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.
11 "cmd/link/internal/sym"
16 // SymbolBuilder is a helper designed to help with the construction
17 // of new symbol contents.
18 type SymbolBuilder struct {
19 *extSymPayload // points to payload being updated
20 symIdx Sym // index of symbol being updated/constructed
24 // MakeSymbolBuilder creates a symbol builder for use in constructing
25 // an entirely new symbol.
26 func (l *Loader) MakeSymbolBuilder(name string) *SymbolBuilder {
27 // for now assume that any new sym is intended to be static
28 symIdx := l.CreateStaticSym(name)
29 if l.Syms[symIdx] != nil {
30 panic("can't build if sym.Symbol already present")
32 sb := &SymbolBuilder{l: l, symIdx: symIdx}
33 sb.extSymPayload = l.getPayload(symIdx)
37 // MakeSymbolUpdater creates a symbol builder helper for an existing
38 // symbol 'symIdx'. If 'symIdx' is not an external symbol, then create
39 // a clone of it (copy name, properties, etc) fix things up so that
40 // the lookup tables and caches point to the new version, not the old
42 func (l *Loader) MakeSymbolUpdater(symIdx Sym) *SymbolBuilder {
44 panic("can't update the null symbol")
46 if !l.IsExternal(symIdx) {
47 // Create a clone with the same name/version/kind etc.
48 l.cloneToExternal(symIdx)
50 // Now that we're doing phase 2 DWARF generation using the loader
51 // but before the wavefront has reached dodata(), we can't have this
52 // assertion here. Commented out for now.
54 if l.Syms[symIdx] != nil {
55 panic(fmt.Sprintf("can't build if sym.Symbol %q already present", l.RawSymName(symIdx)))
59 // Construct updater and return.
60 sb := &SymbolBuilder{l: l, symIdx: symIdx}
61 sb.extSymPayload = l.getPayload(symIdx)
65 // CreateSymForUpdate creates a symbol with given name and version,
66 // returns a CreateSymForUpdate for update. If the symbol already
67 // exists, it will update in-place.
68 func (l *Loader) CreateSymForUpdate(name string, version int) *SymbolBuilder {
69 return l.MakeSymbolUpdater(l.LookupOrCreateSym(name, version))
72 // Getters for properties of the symbol we're working on.
74 func (sb *SymbolBuilder) Sym() Sym { return sb.symIdx }
75 func (sb *SymbolBuilder) Name() string { return sb.name }
76 func (sb *SymbolBuilder) Version() int { return sb.ver }
77 func (sb *SymbolBuilder) Type() sym.SymKind { return sb.kind }
78 func (sb *SymbolBuilder) Size() int64 { return sb.size }
79 func (sb *SymbolBuilder) Data() []byte { return sb.data }
80 func (sb *SymbolBuilder) Value() int64 { return sb.l.SymValue(sb.symIdx) }
81 func (sb *SymbolBuilder) Align() int32 { return sb.l.SymAlign(sb.symIdx) }
82 func (sb *SymbolBuilder) Localentry() uint8 { return sb.l.SymLocalentry(sb.symIdx) }
83 func (sb *SymbolBuilder) OnList() bool { return sb.l.AttrOnList(sb.symIdx) }
84 func (sb *SymbolBuilder) External() bool { return sb.l.AttrExternal(sb.symIdx) }
85 func (sb *SymbolBuilder) Extname() string { return sb.l.SymExtname(sb.symIdx) }
86 func (sb *SymbolBuilder) CgoExportDynamic() bool { return sb.l.AttrCgoExportDynamic(sb.symIdx) }
87 func (sb *SymbolBuilder) Dynimplib() string { return sb.l.SymDynimplib(sb.symIdx) }
88 func (sb *SymbolBuilder) Dynimpvers() string { return sb.l.SymDynimpvers(sb.symIdx) }
89 func (sb *SymbolBuilder) SubSym() Sym { return sb.l.SubSym(sb.symIdx) }
90 func (sb *SymbolBuilder) GoType() Sym { return sb.l.SymGoType(sb.symIdx) }
91 func (sb *SymbolBuilder) VisibilityHidden() bool { return sb.l.AttrVisibilityHidden(sb.symIdx) }
92 func (sb *SymbolBuilder) Sect() *sym.Section { return sb.l.SymSect(sb.symIdx) }
94 // Setters for symbol properties.
