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"
15 // SymbolBuilder is a helper designed to help with the construction
16 // of new symbol contents.
17 type SymbolBuilder struct {
18 *extSymPayload // points to payload being updated
19 symIdx Sym // index of symbol being updated/constructed
23 // MakeSymbolBuilder creates a symbol builder for use in constructing
24 // an entirely new symbol.
25 func (l *Loader) MakeSymbolBuilder(name string) *SymbolBuilder {
26 // for now assume that any new sym is intended to be static
27 symIdx := l.CreateStaticSym(name)
28 sb := &SymbolBuilder{l: l, symIdx: symIdx}
29 sb.extSymPayload = l.getPayload(symIdx)
33 // MakeSymbolUpdater creates a symbol builder helper for an existing
34 // symbol 'symIdx'. If 'symIdx' is not an external symbol, then create
35 // a clone of it (copy name, properties, etc) fix things up so that
36 // the lookup tables and caches point to the new version, not the old
38 func (l *Loader) MakeSymbolUpdater(symIdx Sym) *SymbolBuilder {
40 panic("can't update the null symbol")
42 if !l.IsExternal(symIdx) {
43 // Create a clone with the same name/version/kind etc.
44 l.cloneToExternal(symIdx)
47 // Construct updater and return.
48 sb := &SymbolBuilder{l: l, symIdx: symIdx}
49 sb.extSymPayload = l.getPayload(symIdx)
53 // CreateSymForUpdate creates a symbol with given name and version,
54 // returns a CreateSymForUpdate for update. If the symbol already
55 // exists, it will update in-place.
56 func (l *Loader) CreateSymForUpdate(name string, version int) *SymbolBuilder {
57 return l.MakeSymbolUpdater(l.LookupOrCreateSym(name, version))
60 // Getters for properties of the symbol we're working on.
62 func (sb *SymbolBuilder) Sym() Sym { return sb.symIdx }
63 func (sb *SymbolBuilder) Name() string { return sb.name }
64 func (sb *SymbolBuilder) Version() int { return sb.ver }
65 func (sb *SymbolBuilder) Type() sym.SymKind { return sb.kind }
66 func (sb *SymbolBuilder) Size() int64 { return sb.size }
67 func (sb *SymbolBuilder) Data() []byte { return sb.data }
68 func (sb *SymbolBuilder) Value() int64 { return sb.l.SymValue(sb.symIdx) }
69 func (sb *SymbolBuilder) Align() int32 { return sb.l.SymAlign(sb.symIdx) }
70 func (sb *SymbolBuilder) Localentry() uint8 { return sb.l.SymLocalentry(sb.symIdx) }
71 func (sb *SymbolBuilder) OnList() bool { return sb.l.AttrOnList(sb.symIdx) }
72 func (sb *SymbolBuilder) External() bool { return sb.l.AttrExternal(sb.symIdx) }
73 func (sb *SymbolBuilder) Extname() string { return sb.l.SymExtname(sb.symIdx) }
74 func (sb *SymbolBuilder) CgoExportDynamic() bool { return sb.l.AttrCgoExportDynamic(sb.symIdx) }
75 func (sb *SymbolBuilder) Dynimplib() string { return sb.l.SymDynimplib(sb.symIdx) }
76 func (sb *SymbolBuilder) Dynimpvers() string { return sb.l.SymDynimpvers(sb.symIdx) }
77 func (sb *SymbolBuilder) SubSym() Sym { return sb.l.SubSym(sb.symIdx) }
78 func (sb *SymbolBuilder) GoType() Sym { return sb.l.SymGoType(sb.symIdx) }
79 func (sb *SymbolBuilder) VisibilityHidden() bool { return sb.l.AttrVisibilityHidden(sb.symIdx) }
80 func (sb *SymbolBuilder) Sect() *sym.Section { return sb.l.SymSect(sb.symIdx) }
82 // Setters for symbol properties.
