diff options
Diffstat (limited to 'src/cmd/link/internal/ppc64/asm.go')
| -rw-r--r-- | src/cmd/link/internal/ppc64/asm.go | 1529 |
1 files changed, 1529 insertions, 0 deletions
diff --git a/src/cmd/link/internal/ppc64/asm.go b/src/cmd/link/internal/ppc64/asm.go new file mode 100644 index 0000000..7413599 --- /dev/null +++ b/src/cmd/link/internal/ppc64/asm.go @@ -0,0 +1,1529 @@ +// 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 ppc64 + +import ( + "cmd/internal/objabi" + "cmd/internal/sys" + "cmd/link/internal/ld" + "cmd/link/internal/loader" + "cmd/link/internal/sym" + "debug/elf" + "encoding/binary" + "fmt" + "log" + "strconv" + "strings" +) + +func genpltstub(ctxt *ld.Link, ldr *loader.Loader, r loader.Reloc, s loader.Sym) (sym loader.Sym, firstUse bool) { + // 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. + + // Reserve PLT entry and generate symbol + // resolver + addpltsym(ctxt, ldr, r.Sym()) + + // Generate call stub. Important to note that we're looking + // up the stub using the same version as the parent symbol (s), + // needed so that symtoc() will select the right .TOC. symbol + // when processing the stub. In older versions of the linker + // this was done by setting stub.Outer to the parent, but + // if the stub has the right version initially this is not needed. + n := fmt.Sprintf("%s.%s", ldr.SymName(s), ldr.SymName(r.Sym())) + stub := ldr.CreateSymForUpdate(n, ldr.SymVersion(s)) + firstUse = stub.Size() == 0 + if firstUse { + gencallstub(ctxt, ldr, 1, stub, r.Sym()) + } + + // Update the relocation to use the call stub + r.SetSym(stub.Sym()) + + // Make the symbol writeable so we can fixup toc. + su := ldr.MakeSymbolUpdater(s) + su.MakeWritable() + p := su.Data() + + // Check for toc restore slot (a nop), and replace with toc restore. + var nop uint32 + if len(p) >= int(r.Off()+8) { + nop = ctxt.Arch.ByteOrder.Uint32(p[r.Off()+4:]) + } + if nop != 0x60000000 { + ldr.Errorf(s, "Symbol %s is missing toc restoration slot at offset %d", ldr.SymName(s), r.Off()+4) + } + const o1 = 0xe8410018 // ld r2,24(r1) + ctxt.Arch.ByteOrder.PutUint32(p[r.Off()+4:], o1) + + return stub.Sym(), firstUse +} + +// Scan relocs and generate PLT stubs and generate/fixup ABI defined functions created by the linker. +func genstubs(ctxt *ld.Link, ldr *loader.Loader) { + var stubs []loader.Sym + var abifuncs []loader.Sym + for _, s := range ctxt.Textp { + relocs := ldr.Relocs(s) + for i := 0; i < relocs.Count(); i++ { + r := relocs.At(i) + switch r.Type() { + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_REL24): + switch ldr.SymType(r.Sym()) { + case sym.SDYNIMPORT: + // This call goes through the PLT, generate and call through a PLT stub. + if sym, firstUse := genpltstub(ctxt, ldr, r, s); firstUse { + stubs = append(stubs, sym) + } + + case sym.SXREF: + // Is this an ELF ABI defined function which is (in practice) + // generated by the linker to save/restore callee save registers? + // These are defined similarly for both PPC64 ELF and ELFv2. + targName := ldr.SymName(r.Sym()) + if strings.HasPrefix(targName, "_save") || strings.HasPrefix(targName, "_rest") { + if sym, firstUse := rewriteABIFuncReloc(ctxt, ldr, targName, r); firstUse { + abifuncs = append(abifuncs, sym) + } + } + } + + // Handle objects compiled with -fno-plt. Rewrite local calls to avoid indirect calling. + // These are 0 sized relocs. They mark the mtctr r12, or bctrl + ld r2,24(r1). + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_PLTSEQ): + if ldr.SymType(r.Sym()) == sym.STEXT { + // This should be an mtctr instruction. Turn it into a nop. + su := ldr.MakeSymbolUpdater(s) + const OP_MTCTR = 31<<26 | 0x9<<16 | 467<<1 + const MASK_OP_MTCTR = 63<<26 | 0x3FF<<11 | 0x1FF<<1 + rewritetonop(&ctxt.Target, ldr, su, int64(r.Off()), MASK_OP_MTCTR, OP_MTCTR) + } + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_PLTCALL): + if ldr.SymType(r.Sym()) == sym.STEXT { + // This relocation should point to a bctrl followed by a ld r2, 24(41) + const OP_BL = 0x48000001 // bl 0 + const OP_TOCRESTORE = 0xe8410018 // ld r2,24(r1) + const OP_BCTRL = 0x4e800421 // bctrl + + // Convert the bctrl into a bl. + su := ldr.MakeSymbolUpdater(s) + rewritetoinsn(&ctxt.Target, ldr, su, int64(r.Off()), 0xFFFFFFFF, OP_BCTRL, OP_BL) + + // Turn this reloc into an R_CALLPOWER, and convert the TOC restore into a nop. + su.SetRelocType(i, objabi.R_CALLPOWER) + su.SetRelocAdd(i, r.Add()+int64(ldr.SymLocalentry(r.Sym()))) + r.SetSiz(4) + rewritetonop(&ctxt.Target, ldr, su, int64(r.Off()+4), 0xFFFFFFFF, OP_TOCRESTORE) + } + } + } + } + + // Append any usage of the go versions of ELF save/restore + // functions to the end of the callstub list to minimize + // chances a trampoline might be needed. + stubs = append(stubs, abifuncs...) + + // Put stubs at the beginning (instead of the end). + // So when resolving the relocations to calls to the stubs, + // the addresses are known and trampolines can be inserted + // when necessary. + ctxt.Textp = append(stubs, ctxt.Textp...) +} + +func genaddmoduledata(ctxt *ld.Link, ldr *loader.Loader) { + initfunc, addmoduledata := ld.PrepareAddmoduledata(ctxt) + if initfunc == nil { + return + } + + o := func(op uint32) { + initfunc.AddUint32(ctxt.Arch, op) + } + + // addis r2, r12, .TOC.