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 s := l.LookupOrCreateSym(name, version)
58 l.SetAttrReachable(s, true)
59 return l.MakeSymbolUpdater(s)
62 // Getters for properties of the symbol we're working on.
64 func (sb *SymbolBuilder) Sym() Sym { return sb.symIdx }
65 func (sb *SymbolBuilder) Name() string { return sb.name }
66 func (sb *SymbolBuilder) Version() int { return sb.ver }
67 func (sb *SymbolBuilder) Type() sym.SymKind { return sb.kind }
68 func (sb *SymbolBuilder) Size() int64 { return sb.size }
69 func (sb *SymbolBuilder) Data() []byte { return sb.data }
70 func (sb *SymbolBuilder) Value() int64 { return sb.l.SymValue(sb.symIdx) }
71 func (sb *SymbolBuilder) Align() int32 { return sb.l.SymAlign(sb.symIdx) }
72 func (sb *SymbolBuilder) Localentry() uint8 { return sb.l.SymLocalentry(sb.symIdx) }
73 func (sb *SymbolBuilder) OnList() bool { return sb.l.AttrOnList(sb.symIdx) }
74 func (sb *SymbolBuilder) External() bool { return sb.l.AttrExternal(sb.symIdx) }
75 func (sb *SymbolBuilder) Extname() string { return sb.l.SymExtname(sb.symIdx) }
76 func (sb *SymbolBuilder) CgoExportDynamic() bool { return sb.l.AttrCgoExportDynamic(sb.symIdx) }
77 func (sb *SymbolBuilder) Dynimplib() string { return sb.l.SymDynimplib(sb.symIdx) }
78 func (sb *SymbolBuilder) Dynimpvers() string { return sb.l.SymDynimpvers(sb.symIdx) }
79 func (sb *SymbolBuilder) SubSym() Sym { return sb.l.SubSym(sb.symIdx) }
80 func (sb *SymbolBuilder) GoType() Sym { return sb.l.SymGoType(sb.symIdx) }
81 func (sb *SymbolBuilder) VisibilityHidden() bool { return sb.l.AttrVisibilityHidden(sb.symIdx) }
82 func (sb *SymbolBuilder) Sect() *sym.Section { return sb.l.SymSect(sb.symIdx) }
84 // Setters for symbol properties.
86 func (sb *SymbolBuilder) SetType(kind sym.SymKind) { sb.kind = kind }
87 func (sb *SymbolBuilder) SetSize(size int64) { sb.size = size }
88 func (sb *SymbolBuilder) SetData(data []byte) { sb.data = data }
89 func (sb *SymbolBuilder) SetOnList(v bool) { sb.l.SetAttrOnList(sb.symIdx, v) }
90 func (sb *SymbolBuilder) SetExternal(v bool) { sb.l.SetAttrExternal(sb.symIdx, v) }
91 func (sb *SymbolBuilder) SetValue(v int64) { sb.l.SetSymValue(sb.symIdx, v) }
92 func (sb *SymbolBuilder) SetAlign(align int32) { sb.l.SetSymAlign(sb.symIdx, align) }
93 func (sb *SymbolBuilder) SetLocalentry(value uint8) { sb.l.SetSymLocalentry(sb.symIdx, value) }
94 func (sb *SymbolBuilder) SetExtname(value string) { sb.l.SetSymExtname(sb.symIdx, value) }
95 func (sb *SymbolBuilder) SetDynimplib(value string) { sb.l.SetSymDynimplib(sb.symIdx, value) }
96 func (sb *SymbolBuilder) SetDynimpvers(value string) { sb.l.SetSymDynimpvers(sb.symIdx, value) }
97 func (sb *SymbolBuilder) SetPlt(value int32) { sb.l.SetPlt(sb.symIdx, value) }
98 func (sb *SymbolBuilder) SetGot(value int32) { sb.l.SetGot(sb.symIdx, value) }
99 func (sb *SymbolBuilder) SetSpecial(value bool) { sb.l.SetAttrSpecial(sb.symIdx, value) }
100 func (sb *SymbolBuilder) SetLocal(value bool) { sb.l.SetAttrLocal(sb.symIdx, value) }
101 func (sb *SymbolBuilder) SetVisibilityHidden(value bool) {
102 sb.l.SetAttrVisibilityHidden(sb.symIdx, value)
104 func (sb *SymbolBuilder) SetNotInSymbolTable(value bool) {
105 sb.l.SetAttrNotInSymbolTable(sb.symIdx, value)
107 func (sb *SymbolBuilder) SetSect(sect *sym.Section) { sb.l.SetSymSect(sb.symIdx, sect) }
109 func (sb *SymbolBuilder) AddBytes(data []byte) {
113 sb.data = append(sb.data, data...)