84 func (sb *SymbolBuilder) SetType(kind sym.SymKind) { sb.kind = kind }
85 func (sb *SymbolBuilder) SetSize(size int64) { sb.size = size }
86 func (sb *SymbolBuilder) SetData(data []byte) { sb.data = data }
87 func (sb *SymbolBuilder) SetOnList(v bool) { sb.l.SetAttrOnList(sb.symIdx, v) }
88 func (sb *SymbolBuilder) SetExternal(v bool) { sb.l.SetAttrExternal(sb.symIdx, v) }
89 func (sb *SymbolBuilder) SetValue(v int64) { sb.l.SetSymValue(sb.symIdx, v) }
90 func (sb *SymbolBuilder) SetAlign(align int32) { sb.l.SetSymAlign(sb.symIdx, align) }
91 func (sb *SymbolBuilder) SetLocalentry(value uint8) { sb.l.SetSymLocalentry(sb.symIdx, value) }
92 func (sb *SymbolBuilder) SetExtname(value string) { sb.l.SetSymExtname(sb.symIdx, value) }
93 func (sb *SymbolBuilder) SetDynimplib(value string) { sb.l.SetSymDynimplib(sb.symIdx, value) }
94 func (sb *SymbolBuilder) SetDynimpvers(value string) { sb.l.SetSymDynimpvers(sb.symIdx, value) }
95 func (sb *SymbolBuilder) SetPlt(value int32) { sb.l.SetPlt(sb.symIdx, value) }
96 func (sb *SymbolBuilder) SetGot(value int32) { sb.l.SetGot(sb.symIdx, value) }
97 func (sb *SymbolBuilder) SetSpecial(value bool) { sb.l.SetAttrSpecial(sb.symIdx, value) }
98 func (sb *SymbolBuilder) SetLocal(value bool) { sb.l.SetAttrLocal(sb.symIdx, value) }
99 func (sb *SymbolBuilder) SetVisibilityHidden(value bool) {
100 sb.l.SetAttrVisibilityHidden(sb.symIdx, value)
102 func (sb *SymbolBuilder) SetNotInSymbolTable(value bool) {
103 sb.l.SetAttrNotInSymbolTable(sb.symIdx, value)
105 func (sb *SymbolBuilder) SetSect(sect *sym.Section) { sb.l.SetSymSect(sb.symIdx, sect) }
107 func (sb *SymbolBuilder) AddBytes(data []byte) {
112 sb.data = append(sb.data, data...)
113 sb.size = int64(len(sb.data))
116 func (sb *SymbolBuilder) Relocs() Relocs {
117 return sb.l.Relocs(sb.symIdx)
120 func (sb *SymbolBuilder) SetRelocs(rslice []Reloc) {
122 if cap(sb.relocs) < n {
123 sb.relocs = make([]goobj2.Reloc, n)
124 sb.reltypes = make([]objabi.RelocType, n)
126 sb.relocs = sb.relocs[:n]
127 sb.reltypes = sb.reltypes[:n]
129 for i := range rslice {
130 sb.SetReloc(i, rslice[i])
134 // SetRelocType sets the type of the 'i'-th relocation on this sym to 't'
135 func (sb *SymbolBuilder) SetRelocType(i int, t objabi.RelocType) {
136 sb.relocs[i].SetType(0)
140 // SetRelocSym sets the target sym of the 'i'-th relocation on this sym to 's'
141 func (sb *SymbolBuilder) SetRelocSym(i int, tgt Sym) {
142 sb.relocs[i].SetSym(goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(tgt)})
145 // SetRelocAdd sets the addend of the 'i'-th relocation on this sym to 'a'
146 func (sb *SymbolBuilder) SetRelocAdd(i int, a int64) {
147 sb.relocs[i].SetAdd(a)
150 // Add n relocations, return a handle to the relocations.
151 func (sb *SymbolBuilder) AddRelocs(n int) Relocs {
152 sb.relocs = append(sb.relocs, make([]goobj2.Reloc, n)...)
153 sb.reltypes = append(sb.reltypes, make([]objabi.RelocType, n)...)
154 return sb.l.Relocs(sb.symIdx)
157 // Add a relocation with given type, return its handle and index
158 // (to set other fields).
159 func (sb *SymbolBuilder) AddRel(typ objabi.RelocType) (Reloc2, int) {
161 sb.relocs = append(sb.relocs, goobj2.Reloc{})
162 sb.reltypes = append(sb.reltypes, typ)
163 relocs := sb.Relocs()
164 return relocs.At2(j), j
167 // Sort relocations by offset.
