| // Copyright 2019 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package loader |
| |
| import ( |
| "cmd/internal/goobj" |
| "cmd/internal/objabi" |
| "cmd/internal/sys" |
| "cmd/link/internal/sym" |
| "sort" |
| ) |
| |
| // SymbolBuilder is a helper designed to help with the construction |
| // of new symbol contents. |
| type SymbolBuilder struct { |
| *extSymPayload // points to payload being updated |
| symIdx Sym // index of symbol being updated/constructed |
| l *Loader // loader |
| } |
| |
| // MakeSymbolBuilder creates a symbol builder for use in constructing |
| // an entirely new symbol. |
| func (l *Loader) MakeSymbolBuilder(name string) *SymbolBuilder { |
| // for now assume that any new sym is intended to be static |
| symIdx := l.CreateStaticSym(name) |
| sb := &SymbolBuilder{l: l, symIdx: symIdx} |
| sb.extSymPayload = l.getPayload(symIdx) |
| return sb |
| } |
| |
| // MakeSymbolUpdater creates a symbol builder helper for an existing |
| // symbol 'symIdx'. If 'symIdx' is not an external symbol, then create |
| // a clone of it (copy name, properties, etc) fix things up so that |
| // the lookup tables and caches point to the new version, not the old |
| // version. |
| func (l *Loader) MakeSymbolUpdater(symIdx Sym) *SymbolBuilder { |
| if symIdx == 0 { |
| panic("can't update the null symbol") |
| } |
| if !l.IsExternal(symIdx) { |
| // Create a clone with the same name/version/kind etc. |
| l.cloneToExternal(symIdx) |
| } |
| |
| // Construct updater and return. |
| sb := &SymbolBuilder{l: l, symIdx: symIdx} |
| sb.extSymPayload = l.getPayload(symIdx) |
| return sb |
| } |
| |
| // CreateSymForUpdate creates a symbol with given name and version, |
| // returns a CreateSymForUpdate for update. If the symbol already |
| // exists, it will update in-place. |
| func (l *Loader) CreateSymForUpdate(name string, version int) *SymbolBuilder { |
| s := l.LookupOrCreateSym(name, version) |
| l.SetAttrReachable(s, true) |
| return l.MakeSymbolUpdater(s) |
| } |
| |
| // Getters for properties of the symbol we're working on. |
| |
| func (sb *SymbolBuilder) Sym() Sym { return sb.symIdx } |
| func (sb *SymbolBuilder) Name() string { return sb.name } |
| func (sb *SymbolBuilder) Version() int { return sb.ver } |
| func (sb *SymbolBuilder) Type() sym.SymKind { return sb.kind } |
| func (sb *SymbolBuilder) Size() int64 { return sb.size } |
| func (sb *SymbolBuilder) Data() []byte { return sb.data } |
| func (sb *SymbolBuilder) Value() int64 { return sb.l.SymValue(sb.symIdx) } |
| func (sb *SymbolBuilder) Align() int32 { return sb.l.SymAlign(sb.symIdx) } |
| func (sb *SymbolBuilder) Localentry() uint8 { return sb.l.SymLocalentry(sb.symIdx) } |
| func (sb *SymbolBuilder) OnList() bool { return sb.l.AttrOnList(sb.symIdx) } |
| func (sb *SymbolBuilder) External() bool { return sb.l.AttrExternal(sb.symIdx) } |
| func (sb *SymbolBuilder) Extname() string { return sb.l.SymExtname(sb.symIdx) } |
| func (sb *SymbolBuilder) CgoExportDynamic() bool { return sb.l.AttrCgoExportDynamic(sb.symIdx) } |