-func@ha + toc := ctxt.DotTOC[0] + rel1, _ := initfunc.AddRel(objabi.R_ADDRPOWER_PCREL) + rel1.SetOff(0) + rel1.SetSiz(8) + rel1.SetSym(toc) + 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 + var tgt loader.Sym + if s := ldr.Lookup("local.moduledata", 0); s != 0 { + tgt = s + } else if s := ldr.Lookup("local.pluginmoduledata", 0); s != 0 { + tgt = s + } else { + tgt = ldr.LookupOrCreateSym("runtime.firstmoduledata", 0) + } + rel2, _ := initfunc.AddRel(objabi.R_ADDRPOWER_GOT) + rel2.SetOff(int32(initfunc.Size())) + rel2.SetSiz(8) + rel2.SetSym(tgt) + o(0x3c620000) + // ld r3, local.moduledata@got@l(r3) + o(0xe8630000) + // bl runtime.addmoduledata + rel3, _ := initfunc.AddRel(objabi.R_CALLPOWER) + rel3.SetOff(int32(initfunc.Size())) + rel3.SetSiz(4) + rel3.SetSym(addmoduledata) + o(0x48000001) + // nop + o(0x60000000) + // ld r31, 0(r1) + o(0xe8010000) + // mtlr r31 + o(0x7c0803a6) + // addi r1,r1,32 + o(0x38210020) + // blr + o(0x4e800020) +} + +// Rewrite ELF (v1 or v2) calls to _savegpr0_n, _savegpr1_n, _savefpr_n, _restfpr_n, _savevr_m, or +// _restvr_m (14<=n<=31, 20<=m<=31). Redirect them to runtime.elf_restgpr0+(n-14)*4, +// runtime.elf_restvr+(m-20)*8, and similar. +// +// These functions are defined in the ELFv2 ABI (generated when using gcc -Os option) to save and +// restore callee-saved registers (as defined in the PPC64 ELF ABIs) from registers n or m to 31 of +// the named type. R12 and R0 are sometimes used in exceptional ways described in the ABI. +// +// Final note, this is only needed when linking internally. The external linker will generate these +// functions if they are used. +func rewriteABIFuncReloc(ctxt *ld.Link, ldr *loader.Loader, tname string, r loader.Reloc) (sym loader.Sym, firstUse bool) { + s := strings.Split(tname, "_") + // A valid call will split like {"", "savegpr0", "20"} + if len(s) != 3 { + return 0, false // Not an abi func. + } + minReg := 14 // _savegpr0_{n}, _savegpr1_{n}, _savefpr_{n}, 14 <= n <= 31 + offMul := 4 // 1 instruction per register op. + switch s[1] { + case "savegpr0", "savegpr1", "savefpr": + case "restgpr0", "restgpr1", "restfpr": + case "savevr", "restvr": + minReg = 20 // _savevr_{n} or _restvr_{n}, 20 <= n <= 31 + offMul = 8 // 2 instructions per register op. + default: + return 0, false // Not an abi func + } + n, e := strconv.Atoi(s[2]) + if e != nil || n < minReg || n > 31 || r.Add() != 0 { + return 0, false // Invalid register number, or non-zero addend. Not an abi func. + } + + // tname is a valid relocation to an ABI defined register save/restore function. Re-relocate + // them to a go version of these functions in runtime/asm_ppc64x.s + ts := ldr.LookupOrCreateSym("runtime.elf_"+s[1], 0) + r.SetSym(ts) + r.SetAdd(int64((n - minReg) * offMul)) + firstUse = !ldr.AttrReachable(ts) + if firstUse { + ldr.SetAttrReachable(ts, true) + // This function only becomes reachable now. It has been dropped from + // the text section (it was unreachable until now), it needs included. + // + // Similarly, TOC regeneration should not happen for these functions, + // remove it from this save/restore function. + if ldr.AttrShared(ts) { + sb := ldr.MakeSymbolUpdater(ts) + sb.SetData(sb.Data()[8:]) + sb.SetSize(sb.Size() - 8) + relocs := sb.Relocs() + // Only one PCREL reloc to .TOC. should be present. + if relocs.Count() != 1 { + log.Fatalf("Unexpected number of relocs in %s\n", ldr.SymName(ts)) + } + sb.ResetRelocs() + + } + } + return ts, firstUse +} + +func gentext(ctxt *ld.Link, ldr *loader.Loader) { + if ctxt.DynlinkingGo() { + genaddmoduledata(ctxt, ldr) + } + + if ctxt.LinkMode == ld.LinkInternal { + genstubs(ctxt, ldr) + } +} + +// Construct a call stub in stub that calls symbol targ via its PLT +// entry. +func gencallstub(ctxt *ld.Link, ldr *loader.Loader, abicase int, stub *loader.SymbolBuilder, targ loader.Sym) { + if abicase != 1 { + // If we see R_PPC64_TOCSAVE or R_PPC64_REL24_NOTOC + // relocations, we'll need to implement cases 2 and 3. + log.Fatalf("gencallstub only implements case 1 calls") + } + + plt := ctxt.PLT + + stub.SetType(sym.STEXT) + + // Save TOC pointer in TOC save slot + stub.AddUint32(ctxt.Arch, 0xf8410018) // std r2,24(r1) + + // Load the function pointer from the PLT. + rel, ri1 := stub.AddRel(objabi.R_POWER_TOC) + rel.SetOff(int32(stub.Size())) + rel.SetSiz(2) + rel.SetAdd(int64(ldr.SymPlt(targ))) + rel.SetSym(plt) + if ctxt.Arch.ByteOrder == binary.BigEndian { + rel.SetOff(rel.Off() + int32(rel.Siz())) + } + ldr.SetRelocVariant(stub.Sym(), int(ri1), sym.RV_POWER_HA) + stub.AddUint32(ctxt.Arch, 0x3d820000) // addis r12,r2,targ@plt@toc@ha + + rel2, ri2 := stub.AddRel(objabi.R_POWER_TOC) + rel2.SetOff(int32(stub.Size())) + rel2.SetSiz(2) + rel2.SetAdd(int64(ldr.SymPlt(targ))) + rel2.SetSym(plt) + if ctxt.Arch.ByteOrder == binary.BigEndian { + rel2.SetOff(rel2.Off() + int32(rel2.Siz())) + } + ldr.SetRelocVariant(stub.Sym(), int(ri2), sym.RV_POWER_LO) + stub.AddUint32(ctxt.Arch, 0xe98c0000) // ld r12,targ@plt@toc@l(r12) + + // Jump to the loaded pointer + stub.AddUint32(ctxt.Arch, 0x7d8903a6) // mtctr r12 + stub.AddUint32(ctxt.Arch, 0x4e800420) // bctr +} + +// Rewrite the instruction at offset into newinsn. Also, verify the +// existing instruction under mask matches the check value. +func rewritetoinsn(target *ld.Target, ldr *loader.Loader, su *loader.SymbolBuilder, offset int64, mask, check, newinsn uint32) { + su.MakeWritable() + op := target.Arch.ByteOrder.Uint32(su.Data()[offset:]) + if op&mask != check { + ldr.Errorf(su.Sym(), "Rewrite offset 0x%x to 0x%08X failed check (0x%08X&0x%08X != 0x%08X)", offset, newinsn, op, mask, check) + } + su.SetUint32(target.Arch, offset, newinsn) +} + +// Rewrite the instruction at offset into a hardware nop instruction. Also, verify the +// existing instruction under mask matches the check value. +func rewritetonop(target *ld.Target, ldr *loader.Loader, su *loader.SymbolBuilder, offset int64, mask, check uint32) { + const NOP = 0x60000000 + rewritetoinsn(target, ldr, su, offset, mask, check, NOP) +} + +func adddynrel(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym, r loader.Reloc, rIdx int) bool { + if target.IsElf() { + return addelfdynrel(target, ldr, syms, s, r, rIdx) + } else if target.IsAIX() { + return