// Inferno utils/5l/asm.c
// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/5l/asm.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 arm64
import (
"cmd/internal/objabi"
"cmd/internal/sys"
"cmd/link/internal/ld"
"cmd/link/internal/loader"
"cmd/link/internal/sym"
"debug/elf"
"fmt"
"log"
)
func gentext(ctxt *ld.Link, ldr *loader.Loader) {
initfunc, addmoduledata := ld.PrepareAddmoduledata(ctxt)
if initfunc == nil {
return
}
o := func(op uint32) {
initfunc.AddUint32(ctxt.Arch, op)
}
// 0000000000000000 <local.dso_init>:
// 0: 90000000 adrp x0, 0 <runtime.firstmoduledata>
// 0: R_AARCH64_ADR_PREL_PG_HI21 local.moduledata
// 4: 91000000 add x0, x0, #0x0
// 4: R_AARCH64_ADD_ABS_LO12_NC local.moduledata
o(0x90000000)
o(0x91000000)
rel, _ := initfunc.AddRel(objabi.R_ADDRARM64)
rel.SetOff(0)
rel.SetSiz(8)
rel.SetSym(ctxt.Moduledata)
// 8: 14000000 b 0 <runtime.addmoduledata>
// 8: R_AARCH64_CALL26 runtime.addmoduledata
o(0x14000000)
rel2, _ := initfunc.AddRel(objabi.R_CALLARM64)
rel2.SetOff(8)
rel2.SetSiz(4)
rel2.SetSym(addmoduledata)
}
func adddynrel(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym, r loader.Reloc, rIdx int) bool {
targ := r.Sym()
var targType sym.SymKind
if targ != 0 {
targType = ldr.SymType(targ)
}
const pcrel = 1
switch r.Type() {
default:
if r.Type() >= objabi.ElfRelocOffset {
ldr.Errorf(s, "unexpected relocation type %d (%s)", r.Type(), sym.RelocName(target.Arch, r.Type()))
return false
}
// Handle relocations found in ELF object files.
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_PREL32):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected R_AARCH64_PREL32 relocation for dynamic symbol %s", ldr.SymName(targ))
}
if targType == 0 || targType == sym.SXREF {
ldr.Errorf(s, "unknown symbol %s in pcrel", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_PCREL)
su.SetRelocAdd(rIdx, r.Add()+4)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_PREL64):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected R_AARCH64_PREL64 relocation for dynamic symbol %s", ldr.SymName(targ))
}
if targType == 0 || targType == sym.SXREF {
ldr.Errorf(s, "unknown symbol %s in pcrel", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_PCREL)
su.SetRelocAdd(rIdx, r.Add()+8)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_CALL26),
objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_JUMP26):
if targType == sym.SDYNIMPORT {
addpltsym(target, ldr, syms, targ)
su := ldr.MakeSymbolUpdater(s)
su.SetRelocSym(rIdx, syms.PLT)
su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymPlt(targ)))
}
if targType == 0 || targType == sym.SXREF {
ldr.Errorf(s, "unknown symbol %s in callarm64", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_CALLARM64)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_ADR_GOT_PAGE),
objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LD64_GOT_LO12_NC):
if targType != sym.SDYNIMPORT {
// have symbol
// TODO: turn LDR of GOT entry into ADR of symbol itself
}
// fall back to using GOT
// TODO: just needs relocation, no need to put in .dynsym
ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_AARCH64_GLOB_DAT))
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_GOT)
su.SetRelocSym(rIdx, syms.GOT)
su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ)))
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_ADR_PREL_PG_HI21),
objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_ADD_ABS_LO12_NC):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
}
if targType == 0 || targType == sym.SXREF {
ldr.Errorf(s, "unknown symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_PCREL)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_ABS64):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected R_AARCH64_ABS64 relocation for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ADDR)
if target.IsPIE() && target.IsInternal() {
// For internal linking PIE, this R_ADDR relocation cannot
// be resolved statically. We need to generate a dynamic
// relocation. Let the code below handle it.
break
}
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST8_ABS_LO12_NC):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_LDST8)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST16_ABS_LO12_NC):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_LDST16)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST32_ABS_LO12_NC):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_LDST32)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST64_ABS_LO12_NC):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_LDST64)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST128_ABS_LO12_NC):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_LDST128)
return true
// Handle relocations found in Mach-O object files.
case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_UNSIGNED*2:
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected reloc for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ADDR)
if target.IsPIE() && target.IsInternal() {
// For internal linking PIE, this R_ADDR relocation cannot
// be resolved statically. We need to generate a dynamic
// relocation. Let the code below handle it.
break
}
return true
case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_BRANCH26*2 + pcrel:
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_CALLARM64)
if targType == sym.SDYNIMPORT {
addpltsym(target, ldr, syms, targ)
su.SetRelocSym(rIdx, syms.PLT)
su.SetRelocAdd(rIdx, int64(ldr.SymPlt(targ)))
}
return true
case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_PAGE21*2 + pcrel,
objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_PAGEOFF12*2:
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_PCREL)
return true
case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGE21*2 + pcrel,
objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12*2:
if targType != sym.SDYNIMPORT {
// have symbol
// turn MOVD sym@GOT (adrp+ldr) into MOVD $sym (adrp+add)
data := ldr.Data(s)
off := r.Off()
if int(off+3) >= len(data) {
ldr.Errorf(s, "unexpected GOT_LOAD reloc for non-dynamic symbol %s", ldr.SymName(targ))
return false
}
o := target.Arch.ByteOrder.Uint32(data[off:])
su := ldr.MakeSymbolUpdater(s)
switch {
case (o>>24)&0x9f == 0x90: // adrp
// keep instruction unchanged, change relocation type below
case o>>24 == 0xf9: // ldr
// rewrite to add
o = (0x91 << 24) | (o & (1<<22 - 1))
su.MakeWritable()
su.SetUint32(target.Arch, int64(off), o)
default:
ldr.Errorf(s, "unexpected GOT_LOAD reloc for non-dynamic symbol %s", ldr.SymName(targ))
return false
}
su.SetRelocType(rIdx, objabi.R_ARM64_PCREL)
return true
}
ld.AddGotSym(target, ldr, syms, targ, 0)
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ARM64_GOT)
su.SetRelocSym(rIdx, syms.GOT)
su.SetRelocAdd(rIdx, int64(ldr.SymGot(targ)))
return true
}
// Reread the reloc to incorporate any changes in type above.
