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go / go / b675a75c3d7c221d8f5734203e25bd690a9a1f83 / . / src / cmd / link / internal / ld / elf.go
blob: 842570d5ef3a46badec1afe24e7f4c84c283646b [file] [log] [blame]
// Copyright 2009 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 ld
import (
"cmd/internal/notsha256"
"cmd/internal/objabi"
"cmd/internal/sys"
"cmd/link/internal/loader"
"cmd/link/internal/sym"
"debug/elf"
"encoding/binary"
"encoding/hex"
"fmt"
"internal/buildcfg"
"os"
"path/filepath"
"runtime"
"sort"
"strings"
)
/*
* Derived from:
* $FreeBSD: src/sys/sys/elf32.h,v 1.8.14.1 2005/12/30 22:13:58 marcel Exp $
* $FreeBSD: src/sys/sys/elf64.h,v 1.10.14.1 2005/12/30 22:13:58 marcel Exp $
* $FreeBSD: src/sys/sys/elf_common.h,v 1.15.8.1 2005/12/30 22:13:58 marcel Exp $
* $FreeBSD: src/sys/alpha/include/elf.h,v 1.14 2003/09/25 01:10:22 peter Exp $
* $FreeBSD: src/sys/amd64/include/elf.h,v 1.18 2004/08/03 08:21:48 dfr Exp $
* $FreeBSD: src/sys/arm/include/elf.h,v 1.5.2.1 2006/06/30 21:42:52 cognet Exp $
* $FreeBSD: src/sys/i386/include/elf.h,v 1.16 2004/08/02 19:12:17 dfr Exp $
* $FreeBSD: src/sys/powerpc/include/elf.h,v 1.7 2004/11/02 09:47:01 ssouhlal Exp $
* $FreeBSD: src/sys/sparc64/include/elf.h,v 1.12 2003/09/25 01:10:26 peter Exp $
*
* Copyright (c) 1996-1998 John D. Polstra. All rights reserved.
* Copyright (c) 2001 David E. O'Brien
* Portions Copyright 2009 The Go Authors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/*
* ELF definitions that are independent of architecture or word size.
*/
/*
* Note header. The ".note" section contains an array of notes. Each
* begins with this header, aligned to a word boundary. Immediately
* following the note header is n_namesz bytes of name, padded to the
* next word boundary. Then comes n_descsz bytes of descriptor, again
* padded to a word boundary. The values of n_namesz and n_descsz do
* not include the padding.
*/
type elfNote struct {
nNamesz uint32
nDescsz uint32
nType uint32
}
/* For accessing the fields of r_info. */
/* For constructing r_info from field values. */
/*
* Relocation types.
*/
const (
ARM_MAGIC_TRAMP_NUMBER = 0x5c000003
)
/*
* Symbol table entries.
*/
/* For accessing the fields of st_info. */
/* For constructing st_info from field values. */
/* For accessing the fields of st_other. */
/*
* ELF header.
*/
type ElfEhdr elf.Header64
/*
* Section header.
*/
type ElfShdr struct {
elf.Section64
shnum elf.SectionIndex
}
/*
* Program header.
*/
type ElfPhdr elf.ProgHeader
/* For accessing the fields of r_info. */
/* For constructing r_info from field values. */
/*
* Symbol table entries.
*/
/* For accessing the fields of st_info. */
/* For constructing st_info from field values. */
/* For accessing the fields of st_other. */
/*
* Go linker interface
*/
const (
ELF64HDRSIZE = 64
ELF64PHDRSIZE = 56
ELF64SHDRSIZE = 64
ELF64RELSIZE = 16
ELF64RELASIZE = 24
ELF64SYMSIZE = 24
ELF32HDRSIZE = 52
ELF32PHDRSIZE = 32
ELF32SHDRSIZE = 40
ELF32SYMSIZE = 16
ELF32RELSIZE = 8
)
/*
* The interface uses the 64-bit structures always,
* to avoid code duplication. The writers know how to
* marshal a 32-bit representation from the 64-bit structure.
*/
var Elfstrdat []byte
/*
* Total amount of space to reserve at the start of the file
* for Header, PHeaders, SHeaders, and interp.
* May waste some.
* On FreeBSD, cannot be larger than a page.
*/
const (
ELFRESERVE = 4096
)
/*
* We use the 64-bit data structures on both 32- and 64-bit machines
* in order to write the code just once. The 64-bit data structure is
* written in the 32-bit format on the 32-bit machines.
*/
const (
NSECT = 400
)
var (
Nelfsym = 1
elf64 bool
// Either ".rel" or ".rela" depending on which type of relocation the
// target platform uses.
elfRelType string
ehdr ElfEhdr
phdr [NSECT]*ElfPhdr
shdr [NSECT]*ElfShdr
interp string
)
// ELFArch includes target-specific hooks for ELF targets.
// This is initialized by the target-specific Init function
// called by the linker's main function in cmd/link/main.go.
type ELFArch struct {
// TODO: Document these fields.
Androiddynld string
Linuxdynld string
LinuxdynldMusl string
Freebsddynld string
Netbsddynld string
Openbsddynld string
Dragonflydynld string
Solarisdynld string
Reloc1 func(*Link, *OutBuf, *loader.Loader, loader.Sym, loader.ExtReloc, int, int64) bool
RelocSize uint32 // size of an ELF relocation record, must match Reloc1.
SetupPLT func(ctxt *Link, plt, gotplt *loader.SymbolBuilder, dynamic loader.Sym)
// DynamicReadOnly can be set to true to make the .dynamic
// section read-only. By default it is writable.
// This is used by MIPS targets.
DynamicReadOnly bool
}
type Elfstring struct {
s string
off int
}
var elfstr [100]Elfstring
var nelfstr int
var buildinfo []byte
/*
Initialize the global variable that describes the ELF header. It will be updated as
we write section and prog headers.
*/
func Elfinit(ctxt *Link) {
ctxt.IsELF = true
if ctxt.Arch.InFamily(sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X) {
elfRelType = ".rela"
} else {
elfRelType = ".rel"
}
switch ctxt.Arch.Family {
// 64-bit architectures
case sys.PPC64, sys.S390X:
if ctxt.Arch.ByteOrder == binary.BigEndian {
ehdr.Flags = 1 /* Version 1 ABI */
} else {
ehdr.Flags = 2 /* Version 2 ABI */
}
fallthrough
case sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS64, sys.RISCV64:
if ctxt.Arch.Family == sys.MIPS64 {
ehdr.Flags = 0x20000004 /* MIPS 3 CPIC */
}
if ctxt.Arch.Family == sys.Loong64 {
ehdr.Flags = 0x3 /* LoongArch lp64d */
}
if ctxt.Arch.Family == sys.RISCV64 {
ehdr.Flags = 0x4 /* RISCV Float ABI Double */
}
elf64 = true
ehdr.Phoff = ELF64HDRSIZE /* Must be ELF64HDRSIZE: first PHdr must follow ELF header */
ehdr.Shoff = ELF64HDRSIZE /* Will move as we add PHeaders */
ehdr.Ehsize = ELF64HDRSIZE /* Must be ELF64HDRSIZE */
ehdr.Phentsize = ELF64PHDRSIZE /* Must be ELF64PHDRSIZE */
ehdr.Shentsize = ELF64SHDRSIZE /* Must be ELF64SHDRSIZE */
// 32-bit architectures
case sys.ARM, sys.MIPS:
if ctxt.Arch.Family == sys.ARM {
// we use EABI on linux/arm, freebsd/arm, netbsd/arm.
if ctxt.HeadType == objabi.Hlinux || ctxt.HeadType == objabi.Hfreebsd || ctxt.HeadType == objabi.Hnetbsd {
// We set a value here that makes no indication of which
// float ABI the object uses, because this is information
// used by the dynamic linker to compare executables and
// shared libraries -- so it only matters for cgo calls, and
// the information properly comes from the object files
// produced by the host C compiler. parseArmAttributes in
// ldelf.go reads that information and updates this field as
// appropriate.
ehdr.Flags = 0x5000002 // has entry point, Version5 EABI
}
} else if ctxt.Arch.Family == sys.MIPS {
ehdr.Flags = 0x50001004 /* MIPS 32 CPIC O32*/
}
fallthrough
default:
ehdr.Phoff = ELF32HDRSIZE
/* Must be ELF32HDRSIZE: first PHdr must follow ELF header */
ehdr.Shoff = ELF32HDRSIZE /* Will move as we add PHeaders */
ehdr.Ehsize = ELF32HDRSIZE /* Must be ELF32HDRSIZE */
ehdr.Phentsize = ELF32PHDRSIZE /* Must be ELF32PHDRSIZE */
ehdr.Shentsize = ELF32SHDRSIZE /* Must be ELF32SHDRSIZE */
}
}
// Make sure PT_LOAD is aligned properly and
// that there is no gap,
// correct ELF loaders will do this implicitly,
// but buggy ELF loaders like the one in some
// versions of QEMU and UPX won't.
