)
const (
- // TODO: the Microsoft doco says IMAGE_SYM_DTYPE_ARRAY is 3 (same with IMAGE_SYM_DTYPE_POINTER and IMAGE_SYM_DTYPE_FUNCTION)
IMAGE_SYM_UNDEFINED = 0
IMAGE_SYM_ABSOLUTE = -1
IMAGE_SYM_DEBUG = -2
IMAGE_SYM_TYPE_DWORD = 15
IMAGE_SYM_TYPE_PCODE = 32768
IMAGE_SYM_DTYPE_NULL = 0
- IMAGE_SYM_DTYPE_POINTER = 0x10
- IMAGE_SYM_DTYPE_FUNCTION = 0x20
- IMAGE_SYM_DTYPE_ARRAY = 0x30
+ IMAGE_SYM_DTYPE_POINTER = 1
+ IMAGE_SYM_DTYPE_FUNCTION = 2
+ IMAGE_SYM_DTYPE_ARRAY = 3
IMAGE_SYM_CLASS_END_OF_FUNCTION = -1
IMAGE_SYM_CLASS_NULL = 0
IMAGE_SYM_CLASS_AUTOMATIC = 1
IMAGE_REL_ARM64_REL32 = 0x0011
)
+const (
+ // When stored into the PLT value for a symbol, this token tells
+ // windynrelocsym to redirect direct references to this symbol to a stub
+ // that loads from the corresponding import symbol and then does
+ // a jump to the loaded value.
+ CreateImportStubPltToken = -2
+
+ // When stored into the GOT value for an import symbol __imp_X this
+ // token tells windynrelocsym to redirect references to the
+ // underlying DYNIMPORT symbol X.
+ RedirectToDynImportGotToken = -2
+)
+
// TODO(brainman): maybe just add ReadAt method to bio.Reader instead of creating peBiobuf
// peBiobuf makes bio.Reader look like io.ReaderAt.
return bld
}
+// peImportSymsState tracks the set of DLL import symbols we've seen
+// while reading host objects. We create a singleton instance of this
+// type, which will persist across multiple host objects.
+type peImportSymsState struct {
+
+ // Text and non-text sections read in by the host object loader.
+ secSyms []loader.Sym
+
+ // SDYNIMPORT symbols encountered along the way
+ dynimports map[loader.Sym]struct{}
+
+ // Loader and arch, for use in postprocessing.
+ l *loader.Loader
+ arch *sys.Arch
+}
+
+var importSymsState *peImportSymsState
+
+func createImportSymsState(l *loader.Loader, arch *sys.Arch) {
+ if importSymsState != nil {
+ return
+ }
+ importSymsState = &peImportSymsState{
+ dynimports: make(map[loader.Sym]struct{}),
+ l: l,
+ arch: arch,
+ }
+}
+
// peLoaderState holds various bits of useful state information needed
-// while loading a PE object file.
+// while loading a single PE object file.
type peLoaderState struct {
l *loader.Loader
arch *sys.Arch
f *pe.File
pn string
sectsyms map[*pe.Section]loader.Sym
- defWithImp map[string]struct{}
comdats map[uint16]int64 // key is section index, val is size
sectdata map[*pe.Section][]byte
localSymVersion int
// comdatDefinitions records the names of symbols for which we've
// previously seen a definition in COMDAT. Key is symbol name, value
// is symbol size (or -1 if we're using the "any" strategy).
-var comdatDefinitions = make(map[string]int64)
+var comdatDefinitions map[string]int64
+
+// Symbols contains the symbols that can be loaded from a PE file.
+type Symbols struct {
+ Textp []loader.Sym // text symbols
+ Resources []loader.Sym // .rsrc section or set of .rsrc$xx sections
+ PData loader.Sym
+ XData loader.Sym
+}
// Load loads the PE file pn from input.
-// Symbols are written into syms, and a slice of the text symbols is returned.
-// If an .rsrc section or set of .rsrc$xx sections is found, its symbols are
-// returned as rsrc.
-func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, input *bio.Reader, pkg string, length int64, pn string) (textp []loader.Sym, rsrc []loader.Sym, err error) {
+// Symbols from the object file are created via the loader 'l'.
