builds.
1788 sl := []symWithVal{}
1789 for ss := l.sub[s]; ss != 0; ss = l.sub[ss] {
1790 sl = append(sl, symWithVal{s: ss, v: l.SymValue(ss)})
1792 sort.Stable(bySymValue(sl))
1794 // Then apply any changes needed to the sub map.
1796 for i := len(sl) - 1; i >= 0; i-- {
1802 // Update sub for outer symbol, then return
1807 // SortSyms sorts a list of symbols by their value.
1808 func (l *Loader) SortSyms(ss []Sym) {
1809 sort.SliceStable(ss, func(i, j int) bool { return l.SymValue(ss[i]) < l.SymValue(ss[j]) })
1812 // Insure that reachable bitmap and its siblings have enough size.
1813 func (l *Loader) growAttrBitmaps(reqLen int) {
1814 if reqLen > l.attrReachable.Len() {
1815 // These are indexed by global symbol
1816 l.attrReachable = growBitmap(reqLen, l.attrReachable)
1817 l.attrOnList = growBitmap(reqLen, l.attrOnList)
1818 l.attrLocal = growBitmap(reqLen, l.attrLocal)
1819 l.attrNotInSymbolTable = growBitmap(reqLen, l.attrNotInSymbolTable)
1820 l.attrUsedInIface = growBitmap(reqLen, l.attrUsedInIface)
1822 l.growExtAttrBitmaps()
1825 func (l *Loader) growExtAttrBitmaps() {
1826 // These are indexed by external symbol index (e.g. l.extIndex(i))
1827 extReqLen := len(l.payloads)
1828 if extReqLen > l.attrVisibilityHidden.Len() {
1829 l.attrVisibilityHidden = growBitmap(extReqLen, l.attrVisibilityHidden)
1830 l.attrDuplicateOK = growBitmap(extReqLen, l.attrDuplicateOK)
1831 l.attrShared = growBitmap(extReqLen, l.attrShared)
1832 l.attrExternal = growBitmap(extReqLen, l.attrExternal)
1836 func (relocs *Relocs) Count() int { return len(relocs.rs) }
1838 // At returns the j-th reloc for a global symbol.
1839 func (relocs *Relocs) At(j int) Reloc {
1840 if relocs.l.isExtReader(relocs.r) {
1841 return Reloc{&relocs.rs[j], relocs.r, relocs.l}
1843 return Reloc{&relocs.rs[j], relocs.r, relocs.l}
1846 // Relocs returns a Relocs object for the given global sym.
1847 func (l *Loader) Relocs(i Sym) Relocs {
1848 r, li := l.toLocal(i)
1850 panic(fmt.Sprintf("trying to get oreader for invalid sym %d\n\n", i))
1852 return l.relocs(r, li)
1855 // Relocs returns a Relocs object given a local sym index and reader.
1856 func (l *Loader) relocs(r *oReader, li uint32) Relocs {
1857 var rs []goobj.Reloc
1858 if l.isExtReader(r) {
1859 pp := l.payloads[li]
1872 func (l *Loader) auxs(i Sym) (*oReader, []goobj.Aux) {
1873 if l.IsExternal(i) {
1874 pp := l.getPayload(i)
1875 return l.objs[pp.objidx].r, pp.auxs
1877 r, li := l.toLocal(i)
1878 return r, r.Auxs(li)
1882 // Returns a specific aux symbol of type t for symbol i.
1883 func (l *Loader) aux1(i Sym, t uint8) Sym {
1884 r, auxs := l.auxs(i)
1885 for j := range auxs {
1888 return l.resolve(r, a.Sym())
1894 func (l *Loader) Pcsp(i Sym) Sym { return l.aux1(i, goobj.AuxPcsp) }
1896 // Returns all aux symbols of per-PC data for symbol i.
1897 // tmp is a scratch space for the pcdata slice.
1898 func (l *Loader) PcdataAuxs(i Sym, tmp []Sym) (pcsp, pcfile, pcline, pcinline Sym, pcdata []Sym) {
1900 r, auxs := l.auxs(i)
1901 for j := range auxs {
1905 pcsp = l.resolve(r, a.Sym())
1906 case goobj.AuxPcline:
1907 pcline = l.resolve(r, a.Sym())
1908 case goobj.AuxPcfile:
1909 pcfile = l.resolve(r, a.Sym())
1910 case goobj.AuxPcinline:
1911 pcinline = l.resolve(r, a.Sym())
1912 case goobj.AuxPcdata:
1913 pcdata = append(pcdata, l.resolve(r, a.Sym()))
1919 // Returns the number of pcdata for symbol i.
