| // Inferno utils/8l/asm.c |
| // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/8l/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 x86 |
| |
| import ( |
| "cmd/internal/objabi" |
| "cmd/internal/sys" |
| "cmd/link/internal/ld" |
| "cmd/link/internal/loader" |
| "cmd/link/internal/sym" |
| "debug/elf" |
| "log" |
| ) |
| |
| func gentext(ctxt *ld.Link, ldr *loader.Loader) { |
| if ctxt.DynlinkingGo() { |
| // We need get_pc_thunk. |
| } else { |
| switch ctxt.BuildMode { |
| case ld.BuildModeCArchive: |
| if !ctxt.IsELF { |
| return |
| } |
| case ld.BuildModePIE, ld.BuildModeCShared, ld.BuildModePlugin: |
| // We need get_pc_thunk. |
| default: |
| return |
| } |
| } |
| |
| // Generate little thunks that load the PC of the next instruction into a register. |
| thunks := make([]loader.Sym, 0, 7+len(ctxt.Textp)) |
| for _, r := range [...]struct { |
| name string |
| num uint8 |
| }{ |
| {"ax", 0}, |
| {"cx", 1}, |
| {"dx", 2}, |
| {"bx", 3}, |
| // sp |
| {"bp", 5}, |
| {"si", 6}, |
| {"di", 7}, |
| } { |
| thunkfunc := ldr.CreateSymForUpdate("__x86.get_pc_thunk."+r.name, 0) |
| thunkfunc.SetType(sym.STEXT) |
| ldr.SetAttrLocal(thunkfunc.Sym(), true) |
| o := func(op ...uint8) { |
| for _, op1 := range op { |
| thunkfunc.AddUint8(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) |
| |
| thunks = append(thunks, thunkfunc.Sym()) |
| } |
| ctxt.Textp = append(thunks, ctxt.Textp...) // keep Textp in dependency order |
| |
| initfunc, addmoduledata := ld.PrepareAddmoduledata(ctxt) |
| if initfunc == nil { |
| return |
| } |
| |
| o := func(op ...uint8) { |
| for _, op1 := range op { |
| initfunc.AddUint8(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) |
| initfunc.AddSymRef(ctxt.Arch, ldr.Lookup("__x86.get_pc_thunk.cx", 0), 0, objabi.R_CALL, 4) |
| |
| o(0x8d, 0x81) |
| initfunc.AddPCRelPlus(ctxt.Arch, ctxt.Moduledata, 6) |
| |
| o(0x8d, 0x99) |
| gotsym := ldr.LookupOrCreateSym("_GLOBAL_OFFSET_TABLE_", 0) |
| initfunc.AddSymRef(ctxt.Arch, gotsym, 12, objabi.R_PCREL, 4) |
| o(0xe8) |
| initfunc.AddSymRef(ctxt.Arch, addmoduledata, 0, objabi.R_CALL, 4) |
| |
| o(0x5b) |
| |
| o(0xc3) |
| } |
| |
| func adddynrel(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym, r loader.Reloc, rIdx int) bool { |
| targ := r.Sym() |
| var targType sym.SymKind |
| if targ != 0 { |
| targType = ldr.SymType(targ) |
| } |
| |
| 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_386_PC32): |
| if targType == sym.SDYNIMPORT { |
| ldr.Errorf(s, "unexpected R_386_PC32 relocation for dynamic symbol %s", ldr.SymName(targ)) |
| } |
| // TODO(mwhudson): the test of VisibilityHidden here probably doesn't make |
| // sense and should be removed when someone has thought about it properly. |
| if (targType == 0 || targType == sym.SXREF) && !ldr.AttrVisibilityHidden(targ) { |
| ldr.Errorf(s, "unknown symbol %s in pcrel", ldr.SymName(targ)) |
| } |
| su := ldr.MakeSymbolUpdater(s) |
| su.SetRelocType(rIdx, objabi.R_PCREL) |
| su.SetRelocAdd(rIdx, r.Add()+4) |
| return true |
| |
| case objabi.ElfRelocOffset + objabi.RelocType(elf.R_386_PLT32): |
