// 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" "strings" "sync" ) func genplt2(ctxt *ld.Link, ldr *loader.Loader) { // 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. var stubs []loader.Sym for _, s := range ctxt.Textp2 { relocs := ldr.Relocs(s) for i := 0; i < relocs.Count(); i++ { r := relocs.At2(i) if r.Type() != objabi.ElfRelocOffset+objabi.RelocType(elf.R_PPC64_REL24) || ldr.SymType(r.Sym()) != sym.SDYNIMPORT { continue } // Reserve PLT entry and generate symbol // resolver addpltsym2(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)) if stub.Size() == 0 { stubs = append(stubs, stub.Sym()) gencallstub2(ctxt, ldr, 1, stub, r.Sym()) } // Update the relocation to use the call stub r.SetSym(stub.Sym()) // make sure the data is writeable if ldr.AttrReadOnly(s) { panic("can't write to read-only sym data") } // Restore TOC after bl. The compiler put a // nop here for us to overwrite. sp := ldr.Data(s) const o1 = 0xe8410018 // ld r2,24(r1) ctxt.Arch.ByteOrder.PutUint32(sp[r.Off()+4:], o1) } } // Put call 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.Textp2 = append(stubs, ctxt.Textp2...) } func genaddmoduledata2(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.DotTOC2[0] rel1 := loader.Reloc{ Off: 0, Size: 8, Type: objabi.R_ADDRPOWER_PCREL, Sym: toc, } initfunc.AddReloc(rel1) 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 := loader.Reloc{ Off: int32(initfunc.Size()), Size: 8, Type: objabi.R_ADDRPOWER_GOT, Sym: tgt, } initfunc.AddReloc(rel2) o(0x3c620000) // ld r3, local.moduledata@got@l(r3) o(0xe8630000) // bl runtime.addmoduledata rel3 := loader.Reloc{ Off: int32(initfunc.Size()), Size: 4, Type: objabi.R_CALLPOWER, Sym: addmoduledata, } initfunc.AddReloc(rel3) o(0x48000001) // nop o(0x60000000) // ld r31, 0(r1) o(0xe8010000) // mtlr r31 o(0x7c0803a6) // addi r1,r1,32 o(0x38210020) // blr o(0x4e800020) } func gentext2(ctxt *ld.Link, ldr *loader.Loader) { if ctxt.DynlinkingGo() { genaddmoduledata2(ctxt, ldr) } if ctxt.LinkMode == ld.LinkInternal { genplt2(ctxt, ldr) } } // Construct a call stub in stub that calls symbol targ via its PLT // entry. func gencallstub2(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.PLT2 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 := loader.Reloc{ Off: int32(stub.Size()), Size: 2, Add: int64(ldr.SymPlt(targ)), Type: objabi.R_POWER_TOC, Sym: plt, } if ctxt.Arch.ByteOrder == binary.BigEndian { rel.Off += int32(rel.Size) } ri1 := stub.AddReloc(rel) ldr.SetRelocVariant(stub.Sym(), int(ri1), sym.RV_POWER_HA) stub.AddUint32(ctxt.Arch, 0x3d820000) // addis r12,r2,targ@plt@toc@ha rel2 := loader.Reloc{ Off: int32(stub.Size()), Size: 2, Add: int64(ldr.SymPlt(targ)), Type: objabi.R_POWER_TOC, Sym: plt, } if ctxt.Arch.ByteOrder == binary.BigEndian { rel2.Off += int32(rel.Size) } ri2 := stub.AddReloc(rel2) 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 } func adddynrel2(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym, r loader.Reloc2, rIdx int) bool { if target.IsElf() { return addelfdynrel2(target, ldr, syms, s, r, rIdx) } else if target.IsAIX() { return ld.Xcoffadddynrel2(target, ldr, syms, s, r, rIdx) } return false } func addelfdynrel2(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym, r loader.Reloc2, 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))*4) 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.Adddynsym2(ldr, target, syms, targ) rela := ldr.MakeSymbolUpdater(syms.Rela2) rela.AddAddrPlus(target.Arch, s, int64(r.Off())) rela.AddUint64(target.Arch, ld.ELF64_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 } 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 } // Handle references to ELF symbols from our own object files. if targType != sym.SDYNIMPORT { return true } // TODO(austin): Translate our relocations to ELF return false } func xcoffreloc1(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, sectoff int64) bool { rs := r.Xsym emitReloc := func(v uint16, off uint64) { out.Write64(uint64(sectoff) + off) out.Write32(uint32(rs.Dynid)) out.Write16(v) } var v uint16 switch r.Type { default: return false case objabi.R_ADDR: v = ld.XCOFF_R_POS if r.Siz == 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: emitReloc(ld.XCOFF_R_TLS_LE|0x0F<<8, 2) case objabi.R_CALLPOWER: if r.Siz != 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, r *sym.Reloc, sectoff int64) bool { // Beware that bit0~bit15 start from the third byte of a instruction in Big-Endian machines. if r.Type == objabi.R_ADDR || r.Type == objabi.R_POWER_TLS || r.Type == objabi.R_CALLPOWER { } else { if ctxt.Arch.ByteOrder == binary.BigEndian { sectoff += 2 } } ctxt.Out.Write64(uint64(sectoff)) elfsym := ld.ElfSymForReloc(ctxt, r.Xsym) switch r.Type { default: return false case objabi.R_ADDR, objabi.R_DWARFSECREF: switch r.Siz { case 4: ctxt.Out.Write64(uint64(elf.R_PPC64_ADDR32) | uint64(elfsym)<<32) case 8: ctxt.Out.Write64(uint64(elf.R_PPC64_ADDR64) | uint64(elfsym)<<32) default: return false } case objabi.R_POWER_TLS: ctxt.Out.Write64(uint64(elf.R_PPC64_TLS) | uint64(elfsym)<<32) case objabi.R_POWER_TLS_LE: ctxt.Out.Write64(uint64(elf.R_PPC64_TPREL16) | uint64(elfsym)<<32) case objabi.R_POWER_TLS_IE: ctxt.Out.Write64(uint64(elf.R_PPC64_GOT_TPREL16_HA) | uint64(elfsym)<<32) ctxt.Out.Write64(uint64(r.Xadd)) ctxt.Out.Write64(uint64(sectoff + 4)) ctxt.Out.Write64(uint64(elf.R_PPC64_GOT_TPREL16_LO_DS) | uint64(elfsym)<<32) case objabi.R_ADDRPOWER: ctxt.Out.Write64(uint64(elf.R_PPC64_ADDR16_HA) | uint64(elfsym)<<32) ctxt.Out.Write64(uint64(r.Xadd)) ctxt.Out.Write64(uint64(sectoff + 4)) ctxt.Out.Write64(uint64(elf.R_PPC64_ADDR16_LO) | uint64(elfsym)<<32) case objabi.R_ADDRPOWER_DS: ctxt.Out.Write64(uint64(elf.R_PPC64_ADDR16_HA) | uint64(elfsym)<<32) ctxt.Out.Write64(uint64(r.Xadd)) ctxt.Out.Write64(uint64(sectoff + 4)) ctxt.Out.Write64(uint64(elf.R_PPC64_ADDR16_LO_DS) | uint64(elfsym)<<32) case objabi.R_ADDRPOWER_GOT: ctxt.Out.Write64(uint64(elf.R_PPC64_GOT16_HA) | uint64(elfsym)<<32) ctxt.Out.Write64(uint64(r.Xadd)) ctxt.Out.Write64(uint64(sectoff + 4)) ctxt.Out.Write64(uint64(elf.R_PPC64_GOT16_LO_DS) | uint64(elfsym)<<32) case objabi.R_ADDRPOWER_PCREL: ctxt.Out.Write64(uint64(elf.R_PPC64_REL16_HA) | uint64(elfsym)<<32) ctxt.Out.Write64(uint64(r.Xadd)) ctxt.Out.Write64(uint64(sectoff + 4)) ctxt.Out.Write64(uint64(elf.R_PPC64_REL16_LO) | uint64(elfsym)<<32) r.Xadd += 4 case objabi.R_ADDRPOWER_TOCREL: ctxt.Out.Write64(uint64(elf.R_PPC64_TOC16_HA) | uint64(elfsym)<<32) ctxt.Out.Write64(uint64(r.Xadd)) ctxt.Out.Write64(uint64(sectoff + 4)) ctxt.Out.Write64(uint64(elf.R_PPC64_TOC16_LO) | uint64(elfsym)<<32) case objabi.R_ADDRPOWER_TOCREL_DS: ctxt.Out.Write64(uint64(elf.R_PPC64_TOC16_HA) | uint64(elfsym)<<32) ctxt.Out.Write64(uint64(r.Xadd)) ctxt.Out.Write64(uint64(sectoff + 4)) ctxt.Out.Write64(uint64(elf.R_PPC64_TOC16_LO_DS) | uint64(elfsym)<<32) case objabi.R_CALLPOWER: if r.Siz != 4 { return false } ctxt.Out.Write64(uint64(elf.R_PPC64_REL24) | uint64(elfsym)<<32) } ctxt.