relocs := ldr.Relocs(s)
r = relocs.At(rIdx)
switch r.Type() {
case objabi.R_CALLARM64:
if targType != sym.SDYNIMPORT {
// nothing to do, the relocation will be laid out in reloc
return true
}
if target.IsExternal() {
// External linker will do this relocation.
return true
}
// Internal linking.
if r.Add() != 0 {
ldr.Errorf(s, "PLT call with non-zero addend (%v)", r.Add())
}
// Build a PLT entry and change the relocation target to that entry.
addpltsym(target, ldr, syms, targ)
su := ldr.MakeSymbolUpdater(s)
su.SetRelocSym(rIdx, syms.PLT)
su.SetRelocAdd(rIdx, int64(ldr.SymPlt(targ)))
return true
case objabi.R_ADDRARM64:
if targType == sym.SDYNIMPORT && ldr.SymType(s).IsText() && target.IsDarwin() {
// Loading the address of a dynamic symbol. Rewrite to use GOT.
// turn MOVD $sym (adrp+add) into MOVD sym@GOT (adrp+ldr)
if r.Add() != 0 {
ldr.Errorf(s, "unexpected nonzero addend for dynamic symbol %s", ldr.SymName(targ))
return false
}
su := ldr.MakeSymbolUpdater(s)
data := ldr.Data(s)
off := r.Off()
if int(off+8) > len(data) {
ldr.Errorf(s, "unexpected R_ADDRARM64 reloc for dynamic symbol %s", ldr.SymName(targ))
return false
}
o := target.Arch.ByteOrder.Uint32(data[off+4:])
if o>>24 == 0x91 { // add
// rewrite to ldr
o = (0xf9 << 24) | 1<<22 | (o & (1<<22 - 1))
su.MakeWritable()
su.SetUint32(target.Arch, int64(off+4), o)
if target.IsInternal() {
ld.AddGotSym(target, ldr, syms, targ, 0)
su.SetRelocSym(rIdx, syms.GOT)
su.SetRelocAdd(rIdx, int64(ldr.SymGot(targ)))
su.SetRelocType(rIdx, objabi.R_ARM64_PCREL_LDST64)
} else {
su.SetRelocType(rIdx, objabi.R_ARM64_GOTPCREL)
}
return true
}
ldr.Errorf(s, "unexpected R_ADDRARM64 reloc for dynamic symbol %s", ldr.SymName(targ))
}
case objabi.R_ADDR:
if ldr.SymType(s).IsText() && target.IsElf() {
// The code is asking for the address of an external
// function. We provide it with the address of the
// correspondent GOT symbol.
ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_AARCH64_GLOB_DAT))
su := ldr.MakeSymbolUpdater(s)
su.SetRelocSym(rIdx, syms.GOT)
su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ)))
return true
}
// Process dynamic relocations for the data sections.
if target.IsPIE() && target.IsInternal() {
// When internally linking, generate dynamic relocations
// for all typical R_ADDR relocations. The exception
// are those R_ADDR that are created as part of generating
// the dynamic relocations and must be resolved statically.
//
// There are three phases relevant to understanding this:
//
// dodata() // we are here
// address() // symbol address assignment
// reloc() // resolution of static R_ADDR relocs
//
// At this point symbol addresses have not been
// assigned yet (as the final size of the .rela section
// will affect the addresses), and so we cannot write
// the Elf64_Rela.r_offset now. Instead we delay it
// until after the 'address' phase of the linker is
// complete. We do this via Addaddrplus, which creates
// a new R_ADDR relocation which will be resolved in
// the 'reloc' phase.
//
// These synthetic static R_ADDR relocs must be skipped
// now, or else we will be caught in an infinite loop
// of generating synthetic relocs for our synthetic
// relocs.
//
// Furthermore, the rela sections contain dynamic
// relocations with R_ADDR relocations on
// Elf64_Rela.r_offset. This field should contain the
// symbol offset as determined by reloc(), not the
// final dynamically linked address as a dynamic
// relocation would provide.
switch ldr.SymName(s) {
case ".dynsym", ".rela", ".rela.plt", ".got.plt", ".dynamic":
return false
}
} else {
// Either internally linking a static executable,
// in which case we can resolve these relocations
// statically in the 'reloc' phase, or externally
// linking, in which case the relocation will be
// prepared in the 'reloc' phase and passed to the
// external linker in the 'asmb' phase.
if t := ldr.SymType(s); !t.IsDATA() && !t.IsRODATA() {
break
}
}
if target.IsElf() {
// Generate R_AARCH64_RELATIVE relocations for best
// efficiency in the dynamic linker.
//
// As noted above, symbol addresses have not been
// assigned yet, so we can't generate the final reloc
// entry yet. We ultimately want:
//
// r_offset = s + r.Off
// r_info = R_AARCH64_RELATIVE
// r_addend = targ + r.Add
//
// The dynamic linker will set *offset = base address +
// addend.
//
// AddAddrPlus is used for r_offset and r_addend to
// generate new R_ADDR relocations that will update
// these fields in the 'reloc' phase.
rela := ldr.MakeSymbolUpdater(syms.Rela)
rela.AddAddrPlus(target.Arch, s, int64(r.Off()))
if r.Siz() == 8 {
rela.AddUint64(target.Arch, elf.R_INFO(0, uint32(elf.R_AARCH64_RELATIVE)))
} else {
ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
}
rela.AddAddrPlus(target.Arch, targ, int64(r.Add()))
// Not mark r done here. So we still apply it statically,
// so in the file content we'll also have the right offset
// to the relocation target. So it can be examined statically
// (e.g. go version).
return true
}
if target.IsDarwin() {
// Mach-O relocations are a royal pain to lay out.
// They use a compact stateful bytecode representation.