+func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, input *bio.Reader, pkg string, length int64, pn string) (*Symbols, error) {
state := &peLoaderState{
l: l,
arch: arch,
localSymVersion: localSymVersion,
pn: pn,
}
+ createImportSymsState(state.l, state.arch)
+ if comdatDefinitions == nil {
+ comdatDefinitions = make(map[string]int64)
+ }
// Some input files are archives containing multiple of
// object files, and pe.NewFile seeks to the start of
// TODO: replace pe.NewFile with pe.Load (grep for "add Load function" in debug/pe for details)
f, err := pe.NewFile(sr)
if err != nil {
- return nil, nil, err
+ return nil, err
}
defer f.Close()
state.f = f
+ var ls Symbols
+
// TODO return error if found .cormeta
// create symbols for mapped sections
switch sect.Characteristics & (pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA | pe.IMAGE_SCN_CNT_INITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ | pe.IMAGE_SCN_MEM_WRITE | pe.IMAGE_SCN_CNT_CODE | pe.IMAGE_SCN_MEM_EXECUTE) {
case pe.IMAGE_SCN_CNT_INITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ: //.rdata
- bld.SetType(sym.SRODATA)
+ if issehsect(arch, sect) {
+ bld.SetType(sym.SSEHSECT)
+ bld.SetAlign(4)
+ } else {
+ bld.SetType(sym.SRODATA)
+ }
case pe.IMAGE_SCN_CNT_UNINITIALIZED_DATA | pe.IMAGE_SCN_MEM_READ | pe.IMAGE_SCN_MEM_WRITE: //.bss
bld.SetType(sym.SNOPTRBSS)
bld.SetType(sym.STEXT)
default:
- return nil, nil, fmt.Errorf("unexpected flags %#06x for PE section %s", sect.Characteristics, sect.Name)
+ return nil, fmt.Errorf("unexpected flags %#06x for PE section %s", sect.Characteristics, sect.Name)
}
if bld.Type() != sym.SNOPTRBSS {
data, err := sect.Data()
if err != nil {
- return nil, nil, err
+ return nil, err
}
state.sectdata[sect] = data
bld.SetData(data)
bld.SetSize(int64(sect.Size))
state.sectsyms[sect] = s
if sect.Name == ".rsrc" || strings.HasPrefix(sect.Name, ".rsrc$") {
- rsrc = append(rsrc, s)
+ ls.Resources = append(ls.Resources, s)
+ } else if bld.Type() == sym.SSEHSECT {
+ if sect.Name == ".pdata" {
+ ls.PData = s
+ } else if sect.Name == ".xdata" {
+ ls.XData = s
+ }
}
}
- // Make a prepass over the symbols to detect situations where
- // we have both a defined symbol X and an import symbol __imp_X
- // (needed by readpesym()).
+ // Make a prepass over the symbols to collect info about COMDAT symbols.
if err := state.preprocessSymbols(); err != nil {
- return nil, nil, err
+ return nil, err
}
// load relocations
}
splitResources := strings.HasPrefix(rsect.Name, ".rsrc$")
+ issehsect := issehsect(arch, rsect)
sb := l.MakeSymbolUpdater(state.sectsyms[rsect])
for j, r := range rsect.Relocs {
if int(r.SymbolTableIndex) >= len(f.COFFSymbols) {
- return nil, nil, fmt.Errorf("relocation number %d symbol index idx=%d cannot be large then number of symbols %d", j, r.SymbolTableIndex, len(f.COFFSymbols))
+ return nil, fmt.Errorf("relocation number %d symbol index idx=%d cannot be large then number of symbols %d", j, r.SymbolTableIndex, len(f.COFFSymbols))
}
pesym := &f.COFFSymbols[r.SymbolTableIndex]
_, gosym, err := state.readpesym(pesym)
if err != nil {
- return nil, nil, err
+ return nil, err
}
if gosym == 0 {
name, err := pesym.FullName(f.StringTable)
if err != nil {
name = string(pesym.Name[:])
}
- return nil, nil, fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
+ return nil, fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
}
rSym := gosym
var rType objabi.RelocType
switch arch.Family {