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(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, sectoff int64) bool { return false } // Return the value of .TOC. for symbol s func symtoc(syms *ld.ArchSyms, s *sym.Symbol) int64 { v := s.Version if s.Outer != nil { v = s.Outer.Version } toc := syms.DotTOC[v] if toc == nil { ld.Errorf(s, "TOC-relative relocation in object without .TOC.") return 0 } return toc.Value } // archreloctoc relocates a TOC relative symbol. // If the symbol pointed by this TOC relative symbol is in .data or .bss, the // default load instruction can be changed to an addi instruction and the // symbol address can be used directly. // This code is for AIX only. func archreloctoc(target *ld.Target, syms *ld.ArchSyms, r *sym.Reloc, s *sym.Symbol, val int64) int64 { if target.IsLinux() { ld.Errorf(s, "archrelocaddr called for %s relocation\n", r.Sym.Name) } var o1, o2 uint32 o1 = uint32(val >> 32) o2 = uint32(val) var t int64 useAddi := false const prefix = "TOC." var tarSym *sym.Symbol if strings.HasPrefix(r.Sym.Name, prefix) { tarSym = r.Sym.R[0].Sym } else { ld.Errorf(s, "archreloctoc called for a symbol without TOC anchor") } if target.IsInternal() && tarSym != nil && tarSym.Attr.Reachable() && (tarSym.Sect.Seg == &ld.Segdata) { t = ld.Symaddr(tarSym) + r.Add - syms.TOC.Value // change ld to addi in the second instruction o2 = (o2 & 0x03FF0000) | 0xE<<26 useAddi = true } else { t = ld.Symaddr(r.Sym) + r.Add - syms.TOC.Value } if t != int64(int32(t)) { ld.Errorf(s, "TOC relocation for %s is too big to relocate %s: 0x%x", s.Name, r.Sym, 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 { ld.Errorf(s, "bad DS reloc for %s: %d", s.Name, ld.Symaddr(r.Sym)) } o2 |= uint32(t) & 0xFFFC } default: return -1 } return int64(o1)<<32 | int64(o2) } // archrelocaddr relocates a symbol address. // This code is for AIX only. func archrelocaddr(target *ld.Target, syms *ld.ArchSyms, r *sym.Reloc, s *sym.Symbol, val int64) int64 { if target.IsAIX() { ld.Errorf(s, "archrelocaddr called for %s relocation\n", r.Sym.Name) } var o1, o2 uint32 if target.IsBigEndian() { o1 = uint32(val >> 32) o2 = uint32(val) } else { o1 = uint32(val) o2 = uint32(val >> 32) } // We are spreading a 31-bit address across two instructions, putting the // high (adjusted) part in the low 16 bits of the first instruction and the // low part in the low 16 bits of the second instruction, or, in the DS case, // bits 15-2 (inclusive) of the address into bits 15-2 of the second // instruction (it is an error in this case if the low 2 bits of the address // are non-zero). t := ld.Symaddr(r.Sym) + r.Add if t < 0 || t >= 1<<31 { ld.Errorf(s, "relocation for %s is too big (>=2G): 0x%x", s.Name, ld.Symaddr(r.Sym)) } if t&0x8000 != 0 { t += 0x10000 } switch r.Type { case objabi.R_ADDRPOWER: o1 |= (uint32(t) >> 16) & 0xffff o2 |= uint32(t) & 0xffff case objabi.R_ADDRPOWER_DS: o1 |= (uint32(t) >> 16) & 0xffff if t&3 != 0 { ld.Errorf(s, "bad DS reloc for %s: %d", s.Name, ld.Symaddr(r.Sym)) } o2 |= uint32(t) & 0xfffc default: return -1 } if target.IsBigEndian() { return int64(o1)<<32 | int64(o2) } return int64(o2)<<32 | int64(o1) } // 