96 func (sb *SymbolBuilder) SetType(kind sym.SymKind) { sb.kind = kind }
97 func (sb *SymbolBuilder) SetSize(size int64) { sb.size = size }
98 func (sb *SymbolBuilder) SetData(data []byte) { sb.data = data }
99 func (sb *SymbolBuilder) SetOnList(v bool) { sb.l.SetAttrOnList(sb.symIdx, v) }
100 func (sb *SymbolBuilder) SetExternal(v bool) { sb.l.SetAttrExternal(sb.symIdx, v) }
101 func (sb *SymbolBuilder) SetValue(v int64) { sb.l.SetSymValue(sb.symIdx, v) }
102 func (sb *SymbolBuilder) SetAlign(align int32) { sb.l.SetSymAlign(sb.symIdx, align) }
103 func (sb *SymbolBuilder) SetLocalentry(value uint8) { sb.l.SetSymLocalentry(sb.symIdx, value) }
104 func (sb *SymbolBuilder) SetExtname(value string) { sb.l.SetSymExtname(sb.symIdx, value) }
105 func (sb *SymbolBuilder) SetDynimplib(value string) { sb.l.SetSymDynimplib(sb.symIdx, value) }
106 func (sb *SymbolBuilder) SetDynimpvers(value string) { sb.l.SetSymDynimpvers(sb.symIdx, value) }
107 func (sb *SymbolBuilder) SetPlt(value int32) { sb.l.SetPlt(sb.symIdx, value) }
108 func (sb *SymbolBuilder) SetGot(value int32) { sb.l.SetGot(sb.symIdx, value) }
109 func (sb *SymbolBuilder) SetSpecial(value bool) { sb.l.SetAttrSpecial(sb.symIdx, value) }
110 func (sb *SymbolBuilder) SetLocal(value bool) { sb.l.SetAttrLocal(sb.symIdx, value) }
111 func (sb *SymbolBuilder) SetVisibilityHidden(value bool) {
112 sb.l.SetAttrVisibilityHidden(sb.symIdx, value)
114 func (sb *SymbolBuilder) SetNotInSymbolTable(value bool) {
115 sb.l.SetAttrNotInSymbolTable(sb.symIdx, value)
117 func (sb *SymbolBuilder) SetSect(sect *sym.Section) { sb.l.SetSymSect(sb.symIdx, sect) }
119 func (sb *SymbolBuilder) AddBytes(data []byte) {
124 sb.data = append(sb.data, data...)
125 sb.size = int64(len(sb.data))
128 func (sb *SymbolBuilder) Relocs() Relocs {
129 return sb.l.Relocs(sb.symIdx)
132 func (sb *SymbolBuilder) SetRelocs(rslice []Reloc) {
134 if cap(sb.relocs) < n {
135 sb.relocs = make([]goobj2.Reloc, n)
136 sb.reltypes = make([]objabi.RelocType, n)
138 sb.relocs = sb.relocs[:n]
139 sb.reltypes = sb.reltypes[:n]
141 for i := range rslice {
142 sb.SetReloc(i, rslice[i])
146 // SetRelocType sets the type of the 'i'-th relocation on this sym to 't'
147 func (sb *SymbolBuilder) SetRelocType(i int, t objabi.RelocType) {
148 sb.relocs[i].SetType(0)
152 // SetRelocSym sets the target sym of the 'i'-th relocation on this sym to 's'
153 func (sb *SymbolBuilder) SetRelocSym(i int, tgt Sym) {
154 sb.relocs[i].SetSym(goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(tgt)})
157 // SetRelocAdd sets the addend of the 'i'-th relocation on this sym to 'a'
158 func (sb *SymbolBuilder) SetRelocAdd(i int, a int64) {
159 sb.relocs[i].SetAdd(a)
162 // Add n relocations, return a handle to the relocations.
163 func (sb *SymbolBuilder) AddRelocs(n int) Relocs {
164 sb.relocs = append(sb.relocs, make([]goobj2.Reloc, n)...)
165 sb.reltypes = append(sb.reltypes, make([]objabi.RelocType, n)...)
166 return sb.l.Relocs(sb.symIdx)
169 // Add a relocation with given type, return its handle and index
170 // (to set other fields).
171 func (sb *SymbolBuilder) AddRel(typ objabi.RelocType) (Reloc2, int) {
173 sb.relocs = append(sb.relocs, goobj2.Reloc{})
174 sb.reltypes = append(sb.reltypes, typ)
175 relocs := sb.Relocs()
176 return relocs.At2(j), j
179 // Sort relocations by offset.