114 sb.size = int64(len(sb.data))
117 func (sb *SymbolBuilder) Relocs() Relocs {
118 return sb.l.Relocs(sb.symIdx)
121 // ResetRelocs removes all relocations on this symbol.
122 func (sb *SymbolBuilder) ResetRelocs() {
123 sb.relocs = sb.relocs[:0]
126 // SetRelocType sets the type of the 'i'-th relocation on this sym to 't'
127 func (sb *SymbolBuilder) SetRelocType(i int, t objabi.RelocType) {
128 sb.relocs[i].SetType(uint16(t))
131 // SetRelocSym sets the target sym of the 'i'-th relocation on this sym to 's'
132 func (sb *SymbolBuilder) SetRelocSym(i int, tgt Sym) {
133 sb.relocs[i].SetSym(goobj.SymRef{PkgIdx: 0, SymIdx: uint32(tgt)})
136 // SetRelocAdd sets the addend of the 'i'-th relocation on this sym to 'a'
137 func (sb *SymbolBuilder) SetRelocAdd(i int, a int64) {
138 sb.relocs[i].SetAdd(a)
141 // Add n relocations, return a handle to the relocations.
142 func (sb *SymbolBuilder) AddRelocs(n int) Relocs {
143 sb.relocs = append(sb.relocs, make([]goobj.Reloc, n)...)
144 return sb.l.Relocs(sb.symIdx)
147 // Add a relocation with given type, return its handle and index
148 // (to set other fields).
149 func (sb *SymbolBuilder) AddRel(typ objabi.RelocType) (Reloc, int) {
151 sb.relocs = append(sb.relocs, goobj.Reloc{})
152 sb.relocs[j].SetType(uint16(typ))
153 relocs := sb.Relocs()
154 return relocs.At(j), j
157 // Sort relocations by offset.
158 func (sb *SymbolBuilder) SortRelocs() {
159 sort.Sort((*relocsByOff)(sb.extSymPayload))
162 // Implement sort.Interface
163 type relocsByOff extSymPayload
165 func (p *relocsByOff) Len() int { return len(p.relocs) }
166 func (p *relocsByOff) Less(i, j int) bool { return p.relocs[i].Off() < p.relocs[j].Off() }
167 func (p *relocsByOff) Swap(i, j int) {
168 p.relocs[i], p.relocs[j] = p.relocs[j], p.relocs[i]
171 func (sb *SymbolBuilder) Reachable() bool {
172 return sb.l.AttrReachable(sb.symIdx)
175 func (sb *SymbolBuilder) SetReachable(v bool) {
176 sb.l.SetAttrReachable(sb.symIdx, v)
179 func (sb *SymbolBuilder) setReachable() {
180 sb.SetReachable(true)
183 func (sb *SymbolBuilder) ReadOnly() bool {
184 return sb.l.AttrReadOnly(sb.symIdx)
187 func (sb *SymbolBuilder) SetReadOnly(v bool) {
188 sb.l.SetAttrReadOnly(sb.symIdx, v)
191 func (sb *SymbolBuilder) DuplicateOK() bool {
192 return sb.l.AttrDuplicateOK(sb.symIdx)
195 func (sb *SymbolBuilder) SetDuplicateOK(v bool) {
196 sb.l.SetAttrDuplicateOK(sb.symIdx, v)
199 func (sb *SymbolBuilder) Outer() Sym {
200 return sb.l.OuterSym(sb.symIdx)
203 func (sb *SymbolBuilder) Sub() Sym {
204 return sb.l.SubSym(sb.symIdx)
207 func (sb *SymbolBuilder) SortSub() {
208 sb.l.SortSub(sb.symIdx)
211 func (sb *SymbolBuilder) AddInteriorSym(sub Sym) {
