| // 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 <local.dso_init>: |
| // 0: e59f0004 ldr r0, [pc, #4] ; c <local.dso_init+0xc> |
| // 4: e5900000 ldr r0, [r0] |
| // 8: eafffffe b 0 <runtime.addmoduledata> |
| // 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, 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 |
| } |
| |
| 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 { |
| // 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") |
| } |
| } |