func fixElfPhdr(e *ElfPhdr) {
frag := int(e.Vaddr & (e.Align - 1))
e.Off -= uint64(frag)
e.Vaddr -= uint64(frag)
e.Paddr -= uint64(frag)
e.Filesz += uint64(frag)
e.Memsz += uint64(frag)
}
func elf64phdr(out *OutBuf, e *ElfPhdr) {
if e.Type == elf.PT_LOAD {
fixElfPhdr(e)
}
out.Write32(uint32(e.Type))
out.Write32(uint32(e.Flags))
out.Write64(e.Off)
out.Write64(e.Vaddr)
out.Write64(e.Paddr)
out.Write64(e.Filesz)
out.Write64(e.Memsz)
out.Write64(e.Align)
}
func elf32phdr(out *OutBuf, e *ElfPhdr) {
if e.Type == elf.PT_LOAD {
fixElfPhdr(e)
}
out.Write32(uint32(e.Type))
out.Write32(uint32(e.Off))
out.Write32(uint32(e.Vaddr))
out.Write32(uint32(e.Paddr))
out.Write32(uint32(e.Filesz))
out.Write32(uint32(e.Memsz))
out.Write32(uint32(e.Flags))
out.Write32(uint32(e.Align))
}
func elf64shdr(out *OutBuf, e *ElfShdr) {
out.Write32(e.Name)
out.Write32(uint32(e.Type))
out.Write64(uint64(e.Flags))
out.Write64(e.Addr)
out.Write64(e.Off)
out.Write64(e.Size)
out.Write32(e.Link)
out.Write32(e.Info)
out.Write64(e.Addralign)
out.Write64(e.Entsize)
}
func elf32shdr(out *OutBuf, e *ElfShdr) {
out.Write32(e.Name)
out.Write32(uint32(e.Type))
out.Write32(uint32(e.Flags))
out.Write32(uint32(e.Addr))
out.Write32(uint32(e.Off))
out.Write32(uint32(e.Size))
out.Write32(e.Link)
out.Write32(e.Info)
out.Write32(uint32(e.Addralign))
out.Write32(uint32(e.Entsize))
}
func elfwriteshdrs(out *OutBuf) uint32 {
if elf64 {
for i := 0; i < int(ehdr.Shnum); i++ {
elf64shdr(out, shdr[i])
}
return uint32(ehdr.Shnum) * ELF64SHDRSIZE
}
for i := 0; i < int(ehdr.Shnum); i++ {
elf32shdr(out, shdr[i])
}
return uint32(ehdr.Shnum) * ELF32SHDRSIZE
}
func elfsetstring(ctxt *Link, s loader.Sym, str string, off int) {
if nelfstr >= len(elfstr) {
ctxt.Errorf(s, "too many elf strings")
errorexit()
}
elfstr[nelfstr].s = str
elfstr[nelfstr].off = off
nelfstr++
}
func elfwritephdrs(out *OutBuf) uint32 {
if elf64 {
for i := 0; i < int(ehdr.Phnum); i++ {
elf64phdr(out, phdr[i])
}
return uint32(ehdr.Phnum) * ELF64PHDRSIZE
}
for i := 0; i < int(ehdr.Phnum); i++ {
elf32phdr(out, phdr[i])
}
return uint32(ehdr.Phnum) * ELF32PHDRSIZE
}
func newElfPhdr() *ElfPhdr {
e := new(ElfPhdr)
if ehdr.Phnum >= NSECT {
Errorf(nil, "too many phdrs")
} else {
phdr[ehdr.Phnum] = e
ehdr.Phnum++
}
if elf64 {
ehdr.Shoff += ELF64PHDRSIZE
} else {
ehdr.Shoff += ELF32PHDRSIZE
}
return e
}
func newElfShdr(name int64) *ElfShdr {
e := new(ElfShdr)
e.Name = uint32(name)
e.shnum = elf.SectionIndex(ehdr.Shnum)
if ehdr.Shnum >= NSECT {
Errorf(nil, "too many shdrs")
} else {
shdr[ehdr.Shnum] = e
ehdr.Shnum++
}
return e
}
func getElfEhdr() *ElfEhdr {
return &ehdr
}
func elf64writehdr(out *OutBuf) uint32 {
out.Write(ehdr.Ident[:])
out.Write16(uint16(ehdr.Type))
out.Write16(uint16(ehdr.Machine))
out.Write32(uint32(ehdr.Version))
out.Write64(ehdr.Entry)
out.Write64(ehdr.Phoff)
out.Write64(ehdr.Shoff)
out.Write32(ehdr.Flags)
out.Write16(ehdr.Ehsize)
out.Write16(ehdr.Phentsize)
out.Write16(ehdr.Phnum)
out.Write16(ehdr.Shentsize)
out.Write16(ehdr.Shnum)
out.Write16(ehdr.Shstrndx)
return ELF64HDRSIZE
}
func elf32writehdr(out *OutBuf) uint32 {
out.Write(ehdr.Ident[:])
out.Write16(uint16(ehdr.Type))
out.Write16(uint16(ehdr.Machine))
out.Write32(uint32(ehdr.Version))
out.Write32(uint32(ehdr.Entry))
out.Write32(uint32(ehdr.Phoff))
out.Write32(uint32(ehdr.Shoff))
out.Write32(ehdr.Flags)
out.Write16(ehdr.Ehsize)
out.Write16(ehdr.Phentsize)
out.Write16(ehdr.Phnum)
out.Write16(ehdr.Shentsize)
out.Write16(ehdr.Shnum)
out.Write16(ehdr.Shstrndx)
return ELF32HDRSIZE
}
func elfwritehdr(out *OutBuf) uint32 {
if elf64 {
return elf64writehdr(out)
}
return elf32writehdr(out)
}
/* Taken directly from the definition document for ELF64. */
func elfhash(name string) uint32 {
var h uint32
for i := 0; i < len(name); i++ {
h = (h << 4) + uint32(name[i])
if g := h & 0xf0000000; g != 0 {
h ^= g >> 24
}
h &= 0x0fffffff
}
return h
}
func elfWriteDynEntSym(ctxt *Link, s *loader.SymbolBuilder, tag elf.DynTag, t loader.Sym) {
Elfwritedynentsymplus(ctxt, s, tag, t, 0)
}
func Elfwritedynent(arch *sys.Arch, s *loader.SymbolBuilder, tag elf.DynTag, val uint64) {
if elf64 {
s.AddUint64(arch, uint64(tag))
s.AddUint64(arch, val)
} else {
s.AddUint32(arch, uint32(tag))
s.AddUint32(arch, uint32(val))
}
}
func Elfwritedynentsymplus(ctxt *Link, s *loader.SymbolBuilder, tag elf.DynTag, t loader.Sym, add int64) {
if elf64 {
s.AddUint64(ctxt.Arch, uint64(tag))
} else {
s.AddUint32(ctxt.Arch, uint32(tag))
}
s.AddAddrPlus(ctxt.Arch, t, add)
}
func elfwritedynentsymsize(ctxt *Link, s *loader.SymbolBuilder, tag elf.DynTag, t loader.Sym) {
if elf64 {
s.AddUint64(ctxt.Arch, uint64(tag))
} else {
s.AddUint32(ctxt.Arch, uint32(tag))
}
s.AddSize(ctxt.Arch, t)
}
func elfinterp(sh *ElfShdr, startva uint64, resoff uint64, p string) int {
interp = p
n := len(interp) + 1
sh.Addr = startva + resoff - uint64(n)
sh.Off = resoff - uint64(n)
sh.Size = uint64(n)
return n
}
func elfwriteinterp(out *OutBuf) int {
sh := elfshname(".interp")
out.SeekSet(int64(sh.Off))
out.WriteString(interp)
out.Write8(0)
return int(sh.Size)
}
// member of .gnu.attributes of MIPS for fpAbi
const (
// No floating point is present in the module (default)
MIPS_FPABI_NONE = 0
// FP code in the module uses the FP32 ABI for a 32-bit ABI
MIPS_FPABI_ANY = 1
// FP code in the module only uses single precision ABI
MIPS_FPABI_SINGLE = 2
// FP code in the module uses soft-float ABI
MIPS_FPABI_SOFT = 3
// FP code in the module assumes an FPU with FR=1 and has 12
// callee-saved doubles. Historic, no longer supported.
MIPS_FPABI_HIST = 4
// FP code in the module uses the FPXX ABI
MIPS_FPABI_FPXX = 5
// FP code in the module uses the FP64 ABI
MIPS_FPABI_FP64 = 6
// FP code in the module uses the FP64A ABI
MIPS_FPABI_FP64A = 7
)
func elfMipsAbiFlags(sh *ElfShdr, startva uint64, resoff uint64) int {
n := 24
sh.Addr = startva + resoff - uint64(n)
sh.Off = resoff - uint64(n)
sh.Size = uint64(n)
sh.Type = uint32(elf.SHT_MIPS_ABIFLAGS)
sh.Flags = uint64(elf.SHF_ALLOC)
return n
}
// Layout is given by this C definition:
//
// typedef struct
// {
// /* Version of flags structure. */
// uint16_t version;
// /* The level of the ISA: 1-5, 32, 64. */
// uint8_t isa_level;
// /* The revision of ISA: 0 for MIPS V and below, 1-n otherwise. */
// uint8_t isa_rev;
// /* The size of general purpose registers. */
// uint8_t gpr_size;
// /* The size of co-processor 1 registers. */
// uint8_t cpr1_size;
// /* The size of co-processor 2 registers. */
// uint8_t cpr2_size;
// /* The floating-point ABI. */
// uint8_t fp_abi;
// /* Processor-specific extension. */
// uint32_t isa_ext;
// /* Mask of ASEs used. */
// uint32_t ases;
// /* Mask of general flags. */
// uint32_t flags1;
// uint32_t flags2;
// } Elf_Internal_ABIFlags_v0;
func elfWriteMipsAbiFlags(ctxt *Link) int {
sh := elfshname(".MIPS.abiflags")
ctxt.Out.SeekSet(int64(sh.Off))
ctxt.Out.Write16(0) // version
ctxt.Out.Write8(32) // isaLevel
ctxt.Out.Write8(1) // isaRev
ctxt.Out.Write8(1) // gprSize
ctxt.Out.Write8(1) // cpr1Size
ctxt.Out.Write8(0) // cpr2Size
if buildcfg.GOMIPS == "softfloat" {
ctxt.Out.Write8(MIPS_FPABI_SOFT) // fpAbi
} else {
// Go cannot make sure non odd-number-fpr is used (ie, in load a double from memory).
// So, we mark the object is MIPS I style paired float/double register scheme,
// aka MIPS_FPABI_ANY. If we mark the object as FPXX, the kernel may use FR=1 mode,
// then we meet some problem.
// Note: MIPS_FPABI_ANY is bad naming: in fact it is MIPS I style FPR usage.
// It is not for 'ANY'.
// TODO: switch to FPXX after be sure that no odd-number-fpr is used.
ctxt.Out.Write8(MIPS_FPABI_ANY) // fpAbi
}
ctxt.Out.Write32(0) // isaExt
ctxt.Out.Write32(0) // ases
ctxt.Out.Write32(0) // flags1
ctxt.Out.Write32(0) // flags2
return int(sh.Size)
}
func elfnote(sh *ElfShdr, startva uint64, resoff uint64, sizes ...int) int {
n := resoff % 4
// if section contains multiple notes (as is the case with FreeBSD signature),
// multiple note sizes can be specified
for _, sz := range sizes {
n += 3*4 + uint64(sz)
}
sh.Type = uint32(elf.SHT_NOTE)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Addralign = 4
sh.Addr = startva + resoff - n
sh.Off = resoff - n
sh.Size = n - resoff%4
return int(n)
}
func elfwritenotehdr(out *OutBuf, str string, namesz uint32, descsz uint32, tag uint32) *ElfShdr {
sh := elfshname(str)
// Write Elf_Note header.
out.SeekSet(int64(sh.Off))
out.Write32(namesz)
out.Write32(descsz)
out.Write32(tag)
return sh
}
// NetBSD Signature (as per sys/exec_elf.h)
const (
ELF_NOTE_NETBSD_NAMESZ = 7
ELF_NOTE_NETBSD_DESCSZ = 4
ELF_NOTE_NETBSD_TAG = 1
ELF_NOTE_NETBSD_VERSION = 700000000 /* NetBSD 7.0 */
)
var ELF_NOTE_NETBSD_NAME = []byte("NetBSD\x00")
func elfnetbsdsig(sh *ElfShdr, startva uint64, resoff uint64) int {
n := int(Rnd(ELF_NOTE_NETBSD_NAMESZ, 4) + Rnd(ELF_NOTE_NETBSD_DESCSZ, 4))
return elfnote(sh, startva, resoff, n)
}
func elfwritenetbsdsig(out *OutBuf) int {
// Write Elf_Note header.
sh := elfwritenotehdr(out, ".note.netbsd.ident", ELF_NOTE_NETBSD_NAMESZ, ELF_NOTE_NETBSD_DESCSZ, ELF_NOTE_NETBSD_TAG)
if sh == nil {
return 0
}
// Followed by NetBSD string and version.
out.Write(ELF_NOTE_NETBSD_NAME)
out.Write8(0)
out.Write32(ELF_NOTE_NETBSD_VERSION)
return int(sh.Size)
}
// The race detector can't handle ASLR (address space layout randomization).