default:
- return nil, nil, fmt.Errorf("%s: unsupported arch %v", pn, arch.Family)
+ return nil, fmt.Errorf("%s: unsupported arch %v", pn, arch.Family)
case sys.I386, sys.AMD64:
switch r.Type {
default:
- return nil, nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, state.sectsyms[rsect], r.Type)
+ return nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, state.sectsyms[rsect], r.Type)
case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
IMAGE_REL_AMD64_ADDR32NB:
- rType = objabi.R_PCREL
+ if r.Type == IMAGE_REL_AMD64_ADDR32NB {
+ rType = objabi.R_PEIMAGEOFF
+ } else {
+ rType = objabi.R_PCREL
+ }
rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
- rType = objabi.R_ADDR
+ if r.Type == IMAGE_REL_I386_DIR32NB {
+ rType = objabi.R_PEIMAGEOFF
+ } else {
+ rType = objabi.R_ADDR
+ }
// load addend from image
rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
case sys.ARM:
switch r.Type {
default:
- return nil, nil, fmt.Errorf("%s: %v: unknown ARM relocation type %v", pn, state.sectsyms[rsect], r.Type)
+ return nil, fmt.Errorf("%s: %v: unknown ARM relocation type %v", pn, state.sectsyms[rsect], r.Type)
case IMAGE_REL_ARM_SECREL:
rType = objabi.R_PCREL
rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
case IMAGE_REL_ARM_ADDR32, IMAGE_REL_ARM_ADDR32NB:
- rType = objabi.R_ADDR
+ if r.Type == IMAGE_REL_ARM_ADDR32NB {
+ rType = objabi.R_PEIMAGEOFF
+ } else {
+ rType = objabi.R_ADDR
+ }
rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
case sys.ARM64:
switch r.Type {
default:
- return nil, nil, fmt.Errorf("%s: %v: unknown ARM64 relocation type %v", pn, state.sectsyms[rsect], r.Type)
+ return nil, fmt.Errorf("%s: %v: unknown ARM64 relocation type %v", pn, state.sectsyms[rsect], r.Type)
case IMAGE_REL_ARM64_ADDR32, IMAGE_REL_ARM64_ADDR32NB:
- rType = objabi.R_ADDR
+ if r.Type == IMAGE_REL_ARM64_ADDR32NB {
+ rType = objabi.R_PEIMAGEOFF
+ } else {
+ rType = objabi.R_ADDR
+ }
rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
}
if issect(pesym) || splitResources {
rAdd += int64(pesym.Value)
}
+ if issehsect {
+ // .pdata and .xdata sections can contain records
+ // associated to functions that won't be used in
+ // the final binary, in which case the relocation
+ // target symbol won't be reachable.
+ rType |= objabi.R_WEAK
+ }
rel, _ := sb.AddRel(rType)
rel.SetOff(rOff)
rel.SetSiz(rSize)
rel.SetSym(rSym)
rel.SetAdd(rAdd)
+
}
sb.SortRelocs()
name, err := pesym.FullName(f.StringTable)
if err != nil {
- return nil, nil, err
+ return nil, err
}
if name == "" {
continue
bld, s, err := state.readpesym(pesym)
if err != nil {
- return nil, nil, err
+ return nil, err
}
if pesym.SectionNumber == 0 { // extern
- if l.SymType(s) == sym.SDYNIMPORT {
- bld = makeUpdater(l, bld, s)
- bld.SetPlt(-2) // flag for dynimport in PE object files.
- }
if l.SymType(s) == sym.SXREF && pesym.Value > 0 { // global data
bld = makeUpdater(l, bld, s)
bld.SetType(sym.SNOPTRDATA)
} else if pesym.SectionNumber > 0 && int(pesym.SectionNumber) <= len(f.Sections) {
sect = f.Sections[pesym.SectionNumber-1]
if _, found := state.sectsyms[sect]; !found {
- return nil, nil, fmt.Errorf("%s: %v: missing sect.sym", pn, s)
+ return nil, fmt.Errorf("%s: %v: missing sect.sym", pn, s)
}
} else {
- return nil, nil, fmt.Errorf("%s: %v: sectnum < 0!", pn, s)
+ return nil, fmt.Errorf("%s: %v: sectnum < 0!", pn, s)
}
if sect == nil {
- return nil, nil, nil
+ return nil, nil
}
// Check for COMDAT symbol.