// Here we record what are needed and encode them later.
ld.MachoAddRebase(s, int64(r.Off()))
// Not mark r done here. So we still apply it statically,
// so in the file content we'll also have the right offset
// to the relocation target. So it can be examined statically
// (e.g. go version).
return true
}
case objabi.R_ARM64_GOTPCREL:
if target.IsExternal() {
// External linker will do this relocation.
return true
}
if targType != sym.SDYNIMPORT {
ldr.Errorf(s, "R_ARM64_GOTPCREL target is not SDYNIMPORT symbol: %v", ldr.SymName(targ))
}
if r.Add() != 0 {
ldr.Errorf(s, "R_ARM64_GOTPCREL with non-zero addend (%v)", r.Add())
}
if target.IsElf() {
ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_AARCH64_GLOB_DAT))
} else {
ld.AddGotSym(target, ldr, syms, targ, 0)
}
// turn into two relocations, one for each instruction.
su := ldr.MakeSymbolUpdater(s)
r.SetType(objabi.R_ARM64_GOT)
r.SetSiz(4)
r.SetSym(syms.GOT)
r.SetAdd(int64(ldr.SymGot(targ)))
r2, _ := su.AddRel(objabi.R_ARM64_GOT)
r2.SetSiz(4)
r2.SetOff(r.Off() + 4)
r2.SetSym(syms.GOT)
r2.SetAdd(int64(ldr.SymGot(targ)))
return true
}
return false
}
func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, ri int, sectoff int64) bool {
out.Write64(uint64(sectoff))
elfsym := ld.ElfSymForReloc(ctxt, r.Xsym)
siz := r.Size
switch r.Type {
default:
return false
case objabi.R_ADDR, objabi.R_DWARFSECREF:
switch siz {
case 4:
out.Write64(uint64(elf.R_AARCH64_ABS32) | uint64(elfsym)<<32)
case 8:
out.Write64(uint64(elf.R_AARCH64_ABS64) | uint64(elfsym)<<32)
default:
return false
}
case objabi.R_ADDRARM64:
// two relocations: R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_ADD_ABS_LO12_NC
out.Write64(uint64(elf.R_AARCH64_ADR_PREL_PG_HI21) | uint64(elfsym)<<32)
out.Write64(uint64(r.Xadd))
out.Write64(uint64(sectoff + 4))
out.Write64(uint64(elf.R_AARCH64_ADD_ABS_LO12_NC) | uint64(elfsym)<<32)
case objabi.R_ARM64_PCREL_LDST8,
objabi.R_ARM64_PCREL_LDST16,
objabi.R_ARM64_PCREL_LDST32,
objabi.R_ARM64_PCREL_LDST64:
// two relocations: R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_LDST{64/32/16/8}_ABS_LO12_NC
out.Write64(uint64(elf.R_AARCH64_ADR_PREL_PG_HI21) | uint64(elfsym)<<32)
out.Write64(uint64(r.Xadd))
out.Write64(uint64(sectoff + 4))
var ldstType elf.R_AARCH64
switch r.Type {
case objabi.R_ARM64_PCREL_LDST8:
ldstType = elf.R_AARCH64_LDST8_ABS_LO12_NC
case objabi.R_ARM64_PCREL_LDST16:
ldstType = elf.R_AARCH64_LDST16_ABS_LO12_NC
case objabi.R_ARM64_PCREL_LDST32:
ldstType = elf.R_AARCH64_LDST32_ABS_LO12_NC
case objabi.R_ARM64_PCREL_LDST64:
ldstType = elf.R_AARCH64_LDST64_ABS_LO12_NC
}
out.Write64(uint64(ldstType) | uint64(elfsym)<<32)
case objabi.R_ARM64_TLS_LE:
out.Write64(uint64(elf.R_AARCH64_TLSLE_MOVW_TPREL_G0) | uint64(elfsym)<<32)
case objabi.R_ARM64_TLS_IE:
out.Write64(uint64(elf.R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21) | uint64(elfsym)<<32)
out.Write64(uint64(r.Xadd))
out.Write64(uint64(sectoff + 4))
out.Write64(uint64(elf.R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC) | uint64(elfsym)<<32)
case objabi.R_ARM64_GOTPCREL:
out.Write64(uint64(elf.R_AARCH64_ADR_GOT_PAGE) | uint64(elfsym)<<32)
out.Write64(uint64(r.Xadd))
out.Write64(uint64(sectoff + 4))
out.Write64(uint64(elf.R_AARCH64_LD64_GOT_LO12_NC) | uint64(elfsym)<<32)
case objabi.R_CALLARM64:
if siz != 4 {
return false
}
out.Write64(uint64(elf.R_AARCH64_CALL26) | uint64(elfsym)<<32)
}
out.Write64(uint64(r.Xadd))
return true
}
// sign-extends from 21, 24-bit.
func signext21(x int64) int64 { return x << (64 - 21) >> (64 - 21) }
func signext24(x int64) int64 { return x << (64 - 24) >> (64 - 24) }
func machoreloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
var v uint32
rs := r.Xsym
rt := r.Type
siz := r.Size
xadd := r.Xadd
if xadd != signext24(xadd) && rt != objabi.R_ADDR {
// If the relocation target would overflow the addend, then target
// a linker-manufactured label symbol with a smaller addend instead.
// R_ADDR has full-width addend encoded in data content, so it doesn't
// use a label symbol.
label := ldr.Lookup(offsetLabelName(ldr, rs, xadd/machoRelocLimit*machoRelocLimit), ldr.SymVersion(rs))
if label != 0 {
xadd = ldr.SymValue(rs) + xadd - ldr.SymValue(label)
rs = label
}
if xadd != signext24(xadd) {
ldr.Errorf(s, "internal error: relocation addend overflow: %s+0x%x", ldr.SymName(rs), xadd)
}
}
if rt == objabi.R_CALLARM64 && xadd != 0 {
label := ldr.Lookup(offsetLabelName(ldr, rs, xadd), ldr.SymVersion(rs))
if label != 0 {
xadd = ldr.SymValue(rs) + xadd - ldr.SymValue(label) // should always be 0 (checked below)
rs = label
}
}
if !ldr.SymType(s).IsDWARF() {
if ldr.SymDynid(rs) < 0 {
ldr.Errorf(s, "reloc %d (%s) to non-macho symbol %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymType(rs), ldr.SymType(rs))
return false
}
v = uint32(ldr.SymDynid(rs))
v |= 1 << 27 // external relocation
} else {
v = uint32(ldr.SymSect(rs).Extnum)
if v == 0 {
ldr.Errorf(s, "reloc %d (%s) to symbol %s in non-macho section %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymSect(rs).Name, ldr.SymType(rs), ldr.SymType(rs))
return false
}
}
switch rt {
default:
return false
case objabi.R_ADDR:
v |= ld.MACHO_ARM64_RELOC_UNSIGNED << 28
case objabi.R_CALLARM64:
if xadd != 0 {
// Addend should be handled above via label symbols.