1920 func (l *Loader) NumPcdata(i Sym) int {
1922 _, auxs := l.auxs(i)
1923 for j := range auxs {
1925 if a.Type() == goobj.AuxPcdata {
1932 // Returns all funcdata symbols of symbol i.
1933 // tmp is a scratch space.
1934 func (l *Loader) Funcdata(i Sym, tmp []Sym) []Sym {
1936 r, auxs := l.auxs(i)
1937 for j := range auxs {
1939 if a.Type() == goobj.AuxFuncdata {
1940 fd = append(fd, l.resolve(r, a.Sym()))
1946 // Returns the number of funcdata for symbol i.
1947 func (l *Loader) NumFuncdata(i Sym) int {
1949 _, auxs := l.auxs(i)
1950 for j := range auxs {
1952 if a.Type() == goobj.AuxFuncdata {
1959 // FuncInfo provides hooks to access goobj.FuncInfo in the objects.
1960 type FuncInfo struct {
1964 lengths goobj.FuncInfoLengths
1967 func (fi *FuncInfo) Valid() bool { return fi.r != nil }
1969 func (fi *FuncInfo) Args() int {
1970 return int((*goobj.FuncInfo)(nil).ReadArgs(fi.data))
1973 func (fi *FuncInfo) Locals() int {
1974 return int((*goobj.FuncInfo)(nil).ReadLocals(fi.data))
1977 func (fi *FuncInfo) FuncID() objabi.FuncID {
1978 return (*goobj.FuncInfo)(nil).ReadFuncID(fi.data)
1981 func (fi *FuncInfo) FuncFlag() objabi.FuncFlag {
1982 return (*goobj.FuncInfo)(nil).ReadFuncFlag(fi.data)
1985 // Preload has to be called prior to invoking the various methods
1986 // below related to pcdata, funcdataoff, files, and inltree nodes.
1987 func (fi *FuncInfo) Preload() {
1988 fi.lengths = (*goobj.FuncInfo)(nil).ReadFuncInfoLengths(fi.data)
1991 func (fi *FuncInfo) NumFile() uint32 {
1992 if !fi.lengths.Initialized {
1993 panic("need to call Preload first")
1995 return fi.lengths.NumFile
1998 func (fi *FuncInfo) File(k int) goobj.CUFileIndex {
1999 if !fi.lengths.Initialized {
2000 panic("need to call Preload first")
2002 return (*goobj.FuncInfo)(nil).ReadFile(fi.data, fi.lengths.FileOff, uint32(k))
2005 // TopFrame returns true if the function associated with this FuncInfo
2006 // is an entry point, meaning that unwinders should stop when they hit
2008 func (fi *FuncInfo) TopFrame() bool {
2009 return (fi.FuncFlag() & objabi.FuncFlag_TOPFRAME) != 0
2012 type InlTreeNode struct {
2014 File goobj.CUFileIndex
2020 func (fi *FuncInfo) NumInlTree() uint32 {
2021 if !fi.lengths.Initialized {
2022 panic("need to call Preload first")
2024 return fi.lengths.NumInlTree
2027 func (fi *FuncInfo) InlTree(k int) InlTreeNode {
2028 if !fi.lengths.Initialized {
2029 panic("need to call Preload first")
2031 node := (*goobj.FuncInfo)(nil).ReadInlTree(fi.data, fi.lengths.InlTreeOff, uint32(k))
2033 Parent: node.Parent,
2036 Func: fi.l.resolve(fi.r, node.Func),
2037 ParentPC: node.ParentPC,
2041 func (l *Loader) FuncInfo(i Sym) FuncInfo {
2042 r, auxs := l.auxs(i)
2043 for j := range auxs {
2045 if a.Type() == goobj.AuxFuncInfo {
2046 b := r.Data(a.Sym().SymIdx)
2047 return FuncInfo{l, r, b, goobj.FuncInfoLengths{}}
2053 // Preload a package: adds autolib.
2054 // Does not add defined package or non-packaged symbols to the symbol table.
2055 // These are done in LoadSyms.
2056 // Does not read symbol data.
2057 // Returns the fingerprint of the object.