| su := ldr.MakeSymbolUpdater(s) |
| su.SetRelocType(rIdx, objabi.R_PCREL) |
| su.SetRelocAdd(rIdx, r.Add()+4) |
| if targType == sym.SDYNIMPORT { |
| addpltsym(target, ldr, syms, targ) |
| su.SetRelocSym(rIdx, syms.PLT) |
| su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymPlt(targ))) |
| } |
| |
| return true |
| |
| case objabi.ElfRelocOffset + objabi.RelocType(elf.R_386_GOT32), |
| objabi.ElfRelocOffset + objabi.RelocType(elf.R_386_GOT32X): |
| su := ldr.MakeSymbolUpdater(s) |
| if targType != sym.SDYNIMPORT { |
| // have symbol |
| sData := ldr.Data(s) |
| |
| if r.Off() >= 2 && sData[r.Off()-2] == 0x8b { |
| su.MakeWritable() |
| |
| // turn MOVL of GOT entry into LEAL of symbol address, relative to GOT. |
| writeableData := su.Data() |
| writeableData[r.Off()-2] = 0x8d |
| su.SetRelocType(rIdx, objabi.R_GOTOFF) |
| return true |
| } |
| |
| if r.Off() >= 2 && sData[r.Off()-2] == 0xff && sData[r.Off()-1] == 0xb3 { |
| su.MakeWritable() |
| // turn PUSHL of GOT entry into PUSHL of symbol itself. |
| // use unnecessary SS prefix to keep instruction same length. |
| writeableData := su.Data() |
| writeableData[r.Off()-2] = 0x36 |
| writeableData[r.Off()-1] = 0x68 |
| su.SetRelocType(rIdx, objabi.R_ADDR) |
| return true |
| } |
| |
| ldr.Errorf(s, "unexpected GOT reloc for non-dynamic symbol %s", ldr.SymName(targ)) |
| return false |
| } |
| |
| ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_386_GLOB_DAT)) |
| su.SetRelocType(rIdx, objabi.R_CONST) // write r->add during relocsym |
| su.SetRelocSym(rIdx, 0) |
| su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ))) |
| return true |
| |
| case objabi.ElfRelocOffset + objabi.RelocType(elf.R_386_GOTOFF): |
| su := ldr.MakeSymbolUpdater(s) |
| su.SetRelocType(rIdx, objabi.R_GOTOFF) |
| return true |
| |
| case objabi.ElfRelocOffset + objabi.RelocType(elf.R_386_GOTPC): |
| su := ldr.MakeSymbolUpdater(s) |
| su.SetRelocType(rIdx, objabi.R_PCREL) |
| su.SetRelocSym(rIdx, syms.GOT) |
| su.SetRelocAdd(rIdx, r.Add()+4) |
| return true |
| |
| case objabi.ElfRelocOffset + objabi.RelocType(elf.R_386_32): |
| if targType == sym.SDYNIMPORT { |
| ldr.Errorf(s, "unexpected R_386_32 relocation for dynamic symbol %s", ldr.SymName(targ)) |
| } |
| su := ldr.MakeSymbolUpdater(s) |
| su.SetRelocType(rIdx, objabi.R_ADDR) |
| return true |
| |
| case objabi.MachoRelocOffset + ld.MACHO_GENERIC_RELOC_VANILLA*2 + 0: |
| su := ldr.MakeSymbolUpdater(s) |
| su.SetRelocType(rIdx, objabi.R_ADDR) |
| if targType == sym.SDYNIMPORT { |
| ldr.Errorf(s, "unexpected reloc for dynamic symbol %s", ldr.SymName(targ)) |
| } |
| return true |
| |
| case objabi.MachoRelocOffset + ld.MACHO_GENERIC_RELOC_VANILLA*2 + 1: |
| su := ldr.MakeSymbolUpdater(s) |
| if targType == sym.SDYNIMPORT { |
| addpltsym(target, ldr, syms, targ) |
| su.SetRelocSym(rIdx, syms.PLT) |
| su.SetRelocAdd(rIdx, int64(ldr.SymPlt(targ))) |
| su.SetRelocType(rIdx, objabi.R_PCREL) |
| return true |
| } |
| |
| su.SetRelocType(rIdx, objabi.R_PCREL) |
| return true |
| |
| case objabi.MachoRelocOffset + ld.MACHO_FAKE_GOTPCREL: |
