diff options
Diffstat (limited to 'src/cmd/internal/obj/objfile.go')
| -rw-r--r-- | src/cmd/internal/obj/objfile.go | 127 |
1 files changed, 11 insertions, 116 deletions
diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go index 2e9e65a99f..d83ccca9a6 100644 --- a/src/cmd/internal/obj/objfile.go +++ b/src/cmd/internal/obj/objfile.go @@ -3,118 +3,13 @@ // license that can be found in the LICENSE file. // Writing of Go object files. -// -// Originally, Go object files were Plan 9 object files, but no longer. -// Now they are more like standard object files, in that each symbol is defined -// by an associated memory image (bytes) and a list of relocations to apply -// during linking. We do not (yet?) use a standard file format, however. -// For now, the format is chosen to be as simple as possible to read and write. -// It may change for reasons of efficiency, or we may even switch to a -// standard file format if there are compelling benefits to doing so. -// See golang.org/s/go13linker for more background. -// -// The file format is: -// -// - magic header: "\x00\x00go19ld" -// - byte 1 - version number -// - sequence of strings giving dependencies (imported packages) -// - empty string (marks end of sequence) -// - sequence of symbol references used by the defined symbols -// - byte 0xff (marks end of sequence) -// - sequence of integer lengths: -// - total data length -// - total number of relocations -// - total number of pcdata -// - total number of automatics -// - total number of funcdata -// - total number of files -// - data, the content of the defined symbols -// - sequence of defined symbols -// - byte 0xff (marks end of sequence) -// - magic footer: "\xff\xffgo19ld" -// -// All integers are stored in a zigzag varint format. -// See golang.org/s/go12symtab for a definition. -// -// Data blocks and strings are both stored as an integer -// followed by that many bytes. -// -// A symbol reference is a string name followed by a version. -// -// A symbol points to other symbols using an index into the symbol -// reference sequence. Index 0 corresponds to a nil LSym* pointer. -// In the symbol layout described below "symref index" stands for this -// index. -// -// Each symbol is laid out as the following fields (taken from LSym*): -// -// - byte 0xfe (sanity check for synchronization) -// - type [int] -// - name & version [symref index] -// - flags [int] -// 1<<0 dupok -// 1<<1 local -// 1<<2 add to typelink table -// - size [int] -// - gotype [symref index] -// - p [data block] -// - nr [int] -// - r [nr relocations, sorted by off] -// -// If type == STEXT, there are a few more fields: -// -// - args [int] -// - locals [int] -// - nosplit [int] -// - flags [int] -// 1<<0 leaf -// 1<<1 C function -// 1<<2 function may call reflect.Type.Method -// - nlocal [int] -// - local [nlocal automatics] -// - pcln [pcln table] -// -// Each relocation has the encoding: -// -// - off [int] -// - siz [int] -// - type [int] -// - add [int] -// - sym [symref index] -// -// Each local has the encoding: -// -// - asym [symref index] -// - offset [int] -// - type [int] -// - gotype [symref index] -// -// The pcln table has the encoding: -// -// - pcsp [data block] -// - pcfile [data block] -// - pcline [data block] -// - pcinline [data block] -// - npcdata [int] -// - pcdata [npcdata data blocks] -// - nfuncdata [int] -// - funcdata [nfuncdata symref index] -// - funcdatasym [nfuncdata ints] -// - nfile [int] -// - file [nfile symref index] -// - ninlinedcall [int] -// - inlinedcall [ninlinedcall int symref int symref] -// -// The file layout and meaning of type integers are architecture-independent. -// -// TODO(rsc): The file format is good for a first pass but needs work. -// - There are SymID in the object file that should really just be strings. package obj import ( "bufio" "cmd/internal/dwarf" + "cmd/internal/objabi" "cmd/internal/sys" "fmt" "log" @@ -149,7 +44,7 @@ func (w *objWriter) addLengths(s *LSym) { w.nData += len(s.P) w.nReloc += len(s.R) - if s.Type != STEXT { + if s.Type != objabi.STEXT { return } @@ -289,7 +184,7 @@ func (w *objWriter) writeRefs(s *LSym) { w.writeRef(s.R[i].Sym, false) } - if s.Type == STEXT { + if s.Type == objabi.STEXT { for _, a := range s.Func.Autom { w.writeRef(a.Asym, false) w.writeRef(a.Gotype, false) @@ -330,14 +225,14 @@ func (w *objWriter) writeSymDebug(s *LSym) { fmt.Fprintf(ctxt.Bso, "nosplit ") } fmt.Fprintf(ctxt.Bso, "size=%d", s.Size) - if s.Type == STEXT { + if s.Type == objabi.STEXT { fmt.Fprintf(ctxt.Bso, " args=%#x locals=%#x", uint64(s.Func.Args), uint64(s.Func.Locals)) if s.Leaf() { fmt.Fprintf(ctxt.Bso, " leaf") } } fmt.Fprintf(ctxt.Bso, "\n") - if s.Type == STEXT { + if s.Type == objabi.STEXT { for p := s.Func.Text; p != nil; p = p.Link { fmt.Fprintf(ctxt.Bso, "\t%#04x %v\n", uint(int(p.Pc)), p) } @@ -369,7 +264,7 @@ func (w *objWriter) writeSymDebug(s *LSym) { name := "" if r.Sym != nil { name = r.Sym.Name - } else if r.Type == R_TLS_LE { + } else if r.Type == objabi.R_TLS_LE { name = "TLS" } if ctxt.Arch.InFamily(sys.ARM, sys.PPC64) { @@ -415,7 +310,7 @@ func (w *objWriter) writeSym(s *LSym) { w.writeRefIndex(r.Sym) } - if s.Type != STEXT { + if s.Type != objabi.STEXT { return } @@ -442,9 +337,9 @@ func (w *objWriter) writeSym(s *LSym) { w.writeRefIndex(a.Asym) w.writeInt(int64(a.Aoffset)) if a.Name == NAME_AUTO { - w.writeInt(A_AUTO) + w.writeInt(objabi.A_AUTO) } else if a.Name == NAME_PARAM { - w.writeInt(A_PARAM) + w.writeInt(objabi.A_PARAM) } else { log.Fatalf("%s: invalid local variable type %d", s.Name, a.Name) } @@ -552,12 +447,12 @@ func (c dwCtxt) AddSectionOffset(s dwarf.Sym, size int, t interface{}, ofs int64 rsym := t.(*LSym) ls.WriteAddr(c.Link, ls.Size, size, rsym, ofs) r := &ls.R[len(ls.R)-1] - r.Type = R_DWARFREF + r.Type = objabi.R_DWARFREF } // dwarfSym returns the DWARF symbol for TEXT symbol. func (ctxt *Link) dwarfSym(s *LSym) *LSym { - if s.Type != STEXT { + if s.Type != objabi.STEXT { ctxt.Diag("dwarfSym of non-TEXT %v", s) } if s.Func.dwarfSym == nil { |