| func (sb *SymbolBuilder) Dynimplib() string { return sb.l.SymDynimplib(sb.symIdx) } |
| func (sb *SymbolBuilder) Dynimpvers() string { return sb.l.SymDynimpvers(sb.symIdx) } |
| func (sb *SymbolBuilder) SubSym() Sym { return sb.l.SubSym(sb.symIdx) } |
| func (sb *SymbolBuilder) GoType() Sym { return sb.l.SymGoType(sb.symIdx) } |
| func (sb *SymbolBuilder) VisibilityHidden() bool { return sb.l.AttrVisibilityHidden(sb.symIdx) } |
| func (sb *SymbolBuilder) Sect() *sym.Section { return sb.l.SymSect(sb.symIdx) } |
| |
| // Setters for symbol properties. |
| |
| func (sb *SymbolBuilder) SetType(kind sym.SymKind) { sb.kind = kind } |
| func (sb *SymbolBuilder) SetSize(size int64) { sb.size = size } |
| func (sb *SymbolBuilder) SetData(data []byte) { sb.data = data } |
| func (sb *SymbolBuilder) SetOnList(v bool) { sb.l.SetAttrOnList(sb.symIdx, v) } |
| func (sb *SymbolBuilder) SetExternal(v bool) { sb.l.SetAttrExternal(sb.symIdx, v) } |
| func (sb *SymbolBuilder) SetValue(v int64) { sb.l.SetSymValue(sb.symIdx, v) } |
| func (sb *SymbolBuilder) SetAlign(align int32) { sb.l.SetSymAlign(sb.symIdx, align) } |
| func (sb *SymbolBuilder) SetLocalentry(value uint8) { sb.l.SetSymLocalentry(sb.symIdx, value) } |
| func (sb *SymbolBuilder) SetExtname(value string) { sb.l.SetSymExtname(sb.symIdx, value) } |
| func (sb *SymbolBuilder) SetDynimplib(value string) { sb.l.SetSymDynimplib(sb.symIdx, value) } |
| func (sb *SymbolBuilder) SetDynimpvers(value string) { sb.l.SetSymDynimpvers(sb.symIdx, value) } |
| func (sb *SymbolBuilder) SetPlt(value int32) { sb.l.SetPlt(sb.symIdx, value) } |
| func (sb *SymbolBuilder) SetGot(value int32) { sb.l.SetGot(sb.symIdx, value) } |
| func (sb *SymbolBuilder) SetSpecial(value bool) { sb.l.SetAttrSpecial(sb.symIdx, value) } |
| func (sb *SymbolBuilder) SetLocal(value bool) { sb.l.SetAttrLocal(sb.symIdx, value) } |
| func (sb *SymbolBuilder) SetVisibilityHidden(value bool) { |
| sb.l.SetAttrVisibilityHidden(sb.symIdx, value) |
| } |
| func (sb *SymbolBuilder) SetNotInSymbolTable(value bool) { |
| sb.l.SetAttrNotInSymbolTable(sb.symIdx, value) |
| } |
| func (sb *SymbolBuilder) SetSect(sect *sym.Section) { sb.l.SetSymSect(sb.symIdx, sect) } |
| |
| func (sb *SymbolBuilder) AddBytes(data []byte) { |
| if sb.kind == 0 { |
| sb.kind = sym.SDATA |
| } |
| sb.data = append(sb.data, data...) |
| sb.size = int64(len(sb.data)) |
| } |
| |
| func (sb *SymbolBuilder) Relocs() Relocs { |
| return sb.l.Relocs(sb.symIdx) |
| } |
| |
| // ResetRelocs removes all relocations on this symbol. |
| func (sb *SymbolBuilder) ResetRelocs() { |
| sb.relocs = sb.relocs[:0] |
| sb.reltypes = sb.reltypes[:0] |
| } |
| |
| // SetRelocType sets the type of the 'i'-th relocation on this sym to 't' |
| func (sb *SymbolBuilder) SetRelocType(i int, t objabi.RelocType) { |
| sb.relocs[i].SetType(0) |
| sb.reltypes[i] = t |
| } |
| |
| // SetRelocSym sets the target sym of the 'i'-th relocation on this sym to 's' |
| func (sb *SymbolBuilder) SetRelocSym(i int, tgt Sym) { |