2058 func (l *Loader) Preload(localSymVersion int, f *bio.Reader, lib *sym.Library, unit *sym.CompilationUnit, length int64) goobj.FingerprintType {
2059 roObject, readonly, err := f.Slice(uint64(length)) // TODO: no need to map blocks that are for tools only (e.g. RefName)
2061 log.Fatal("cannot read object file:", err)
2063 r := goobj.NewReaderFromBytes(roObject, readonly)
2065 if len(roObject) >= 8 && bytes.Equal(roObject[:8], []byte("\x00go114ld")) {
2066 log.Fatalf("found object file %s in old format", f.File().Name())
2068 panic("cannot read object file")
2070 pkgprefix := objabi.PathToPrefix(lib.Pkg) + "."
2072 nhashed64def := r.NHashed64def()
2073 nhasheddef := r.NHasheddef()
2077 version: localSymVersion,
2078 pkgprefix: pkgprefix,
2079 syms: make([]Sym, ndef+nhashed64def+nhasheddef+r.NNonpkgdef()+r.NNonpkgref()),
2081 nhasheddef: nhasheddef,
2082 nhashed64def: nhashed64def,
2083 objidx: uint32(len(l.objs)),
2087 lib.Autolib = append(lib.Autolib, r.Autolib()...)
2091 unit.FileTable = make([]string, nfile)
2092 for i := range unit.FileTable {
2093 unit.FileTable[i] = r.File(i)
2096 l.addObj(lib.Pkg, or)
2098 // The caller expects us consuming all the data
2099 f.MustSeek(length, os.SEEK_CUR)
2101 return r.Fingerprint()
2104 // Holds the loader along with temporary states for loading symbols.
2105 type loadState struct {
2107 hashed64Syms map[uint64]symAndSize // short hashed (content-addressable) symbols, keyed by content hash
2108 hashedSyms map[goobj.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
2111 // Preload symbols of given kind from an object.
2112 func (st *loadState) preloadSyms(r *oReader, kind int) {
2114 var start, end uint32
2118 end = uint32(r.ndef)
2120 start = uint32(r.ndef)
2121 end = uint32(r.ndef + r.nhashed64def)
2123 start = uint32(r.ndef + r.nhashed64def)
2124 end = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
2125 if l.hasUnknownPkgPath {
2126 // The content hash depends on symbol name expansion. If any package is
2127 // built without fully expanded names, the content hash is unreliable.
2128 // Treat them as named symbols.
2130 // (We don't need to do this for hashed64Def case, as there the hash
2131 // function is simply the identity function, which doesn't depend on
2136 start = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
2137 end = uint32(r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef())
2139 panic("preloadSyms: bad kind")
2141 l.growAttrBitmaps(len(l.objSyms) + int(end-start))
2142 needNameExpansion := r.NeedNameExpansion()
2143 loadingRuntimePkg := r.unit.Lib.Pkg == "runtime"
2144 for i := start; i < end; i++ {
2148 if kind != hashed64Def && kind != hashedDef { // we don't need the name, etc. for hashed symbols
2149 name = osym.Name(r.Reader)
2150 if needNameExpansion {
2151 name = strings.Replace(name, "\"\".", r.pkgprefix, -1)
2153 v = abiToVer(osym.ABI(), r.version)
2155 gi := st.addSym(name, v, r, i, kind, osym)
2158 l.SetAttrLocal(gi, true)
2160 if osym.UsedInIface() {
2161 l.SetAttrUsedInIface(gi, true)
2163 if strings.HasPrefix(name, "runtime.") ||
2164 (loadingRuntimePkg && strings.HasPrefix(name, "type.")) {
2165 if bi := goobj.BuiltinIdx(name, int(osym.ABI())); bi != -1 {
2166 // This is a definition of a builtin symbol. Record where it is.
2167 l.builtinSyms[bi] = gi
2170 if a := int32(osym.Align()); a != 0 && a > l.SymAlign(gi) {
2171 l.SetSymAlign(gi, a)
2176 // Add syms, hashed (content-addressable) symbols, non-package symbols, and
2177 // references to external symbols (which are always named).
2178 func (l *Loader) LoadSyms(arch *sys.Arch) {
2179 // Allocate space for symbols, making a guess as to how much space we need.
2180 // This function was determined empirically by looking at the cmd/compile on
2181 // Darwin, and picking factors for hashed and hashed64 syms.