212 sb.l.AddInteriorSym(sb.symIdx, sub)
215 func (sb *SymbolBuilder) AddUint8(v uint8) int64 {
221 sb.data = append(sb.data, v)
225 func (sb *SymbolBuilder) AddUintXX(arch *sys.Arch, v uint64, wid int) int64 {
227 sb.setUintXX(arch, off, v, int64(wid))
231 func (sb *SymbolBuilder) setUintXX(arch *sys.Arch, off int64, v uint64, wid int64) int64 {
235 if sb.size < off+wid {
242 sb.data[off] = uint8(v)
244 arch.ByteOrder.PutUint16(sb.data[off:], uint16(v))
246 arch.ByteOrder.PutUint32(sb.data[off:], uint32(v))
248 arch.ByteOrder.PutUint64(sb.data[off:], v)
254 func (sb *SymbolBuilder) AddUint16(arch *sys.Arch, v uint16) int64 {
255 return sb.AddUintXX(arch, uint64(v), 2)
258 func (sb *SymbolBuilder) AddUint32(arch *sys.Arch, v uint32) int64 {
259 return sb.AddUintXX(arch, uint64(v), 4)
262 func (sb *SymbolBuilder) AddUint64(arch *sys.Arch, v uint64) int64 {
263 return sb.AddUintXX(arch, v, 8)
266 func (sb *SymbolBuilder) AddUint(arch *sys.Arch, v uint64) int64 {
267 return sb.AddUintXX(arch, v, arch.PtrSize)
270 func (sb *SymbolBuilder) SetUint8(arch *sys.Arch, r int64, v uint8) int64 {
271 return sb.setUintXX(arch, r, uint64(v), 1)
274 func (sb *SymbolBuilder) SetUint16(arch *sys.Arch, r int64, v uint16) int64 {
275 return sb.setUintXX(arch, r, uint64(v), 2)
278 func (sb *SymbolBuilder) SetUint32(arch *sys.Arch, r int64, v uint32) int64 {
279 return sb.setUintXX(arch, r, uint64(v), 4)
282 func (sb *SymbolBuilder) SetUint(arch *sys.Arch, r int64, v uint64) int64 {
283 return sb.setUintXX(arch, r, v, int64(arch.PtrSize))
286 func (sb *SymbolBuilder) SetUintptr(arch *sys.Arch, r int64, v uintptr) int64 {
287 return sb.setUintXX(arch, r, uint64(v), int64(arch.PtrSize))
290 func (sb *SymbolBuilder) SetAddrPlus(arch *sys.Arch, off int64, tgt Sym, add int64) int64 {
292 sb.SetType(sym.SDATA)
294 if off+int64(arch.PtrSize) > sb.size {
295 sb.size = off + int64(arch.PtrSize)
298 r, _ := sb.AddRel(objabi.R_ADDR)
301 r.SetSiz(uint8(arch.PtrSize))
303 return off + int64(r.Siz())
306 func (sb *SymbolBuilder) SetAddr(arch *sys.Arch, off int64, tgt Sym) int64 {
307 return sb.SetAddrPlus(arch, off, tgt, 0)
310 func (sb *SymbolBuilder) AddStringAt(off int64, str string) int64 {
311 strLen := int64(len(str))
312 if off+strLen+1 > int64(len(sb.data)) {
313 panic("attempt to write past end of buffer")
315 copy(sb.data[off:off+strLen], str)
316 sb.data[off+strLen] = 0
317 return off + strLen + 1
320 func (sb *SymbolBuilder) Addstring(str string) int64 {
322 sb.kind = sym.SNOPTRDATA
325 if sb.name == ".shstrtab" {
326 // FIXME: find a better mechanism for this
327 sb.l.elfsetstring(str, int(r))
329 sb.data = append(sb.data, str...)