ldr.Errorf(s, "unexpected non-zero addend: %s+%d", ldr.SymName(rs), xadd)
}
v |= 1 << 24 // pc-relative bit
v |= ld.MACHO_ARM64_RELOC_BRANCH26 << 28
case objabi.R_ADDRARM64,
objabi.R_ARM64_PCREL_LDST8,
objabi.R_ARM64_PCREL_LDST16,
objabi.R_ARM64_PCREL_LDST32,
objabi.R_ARM64_PCREL_LDST64:
siz = 4
// Two relocation entries: MACHO_ARM64_RELOC_PAGEOFF12 MACHO_ARM64_RELOC_PAGE21
// if r.Xadd is non-zero, add two MACHO_ARM64_RELOC_ADDEND.
if r.Xadd != 0 {
out.Write32(uint32(sectoff + 4))
out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
}
out.Write32(uint32(sectoff + 4))
out.Write32(v | (ld.MACHO_ARM64_RELOC_PAGEOFF12 << 28) | (2 << 25))
if r.Xadd != 0 {
out.Write32(uint32(sectoff))
out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
}
v |= 1 << 24 // pc-relative bit
v |= ld.MACHO_ARM64_RELOC_PAGE21 << 28
case objabi.R_ARM64_GOTPCREL:
siz = 4
// Two relocation entries: MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12 MACHO_ARM64_RELOC_GOT_LOAD_PAGE21
// if r.Xadd is non-zero, add two MACHO_ARM64_RELOC_ADDEND.
if r.Xadd != 0 {
out.Write32(uint32(sectoff + 4))
out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
}
out.Write32(uint32(sectoff + 4))
out.Write32(v | (ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12 << 28) | (2 << 25))
if r.Xadd != 0 {
out.Write32(uint32(sectoff))
out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
}
v |= 1 << 24 // pc-relative bit
v |= ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGE21 << 28
}
switch siz {
default:
return false
case 1:
v |= 0 << 25
case 2:
v |= 1 << 25
case 4:
v |= 2 << 25
case 8:
v |= 3 << 25
}
out.Write32(uint32(sectoff))
out.Write32(v)
return true
}
func pereloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
rs := r.Xsym
rt := r.Type
if (rt == objabi.R_ADDRARM64 || rt == objabi.R_ARM64_PCREL_LDST8 || rt == objabi.R_ARM64_PCREL_LDST16 ||
rt == objabi.R_ARM64_PCREL_LDST32 || rt == objabi.R_ARM64_PCREL_LDST64) && r.Xadd != signext21(r.Xadd) {
// If the relocation target would overflow the addend, then target
// a linker-manufactured label symbol with a smaller addend instead.
label := ldr.Lookup(offsetLabelName(ldr, rs, r.Xadd/peRelocLimit*peRelocLimit), ldr.SymVersion(rs))
if label == 0 {
ldr.Errorf(s, "invalid relocation: %v %s+0x%x", rt, ldr.SymName(rs), r.Xadd)
return false
}
rs = label
}
if rt == objabi.R_CALLARM64 && r.Xadd != 0 {
label := ldr.Lookup(offsetLabelName(ldr, rs, r.Xadd), ldr.SymVersion(rs))
if label == 0 {
ldr.Errorf(s, "invalid relocation: %v %s+0x%x", rt, ldr.SymName(rs), r.Xadd)
return false
}
rs = label
}
symdynid := ldr.SymDynid(rs)
if symdynid < 0 {
ldr.Errorf(s, "reloc %d (%s) to non-coff symbol %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymType(rs), ldr.SymType(rs))
return false
}
switch rt {
default:
return false
case objabi.R_DWARFSECREF:
out.Write32(uint32(sectoff))
out.Write32(uint32(symdynid))
out.Write16(ld.IMAGE_REL_ARM64_SECREL)
case objabi.R_ADDR:
out.Write32(uint32(sectoff))
out.Write32(uint32(symdynid))
if r.Size == 8 {
out.Write16(ld.IMAGE_REL_ARM64_ADDR64)
} else {
out.Write16(ld.IMAGE_REL_ARM64_ADDR32)
}
case objabi.R_PEIMAGEOFF:
out.Write16(ld.IMAGE_REL_ARM64_ADDR32NB)
case objabi.R_ADDRARM64:
// Note: r.Xadd has been taken care of below, in archreloc.
out.Write32(uint32(sectoff))
out.Write32(uint32(symdynid))
out.Write16(ld.IMAGE_REL_ARM64_PAGEBASE_REL21)
out.Write32(uint32(sectoff + 4))
out.Write32(uint32(symdynid))
out.Write16(ld.IMAGE_REL_ARM64_PAGEOFFSET_12A)
case objabi.R_ARM64_PCREL_LDST8,
objabi.R_ARM64_PCREL_LDST16,
objabi.R_ARM64_PCREL_LDST32,
objabi.R_ARM64_PCREL_LDST64:
// Note: r.Xadd has been taken care of below, in archreloc.
out.Write32(uint32(sectoff))
out.Write32(uint32(symdynid))
out.Write16(ld.IMAGE_REL_ARM64_PAGEBASE_REL21)
out.Write32(uint32(sectoff + 4))
out.Write32(uint32(symdynid))
out.Write16(ld.IMAGE_REL_ARM64_PAGEOFFSET_12L)
case objabi.R_CALLARM64:
// Note: r.Xadd has been taken care of above, by using a label pointing into the middle of the function.
out.Write32(uint32(sectoff))
out.Write32(uint32(symdynid))
out.Write16(ld.IMAGE_REL_ARM64_BRANCH26)
}
return true
}
func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loader.Reloc, s loader.Sym, val int64) (int64, int, bool) {
const noExtReloc = 0
const isOk = true
rs := r.Sym()
if target.IsExternal() {
nExtReloc := 0
switch rt := r.Type(); rt {
default:
case objabi.R_ARM64_GOTPCREL,
objabi.R_ARM64_PCREL_LDST8,
objabi.R_ARM64_PCREL_LDST16,
objabi.R_ARM64_PCREL_LDST32,
objabi.R_ARM64_PCREL_LDST64,
objabi.R_ADDRARM64:
// set up addend for eventual relocation via outer symbol.