| su := ldr.MakeSymbolUpdater(s) |
| if targType != sym.SDYNIMPORT { |
| // have symbol |
| // turn MOVL of GOT entry into LEAL of symbol itself |
| sData := ldr.Data(s) |
| if r.Off() < 2 || sData[r.Off()-2] != 0x8b { |
| ldr.Errorf(s, "unexpected GOT reloc for non-dynamic symbol %s", ldr.SymName(targ)) |
| return false |
| } |
| |
| su.MakeWritable() |
| writeableData := su.Data() |
| writeableData[r.Off()-2] = 0x8d |
| su.SetRelocType(rIdx, objabi.R_PCREL) |
| return true |
| } |
| |
| ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_386_GLOB_DAT)) |
| su.SetRelocSym(rIdx, syms.GOT) |
| su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ))) |
| su.SetRelocType(rIdx, objabi.R_PCREL) |
| return true |
| } |
| |
| // Handle references to ELF symbols from our own object files. |
| if targType != sym.SDYNIMPORT { |
| return true |
| } |
| |
| // Reread the reloc to incorporate any changes in type above. |
| relocs := ldr.Relocs(s) |
| r = relocs.At(rIdx) |
| |
| switch r.Type() { |
| case objabi.R_CALL, |
| objabi.R_PCREL: |
| if target.IsExternal() { |
| // External linker will do this relocation. |
| return true |
| } |
| addpltsym(target, ldr, syms, targ) |
| su := ldr.MakeSymbolUpdater(s) |
| su.SetRelocSym(rIdx, syms.PLT) |
| su.SetRelocAdd(rIdx, int64(ldr.SymPlt(targ))) |
| return true |
| |
| case objabi.R_ADDR: |
| if ldr.SymType(s) != sym.SDATA { |
| break |
| } |
| if target.IsElf() { |
| ld.Adddynsym(ldr, target, syms, targ) |
| rel := ldr.MakeSymbolUpdater(syms.Rel) |
| rel.AddAddrPlus(target.Arch, s, int64(r.Off())) |
| rel.AddUint32(target.Arch, elf.R_INFO32(uint32(ldr.SymDynid(targ)), uint32(elf.R_386_32))) |
| su := ldr.MakeSymbolUpdater(s) |
| su.SetRelocType(rIdx, objabi.R_CONST) // write r->add during relocsym |
| su.SetRelocSym(rIdx, 0) |
| return true |
| } |
| } |
| |
| return false |
| } |
| |
| func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, ri int, sectoff int64) bool { |
| out.Write32(uint32(sectoff)) |
| |
| elfsym := ld.ElfSymForReloc(ctxt, r.Xsym) |
| siz := r.Size |
| switch r.Type { |
| default: |
| return false |
| case objabi.R_ADDR, objabi.R_DWARFSECREF: |
| if siz == 4 { |
| out.Write32(uint32(elf.R_386_32) | uint32(elfsym)<<8) |
| } else { |
| return false |
| } |
| case objabi.R_GOTPCREL: |
| if siz == 4 { |
| out.Write32(uint32(elf.R_386_GOTPC)) |
| if ldr.SymName(r.Xsym) != "_GLOBAL_OFFSET_TABLE_" { |
| out.Write32(uint32(sectoff)) |
| out.Write32(uint32(elf.R_386_GOT32) | uint32(elfsym)<<8) |
| } |
| } else { |
| return false |
| } |
| case objabi.R_CALL: |
| if siz == 4 { |
| if ldr.SymType(r.Xsym) == sym.SDYNIMPORT { |
| out.Write32(uint32(elf.R_386_PLT32) | uint32(elfsym)<<8) |
| } else { |
| out.Write32(uint32(elf.R_386_PC32) | uint32(elfsym)<<8) |
| } |
| } else { |
| return false |
| } |
| case objabi.R_PCREL: |
| if siz == 4 { |
| out.Write32(uint32(elf.R_386_PC32) | uint32(elfsym)<<8) |
| } else { |
| return false |
| } |
| case objabi.R_TLS_LE: |
| if siz == 4 { |
| out.Write32(uint32(elf.R_386_TLS_LE) | uint32(elfsym)<<8) |
| } else { |
| return false |
| } |
| case objabi.R_TLS_IE: |