// ASLR is on by default for NetBSD, so we turn the ASLR off explicitly
// using a magic elf Note when building race binaries.
func elfnetbsdpax(sh *ElfShdr, startva uint64, resoff uint64) int {
n := int(Rnd(4, 4) + Rnd(4, 4))
return elfnote(sh, startva, resoff, n)
}
func elfwritenetbsdpax(out *OutBuf) int {
sh := elfwritenotehdr(out, ".note.netbsd.pax", 4 /* length of PaX\x00 */, 4 /* length of flags */, 0x03 /* PaX type */)
if sh == nil {
return 0
}
out.Write([]byte("PaX\x00"))
out.Write32(0x20) // 0x20 = Force disable ASLR
return int(sh.Size)
}
// OpenBSD Signature
const (
ELF_NOTE_OPENBSD_NAMESZ = 8
ELF_NOTE_OPENBSD_DESCSZ = 4
ELF_NOTE_OPENBSD_TAG = 1
ELF_NOTE_OPENBSD_VERSION = 0
)
var ELF_NOTE_OPENBSD_NAME = []byte("OpenBSD\x00")
func elfopenbsdsig(sh *ElfShdr, startva uint64, resoff uint64) int {
n := ELF_NOTE_OPENBSD_NAMESZ + ELF_NOTE_OPENBSD_DESCSZ
return elfnote(sh, startva, resoff, n)
}
func elfwriteopenbsdsig(out *OutBuf) int {
// Write Elf_Note header.
sh := elfwritenotehdr(out, ".note.openbsd.ident", ELF_NOTE_OPENBSD_NAMESZ, ELF_NOTE_OPENBSD_DESCSZ, ELF_NOTE_OPENBSD_TAG)
if sh == nil {
return 0
}
// Followed by OpenBSD string and version.
out.Write(ELF_NOTE_OPENBSD_NAME)
out.Write32(ELF_NOTE_OPENBSD_VERSION)
return int(sh.Size)
}
// FreeBSD Signature (as per sys/elf_common.h)
const (
ELF_NOTE_FREEBSD_NAMESZ = 8
ELF_NOTE_FREEBSD_DESCSZ = 4
ELF_NOTE_FREEBSD_ABI_TAG = 1
ELF_NOTE_FREEBSD_NOINIT_TAG = 2
ELF_NOTE_FREEBSD_FEATURE_CTL_TAG = 4
ELF_NOTE_FREEBSD_VERSION = 1203000 // 12.3-RELEASE
ELF_NOTE_FREEBSD_FCTL_ASLR_DISABLE = 0x1
)
const ELF_NOTE_FREEBSD_NAME = "FreeBSD\x00"
func elffreebsdsig(sh *ElfShdr, startva uint64, resoff uint64) int {
n := ELF_NOTE_FREEBSD_NAMESZ + ELF_NOTE_FREEBSD_DESCSZ
// FreeBSD signature section contains 3 equally sized notes
return elfnote(sh, startva, resoff, n, n, n)
}
// elfwritefreebsdsig writes FreeBSD .note section.
//
// See https://www.netbsd.org/docs/kernel/elf-notes.html for the description of
// a Note element format and
// https://github.com/freebsd/freebsd-src/blob/main/sys/sys/elf_common.h#L790
// for the FreeBSD-specific values.
func elfwritefreebsdsig(out *OutBuf) int {
sh := elfshname(".note.tag")
if sh == nil {
return 0
}
out.SeekSet(int64(sh.Off))
// NT_FREEBSD_ABI_TAG
out.Write32(ELF_NOTE_FREEBSD_NAMESZ)
out.Write32(ELF_NOTE_FREEBSD_DESCSZ)
out.Write32(ELF_NOTE_FREEBSD_ABI_TAG)
out.WriteString(ELF_NOTE_FREEBSD_NAME)
out.Write32(ELF_NOTE_FREEBSD_VERSION)
// NT_FREEBSD_NOINIT_TAG
out.Write32(ELF_NOTE_FREEBSD_NAMESZ)
out.Write32(ELF_NOTE_FREEBSD_DESCSZ)
out.Write32(ELF_NOTE_FREEBSD_NOINIT_TAG)
out.WriteString(ELF_NOTE_FREEBSD_NAME)
out.Write32(0)
// NT_FREEBSD_FEATURE_CTL
out.Write32(ELF_NOTE_FREEBSD_NAMESZ)
out.Write32(ELF_NOTE_FREEBSD_DESCSZ)
out.Write32(ELF_NOTE_FREEBSD_FEATURE_CTL_TAG)
out.WriteString(ELF_NOTE_FREEBSD_NAME)
if *flagRace {
// The race detector can't handle ASLR, turn the ASLR off when compiling with -race.
out.Write32(ELF_NOTE_FREEBSD_FCTL_ASLR_DISABLE)
} else {
out.Write32(0)
}
return int(sh.Size)
}
func addbuildinfo(val string) {
if !strings.HasPrefix(val, "0x") {
Exitf("-B argument must start with 0x: %s", val)
}
ov := val
val = val[2:]
const maxLen = 32
if hex.DecodedLen(len(val)) > maxLen {
Exitf("-B option too long (max %d digits): %s", maxLen, ov)
}
b, err := hex.DecodeString(val)
if err != nil {
if err == hex.ErrLength {
Exitf("-B argument must have even number of digits: %s", ov)
}
if inv, ok := err.(hex.InvalidByteError); ok {
Exitf("-B argument contains invalid hex digit %c: %s", byte(inv), ov)
}
Exitf("-B argument contains invalid hex: %s", ov)
}
buildinfo = b
}
// Build info note
const (
ELF_NOTE_BUILDINFO_NAMESZ = 4
ELF_NOTE_BUILDINFO_TAG = 3
)
var ELF_NOTE_BUILDINFO_NAME = []byte("GNU\x00")
func elfbuildinfo(sh *ElfShdr, startva uint64, resoff uint64) int {
n := int(ELF_NOTE_BUILDINFO_NAMESZ + Rnd(int64(len(buildinfo)), 4))
return elfnote(sh, startva, resoff, n)
}
func elfgobuildid(sh *ElfShdr, startva uint64, resoff uint64) int {
n := len(ELF_NOTE_GO_NAME) + int(Rnd(int64(len(*flagBuildid)), 4))
return elfnote(sh, startva, resoff, n)
}
func elfwritebuildinfo(out *OutBuf) int {
sh := elfwritenotehdr(out, ".note.gnu.build-id", ELF_NOTE_BUILDINFO_NAMESZ, uint32(len(buildinfo)), ELF_NOTE_BUILDINFO_TAG)
if sh == nil {
return 0
}
out.Write(ELF_NOTE_BUILDINFO_NAME)
out.Write(buildinfo)
var zero = make([]byte, 4)
out.Write(zero[:int(Rnd(int64(len(buildinfo)), 4)-int64(len(buildinfo)))])
return int(sh.Size)
}
func elfwritegobuildid(out *OutBuf) int {
sh := elfwritenotehdr(out, ".note.go.buildid", uint32(len(ELF_NOTE_GO_NAME)), uint32(len(*flagBuildid)), ELF_NOTE_GOBUILDID_TAG)
if sh == nil {
return 0
}
out.Write(ELF_NOTE_GO_NAME)
out.Write([]byte(*flagBuildid))
var zero = make([]byte, 4)
out.Write(zero[:int(Rnd(int64(len(*flagBuildid)), 4)-int64(len(*flagBuildid)))])
return int(sh.Size)
}
// Go specific notes
const (
ELF_NOTE_GOPKGLIST_TAG = 1
ELF_NOTE_GOABIHASH_TAG = 2
ELF_NOTE_GODEPS_TAG = 3
ELF_NOTE_GOBUILDID_TAG = 4
)
var ELF_NOTE_GO_NAME = []byte("Go\x00\x00")
var elfverneed int
type Elfaux struct {
next *Elfaux
num int
vers string
}
type Elflib struct {
next *Elflib
aux *Elfaux
file string
}
func addelflib(list **Elflib, file string, vers string) *Elfaux {
var lib *Elflib
for lib = *list; lib != nil; lib = lib.next {
if lib.file == file {
goto havelib
}
}
lib = new(Elflib)
lib.next = *list
lib.file = file
*list = lib
havelib:
for aux := lib.aux; aux != nil; aux = aux.next {
if aux.vers == vers {
return aux
}
}
aux := new(Elfaux)
aux.next = lib.aux
aux.vers = vers
lib.aux = aux
return aux
}
func elfdynhash(ctxt *Link) {
if !ctxt.IsELF {
return
}
nsym := Nelfsym
ldr := ctxt.loader
s := ldr.CreateSymForUpdate(".hash", 0)
s.SetType(sym.SELFROSECT)
i := nsym
nbucket := 1
for i > 0 {
nbucket++
i >>= 1
}
var needlib *Elflib
need := make([]*Elfaux, nsym)
chain := make([]uint32, nsym)
buckets := make([]uint32, nbucket)
for _, sy := range ldr.DynidSyms() {
dynid := ldr.SymDynid(sy)
if ldr.SymDynimpvers(sy) != "" {
need[dynid] = addelflib(&needlib, ldr.SymDynimplib(sy), ldr.SymDynimpvers(sy))
}
name := ldr.SymExtname(sy)
hc := elfhash(name)
b := hc % uint32(nbucket)
chain[dynid] = buckets[b]
buckets[b] = uint32(dynid)
}
// s390x (ELF64) hash table entries are 8 bytes
if ctxt.Arch.Family == sys.S390X {
s.AddUint64(ctxt.Arch, uint64(nbucket))
s.AddUint64(ctxt.Arch, uint64(nsym))
for i := 0; i < nbucket; i++ {
s.AddUint64(ctxt.Arch, uint64(buckets[i]))
}
for i := 0; i < nsym; i++ {
s.AddUint64(ctxt.Arch, uint64(chain[i]))
}
} else {
s.AddUint32(ctxt.Arch, uint32(nbucket))
s.AddUint32(ctxt.Arch, uint32(nsym))
for i := 0; i < nbucket; i++ {
s.AddUint32(ctxt.Arch, buckets[i])
}
for i := 0; i < nsym; i++ {
