// 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 arm import ( "cmd/internal/objabi" "cmd/internal/sys" "cmd/link/internal/ld" "cmd/link/internal/loader" "cmd/link/internal/sym" "debug/elf" "fmt" "log" ) // This assembler: // // .align 2 // local.dso_init: // ldr r0, .Lmoduledata // .Lloadfrom: // ldr r0, [r0] // b runtime.addmoduledata@plt // .align 2 // .Lmoduledata: // .word local.moduledata(GOT_PREL) + (. - (.Lloadfrom + 4)) // assembles to: // // 00000000 : // 0: e59f0004 ldr r0, [pc, #4] ; c // 4: e5900000 ldr r0, [r0] // 8: eafffffe b 0 // 8: R_ARM_JUMP24 runtime.addmoduledata // c: 00000004 .word 0x00000004 // c: R_ARM_GOT_PREL local.moduledata func gentext(ctxt *ld.Link, ldr *loader.Loader) { initfunc, addmoduledata := ld.PrepareAddmoduledata(ctxt) if initfunc == nil { return } o := func(op uint32) { initfunc.AddUint32(ctxt.Arch, op) } o(0xe59f0004) o(0xe08f0000) o(0xeafffffe) rel, _ := initfunc.AddRel(objabi.R_CALLARM) rel.SetOff(8) rel.SetSiz(4) rel.SetSym(addmoduledata) rel.SetAdd(0xeafffffe) // vomit o(0x00000000) rel2, _ := initfunc.AddRel(objabi.R_PCREL) rel2.SetOff(12) rel2.SetSiz(4) rel2.SetSym(ctxt.Moduledata) rel2.SetAdd(4) } // Preserve highest 8 bits of a, and do addition to lower 24-bit // of a and b; used to adjust ARM branch instruction's target. func braddoff(a int32, b int32) int32 { return int32((uint32(a))&0xff000000 | 0x00ffffff&uint32(a+b)) } 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_ARM_PLT32): su := ldr.MakeSymbolUpdater(s) su.SetRelocType(rIdx, objabi.R_CALLARM) if targType == sym.SDYNIMPORT { addpltsym(target, ldr, syms, targ) su.SetRelocSym(rIdx, syms.PLT) su.SetRelocAdd(rIdx, int64(braddoff(int32(r.Add()), ldr.SymPlt(targ)/4))) } return true case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_THM_PC22): // R_ARM_THM_CALL ld.Exitf("R_ARM_THM_CALL, are you using -marm?") return false case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_GOT32): // R_ARM_GOT_BREL if targType != sym.SDYNIMPORT { addgotsyminternal(target, ldr, syms, targ) } else { ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_ARM_GLOB_DAT)) } su := ldr.MakeSymbolUpdater(s) 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_ARM_GOT_PREL): // GOT(nil) + A - nil if targType != sym.SDYNIMPORT { addgotsyminternal(target, ldr, syms, targ) } else { ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_ARM_GLOB_DAT)) } su := ldr.MakeSymbolUpdater(s) su.SetRelocType(rIdx, objabi.R_PCREL) su.SetRelocSym(rIdx, syms.GOT) su.SetRelocAdd(rIdx, r.Add()+4+int64(ldr.SymGot(targ))) return true case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_GOTOFF): // R_ARM_GOTOFF32 su := ldr.MakeSymbolUpdater(s) su.SetRelocType(rIdx, objabi.R_GOTOFF) return true case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_GOTPC): // R_ARM_BASE_PREL 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_ARM_CALL): su := ldr.MakeSymbolUpdater(s) su.SetRelocType(rIdx, objabi.R_CALLARM) if targType == sym.SDYNIMPORT { addpltsym(target, ldr, syms, targ) su.SetRelocSym(rIdx, syms.PLT) su.SetRelocAdd(rIdx, int64(braddoff(int32(r.Add()), ldr.SymPlt(targ)/4))) } return true case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_REL32): // R_ARM_REL32 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_ARM_ABS32): if targType == sym.SDYNIMPORT { ldr.Errorf(s, "unexpected R_ARM_ABS32 relocation for dynamic symbol %s", ldr.SymName(targ)) } su := ldr.MakeSymbolUpdater(s) su.SetRelocType(rIdx, objabi.R_ADDR) return true