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go/src/cmd/link/internal/ld/symtab.go
Ian Lance Taylor 5331e7e9df cmd/internal/obj, cmd/link: fix st_other field on PPC64 
In PPC64 ELF files, the st_other field indicates the number of
prologue instructions between the global and local entry points.
We add the instructions in the compiler and assembler if -shared is used.
We were assuming that the instructions were present when building a
c-archive or PIE or doing dynamic linking, on the assumption that those
are the cases where the go tool would be building with -shared.
That assumption fails when using some other tool, such as Bazel,
that does not necessarily use -shared in exactly the same way.

This CL records in the object file whether a symbol was compiled
with -shared (this will be the same for all symbols in a given compilation)
and uses that information when setting the st_other field.

Fixes #20290.

Change-Id: Ib2b77e16aef38824871102e3c244fcf04a86c6ea
Reviewed-on: https://go-review.googlesource.com/43051
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-05-09 23:36:51 +00:00

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// Inferno utils/6l/span.c
// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/span.c
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package ld
import (
"cmd/internal/objabi"
"cmd/internal/sys"
"fmt"
"path/filepath"
"strings"
)
// Symbol table.
func putelfstr(s string) int {
if len(Elfstrdat) == 0 && s != "" {
// first entry must be empty string
putelfstr("")
}
off := len(Elfstrdat)
Elfstrdat = append(Elfstrdat, s...)
Elfstrdat = append(Elfstrdat, 0)
return off
}
func putelfsyment(off int, addr int64, size int64, info int, shndx int, other int) {
if elf64 {
Thearch.Lput(uint32(off))
Cput(uint8(info))
Cput(uint8(other))
Thearch.Wput(uint16(shndx))
Thearch.Vput(uint64(addr))
Thearch.Vput(uint64(size))
Symsize += ELF64SYMSIZE
} else {
Thearch.Lput(uint32(off))
Thearch.Lput(uint32(addr))
Thearch.Lput(uint32(size))
Cput(uint8(info))
Cput(uint8(other))
Thearch.Wput(uint16(shndx))
Symsize += ELF32SYMSIZE
}
}
var numelfsym int = 1 // 0 is reserved
var elfbind int
func putelfsym(ctxt *Link, x *Symbol, s string, t SymbolType, addr int64, go_ *Symbol) {
var typ int
switch t {
default:
return
case TextSym:
typ = STT_FUNC
case DataSym, BSSSym:
typ = STT_OBJECT
case UndefinedSym:
// ElfType is only set for symbols read from Go shared libraries, but
// for other symbols it is left as STT_NOTYPE which is fine.
typ = int(x.ElfType)
case TLSSym:
typ = STT_TLS
}
size := x.Size
if t == UndefinedSym {
size = 0
}
xo := x
for xo.Outer != nil {
xo = xo.Outer
}
var elfshnum int
if xo.Type == SDYNIMPORT || xo.Type == SHOSTOBJ {
elfshnum = SHN_UNDEF
} else {
if xo.Sect == nil {
Errorf(x, "missing section in putelfsym")
return
}
if xo.Sect.Elfsect == nil {
Errorf(x, "missing ELF section in putelfsym")
return
}
elfshnum = xo.Sect.Elfsect.shnum
}
// One pass for each binding: STB_LOCAL, STB_GLOBAL,
// maybe one day STB_WEAK.
bind := STB_GLOBAL
if x.Version != 0 || (x.Type&SHIDDEN != 0) || x.Attr.Local() {
bind = STB_LOCAL
}
// In external linking mode, we have to invoke gcc with -rdynamic
// to get the exported symbols put into the dynamic symbol table.
// To avoid filling the dynamic table with lots of unnecessary symbols,
// mark all Go symbols local (not global) in the final executable.
// But when we're dynamically linking, we need all those global symbols.
if !ctxt.DynlinkingGo() && Linkmode == LinkExternal && !x.Attr.CgoExportStatic() && elfshnum != SHN_UNDEF {
bind = STB_LOCAL
}
if Linkmode == LinkExternal && elfshnum != SHN_UNDEF {
addr -= int64(xo.Sect.Vaddr)
}
other := STV_DEFAULT
if x.Type&SHIDDEN != 0 {
other = STV_HIDDEN
}
if SysArch.Family == sys.PPC64 && typ == STT_FUNC && x.Attr.Shared() && x.Name != "runtime.duffzero" && x.Name != "runtime.duffcopy" {
// On ppc64 the top three bits of the st_other field indicate how
// many instructions separate the global and local entry points. In
// our case it is two instructions, indicated by the value 3.