2182 var symSize, hashedSize, hashed64Size int
2183 for _, o := range l.objs[goObjStart:] {
2184 symSize += o.r.ndef + o.r.nhasheddef/2 + o.r.nhashed64def/2 + o.r.NNonpkgdef()
2185 hashedSize += o.r.nhasheddef / 2
2186 hashed64Size += o.r.nhashed64def / 2
2188 // Index 0 is invalid for symbols.
2189 l.objSyms = make([]objSym, 1, symSize)
2193 hashed64Syms: make(map[uint64]symAndSize, hashed64Size),
2194 hashedSyms: make(map[goobj.HashType]symAndSize, hashedSize),
2197 for _, o := range l.objs[goObjStart:] {
2198 st.preloadSyms(o.r, pkgDef)
2200 l.npkgsyms = l.NSym()
2201 for _, o := range l.objs[goObjStart:] {
2202 st.preloadSyms(o.r, hashed64Def)
2203 st.preloadSyms(o.r, hashedDef)
2204 st.preloadSyms(o.r, nonPkgDef)
2206 l.nhashedsyms = len(st.hashed64Syms) + len(st.hashedSyms)
2207 for _, o := range l.objs[goObjStart:] {
2208 loadObjRefs(l, o.r, arch)
2210 l.values = make([]int64, l.NSym(), l.NSym()+1000) // +1000 make some room for external symbols
2213 func loadObjRefs(l *Loader, r *oReader, arch *sys.Arch) {
2214 // load non-package refs
2215 ndef := uint32(r.NAlldef())
2216 needNameExpansion := r.NeedNameExpansion()
2217 for i, n := uint32(0), uint32(r.NNonpkgref()); i < n; i++ {
2218 osym := r.Sym(ndef + i)
2219 name := osym.Name(r.Reader)
2220 if needNameExpansion {
2221 name = strings.Replace(name, "\"\".", r.pkgprefix, -1)
2223 v := abiToVer(osym.ABI(), r.version)
2224 r.syms[ndef+i] = l.LookupOrCreateSym(name, v)
2225 gi := r.syms[ndef+i]
2227 l.SetAttrLocal(gi, true)
2229 if osym.UsedInIface() {
2230 l.SetAttrUsedInIface(gi, true)
2234 // referenced packages
2236 r.pkg = make([]uint32, npkg)
2237 for i := 1; i < npkg; i++ { // PkgIdx 0 is a dummy invalid package
2239 objidx, ok := l.objByPkg[pkg]
2241 log.Fatalf("%v: reference to nonexistent package %s", r.unit.Lib, pkg)
2246 // load flags of package refs
2247 for i, n := 0, r.NRefFlags(); i < n; i++ {
2249 gi := l.resolve(r, rf.Sym())
2250 if rf.Flag2()&goobj.SymFlagUsedInIface != 0 {
2251 l.SetAttrUsedInIface(gi, true)
2256 func abiToVer(abi uint16, localSymVersion int) int {
2258 if abi == goobj.SymABIstatic {
2261 } else if abiver := sym.ABIToVersion(obj.ABI(abi)); abiver != -1 {
2262 // Note that data symbols are "ABI0", which maps to version 0.
2265 log.Fatalf("invalid symbol ABI: %d", abi)
2270 // TopLevelSym tests a symbol (by 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 (l *Loader) TopLevelSym(s Sym) bool {
2275 return topLevelSym(l.RawSymName(s), l.SymType(s))
2278 // topLevelSym tests a symbol name and kind to determine whether
2279 // the symbol first class sym (participating in the link) or is an
2280 // anonymous aux or sub-symbol containing some sub-part or payload of
2282 func topLevelSym(sname string, skind sym.SymKind) bool {
2287 case sym.SDWARFFCN, sym.SDWARFABSFCN, sym.SDWARFTYPE, sym.SDWARFCONST, sym.SDWARFCUINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES, sym.SGOFUNC:
2294 // cloneToExternal takes the existing object file symbol (symIdx)
2295 // and creates a new external symbol payload that is a clone with
2296 // respect to name, version, type, relocations, etc. The idea here
2297 // is that if the linker decides it wants to update the contents of
2298 // a symbol originally discovered as part of an object file, it's
2299 // easier to do this if we make the updates to an external symbol
2301 func (l *Loader) cloneToExternal(symIdx Sym) {
2302 if l.IsExternal(symIdx) {
2303 panic("sym is already external, no need for clone")
2306 // Read the particulars from object.