180 func (sb *SymbolBuilder) SortRelocs() {
181 sort.Sort((*relocsByOff)(sb.extSymPayload))
184 // Implement sort.Interface
185 type relocsByOff extSymPayload
187 func (p *relocsByOff) Len() int { return len(p.relocs) }
188 func (p *relocsByOff) Less(i, j int) bool { return p.relocs[i].Off() < p.relocs[j].Off() }
189 func (p *relocsByOff) Swap(i, j int) {
190 p.relocs[i], p.relocs[j] = p.relocs[j], p.relocs[i]
191 p.reltypes[i], p.reltypes[j] = p.reltypes[j], p.reltypes[i]
194 // AddReloc appends the specified reloc to the symbols list of
195 // relocations. Return value is the index of the newly created
197 func (sb *SymbolBuilder) AddReloc(r Reloc) uint32 {
198 // Populate a goobj2.Reloc from external reloc record.
199 rval := uint32(len(sb.relocs))
201 b.Set(r.Off, r.Size, 0, r.Add, goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(r.Sym)})
202 sb.relocs = append(sb.relocs, b)
203 sb.reltypes = append(sb.reltypes, r.Type)
207 // Update the j-th relocation in place.
208 func (sb *SymbolBuilder) SetReloc(j int, r Reloc) {
209 // Populate a goobj2.Reloc from external reloc record.
210 sb.relocs[j].Set(r.Off, r.Size, 0, r.Add, goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(r.Sym)})
211 sb.reltypes[j] = r.Type
214 func (sb *SymbolBuilder) Reachable() bool {
215 return sb.l.AttrReachable(sb.symIdx)
218 func (sb *SymbolBuilder) SetReachable(v bool) {
219 sb.l.SetAttrReachable(sb.symIdx, v)
222 func (sb *SymbolBuilder) setReachable() {
223 sb.SetReachable(true)
226 func (sb *SymbolBuilder) ReadOnly() bool {
227 return sb.l.AttrReadOnly(sb.symIdx)
230 func (sb *SymbolBuilder) SetReadOnly(v bool) {
231 sb.l.SetAttrReadOnly(sb.symIdx, v)
234 func (sb *SymbolBuilder) DuplicateOK() bool {
235 return sb.l.AttrDuplicateOK(sb.symIdx)
238 func (sb *SymbolBuilder) SetDuplicateOK(v bool) {
239 sb.l.SetAttrDuplicateOK(sb.symIdx, v)
242 func (sb *SymbolBuilder) Outer() Sym {
243 return sb.l.OuterSym(sb.symIdx)
246 func (sb *SymbolBuilder) Sub() Sym {
247 return sb.l.SubSym(sb.symIdx)
250 func (sb *SymbolBuilder) SortSub() {
251 sb.l.SortSub(sb.symIdx)
254 func (sb *SymbolBuilder) PrependSub(sub Sym) {
255 sb.l.PrependSub(sb.symIdx, sub)
258 func (sb *SymbolBuilder) AddUint8(v uint8) int64 {
265 sb.data = append(sb.data, v)
269 func (sb *SymbolBuilder) AddUintXX(arch *sys.Arch, v uint64, wid int) int64 {
272 sb.setUintXX(arch, off, v, int64(wid))
276 func (sb *SymbolBuilder) setUintXX(arch *sys.Arch, off int64, v uint64, wid int64) int64 {
280 if sb.size < off+wid {
287 sb.data[off] = uint8(v)
289 arch.ByteOrder.PutUint16(sb.data[off:], uint16(v))
291 arch.ByteOrder.PutUint32(sb.data[off:], uint32(v))
293 arch.ByteOrder.PutUint64(sb.data[off:], v)
299 func (sb *SymbolBuilder) AddUint16(arch *sys.Arch, v uint16) int64 {
300 return sb.AddUintXX(arch, uint64(v), 2)
303 func (sb *SymbolBuilder) AddUint32(arch *sys.Arch, v uint32) int64 {
304 return sb.AddUintXX(arch, uint64(v), 4)
307 func (sb *SymbolBuilder) AddUint64(arch *sys.Arch, v uint64) int64 {
308 return sb.AddUintXX(arch, v, 8)
311 func (sb *SymbolBuilder) AddUint(arch *sys.Arch, v uint64) int64 {
312 return sb.AddUintXX(arch, v, arch.PtrSize)
315 func (sb *SymbolBuilder) SetUint8(arch *sys.Arch, r int64, v uint8) int64 {
317 return sb.setUintXX(arch, r, uint64(v), 1)
320 func (sb *SymbolBuilder) SetUint16(arch *sys.Arch, r int64, v uint16) int64 {