// The conditions here match those in preprocess in
// cmd/internal/obj/ppc64/obj9.go, which is where the
// instructions are inserted.
other |= 3 << 5
}
// When dynamically linking, we create Symbols by reading the names from
// the symbol tables of the shared libraries and so the names need to
// match exactly. Tools like DTrace will have to wait for now.
if !ctxt.DynlinkingGo() {
// Rewrite · to . for ASCII-only tools like DTrace (sigh)
s = strings.Replace(s, "·", ".", -1)
}
if ctxt.DynlinkingGo() && bind == STB_GLOBAL && elfbind == STB_LOCAL && x.Type == STEXT {
// When dynamically linking, we want references to functions defined
// in this module to always be to the function object, not to the
// PLT. We force this by writing an additional local symbol for every
// global function symbol and making all relocations against the
// global symbol refer to this local symbol instead (see
// (*Symbol).ElfsymForReloc). This is approximately equivalent to the
// ELF linker -Bsymbolic-functions option, but that is buggy on
// several platforms.
putelfsyment(putelfstr("local."+s), addr, size, STB_LOCAL<<4|typ&0xf, elfshnum, other)
x.LocalElfsym = int32(numelfsym)
numelfsym++
return
} else if bind != elfbind {
return
}
putelfsyment(putelfstr(s), addr, size, bind<<4|typ&0xf, elfshnum, other)
x.Elfsym = int32(numelfsym)
numelfsym++
}
func putelfsectionsym(s *Symbol, shndx int) {
putelfsyment(0, 0, 0, STB_LOCAL<<4|STT_SECTION, shndx, 0)
s.Elfsym = int32(numelfsym)
numelfsym++
}
func Asmelfsym(ctxt *Link) {
// the first symbol entry is reserved
putelfsyment(0, 0, 0, STB_LOCAL<<4|STT_NOTYPE, 0, 0)
dwarfaddelfsectionsyms(ctxt)
// Some linkers will add a FILE sym if one is not present.
// Avoid having the working directory inserted into the symbol table.
// It is added with a name to avoid problems with external linking
// encountered on some versions of Solaris. See issue #14957.
putelfsyment(putelfstr("go.go"), 0, 0, STB_LOCAL<<4|STT_FILE, SHN_ABS, 0)
numelfsym++
elfbind = STB_LOCAL
genasmsym(ctxt, putelfsym)
elfbind = STB_GLOBAL
elfglobalsymndx = numelfsym
genasmsym(ctxt, putelfsym)
}
func putplan9sym(ctxt *Link, x *Symbol, s string, typ SymbolType, addr int64, go_ *Symbol) {
t := int(typ)
switch typ {
case TextSym, DataSym, BSSSym:
if x.Version != 0 {
t += 'a' - 'A'
}
fallthrough
case AutoSym, ParamSym, FileSym, FrameSym:
l := 4
if Headtype == objabi.Hplan9 && SysArch.Family == sys.AMD64 && !Flag8 {
Lputb(uint32(addr >> 32))
l = 8
}
Lputb(uint32(addr))
Cput(uint8(t + 0x80)) /* 0x80 is variable length */
var i int
/* skip the '<' in filenames */
if t == FileSym {
s = s[1:]
}
for i = 0; i < len(s); i++ {
Cput(s[i])
}
Cput(0)
Symsize += int32(l) + 1 + int32(i) + 1
default:
return
}
}
func Asmplan9sym(ctxt *Link) {
genasmsym(ctxt, putplan9sym)
}
var symt *Symbol
var encbuf [10]byte
func Wputb(w uint16) { Cwrite(Append16b(encbuf[:0], w)) }
func Lputb(l uint32) { Cwrite(Append32b(encbuf[:0], l)) }
func Vputb(v uint64) { Cwrite(Append64b(encbuf[:0], v)) }
func Wputl(w uint16) { Cwrite(Append16l(encbuf[:0], w)) }
func Lputl(l uint32) { Cwrite(Append32l(encbuf[:0], l)) }
func Vputl(v uint64) { Cwrite(Append64l(encbuf[:0], v)) }
func Append16b(b []byte, v uint16) []byte {
return append(b, uint8(v>>8), uint8(v))
}
func Append16l(b []byte, v uint16) []byte {
return append(b, uint8(v), uint8(v>>8))
}
func Append32b(b []byte, v uint32) []byte {
