func genaddmoduledata(ctxt *ld.Link) {
addmoduledata := ctxt.Syms.ROLookup("runtime.addmoduledata", 0)
if addmoduledata.Type == obj.STEXT {
return
}
addmoduledata.Attr |= ld.AttrReachable
initfunc := ctxt.Syms.Lookup("go.link.addmoduledata", 0)
initfunc.Type = obj.STEXT
initfunc.Attr |= ld.AttrLocal
initfunc.Attr |= ld.AttrReachable
o := func(op uint32) {
ld.Adduint32(ctxt, initfunc, op)
}
// addis r2, r12, .TOC.-func@ha
rel := ld.Addrel(initfunc)
rel.Off = int32(initfunc.Size)
rel.Siz = 8
rel.Sym = ctxt.Syms.Lookup(".TOC.", 0)
rel.Type = obj.R_ADDRPOWER_PCREL
o(0x3c4c0000)
// addi r2, r2, .TOC.-func@l
o(0x38420000)
// mflr r31
o(0x7c0802a6)
// stdu r31, -32(r1)
o(0xf801ffe1)
// addis r3, r2, local.moduledata@got@ha
rel = ld.Addrel(initfunc)
rel.Off = int32(initfunc.Size)
rel.Siz = 8
rel.Sym = ctxt.Syms.Lookup("local.moduledata", 0)
rel.Type = obj.R_ADDRPOWER_GOT
o(0x3c620000)
// ld r3, local.moduledata@got@l(r3)
o(0xe8630000)
// bl runtime.addmoduledata
rel = ld.Addrel(initfunc)
rel.Off = int32(initfunc.Size)
rel.Siz = 4
rel.Sym = addmoduledata
rel.Type = obj.R_CALLPOWER
o(0x48000001)
// nop
o(0x60000000)
// ld r31, 0(r1)
o(0xe8010000)
// mtlr r31
o(0x7c0803a6)
// addi r1,r1,32
o(0x38210020)
// blr
o(0x4e800020)
ctxt.Textp = append(ctxt.Textp, initfunc)
initarray_entry := ctxt.Syms.Lookup("go.link.addmoduledatainit", 0)
initarray_entry.Attr |= ld.AttrReachable
initarray_entry.Attr |= ld.AttrLocal
initarray_entry.Type = obj.SINITARR
ld.Addaddr(ctxt, initarray_entry, initfunc)
}
func gentext(ctxt *ld.Link) {
if !ctxt.DynlinkingGo() {
return
}
addmoduledata := ctxt.Syms.Lookup("runtime.addmoduledata", 0)
if addmoduledata.Type == obj.STEXT && ld.Buildmode != ld.BuildmodePlugin {
// we're linking a module containing the runtime -> no need for
// an init function
return
}
addmoduledata.Attr |= ld.AttrReachable
initfunc := ctxt.Syms.Lookup("go.link.addmoduledata", 0)
initfunc.Type = obj.STEXT
initfunc.Attr |= ld.AttrLocal
initfunc.Attr |= ld.AttrReachable
o := func(op uint32) {
ld.Adduint32(ctxt, initfunc, op)
}
o(0xe59f0004)
o(0xe08f0000)
o(0xeafffffe)
rel := ld.Addrel(initfunc)
rel.Off = 8
rel.Siz = 4
rel.Sym = ctxt.Syms.Lookup("runtime.addmoduledata", 0)
rel.Type = obj.R_CALLARM
rel.Add = 0xeafffffe // vomit
o(0x00000000)
rel = ld.Addrel(initfunc)
rel.Off = 12
rel.Siz = 4
rel.Sym = ctxt.Moduledata
rel.Type = obj.R_PCREL
rel.Add = 4
if ld.Buildmode == ld.BuildmodePlugin {
ctxt.Textp = append(ctxt.Textp, addmoduledata)
}
ctxt.Textp = append(ctxt.Textp, initfunc)
initarray_entry := ctxt.Syms.Lookup("go.link.addmoduledatainit", 0)
initarray_entry.Attr |= ld.AttrReachable
initarray_entry.Attr |= ld.AttrLocal
initarray_entry.Type = obj.SINITARR
ld.Addaddr(ctxt, initarray_entry, initfunc)
}
func gentext(ctxt *ld.Link) {
if !ctxt.DynlinkingGo() {
return
}
addmoduledata := ctxt.Syms.Lookup("runtime.addmoduledata", 0)
if addmoduledata.Type == obj.STEXT && ld.Buildmode != ld.BuildmodePlugin {
// we're linking a module containing the runtime -> no need for
// an init function
return
}
addmoduledata.Attr |= ld.AttrReachable
initfunc := ctxt.Syms.Lookup("go.link.addmoduledata", 0)