322 return sb.setUintXX(arch, r, uint64(v), 2)
325 func (sb *SymbolBuilder) SetUint32(arch *sys.Arch, r int64, v uint32) int64 {
327 return sb.setUintXX(arch, r, uint64(v), 4)
330 func (sb *SymbolBuilder) SetUint(arch *sys.Arch, r int64, v uint64) int64 {
332 return sb.setUintXX(arch, r, v, int64(arch.PtrSize))
335 func (sb *SymbolBuilder) SetAddrPlus(arch *sys.Arch, off int64, tgt Sym, add int64) int64 {
337 sb.SetType(sym.SDATA)
340 if off+int64(arch.PtrSize) > sb.size {
341 sb.size = off + int64(arch.PtrSize)
347 r.Size = uint8(arch.PtrSize)
348 r.Type = objabi.R_ADDR
351 return off + int64(r.Size)
354 func (sb *SymbolBuilder) SetAddr(arch *sys.Arch, off int64, tgt Sym) int64 {
355 return sb.SetAddrPlus(arch, off, tgt, 0)
358 func (sb *SymbolBuilder) Addstring(str string) int64 {
361 sb.kind = sym.SNOPTRDATA
364 if sb.name == ".shstrtab" {
365 // FIXME: find a better mechanism for this
366 sb.l.elfsetstring(nil, str, int(r))
368 sb.data = append(sb.data, str...)
369 sb.data = append(sb.data, 0)
370 sb.size = int64(len(sb.data))
374 func (sb *SymbolBuilder) addSymRef(tgt Sym, add int64, typ objabi.RelocType, rsize int) int64 {
380 sb.size += int64(rsize)
386 r.Size = uint8(rsize)
391 return i + int64(r.Size)
394 // Add a symbol reference (relocation) with given type, addend, and size
395 // (the most generic form).
396 func (sb *SymbolBuilder) AddSymRef(arch *sys.Arch, tgt Sym, add int64, typ objabi.RelocType, rsize int) int64 {
398 return sb.addSymRef(tgt, add, typ, rsize)
401 func (sb *SymbolBuilder) AddAddrPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
403 return sb.addSymRef(tgt, add, objabi.R_ADDR, arch.PtrSize)
406 func (sb *SymbolBuilder) AddAddrPlus4(arch *sys.Arch, tgt Sym, add int64) int64 {
408 return sb.addSymRef(tgt, add, objabi.R_ADDR, 4)
411 func (sb *SymbolBuilder) AddAddr(arch *sys.Arch, tgt Sym) int64 {
412 return sb.AddAddrPlus(arch, tgt, 0)
415 func (sb *SymbolBuilder) AddPCRelPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
417 return sb.addSymRef(tgt, add, objabi.R_PCREL, 4)
420 func (sb *SymbolBuilder) AddCURelativeAddrPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
422 return sb.addSymRef(tgt, add, objabi.R_ADDRCUOFF, arch.PtrSize)
425 func (sb *SymbolBuilder) AddSize(arch *sys.Arch, tgt Sym) int64 {
427 return sb.addSymRef(tgt, 0, objabi.R_SIZE, arch.PtrSize)
430 // GenAddAddrPlusFunc returns a function to be called when capturing
431 // a function symbol's address. In later stages of the link (when
432 // address assignment is done) when doing internal linking and
433 // targeting an executable, we can just emit the address of a function
434 // directly instead of generating a relocation. Clients can call
435 // this function (setting 'internalExec' based on build mode and target)
436 // and then invoke the returned function in roughly the same way that
437 // loader.*SymbolBuilder.AddAddrPlus would be used.
438 func GenAddAddrPlusFunc(internalExec bool) func(s *SymbolBuilder, arch *sys.Arch, tgt Sym, add int64) int64 {
440 return func(s *SymbolBuilder, arch *sys.Arch, tgt Sym, add int64) int64 {
441 if v := s.l.SymValue(tgt); v != 0 {
442 return s.AddUint(arch, uint64(v+add))
444 return s.AddAddrPlus(arch, tgt, add)
447 return (*SymbolBuilder).AddAddrPlus
451 func (sb *SymbolBuilder) MakeWritable() {
453 sb.data = append([]byte(nil), sb.data...)
454 sb.l.SetAttrReadOnly(sb.symIdx, false)