ld.Xcoffadddynrel(target, ldr, syms, s, r, rIdx) + } + return false +} + +func addelfdynrel(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) + } + + 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_PPC64_REL24): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_CALLPOWER) + + // This is a local call, so the caller isn't setting + // up r12 and r2 is the same for the caller and + // callee. Hence, we need to go to the local entry + // point. (If we don't do this, the callee will try + // to use r12 to compute r2.) + su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymLocalentry(targ))) + + if targType == sym.SDYNIMPORT { + // Should have been handled in elfsetupplt + ldr.Errorf(s, "unexpected R_PPC64_REL24 for dyn import") + } + + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC_REL32): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_PCREL) + su.SetRelocAdd(rIdx, r.Add()+4) + + if targType == sym.SDYNIMPORT { + ldr.Errorf(s, "unexpected R_PPC_REL32 for dyn import") + } + + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_ADDR64): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_ADDR) + if targType == sym.SDYNIMPORT { + // These happen in .toc sections + ld.Adddynsym(ldr, target, syms, targ) + + rela := ldr.MakeSymbolUpdater(syms.Rela) + rela.AddAddrPlus(target.Arch, s, int64(r.Off())) + rela.AddUint64(target.Arch, elf.R_INFO(uint32(ldr.SymDynid(targ)), uint32(elf.R_PPC64_ADDR64))) + rela.AddUint64(target.Arch, uint64(r.Add())) + su.SetRelocType(rIdx, objabi.ElfRelocOffset) // ignore during relocsym + } else 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_PPC64_TOC16): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_POWER_TOC) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_LO|sym.RV_CHECK_OVERFLOW) + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_TOC16_LO): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_POWER_TOC) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_LO) + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_TOC16_HA): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_POWER_TOC) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_HA|sym.RV_CHECK_OVERFLOW) + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_TOC16_HI): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_POWER_TOC) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_HI|sym.RV_CHECK_OVERFLOW) + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_TOC16_DS): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_POWER_TOC) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_DS|sym.RV_CHECK_OVERFLOW) + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_TOC16_LO_DS): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_POWER_TOC) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_DS) + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_REL16_LO): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_PCREL) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_LO) + su.SetRelocAdd(rIdx, r.Add()+2) // Compensate for relocation size of 2 + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_REL16_HI): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_PCREL) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_HI|sym.RV_CHECK_OVERFLOW) + su.SetRelocAdd(rIdx, r.Add()+2) + return true + + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_REL16_HA): + su := ldr.MakeSymbolUpdater(s) + su.SetRelocType(rIdx, objabi.R_PCREL) + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_HA|sym.RV_CHECK_OVERFLOW) + su.SetRelocAdd(rIdx, r.Add()+2) + return true + + // When compiling with gcc's -fno-plt option (no PLT), the following code and relocation + // sequences may be present to call an external function: + // + // 1. addis Rx,foo@R_PPC64_PLT16_HA + // 2. ld 12,foo@R_PPC64_PLT16_LO_DS(Rx) + // 3. mtctr 12 ; foo@R_PPC64_PLTSEQ + // 4. bctrl ; foo@R_PPC64_PLTCALL + // 5. ld r2,24(r1) + // + // Note, 5 is required to follow the R_PPC64_PLTCALL. Similarly, relocations targeting + // instructions 3 and 4 are zero sized informational relocations. + case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_PLT16_HA), + objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_PLT16_LO_DS): + su := ldr.MakeSymbolUpdater(s) + isPLT16_LO_DS := r.Type() == objabi.ElfRelocOffset+objabi.RelocType(elf.R_PPC64_PLT16_LO_DS) + if isPLT16_LO_DS { + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_DS) + } else { + ldr.SetRelocVariant(s, rIdx, sym.RV_POWER_HA|sym.RV_CHECK_OVERFLOW) + } + su.SetRelocType(rIdx, objabi.R_POWER_TOC) + if targType == sym.SDYNIMPORT { + // This is an external symbol, make space in the GOT and retarget the reloc. + ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_PPC64_GLOB_DAT)) + su.SetRelocSym(rIdx, syms.GOT) + su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ))) + } else if targType == sym.STEXT { + if isPLT16_LO_DS { + // Expect an ld opcode to nop + const MASK_OP_LD = 63<<26 | 0x3 + const OP_LD = 58 << 26 + rewritetonop(target, ldr, su, int64(r.Off()), MASK_OP_LD, OP_LD) + } else { + // Expect an addis opcode to nop + const MASK_OP_ADDIS = 63 << 26 + const OP_ADDIS = 15 << 26 + rewritetonop(target, ldr, su, int64(r.Off()), MASK_OP_ADDIS, OP_ADDIS) + } + // And we can ignore this reloc now. + su.SetRelocType(rIdx, objabi.ElfRelocOffset) + } else { + ldr.Errorf(s, "unexpected PLT relocation target symbol type %s", targType.String()) + } + return true + } + + // Handle references to ELF symbols from our own object files. + relocs := ldr.Relocs(s) + r = relocs.At(rIdx) + + switch r.Type() { + case objabi.R_ADDR: + if ldr.SymType(s) == sym.STEXT { + log.Fatalf("R_ADDR relocation in text symbol %s is unsupported\n", ldr.SymName(s)) + } + 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 ldr.SymType(s) != sym.SDATA && ldr.SymType(s) != sym.SRODATA { + break + } + } + // Generate R_PPC64_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_PPC64_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_PPC64_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 + } + + return false +} + +func xcoffreloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool { + rs := r.Xsym + + emitReloc := func(v uint16, off uint64) { + out.Write64(uint64(sectoff) + off) + out.Write32(uint32(ldr.SymDynid(rs))) + out.Write16(v) + } + + var v uint16 + switch r.Type { + default: + return false + case objabi.R_ADDR, objabi.R_DWARFSECREF: + v = ld.XCOFF_R_POS + if r.Size == 4 { + v |= 0x1F << 8 + } else { + v |= 0x3F << 8 + } + emitReloc(v, 0) + case objabi.R_ADDRPOWER_TOCREL: + case objabi.R_ADDRPOWER_TOCREL_DS: + emitReloc(ld.XCOFF_R_TOCU|(0x0F<<8), 2) + emitReloc(ld.XCOFF_R_TOCL|(0x0F<<8), 6) + case objabi.R_POWER_TLS_LE: + // This only supports 16b relocations. It is fixed up in archreloc. + emitReloc(ld.XCOFF_R_TLS_LE|0x0F<<8, 2) + case objabi.R_CALLPOWER: + if r.Size != 4 { + return false + } + emitReloc(ld.XCOFF_R_RBR|0x19<<8, 0) + case objabi.R_XCOFFREF: + emitReloc(ld.XCOFF_R_REF|0x3F<<8, 0) + } + return true + +} + +func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, ri int, sectoff int64) bool { + // Beware that bit0~bit15 start from the third byte of a instruction in Big-Endian machines. + rt := r.Type + if rt == objabi.R_ADDR || rt == objabi.R_POWER_TLS || rt == objabi.R_CALLPOWER { + } else { + if ctxt.Arch.ByteOrder == binary.BigEndian { + sectoff += 2 + } + } + out.Write64(uint64(sectoff)) + + elfsym := ld.ElfSymForReloc(ctxt, r.Xsym) + switch rt { + default: + return false + case objabi.R_ADDR, objabi.R_DWARFSECREF: + switch r.Size { + case 4: + out.Write64(uint64(elf.R_PPC64_ADDR32) | uint64(elfsym)<<32) + case 8: + out.Write64(uint64(elf.R_PPC64_ADDR64) | uint64(elfsym)<<32) + default: + return false + } + case objabi.R_ADDRPOWER_D34: + out.Write64(uint64(elf.R_PPC64_D34) | uint64(elfsym)<<32) + case objabi.R_ADDRPOWER_PCREL34: + out.Write64(uint64(elf.R_PPC64_PCREL34) | uint64(elfsym)<<32) + case objabi.R_POWER_TLS: + out.Write64(uint64(elf.R_PPC64_TLS) | uint64(elfsym)<<32) + case objabi.R_POWER_TLS_LE: + out.Write64(uint64(elf.R_PPC64_TPREL16_HA) | uint64(elfsym)<<32) + out.Write64(uint64(r.Xadd)) + out.Write64(uint64(sectoff + 4)) + out.Write64(uint64(elf.R_PPC64_TPREL16_LO) | uint64(elfsym)<<32) + case objabi.R_POWER_TLS_LE_TPREL34: + out.Write64(uint64(elf.R_PPC64_TPREL34) | uint64(elfsym)<<32) + case objabi.R_POWER_TLS_IE_PCREL34: + out.Write64(uint64(elf.R_PPC64_GOT_TPREL_PCREL34) | uint64(elfsym)<<32) + case objabi.R_POWER_TLS_IE: + out.Write64(uint64(elf.R_PPC64_GOT_TPREL16_HA) | uint64(elfsym)<<32) + out.Write64(uint64(r.Xadd)) + out.Write64(uint64(sectoff + 4)) + out.Write64(uint64(elf.R_PPC64_GOT_TPREL16_LO_DS) | uint64(elfsym)<<32) + case objabi.R_ADDRPOWER: + out.Write64(uint64(elf.R_PPC64_ADDR16_HA) | uint64(elfsym)<<32) + out.Write64(uint64(r.Xadd)) + out.Write64(uint64(sectoff + 4)) + out.Write64(uint64(elf.R_PPC64_ADDR16_LO) | uint64(elfsym)<<32) + case objabi.R_ADDRPOWER_DS: + out.Write64(uint64(elf.R_PPC64_ADDR16_HA) | uint64(elfsym)<<32) + out.Write64(uint64(r.Xadd)) + out.Write64(uint64(sectoff + 4)) + out.Write64(uint64(elf.R_PPC64_ADDR16_LO_DS) | uint64(elfsym)<<32) + case objabi.R_ADDRPOWER_GOT: + out.Write64(uint64(elf.R_PPC64_GOT16_HA) | uint64(elfsym)<<32) + out.Write64(uint64(r.Xadd)) + out.Write64(uint64(sectoff + 4)) + out.Write64(uint64(elf.R_PPC64_GOT16_LO_DS) | uint64(elfsym)<<32) + case objabi.R_ADDRPOWER_PCREL: + out.Write64(uint64(elf.R_PPC64_REL16_HA) | uint64(elfsym)<<32) + out.Write64(uint64(r.Xadd)) + out.Write64(uint64(sectoff + 4)) + out.Write64(uint64(elf.R_PPC64_REL16_LO) | uint64(elfsym)<<32) + r.Xadd += 4 + case objabi.R_ADDRPOWER_TOCREL: + out.Write64(uint64(elf.R_PPC64_TOC16_HA) | uint64(elfsym)<<32) + out.Write64(uint64(r.Xadd)) + out.Write64(uint64(sectoff + 4)) + out.Write64(uint64(elf.R_PPC64_TOC16_LO) | uint64(elfsym)<<32) + case objabi.R_ADDRPOWER_TOCREL_DS: + out.Write64(uint64(elf.R_PPC64_TOC16_HA) | uint64(elfsym)<<32) + out.Write64(uint64(r.Xadd)) + out.Write64(uint64(sectoff + 4)) + out.Write64(uint64(elf.R_PPC64_TOC16_LO_DS) | uint64(elfsym)<<32) + case objabi.R_CALLPOWER: + if r.Size != 4 { + return false + } + out.Write64(uint64(elf.R_PPC64_REL24) | uint64(elfsym)<<32) + + } + out.Write64(uint64(r.Xadd)) + + return true +} + +func elfsetupplt(ctxt *ld.Link, plt, got *loader.SymbolBuilder, dynamic loader.Sym) { + if plt.Size() == 0 { + // The dynamic linker stores the address of the + // dynamic resolver and the DSO identifier in the two + // doublewords at the beginning of the .plt section + // before the PLT array. Reserve space for these. + plt.SetSize(16) + } +} + +func machoreloc1(*sys.Arch, *ld.OutBuf, *loader.Loader, loader.Sym, loader.ExtReloc, int64) bool { + return false +} + +// Return the value of .TOC. for symbol s +func symtoc(ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym) int64 { + v := ldr.SymVersion(s) + if out := ldr.OuterSym(s); out != 0 { + v = ldr.SymVersion(out) + } + + toc := syms.DotTOC[v] + if toc == 0 { + ldr.Errorf(s, "TOC-relative relocation in object without .TOC.") + return 0 + } + + return ldr.SymValue(toc) +} + +// archreloctoc relocates a TOC relative symbol. +func archreloctoc(ldr *loader.Loader, target *ld.Target, syms *ld.ArchSyms, r loader.Reloc, s loader.Sym, val int64) int64 { + rs := r.Sym() + var o1, o2 uint32 + var t int64 + useAddi := false + + if target.IsBigEndian() { + o1 = uint32(val >> 32) + o2 = uint32(val) + } else { + o1 = uint32(val) + o2 = uint32(val >> 32) + } + + // On AIX, TOC data accesses are always made indirectly against R2 (a sequence of addis+ld+load/store). If