168 func (sb *SymbolBuilder) SortRelocs() {
169 sort.Sort((*relocsByOff)(sb.extSymPayload))
172 // Implement sort.Interface
173 type relocsByOff extSymPayload
175 func (p *relocsByOff) Len() int { return len(p.relocs) }
176 func (p *relocsByOff) Less(i, j int) bool { return p.relocs[i].Off() < p.relocs[j].Off() }
177 func (p *relocsByOff) Swap(i, j int) {
178 p.relocs[i], p.relocs[j] = p.relocs[j], p.relocs[i]
179 p.reltypes[i], p.reltypes[j] = p.reltypes[j], p.reltypes[i]
182 // AddReloc appends the specified reloc to the symbols list of
183 // relocations. Return value is the index of the newly created
185 func (sb *SymbolBuilder) AddReloc(r Reloc) uint32 {
186 // Populate a goobj2.Reloc from external reloc record.
187 rval := uint32(len(sb.relocs))
189 b.Set(r.Off, r.Size, 0, r.Add, goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(r.Sym)})
190 sb.relocs = append(sb.relocs, b)
191 sb.reltypes = append(sb.reltypes, r.Type)
195 // Update the j-th relocation in place.
196 func (sb *SymbolBuilder) SetReloc(j int, r Reloc) {
197 // Populate a goobj2.Reloc from external reloc record.
198 sb.relocs[j].Set(r.Off, r.Size, 0, r.Add, goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(r.Sym)})
199 sb.reltypes[j] = r.Type
202 func (sb *SymbolBuilder) Reachable() bool {
203 return sb.l.AttrReachable(sb.symIdx)
206 func (sb *SymbolBuilder) SetReachable(v bool) {
207 sb.l.SetAttrReachable(sb.symIdx, v)
210 func (sb *SymbolBuilder) setReachable() {
211 sb.SetReachable(true)
214 func (sb *SymbolBuilder) ReadOnly() bool {
215 return sb.l.AttrReadOnly(sb.symIdx)
218 func (sb *SymbolBuilder) SetReadOnly(v bool) {
219 sb.l.SetAttrReadOnly(sb.symIdx, v)
222 func (sb *SymbolBuilder) DuplicateOK() bool {
223 return sb.l.AttrDuplicateOK(sb.symIdx)
226 func (sb *SymbolBuilder) SetDuplicateOK(v bool) {
227 sb.l.SetAttrDuplicateOK(sb.symIdx, v)
230 func (sb *SymbolBuilder) Outer() Sym {
231 return sb.l.OuterSym(sb.symIdx)
234 func (sb *SymbolBuilder) Sub() Sym {
235 return sb.l.SubSym(sb.symIdx)
238 func (sb *SymbolBuilder) SortSub() {
239 sb.l.SortSub(sb.symIdx)
242 func (sb *SymbolBuilder) PrependSub(sub Sym) {
243 sb.l.PrependSub(sb.symIdx, sub)
246 func (sb *SymbolBuilder) AddUint8(v uint8) int64 {
253 sb.data = append(sb.data, v)
257 func (sb *SymbolBuilder) AddUintXX(arch *sys.Arch, v uint64, wid int) int64 {
260 sb.setUintXX(arch, off, v, int64(wid))
264 func (sb *SymbolBuilder) setUintXX(arch *sys.Arch, off int64, v uint64, wid int64) int64 {
268 if sb.size < off+wid {
275 sb.data[off] = uint8(v)
277 arch.ByteOrder.PutUint16(sb.data[off:], uint16(v))
279 arch.ByteOrder.PutUint32(sb.data[off:], uint32(v))
281 arch.ByteOrder.PutUint64(sb.data[off:], v)
287 func (sb *SymbolBuilder) AddUint16(arch *sys.Arch, v uint16) int64 {
288 return sb.AddUintXX(arch, uint64(v), 2)
291 func (sb *SymbolBuilder) AddUint32(arch *sys.Arch, v uint32) int64 {
292 return sb.AddUintXX(arch, uint64(v), 4)
295 func (sb *SymbolBuilder) AddUint64(arch *sys.Arch, v uint64) int64 {
296 return sb.AddUintXX(arch, v, 8)
299 func (sb *SymbolBuilder) AddUint(arch *sys.Arch, v uint64) int64 {
300 return sb.AddUintXX(arch, v, arch.PtrSize)
303 func (sb *SymbolBuilder) SetUint8(arch *sys.Arch, r int64, v uint8) int64 {
305 return sb.setUintXX(arch, r, uint64(v), 1)
308 func (sb *SymbolBuilder) SetUint16(arch *sys.Arch, r int64, v uint16) int64 {