s.AddUint32(ctxt.Arch, chain[i])
}
}
dynstr := ldr.CreateSymForUpdate(".dynstr", 0)
// version symbols
gnuVersionR := ldr.CreateSymForUpdate(".gnu.version_r", 0)
s = gnuVersionR
i = 2
nfile := 0
for l := needlib; l != nil; l = l.next {
nfile++
// header
s.AddUint16(ctxt.Arch, 1) // table version
j := 0
for x := l.aux; x != nil; x = x.next {
j++
}
s.AddUint16(ctxt.Arch, uint16(j)) // aux count
s.AddUint32(ctxt.Arch, uint32(dynstr.Addstring(l.file))) // file string offset
s.AddUint32(ctxt.Arch, 16) // offset from header to first aux
if l.next != nil {
s.AddUint32(ctxt.Arch, 16+uint32(j)*16) // offset from this header to next
} else {
s.AddUint32(ctxt.Arch, 0)
}
for x := l.aux; x != nil; x = x.next {
x.num = i
i++
// aux struct
s.AddUint32(ctxt.Arch, elfhash(x.vers)) // hash
s.AddUint16(ctxt.Arch, 0) // flags
s.AddUint16(ctxt.Arch, uint16(x.num)) // other - index we refer to this by
s.AddUint32(ctxt.Arch, uint32(dynstr.Addstring(x.vers))) // version string offset
if x.next != nil {
s.AddUint32(ctxt.Arch, 16) // offset from this aux to next
} else {
s.AddUint32(ctxt.Arch, 0)
}
}
}
// version references
gnuVersion := ldr.CreateSymForUpdate(".gnu.version", 0)
s = gnuVersion
for i := 0; i < nsym; i++ {
if i == 0 {
s.AddUint16(ctxt.Arch, 0) // first entry - no symbol
} else if need[i] == nil {
s.AddUint16(ctxt.Arch, 1) // global
} else {
s.AddUint16(ctxt.Arch, uint16(need[i].num))
}
}
s = ldr.CreateSymForUpdate(".dynamic", 0)
if ctxt.BuildMode == BuildModePIE {
// https://github.com/bminor/glibc/blob/895ef79e04a953cac1493863bcae29ad85657ee1/elf/elf.h#L986
const DTFLAGS_1_PIE = 0x08000000
Elfwritedynent(ctxt.Arch, s, elf.DT_FLAGS_1, uint64(DTFLAGS_1_PIE))
}
elfverneed = nfile
if elfverneed != 0 {
elfWriteDynEntSym(ctxt, s, elf.DT_VERNEED, gnuVersionR.Sym())
Elfwritedynent(ctxt.Arch, s, elf.DT_VERNEEDNUM, uint64(nfile))
elfWriteDynEntSym(ctxt, s, elf.DT_VERSYM, gnuVersion.Sym())
}
sy := ldr.CreateSymForUpdate(elfRelType+".plt", 0)
if sy.Size() > 0 {
if elfRelType == ".rela" {
Elfwritedynent(ctxt.Arch, s, elf.DT_PLTREL, uint64(elf.DT_RELA))
} else {
Elfwritedynent(ctxt.Arch, s, elf.DT_PLTREL, uint64(elf.DT_REL))
}
elfwritedynentsymsize(ctxt, s, elf.DT_PLTRELSZ, sy.Sym())
elfWriteDynEntSym(ctxt, s, elf.DT_JMPREL, sy.Sym())
}
Elfwritedynent(ctxt.Arch, s, elf.DT_NULL, 0)
}
func elfphload(seg *sym.Segment) *ElfPhdr {
ph := newElfPhdr()
ph.Type = elf.PT_LOAD
if seg.Rwx&4 != 0 {
ph.Flags |= elf.PF_R
}
if seg.Rwx&2 != 0 {
ph.Flags |= elf.PF_W
}
if seg.Rwx&1 != 0 {
ph.Flags |= elf.PF_X
}
ph.Vaddr = seg.Vaddr
ph.Paddr = seg.Vaddr
ph.Memsz = seg.Length
ph.Off = seg.Fileoff
ph.Filesz = seg.Filelen
ph.Align = uint64(*FlagRound)
return ph
}
func elfphrelro(seg *sym.Segment) {
ph := newElfPhdr()
ph.Type = elf.PT_GNU_RELRO
ph.Vaddr = seg.Vaddr
ph.Paddr = seg.Vaddr
ph.Memsz = seg.Length
ph.Off = seg.Fileoff
ph.Filesz = seg.Filelen
ph.Align = uint64(*FlagRound)
}
func elfshname(name string) *ElfShdr {
for i := 0; i < nelfstr; i++ {
if name != elfstr[i].s {
continue
}
off := elfstr[i].off
for i = 0; i < int(ehdr.Shnum); i++ {
sh := shdr[i]
if sh.Name == uint32(off) {
return sh
}
}
return newElfShdr(int64(off))
}
Exitf("cannot find elf name %s", name)
return nil
}
// Create an ElfShdr for the section with name.
// Create a duplicate if one already exists with that name.
func elfshnamedup(name string) *ElfShdr {
for i := 0; i < nelfstr; i++ {
if name == elfstr[i].s {
off := elfstr[i].off
return newElfShdr(int64(off))
}
}
Errorf(nil, "cannot find elf name %s", name)
errorexit()
return nil
}
func elfshalloc(sect *sym.Section) *ElfShdr {
sh := elfshname(sect.Name)
sect.Elfsect = sh
return sh
}
func elfshbits(linkmode LinkMode, sect *sym.Section) *ElfShdr {
var sh *ElfShdr
if sect.Name == ".text" {
if sect.Elfsect == nil {
sect.Elfsect = elfshnamedup(sect.Name)
}
sh = sect.Elfsect.(*ElfShdr)
} else {
sh = elfshalloc(sect)
}
// If this section has already been set up as a note, we assume type_ and
// flags are already correct, but the other fields still need filling in.
if sh.Type == uint32(elf.SHT_NOTE) {
if linkmode != LinkExternal {
// TODO(mwhudson): the approach here will work OK when
// linking internally for notes that we want to be included
// in a loadable segment (e.g. the abihash note) but not for
// notes that we do not want to be mapped (e.g. the package
// list note). The real fix is probably to define new values
// for Symbol.Type corresponding to mapped and unmapped notes
// and handle them in dodata().
Errorf(nil, "sh.Type == SHT_NOTE in elfshbits when linking internally")
}
sh.Addralign = uint64(sect.Align)
sh.Size = sect.Length
sh.Off = sect.Seg.Fileoff + sect.Vaddr - sect.Seg.Vaddr
return sh
}
if sh.Type > 0 {
return sh
}
if sect.Vaddr < sect.Seg.Vaddr+sect.Seg.Filelen {
switch sect.Name {
case ".init_array":
sh.Type = uint32(elf.SHT_INIT_ARRAY)
default:
sh.Type = uint32(elf.SHT_PROGBITS)
}
} else {
sh.Type = uint32(elf.SHT_NOBITS)
}
sh.Flags = uint64(elf.SHF_ALLOC)
if sect.Rwx&1 != 0 {
sh.Flags |= uint64(elf.SHF_EXECINSTR)
}
if sect.Rwx&2 != 0 {
sh.Flags |= uint64(elf.SHF_WRITE)
}
if sect.Name == ".tbss" {
sh.Flags |= uint64(elf.SHF_TLS)
sh.Type = uint32(elf.SHT_NOBITS)
}
if linkmode != LinkExternal {
sh.Addr = sect.Vaddr
}
if strings.HasPrefix(sect.Name, ".debug") || strings.HasPrefix(sect.Name, ".zdebug") {
sh.Flags = 0
sh.Addr = 0
if sect.Compressed {
sh.Flags |= uint64(elf.SHF_COMPRESSED)
}
}
sh.Addralign = uint64(sect.Align)
sh.Size = sect.Length
if sect.Name != ".tbss" {
sh.Off = sect.Seg.Fileoff + sect.Vaddr - sect.Seg.Vaddr
}
return sh
}
func elfshreloc(arch *sys.Arch, sect *sym.Section) *ElfShdr {
// If main section is SHT_NOBITS, nothing to relocate.
// Also nothing to relocate in .shstrtab or notes.
if sect.Vaddr >= sect.Seg.Vaddr+sect.Seg.Filelen {
return nil
}
if sect.Name == ".shstrtab" || sect.Name == ".tbss" {
return nil
}
if sect.Elfsect.(*ElfShdr).Type == uint32(elf.SHT_NOTE) {
return nil
}
typ := elf.SHT_REL
if elfRelType == ".rela" {
typ = elf.SHT_RELA
}
sh := elfshname(elfRelType + sect.Name)
// There could be multiple text sections but each needs
// its own .rela.text.
if sect.Name == ".text" {
if sh.Info != 0 && sh.Info != uint32(sect.Elfsect.(*ElfShdr).shnum) {
sh = elfshnamedup(elfRelType + sect.Name)
}
}
sh.Type = uint32(typ)
sh.Entsize = uint64(arch.RegSize) * 2
if typ == elf.SHT_RELA {
sh.Entsize += uint64(arch.RegSize)
}
sh.Link = uint32(elfshname(".symtab").shnum)
sh.Info = uint32(sect.Elfsect.(*ElfShdr).shnum)
sh.Off = sect.Reloff
sh.Size = sect.Rellen
sh.Addralign = uint64(arch.RegSize)
return sh
}
func elfrelocsect(ctxt *Link, out *OutBuf, sect *sym.Section, syms []loader.Sym) {
// If main section is SHT_NOBITS, nothing to relocate.