2307 r, li := l.toLocal(symIdx)
2309 sname := osym.Name(r.Reader)
2310 if r.NeedNameExpansion() {
2311 sname = strings.Replace(sname, "\"\".", r.pkgprefix, -1)
2313 sver := abiToVer(osym.ABI(), r.version)
2314 skind := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
2316 // Create new symbol, update version and kind.
2317 pi := l.newPayload(sname, sver)
2318 pp := l.payloads[pi]
2321 pp.size = int64(osym.Siz())
2322 pp.objidx = r.objidx
2324 // If this is a def, then copy the guts. We expect this case
2325 // to be very rare (one case it may come up is with -X).
2326 if li < uint32(r.NAlldef()) {
2329 relocs := l.Relocs(symIdx)
2330 pp.relocs = make([]goobj.Reloc, relocs.Count())
2331 for i := range pp.relocs {
2332 // Copy the relocs slice.
2333 // Convert local reference to global reference.
2335 pp.relocs[i].Set(rel.Off(), rel.Siz(), uint16(rel.Type()), rel.Add(), goobj.SymRef{PkgIdx: 0, SymIdx: uint32(rel.Sym())})
2339 pp.data = r.Data(li)
2342 // If we're overriding a data symbol, collect the associated
2343 // Gotype, so as to propagate it to the new symbol.
2347 // Install new payload to global index space.
2348 // (This needs to happen at the end, as the accessors above
2349 // need to access the old symbol content.)
2350 l.objSyms[symIdx] = objSym{l.extReader.objidx, uint32(pi)}
2351 l.extReader.syms = append(l.extReader.syms, symIdx)
2354 // Copy the payload of symbol src to dst. Both src and dst must be external
2356 // The intended use case is that when building/linking against a shared library,
2357 // where we do symbol name mangling, the Go object file may have reference to
2358 // the original symbol name whereas the shared library provides a symbol with
2359 // the mangled name. When we do mangling, we copy payload of mangled to original.
2360 func (l *Loader) CopySym(src, dst Sym) {
2361 if !l.IsExternal(dst) {
2362 panic("dst is not external") //l.newExtSym(l.SymName(dst), l.SymVersion(dst))
2364 if !l.IsExternal(src) {
2365 panic("src is not external") //l.cloneToExternal(src)
2367 l.payloads[l.extIndex(dst)] = l.payloads[l.extIndex(src)]
2368 l.SetSymPkg(dst, l.SymPkg(src))
2369 // TODO: other attributes?
2372 // CopyAttributes copies over all of the attributes of symbol 'src' to
2374 func (l *Loader) CopyAttributes(src Sym, dst Sym) {
2375 l.SetAttrReachable(dst, l.AttrReachable(src))
2376 l.SetAttrOnList(dst, l.AttrOnList(src))
2377 l.SetAttrLocal(dst, l.AttrLocal(src))
2378 l.SetAttrNotInSymbolTable(dst, l.AttrNotInSymbolTable(src))
2379 if l.IsExternal(dst) {
2380 l.SetAttrVisibilityHidden(dst, l.AttrVisibilityHidden(src))
2381 l.SetAttrDuplicateOK(dst, l.AttrDuplicateOK(src))
2382 l.SetAttrShared(dst, l.AttrShared(src))
2383 l.SetAttrExternal(dst, l.AttrExternal(src))
2385 // Some attributes are modifiable only for external symbols.
2386 // In such cases, don't try to transfer over the attribute
2387 // from the source even if there is a clash. This comes up
2388 // when copying attributes from a dupOK ABI wrapper symbol to
2389 // the real target symbol (which may not be marked dupOK).
2391 l.SetAttrSpecial(dst, l.AttrSpecial(src))
2392 l.SetAttrCgoExportDynamic(dst, l.AttrCgoExportDynamic(src))
2393 l.SetAttrCgoExportStatic(dst, l.AttrCgoExportStatic(src))
2394 l.SetAttrReadOnly(dst, l.AttrReadOnly(src))
2397 // CreateExtSym creates a new external symbol with the specified name
2398 // without adding it to any lookup tables, returning a Sym index for it.
2399 func (l *Loader) CreateExtSym(name string, ver int) Sym {
2400 return l.newExtSym(name, ver)
2403 // CreateStaticSym creates a new static symbol with the specified name
2404 // without adding it to any lookup tables, returning a Sym index for it.