rs, off := ld.FoldSubSymbolOffset(ldr, rs)
xadd := r.Add() + off
rst := ldr.SymType(rs)
if rst != sym.SHOSTOBJ && rst != sym.SDYNIMPORT && ldr.SymSect(rs) == nil {
ldr.Errorf(s, "missing section for %s", ldr.SymName(rs))
}
nExtReloc = 2 // need two ELF/Mach-O relocations. see elfreloc1/machoreloc1
if target.IsDarwin() && xadd != 0 {
nExtReloc = 4 // need another two relocations for non-zero addend
}
if target.IsWindows() {
var o0, o1 uint32
if target.IsBigEndian() {
o0 = uint32(val >> 32)
o1 = uint32(val)
} else {
o0 = uint32(val)
o1 = uint32(val >> 32)
}
// The first instruction (ADRP) has a 21-bit immediate field,
// and the second (ADD or LD/ST) has a 12-bit immediate field.
// The first instruction is only for high bits, but to get the carry bits right we have
// to put the full addend, including the bottom 12 bits again.
// That limits the distance of any addend to only 21 bits.
// But we assume that ADRP's top bit will be interpreted as a sign bit,
// so we only use 20 bits.
// pereloc takes care of introducing new symbol labels
// every megabyte for longer relocations.
xadd := uint32(xadd)
o0 |= (xadd&3)<<29 | (xadd&0xffffc)<<3
switch rt {
case objabi.R_ARM64_PCREL_LDST8, objabi.R_ADDRARM64:
o1 |= (xadd & 0xfff) << 10
case objabi.R_ARM64_PCREL_LDST16:
if xadd&0x1 != 0 {
ldr.Errorf(s, "offset for 16-bit load/store has unaligned value %d", xadd&0xfff)
}
o1 |= ((xadd & 0xfff) >> 1) << 10
case objabi.R_ARM64_PCREL_LDST32:
if xadd&0x3 != 0 {
ldr.Errorf(s, "offset for 32-bit load/store has unaligned value %d", xadd&0xfff)
}
o1 |= ((xadd & 0xfff) >> 2) << 10
case objabi.R_ARM64_PCREL_LDST64:
if xadd&0x7 != 0 {
ldr.Errorf(s, "offset for 64-bit load/store has unaligned value %d", xadd&0xfff)
}
o1 |= ((xadd & 0xfff) >> 3) << 10
}
if target.IsBigEndian() {
val = int64(o0)<<32 | int64(o1)
} else {
val = int64(o1)<<32 | int64(o0)
}
}
return val, nExtReloc, isOk
case objabi.R_CALLARM64:
nExtReloc = 1
return val, nExtReloc, isOk
case objabi.R_ARM64_TLS_LE:
nExtReloc = 1
return val, nExtReloc, isOk
case objabi.R_ARM64_TLS_IE:
nExtReloc = 2 // need two ELF relocations. see elfreloc1
return val, nExtReloc, isOk
case objabi.R_ADDR:
if target.IsWindows() && r.Add() != 0 {
if r.Siz() == 8 {
val = r.Add()
} else if target.IsBigEndian() {
val = int64(uint32(val)) | int64(r.Add())<<32
} else {
val = val>>32<<32 | int64(uint32(r.Add()))
}
return val, 1, true
}
}
}
switch rt := r.Type(); rt {
case objabi.R_ADDRARM64,
objabi.R_ARM64_PCREL_LDST8,
objabi.R_ARM64_PCREL_LDST16,
objabi.R_ARM64_PCREL_LDST32,
objabi.R_ARM64_PCREL_LDST64:
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t >= 1<<32 || t < -1<<32 {
ldr.Errorf(s, "program too large, address relocation distance = %d", t)
}
var o0, o1 uint32
if target.IsBigEndian() {
o0 = uint32(val >> 32)
o1 = uint32(val)
} else {
o0 = uint32(val)
o1 = uint32(val >> 32)
}
o0 |= (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
switch rt {
case objabi.R_ARM64_PCREL_LDST8, objabi.R_ADDRARM64:
o1 |= uint32(t&0xfff) << 10
case objabi.R_ARM64_PCREL_LDST16:
if t&0x1 != 0 {
ldr.Errorf(s, "offset for 16-bit load/store has unaligned value %d", t&0xfff)
}
o1 |= (uint32(t&0xfff) >> 1) << 10
case objabi.R_ARM64_PCREL_LDST32:
if t&0x3 != 0 {
ldr.Errorf(s, "offset for 32-bit load/store has unaligned value %d", t&0xfff)
}
o1 |= (uint32(t&0xfff) >> 2) << 10
case objabi.R_ARM64_PCREL_LDST64:
if t&0x7 != 0 {
ldr.Errorf(s, "offset for 64-bit load/store has unaligned value %d", t&0xfff)
}
o1 |= (uint32(t&0xfff) >> 3) << 10
}
// when laid out, the instruction order must always be o1, o2.
if target.IsBigEndian() {
return int64(o0)<<32 | int64(o1), noExtReloc, true
}
return int64(o1)<<32 | int64(o0), noExtReloc, true
case objabi.R_ARM64_TLS_LE:
if target.IsDarwin() {
ldr.Errorf(s, "TLS reloc on unsupported OS %v", target.HeadType)
}
// The TCB is two pointers. This is not documented anywhere, but is
// de facto part of the ABI.
v := ldr.SymValue(rs) + int64(2*target.Arch.PtrSize)
if v < 0 || v >= 32678 {
ldr.Errorf(s, "TLS offset out of range %d", v)
}
return val | (v << 5), noExtReloc, true
case objabi.R_ARM64_TLS_IE:
if target.IsPIE() && target.IsElf() {
// We are linking the final executable, so we
// can optimize any TLS IE relocation to LE.
if !target.IsLinux() {
ldr.Errorf(s, "TLS reloc on unsupported OS %v", target.HeadType)
}
// The TCB is two pointers. This is not documented anywhere, but is
// de facto part of the ABI.