return append(b, uint8(v>>24), uint8(v>>16), uint8(v>>8), uint8(v))
}
func Append32l(b []byte, v uint32) []byte {
return append(b, uint8(v), uint8(v>>8), uint8(v>>16), uint8(v>>24))
}
func Append64b(b []byte, v uint64) []byte {
return append(b, uint8(v>>56), uint8(v>>48), uint8(v>>40), uint8(v>>32),
uint8(v>>24), uint8(v>>16), uint8(v>>8), uint8(v))
}
func Append64l(b []byte, v uint64) []byte {
return append(b, uint8(v), uint8(v>>8), uint8(v>>16), uint8(v>>24),
uint8(v>>32), uint8(v>>40), uint8(v>>48), uint8(v>>56))
}
type byPkg []*Library
func (libs byPkg) Len() int {
return len(libs)
}
func (libs byPkg) Less(a, b int) bool {
return libs[a].Pkg < libs[b].Pkg
}
func (libs byPkg) Swap(a, b int) {
libs[a], libs[b] = libs[b], libs[a]
}
// Create a table with information on the text sections.
func textsectionmap(ctxt *Link) uint32 {
t := ctxt.Syms.Lookup("runtime.textsectionmap", 0)
t.Type = SRODATA
t.Attr |= AttrReachable
nsections := int64(0)
for _, sect := range Segtext.Sections {
if sect.Name == ".text" {
nsections++
} else {
break
}
}
Symgrow(t, 3*nsections*int64(SysArch.PtrSize))
off := int64(0)
n := 0
// The vaddr for each text section is the difference between the section's
// Vaddr and the Vaddr for the first text section as determined at compile
// time.
// The symbol for the first text section is named runtime.text as before.
// Additional text sections are named runtime.text.n where n is the
// order of creation starting with 1. These symbols provide the section's
// address after relocation by the linker.
textbase := Segtext.Sections[0].Vaddr
for _, sect := range Segtext.Sections {
if sect.Name != ".text" {
break
}
off = setuint(ctxt, t, off, sect.Vaddr-textbase)
off = setuint(ctxt, t, off, sect.Length)
if n == 0 {
s := ctxt.Syms.ROLookup("runtime.text", 0)
if s == nil {
Errorf(nil, "Unable to find symbol runtime.text\n")
}
off = setaddr(ctxt, t, off, s)
} else {
s := ctxt.Syms.Lookup(fmt.Sprintf("runtime.text.%d", n), 0)
if s == nil {
Errorf(nil, "Unable to find symbol runtime.text.%d\n", n)
}
off = setaddr(ctxt, t, off, s)
}
n++
}
return uint32(n)
}
func (ctxt *Link) symtab() {
dosymtype(ctxt)
// Define these so that they'll get put into the symbol table.
// data.c:/^address will provide the actual values.
ctxt.xdefine("runtime.text", STEXT, 0)
ctxt.xdefine("runtime.etext", STEXT, 0)
ctxt.xdefine("runtime.itablink", SRODATA, 0)
ctxt.xdefine("runtime.eitablink", SRODATA, 0)
ctxt.xdefine("runtime.rodata", SRODATA, 0)
ctxt.xdefine("runtime.erodata", SRODATA, 0)
ctxt.xdefine("runtime.types", SRODATA, 0)
ctxt.xdefine("runtime.etypes", SRODATA, 0)
ctxt.xdefine("runtime.noptrdata", SNOPTRDATA, 0)
ctxt.xdefine("runtime.enoptrdata", SNOPTRDATA, 0)
ctxt.xdefine("runtime.data", SDATA, 0)
ctxt.xdefine("runtime.edata", SDATA, 0)
ctxt.xdefine("runtime.bss", SBSS, 0)
ctxt.xdefine("runtime.ebss", SBSS, 0)
ctxt.xdefine("runtime.noptrbss", SNOPTRBSS, 0)
ctxt.xdefine("runtime.enoptrbss", SNOPTRBSS, 0)
ctxt.xdefine("runtime.end", SBSS, 0)
ctxt.xdefine("runtime.epclntab", SRODATA, 0)
ctxt.xdefine("runtime.esymtab", SRODATA, 0)
// garbage collection symbols
s := ctxt.Syms.Lookup("runtime.gcdata", 0)
s.Type = SRODATA
s.Size = 0
s.Attr |= AttrReachable
ctxt.xdefine("runtime.egcdata", SRODATA, 0)
s = ctxt.Syms.Lookup("runtime.gcbss", 0)
s.Type = SRODATA
s.Size = 0
s.Attr |= AttrReachable
ctxt.xdefine("runtime.egcbss", SRODATA, 0)
// pseudo-symbols to mark locations of type, string, and go string data.