// Also nothing to relocate in .shstrtab.
if sect.Vaddr >= sect.Seg.Vaddr+sect.Seg.Filelen {
return
}
if sect.Name == ".shstrtab" {
return
}
ldr := ctxt.loader
for i, s := range syms {
if !ldr.AttrReachable(s) {
panic("should never happen")
}
if uint64(ldr.SymValue(s)) >= sect.Vaddr {
syms = syms[i:]
break
}
}
eaddr := sect.Vaddr + sect.Length
for _, s := range syms {
if !ldr.AttrReachable(s) {
continue
}
if ldr.SymValue(s) >= int64(eaddr) {
break
}
// Compute external relocations on the go, and pass to
// ELF.Reloc1 to stream out.
relocs := ldr.Relocs(s)
for ri := 0; ri < relocs.Count(); ri++ {
r := relocs.At(ri)
rr, ok := extreloc(ctxt, ldr, s, r)
if !ok {
continue
}
if rr.Xsym == 0 {
ldr.Errorf(s, "missing xsym in relocation")
continue
}
esr := ElfSymForReloc(ctxt, rr.Xsym)
if esr == 0 {
ldr.Errorf(s, "reloc %d (%s) to non-elf symbol %s (outer=%s) %d (%s)", r.Type(), sym.RelocName(ctxt.Arch, r.Type()), ldr.SymName(r.Sym()), ldr.SymName(rr.Xsym), ldr.SymType(r.Sym()), ldr.SymType(r.Sym()).String())
}
if !ldr.AttrReachable(rr.Xsym) {
ldr.Errorf(s, "unreachable reloc %d (%s) target %v", r.Type(), sym.RelocName(ctxt.Arch, r.Type()), ldr.SymName(rr.Xsym))
}
if !thearch.ELF.Reloc1(ctxt, out, ldr, s, rr, ri, int64(uint64(ldr.SymValue(s)+int64(r.Off()))-sect.Vaddr)) {
ldr.Errorf(s, "unsupported obj reloc %d (%s)/%d to %s", r.Type(), sym.RelocName(ctxt.Arch, r.Type()), r.Siz(), ldr.SymName(r.Sym()))
}
}
}
// sanity check
if uint64(out.Offset()) != sect.Reloff+sect.Rellen {
panic(fmt.Sprintf("elfrelocsect: size mismatch %d != %d + %d", out.Offset(), sect.Reloff, sect.Rellen))
}
}
func elfEmitReloc(ctxt *Link) {
for ctxt.Out.Offset()&7 != 0 {
ctxt.Out.Write8(0)
}
sizeExtRelocs(ctxt, thearch.ELF.RelocSize)
relocSect, wg := relocSectFn(ctxt, elfrelocsect)
for _, sect := range Segtext.Sections {
if sect.Name == ".text" {
relocSect(ctxt, sect, ctxt.Textp)
} else {
relocSect(ctxt, sect, ctxt.datap)
}
}
for _, sect := range Segrodata.Sections {
relocSect(ctxt, sect, ctxt.datap)
}
for _, sect := range Segrelrodata.Sections {
relocSect(ctxt, sect, ctxt.datap)
}
for _, sect := range Segdata.Sections {
relocSect(ctxt, sect, ctxt.datap)
}
for i := 0; i < len(Segdwarf.Sections); i++ {
sect := Segdwarf.Sections[i]
si := dwarfp[i]
if si.secSym() != loader.Sym(sect.Sym) ||
ctxt.loader.SymSect(si.secSym()) != sect {
panic("inconsistency between dwarfp and Segdwarf")
}
relocSect(ctxt, sect, si.syms)
}
wg.Wait()
}
func addgonote(ctxt *Link, sectionName string, tag uint32, desc []byte) {
ldr := ctxt.loader
s := ldr.CreateSymForUpdate(sectionName, 0)
s.SetType(sym.SELFROSECT)
// namesz
s.AddUint32(ctxt.Arch, uint32(len(ELF_NOTE_GO_NAME)))
// descsz
s.AddUint32(ctxt.Arch, uint32(len(desc)))
// tag
s.AddUint32(ctxt.Arch, tag)
// name + padding
s.AddBytes(ELF_NOTE_GO_NAME)
for len(s.Data())%4 != 0 {
s.AddUint8(0)
}
// desc + padding
s.AddBytes(desc)
for len(s.Data())%4 != 0 {
s.AddUint8(0)
}
s.SetSize(int64(len(s.Data())))
s.SetAlign(4)
}
func (ctxt *Link) doelf() {
ldr := ctxt.loader
/* predefine strings we need for section headers */
shstrtab := ldr.CreateSymForUpdate(".shstrtab", 0)
shstrtab.SetType(sym.SELFROSECT)
shstrtab.Addstring("")
shstrtab.Addstring(".text")
shstrtab.Addstring(".noptrdata")
shstrtab.Addstring(".data")
shstrtab.Addstring(".bss")
shstrtab.Addstring(".noptrbss")
shstrtab.Addstring(".go.fuzzcntrs")
shstrtab.Addstring(".go.buildinfo")
if ctxt.IsMIPS() {
shstrtab.Addstring(".MIPS.abiflags")
shstrtab.Addstring(".gnu.attributes")
}
// generate .tbss section for dynamic internal linker or external
// linking, so that various binutils could correctly calculate
// PT_TLS size. See https://golang.org/issue/5200.
if !*FlagD || ctxt.IsExternal() {
shstrtab.Addstring(".tbss")
}
if ctxt.IsNetbsd() {
shstrtab.Addstring(".note.netbsd.ident")
if *flagRace {
shstrtab.Addstring(".note.netbsd.pax")
}
}
if ctxt.IsOpenbsd() {
shstrtab.Addstring(".note.openbsd.ident")
}
if ctxt.IsFreebsd() {
shstrtab.Addstring(".note.tag")
}
if len(buildinfo) > 0 {
shstrtab.Addstring(".note.gnu.build-id")
}
if *flagBuildid != "" {
shstrtab.Addstring(".note.go.buildid")
}
shstrtab.Addstring(".elfdata")
shstrtab.Addstring(".rodata")
// See the comment about data.rel.ro.FOO section names in data.go.
relro_prefix := ""
if ctxt.UseRelro() {
shstrtab.Addstring(".data.rel.ro")
relro_prefix = ".data.rel.ro"
}
shstrtab.Addstring(relro_prefix + ".typelink")
shstrtab.Addstring(relro_prefix + ".itablink")
shstrtab.Addstring(relro_prefix + ".gosymtab")
shstrtab.Addstring(relro_prefix + ".gopclntab")
if ctxt.IsExternal() {
*FlagD = true
shstrtab.Addstring(elfRelType + ".text")
shstrtab.Addstring(elfRelType + ".rodata")
shstrtab.Addstring(elfRelType + relro_prefix + ".typelink")
shstrtab.Addstring(elfRelType + relro_prefix + ".itablink")
shstrtab.Addstring(elfRelType + relro_prefix + ".gosymtab")
shstrtab.Addstring(elfRelType + relro_prefix + ".gopclntab")
shstrtab.Addstring(elfRelType + ".noptrdata")
shstrtab.Addstring(elfRelType + ".data")
if ctxt.UseRelro() {
shstrtab.Addstring(elfRelType + ".data.rel.ro")
}
shstrtab.Addstring(elfRelType + ".go.buildinfo")
if ctxt.IsMIPS() {
shstrtab.Addstring(elfRelType + ".MIPS.abiflags")
shstrtab.Addstring(elfRelType + ".gnu.attributes")
}
// add a .note.GNU-stack section to mark the stack as non-executable
shstrtab.Addstring(".note.GNU-stack")
if ctxt.IsShared() {
shstrtab.Addstring(".note.go.abihash")
shstrtab.Addstring(".note.go.pkg-list")
shstrtab.Addstring(".note.go.deps")
}
}
hasinitarr := ctxt.linkShared
/* shared library initializer */
switch ctxt.BuildMode {
case BuildModeCArchive, BuildModeCShared, BuildModeShared, BuildModePlugin:
hasinitarr = true
}
if hasinitarr {
shstrtab.Addstring(".init_array")
shstrtab.Addstring(elfRelType + ".init_array")
}
if !*FlagS {
shstrtab.Addstring(".symtab")
shstrtab.Addstring(".strtab")
dwarfaddshstrings(ctxt, shstrtab)
}
shstrtab.Addstring(".shstrtab")
if !*FlagD { /* -d suppresses dynamic loader format */
shstrtab.Addstring(".interp")
shstrtab.Addstring(".hash")
shstrtab.Addstring(".got")
if ctxt.IsPPC64() {
shstrtab.Addstring(".glink")
}
shstrtab.Addstring(".got.plt")
shstrtab.Addstring(".dynamic")
shstrtab.Addstring(".dynsym")
shstrtab.Addstring(".dynstr")
shstrtab.Addstring(elfRelType)
shstrtab.Addstring(elfRelType + ".plt")
shstrtab.Addstring(".plt")
shstrtab.Addstring(".gnu.version")
shstrtab.Addstring(".gnu.version_r")
/* dynamic symbol table - first entry all zeros */
dynsym := ldr.CreateSymForUpdate(".dynsym", 0)
dynsym.SetType(sym.SELFROSECT)
if elf64 {
dynsym.SetSize(dynsym.Size() + ELF64SYMSIZE)
} else {
dynsym.SetSize(dynsym.Size() + ELF32SYMSIZE)
}
/* dynamic string table */
dynstr := ldr.CreateSymForUpdate(".dynstr", 0)
dynstr.SetType(sym.SELFROSECT)
if dynstr.Size() == 0 {
dynstr.Addstring("")
}
/* relocation table */
s := ldr.CreateSymForUpdate(elfRelType, 0)
s.SetType(sym.SELFROSECT)
/* global offset table */
got := ldr.CreateSymForUpdate(".got", 0)
got.SetType(sym.SELFGOT) // writable
/* ppc64 glink resolver */
if ctxt.IsPPC64() {
s := ldr.CreateSymForUpdate(".glink", 0)
s.SetType(sym.SELFRXSECT)
}
/* hash */
hash := ldr.CreateSymForUpdate(".hash", 0)
hash.SetType(sym.SELFROSECT)
gotplt := ldr.CreateSymForUpdate(".got.plt", 0)
gotplt.SetType(sym.SELFSECT) // writable
plt := ldr.CreateSymForUpdate(".plt", 0)
if ctxt.IsPPC64() {
// In the ppc64 ABI, .plt is a data section
// written by the dynamic linker.