v := ldr.SymAddr(rs) + int64(2*target.Arch.PtrSize) + r.Add()
if v < 0 || v >= 32678 {
ldr.Errorf(s, "TLS offset out of range %d", v)
}
var o0, o1 uint32
if target.IsBigEndian() {
o0 = uint32(val >> 32)
o1 = uint32(val)
} else {
o0 = uint32(val)
o1 = uint32(val >> 32)
}
// R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21
// turn ADRP to MOVZ
o0 = 0xd2a00000 | uint32(o0&0x1f) | (uint32((v>>16)&0xffff) << 5)
// R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC
// turn LD64 to MOVK
if v&3 != 0 {
ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC", v)
}
o1 = 0xf2800000 | uint32(o1&0x1f) | (uint32(v&0xffff) << 5)
// when laid out, the instruction order must always be o0, o1.
if target.IsBigEndian() {
return int64(o0)<<32 | int64(o1), noExtReloc, isOk
}
return int64(o1)<<32 | int64(o0), noExtReloc, isOk
} else {
log.Fatalf("cannot handle R_ARM64_TLS_IE (sym %s) when linking internally", ldr.SymName(s))
}
case objabi.R_CALLARM64:
var t int64
if ldr.SymType(rs) == sym.SDYNIMPORT {
t = (ldr.SymAddr(syms.PLT) + r.Add()) - (ldr.SymValue(s) + int64(r.Off()))
} else {
t = (ldr.SymAddr(rs) + r.Add()) - (ldr.SymValue(s) + int64(r.Off()))
}
if t >= 1<<27 || t < -1<<27 {
ldr.Errorf(s, "program too large, call relocation distance = %d", t)
}
return val | ((t >> 2) & 0x03ffffff), noExtReloc, true
case objabi.R_ARM64_GOT:
if (val>>24)&0x9f == 0x90 {
// R_AARCH64_ADR_GOT_PAGE
// patch instruction: adrp
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t >= 1<<32 || t < -1<<32 {
ldr.Errorf(s, "program too large, address relocation distance = %d", t)
}
var o0 uint32
o0 |= (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
return val | int64(o0), noExtReloc, isOk
} else if val>>24 == 0xf9 {
// R_AARCH64_LD64_GOT_LO12_NC
// patch instruction: ldr
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t&7 != 0 {
ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LD64_GOT_LO12_NC", t)
}
var o1 uint32
o1 |= uint32(t&0xfff) << (10 - 3)
return val | int64(uint64(o1)), noExtReloc, isOk
} else {
ldr.Errorf(s, "unsupported instruction for %x R_GOTARM64", val)
}
case objabi.R_ARM64_PCREL:
if (val>>24)&0x9f == 0x90 {
// R_AARCH64_ADR_PREL_PG_HI21
// patch instruction: adrp
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t >= 1<<32 || t < -1<<32 {
ldr.Errorf(s, "program too large, address relocation distance = %d", t)
}
o0 := (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
return val | int64(o0), noExtReloc, isOk
} else if (val>>24)&0x9f == 0x91 {
// ELF R_AARCH64_ADD_ABS_LO12_NC or Mach-O ARM64_RELOC_PAGEOFF12
// patch instruction: add
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
o1 := uint32(t&0xfff) << 10
return val | int64(o1), noExtReloc, isOk
} else if (val>>24)&0x3b == 0x39 {
// Mach-O ARM64_RELOC_PAGEOFF12
// patch ldr/str(b/h/w/d/q) (integer or vector) instructions, which have different scaling factors.
// Mach-O uses same relocation type for them.
shift := uint32(val) >> 30
if shift == 0 && (val>>20)&0x048 == 0x048 { // 128-bit vector load
shift = 4
}
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t&(1<<shift-1) != 0 {
ldr.Errorf(s, "invalid address: %x for relocation type: ARM64_RELOC_PAGEOFF12", t)
}
o1 := (uint32(t&0xfff) >> shift) << 10
return val | int64(o1), noExtReloc, isOk
} else {
ldr.Errorf(s, "unsupported instruction for %x R_ARM64_PCREL", val)
}
case objabi.R_ARM64_LDST8:
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
o0 := uint32(t&0xfff) << 10
return val | int64(o0), noExtReloc, true
case objabi.R_ARM64_LDST16:
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t&1 != 0 {
ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST16_ABS_LO12_NC", t)
}
o0 := (uint32(t&0xfff) >> 1) << 10
return val | int64(o0), noExtReloc, true
case objabi.R_ARM64_LDST32:
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t&3 != 0 {
ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST32_ABS_LO12_NC", t)
}
o0 := (uint32(t&0xfff) >> 2) << 10
return val | int64(o0), noExtReloc, true
case objabi.R_ARM64_LDST64:
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t&7 != 0 {
ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST64_ABS_LO12_NC", t)
}
o0 := (uint32(t&0xfff) >> 3) << 10
return val | int64(o0), noExtReloc, true
case objabi.R_ARM64_LDST128:
t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
if t&15 != 0 {
ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST128_ABS_LO12_NC", t)
}
o0 := (uint32(t&0xfff) >> 4) << 10
return val | int64(o0), noExtReloc, true
}
return val, 0, false
}
func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
log.Fatalf("unexpected relocation variant")
return -1
}
func extreloc(target *ld.Target, ldr *loader.Loader, r loader.Reloc, s loader.Sym) (loader.ExtReloc, bool) {
switch rt := r.Type(); rt {
case objabi.R_ARM64_GOTPCREL,
objabi.R_ARM64_PCREL_LDST8,
objabi.R_ARM64_PCREL_LDST16,
objabi.R_ARM64_PCREL_LDST32,
objabi.R_ARM64_PCREL_LDST64,
objabi.R_ADDRARM64:
rr := ld.ExtrelocViaOuterSym(ldr, r, s)
return rr, true
case objabi.R_CALLARM64,
objabi.R_ARM64_TLS_LE,
objabi.R_ARM64_TLS_IE:
return ld.ExtrelocSimple(ldr, r), true
}
return loader.ExtReloc{}, false
}
func elfsetupplt(ctxt *ld.Link, ldr *loader.Loader, plt, gotplt *loader.SymbolBuilder, dynamic loader.Sym) {
if plt.Size() == 0 {
// stp x16, x30, [sp, #-16]!