| sb.relocs[i].SetSym(goobj.SymRef{PkgIdx: 0, SymIdx: uint32(tgt)}) |
| } |
| |
| // SetRelocAdd sets the addend of the 'i'-th relocation on this sym to 'a' |
| func (sb *SymbolBuilder) SetRelocAdd(i int, a int64) { |
| sb.relocs[i].SetAdd(a) |
| } |
| |
| // Add n relocations, return a handle to the relocations. |
| func (sb *SymbolBuilder) AddRelocs(n int) Relocs { |
| sb.relocs = append(sb.relocs, make([]goobj.Reloc, n)...) |
| sb.reltypes = append(sb.reltypes, make([]objabi.RelocType, n)...) |
| return sb.l.Relocs(sb.symIdx) |
| } |
| |
| // Add a relocation with given type, return its handle and index |
| // (to set other fields). |
| func (sb *SymbolBuilder) AddRel(typ objabi.RelocType) (Reloc, int) { |
| j := len(sb.relocs) |
| sb.relocs = append(sb.relocs, goobj.Reloc{}) |
| sb.reltypes = append(sb.reltypes, typ) |
| relocs := sb.Relocs() |
| return relocs.At(j), j |
| } |
| |
| // Sort relocations by offset. |
| func (sb *SymbolBuilder) SortRelocs() { |
| sort.Sort((*relocsByOff)(sb.extSymPayload)) |
| } |
| |
| // Implement sort.Interface |
| type relocsByOff extSymPayload |
| |
| func (p *relocsByOff) Len() int { return len(p.relocs) } |
| func (p *relocsByOff) Less(i, j int) bool { return p.relocs[i].Off() < p.relocs[j].Off() } |
| func (p *relocsByOff) Swap(i, j int) { |
| p.relocs[i], p.relocs[j] = p.relocs[j], p.relocs[i] |
| p.reltypes[i], p.reltypes[j] = p.reltypes[j], p.reltypes[i] |
| } |
| |
| func (sb *SymbolBuilder) Reachable() bool { |
| return sb.l.AttrReachable(sb.symIdx) |
| } |
| |
| func (sb *SymbolBuilder) SetReachable(v bool) { |
| sb.l.SetAttrReachable(sb.symIdx, v) |
| } |
| |
| func (sb *SymbolBuilder) setReachable() { |
| sb.SetReachable(true) |
| } |
| |
| func (sb *SymbolBuilder) ReadOnly() bool { |
| return sb.l.AttrReadOnly(sb.symIdx) |
| } |
| |
| func (sb *SymbolBuilder) SetReadOnly(v bool) { |
| sb.l.SetAttrReadOnly(sb.symIdx, v) |
| } |
| |
| func (sb *SymbolBuilder) DuplicateOK() bool { |
| return sb.l.AttrDuplicateOK(sb.symIdx) |
| } |
| |
| func (sb *SymbolBuilder) SetDuplicateOK(v bool) { |
| sb.l.SetAttrDuplicateOK(sb.symIdx, v) |
| } |
| |
| func (sb *SymbolBuilder) Outer() Sym { |
| return sb.l.OuterSym(sb.symIdx) |
| } |
| |
| func (sb *SymbolBuilder) Sub() Sym { |
| return sb.l.SubSym(sb.symIdx) |
| } |
| |
| func (sb *SymbolBuilder) SortSub() { |
| sb.l.SortSub(sb.symIdx) |
| } |
| |
| func (sb *SymbolBuilder) AddInteriorSym(sub Sym) { |
| sb.l.AddInteriorSym(sb.symIdx, sub) |
| } |
| |
| func (sb *SymbolBuilder) AddUint8(v uint8) int64 { |
| off := sb.size |
| if sb.kind == 0 { |
| sb.kind = sym.SDATA |
| } |
| sb.size++ |
| sb.data = append(sb.data, v) |
| return off |
| } |
| |
| func (sb *SymbolBuilder) AddUintXX(arch *sys.Arch, v uint64, wid int) int64 { |
| off := sb.size |
| sb.setUintXX(arch, off, v, int64(wid)) |
| return off |
| } |
| |
| func (sb *SymbolBuilder) setUintXX(arch *sys.Arch, off int64, v uint64, wid int64) int64 { |
| if sb.kind == 0 { |
| sb.kind = sym.SDATA |
| } |
| if sb.size < off+wid { |
| sb.size = off + wid |