plt.SetType(sym.SELFSECT)
} else {
plt.SetType(sym.SELFRXSECT)
}
s = ldr.CreateSymForUpdate(elfRelType+".plt", 0)
s.SetType(sym.SELFROSECT)
s = ldr.CreateSymForUpdate(".gnu.version", 0)
s.SetType(sym.SELFROSECT)
s = ldr.CreateSymForUpdate(".gnu.version_r", 0)
s.SetType(sym.SELFROSECT)
/* define dynamic elf table */
dynamic := ldr.CreateSymForUpdate(".dynamic", 0)
if thearch.ELF.DynamicReadOnly {
dynamic.SetType(sym.SELFROSECT)
} else {
dynamic.SetType(sym.SELFSECT)
}
if ctxt.IsS390X() {
// S390X uses .got instead of .got.plt
gotplt = got
}
thearch.ELF.SetupPLT(ctxt, plt, gotplt, dynamic.Sym())
/*
* .dynamic table
*/
elfWriteDynEntSym(ctxt, dynamic, elf.DT_HASH, hash.Sym())
elfWriteDynEntSym(ctxt, dynamic, elf.DT_SYMTAB, dynsym.Sym())
if elf64 {
Elfwritedynent(ctxt.Arch, dynamic, elf.DT_SYMENT, ELF64SYMSIZE)
} else {
Elfwritedynent(ctxt.Arch, dynamic, elf.DT_SYMENT, ELF32SYMSIZE)
}
elfWriteDynEntSym(ctxt, dynamic, elf.DT_STRTAB, dynstr.Sym())
elfwritedynentsymsize(ctxt, dynamic, elf.DT_STRSZ, dynstr.Sym())
if elfRelType == ".rela" {
rela := ldr.LookupOrCreateSym(".rela", 0)
elfWriteDynEntSym(ctxt, dynamic, elf.DT_RELA, rela)
elfwritedynentsymsize(ctxt, dynamic, elf.DT_RELASZ, rela)
Elfwritedynent(ctxt.Arch, dynamic, elf.DT_RELAENT, ELF64RELASIZE)
} else {
rel := ldr.LookupOrCreateSym(".rel", 0)
elfWriteDynEntSym(ctxt, dynamic, elf.DT_REL, rel)
elfwritedynentsymsize(ctxt, dynamic, elf.DT_RELSZ, rel)
Elfwritedynent(ctxt.Arch, dynamic, elf.DT_RELENT, ELF32RELSIZE)
}
if rpath.val != "" {
Elfwritedynent(ctxt.Arch, dynamic, elf.DT_RUNPATH, uint64(dynstr.Addstring(rpath.val)))
}
if ctxt.IsPPC64() {
elfWriteDynEntSym(ctxt, dynamic, elf.DT_PLTGOT, plt.Sym())
} else {
elfWriteDynEntSym(ctxt, dynamic, elf.DT_PLTGOT, gotplt.Sym())
}
if ctxt.IsPPC64() {
Elfwritedynent(ctxt.Arch, dynamic, elf.DT_PPC64_OPT, 0)
}
// Solaris dynamic linker can't handle an empty .rela.plt if
// DT_JMPREL is emitted so we have to defer generation of elf.DT_PLTREL,
// DT_PLTRELSZ, and elf.DT_JMPREL dynamic entries until after we know the
// size of .rel(a).plt section.
Elfwritedynent(ctxt.Arch, dynamic, elf.DT_DEBUG, 0)
}
if ctxt.IsShared() {
// The go.link.abihashbytes symbol will be pointed at the appropriate
// part of the .note.go.abihash section in data.go:func address().
s := ldr.LookupOrCreateSym("go:link.abihashbytes", 0)
sb := ldr.MakeSymbolUpdater(s)
ldr.SetAttrLocal(s, true)
sb.SetType(sym.SRODATA)
ldr.SetAttrSpecial(s, true)
sb.SetReachable(true)
sb.SetSize(notsha256.Size)
sort.Sort(byPkg(ctxt.Library))
h := notsha256.New()
for _, l := range ctxt.Library {
h.Write(l.Fingerprint[:])
}
addgonote(ctxt, ".note.go.abihash", ELF_NOTE_GOABIHASH_TAG, h.Sum([]byte{}))
addgonote(ctxt, ".note.go.pkg-list", ELF_NOTE_GOPKGLIST_TAG, pkglistfornote)
var deplist []string
for _, shlib := range ctxt.Shlibs {
deplist = append(deplist, filepath.Base(shlib.Path))
}
addgonote(ctxt, ".note.go.deps", ELF_NOTE_GODEPS_TAG, []byte(strings.Join(deplist, "\n")))
}
if ctxt.LinkMode == LinkExternal && *flagBuildid != "" {
addgonote(ctxt, ".note.go.buildid", ELF_NOTE_GOBUILDID_TAG, []byte(*flagBuildid))
}
//type mipsGnuAttributes struct {
// version uint8 // 'A'
// length uint32 // 15 including itself
// gnu [4]byte // "gnu\0"
// tag uint8 // 1:file, 2: section, 3: symbol, 1 here
// taglen uint32 // tag length, including tag, 7 here
// tagfp uint8 // 4
// fpAbi uint8 // see .MIPS.abiflags
//}
if ctxt.IsMIPS() {
gnuattributes := ldr.CreateSymForUpdate(".gnu.attributes", 0)
gnuattributes.SetType(sym.SELFROSECT)
gnuattributes.SetReachable(true)
gnuattributes.AddUint8('A') // version 'A'
gnuattributes.AddUint32(ctxt.Arch, 15) // length 15 including itself
gnuattributes.AddBytes([]byte("gnu\x00")) // "gnu\0"
gnuattributes.AddUint8(1) // 1:file, 2: section, 3: symbol, 1 here
gnuattributes.AddUint32(ctxt.Arch, 7) // tag length, including tag, 7 here
gnuattributes.AddUint8(4) // 4 for FP, 8 for MSA
if buildcfg.GOMIPS == "softfloat" {
gnuattributes.AddUint8(MIPS_FPABI_SOFT)
} else {
// Note: MIPS_FPABI_ANY is bad naming: in fact it is MIPS I style FPR usage.
// It is not for 'ANY'.
// TODO: switch to FPXX after be sure that no odd-number-fpr is used.
gnuattributes.AddUint8(MIPS_FPABI_ANY)
}
}
}
// Do not write DT_NULL. elfdynhash will finish it.
func shsym(sh *ElfShdr, ldr *loader.Loader, s loader.Sym) {
if s == 0 {
panic("bad symbol in shsym2")
}
addr := ldr.SymValue(s)
if sh.Flags&uint64(elf.SHF_ALLOC) != 0 {
sh.Addr = uint64(addr)
}
sh.Off = uint64(datoff(ldr, s, addr))
sh.Size = uint64(ldr.SymSize(s))
}
func phsh(ph *ElfPhdr, sh *ElfShdr) {
ph.Vaddr = sh.Addr
ph.Paddr = ph.Vaddr
ph.Off = sh.Off
ph.Filesz = sh.Size
ph.Memsz = sh.Size
ph.Align = sh.Addralign
}
func Asmbelfsetup() {
/* This null SHdr must appear before all others */
elfshname("")
for _, sect := range Segtext.Sections {
// There could be multiple .text sections. Instead check the Elfsect
// field to determine if already has an ElfShdr and if not, create one.
if sect.Name == ".text" {
if sect.Elfsect == nil {
sect.Elfsect = elfshnamedup(sect.Name)
}
} else {
elfshalloc(sect)
}
}
for _, sect := range Segrodata.Sections {
elfshalloc(sect)
}
for _, sect := range Segrelrodata.Sections {
elfshalloc(sect)
}
for _, sect := range Segdata.Sections {
elfshalloc(sect)
}
for _, sect := range Segdwarf.Sections {
elfshalloc(sect)
}
}
func asmbElf(ctxt *Link) {
var symo int64
if !*FlagS {
symo = int64(Segdwarf.Fileoff + Segdwarf.Filelen)
symo = Rnd(symo, int64(ctxt.Arch.PtrSize))
ctxt.Out.SeekSet(symo)
asmElfSym(ctxt)
ctxt.Out.Write(Elfstrdat)
if ctxt.IsExternal() {
elfEmitReloc(ctxt)
}
}
ctxt.Out.SeekSet(0)
ldr := ctxt.loader
eh := getElfEhdr()
switch ctxt.Arch.Family {
default:
Exitf("unknown architecture in asmbelf: %v", ctxt.Arch.Family)
case sys.MIPS, sys.MIPS64:
eh.Machine = uint16(elf.EM_MIPS)
case sys.Loong64:
eh.Machine = uint16(elf.EM_LOONGARCH)
case sys.ARM:
eh.Machine = uint16(elf.EM_ARM)
case sys.AMD64:
eh.Machine = uint16(elf.EM_X86_64)
case sys.ARM64:
eh.Machine = uint16(elf.EM_AARCH64)
case sys.I386:
eh.Machine = uint16(elf.EM_386)
case sys.PPC64:
eh.Machine = uint16(elf.EM_PPC64)
case sys.RISCV64:
eh.Machine = uint16(elf.EM_RISCV)
case sys.S390X:
eh.Machine = uint16(elf.EM_S390)
}
elfreserve := int64(ELFRESERVE)
numtext := int64(0)
for _, sect := range Segtext.Sections {
if sect.Name == ".text" {
numtext++
}
}
// If there are multiple text sections, extra space is needed
// in the elfreserve for the additional .text and .rela.text
// section headers. It can handle 4 extra now. Headers are
// 64 bytes.
if numtext > 4 {
elfreserve += elfreserve + numtext*64*2
}
startva := *FlagTextAddr - int64(HEADR)
resoff := elfreserve
var pph *ElfPhdr
var pnote *ElfPhdr
getpnote := func() *ElfPhdr {
if pnote == nil {
pnote = newElfPhdr()
pnote.Type = elf.PT_NOTE
pnote.Flags = elf.PF_R
}
return pnote
}
if *flagRace && ctxt.IsNetbsd() {
sh := elfshname(".note.netbsd.pax")
resoff -= int64(elfnetbsdpax(sh, uint64(startva), uint64(resoff)))
phsh(getpnote(), sh)
}
if ctxt.LinkMode == LinkExternal {
/* skip program headers */
eh.Phoff = 0
eh.Phentsize = 0
if ctxt.BuildMode == BuildModeShared {
sh := elfshname(".note.go.pkg-list")
sh.Type = uint32(elf.SHT_NOTE)
sh = elfshname(".note.go.abihash")
sh.Type = uint32(elf.SHT_NOTE)
sh.Flags = uint64(elf.SHF_ALLOC)
sh = elfshname(".note.go.deps")
sh.Type = uint32(elf.SHT_NOTE)
}
if *flagBuildid != "" {
sh := elfshname(".note.go.buildid")
sh.Type = uint32(elf.SHT_NOTE)
sh.Flags = uint64(elf.SHF_ALLOC)
}
goto elfobj
}
/* program header info */
pph = newElfPhdr()
pph.Type = elf.PT_PHDR
pph.Flags = elf.PF_R
pph.Off = uint64(eh.Ehsize)
pph.Vaddr = uint64(*FlagTextAddr) - uint64(HEADR) + pph.Off
pph.Paddr = uint64(*FlagTextAddr) - uint64(HEADR) + pph.Off
pph.Align = uint64(*FlagRound)
/*
* PHDR must be in a loaded segment. Adjust the text
* segment boundaries downwards to include it.