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) { // No trampolines needed since r2 contains the TOC return } relocs := ldr.Relocs(s) r := relocs.At2(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 } t = ldr.SymValue(tramp) + r.Add() - (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 { if r2Valid(ctxt) { // Should have returned for above cases ctxt.Errorf(s, "unexpected trampoline for shared or dynamic linking") } else { trampb := ldr.MakeSymbolUpdater(tramp) ctxt.AddTramp(trampb) gentramp(ctxt, ldr, trampb, rs, r.Add()) } } sb := ldr.MakeSymbolUpdater(s) relocs := sb.Relocs() r := relocs.At2(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()) t := ldr.SymValue(target) + offset 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(0x3fe20000) // lis r2, toctargetaddr hi o2 = uint32(0xebff0000) // ld r31, toctargetaddr lo toctramp := ldr.CreateSymForUpdate("TOC."+ldr.SymName(tramp.Sym()), 0) toctramp.SetType(sym.SXCOFFTOC) toctramp.SetReachable(true) toctramp.AddAddrPlus(ctxt.Arch, target, offset) r := loader.Reloc{ Off: 0, Type: objabi.R_ADDRPOWER_TOCREL_DS, Size: 8, // generates 2 relocations: HA + LO Sym: toctramp.Sym(), } tramp.AddReloc(r) } 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(0x3fe00000) // lis r31,targetaddr hi o2 = uint32(0x3bff0000) // addi r31,targetaddr lo // With external linking, the target address must be // relocated using LO and HA if ctxt.IsExternal() || ldr.SymValue(target) == 0 { r := loader.Reloc{ Off: 0, Type: objabi.R_ADDRPOWER, Size: 8, // generates 2 relocations: HA + LO Sym: target, Add: offset, } tramp.AddReloc(r) } else { // adjustment needed if lo has sign bit set // when using addi to compute address val := uint32((t & 0xffff0000) >> 16) if t&0x8000 != 0 { val += 1 } o1 |= val // hi part of addr o2 |= uint32(t & 0xffff) // lo part of addr } } o3 := uint32(0x7fe903a6) // mtctr r31 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) } func archreloc(target *ld.Target, syms *ld.ArchSyms, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) { if target.IsExternal() { // On AIX, relocations (except TLS ones) must be also done to the // value with the current addresses. switch r.Type { default: if target.IsAIX() { return val, false } case objabi.R_POWER_TLS, objabi.R_POWER_TLS_LE, objabi.R_POWER_TLS_IE: r.Done = false // check Outer is nil, Type is TLSBSS? r.Xadd = r.Add r.Xsym = r.Sym return val, 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: r.Done = false // set up addend for eventual relocation via outer symbol. rs := r.Sym r.Xadd = r.Add for rs.Outer != nil { r.Xadd += ld.Symaddr(rs) - ld.Symaddr(rs.Outer) rs = rs.Outer } if rs.Type != sym.SHOSTOBJ && rs.Type != sym.SDYNIMPORT && rs.Type != sym.SUNDEFEXT && rs.Sect == nil { ld.Errorf(s, "missing section for %s", rs.Name) } r.Xsym = rs if !target.IsAIX() { return val, true } case objabi.R_CALLPOWER: r.Done = false r.Xsym = r.Sym r.Xadd = r.Add if !target.IsAIX() { return val, true } } } switch r.Type { case objabi.R_CONST: return r.Add, true case objabi.R_GOTOFF: return ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(syms.GOT), true case objabi.R_ADDRPOWER_TOCREL, objabi.R_ADDRPOWER_TOCREL_DS: return archreloctoc(target, syms, r, s, val), true case objabi.R_ADDRPOWER, objabi.R_ADDRPOWER_DS: return archrelocaddr(target, syms, r, s, val), true case objabi.R_CALLPOWER: // Bits 6 through 