}
outerName := l.SymName(l.OuterSym(s))
sectName := l.SymName(state.sectsyms[sect])
- return nil, nil, fmt.Errorf("%s: duplicate symbol reference: %s in both %s and %s", pn, l.SymName(s), outerName, sectName)
+ return nil, fmt.Errorf("%s: duplicate symbol reference: %s in both %s and %s", pn, l.SymName(s), outerName, sectName)
}
bld = makeUpdater(l, bld, s)
bld.SetSize(4)
if l.SymType(sectsym) == sym.STEXT {
if bld.External() && !bld.DuplicateOK() {
- return nil, nil, fmt.Errorf("%s: duplicate symbol definition", l.SymName(s))
+ return nil, fmt.Errorf("%s: duplicate symbol definition", l.SymName(s))
}
bld.SetExternal(true)
}
// This is a COMDAT definition. Record that we're picking
// this instance so that we can ignore future defs.
if _, ok := comdatDefinitions[l.SymName(s)]; ok {
- return nil, nil, fmt.Errorf("internal error: preexisting COMDAT definition for %q", name)
+ return nil, fmt.Errorf("internal error: preexisting COMDAT definition for %q", name)
}
comdatDefinitions[l.SymName(s)] = sz
}
continue
}
l.SortSub(s)
+ importSymsState.secSyms = append(importSymsState.secSyms, s)
if l.SymType(s) == sym.STEXT {
for ; s != 0; s = l.SubSym(s) {
if l.AttrOnList(s) {
- return nil, nil, fmt.Errorf("symbol %s listed multiple times", l.SymName(s))
+ return nil, fmt.Errorf("symbol %s listed multiple times", l.SymName(s))
}
l.SetAttrOnList(s, true)
- textp = append(textp, s)
+ ls.Textp = append(ls.Textp, s)
}
}
}
- return textp, rsrc, nil
+ if ls.PData != 0 {
+ processSEH(l, arch, ls.PData, ls.XData)
+ }
+
+ return &ls, nil
+}
+
+// PostProcessImports works to resolve inconsistencies with DLL import
+// symbols; it is needed when building with more "modern" C compilers
+// with internal linkage.
+//
+// Background: DLL import symbols are data (SNOPTRDATA) symbols whose
+// name is of the form "__imp_XXX", which contain a pointer/reference
+// to symbol XXX. It's possible to have import symbols for both data
+// symbols ("__imp__fmode") and text symbols ("__imp_CreateEventA").
+// In some case import symbols are just references to some external
+// thing, and in other cases we see actual definitions of import
+// symbols when reading host objects.
+//
+// Previous versions of the linker would in most cases immediately
+// "forward" import symbol references, e.g. treat a references to
+// "__imp_XXX" a references to "XXX", however this doesn't work well
+// with more modern compilers, where you can sometimes see import
+// symbols that are defs (as opposed to external refs).
+//
+// The main actions taken below are to search for references to
+// SDYNIMPORT symbols in host object text/data sections and flag the
+// symbols for later fixup. When we see a reference to an import
+// symbol __imp_XYZ where XYZ corresponds to some SDYNIMPORT symbol,
+// we flag the symbol (via GOT setting) so that it can be redirected
+// to XYZ later in windynrelocsym. When we see a direct reference to
+// an SDYNIMPORT symbol XYZ, we also flag the symbol (via PLT setting)
+// to indicated that the reference will need to be redirected to a
+// stub.
+func PostProcessImports() error {
+ ldr := importSymsState.l
+ arch := importSymsState.arch
+ keeprelocneeded := make(map[loader.Sym]loader.Sym)
+ for _, s := range importSymsState.secSyms {
+ isText := ldr.SymType(s) == sym.STEXT
+ relocs := ldr.Relocs(s)
+ for i := 0; i < relocs.Count(); i++ {
+ r := relocs.At(i)
+ rs := r.Sym()
+ if ldr.SymType(rs) == sym.SDYNIMPORT {
+ // Tag the symbol for later stub generation.
+ ldr.SetPlt(rs, CreateImportStubPltToken)
+ continue
+ }
+ isym, err := LookupBaseFromImport(rs, ldr, arch)
+ if err != nil {
+ return err
+ }
+ if isym == 0 {
+ continue
+ }
+ if ldr.SymType(isym) != sym.SDYNIMPORT {
+ continue
+ }
+ // For non-text symbols, forward the reference from __imp_X to
+ // X immediately.
+ if !isText {
+ r.SetSym(isym)
+ continue
+ }
+ // Flag this imp symbol to be processed later in windynrelocsym.
+ ldr.SetGot(rs, RedirectToDynImportGotToken)
+ // Consistency check: should be no PLT token here.
+ splt := ldr.SymPlt(rs)
+ if splt != -1 {
+ return fmt.Errorf("internal error: import symbol %q has invalid PLT setting %d", ldr.SymName(rs), splt)
+ }
+ // Flag for dummy relocation.