*/
{
o := int64(Segtext.Vaddr - pph.Vaddr)
Segtext.Vaddr -= uint64(o)
Segtext.Length += uint64(o)
o = int64(Segtext.Fileoff - pph.Off)
Segtext.Fileoff -= uint64(o)
Segtext.Filelen += uint64(o)
}
if !*FlagD { /* -d suppresses dynamic loader format */
/* interpreter */
sh := elfshname(".interp")
sh.Type = uint32(elf.SHT_PROGBITS)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Addralign = 1
if interpreter == "" && buildcfg.GOOS == runtime.GOOS && buildcfg.GOARCH == runtime.GOARCH && buildcfg.GO_LDSO != "" {
interpreter = buildcfg.GO_LDSO
}
if interpreter == "" {
switch ctxt.HeadType {
case objabi.Hlinux:
if buildcfg.GOOS == "android" {
interpreter = thearch.ELF.Androiddynld
if interpreter == "" {
Exitf("ELF interpreter not set")
}
} else {
interpreter = thearch.ELF.Linuxdynld
// If interpreter does not exist, try musl instead.
// This lets the same cmd/link binary work on
// both glibc-based and musl-based systems.
if _, err := os.Stat(interpreter); err != nil {
if musl := thearch.ELF.LinuxdynldMusl; musl != "" {
if _, err := os.Stat(musl); err == nil {
interpreter = musl
}
}
}
}
case objabi.Hfreebsd:
interpreter = thearch.ELF.Freebsddynld
case objabi.Hnetbsd:
interpreter = thearch.ELF.Netbsddynld
case objabi.Hopenbsd:
interpreter = thearch.ELF.Openbsddynld
case objabi.Hdragonfly:
interpreter = thearch.ELF.Dragonflydynld
case objabi.Hsolaris:
interpreter = thearch.ELF.Solarisdynld
}
}
resoff -= int64(elfinterp(sh, uint64(startva), uint64(resoff), interpreter))
ph := newElfPhdr()
ph.Type = elf.PT_INTERP
ph.Flags = elf.PF_R
phsh(ph, sh)
}
if ctxt.HeadType == objabi.Hnetbsd || ctxt.HeadType == objabi.Hopenbsd || ctxt.HeadType == objabi.Hfreebsd {
var sh *ElfShdr
switch ctxt.HeadType {
case objabi.Hnetbsd:
sh = elfshname(".note.netbsd.ident")
resoff -= int64(elfnetbsdsig(sh, uint64(startva), uint64(resoff)))
case objabi.Hopenbsd:
sh = elfshname(".note.openbsd.ident")
resoff -= int64(elfopenbsdsig(sh, uint64(startva), uint64(resoff)))
case objabi.Hfreebsd:
sh = elfshname(".note.tag")
resoff -= int64(elffreebsdsig(sh, uint64(startva), uint64(resoff)))
}
// NetBSD, OpenBSD and FreeBSD require ident in an independent segment.
pnotei := newElfPhdr()
pnotei.Type = elf.PT_NOTE
pnotei.Flags = elf.PF_R
phsh(pnotei, sh)
}
if len(buildinfo) > 0 {
sh := elfshname(".note.gnu.build-id")
resoff -= int64(elfbuildinfo(sh, uint64(startva), uint64(resoff)))
phsh(getpnote(), sh)
}
if *flagBuildid != "" {
sh := elfshname(".note.go.buildid")
resoff -= int64(elfgobuildid(sh, uint64(startva), uint64(resoff)))
phsh(getpnote(), sh)
}
// Additions to the reserved area must be above this line.
elfphload(&Segtext)
if len(Segrodata.Sections) > 0 {
elfphload(&Segrodata)
}
if len(Segrelrodata.Sections) > 0 {
elfphload(&Segrelrodata)
elfphrelro(&Segrelrodata)
}
elfphload(&Segdata)
/* Dynamic linking sections */
if !*FlagD {
sh := elfshname(".dynsym")
sh.Type = uint32(elf.SHT_DYNSYM)
sh.Flags = uint64(elf.SHF_ALLOC)
if elf64 {
sh.Entsize = ELF64SYMSIZE
} else {
sh.Entsize = ELF32SYMSIZE
}
sh.Addralign = uint64(ctxt.Arch.RegSize)
sh.Link = uint32(elfshname(".dynstr").shnum)
// sh.info is the index of first non-local symbol (number of local symbols)
s := ldr.Lookup(".dynsym", 0)
i := uint32(0)
for sub := s; sub != 0; sub = ldr.SubSym(sub) {
i++
if !ldr.AttrLocal(sub) {
break
}
}
sh.Info = i
shsym(sh, ldr, s)
sh = elfshname(".dynstr")
sh.Type = uint32(elf.SHT_STRTAB)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Addralign = 1
shsym(sh, ldr, ldr.Lookup(".dynstr", 0))
if elfverneed != 0 {
sh := elfshname(".gnu.version")
sh.Type = uint32(elf.SHT_GNU_VERSYM)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Addralign = 2
sh.Link = uint32(elfshname(".dynsym").shnum)
sh.Entsize = 2
shsym(sh, ldr, ldr.Lookup(".gnu.version", 0))
sh = elfshname(".gnu.version_r")
sh.Type = uint32(elf.SHT_GNU_VERNEED)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Addralign = uint64(ctxt.Arch.RegSize)
sh.Info = uint32(elfverneed)
sh.Link = uint32(elfshname(".dynstr").shnum)
shsym(sh, ldr, ldr.Lookup(".gnu.version_r", 0))
}
if elfRelType == ".rela" {
sh := elfshname(".rela.plt")
sh.Type = uint32(elf.SHT_RELA)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Entsize = ELF64RELASIZE
sh.Addralign = uint64(ctxt.Arch.RegSize)
sh.Link = uint32(elfshname(".dynsym").shnum)
sh.Info = uint32(elfshname(".plt").shnum)
shsym(sh, ldr, ldr.Lookup(".rela.plt", 0))
sh = elfshname(".rela")
sh.Type = uint32(elf.SHT_RELA)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Entsize = ELF64RELASIZE
sh.Addralign = 8
sh.Link = uint32(elfshname(".dynsym").shnum)
shsym(sh, ldr, ldr.Lookup(".rela", 0))
} else {
sh := elfshname(".rel.plt")
sh.Type = uint32(elf.SHT_REL)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Entsize = ELF32RELSIZE
sh.Addralign = 4
sh.Link = uint32(elfshname(".dynsym").shnum)
shsym(sh, ldr, ldr.Lookup(".rel.plt", 0))
sh = elfshname(".rel")
sh.Type = uint32(elf.SHT_REL)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Entsize = ELF32RELSIZE
sh.Addralign = 4
sh.Link = uint32(elfshname(".dynsym").shnum)
shsym(sh, ldr, ldr.Lookup(".rel", 0))
}
if elf.Machine(eh.Machine) == elf.EM_PPC64 {
sh := elfshname(".glink")
sh.Type = uint32(elf.SHT_PROGBITS)
sh.Flags = uint64(elf.SHF_ALLOC + elf.SHF_EXECINSTR)
sh.Addralign = 4
shsym(sh, ldr, ldr.Lookup(".glink", 0))
}
sh = elfshname(".plt")
sh.Type = uint32(elf.SHT_PROGBITS)
sh.Flags = uint64(elf.SHF_ALLOC + elf.SHF_EXECINSTR)
if elf.Machine(eh.Machine) == elf.EM_X86_64 {
sh.Entsize = 16
} else if elf.Machine(eh.Machine) == elf.EM_S390 {
sh.Entsize = 32
} else if elf.Machine(eh.Machine) == elf.EM_PPC64 {
// On ppc64, this is just a table of addresses
// filled by the dynamic linker
sh.Type = uint32(elf.SHT_NOBITS)
sh.Flags = uint64(elf.SHF_ALLOC + elf.SHF_WRITE)
sh.Entsize = 8
} else {
sh.Entsize = 4
}
sh.Addralign = sh.Entsize
shsym(sh, ldr, ldr.Lookup(".plt", 0))
// On ppc64, .got comes from the input files, so don't
// create it here, and .got.plt is not used.
if elf.Machine(eh.Machine) != elf.EM_PPC64 {
sh := elfshname(".got")
sh.Type = uint32(elf.SHT_PROGBITS)
sh.Flags = uint64(elf.SHF_ALLOC + elf.SHF_WRITE)
sh.Entsize = uint64(ctxt.Arch.RegSize)
sh.Addralign = uint64(ctxt.Arch.RegSize)
shsym(sh, ldr, ldr.Lookup(".got", 0))
sh = elfshname(".got.plt")
sh.Type = uint32(elf.SHT_PROGBITS)
sh.Flags = uint64(elf.SHF_ALLOC + elf.SHF_WRITE)
sh.Entsize = uint64(ctxt.Arch.RegSize)
sh.Addralign = uint64(ctxt.Arch.RegSize)
shsym(sh, ldr, ldr.Lookup(".got.plt", 0))
}
sh = elfshname(".hash")
sh.Type = uint32(elf.SHT_HASH)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Entsize = 4
sh.Addralign = uint64(ctxt.Arch.RegSize)
sh.Link = uint32(elfshname(".dynsym").shnum)
shsym(sh, ldr, ldr.Lookup(".hash", 0))
/* sh and elf.PT_DYNAMIC for .dynamic section */
sh = elfshname(".dynamic")
sh.Type = uint32(elf.SHT_DYNAMIC)
sh.Flags = uint64(elf.SHF_ALLOC + elf.SHF_WRITE)
sh.Entsize = 2 * uint64(ctxt.Arch.RegSize)
sh.Addralign = uint64(ctxt.Arch.RegSize)
sh.Link = uint32(elfshname(".dynstr").shnum)
shsym(sh, ldr, ldr.Lookup(".dynamic", 0))
ph := newElfPhdr()
ph.Type = elf.PT_DYNAMIC
ph.Flags = elf.PF_R + elf.PF_W
phsh(ph, sh)
/*
* Thread-local storage segment (really just size).