case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_PC24), objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_JUMP24): su := ldr.MakeSymbolUpdater(s) su.SetRelocType(rIdx, objabi.R_CALLARM) if targType == sym.SDYNIMPORT { addpltsym(target, ldr, syms, targ) su.SetRelocSym(rIdx, syms.PLT) su.SetRelocAdd(rIdx, int64(braddoff(int32(r.Add()), ldr.SymPlt(targ)/4))) } 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_CALLARM: 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(braddoff(int32(r.Add()), ldr.SymPlt(targ)/4))) // TODO: don't use r.Add for instruction bytes (issue 19811) 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_ARM_GLOB_DAT))) // we need a nil + A dynamic reloc su := ldr.MakeSymbolUpdater(s) su.SetRelocType(rIdx, objabi.R_CONST) // write r->add during relocsym su.SetRelocSym(rIdx, 0) return true } case objabi.R_GOTPCREL: if target.IsExternal() { // External linker will do this relocation. return true } if targType != sym.SDYNIMPORT { ldr.Errorf(s, "R_GOTPCREL target is not SDYNIMPORT symbol: %v", ldr.SymName(targ)) } ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_ARM_GLOB_DAT)) su := ldr.MakeSymbolUpdater(s) su.SetRelocType(rIdx, objabi.R_PCREL) su.SetRelocSym(rIdx, syms.GOT) su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ))) return true } return false } func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, ri int, sectoff int64) bool { out.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_ARM_ABS32) | uint32(elfsym)<<8) } else { return false } case objabi.R_PCREL: if siz == 4 { out.Write32(uint32(elf.R_ARM_REL32) | uint32(elfsym)<<8) } else { return false } case objabi.R_CALLARM: if siz == 4 { relocs := ldr.Relocs(s) r := relocs.At(ri) if r.Add()&0xff000000 == 0xeb000000 { // BL // TODO: using r.Add here is bad (issue 19811) out.Write32(uint32(elf.R_ARM_CALL) | uint32(elfsym)<<8) } else { out.Write32(uint32(elf.R_ARM_JUMP24) | uint32(elfsym)<<8) } } else { return false } case objabi.R_TLS_LE: out.Write32(uint32(elf.R_ARM_TLS_LE32) | uint32(elfsym)<<8) case objabi.R_TLS_IE: out.Write32(uint32(elf.R_ARM_TLS_IE32) | uint32(elfsym)<<8) case objabi.R_GOTPCREL: if siz == 4 { out.Write32(uint32(elf.R_ARM_GOT_PREL) | uint32(elfsym)<<8) } else { return false } } return true } func elfsetupplt(ctxt *ld.Link, ldr *loader.Loader, plt, got *loader.SymbolBuilder, dynamic loader.Sym) { if plt.Size() == 0 { // str lr, [sp, #-4]! plt.AddUint32(ctxt.Arch, 0xe52de004) // ldr lr, [pc, #4] plt.AddUint32(ctxt.Arch, 0xe59fe004) // add lr, pc, lr plt.AddUint32(ctxt.Arch, 0xe08fe00e) // ldr pc, [lr, #8]! plt.AddUint32(ctxt.Arch, 0xe5bef008) // .word &GLOBAL_OFFSET_TABLE[0] - . plt.AddPCRelPlus(ctxt.Arch, got.Sym(), 4) // the first .plt entry requires 3 .plt.got entries got.AddUint32(ctxt.Arch, 0) got.AddUint32(ctxt.Arch, 0) got.AddUint32(ctxt.Arch, 0) } } 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 { 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))) var v uint32 switch rt { default: // unsupported relocation type return false case objabi.R_DWARFSECREF: v = ld.IMAGE_REL_ARM_SECREL case objabi.R_ADDR: v = ld.IMAGE_REL_ARM_ADDR32 case objabi.R_PEIMAGEOFF: v = ld.IMAGE_REL_ARM_ADDR32NB } out.Write16(uint16(v)) return true } // sign extend a 24-bit integer. func signext24(x int64) int32 { return (int32(x) << 8) >> 8 } // encode an immediate in ARM's imm12 format. copied from ../../../internal/obj/arm/asm5.go func immrot(v uint32) uint32 { for i := 0; i < 16; i++ { if v&^0xff == 0 { return uint32(i<<8) | v | 1<<25 } v = v<<2 | v>>30 } return 0 } // Convert the direct