+ keeprelocneeded[rs] = isym
+ }
+ }
+ for k, v := range keeprelocneeded {
+ sb := ldr.MakeSymbolUpdater(k)
+ r, _ := sb.AddRel(objabi.R_KEEP)
+ r.SetSym(v)
+ }
+ importSymsState = nil
+ return nil
+}
+
+func issehsect(arch *sys.Arch, s *pe.Section) bool {
+ return arch.Family == sys.AMD64 && (s.Name == ".pdata" || s.Name == ".xdata")
}
func issect(s *pe.COFFSymbol) bool {
name = state.l.SymName(state.sectsyms[state.f.Sections[pesym.SectionNumber-1]])
} else {
name = symname
- if strings.HasPrefix(symname, "__imp_") {
- orig := symname[len("__imp_"):]
- if _, ok := state.defWithImp[orig]; ok {
- // Don't rename __imp_XXX to XXX, since if we do this
- // we'll wind up with a duplicate definition. One
- // example is "__acrt_iob_func"; see commit b295099
- // from git://git.code.sf.net/p/mingw-w64/mingw-w64
- // for details.
- } else {
- name = strings.TrimPrefix(name, "__imp_") // __imp_Name => Name
- }
- }
// A note on the "_main" exclusion below: the main routine
// defined by the Go runtime is named "_main", not "main", so
// when reading references to _main from a host object we want
// to avoid rewriting "_main" to "main" in this specific
// instance. See #issuecomment-1143698749 on #35006 for more
// details on this problem.
- if state.arch.Family == sys.I386 && name[0] == '_' && name != "_main" {
+ if state.arch.Family == sys.I386 && name[0] == '_' && name != "_main" && !strings.HasPrefix(name, "__imp_") {
name = name[1:] // _Name => Name
}
}
var s loader.Sym
var bld *loader.SymbolBuilder
- switch pesym.Type {
+ // Microsoft's PE documentation is contradictory. It says that the symbol's complex type
+ // is stored in the pesym.Type most significant byte, but MSVC, LLVM, and mingw store it
+ // in the 4 high bits of the less significant byte.
+ switch uint8(pesym.Type&0xf0) >> 4 {
default:
return nil, 0, fmt.Errorf("%s: invalid symbol type %d", symname, pesym.Type)
bld = makeUpdater(state.l, bld, s)
bld.SetType(sym.SXREF)
}
- if strings.HasPrefix(symname, "__imp_") {
- bld = makeUpdater(state.l, bld, s)
- bld.SetGot(-2) // flag for __imp_
- }
return bld, s, nil
}
}
// Examine symbol defs.
- imp := make(map[string]struct{})
- def := make(map[string]struct{})
for i, numaux := 0, 0; i < len(state.f.COFFSymbols); i += numaux + 1 {
pesym := &state.f.COFFSymbols[i]
numaux = int(pesym.NumberOfAuxSymbols)
if err != nil {
return err
}
- def[symname] = struct{}{}
- if strings.HasPrefix(symname, "__imp_") {
- imp[strings.TrimPrefix(symname, "__imp_")] = struct{}{}
- }
if _, isc := state.comdats[uint16(pesym.SectionNumber-1)]; !isc {
continue
}
return fmt.Errorf("internal error: unsupported COMDAT selection strategy found in path=%s sec=%d strategy=%d idx=%d, please file a bug", state.pn, auxsymp.SecNum, auxsymp.Selection, i)
}
}
- state.defWithImp = make(map[string]struct{})
- for n := range imp {
- if _, ok := def[n]; ok {
- state.defWithImp[n] = struct{}{}
- }
- }
return nil
}
+
+// LookupBaseFromImport examines the symbol "s" to see if it
+// corresponds to an import symbol (name of the form "__imp_XYZ") and
+// if so, it looks up the underlying target of the import symbol and
+// returns it. An error is returned if the symbol is of the form
+// "__imp_XYZ" but no XYZ can be found.
+func LookupBaseFromImport(s loader.Sym, ldr *loader.Loader, arch *sys.Arch) (loader.Sym, error) {
+ sname := ldr.SymName(s)
+ if !strings.HasPrefix(sname, "__imp_") {
+ return 0, nil
+ }
+ basename := sname[len("__imp_"):]
+ if arch.Family == sys.I386 && basename[0] == '_' {
+ basename = basename[1:] // _Name => Name
+ }
+ isym := ldr.Lookup(basename, 0)
+ if isym == 0 {
+ return 0, fmt.Errorf("internal error: import symbol %q with no underlying sym", sname)
+ }
+ return isym, nil
+}