var symtype *Symbol
var symtyperel *Symbol
if UseRelro() && (Buildmode == BuildmodeCArchive || Buildmode == BuildmodeCShared || Buildmode == BuildmodePIE) {
s = ctxt.Syms.Lookup("type.*", 0)
s.Type = STYPE
s.Size = 0
s.Attr |= AttrReachable
symtype = s
s = ctxt.Syms.Lookup("typerel.*", 0)
s.Type = STYPERELRO
s.Size = 0
s.Attr |= AttrReachable
symtyperel = s
} else if !ctxt.DynlinkingGo() {
s = ctxt.Syms.Lookup("type.*", 0)
s.Type = STYPE
s.Size = 0
s.Attr |= AttrReachable
symtype = s
symtyperel = s
}
groupSym := func(name string, t SymKind) *Symbol {
s := ctxt.Syms.Lookup(name, 0)
s.Type = t
s.Size = 0
s.Attr |= AttrLocal | AttrReachable
return s
}
var (
symgostring = groupSym("go.string.*", SGOSTRING)
symgofunc = groupSym("go.func.*", SGOFUNC)
symgcbits = groupSym("runtime.gcbits.*", SGCBITS)
)
var symgofuncrel *Symbol
if !ctxt.DynlinkingGo() {
if UseRelro() {
symgofuncrel = groupSym("go.funcrel.*", SGOFUNCRELRO)
} else {
symgofuncrel = symgofunc
}
}
symitablink := ctxt.Syms.Lookup("runtime.itablink", 0)
symitablink.Type = SITABLINK
symt = ctxt.Syms.Lookup("runtime.symtab", 0)
symt.Attr |= AttrLocal
symt.Type = SSYMTAB
symt.Size = 0
symt.Attr |= AttrReachable
nitablinks := 0
// assign specific types so that they sort together.
// within a type they sort by size, so the .* symbols
// just defined above will be first.
// hide the specific symbols.
for _, s := range ctxt.Syms.Allsym {
if !s.Attr.Reachable() || s.Attr.Special() || s.Type != SRODATA {
continue
}
switch {
case strings.HasPrefix(s.Name, "type."):
if !ctxt.DynlinkingGo() {
s.Attr |= AttrNotInSymbolTable
}
if UseRelro() {
s.Type = STYPERELRO
s.Outer = symtyperel
} else {
s.Type = STYPE
s.Outer = symtype
}
case strings.HasPrefix(s.Name, "go.importpath.") && UseRelro():
// Keep go.importpath symbols in the same section as types and
// names, as they can be referred to by a section offset.