29 = (S + A - P) >> 2 t := ld.Symaddr(r.Sym) + r.Add - (s.Value + int64(r.Off)) if t&3 != 0 { ld.Errorf(s, "relocation for %s+%d is not aligned: %d", r.Sym.Name, r.Off, t) } // If branch offset is too far then create a trampoline. if int64(int32(t<<6)>>6) != t { ld.Errorf(s, "direct call too far: %s %x", r.Sym.Name, t) } return val | int64(uint32(t)&^0xfc000003), true case objabi.R_POWER_TOC: // S + A - .TOC. return ld.Symaddr(r.Sym) + r.Add - symtoc(syms, s), true case objabi.R_POWER_TLS_LE: // 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 := r.Sym.Value - 0x7000 if target.IsAIX() { // On AIX, the thread pointer points 0x7800 bytes after // the TLS. v -= 0x800 } if int64(int16(v)) != v { ld.Errorf(s, "TLS offset out of range %d", v) } return (val &^ 0xffff) | (v & 0xffff), true } return val, false } func archrelocvariant(target *ld.Target, syms *ld.ArchSyms, r *sym.Reloc, s *sym.Symbol, t int64) int64 { switch r.Variant & sym.RV_TYPE_MASK { default: ld.Errorf(s, "unexpected relocation variant %d", r.Variant) fallthrough case sym.RV_NONE: return t case sym.RV_POWER_LO: if r.Variant&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(s.P[r.Off-2:]) } else { o1 = binary.LittleEndian.Uint32(s.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 r.Variant&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(s.P[r.Off-2:]) } else { o1 = binary.LittleEndian.Uint32(s.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(s.P[r.Off:])) } else { o1 = uint32(binary.LittleEndian.Uint16(s.P[r.Off:])) } if t&3 != 0 { ld.Errorf(s, "relocation for %s+%d is not aligned: %d", r.Sym.Name, r.Off, t) } if (r.Variant&sym.RV_CHECK_OVERFLOW != 0) && int64(int16(t)) != t { goto overflow } return int64(o1)&0x3 | int64(int16(t)) } overflow: ld.Errorf(s, "relocation for %s+%d is too big: %d", r.Sym.Name, r.Off, t) return t } func addpltsym2(ctxt *ld.Link, ldr *loader.Loader, s loader.Sym) { if ldr.SymPlt(s) >= 0 { return } ld.Adddynsym2(ldr, &ctxt.Target, &ctxt.ArchSyms, s) if ctxt.IsELF { plt := ldr.MakeSymbolUpdater(ctxt.PLT2) rela := ldr.MakeSymbolUpdater(ctxt.RelaPLT2) if plt.Size() == 0 { panic("plt is not set up") } // Create the glink resolver if necessary glink := ensureglinkresolver2(ctxt, ldr) // Write symbol resolver stub (just a branch to the // glink resolver stub) rel := loader.Reloc{ Off: int32(glink.Size()), Size: 4, Type: objabi.R_CALLPOWER, Sym: glink.Sym(), } glink.AddReloc(rel) 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) rela.AddAddrPlus(ctxt.Arch, plt.Sym(), int64(ldr.SymPlt(s))) rela.AddUint64(ctxt.Arch, ld.ELF64_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 ensureglinkresolver2(ctxt *ld.Link, ldr *loader.Loader) *loader.SymbolBuilder { gs := ldr.LookupOrCreateSym(".glink", 0) glink := ldr.MakeSymbolUpdater(gs) if glink.Size() != 0 { return glink } // This is essentially the resolver from the ppc64 ELF 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. // // This stub is PIC, so first get the PC of label 1 into r11. // Other things will be relative to this. 