initfunc.Type = obj.STEXT
initfunc.Attr |= ld.AttrLocal
initfunc.Attr |= ld.AttrReachable
o := func(op ...uint8) {
for _, op1 := range op {
ld.Adduint8(ctxt, initfunc, op1)
}
}
// 0000000000000000 <local.dso_init>:
// 0: 48 8d 3d 00 00 00 00 lea 0x0(%rip),%rdi # 7 <local.dso_init+0x7>
// 3: R_X86_64_PC32 runtime.firstmoduledata-0x4
o(0x48, 0x8d, 0x3d)
ld.Addpcrelplus(ctxt, initfunc, ctxt.Moduledata, 0)
// 7: e8 00 00 00 00 callq c <local.dso_init+0xc>
// 8: R_X86_64_PLT32 runtime.addmoduledata-0x4
o(0xe8)
Addcall(ctxt, initfunc, addmoduledata)
// c: c3 retq
o(0xc3)
if ld.Buildmode == ld.BuildmodePlugin {
ctxt.Textp = append(ctxt.Textp, addmoduledata)
}
ctxt.Textp = append(ctxt.Textp, initfunc)
initarray_entry := ctxt.Syms.Lookup("go.link.addmoduledatainit", 0)
initarray_entry.Attr |= ld.AttrReachable
initarray_entry.Attr |= ld.AttrLocal
initarray_entry.Type = obj.SINITARR
ld.Addaddr(ctxt, initarray_entry, initfunc)
}
// gentext generates assembly to append the local moduledata to the global
// moduledata linked list at initialization time. This is only done if the runtime
// is in a different module.
//
// <go.link.addmoduledata>:
// larl %r2, <local.moduledata>
// jg <runtime.addmoduledata@plt>
// undef
//
// The job of appending the moduledata is delegated to runtime.addmoduledata.
func gentext(ctxt *ld.Link) {
if !ld.DynlinkingGo() {
return
}
addmoduledata := ld.Linklookup(ctxt, "runtime.addmoduledata", 0)
if addmoduledata.Type == obj.STEXT {
// we're linking a module containing the runtime -> no need for
// an init function
return
}
addmoduledata.Attr |= ld.AttrReachable
initfunc := ld.Linklookup(ctxt, "go.link.addmoduledata", 0)
initfunc.Type = obj.STEXT
initfunc.Attr |= ld.AttrLocal
initfunc.Attr |= ld.AttrReachable
// larl %r2, <local.moduledata>
ld.Adduint8(ctxt, initfunc, 0xc0)
ld.Adduint8(ctxt, initfunc, 0x20)
lmd := ld.Addrel(initfunc)
lmd.Off = int32(initfunc.Size)
lmd.Siz = 4
lmd.Sym = ctxt.Moduledata
lmd.Type = obj.R_PCREL
lmd.Variant = ld.RV_390_DBL
lmd.Add = 2 + int64(lmd.Siz)
ld.Adduint32(ctxt, initfunc, 0)
// jg <runtime.addmoduledata[@plt]>
ld.Adduint8(ctxt, initfunc, 0xc0)
ld.Adduint8(ctxt, initfunc, 0xf4)
rel := ld.Addrel(initfunc)
rel.Off = int32(initfunc.Size)
rel.Siz = 4
rel.Sym = ld.Linklookup(ctxt, "runtime.addmoduledata", 0)
rel.Type = obj.R_CALL
rel.Variant = ld.RV_390_DBL
rel.Add = 2 + int64(rel.Siz)
ld.Adduint32(ctxt, initfunc, 0)
// undef (for debugging)
ld.Adduint32(ctxt, initfunc, 0)
ctxt.Textp = append(ctxt.Textp, initfunc)
initarray_entry := ld.Linklookup(ctxt, "go.link.addmoduledatainit", 0)
initarray_entry.Attr |= ld.AttrLocal
initarray_entry.Attr |= ld.AttrReachable
initarray_entry.Type = obj.SINITARR
ld.Addaddr(ctxt, initarray_entry, initfunc)
}
func gentext(ctxt *ld.Link) {
if !ctxt.DynlinkingGo() {
return
}
addmoduledata := ctxt.Syms.Lookup("runtime.addmoduledata", 0)
if addmoduledata.Type == obj.STEXT {
// we're linking a module containing the runtime -> no need for
// an init function
return
}
addmoduledata.Attr |= ld.AttrReachable
initfunc := ctxt.Syms.Lookup("go.link.addmoduledata", 0)