s.Type = STYPERELRO
case strings.HasPrefix(s.Name, "go.itablink."):
nitablinks++
s.Type = SITABLINK
s.Attr |= AttrNotInSymbolTable
s.Outer = symitablink
case strings.HasPrefix(s.Name, "go.string."):
s.Type = SGOSTRING
s.Attr |= AttrNotInSymbolTable
s.Outer = symgostring
case strings.HasPrefix(s.Name, "runtime.gcbits."):
s.Type = SGCBITS
s.Attr |= AttrNotInSymbolTable
s.Outer = symgcbits
case strings.HasSuffix(s.Name, "·f"):
if !ctxt.DynlinkingGo() {
s.Attr |= AttrNotInSymbolTable
}
if UseRelro() {
s.Type = SGOFUNCRELRO
s.Outer = symgofuncrel
} else {
s.Type = SGOFUNC
s.Outer = symgofunc
}
case strings.HasPrefix(s.Name, "gcargs."),
strings.HasPrefix(s.Name, "gclocals."),
strings.HasPrefix(s.Name, "gclocals·"),
strings.HasPrefix(s.Name, "inltree."):
s.Type = SGOFUNC
s.Attr |= AttrNotInSymbolTable
s.Outer = symgofunc
s.Align = 4
liveness += (s.Size + int64(s.Align) - 1) &^ (int64(s.Align) - 1)
}
}
if Buildmode == BuildmodeShared {
abihashgostr := ctxt.Syms.Lookup("go.link.abihash."+filepath.Base(*flagOutfile), 0)
abihashgostr.Attr |= AttrReachable
abihashgostr.Type = SRODATA
hashsym := ctxt.Syms.Lookup("go.link.abihashbytes", 0)
Addaddr(ctxt, abihashgostr, hashsym)
adduint(ctxt, abihashgostr, uint64(hashsym.Size))
}
if Buildmode == BuildmodePlugin || ctxt.Syms.ROLookup("plugin.Open", 0) != nil {
for _, l := range ctxt.Library {
s := ctxt.Syms.Lookup("go.link.pkghashbytes."+l.Pkg, 0)
s.Attr |= AttrReachable
s.Type = SRODATA
s.Size = int64(len(l.hash))
s.P = []byte(l.hash)
str := ctxt.Syms.Lookup("go.link.pkghash."+l.Pkg, 0)
str.Attr |= AttrReachable
str.Type = SRODATA
Addaddr(ctxt, str, s)
adduint(ctxt, str, uint64(len(l.hash)))
}
}
nsections := textsectionmap(ctxt)
// Information about the layout of the executable image for the
// runtime to use. Any changes here must be matched by changes to
// the definition of moduledata in runtime/symtab.go.
// This code uses several global variables that are set by pcln.go:pclntab.
moduledata := ctxt.Moduledata
// The pclntab slice
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.pclntab", 0))
adduint(ctxt, moduledata, uint64(ctxt.Syms.Lookup("runtime.pclntab", 0).Size))
adduint(ctxt, moduledata, uint64(ctxt.Syms.Lookup("runtime.pclntab", 0).Size))
// The ftab slice
Addaddrplus(ctxt, moduledata, ctxt.Syms.Lookup("runtime.pclntab", 0), int64(pclntabPclntabOffset))
adduint(ctxt, moduledata, uint64(pclntabNfunc+1))
adduint(ctxt, moduledata, uint64(pclntabNfunc+1))
// The filetab slice
Addaddrplus(ctxt, moduledata, ctxt.Syms.Lookup("runtime.pclntab", 0), int64(pclntabFiletabOffset))
adduint(ctxt, moduledata, uint64(len(ctxt.Filesyms))+1)
adduint(ctxt, moduledata, uint64(len(ctxt.Filesyms))+1)
// findfunctab
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.findfunctab", 0))
// minpc, maxpc
Addaddr(ctxt, moduledata, pclntabFirstFunc)
Addaddrplus(ctxt, moduledata, pclntabLastFunc, pclntabLastFunc.Size)
// pointers to specific parts of the module
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.text", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.etext", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.noptrdata", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.enoptrdata", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.data", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.edata", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.bss", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.ebss", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.noptrbss", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.enoptrbss", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.end", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.gcdata", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.gcbss", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.types", 0))