2405 func (l *Loader) CreateStaticSym(name string) Sym {
2406 // Assign a new unique negative version -- this is to mark the
2407 // symbol so that it is not included in the name lookup table.
2409 return l.newExtSym(name, l.anonVersion)
2412 func (l *Loader) FreeSym(i Sym) {
2413 if l.IsExternal(i) {
2414 pp := l.getPayload(i)
2415 *pp = extSymPayload{}
2419 // relocId is essentially a <S,R> tuple identifying the Rth
2420 // relocation of symbol S.
2421 type relocId struct {
2426 // SetRelocVariant sets the 'variant' property of a relocation on
2427 // some specific symbol.
2428 func (l *Loader) SetRelocVariant(s Sym, ri int, v sym.RelocVariant) {
2430 if relocs := l.Relocs(s); ri >= relocs.Count() {
2431 panic("invalid relocation ID")
2433 if l.relocVariant == nil {
2434 l.relocVariant = make(map[relocId]sym.RelocVariant)
2437 l.relocVariant[relocId{s, ri}] = v
2439 delete(l.relocVariant, relocId{s, ri})
2443 // RelocVariant returns the 'variant' property of a relocation on
2444 // some specific symbol.
2445 func (l *Loader) RelocVariant(s Sym, ri int) sym.RelocVariant {
2446 return l.relocVariant[relocId{s, ri}]
2449 // UndefinedRelocTargets iterates through the global symbol index
2450 // space, looking for symbols with relocations targeting undefined
2451 // references. The linker's loadlib method uses this to determine if
2452 // there are unresolved references to functions in system libraries
2453 // (for example, libgcc.a), presumably due to CGO code. Return
2454 // value is a list of loader.Sym's corresponding to the undefined
2455 // cross-refs. The "limit" param controls the maximum number of
2456 // results returned; if "limit" is -1, then all undefs are returned.
2457 func (l *Loader) UndefinedRelocTargets(limit int) []Sym {
2459 for si := Sym(1); si < Sym(len(l.objSyms)); si++ {
2460 relocs := l.Relocs(si)
2461 for ri := 0; ri < relocs.Count(); ri++ {
2464 if rs != 0 && l.SymType(rs) == sym.SXREF && l.RawSymName(rs) != ".got" {
2465 result = append(result, rs)
2466 if limit != -1 && len(result) >= limit {
2475 // AssignTextSymbolOrder populates the Textp slices within each
2476 // library and compilation unit, insuring that packages are laid down
2477 // in dependency order (internal first, then everything else). Return value
2478 // is a slice of all text syms.
2479 func (l *Loader) AssignTextSymbolOrder(libs []*sym.Library, intlibs []bool, extsyms []Sym) []Sym {
2481 // Library Textp lists should be empty at this point.
2482 for _, lib := range libs {
2483 if len(lib.Textp) != 0 {
2484 panic("expected empty Textp slice for library")
2486 if len(lib.DupTextSyms) != 0 {
2487 panic("expected empty DupTextSyms slice for library")
2491 // Used to record which dupok symbol we've assigned to a unit.
2492 // Can't use the onlist attribute here because it will need to
2493 // clear for the later assignment of the sym.Symbol to a unit.
2494 // NB: we can convert to using onList once we no longer have to
2495 // call the regular addToTextp.
2496 assignedToUnit := MakeBitmap(l.NSym() + 1)
2498 // Start off textp with reachable external syms.
2500 for _, sym := range extsyms {
2501 if !l.attrReachable.Has(sym) {
2504 textp = append(textp, sym)
2507 // Walk through all text symbols from Go object files and append
2508 // them to their corresponding library's textp list.
2509 for _, o := range l.objs[goObjStart:] {
2512 for i, n := uint32(0), uint32(r.NAlldef()); i < n; i++ {
2513 gi := l.toGlobal(r, i)
2514 if !l.attrReachable.Has(gi) {
2518 st := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
2519 if st != sym.STEXT {
2522 dupok := osym.Dupok()
2523 if r2, i2 := l.toLocal(gi); r2 != r || i2 != i {
2524 // A dupok text symbol is resolved to another package.
2525 // We still need to record its presence in the current
2526 // package, as the trampoline pass expects packages
2527 // are laid out in dependency order.