initfunc.Type = obj.STEXT
initfunc.Attr |= ld.AttrLocal
initfunc.Attr |= ld.AttrReachable
o := func(op uint32) {
ld.Adduint32(ctxt, initfunc, 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 := ld.Addrel(initfunc)
rel.Off = 0
rel.Siz = 8
rel.Sym = ctxt.Moduledata
rel.Type = obj.R_ADDRARM64
// 8: 14000000 bl 0 <runtime.addmoduledata>
// 8: R_AARCH64_CALL26 runtime.addmoduledata
o(0x14000000)
rel = ld.Addrel(initfunc)
rel.Off = 8
rel.Siz = 4
rel.Sym = ctxt.Syms.Lookup("runtime.addmoduledata", 0)
rel.Type = obj.R_CALLARM64 // Really should be R_AARCH64_JUMP26 but doesn't seem to make any difference
ctxt.Textp = append(ctxt.Textp, initfunc)
initarray_entry := ctxt.Syms.Lookup("go.link.addmoduledatainit", 0)
initarray_entry.Attr |= ld.AttrReachable
initarray_entry.Attr |= ld.AttrLocal
initarray_entry.Type = obj.SINITARR
ld.Addaddr(ctxt, initarray_entry, initfunc)
}
func gentext(ctxt *ld.Link) {
if !ld.DynlinkingGo() && ld.Buildmode != ld.BuildmodePIE && ld.Buildmode != ld.BuildmodeCShared {
return
}
// Generate little thunks that load the PC of the next instruction into a register.
for _, r := range [...]struct {
name string
num uint8
}{
{"ax", 0},
{"cx", 1},
{"dx", 2},
{"bx", 3},
// sp
{"bp", 5},
{"si", 6},
{"di", 7},
} {
thunkfunc := ld.Linklookup(ctxt, "__x86.get_pc_thunk."+r.name, 0)
thunkfunc.Type = obj.STEXT
thunkfunc.Attr |= ld.AttrLocal
thunkfunc.Attr |= ld.AttrReachable //TODO: remove?
o := func(op ...uint8) {
for _, op1 := range op {
ld.Adduint8(ctxt, thunkfunc, op1)
}
}
// 8b 04 24 mov (%esp),%eax
// Destination register is in bits 3-5 of the middle byte, so add that in.
o(0x8b, 0x04+r.num<<3, 0x24)
// c3 ret
o(0xc3)
ctxt.Textp = append(ctxt.Textp, thunkfunc)
}
addmoduledata := ld.Linklookup(ctxt, "runtime.addmoduledata", 0)
if addmoduledata.Type == obj.STEXT {
// we're linking a module containing the runtime -> no need for
// an init function
return
}
addmoduledata.Attr |= ld.AttrReachable
initfunc := ld.Linklookup(ctxt, "go.link.addmoduledata", 0)
initfunc.Type = obj.STEXT
initfunc.Attr |= ld.AttrLocal
initfunc.Attr |= ld.AttrReachable
o := func(op ...uint8) {
for _, op1 := range op {
ld.Adduint8(ctxt, initfunc, op1)
}
}
// go.link.addmoduledata:
// 53 push %ebx
// e8 00 00 00 00 call __x86.get_pc_thunk.cx + R_CALL __x86.get_pc_thunk.cx
// 8d 81 00 00 00 00 lea 0x0(%ecx), %eax + R_PCREL ctxt.Moduledata
// 8d 99 00 00 00 00 lea 0x0(%ecx), %ebx + R_GOTPC _GLOBAL_OFFSET_TABLE_
// e8 00 00 00 00 call runtime.addmoduledata@plt + R_CALL runtime.addmoduledata
// 5b pop %ebx
// c3 ret
o(0x53)
o(0xe8)
addcall(ctxt, initfunc, ld.Linklookup(ctxt, "__x86.get_pc_thunk.cx", 0))
o(0x8d, 0x81)
ld.Addpcrelplus(ctxt, initfunc, ctxt.Moduledata, 6)
o(0x8d, 0x99)
i := initfunc.Size
initfunc.Size += 4
ld.Symgrow(ctxt, initfunc, initfunc.Size)
r := ld.Addrel(initfunc)
r.Sym = ld.Linklookup(ctxt, "_GLOBAL_OFFSET_TABLE_", 0)
r.Off = int32(i)
r.Type = obj.R_PCREL
r.Add = 12
r.Siz = 4
o(0xe8)
addcall(ctxt, initfunc, addmoduledata)
o(0x5b)
o(0xc3)
ctxt.Textp = append(ctxt.Textp, initfunc)
initarray_entry := ld.Linklookup(ctxt, "go.link.addmoduledatainit", 0)