*/
tlssize := uint64(0)
for _, sect := range Segdata.Sections {
if sect.Name == ".tbss" {
tlssize = sect.Length
}
}
if tlssize != 0 {
ph := newElfPhdr()
ph.Type = elf.PT_TLS
ph.Flags = elf.PF_R
ph.Memsz = tlssize
ph.Align = uint64(ctxt.Arch.RegSize)
}
}
if ctxt.HeadType == objabi.Hlinux || ctxt.HeadType == objabi.Hfreebsd {
ph := newElfPhdr()
ph.Type = elf.PT_GNU_STACK
ph.Flags = elf.PF_W + elf.PF_R
ph.Align = uint64(ctxt.Arch.RegSize)
} else if ctxt.HeadType == objabi.Hsolaris {
ph := newElfPhdr()
ph.Type = elf.PT_SUNWSTACK
ph.Flags = elf.PF_W + elf.PF_R
}
elfobj:
sh := elfshname(".shstrtab")
sh.Type = uint32(elf.SHT_STRTAB)
sh.Addralign = 1
shsym(sh, ldr, ldr.Lookup(".shstrtab", 0))
eh.Shstrndx = uint16(sh.shnum)
if ctxt.IsMIPS() {
sh = elfshname(".MIPS.abiflags")
sh.Type = uint32(elf.SHT_MIPS_ABIFLAGS)
sh.Flags = uint64(elf.SHF_ALLOC)
sh.Addralign = 8
resoff -= int64(elfMipsAbiFlags(sh, uint64(startva), uint64(resoff)))
ph := newElfPhdr()
ph.Type = elf.PT_MIPS_ABIFLAGS
ph.Flags = elf.PF_R
phsh(ph, sh)
sh = elfshname(".gnu.attributes")
sh.Type = uint32(elf.SHT_GNU_ATTRIBUTES)
sh.Addralign = 1
ldr := ctxt.loader
shsym(sh, ldr, ldr.Lookup(".gnu.attributes", 0))
}
// put these sections early in the list
if !*FlagS {
elfshname(".symtab")
elfshname(".strtab")
}
for _, sect := range Segtext.Sections {
elfshbits(ctxt.LinkMode, sect)
}
for _, sect := range Segrodata.Sections {
elfshbits(ctxt.LinkMode, sect)
}
for _, sect := range Segrelrodata.Sections {
elfshbits(ctxt.LinkMode, sect)
}
for _, sect := range Segdata.Sections {
elfshbits(ctxt.LinkMode, sect)
}
for _, sect := range Segdwarf.Sections {
elfshbits(ctxt.LinkMode, sect)
}
if ctxt.LinkMode == LinkExternal {
for _, sect := range Segtext.Sections {
elfshreloc(ctxt.Arch, sect)
}
for _, sect := range Segrodata.Sections {
elfshreloc(ctxt.Arch, sect)
}
for _, sect := range Segrelrodata.Sections {
elfshreloc(ctxt.Arch, sect)
}
for _, sect := range Segdata.Sections {
elfshreloc(ctxt.Arch, sect)
}
for _, si := range dwarfp {
sect := ldr.SymSect(si.secSym())
elfshreloc(ctxt.Arch, sect)
}
// add a .note.GNU-stack section to mark the stack as non-executable
sh := elfshname(".note.GNU-stack")
sh.Type = uint32(elf.SHT_PROGBITS)
sh.Addralign = 1
sh.Flags = 0
}
if !*FlagS {
sh := elfshname(".symtab")
sh.Type = uint32(elf.SHT_SYMTAB)
sh.Off = uint64(symo)
sh.Size = uint64(symSize)
sh.Addralign = uint64(ctxt.Arch.RegSize)
sh.Entsize = 8 + 2*uint64(ctxt.Arch.RegSize)
sh.Link = uint32(elfshname(".strtab").shnum)
sh.Info = uint32(elfglobalsymndx)
sh = elfshname(".strtab")
sh.Type = uint32(elf.SHT_STRTAB)
sh.Off = uint64(symo) + uint64(symSize)
sh.Size = uint64(len(Elfstrdat))
sh.Addralign = 1
}
/* Main header */
copy(eh.Ident[:], elf.ELFMAG)
var osabi elf.OSABI
switch ctxt.HeadType {
case objabi.Hfreebsd:
osabi = elf.ELFOSABI_FREEBSD
case objabi.Hnetbsd:
osabi = elf.ELFOSABI_NETBSD
case objabi.Hopenbsd:
osabi = elf.ELFOSABI_OPENBSD
case objabi.Hdragonfly:
osabi = elf.ELFOSABI_NONE
}
eh.Ident[elf.EI_OSABI] = byte(osabi)
if elf64 {
eh.Ident[elf.EI_CLASS] = byte(elf.ELFCLASS64)
} else {
eh.Ident[elf.EI_CLASS] = byte(elf.ELFCLASS32)
}
if ctxt.Arch.ByteOrder == binary.BigEndian {
eh.Ident[elf.EI_DATA] = byte(elf.ELFDATA2MSB)
} else {
eh.Ident[elf.EI_DATA] = byte(elf.ELFDATA2LSB)
}
eh.Ident[elf.EI_VERSION] = byte(elf.EV_CURRENT)
if ctxt.LinkMode == LinkExternal {
eh.Type = uint16(elf.ET_REL)
} else if ctxt.BuildMode == BuildModePIE {
eh.Type = uint16(elf.ET_DYN)
} else {
eh.Type = uint16(elf.ET_EXEC)
}
if ctxt.LinkMode != LinkExternal {
eh.Entry = uint64(Entryvalue(ctxt))
}
eh.Version = uint32(elf.EV_CURRENT)
if pph != nil {
pph.Filesz = uint64(eh.Phnum) * uint64(eh.Phentsize)
pph.Memsz = pph.Filesz
}
ctxt.Out.SeekSet(0)
a := int64(0)
a += int64(elfwritehdr(ctxt.Out))
a += int64(elfwritephdrs(ctxt.Out))
a += int64(elfwriteshdrs(ctxt.Out))
if !*FlagD {
a += int64(elfwriteinterp(ctxt.Out))
}
if ctxt.IsMIPS() {
a += int64(elfWriteMipsAbiFlags(ctxt))
}
if ctxt.LinkMode != LinkExternal {
if ctxt.HeadType == objabi.Hnetbsd {
a += int64(elfwritenetbsdsig(ctxt.Out))
}
if ctxt.HeadType == objabi.Hopenbsd {
a += int64(elfwriteopenbsdsig(ctxt.Out))
}
if ctxt.HeadType == objabi.Hfreebsd {
a += int64(elfwritefreebsdsig(ctxt.Out))
}
if len(buildinfo) > 0 {
a += int64(elfwritebuildinfo(ctxt.Out))
}
if *flagBuildid != "" {
a += int64(elfwritegobuildid(ctxt.Out))
}
}
if *flagRace && ctxt.IsNetbsd() {
a += int64(elfwritenetbsdpax(ctxt.Out))
}
if a > elfreserve {
Errorf(nil, "ELFRESERVE too small: %d > %d with %d text sections", a, elfreserve, numtext)
}
// Verify the amount of space allocated for the elf header is sufficient. The file offsets are
// already computed in layout, so we could spill into another section.
if a > int64(HEADR) {
Errorf(nil, "HEADR too small: %d > %d with %d text sections", a, HEADR, numtext)
}
}
func elfadddynsym(ldr *loader.Loader, target *Target, syms *ArchSyms, s loader.Sym) {
ldr.SetSymDynid(s, int32(Nelfsym))
Nelfsym++
d := ldr.MakeSymbolUpdater(syms.DynSym)
name := ldr.SymExtname(s)
dstru := ldr.MakeSymbolUpdater(syms.DynStr)
st := ldr.SymType(s)
cgoeStatic := ldr.AttrCgoExportStatic(s)
cgoeDynamic := ldr.AttrCgoExportDynamic(s)
cgoexp := (cgoeStatic || cgoeDynamic)
d.AddUint32(target.Arch, uint32(dstru.Addstring(name)))
if elf64 {
/* type */
var t uint8
if cgoexp && st == sym.STEXT {
t = elf.ST_INFO(elf.STB_GLOBAL, elf.STT_FUNC)
} else {
t = elf.ST_INFO(elf.STB_GLOBAL, elf.STT_OBJECT)
}
d.AddUint8(t)
/* reserved */
d.AddUint8(0)
/* section where symbol is defined */
if st == sym.SDYNIMPORT {
d.AddUint16(target.Arch, uint16(elf.SHN_UNDEF))
} else {
d.AddUint16(target.Arch, 1)
}
/* value */
if st == sym.SDYNIMPORT {
d.AddUint64(target.Arch, 0)
} else {
d.AddAddrPlus(target.Arch, s, 0)
}
/* size of object */
d.AddUint64(target.Arch, uint64(len(ldr.Data(s))))
dil := ldr.SymDynimplib(s)
if !cgoeDynamic && dil != "" && !seenlib[dil] {
du := ldr.MakeSymbolUpdater(syms.Dynamic)
Elfwritedynent(target.Arch, du, elf.DT_NEEDED, uint64(dstru.Addstring(dil)))
seenlib[dil] = true
}
} else {
/* value */
if st == sym.SDYNIMPORT {
d.AddUint32(target.Arch, 0)
} else {
d.AddAddrPlus(target.Arch, s, 0)
}
/* size of object */
d.AddUint32(target.Arch, uint32(len(ldr.Data(s))))
/* type */
var t uint8
// TODO(mwhudson): presumably the behavior should actually be the same on both arm and 386.
if target.Arch.Family == sys.I386 && cgoexp && st == sym.STEXT {
t = elf.ST_INFO(elf.STB_GLOBAL, elf.STT_FUNC)
} else if target.Arch.Family == sys.ARM && cgoeDynamic && st == sym.STEXT {
t = elf.ST_INFO(elf.STB_GLOBAL, elf.STT_FUNC)
} else {
t = elf.ST_INFO(elf.STB_GLOBAL, elf.STT_OBJECT)
}
d.AddUint8(t)
d.AddUint8(0)
/* shndx */
if st == sym.SDYNIMPORT {
d.AddUint16(target.Arch, uint16(elf.SHN_UNDEF))
} else {
d.AddUint16(target.Arch, 1)
}
}
}