// identifying information
plt.AddUint32(ctxt.Arch, 0xa9bf7bf0)
// the following two instructions (adrp + ldr) load *got[2] into x17
// adrp x16, &got[0]
plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_GOT, 4)
plt.SetUint32(ctxt.Arch, plt.Size()-4, 0x90000010)
// <imm> is the offset value of &got[2] to &got[0], the same below
// ldr x17, [x16, <imm>]
plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_GOT, 4)
plt.SetUint32(ctxt.Arch, plt.Size()-4, 0xf9400211)
// add x16, x16, <imm>
plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_PCREL, 4)
plt.SetUint32(ctxt.Arch, plt.Size()-4, 0x91000210)
// br x17
plt.AddUint32(ctxt.Arch, 0xd61f0220)
// 3 nop for place holder
plt.AddUint32(ctxt.Arch, 0xd503201f)
plt.AddUint32(ctxt.Arch, 0xd503201f)
plt.AddUint32(ctxt.Arch, 0xd503201f)
// check gotplt.size == 0
if gotplt.Size() != 0 {
ctxt.Errorf(gotplt.Sym(), "got.plt is not empty at the very beginning")
}
gotplt.AddAddrPlus(ctxt.Arch, dynamic, 0)
gotplt.AddUint64(ctxt.Arch, 0)
gotplt.AddUint64(ctxt.Arch, 0)
}
}
func addpltsym(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym) {
if ldr.SymPlt(s) >= 0 {
return
}
ld.Adddynsym(ldr, target, syms, s)
if target.IsElf() {
plt := ldr.MakeSymbolUpdater(syms.PLT)
gotplt := ldr.MakeSymbolUpdater(syms.GOTPLT)
rela := ldr.MakeSymbolUpdater(syms.RelaPLT)
if plt.Size() == 0 {
panic("plt is not set up")
}
// adrp x16, &got.plt[0]
plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
plt.SetUint32(target.Arch, plt.Size()-4, 0x90000010)
relocs := plt.Relocs()
plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_GOT)
// <offset> is the offset value of &got.plt[n] to &got.plt[0]
// ldr x17, [x16, <offset>]
plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
plt.SetUint32(target.Arch, plt.Size()-4, 0xf9400211)
relocs = plt.Relocs()
plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_GOT)
// add x16, x16, <offset>
plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
plt.SetUint32(target.Arch, plt.Size()-4, 0x91000210)
relocs = plt.Relocs()
plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_PCREL)
// br x17
plt.AddUint32(target.Arch, 0xd61f0220)
// add to got.plt: pointer to plt[0]
gotplt.AddAddrPlus(target.Arch, plt.Sym(), 0)
// rela
rela.AddAddrPlus(target.Arch, gotplt.Sym(), gotplt.Size()-8)
sDynid := ldr.SymDynid(s)
rela.AddUint64(target.Arch, elf.R_INFO(uint32(sDynid), uint32(elf.R_AARCH64_JUMP_SLOT)))
rela.AddUint64(target.Arch, 0)
ldr.SetPlt(s, int32(plt.Size()-16))
} else if target.IsDarwin() {
ld.AddGotSym(target, ldr, syms, s, 0)
sDynid := ldr.SymDynid(s)
lep := ldr.MakeSymbolUpdater(syms.LinkEditPLT)
lep.AddUint32(target.Arch, uint32(sDynid))
plt := ldr.MakeSymbolUpdater(syms.PLT)
ldr.SetPlt(s, int32(plt.Size()))
// adrp x16, GOT
plt.AddUint32(target.Arch, 0x90000010)
r, _ := plt.AddRel(objabi.R_ARM64_GOT)
r.SetOff(int32(plt.Size() - 4))
r.SetSiz(4)
r.SetSym(syms.GOT)
r.SetAdd(int64(ldr.SymGot(s)))
// ldr x17, [x16, <offset>]
plt.AddUint32(target.Arch, 0xf9400211)
r, _ = plt.AddRel(objabi.R_ARM64_GOT)
r.SetOff(int32(plt.Size() - 4))
r.SetSiz(4)
r.SetSym(syms.GOT)
r.SetAdd(int64(ldr.SymGot(s)))
// br x17
plt.AddUint32(target.Arch, 0xd61f0220)
} else {
ldr.Errorf(s, "addpltsym: unsupported binary format")
}
}
const (
machoRelocLimit = 1 << 23
peRelocLimit = 1 << 20
)
func gensymlate(ctxt *ld.Link, ldr *loader.Loader) {
// When external linking on darwin, Mach-O relocation has only signed 24-bit
// addend. For large symbols, we generate "label" symbols in the middle, so
// that relocations can target them with smaller addends.
// On Windows, we only get 21 bits, again (presumably) signed.
// Also, on Windows (always) and Darwin (for very large binaries), the external
// linker doesn't support CALL relocations with addend, so we generate "label"
// symbols for functions of which we can target the middle (Duff's devices).
if !ctxt.IsDarwin() && !ctxt.IsWindows() || !ctxt.IsExternal() {
return
}
limit := int64(machoRelocLimit)
if ctxt.IsWindows() {
limit = peRelocLimit
}
// addLabelSyms adds "label" symbols at s+limit, s+2*limit, etc.
addLabelSyms := func(s loader.Sym, limit, sz int64) {
v := ldr.SymValue(s)
for off := limit; off < sz; off += limit {
p := ldr.LookupOrCreateSym(offsetLabelName(ldr, s, off), ldr.SymVersion(s))
ldr.SetAttrReachable(p, true)
ldr.SetSymValue(p, v+off)
ldr.SetSymSect(p, ldr.SymSect(s))
if ctxt.IsDarwin() {
ld.AddMachoSym(ldr, p)
} else if ctxt.IsWindows() {
ld.AddPELabelSym(ldr, p)
} else {
panic("missing case in gensymlate")
}
// fmt.Printf("gensymlate %s %x\n", ldr.SymName(p), ldr.SymValue(p))
}
}
// Generate symbol names for every offset we need in duffcopy/duffzero (only 64 each).
if s := ldr.Lookup("runtime.duffcopy", sym.SymVerABIInternal); s != 0 && ldr.AttrReachable(s) {
addLabelSyms(s, 8, 8*64)
}
if s := ldr.Lookup("runtime.duffzero", sym.SymVerABIInternal); s != 0 && ldr.AttrReachable(s) {
addLabelSyms(s, 4, 4*64)
}
if ctxt.IsDarwin() {
big := false
for _, seg := range ld.Segments {
if seg.Length >= machoRelocLimit {
big = true
break
}
}
if !big {
return // skip work if nothing big
}
}
for s, n := loader.Sym(1), loader.Sym(ldr.NSym()); s < n; s++ {
if !ldr.AttrReachable(s) {
continue
}
t := ldr.SymType(s)
if t.IsText() {
// Except for Duff's devices (handled above), we don't
// target the middle of a function.