the + // The target of the load is known, the sequence can be written into addis+addi+load/store. On Linux, + // TOC data accesses are always made directly against R2 (e.g addis+load/store). + if target.IsAIX() { + if !strings.HasPrefix(ldr.SymName(rs), "TOC.") { + ldr.Errorf(s, "archreloctoc called for a symbol without TOC anchor") + } + relocs := ldr.Relocs(rs) + tarSym := relocs.At(0).Sym() + + if target.IsInternal() && tarSym != 0 && ldr.AttrReachable(tarSym) && ldr.SymSect(tarSym).Seg == &ld.Segdata { + t = ldr.SymValue(tarSym) + r.Add() - ldr.SymValue(syms.TOC) + // change ld to addi in the second instruction + o2 = (o2 & 0x03FF0000) | 0xE<<26 + useAddi = true + } else { + t = ldr.SymValue(rs) + r.Add() - ldr.SymValue(syms.TOC) + } + } else { + t = ldr.SymValue(rs) + r.Add() - symtoc(ldr, syms, s) + } + + if t != int64(int32(t)) { + ldr.Errorf(s, "TOC relocation for %s is too big to relocate %s: 0x%x", ldr.SymName(s), rs, t) + } + + if t&0x8000 != 0 { + t += 0x10000 + } + + o1 |= uint32((t >> 16) & 0xFFFF) + + switch r.Type() { + case objabi.R_ADDRPOWER_TOCREL_DS: + if useAddi { + o2 |= uint32(t) & 0xFFFF + } else { + if t&3 != 0 { + ldr.Errorf(s, "bad DS reloc for %s: %d", ldr.SymName(s), ldr.SymValue(rs)) + } + o2 |= uint32(t) & 0xFFFC + } + case objabi.R_ADDRPOWER_TOCREL: + o2 |= uint32(t) & 0xffff + default: + return -1 + } + + if target.IsBigEndian() { + return int64(o1)<<32 | int64(o2) + } + return int64(o2)<<32 | int64(o1) +} + +// archrelocaddr relocates a symbol address. +// This code is for linux only. +func archrelocaddr(ldr *loader.Loader, target *ld.Target, syms *ld.ArchSyms, r loader.Reloc, s loader.Sym, val int64) int64 { + rs := r.Sym() + if target.IsAIX() { + ldr.Errorf(s, "archrelocaddr called for %s relocation\n", ldr.SymName(rs)) + } + o1, o2 := unpackInstPair(target, val) + + // Verify resulting address fits within a 31 bit (2GB) address space. + // This is a restriction arising from the usage of lis (HA) + d-form + // (LO) instruction sequences used to implement absolute relocations + // on PPC64 prior to ISA 3.1 (P10). For consistency, maintain this + // restriction for ISA 3.1 unless it becomes problematic. + t := ldr.SymAddr(rs) + r.Add() + if t < 0 || t >= 1<<31 { + ldr.Errorf(s, "relocation for %s is too big (>=2G): 0x%x", ldr.SymName(s), ldr.SymValue(rs)) + } + + switch r.Type() { + case objabi.R_ADDRPOWER_PCREL34: + // S + A - P + t -= (ldr.SymValue(s) + int64(r.Off())) + o1 |= computePrefix34HI(t) + o2 |= computeLO(int32(t)) + case objabi.R_ADDRPOWER_D34: + o1 |= computePrefix34HI(t) + o2 |= computeLO(int32(t)) + case objabi.R_ADDRPOWER: + o1 |= computeHA(int32(t)) + o2 |= computeLO(int32(t)) + case objabi.R_ADDRPOWER_DS: + o1 |= computeHA(int32(t)) + o2 |= computeLO(int32(t)) + if t&3 != 0 { + ldr.Errorf(s, "bad DS reloc for %s: %d", ldr.SymName(s), ldr.SymValue(rs)) + } + default: + return -1 + } + + return packInstPair(target, o1, o2) +} + +// Determine if the code was compiled so that the TOC register R2 is initialized and maintained. +func r2Valid(ctxt *ld.Link) bool { + switch ctxt.BuildMode { + case ld.BuildModeCArchive, ld.BuildModeCShared, ld.BuildModePIE, ld.BuildModeShared, ld.BuildModePlugin: + return true + } + // -linkshared option + return ctxt.IsSharedGoLink() +} + +// resolve direct jump relocation r in s, and add trampoline if necessary. +func trampoline(ctxt *ld.Link, ldr *loader.Loader, ri int, rs, s loader.Sym) { + + // Trampolines are created if the branch offset is too large and the linker cannot insert a call stub to handle it. + // For internal linking, trampolines are always created for long calls. + // For external linking, the linker can insert a call stub to handle a long call, but depends on having the TOC address in + // r2. For those build modes with external linking where the TOC address is not maintained in r2, trampolines must be created. + if ctxt.IsExternal() && r2Valid(ctxt) { + // The TOC pointer is valid. The external linker will insert trampolines. + return + } + + relocs := ldr.Relocs(s) + r := relocs.At(ri) + 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())) + } + switch r.Type() { + case objabi.R_CALLPOWER: + + // If branch offset is too far then create a trampoline. + + if (ctxt.IsExternal() && ldr.SymSect(s) != ldr.SymSect(rs)) || (ctxt.IsInternal() && int64(int32(t<<6)>>6) != t) || ldr.SymValue(rs) == 0 || (*ld.FlagDebugTramp > 1 && ldr.SymPkg(s) != ldr.SymPkg(rs)) { + var tramp loader.Sym + for i := 0; ; i++ { + + // Using r.Add as part of the name is significant in functions like duffzero where the call + // target is at some offset within the function. Calls to duff+8 and duff+256 must appear as + // distinct trampolines. + + oName := ldr.SymName(rs) + name := oName + if r.Add() == 0 { + name += fmt.Sprintf("-tramp%d", i) + } else { + name += fmt.Sprintf("%+x-tramp%d", r.Add(), i) + } + + // Look up the trampoline in case it already exists + + tramp = ldr.LookupOrCreateSym(name, int(ldr.SymVersion(rs))) + if oName == "runtime.deferreturn" { + ldr.SetIsDeferReturnTramp(tramp, true) + } + if ldr.SymValue(tramp) == 0 { + break + } + // Note, the trampoline is always called directly. The addend of the original relocation is accounted for in the + // trampoline itself. + t = ldr.SymValue(tramp) - (ldr.SymValue(s) + int64(r.Off())) + + // With internal linking, the trampoline can be used if it is not too far. + // With external linking, the trampoline must be in this section for it to be reused. + if (ctxt.IsInternal() && int64(int32(t<<6)>>6) == t) || (ctxt.IsExternal() && ldr.SymSect(s) == ldr.SymSect(tramp)) { + break + } + } + if ldr.SymType(tramp) == 0 { + trampb := ldr.MakeSymbolUpdater(tramp) + ctxt.AddTramp(trampb) + gentramp(ctxt, ldr, trampb, rs, r.Add()) + } + sb := ldr.MakeSymbolUpdater(s) + relocs := sb.Relocs() + r := relocs.At(ri) + r.SetSym(tramp) + r.SetAdd(0) // This was folded into the trampoline target address + } + default: + ctxt.Errorf(s, "trampoline called with non-jump reloc: %d (%s)", r.Type(), sym.RelocName(ctxt.Arch, r.Type())) + } +} + +func gentramp(ctxt *ld.Link, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) { + tramp.SetSize(16) // 4 instructions + P := make([]byte, tramp.Size()) + var o1, o2 uint32 + + if ctxt.IsAIX() { + // On AIX, the address is retrieved with a TOC symbol. + // For internal linking, the "Linux" way might still be used. + // However, all text symbols are accessed with a TOC symbol as + // text relocations aren't supposed to be possible. + // So, keep using the external linking way to be more AIX friendly. + o1 = uint32(0x3c000000) | 12<<21 | 2<<16 // addis r12, r2, toctargetaddr hi + o2 = uint32(0xe8000000) | 12<<21 | 12<<16 // ld r12, r12, toctargetaddr lo + + toctramp := ldr.CreateSymForUpdate("TOC."+ldr.SymName(tramp.Sym()), 0) + toctramp.SetType(sym.SXCOFFTOC) + toctramp.AddAddrPlus(ctxt.Arch, target, offset) + + r, _ := tramp.AddRel(objabi.R_ADDRPOWER_TOCREL_DS) + r.SetOff(0) + r.SetSiz(8) // generates 2 relocations: HA + LO + r.SetSym(toctramp.Sym()) + } else { + // Used for default build mode for an executable + // Address of the call target is generated using + // relocation and doesn't depend on r2 (TOC). + o1 = uint32(0x3c000000) | 12<<21 // lis r12,targetaddr hi + o2 = uint32(0x38000000) | 12<<21 | 12<<16 // addi r12,r12,targetaddr lo + + // ELFv2 save/restore functions use R0/R12 in special ways, therefore trampolines + // as generated here will not always work correctly. + if strings.HasPrefix(ldr.SymName(target), "runtime.elf_") { + log.Fatalf("Internal linker does not support trampolines to ELFv2 ABI"+ + " register save/restore function %s", ldr.SymName(target)) + } + + t := ldr.SymValue(target) + if t == 0 || r2Valid(ctxt) || ctxt.IsExternal() { + // Target address is unknown, generate relocations + r, _ := tramp.AddRel(objabi.R_ADDRPOWER) + if r2Valid(ctxt) { + // Use a TOC relative address if R2 holds the TOC pointer + o1 |= uint32(2 << 16) // Transform lis r31,ha into addis r31,r2,ha + r.SetType(objabi.R_ADDRPOWER_TOCREL) + } + r.SetOff(0) + r.SetSiz(8) // generates 2 relocations: HA + LO + r.SetSym(target) + r.SetAdd(offset) + } else { + // The target address is known, resolve it + t += offset + o1 |= (uint32(t) + 0x8000) >> 16 // HA + o2 |= uint32(t) & 0xFFFF // LO + } + } + + o3 := uint32(0x7c0903a6) | 12<<21 // mtctr r12 + o4 := uint32(0x4e800420) // bctr + ctxt.Arch.ByteOrder.PutUint32(P, o1) + ctxt.Arch.ByteOrder.PutUint32(P[4:], o2) + ctxt.Arch.ByteOrder.PutUint32(P[8:], o3) + ctxt.Arch.ByteOrder.PutUint32(P[12:], o4) + tramp.SetData(P) +} + +// Unpack a pair of 32 bit instruction words from +// a 64 bit relocation into instN and instN+1 in endian order. +func unpackInstPair(target *ld.Target, r int64) (uint32, uint32) { + if target.IsBigEndian() { + return uint32(r >> 32), uint32(r) + } + return uint32(r), uint32(r >> 32) +} + +// Pack a pair of 32 bit instruction words o1, o2 into 64 bit relocation +// in endian order. +func packInstPair(target *ld.Target, o1, o2 uint32) int64 { + if target.IsBigEndian() { + return (int64(o1) << 32) | int64(o2) + } + return int64(o1) | (int64(o2) << 32) +} + +// Compute the high-adjusted value (always a signed 32b value) per the ELF ABI. +// The returned value is always 0 <= x <= 0xFFFF. +func computeHA(val int32) uint32 { + return uint32(uint16((val + 0x8000) >> 16)) +} + +// Compute the low value (the lower 16 bits of any 32b value) per the ELF ABI. +// The returned value is always 0 <= x <= 0xFFFF. +func computeLO(val int32) uint32 { + return uint32(uint16(val)) +} + +// Compute the high 18 bits of a signed 34b constant. Used to pack the high 18 bits +// of a prefix34 relocation field. This assumes the input is already restricted to +// 34 bits. +func computePrefix34HI(val int64) uint32 { + return uint32((val >> 16) & 0x3FFFF) +} + +func computeTLSLEReloc(target *ld.Target, ldr *loader.Loader, rs, s loader.Sym) int64 { + // The thread pointer points 0x7000 bytes after the start of the + // thread local storage area as documented in section "3.7.2 TLS + // Runtime Handling" of "Power Architecture 64-Bit ELF V2 ABI + // Specification". + v := ldr.SymValue(rs) - 0x7000 + if target.IsAIX() { + // On AIX, the thread pointer points 0x7800 bytes after + // the TLS. + v -= 0x800 + } + + if int64(int32(v)) != v { + ldr.Errorf(s, "TLS offset out of range %d", v) + } + return v +} + +func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loader.Reloc, s loader.Sym, val int64) (relocatedOffset int64, nExtReloc int, ok bool) { + rs := r.Sym() + if target.IsExternal() { + // On AIX, relocations (except TLS ones) must be also done to the + // value with the current addresses. + switch rt := r.Type(); rt { + default: + if !target.IsAIX() { + return val, nExtReloc, false + } + case objabi.R_POWER_TLS, objabi.R_POWER_TLS_IE_PCREL34, objabi.R_POWER_TLS_LE_TPREL34: + nExtReloc = 1 + return val, nExtReloc, true + case objabi.R_POWER_TLS_LE, objabi.R_POWER_TLS_IE: + if target.IsAIX() && rt == objabi.R_POWER_TLS_LE { + // Fixup val, an addis/addi pair of instructions, which generate a 32b displacement + // from the threadpointer (R13), into a 16b relocation. XCOFF only supports 16b + // TLS LE relocations. Likewise, verify this is an addis/addi sequence. + const expectedOpcodes = 0x3C00000038000000 + const expectedOpmasks = 0xFC000000FC000000 + if uint64(val)&expectedOpmasks != expectedOpcodes { + ldr.Errorf(s, "relocation for %s+%d is not an addis/addi pair: %16x", ldr.SymName(rs), r.Off(), uint64(val)) + } + nval := (int64(uint32(0x380d0000)) | val&0x03e00000) << 32 // addi rX, r13, $0 + nval |= int64(0x60000000) // nop + val = nval + nExtReloc = 1 + } else { + nExtReloc = 2 + } + return val, nExtReloc, true + case objabi.R_ADDRPOWER, + objabi.R_ADDRPOWER_DS, + objabi.R_ADDRPOWER_TOCREL, + objabi.R_ADDRPOWER_TOCREL_DS, + objabi.R_ADDRPOWER_GOT, + objabi.R_ADDRPOWER_PCREL: + nExtReloc = 2 // need two ELF relocations, see elfreloc1 + if !target.IsAIX() { + return val, nExtReloc, true + } + case objabi.R_CALLPOWER, objabi.R_ADDRPOWER_D34, objabi.R_ADDRPOWER_PCREL34: + nExtReloc = 1 + if !target.IsAIX() { + return val, nExtReloc, true + } + } + } + + switch r.Type() { + case objabi.R_ADDRPOWER_TOCREL, objabi.R_ADDRPOWER_TOCREL_DS: + return archreloctoc(ldr, target, syms, r, s, val), nExtReloc, true + case objabi.R_ADDRPOWER, objabi.R_ADDRPOWER_DS, objabi.R_ADDRPOWER_D34, objabi.R_ADDRPOWER_PCREL34: + return archrelocaddr(ldr, target, syms, r, s, val), nExtReloc, true + case objabi.R_CALLPOWER: + // Bits 6 through 29 = (S + A - P) >> 2 + + t := ldr.SymValue(rs) + r.Add() - (ldr.SymValue(s) + int64(r.Off())) + + tgtName := ldr.SymName(rs) + + // If we are linking PIE or shared code, all golang generated object files have an extra 2 instruction prologue + // to regenerate the TOC pointer from R12. The exception are two special case functions tested below. Note, + // local call offsets for externally generated objects are accounted for when converting into golang relocs. + if !ldr.AttrExternal(rs) && ldr.AttrShared(rs) && tgtName != "runtime.duffzero" && tgtName != "runtime.duffcopy" { + // Furthermore, only apply the offset if the target looks like the start of a function call. + if r.Add() == 0 && ldr.SymType(rs) == sym.STEXT { + t += 8 + } + } + + if t&3 != 0 { + ldr.Errorf(s, "relocation for %s+%d is not aligned: %d", ldr.SymName(rs), r.Off(), t) + } + // If branch offset is too far then create a trampoline. + + if int64(int32(t<<6)>>6) != t { + ldr.Errorf(s, "direct call too far: %s %x", ldr.SymName(rs), t) + } + return val | int64(uint32(t)&^0xfc000003), nExtReloc, true + case objabi.R_POWER_TOC: // S + A - .TOC. + return ldr.SymValue(rs) + r.Add() - symtoc(ldr, syms, s), nExtReloc, true + + case objabi.R_ADDRPOWER_PCREL: // S + A - P + t := ldr.SymValue(rs) + r.Add() - (ldr.SymValue(s) + int64(r.Off())) + ha, l := unpackInstPair(target, val) + l |= computeLO(int32(t)) + ha |= computeHA(int32(t)) + return packInstPair(target, ha, l), nExtReloc, true + + case objabi.R_POWER_TLS: + const OP_ADD = 31<<26 | 266<<1 + const MASK_OP_ADD = 0x3F<<26 | 0x1FF<<1 + if val&MASK_OP_ADD != OP_ADD { + ldr.Errorf(s, "R_POWER_TLS reloc only supports XO form ADD, not %08X", val) + } + // Verify RB is R13 in ADD RA,RB,RT. + if (val>>11)&0x1F != 13 { + // If external linking is made to support this, it may expect the linker to rewrite RB. + ldr.Errorf(s, "R_POWER_TLS reloc requires R13 in RB (%08X).", uint32(val)) + } + return val, nExtReloc, true + + case objabi.R_POWER_TLS_IE: + // Convert TLS_IE relocation to TLS_LE if supported. + if !(target.IsPIE() && target.IsElf()) { + log.Fatalf("cannot handle R_POWER_TLS_IE (sym %s) when linking non-PIE, non-ELF binaries internally", ldr.SymName(s)) + } + + // We are an ELF binary, we can safely convert to TLS_LE from: + // addis to, r2, x@got@tprel@ha + // ld to, to, x@got@tprel@l(to) + // + // to TLS_LE by converting to: + // addis to, r0, x@tprel@ha + // addi to, to, x@tprel@l(to) + + const OP_ADDI = 14 << 26 + const OP_MASK = 0x3F << 26 + const OP_RA_MASK = 0x1F << 16 + // convert r2 to r0, and ld to addi + mask := packInstPair(target, OP_RA_MASK, OP_MASK) + addi_op := packInstPair(target, 0, OP_ADDI) + val &^= mask + val |= addi_op + fallthrough + + case objabi.R_POWER_TLS_LE: + v := computeTLSLEReloc(target, ldr, rs, s) + o1, o2 := unpackInstPair(target, val) + o1 |= computeHA(int32(v)) + o2 |= computeLO(int32(v)) + return packInstPair(target, o1, o2), nExtReloc, true + + case objabi.R_POWER_TLS_IE_PCREL34: + // Convert TLS_IE relocation to TLS_LE if supported. + if !(target.IsPIE() && target.IsElf()) { + log.Fatalf("cannot handle R_POWER_TLS_IE (sym %s) when linking non-PIE, non-ELF binaries internally", ldr.SymName(s)) + } + + // We are an ELF binary, we can safely convert to TLS_LE_TPREL34 from: + // pld rX, x@got@tprel@pcrel + // + // to TLS_LE_TPREL32 by converting to: + // pla rX, x@tprel + + const OP_MASK_PFX = 0xFFFFFFFF // Discard prefix word + const OP_MASK = (0x3F << 26) | 0xFFFF // Preserve RT, RA + const OP_PFX = 1<<26 | 2<<24 + const OP_PLA = 14 << 26 + mask := packInstPair(target, OP_MASK_PFX, OP_MASK) + pla_op := packInstPair(target, OP_PFX, OP_PLA) + val &^= mask + val |= pla_op + fallthrough + + case objabi.R_POWER_TLS_LE_TPREL34: + v := computeTLSLEReloc(target, ldr, rs, s) + o1, o2 := unpackInstPair(target, val) + o1 |= computePrefix34HI(v) + o2 |= computeLO(int32(v)) + return packInstPair(target, o1, o2), nExtReloc, true + } + + return val, nExtReloc, false +} + +func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv sym.RelocVariant, s loader.Sym, t int64, p []byte) (relocatedOffset int64) { + rs := r.Sym() + switch rv & sym.RV_TYPE_MASK { + default: + ldr.Errorf(s, "unexpected relocation variant %d", rv) + fallthrough + + case sym.RV_NONE: + return t + + case sym.RV_POWER_LO: + if rv&sym.RV_CHECK_OVERFLOW != 0 { + // Whether to check for signed or unsigned + // overflow depends on the instruction + var o1 uint32 + if target.IsBigEndian() { + o1 = binary.BigEndian.Uint32(p[r.Off()-2:]) + + } else { + o1 = binary.LittleEndian.Uint32(p[r.Off():]) + } + switch o1 >> 26 { + case 24, // ori + 26, // xori + 28: // andi + if t>>16 != 0 { + goto overflow + } + + default: + if int64(int16(t)) != t { + goto overflow + } + } + } + + return int64(int16(t)) + + case