// The shared library contains a note containing the ABI hash that is mapped into
// memory and there is a local symbol called go.link.abihashbytes that points 16
// bytes into it.
func testABIHashNote(t *testing.T, f *elf.File, note *note) {
if note.section.Flags != elf.SHF_ALLOC {
t.Errorf("abi hash section has flags %v", note.section.Flags)
}
if !isOffsetLoaded(f, note.section.Offset) {
t.Errorf("abihash section not contained in PT_LOAD segment")
}
var hashbytes elf.Symbol
symbols, err := f.Symbols()
if err != nil {
t.Errorf("error reading symbols %v", err)
return
}
for _, sym := range symbols {
if sym.Name == "go.link.abihashbytes" {
hashbytes = sym
}
}
if hashbytes.Name == "" {
t.Errorf("no symbol called go.link.abihashbytes")
return
}
if elf.ST_BIND(hashbytes.Info) != elf.STB_LOCAL {
t.Errorf("%s has incorrect binding %v", hashbytes.Name, elf.ST_BIND(hashbytes.Info))
}
if f.Sections[hashbytes.Section] != note.section {
t.Errorf("%s has incorrect section %v", hashbytes.Name, f.Sections[hashbytes.Section].Name)
}
if hashbytes.Value-note.section.Addr != 16 {
t.Errorf("%s has incorrect offset into section %d", hashbytes.Name, hashbytes.Value-note.section.Addr)
}
}
func elfSymbols(f *os.File) (syms []Sym, goarch string) {
p, err := elf.NewFile(f)
if err != nil {
errorf("parsing %s: %v", f.Name(), err)
return
}
elfSyms, err := p.Symbols()
if err != nil {
errorf("parsing %s: %v", f.Name(), err)
return
}
switch p.Machine {
case elf.EM_X86_64:
goarch = "amd64"
case elf.EM_386:
goarch = "386"
case elf.EM_ARM:
goarch = "arm"
}
for _, s := range elfSyms {
sym := Sym{Addr: s.Value, Name: s.Name, Size: int64(s.Size), Code: '?'}
switch s.Section {
case elf.SHN_UNDEF:
sym.Code = 'U'
case elf.SHN_COMMON:
sym.Code = 'B'
default:
i := int(s.Section)
if i < 0 || i >= len(p.Sections) {
break
}
sect := p.Sections[i]
switch sect.Flags & (elf.SHF_WRITE | elf.SHF_ALLOC | elf.SHF_EXECINSTR) {
case elf.SHF_ALLOC | elf.SHF_EXECINSTR:
sym.Code = 'T'
case elf.SHF_ALLOC:
sym.Code = 'R'
case elf.SHF_ALLOC | elf.SHF_WRITE:
sym.Code = 'D'
}
}
if elf.ST_BIND(s.Info) == elf.STB_LOCAL {
sym.Code += 'a' - 'A'
}
syms = append(syms, sym)
}
return
}
func elfSymbols(f *os.File) []Sym {
p, err := elf.NewFile(f)
if err != nil {
errorf("parsing %s: %v", f.Name(), err)
return nil
}
elfSyms, err := p.Symbols()
if err != nil {
errorf("parsing %s: %v", f.Name(), err)
return nil
}
var syms []Sym
for _, s := range elfSyms {
sym := Sym{Addr: s.Value, Name: s.Name, Size: int64(s.Size), Code: '?'}
switch s.Section {
case elf.SHN_UNDEF:
sym.Code = 'U'
case elf.SHN_COMMON:
sym.Code = 'B'
default:
i := int(s.Section)
if i <= 0 || i > len(p.Sections) {
break
}
sect := p.Sections[i-1]
switch sect.Flags & (elf.SHF_WRITE | elf.SHF_ALLOC | elf.SHF_EXECINSTR) {
case elf.SHF_ALLOC | elf.SHF_EXECINSTR:
sym.Code = 'T'
case elf.SHF_ALLOC:
sym.Code = 'R'
case elf.SHF_ALLOC | elf.SHF_WRITE:
sym.Code = 'D'
}
}
if elf.ST_BIND(s.Info) == elf.STB_LOCAL {
sym.Code += 'a' - 'A'
}
syms = append(syms, sym)
}
return syms
}
func (f *elfFile) symbols() ([]Sym, error) {
elfSyms, err := f.elf.Symbols()
if err != nil {
return nil, err
}
var syms []Sym
for _, s := range elfSyms {
sym := Sym{Addr: s.Value, Name: s.Name, Size: int64(s.Size), Code: '?'}
switch s.Section {
case elf.SHN_UNDEF:
sym.Code = 'U'
case elf.SHN_COMMON:
sym.Code = 'B'
default:
i := int(s.Section)
if i < 0 || i >= len(f.elf.Sections) {
break
}
sect := f.elf.Sections[i]
switch sect.Flags & (elf.SHF_WRITE | elf.SHF_ALLOC | elf.SHF_EXECINSTR) {