330 sb.data = append(sb.data, 0)
331 sb.size = int64(len(sb.data))
335 func (sb *SymbolBuilder) SetBytesAt(off int64, b []byte) int64 {
336 datLen := int64(len(b))
337 if off+datLen > int64(len(sb.data)) {
338 panic("attempt to write past end of buffer")
340 copy(sb.data[off:off+datLen], b)
344 func (sb *SymbolBuilder) addSymRef(tgt Sym, add int64, typ objabi.RelocType, rsize int) int64 {
350 sb.size += int64(rsize)
353 r, _ := sb.AddRel(typ)
356 r.SetSiz(uint8(rsize))
359 return i + int64(rsize)
362 // Add a symbol reference (relocation) with given type, addend, and size
363 // (the most generic form).
364 func (sb *SymbolBuilder) AddSymRef(arch *sys.Arch, tgt Sym, add int64, typ objabi.RelocType, rsize int) int64 {
365 return sb.addSymRef(tgt, add, typ, rsize)
368 func (sb *SymbolBuilder) AddAddrPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
369 return sb.addSymRef(tgt, add, objabi.R_ADDR, arch.PtrSize)
372 func (sb *SymbolBuilder) AddAddrPlus4(arch *sys.Arch, tgt Sym, add int64) int64 {
373 return sb.addSymRef(tgt, add, objabi.R_ADDR, 4)
376 func (sb *SymbolBuilder) AddAddr(arch *sys.Arch, tgt Sym) int64 {
377 return sb.AddAddrPlus(arch, tgt, 0)
380 func (sb *SymbolBuilder) AddPCRelPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
381 return sb.addSymRef(tgt, add, objabi.R_PCREL, 4)
384 func (sb *SymbolBuilder) AddCURelativeAddrPlus(arch *sys.Arch, tgt Sym, add int64) int64 {
385 return sb.addSymRef(tgt, add, objabi.R_ADDRCUOFF, arch.PtrSize)
388 func (sb *SymbolBuilder) AddSize(arch *sys.Arch, tgt Sym) int64 {
389 return sb.addSymRef(tgt, 0, objabi.R_SIZE, arch.PtrSize)
392 // GenAddAddrPlusFunc returns a function to be called when capturing
393 // a function symbol's address. In later stages of the link (when
394 // address assignment is done) when doing internal linking and
395 // targeting an executable, we can just emit the address of a function
396 // directly instead of generating a relocation. Clients can call
397 // this function (setting 'internalExec' based on build mode and target)
398 // and then invoke the returned function in roughly the same way that
399 // loader.*SymbolBuilder.AddAddrPlus would be used.
400 func GenAddAddrPlusFunc(internalExec bool) func(s *SymbolBuilder, arch *sys.Arch, tgt Sym, add int64) int64 {
402 return func(s *SymbolBuilder, arch *sys.Arch, tgt Sym, add int64) int64 {
403 if v := s.l.SymValue(tgt); v != 0 {
404 return s.AddUint(arch, uint64(v+add))
406 return s.AddAddrPlus(arch, tgt, add)
409 return (*SymbolBuilder).AddAddrPlus
413 func (sb *SymbolBuilder) MakeWritable() {
415 sb.data = append([]byte(nil), sb.data...)
416 sb.l.SetAttrReadOnly(sb.symIdx, false)
420 func (sb *SymbolBuilder) AddUleb(v uint64) {
421 if v < 128 { // common case: 1 byte
422 sb.AddUint8(uint8(v))