sym.RV_POWER_HA: + t += 0x8000 + fallthrough + + // Fallthrough + case sym.RV_POWER_HI: + t >>= 16 + + if rv&sym.RV_CHECK_OVERFLOW != 0 { + // Whether to check for signed or unsigned + // overflow depends on the instruction + var o1 uint32 + if target.IsBigEndian() { + o1 = binary.BigEndian.Uint32(p[r.Off()-2:]) + } else { + o1 = binary.LittleEndian.Uint32(p[r.Off():]) + } + switch o1 >> 26 { + case 25, // oris + 27, // xoris + 29: // andis + if t>>16 != 0 { + goto overflow + } + + default: + if int64(int16(t)) != t { + goto overflow + } + } + } + + return int64(int16(t)) + + case sym.RV_POWER_DS: + var o1 uint32 + if target.IsBigEndian() { + o1 = uint32(binary.BigEndian.Uint16(p[r.Off():])) + } else { + o1 = uint32(binary.LittleEndian.Uint16(p[r.Off():])) + } + if t&3 != 0 { + ldr.Errorf(s, "relocation for %s+%d is not aligned: %d", ldr.SymName(rs), r.Off(), t) + } + if (rv&sym.RV_CHECK_OVERFLOW != 0) && int64(int16(t)) != t { + goto overflow + } + return int64(o1)&0x3 | int64(int16(t)) + } + +overflow: + ldr.Errorf(s, "relocation for %s+%d is too big: %d", ldr.SymName(rs), r.Off(), t) + return t +} + +func extreloc(target *ld.Target, ldr *loader.Loader, r loader.Reloc, s loader.Sym) (loader.ExtReloc, bool) { + switch r.Type() { + case objabi.R_POWER_TLS, objabi.R_POWER_TLS_LE, objabi.R_POWER_TLS_IE, objabi.R_POWER_TLS_IE_PCREL34, objabi.R_POWER_TLS_LE_TPREL34, objabi.R_CALLPOWER: + return ld.ExtrelocSimple(ldr, r), true + case objabi.R_ADDRPOWER, + objabi.R_ADDRPOWER_DS, + objabi.R_ADDRPOWER_TOCREL, + objabi.R_ADDRPOWER_TOCREL_DS, + objabi.R_ADDRPOWER_GOT, + objabi.R_ADDRPOWER_PCREL, + objabi.R_ADDRPOWER_D34, + objabi.R_ADDRPOWER_PCREL34: + return ld.ExtrelocViaOuterSym(ldr, r, s), true + } + return loader.ExtReloc{}, false +} + +func addpltsym(ctxt *ld.Link, ldr *loader.Loader, s loader.Sym) { + if ldr.SymPlt(s) >= 0 { + return + } + + ld.Adddynsym(ldr, &ctxt.Target, &ctxt.ArchSyms, s) + + if ctxt.IsELF { + plt := ldr.MakeSymbolUpdater(ctxt.PLT) + rela := ldr.MakeSymbolUpdater(ctxt.RelaPLT) + if plt.Size() == 0 { + panic("plt is not set up") + } + + // Create the glink resolver if necessary + glink := ensureglinkresolver(ctxt, ldr) + + // Write symbol resolver stub (just a branch to the + // glink resolver stub) + rel, _ := glink.AddRel(objabi.R_CALLPOWER) + rel.SetOff(int32(glink.Size())) + rel.SetSiz(4) + rel.SetSym(glink.Sym()) + glink.AddUint32(ctxt.Arch, 0x48000000) // b .glink + + // In the ppc64 ABI, the dynamic linker is responsible + // for writing the entire PLT. We just need to + // reserve 8 bytes for each PLT entry and generate a + // JMP_SLOT dynamic relocation for it. + // + // TODO(austin): ABI v1 is different + ldr.SetPlt(s, int32(plt.Size())) + + plt.Grow(plt.Size() + 8) + plt.SetSize(plt.Size() + 8) + + rela.AddAddrPlus(ctxt.Arch, plt.Sym(), int64(ldr.SymPlt(s))) + rela.AddUint64(ctxt.Arch, elf.R_INFO(uint32(ldr.SymDynid(s)), uint32(elf.R_PPC64_JMP_SLOT))) + rela.AddUint64(ctxt.Arch, 0) + } else { + ctxt.Errorf(s, "addpltsym: unsupported binary format") + } +} + +// Generate the glink resolver stub if necessary and return the .glink section. +func ensureglinkresolver(ctxt *ld.Link, ldr *loader.Loader) *loader.SymbolBuilder { + glink := ldr.CreateSymForUpdate(".glink", 0) + if glink.Size() != 0 { + return glink + } + + // This is essentially the resolver from the ppc64 ELFv2 ABI. + // At entry, r12 holds the address of the symbol resolver stub + // for the target routine and the argument registers hold the + // arguments for the target routine. + // + // PC-rel offsets are computed once the final codesize of the + // resolver is known. + // + // This stub is PIC, so first get the PC of label 1 into r11. + glink.AddUint32(ctxt.Arch, 0x7c0802a6) // mflr r0 + glink.AddUint32(ctxt.Arch, 0x429f0005) // bcl 20,31,1f + glink.AddUint32(ctxt.Arch, 0x7d6802a6) // 1: mflr r11 + glink.AddUint32(ctxt.Arch, 0x7c0803a6) // mtlr r0 + + // Compute the .plt array index from the entry point address + // into r0. This is computed relative to label 1 above. + glink.AddUint32(ctxt.Arch, 0x38000000) // li r0,-(res_0-1b) + glink.AddUint32(ctxt.Arch, 0x7c006214) // add r0,r0,r12 + glink.AddUint32(ctxt.Arch, 0x7c0b0050) // sub r0,r0,r11 + glink.AddUint32(ctxt.Arch, 0x7800f082) // srdi r0,r0,2 + + // Load the PC-rel offset of ".plt - 1b", and add it to 1b. + // This is stored after this stub and before the resolvers. + glink.AddUint32(ctxt.Arch, 0xe98b0000) // ld r12,res_0-1b-8(r11) + glink.AddUint32(ctxt.Arch, 0x7d6b6214) // add r11,r11,r12 + + // Load r12 = dynamic resolver address and r11 = DSO + // identifier from the first two doublewords of the PLT. + glink.AddUint32(ctxt.Arch, 0xe98b0000) // ld r12,0(r11) + glink.AddUint32(ctxt.Arch, 0xe96b0008) // ld r11,8(r11) + + // Jump to the dynamic resolver + glink.AddUint32(ctxt.Arch, 0x7d8903a6) // mtctr r12 + glink.AddUint32(ctxt.Arch, 0x4e800420) // bctr + + // Store the PC-rel offset to the PLT + r, _ := glink.AddRel(objabi.R_PCREL) + r.SetSym(ctxt.PLT) + r.SetSiz(8) + r.SetOff(int32(glink.Size())) + r.SetAdd(glink.Size()) // Adjust the offset to be relative to label 1 above. + glink.AddUint64(ctxt.Arch, 0) // The offset to the PLT. + + // Resolve PC-rel offsets above now the final size of the stub is known. + res0m1b := glink.Size() - 8 // res_0 - 1b + glink.SetUint32(ctxt.Arch, 16, 0x38000000|uint32(uint16(-res0m1b))) + glink.SetUint32(ctxt.Arch, 32, 0xe98b0000|uint32(uint16(res0m1b-8))) + + // The symbol resolvers must immediately follow. + // res_0: + + // Add DT_PPC64_GLINK .dynamic entry, which points to 32 bytes + // before the first symbol resolver stub. + du := ldr.MakeSymbolUpdater(ctxt.Dynamic) + ld.Elfwritedynentsymplus(ctxt, du, elf.DT_PPC64_GLINK, glink.Sym(), glink.Size()-32) + + return glink +} |