jump relocation r to refer to a trampoline if the target is too far. func trampoline(ctxt *ld.Link, ldr *loader.Loader, ri int, rs, s loader.Sym) { relocs := ldr.Relocs(s) r := relocs.At(ri) switch r.Type() { case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_CALL), objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_PC24), objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_JUMP24): // Host object relocations that will be turned into a PLT call. // The PLT may be too far. Insert a trampoline for them. fallthrough case objabi.R_CALLARM: 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 { // Workaround for issue #58425: it appears that the // external linker doesn't always take into account the // relocation addend when doing reachability checks. This // means that if you have a call from function XYZ at // offset 8 to runtime.duffzero with addend 800 (for // example), where the distance between the start of XYZ // and the start of runtime.duffzero is just over the // limit (by 100 bytes, say), you can get "relocation // doesn't fit" errors from the external linker. To deal // with this, ignore the addend when performing the // distance calculation (this assumes that we're only // handling backward jumps; ideally we might want to check // both with and without the addend). if ctxt.IsExternal() { t = (ldr.SymValue(rs) - (ldr.SymValue(s) + int64(r.Off()))) / 4 } else { // r.Add is the instruction // low 24-bit encodes the target address t = (ldr.SymValue(rs) + int64(signext24(r.Add()&0xffffff)*4) - (ldr.SymValue(s) + int64(r.Off()))) / 4 } } if t > 0x7fffff || t <= -0x800000 || ldr.SymValue(rs) == 0 || (*ld.FlagDebugTramp > 1 && ldr.SymPkg(s) != ldr.SymPkg(rs)) { // direct call too far, need to insert trampoline. // look up existing trampolines first. if we found one within the range // of direct call, we can reuse it. otherwise create a new one. offset := (signext24(r.Add()&0xffffff) + 2) * 4 var tramp loader.Sym for i := 0; ; i++ { oName := ldr.SymName(rs) name := oName + fmt.Sprintf("%+d-tramp%d", offset, i) tramp = ldr.LookupOrCreateSym(name, int(ldr.SymVersion(rs))) ldr.SetAttrReachable(tramp, true) if ldr.SymType(tramp) == sym.SDYNIMPORT { // don't reuse trampoline defined in other module continue } if oName == "runtime.deferreturn" { ldr.SetIsDeferReturnTramp(tramp, true) } if ldr.SymValue(tramp) == 0 { // either the trampoline does not exist -- we need to create one, // or found one the address which is not assigned -- this will be // laid down immediately after the current function. use this one. break } t = (ldr.SymValue(tramp) - 8 - (ldr.SymValue(s) + int64(r.Off()))) / 4 if t >= -0x800000 && t < 0x7fffff { // found an existing trampoline that is not too far // we can just use it break } } if ldr.SymType(tramp) == 0 { // trampoline does not exist, create one trampb := ldr.MakeSymbolUpdater(tramp) ctxt.AddTramp(trampb) if ctxt.DynlinkingGo() || ldr.SymType(rs) == sym.SDYNIMPORT { if immrot(uint32(offset)) == 0 { ctxt.Errorf(s, "odd offset in dynlink direct call: %v+%d", ldr.SymName(rs), offset) } gentrampdyn(ctxt.Arch, trampb, rs, int64(offset)) } else if ctxt.BuildMode == ld.BuildModeCArchive || ctxt.BuildMode == ld.BuildModeCShared || ctxt.BuildMode == ld.BuildModePIE { gentramppic(ctxt.Arch, trampb, rs, int64(offset)) } else { gentramp(ctxt.Arch, ctxt.LinkMode, ldr, trampb, rs, int64(offset)) } } // modify reloc to point to tramp, which will be resolved later sb := ldr.MakeSymbolUpdater(s) relocs := sb.Relocs() r := relocs.At(ri) r.SetSym(tramp) r.SetAdd(r.Add()&0xff000000 | 0xfffffe) // clear the offset embedded in the instruction } default: ctxt.Errorf(s, "trampoline called with non-jump reloc: %d (%s)", r.Type(), sym.RelocName(ctxt.Arch, r.Type())) } } // generate a trampoline to target+offset. func gentramp(arch *sys.Arch, linkmode ld.LinkMode, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) { tramp.SetSize(12) // 3 instructions P := make([]byte, tramp.Size()) t := ldr.SymValue(target) + offset o1 := uint32(0xe5900000 | 12<<12 | 15<<16) // MOVW (R15), R12 // R15 is actual pc + 8 o2 := uint32(0xe12fff10 | 12) // JMP (R12) o3 := uint32(t) // WORD $target arch.ByteOrder.PutUint32(P, o1) arch.ByteOrder.PutUint32(P[4:], o2) arch.ByteOrder.PutUint32(P[8:], o3) tramp.SetData(P) if linkmode == ld.LinkExternal || ldr.SymValue(target) == 0 { r, _ := tramp.AddRel(objabi.R_ADDR) r.SetOff(8) r.SetSiz(4) r.SetSym(target) r.SetAdd(offset) } } // generate a trampoline to target+offset in position independent code. func gentramppic(arch *sys.Arch, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) { tramp.SetSize(16) // 4 instructions P := make([]byte, tramp.Size()) o1 := uint32(0xe5900000 | 12<<12 | 15<<16 | 4) // MOVW 4(R15), R12 // R15 is actual pc + 8 o2 := uint32(0xe0800000 | 12<<12 | 15<<16 | 12) // ADD R15, R12, R12 o3 := uint32(0xe12fff10 | 12) // JMP (R12) o4 := uint32(0) // WORD $(target-pc) // filled in with relocation arch.ByteOrder.PutUint32(P, o1) arch.ByteOrder.PutUint32(P[4:], o2) arch.ByteOrder.PutUint32(P[8:], o3) arch.ByteOrder.PutUint32(P[12:], o4) tramp.SetData(P) r, _ := tramp.AddRel(objabi.R_PCREL) r.SetOff(12) r.SetSiz(4) r.SetSym(target) r.SetAdd(offset + 4) } // generate a trampoline to target+offset in dynlink mode (using GOT). func gentrampdyn(arch *sys.Arch, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) { tramp.SetSize(20) // 5 instructions o1 := uint32(0xe5900000 | 12<<12 | 15<<16 | 8) // MOVW 8(R15), R12 // R15 is actual pc + 8 o2 := uint32(0xe0800000 | 12<<12 | 15<<16 | 12) // ADD R15, R12, R12 o3 := uint32(0xe5900000 | 12<<12 | 12<<16) // MOVW (R12), R12 o4 := uint32(0xe12fff10 | 12) // JMP (R12) o5 := uint32(0) // WORD $target@GOT // filled in with relocation o6 := uint32(0) if offset != 0 { // insert an instruction to add offset tramp.SetSize(24) // 6 instructions o6 = o5 o5 = o4 o4 = 0xe2800000 | 12<<12 | 12<<16 | immrot(uint32(offset)) // ADD $offset, R12, R12 o1 = uint32(0xe5900000 | 12<<12 | 15<<16 | 12) // MOVW 12(R15), R12 } P := make([]byte, tramp.Size()) arch.ByteOrder.PutUint32(P, o1) arch.ByteOrder.PutUint32(P[4:], o2) arch.ByteOrder.PutUint32(P[8:], o3) arch.ByteOrder.PutUint32(P[12:], o4) arch.ByteOrder.PutUint32(P[16:], o5) if offset != 0 { arch.ByteOrder.PutUint32(P[20:], o6) } tramp.SetData(P) r, _ := tramp.AddRel(objabi.R_GOTPCREL) r.SetOff(16) r.SetSiz(4) r.SetSym(target) r.SetAdd(8) if offset != 0 { // increase reloc offset by 4 as we inserted an ADD instruction r.SetOff(20) r.SetAdd(12) } } func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loader.Reloc, s loader.Sym, val int64) (o int64, nExtReloc int, ok bool) { rs := r.Sym() if target.IsExternal() { switch r.Type() { case objabi.R_CALLARM: // set up addend for eventual relocation via outer symbol. _, off := ld.FoldSubSymbolOffset(ldr, rs) xadd := int64(signext24(r.Add()&0xffffff))*4 + off if xadd/4 > 0x7fffff || xadd/4 < -0x800000 { ldr.Errorf(s, "direct call too far %d", xadd/4) } return int64(braddoff(int32(0xff000000&uint32(r.Add())), int32(0xffffff&uint32(xadd/4)))), 1, true } return -1, 0, false } const isOk = true const noExtReloc = 0 switch r.Type() { // The following three arch specific relocations are only for generation of // Linux/ARM ELF's PLT entry (3 assembler instruction) case objabi.R_PLT0: // add ip, pc, #0xXX00000 if ldr.SymValue(syms.GOTPLT) < ldr.SymValue(syms.PLT) { ldr.Errorf(s, ".got.plt should be placed after .plt section.") } return 0xe28fc600 + (0xff & (int64(uint32(ldr.SymValue(rs)-(ldr.SymValue(syms.PLT)+int64(r.Off()))+r.Add())) >> 20)), noExtReloc, isOk case objabi.R_PLT1: // add ip, ip, #0xYY000 return 0xe28cca00 + (0xff & (int64(uint32(ldr.SymValue(rs)-(ldr.SymValue(syms.PLT)+int64(r.Off()))+r.Add()+4)) >> 12)), noExtReloc, isOk case objabi.R_PLT2: // ldr pc, [ip, #0xZZZ]! return 0xe5bcf000 + (0xfff & int64(uint32(ldr.SymValue(rs)-(ldr.SymValue(syms.PLT)+int64(r.Off()))+r.Add()+8))), noExtReloc, isOk case objabi.R_CALLARM: // bl XXXXXX or b YYYYYY // r.Add is the instruction // low 24-bit encodes the target address t := (ldr.SymValue(rs) + int64(signext24(r.Add()&0xffffff)*4) - (ldr.SymValue(s) + int64(r.Off()))) / 4 if t > 0x7fffff || t < -0x800000 { ldr.Errorf(s, "direct call too far: %s %x", ldr.SymName(rs), t) } return int64(braddoff(int32(0xff000000&uint32(r.Add())), int32(0xffffff&t))), noExtReloc, isOk } return val, 0, false } func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 { log.Fatalf("unexpected relocation variant") return -1 } func extreloc(target *ld.Target, ldr *loader.Loader, r loader.Reloc, s loader.Sym) (loader.ExtReloc, bool) { rs := r.Sym() var rr loader.ExtReloc switch r.Type() { case objabi.R_CALLARM: // set up addend for eventual relocation via outer symbol. rs, off := ld.FoldSubSymbolOffset(ldr, rs) rr.Xadd = int64(signext24(r.Add()&0xffffff))*4 + off rst := ldr.SymType(rs) if rst != sym.SHOSTOBJ && rst != sym.SDYNIMPORT && rst != sym.SUNDEFEXT && ldr.SymSect(rs) == nil { ldr.Errorf(s, "missing section for %s", ldr.SymName(rs)) } rr.Xsym = rs rr.Type = r.Type() rr.Size = r.Siz() return rr, true } return rr, false } func addpltreloc(ldr *loader.Loader, plt *loader.SymbolBuilder, got *loader.SymbolBuilder, s loader.Sym, typ objabi.RelocType) { r, _ := plt.AddRel(typ) r.SetSym(got.Sym()) r.SetOff(int32(plt.Size())) r.SetSiz(4) r.SetAdd(int64(ldr.SymGot(s)) - 8) plt.SetReachable(true) plt.SetSize(plt.Size() + 4) plt.Grow(plt.Size()) } 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") } // .got entry ldr.SetGot(s, int32(got.Size())) // In theory, all GOT should point to the first PLT entry, // Linux/ARM's dynamic linker will do that for us, but FreeBSD/ARM's // dynamic linker won't, so we'd better do it ourselves. got.AddAddrPlus(target.Arch, plt.Sym(), 0) // .plt entry, this depends on the .got entry ldr.SetPlt(s, int32(plt.Size())) addpltreloc(ldr, plt, got, s, objabi.R_PLT0) // add lr, pc, #0xXX00000 addpltreloc(ldr, plt, got, s, objabi.R_PLT1) // add lr, lr, #0xYY000 addpltreloc(ldr, plt, got, s, objabi.R_PLT2) // ldr pc, [lr, #0xZZZ]! // rel rel.AddAddrPlus(target.Arch, got.Sym(), int64(ldr.SymGot(s))) rel.AddUint32(target.Arch, elf.R_INFO32(uint32(ldr.SymDynid(s)), uint32(elf.R_ARM_JUMP_SLOT))) } else { ldr.Errorf(s, "addpltsym: unsupported binary format") } } func addgotsyminternal(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym) { if ldr.SymGot(s) >= 0 { return } got := ldr.MakeSymbolUpdater(syms.GOT) ldr.SetGot(s, int32(got.Size())) got.AddAddrPlus(target.Arch, s, 0) if target.IsElf() { } else { ldr.Errorf(s, "addgotsyminternal: unsupported binary format") } }