| sb.Grow(sb.size) |
| } |
| |
| switch wid { |
| case 1: |
| sb.data[off] = uint8(v) |
| case 2: |
| arch.ByteOrder.PutUint16(sb.data[off:], uint16(v)) |
| case 4: |
| arch.ByteOrder.PutUint32(sb.data[off:], uint32(v)) |
| case 8: |
| arch.ByteOrder.PutUint64(sb.data[off:], v) |
| } |
| |
| return off + wid |
| } |
| |
| func (sb *SymbolBuilder) AddUint16(arch *sys.Arch, v uint16) int64 { |
| return sb.AddUintXX(arch, uint64(v), 2) |
| } |
| |
| func (sb *SymbolBuilder) AddUint32(arch *sys.Arch, v uint32) int64 { |
| return sb.AddUintXX(arch, uint64(v), 4) |
| } |
| |
| func (sb *SymbolBuilder) AddUint64(arch *sys.Arch, v uint64) int64 { |
| return sb.AddUintXX(arch, v, 8) |
| } |
| |
| func (sb *SymbolBuilder) AddUint(arch *sys.Arch, v uint64) int64 { |
| return sb.AddUintXX(arch, v, arch.PtrSize) |
| } |
| |
| func (sb *SymbolBuilder) SetUint8(arch *sys.Arch, r int64, v uint8) int64 { |
| return sb.setUintXX(arch, r, uint64(v), 1) |
| } |
| |
| func (sb *SymbolBuilder) SetUint16(arch *sys.Arch, r int64, v uint16) int64 { |
| return sb.setUintXX(arch, r, uint64(v), 2) |
| } |
| |
| func (sb *SymbolBuilder) SetUint32(arch *sys.Arch, r int64, v uint32) int64 { |
| return sb.setUintXX(arch, r, uint64(v), 4) |
| } |
| |
| func (sb *SymbolBuilder) SetUint(arch *sys.Arch, r int64, v uint64) int64 { |
| return sb.setUintXX(arch, r, v, int64(arch.PtrSize)) |
| } |
| |
| func (sb *SymbolBuilder) SetUintptr(arch *sys.Arch, r int64, v uintptr) int64 { |
| return sb.setUintXX(arch, r, uint64(v), int64(arch.PtrSize)) |
| } |
| |
| func (sb *SymbolBuilder) SetAddrPlus(arch *sys.Arch, off int64, tgt Sym, add int64) int64 { |
| if sb.Type() == 0 { |
| sb.SetType(sym.SDATA) |
| } |
| if off+int64(arch.PtrSize) > sb.size { |
| sb.size = off + int64(arch.PtrSize) |
| sb.Grow(sb.size) |
| } |
| r, _ := sb.AddRel(objabi.R_ADDR) |
| r.SetSym(tgt) |
| r.SetOff(int32(off)) |
| r.SetSiz(uint8(arch.PtrSize)) |
| r.SetAdd(add) |
| return off + int64(r.Siz()) |
| } |
| |
| func (sb *SymbolBuilder) SetAddr(arch *sys.Arch, off int64, tgt Sym) int64 { |
| return sb.SetAddrPlus(arch, off, tgt, 0) |
| } |
| |
| func (sb *SymbolBuilder) AddStringAt(off int64, str string) int64 { |
| strLen := int64(len(str)) |
| if off+strLen+1 > int64(len(sb.data)) { |
| panic("attempt to write past end of buffer") |
| } |
| copy(sb.data[off:off+strLen], str) |
| sb.data[off+strLen] = 0 |
| return off + strLen + 1 |
| } |
| |
| func (sb *SymbolBuilder) Addstring(str string) int64 { |
| if sb.kind == 0 { |
| sb.kind = sym.SNOPTRDATA |
| } |
| r := sb.size |
| if sb.name == ".shstrtab" { |
| // FIXME: find a better mechanism for this |
| sb.l.elfsetstring(str, int(r)) |
| } |
| sb.data = append(sb.data, str...) |
| sb.data = append(sb.data, 0) |
| sb.size = int64(len(sb.data)) |
| return r |
| } |
| |
| func (sb *SymbolBuilder) SetBytesAt(off int64, b []byte) int64 { |
| datLen := int64(len(b)) |
| if off+datLen > int64(len(sb.data)) { |
| panic("attempt to write past end of buffer") |
| } |
| copy(sb.data[off:off+datLen], b) |