case elf.SHF_ALLOC | elf.SHF_EXECINSTR:
sym.Code = 'T'
case elf.SHF_ALLOC:
sym.Code = 'R'
case elf.SHF_ALLOC | elf.SHF_WRITE:
sym.Code = 'D'
}
}
if elf.ST_BIND(s.Info) == elf.STB_LOCAL {
sym.Code += 'a' - 'A'
}
syms = append(syms, sym)
}
return syms, nil
}
func ldshlibsyms(shlib string) {
found := false
libpath := ""
for _, libdir := range Ctxt.Libdir {
libpath = filepath.Join(libdir, shlib)
if _, err := os.Stat(libpath); err == nil {
found = true
break
}
}
if !found {
Diag("cannot find shared library: %s", shlib)
return
}
for _, processedlib := range Ctxt.Shlibs {
if processedlib.Path == libpath {
return
}
}
if Ctxt.Debugvlog > 1 && Ctxt.Bso != nil {
fmt.Fprintf(Ctxt.Bso, "%5.2f ldshlibsyms: found library with name %s at %s\n", obj.Cputime(), shlib, libpath)
Ctxt.Bso.Flush()
}
f, err := elf.Open(libpath)
if err != nil {
Diag("cannot open shared library: %s", libpath)
return
}
defer f.Close()
syms, err := f.Symbols()
if err != nil {
Diag("cannot read symbols from shared library: %s", libpath)
return
}
// If a package has a global variable of a type defined in another shared
// library, we need to know the gcmask used by the type, if any. To support
// this, we read all the runtime.gcbits.* symbols, keep a map of address to
// gcmask, and after we're read all the symbols, read the addresses of the
// gcmasks symbols out of the type data to look up the gcmask for each type.
// This depends on the fact that the runtime.gcbits.* symbols are local (so
// the address is actually present in the type data and we don't have to
// search all relocations to find the ones which correspond to gcmasks) and
// also that the shared library we are linking against has not had the symbol
// table removed.
gcmasks := make(map[uint64][]byte)
types := []*LSym{}
var hash []byte
for _, s := range syms {
if elf.ST_TYPE(s.Info) == elf.STT_NOTYPE || elf.ST_TYPE(s.Info) == elf.STT_SECTION {
continue
}
if s.Section == elf.SHN_UNDEF {
continue
}
if strings.HasPrefix(s.Name, "_") {
continue
}
if strings.HasPrefix(s.Name, "runtime.gcbits.") {
gcmasks[s.Value] = readelfsymboldata(f, &s)
}
if s.Name == "go.link.abihashbytes" {
hash = readelfsymboldata(f, &s)
}
if elf.ST_BIND(s.Info) != elf.STB_GLOBAL {
continue
}
lsym := Linklookup(Ctxt, s.Name, 0)
if lsym.Type != 0 && lsym.Dupok == 0 {
Diag(
"Found duplicate symbol %s reading from %s, first found in %s",
s.Name, shlib, lsym.File)
}
lsym.Type = obj.SDYNIMPORT
lsym.ElfType = elf.ST_TYPE(s.Info)
lsym.File = libpath
if strings.HasPrefix(lsym.Name, "type.") {
if f.Sections[s.Section].Type == elf.SHT_PROGBITS {
lsym.P = readelfsymboldata(f, &s)
}
if !strings.HasPrefix(lsym.Name, "type..") {
types = append(types, lsym)
}
}
}
for _, t := range types {
if decodetype_noptr(t) != 0 || decodetype_usegcprog(t) != 0 {
continue
}
addr := decodetype_gcprog_shlib(t)
tgcmask, ok := gcmasks[addr]
if !ok {
Diag("bits not found for %s at %d", t.Name, addr)
}
t.gcmask = tgcmask
}
// We might have overwritten some functions above (this tends to happen for the
// autogenerated type equality/hashing functions) and we don't want to generated
// pcln table entries for these any more so unstitch them from the Textp linked
// list.
var last *LSym
for s := Ctxt.Textp; s != nil; s = s.Next {
if s.Type == obj.SDYNIMPORT {
continue
}
if last == nil {
Ctxt.Textp = s
} else {
last.Next = s
}
last = s
}
if last == nil {
Ctxt.Textp = nil
Ctxt.Etextp = nil
} else {
last.Next = nil
Ctxt.Etextp = last
}
Ctxt.Shlibs = append(Ctxt.Shlibs, Shlib{Path: libpath, Hash: hash})
}