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) // mtlf r0 // Compute the .plt array index from the entry point address. // Because this is PIC, everything is relative to label 1b (in // r11): // r0 = ((r12 - r11) - (res_0 - r11)) / 4 = (r12 - res_0) / 4 glink.AddUint32(ctxt.Arch, 0x3800ffd0) // li r0,-(res_0-1b)=-48 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 // r11 = address of the first byte of the PLT glink.AddSymRef(ctxt.Arch, ctxt.PLT2, 0, objabi.R_ADDRPOWER, 8) glink.AddUint32(ctxt.Arch, 0x3d600000) // addis r11,0,.plt@ha glink.AddUint32(ctxt.Arch, 0x396b0000) // addi r11,r11,.plt@l // 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 // 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.Dynamic2) ld.Elfwritedynentsymplus2(ctxt, du, ld.DT_PPC64_GLINK, glink.Sym(), glink.Size()-32) return glink } func asmb(ctxt *ld.Link, _ *loader.Loader) { if ctxt.IsELF { ld.Asmbelfsetup() } var wg sync.WaitGroup for _, sect := range ld.Segtext.Sections { offset := sect.Vaddr - ld.Segtext.Vaddr + ld.Segtext.Fileoff // Handle additional text sections with Codeblk if sect.Name == ".text" { ld.WriteParallel(&wg, ld.Codeblk, ctxt, offset, sect.Vaddr, sect.Length) } else { ld.WriteParallel(&wg, ld.Datblk, ctxt, offset, sect.Vaddr, sect.Length) } } if ld.Segrodata.Filelen > 0 { ld.WriteParallel(&wg, ld.Datblk, ctxt, ld.Segrodata.Fileoff, ld.Segrodata.Vaddr, ld.Segrodata.Filelen) } if ld.Segrelrodata.Filelen > 0 { ld.WriteParallel(&wg, ld.Datblk, ctxt, ld.Segrelrodata.Fileoff, ld.Segrelrodata.Vaddr, ld.Segrelrodata.Filelen) } ld.WriteParallel(&wg, ld.Datblk, ctxt, ld.Segdata.Fileoff, ld.Segdata.Vaddr, ld.Segdata.Filelen) ld.WriteParallel(&wg, ld.Dwarfblk, ctxt, ld.Segdwarf.Fileoff, ld.Segdwarf.Vaddr, ld.Segdwarf.Filelen) wg.Wait() } func asmb2(ctxt *ld.Link) { /* output symbol table */ ld.Symsize = 0 ld.Lcsize = 0 symo := uint32(0) if !*ld.FlagS { // TODO: rationalize switch ctxt.HeadType { default: if ctxt.IsELF { symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen) symo = uint32(ld.Rnd(int64(symo), int64(*ld.FlagRound))) } case objabi.Hplan9: symo = uint32(ld.Segdata.Fileoff + ld.Segdata.Filelen) case objabi.Haix: // Nothing to do } ctxt.Out.SeekSet(int64(symo)) switch ctxt.HeadType { default: if ctxt.IsELF { ld.Asmelfsym(ctxt) ctxt.Out.Write(ld.Elfstrdat) if ctxt.LinkMode == ld.LinkExternal { ld.Elfemitreloc(ctxt) } } case objabi.Hplan9: ld.Asmplan9sym(ctxt) sym := ctxt.Syms.Lookup("pclntab", 0) if sym != nil { ld.Lcsize = int32(len(sym.P)) ctxt.Out.Write(sym.P) } case objabi.Haix: // symtab must be added once sections have been created in ld.Asmbxcoff } } ctxt.Out.SeekSet(0) switch ctxt.HeadType { default: case objabi.Hplan9: /* plan 9 */ ctxt.Out.Write32(0x647) /* magic */ ctxt.Out.Write32(uint32(ld.Segtext.Filelen)) /* sizes */ ctxt.Out.Write32(uint32(ld.Segdata.Filelen)) ctxt.Out.Write32(uint32(ld.Segdata.Length - ld.Segdata.Filelen)) ctxt.Out.Write32(uint32(ld.Symsize)) /* nsyms */ ctxt.Out.Write32(uint32(ld.Entryvalue(ctxt))) /* va of entry */ ctxt.Out.Write32(0) ctxt.Out.Write32(uint32(ld.Lcsize)) case objabi.Hlinux, objabi.Hfreebsd, objabi.Hnetbsd, objabi.Hopenbsd: ld.Asmbelf(ctxt, int64(symo)) case objabi.Haix: fileoff := uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen) fileoff = uint32(ld.Rnd(int64(fileoff), int64(*ld.FlagRound))) ld.Asmbxcoff(ctxt, int64(fileoff)) } if *ld.FlagC { fmt.Printf("textsize=%d\n", ld.Segtext.Filelen) fmt.Printf("datsize=%d\n", ld.Segdata.Filelen) fmt.Printf("bsssize=%d\n", ld.Segdata.Length-ld.Segdata.Filelen) fmt.Printf("symsize=%d\n", ld.Symsize) fmt.Printf("lcsize=%d\n", ld.Lcsize) fmt.Printf("total=%d\n", ld.Segtext.Filelen+ld.Segdata.Length+uint64(ld.Symsize)+uint64(ld.Lcsize)) } }