| return off + datLen |
| } |
| |
| func (sb *SymbolBuilder) addSymRef(tgt Sym, add int64, typ objabi.RelocType, rsize int) int64 { |
| if sb.kind == 0 { |
| sb.kind = sym.SDATA |
| } |
| i := sb.size |
| |
| sb.size += int64(rsize) |
| sb.Grow(sb.size) |
| |
| r, _ := sb.AddRel(typ) |
| r.SetSym(tgt) |
| r.SetOff(int32(i)) |
| r.SetSiz(uint8(rsize)) |
| r.SetAdd(add) |
| |
| return i + int64(rsize) |
| } |
| |
| // Add a symbol reference (relocation) with given type, addend, and size |
| // (the most generic form). |
| func (sb *SymbolBuilder) AddSymRef(arch *sys.Arch, tgt Sym, add int64, typ objabi.RelocType, rsize int) int64 { |
| return sb.addSymRef(tgt, add, typ, rsize) |
| } |
| |
| func (sb *SymbolBuilder) AddAddrPlus(arch *sys.Arch, tgt Sym, add int64) int64 { |
| return sb.addSymRef(tgt, add, objabi.R_ADDR, arch.PtrSize) |
| } |
| |
| func (sb *SymbolBuilder) AddAddrPlus4(arch *sys.Arch, tgt Sym, add int64) int64 { |
| return sb.addSymRef(tgt, add, objabi.R_ADDR, 4) |
| } |
| |
| func (sb *SymbolBuilder) AddAddr(arch *sys.Arch, tgt Sym) int64 { |
| return sb.AddAddrPlus(arch, tgt, 0) |
| } |
| |
| func (sb *SymbolBuilder) AddPCRelPlus(arch *sys.Arch, tgt Sym, add int64) int64 { |
| return sb.addSymRef(tgt, add, objabi.R_PCREL, 4) |
| } |
| |
| func (sb *SymbolBuilder) AddCURelativeAddrPlus(arch *sys.Arch, tgt Sym, add int64) int64 { |
| return sb.addSymRef(tgt, add, objabi.R_ADDRCUOFF, arch.PtrSize) |
| } |
| |
| func (sb *SymbolBuilder) AddSize(arch *sys.Arch, tgt Sym) int64 { |
| return sb.addSymRef(tgt, 0, objabi.R_SIZE, arch.PtrSize) |
| } |
| |
| // GenAddAddrPlusFunc returns a function to be called when capturing |
| // a function symbol's address. In later stages of the link (when |
| // address assignment is done) when doing internal linking and |
| // targeting an executable, we can just emit the address of a function |
| // directly instead of generating a relocation. Clients can call |
| // this function (setting 'internalExec' based on build mode and target) |
| // and then invoke the returned function in roughly the same way that |
| // loader.*SymbolBuilder.AddAddrPlus would be used. |
| func GenAddAddrPlusFunc(internalExec bool) func(s *SymbolBuilder, arch *sys.Arch, tgt Sym, add int64) int64 { |
| if internalExec { |
| return func(s *SymbolBuilder, arch *sys.Arch, tgt Sym, add int64) int64 { |
| if v := s.l.SymValue(tgt); v != 0 { |
| return s.AddUint(arch, uint64(v+add)) |
| } |
| return s.AddAddrPlus(arch, tgt, add) |
| } |
| } else { |
| return (*SymbolBuilder).AddAddrPlus |
| } |
| } |
| |
| func (sb *SymbolBuilder) MakeWritable() { |
| if sb.ReadOnly() { |
| sb.data = append([]byte(nil), sb.data...) |
| sb.l.SetAttrReadOnly(sb.symIdx, false) |
| } |
| } |
| |
| func (sb *SymbolBuilder) AddUleb(v uint64) { |
| if v < 128 { // common case: 1 byte |
| sb.AddUint8(uint8(v)) |
| return |
| } |
| for { |
| c := uint8(v & 0x7f) |
| v >>= 7 |
| if v != 0 { |
| c |= 0x80 |
| } |
| sb.AddUint8(c) |
| if c&0x80 == 0 { |
| break |
| } |
| } |
| } |