2528 lib.DupTextSyms = append(lib.DupTextSyms, sym.LoaderSym(gi))
2529 continue // symbol in different object
2532 lib.DupTextSyms = append(lib.DupTextSyms, sym.LoaderSym(gi))
2536 lib.Textp = append(lib.Textp, sym.LoaderSym(gi))
2540 // Now assemble global textp, and assign text symbols to units.
2541 for _, doInternal := range [2]bool{true, false} {
2542 for idx, lib := range libs {
2543 if intlibs[idx] != doInternal {
2546 lists := [2][]sym.LoaderSym{lib.Textp, lib.DupTextSyms}
2547 for i, list := range lists {
2548 for _, s := range list {
2550 if !assignedToUnit.Has(sym) {
2551 textp = append(textp, sym)
2552 unit := l.SymUnit(sym)
2554 unit.Textp = append(unit.Textp, s)
2555 assignedToUnit.Set(sym)
2557 // Dupok symbols may be defined in multiple packages; the
2558 // associated package for a dupok sym is chosen sort of
2559 // arbitrarily (the first containing package that the linker
2560 // loads). Canonicalizes its Pkg to the package with which
2561 // it will be laid down in text.
2562 if i == 1 /* DupTextSyms2 */ && l.SymPkg(sym) != lib.Pkg {
2563 l.SetSymPkg(sym, lib.Pkg)
2569 lib.DupTextSyms = nil
2576 // ErrorReporter is a helper class for reporting errors.
2577 type ErrorReporter struct {
2579 AfterErrorAction func()
2582 // Errorf method logs an error message.
2584 // After each error, the error actions function will be invoked; this
2585 // will either terminate the link immediately (if -h option given)
2586 // or it will keep a count and exit if more than 20 errors have been printed.
2588 // Logging an error means that on exit cmd/link will delete any
2589 // output file and return a non-zero error code.
2591 func (reporter *ErrorReporter) Errorf(s Sym, format string, args ...interface{}) {
2592 if s != 0 && reporter.ldr.SymName(s) != "" {
2593 // Note: Replace is needed here because symbol names might have % in them,
2594 // due to the use of LinkString for names of instantiating types.
2595 format = strings.Replace(reporter.ldr.SymName(s), "%", "%%", -1) + ": " + format
2597 format = fmt.Sprintf("sym %d: %s", s, format)
2600 fmt.Fprintf(os.Stderr, format, args...)
2601 reporter.AfterErrorAction()
2604 // GetErrorReporter returns the loader's associated error reporter.
2605 func (l *Loader) GetErrorReporter() *ErrorReporter {
2606 return l.errorReporter
2609 // Errorf method logs an error message. See ErrorReporter.Errorf for details.
2610 func (l *Loader) Errorf(s Sym, format string, args ...interface{}) {
2611 l.errorReporter.Errorf(s, format, args...)
2614 // Symbol statistics.
2615 func (l *Loader) Stat() string {
2616 s := fmt.Sprintf("%d symbols, %d reachable\n", l.NSym(), l.NReachableSym())
2617 s += fmt.Sprintf("\t%d package symbols, %d hashed symbols, %d non-package symbols, %d external symbols\n",
2618 l.npkgsyms, l.nhashedsyms, int(l.extStart)-l.npkgsyms-l.nhashedsyms, l.NSym()-int(l.extStart))
2623 func (l *Loader) Dump() {
2625 for _, obj := range l.objs[goObjStart:] {
2627 fmt.Println(obj.i, obj.r.unit.Lib)
2630 fmt.Println("extStart:", l.extStart)
2631 fmt.Println("Nsyms:", len(l.objSyms))
2633 for i := Sym(1); i < Sym(len(l.objSyms)); i++ {
2635 if l.IsExternal(i) {
2636 pi = fmt.Sprintf("<ext %d>", l.extIndex(i))
2639 if l.SymSect(i) != nil {
2640 sect = l.SymSect(i).Name
2642 fmt.Printf("%v %v %v %v %x %v\n", i, l.SymName(i), l.SymType(i), pi, l.SymValue(i), sect)
2644 fmt.Println("symsByName")
2645 for name, i := range l.symsByName[0] {
2646 fmt.Println(i, name, 0)
2648 for name, i := range l.symsByName[1] {
2649 fmt.Println(i, name, 1)
2651 fmt.Println("payloads:")
2652 for i := range l.payloads {
2654 fmt.Println(i, pp.name, pp.ver, pp.kind)