continue
}
if t >= sym.SDWARFSECT {
continue // no need to add label for DWARF symbols
}
sz := ldr.SymSize(s)
if sz <= limit {
continue
}
addLabelSyms(s, limit, sz)
}
// Also for carrier symbols (for which SymSize is 0)
for _, ss := range ld.CarrierSymByType {
if ss.Sym != 0 && ss.Size > limit {
addLabelSyms(ss.Sym, limit, ss.Size)
}
}
}
// offsetLabelName returns the name of the "label" symbol used for a
// relocation targeting s+off. The label symbols is used on Darwin/Windows
// when external linking, so that the addend fits in a Mach-O/PE relocation.
func offsetLabelName(ldr *loader.Loader, s loader.Sym, off int64) string {
if off>>20<<20 == off {
return fmt.Sprintf("%s+%dMB", ldr.SymExtname(s), off>>20)
}
return fmt.Sprintf("%s+%d", ldr.SymExtname(s), off)
}
// Convert the direct jump relocation r to refer to a trampoline if the target is too far.
func trampoline(ctxt *ld.Link, ldr *loader.Loader, ri int, rs, s loader.Sym) {
relocs := ldr.Relocs(s)
r := relocs.At(ri)
const pcrel = 1
switch r.Type() {
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_CALL26),
objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_JUMP26),
objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_BRANCH26*2 + pcrel:
// Host object relocations that will be turned into a PLT call.
// The PLT may be too far. Insert a trampoline for them.
fallthrough
case objabi.R_CALLARM64:
var t int64
// ldr.SymValue(rs) == 0 indicates a cross-package jump to a function that is not yet
// laid out. Conservatively use a trampoline. This should be rare, as we lay out packages
// in dependency order.
if ldr.SymValue(rs) != 0 {
t = ldr.SymValue(rs) + r.Add() - (ldr.SymValue(s) + int64(r.Off()))
}
if t >= 1<<27 || t < -1<<27 || ldr.SymValue(rs) == 0 || (*ld.FlagDebugTramp > 1 && (ldr.SymPkg(s) == "" || ldr.SymPkg(s) != ldr.SymPkg(rs))) {
// direct call too far, need to insert trampoline.
// look up existing trampolines first. if we found one within the range
// of direct call, we can reuse it. otherwise create a new one.
var tramp loader.Sym
for i := 0; ; i++ {
oName := ldr.SymName(rs)
name := oName + fmt.Sprintf("%+x-tramp%d", r.Add(), i)
tramp = ldr.LookupOrCreateSym(name, int(ldr.SymVersion(rs)))
ldr.SetAttrReachable(tramp, true)
if ldr.SymType(tramp) == sym.SDYNIMPORT {
// don't reuse trampoline defined in other module
continue
}
if oName == "runtime.deferreturn" {
ldr.SetIsDeferReturnTramp(tramp, true)
}
if ldr.SymValue(tramp) == 0 {
// either the trampoline does not exist -- we need to create one,
// or found one the address which is not assigned -- this will be
// laid down immediately after the current function. use this one.
break
}
t = ldr.SymValue(tramp) - (ldr.SymValue(s) + int64(r.Off()))
if t >= -1<<27 && t < 1<<27 {
// found an existing trampoline that is not too far
// we can just use it
break
}
}
if ldr.SymType(tramp) == 0 {
// trampoline does not exist, create one
trampb := ldr.MakeSymbolUpdater(tramp)
ctxt.AddTramp(trampb, ldr.SymType(s))
if ldr.SymType(rs) == sym.SDYNIMPORT {
if r.Add() != 0 {
ctxt.Errorf(s, "nonzero addend for DYNIMPORT call: %v+%d", ldr.SymName(rs), r.Add())
}
gentrampgot(ctxt, ldr, trampb, rs)
} else {
gentramp(ctxt, ldr, trampb, rs, r.Add())
}
}
// modify reloc to point to tramp, which will be resolved later
sb := ldr.MakeSymbolUpdater(s)
relocs := sb.Relocs()
r := relocs.At(ri)
r.SetSym(tramp)
r.SetAdd(0) // clear the offset embedded in the instruction
}
default:
ctxt.Errorf(s, "trampoline called with non-jump reloc: %d (%s)", r.Type(), sym.RelocName(ctxt.Arch, r.Type()))
}
}
// generate a trampoline to target+offset.
func gentramp(ctxt *ld.Link, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) {
tramp.SetSize(12) // 3 instructions
P := make([]byte, tramp.Size())
o1 := uint32(0x90000010) // adrp x16, target
o2 := uint32(0x91000210) // add x16, pc-relative-offset
o3 := uint32(0xd61f0200) // br x16
ctxt.Arch.ByteOrder.PutUint32(P, o1)
ctxt.Arch.ByteOrder.PutUint32(P[4:], o2)
ctxt.Arch.ByteOrder.PutUint32(P[8:], o3)
tramp.SetData(P)
r, _ := tramp.AddRel(objabi.R_ADDRARM64)
r.SetSiz(8)
r.SetSym(target)
r.SetAdd(offset)
}
// generate a trampoline to target+offset for a DYNIMPORT symbol via GOT.
func gentrampgot(ctxt *ld.Link, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym) {
tramp.SetSize(12) // 3 instructions
P := make([]byte, tramp.Size())
o1 := uint32(0x90000010) // adrp x16, target@GOT
o2 := uint32(0xf9400210) // ldr x16, [x16, offset]
o3 := uint32(0xd61f0200) // br x16
ctxt.Arch.ByteOrder.PutUint32(P, o1)
ctxt.Arch.ByteOrder.PutUint32(P[4:], o2)
ctxt.Arch.ByteOrder.PutUint32(P[8:], o3)
tramp.SetData(P)
r, _ := tramp.AddRel(objabi.R_ARM64_GOTPCREL)
r.SetSiz(8)
r.SetSym(target)
}