| if siz == 4 { |
| out.Write32(uint32(elf.R_386_GOTPC)) |
| out.Write32(uint32(sectoff)) |
| out.Write32(uint32(elf.R_386_TLS_GOTIE) | uint32(elfsym)<<8) |
| } else { |
| return false |
| } |
| } |
| |
| return true |
| } |
| |
| func machoreloc1(*sys.Arch, *ld.OutBuf, *loader.Loader, loader.Sym, loader.ExtReloc, int64) bool { |
| return false |
| } |
| |
| func pereloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool { |
| var v uint32 |
| |
| rs := r.Xsym |
| rt := r.Type |
| |
| if ldr.SymDynid(rs) < 0 { |
| ldr.Errorf(s, "reloc %d (%s) to non-coff symbol %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymType(rs), ldr.SymType(rs)) |
| return false |
| } |
| |
| out.Write32(uint32(sectoff)) |
| out.Write32(uint32(ldr.SymDynid(rs))) |
| |
| switch rt { |
| default: |
| return false |
| |
| case objabi.R_DWARFSECREF: |
| v = ld.IMAGE_REL_I386_SECREL |
| |
| case objabi.R_ADDR: |
| v = ld.IMAGE_REL_I386_DIR32 |
| |
| case objabi.R_CALL, |
| objabi.R_PCREL: |
| v = ld.IMAGE_REL_I386_REL32 |
| } |
| |
| out.Write16(uint16(v)) |
| |
| return true |
| } |
| |
| func archreloc(*ld.Target, *loader.Loader, *ld.ArchSyms, loader.Reloc, loader.Sym, int64) (int64, int, bool) { |
| return -1, 0, false |
| } |
| |
| func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 { |
| log.Fatalf("unexpected relocation variant") |
| return -1 |
| } |
| |
| func elfsetupplt(ctxt *ld.Link, plt, got *loader.SymbolBuilder, dynamic loader.Sym) { |
| if plt.Size() == 0 { |
| // pushl got+4 |
| plt.AddUint8(0xff) |
| |
| plt.AddUint8(0x35) |
| plt.AddAddrPlus(ctxt.Arch, got.Sym(), 4) |
| |
| // jmp *got+8 |
| plt.AddUint8(0xff) |
| |
| plt.AddUint8(0x25) |
| plt.AddAddrPlus(ctxt.Arch, got.Sym(), 8) |
| |
| // zero pad |
| plt.AddUint32(ctxt.Arch, 0) |
| |
| // assume got->size == 0 too |
| got.AddAddrPlus(ctxt.Arch, dynamic, 0) |
| |
| got.AddUint32(ctxt.Arch, 0) |
| got.AddUint32(ctxt.Arch, 0) |
| } |
| } |
| |
| func addpltsym(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym) { |
| if ldr.SymPlt(s) >= 0 { |
| return |
| } |
| |
| ld.Adddynsym(ldr, target, syms, s) |
| |
| if target.IsElf() { |
| plt := ldr.MakeSymbolUpdater(syms.PLT) |
| got := ldr.MakeSymbolUpdater(syms.GOTPLT) |
| rel := ldr.MakeSymbolUpdater(syms.RelPLT) |
| if plt.Size() == 0 { |
| panic("plt is not set up") |
| } |
| |
| // jmpq *got+size |
| plt.AddUint8(0xff) |
| |
| plt.AddUint8(0x25) |
| plt.AddAddrPlus(target.Arch, got.Sym(), got.Size()) |
| |
| // add to got: pointer to current pos in plt |
| got.AddAddrPlus(target.Arch, plt.Sym(), plt.Size()) |
| |
| // pushl $x |
| plt.AddUint8(0x68) |
| |
| plt.AddUint32(target.Arch, uint32(rel.Size())) |
| |
| // jmp .plt |
| plt.AddUint8(0xe9) |
| |
| plt.AddUint32(target.Arch, uint32(-(plt.Size() + 4))) |
| |
| // rel |
| rel.AddAddrPlus(target.Arch, got.Sym(), got.Size()-4) |
| |
| sDynid := ldr.SymDynid(s) |
| rel.AddUint32(target.Arch, elf.R_INFO32(uint32(sDynid), uint32(elf.R_386_JMP_SLOT))) |
| |
| ldr.SetPlt(s, int32(plt.Size()-16)) |
| } else { |
| ldr.Errorf(s, "addpltsym: unsupported binary format") |
| } |
| } |