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.etypes", 0))
// text section information
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.textsectionmap", 0))
adduint(ctxt, moduledata, uint64(nsections))
adduint(ctxt, moduledata, uint64(nsections))
// The typelinks slice
typelinkSym := ctxt.Syms.Lookup("runtime.typelink", 0)
ntypelinks := uint64(typelinkSym.Size) / 4
Addaddr(ctxt, moduledata, typelinkSym)
adduint(ctxt, moduledata, ntypelinks)
adduint(ctxt, moduledata, ntypelinks)
// The itablinks slice
Addaddr(ctxt, moduledata, ctxt.Syms.Lookup("runtime.itablink", 0))
adduint(ctxt, moduledata, uint64(nitablinks))
adduint(ctxt, moduledata, uint64(nitablinks))
// The ptab slice
if ptab := ctxt.Syms.ROLookup("go.plugin.tabs", 0); ptab != nil && ptab.Attr.Reachable() {
ptab.Attr |= AttrLocal
ptab.Type = SRODATA
nentries := uint64(len(ptab.P) / 8) // sizeof(nameOff) + sizeof(typeOff)
Addaddr(ctxt, moduledata, ptab)
adduint(ctxt, moduledata, nentries)
adduint(ctxt, moduledata, nentries)
} else {
adduint(ctxt, moduledata, 0)
adduint(ctxt, moduledata, 0)
adduint(ctxt, moduledata, 0)
}
if Buildmode == BuildmodePlugin {
addgostring(ctxt, moduledata, "go.link.thispluginpath", *flagPluginPath)
pkghashes := ctxt.Syms.Lookup("go.link.pkghashes", 0)
pkghashes.Attr |= AttrReachable
pkghashes.Attr |= AttrLocal
pkghashes.Type = SRODATA
for i, l := range ctxt.Library {
// pkghashes[i].name
addgostring(ctxt, pkghashes, fmt.Sprintf("go.link.pkgname.%d", i), l.Pkg)
// pkghashes[i].linktimehash
addgostring(ctxt, pkghashes, fmt.Sprintf("go.link.pkglinkhash.%d", i), string(l.hash))
// pkghashes[i].runtimehash
hash := ctxt.Syms.ROLookup("go.link.pkghash."+l.Pkg, 0)
Addaddr(ctxt, pkghashes, hash)
}
Addaddr(ctxt, moduledata, pkghashes)
adduint(ctxt, moduledata, uint64(len(ctxt.Library)))
adduint(ctxt, moduledata, uint64(len(ctxt.Library)))
} else {
adduint(ctxt, moduledata, 0) // pluginpath
adduint(ctxt, moduledata, 0)
adduint(ctxt, moduledata, 0) // pkghashes slice
adduint(ctxt, moduledata, 0)
adduint(ctxt, moduledata, 0)
}
if len(ctxt.Shlibs) > 0 {
thismodulename := filepath.Base(*flagOutfile)
switch Buildmode {
case BuildmodeExe, BuildmodePIE:
// When linking an executable, outfile is just "a.out". Make
// it something slightly more comprehensible.
thismodulename = "the executable"
}
addgostring(ctxt, moduledata, "go.link.thismodulename", thismodulename)
modulehashes := ctxt.Syms.Lookup("go.link.abihashes", 0)
modulehashes.Attr |= AttrReachable
modulehashes.Attr |= AttrLocal
modulehashes.Type = SRODATA
for i, shlib := range ctxt.Shlibs {
// modulehashes[i].modulename
modulename := filepath.Base(shlib.Path)
addgostring(ctxt, modulehashes, fmt.Sprintf("go.link.libname.%d", i), modulename)
// modulehashes[i].linktimehash
addgostring(ctxt, modulehashes, fmt.Sprintf("go.link.linkhash.%d", i), string(shlib.Hash))
// modulehashes[i].runtimehash
abihash := ctxt.Syms.Lookup("go.link.abihash."+modulename, 0)
abihash.Attr |= AttrReachable
Addaddr(ctxt, modulehashes, abihash)
}
Addaddr(ctxt, moduledata, modulehashes)
adduint(ctxt, moduledata, uint64(len(ctxt.Shlibs)))
adduint(ctxt, moduledata, uint64(len(ctxt.Shlibs)))
}
// The rest of moduledata is zero initialized.
// When linking an object that does not contain the runtime we are
// creating the moduledata from scratch and it does not have a
// compiler-provided size, so read it from the type data.
moduledatatype := ctxt.Syms.ROLookup("type.runtime.moduledata", 0)
moduledata.Size = decodetypeSize(ctxt.Arch, moduledatatype)
Symgrow(moduledata, moduledata.Size)
lastmoduledatap := ctxt.Syms.Lookup("runtime.lastmoduledatap", 0)
if lastmoduledatap.Type != SDYNIMPORT {
lastmoduledatap.Type = SNOPTRDATA
lastmoduledatap.Size = 0 // overwrite existing value
Addaddr(ctxt, lastmoduledatap, moduledata)
}
}
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