initarray_entry.Attr |= ld.AttrReachable
initarray_entry.Attr |= ld.AttrLocal
initarray_entry.Type = obj.SINITARR
ld.Addaddr(ctxt, initarray_entry, initfunc)
}
func genplt(ctxt *ld.Link) {
// The ppc64 ABI PLT has similar concepts to other
// architectures, but is laid out quite differently. When we
// see an R_PPC64_REL24 relocation to a dynamic symbol
// (indicating that the call needs to go through the PLT), we
// generate up to three stubs and reserve a PLT slot.
//
// 1) The call site will be bl x; nop (where the relocation
// applies to the bl). We rewrite this to bl x_stub; ld
// r2,24(r1). The ld is necessary because x_stub will save
// r2 (the TOC pointer) at 24(r1) (the "TOC save slot").
//
// 2) We reserve space for a pointer in the .plt section (once
// per referenced dynamic function). .plt is a data
// section filled solely by the dynamic linker (more like
// .plt.got on other architectures). Initially, the
// dynamic linker will fill each slot with a pointer to the
// corresponding x@plt entry point.
//
// 3) We generate the "call stub" x_stub (once per dynamic
// function/object file pair). This saves the TOC in the
// TOC save slot, reads the function pointer from x's .plt
// slot and calls it like any other global entry point
// (including setting r12 to the function address).
//
// 4) We generate the "symbol resolver stub" x@plt (once per
// dynamic function). This is solely a branch to the glink
// resolver stub.
//
// 5) We generate the glink resolver stub (only once). This
// computes which symbol resolver stub we came through and
// invokes the dynamic resolver via a pointer provided by
// the dynamic linker. This will patch up the .plt slot to
// point directly at the function so future calls go
// straight from the call stub to the real function, and
// then call the function.
// NOTE: It's possible we could make ppc64 closer to other
// architectures: ppc64's .plt is like .plt.got on other
// platforms and ppc64's .glink is like .plt on other
// platforms.
// Find all R_PPC64_REL24 relocations that reference dynamic
// imports. Reserve PLT entries for these symbols and
// generate call stubs. The call stubs need to live in .text,
// which is why we need to do this pass this early.
//
// This assumes "case 1" from the ABI, where the caller needs
// us to save and restore the TOC pointer.
for _, s := range ctxt.Textp {
for i := range s.R {
r := &s.R[i]
if r.Type != 256+ld.R_PPC64_REL24 || r.Sym.Type != obj.SDYNIMPORT {
continue
}
// Reserve PLT entry and generate symbol
// resolver
addpltsym(ctxt, r.Sym)
// Generate call stub
n := fmt.Sprintf("%s.%s", s.Name, r.Sym.Name)
stub := ctxt.Syms.Lookup(n, 0)
if s.Attr.Reachable() {
stub.Attr |= ld.AttrReachable
}
if stub.Size == 0 {
// Need outer to resolve .TOC.
stub.Outer = s
ctxt.Textp = append(ctxt.Textp, stub)
gencallstub(ctxt, 1, stub, r.Sym)
}
// Update the relocation to use the call stub
r.Sym = stub
// Restore TOC after bl. The compiler put a
// nop here for us to overwrite.
const o1 = 0xe8410018 // ld r2,24(r1)
ctxt.Arch.ByteOrder.PutUint32(s.P[r.Off+4:], o1)
}
}
}