310 return sb.setUintXX(arch, r, uint64(v), 2)
313 func (sb *SymbolBuilder) SetUint32(arch *sys.Arch, r int64, v uint32) int64 {
315 return sb.setUintXX(arch, r, uint64(v), 4)
318 func (sb *SymbolBuilder) SetUint(arch *sys.Arch, r int64, v uint64) int64 {
320 return sb.setUintXX(arch, r, v, int64(arch.PtrSize))
323 func (sb *SymbolBuilder) SetAddrPlus(arch *sys.Arch, off int64, tgt Sym, add int64) int64 {
325 sb.SetType(sym.SDATA)
328 if off+int64(arch.PtrSize) > sb.size {
329 sb.size = off + int64(arch.PtrSize)
335 r.Size = uint8(arch.PtrSize)
336 r.Type = objabi.R_ADDR
339 return off + int64(r.Size)
342 func (sb *SymbolBuilder) SetAddr(arch *sys.Arch, off int64, tgt Sym) int64 {
343 return sb.SetAddrPlus(arch, off, tgt, 0)
346 func (sb *SymbolBuilder) Addstring(str string) int64 {
349 sb.kind = sym.SNOPTRDATA
352 if sb.name == ".shstrtab" {
353 // FIXME: find a better mechanism for this
354 sb.l.elfsetstring(str, int(r))
356 sb.data = append(sb.data, str...)
357 sb.data = append(sb.data, 0)
358 sb.size = int64(len(sb.data))
362 func (sb *SymbolBuilder) addSymRef(tgt Sym, add int64, typ objabi.RelocType, rsize int) int64 {
368 sb.size += int64(rsize)
374 r.Size = uint8(rsize)
379 return i + int64(r.Size)
382 // Add a symbol reference (relocation) with given type, addend, and size
383 // (the most generic form).
384 func (sb *SymbolBuilder) AddSymRef(arch *sys.Arch, tgt Sym, add int64, typ objabi.RelocType, rsize int) int64 {
386 return sb.addSymRef(tgt, add, typ, rsize)
389 func (sb *SymbolBuilder) AddAddrPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
391 return sb.addSymRef(tgt, add, objabi.R_ADDR, arch.PtrSize)
394 func (sb *SymbolBuilder) AddAddrPlus4(arch *sys.Arch, tgt Sym, add int64) int64 {
396 return sb.addSymRef(tgt, add, objabi.R_ADDR, 4)
399 func (sb *SymbolBuilder) AddAddr(arch *sys.Arch, tgt Sym) int64 {
400 return sb.AddAddrPlus(arch, tgt, 0)
403 func (sb *SymbolBuilder) AddPCRelPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
405 return sb.addSymRef(tgt, add, objabi.R_PCREL, 4)
408 func (sb *SymbolBuilder) AddCURelativeAddrPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
410 return sb.addSymRef(tgt, add, objabi.R_ADDRCUOFF, arch.PtrSize)
413 func (sb *SymbolBuilder) AddSize(arch *sys.Arch, tgt Sym) int64 {
415 return sb.addSymRef(tgt, 0, objabi.R_SIZE, arch.PtrSize)
418 // GenAddAddrPlusFunc returns a function to be called when capturing
419 // a function symbol's address. In later stages of the link (when
420 // address assignment is done) when doing internal linking and
421 // targeting an executable, we can just emit the address of a function
422 // directly instead of generating a relocation. Clients can call
423 // this function (setting 'internalExec' based on build mode and target)
424 // and then invoke the returned function in roughly the same way that
425 // loader.*SymbolBuilder.AddAddrPlus would be used.
426 func GenAddAddrPlusFunc(internalExec bool) func(s *SymbolBuilder, arch *sys.Arch, tgt Sym, add int64) int64 {
428 return func(s *SymbolBuilder, arch *sys.Arch, tgt Sym, add int64) int64 {
429 if v := s.l.SymValue(tgt); v != 0 {
430 return s.AddUint(arch, uint64(v+add))
432 return s.AddAddrPlus(arch, tgt, add)
435 return (*SymbolBuilder).AddAddrPlus
439 func (sb *SymbolBuilder) MakeWritable() {
441 sb.data = append([]byte(nil), sb.data...)
442 sb.l.SetAttrReadOnly(sb.symIdx, false)