Source file src/cmd/link/internal/arm64/asm.go

Documentation: cmd/link/internal/arm64

     1  // Inferno utils/5l/asm.c
     2  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/5l/asm.c
     3  //
     4  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
     5  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
     6  //	Portions Copyright © 1997-1999 Vita Nuova Limited
     7  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
     8  //	Portions Copyright © 2004,2006 Bruce Ellis
     9  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
    10  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
    11  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
    12  //
    13  // Permission is hereby granted, free of charge, to any person obtaining a copy
    14  // of this software and associated documentation files (the "Software"), to deal
    15  // in the Software without restriction, including without limitation the rights
    16  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    17  // copies of the Software, and to permit persons to whom the Software is
    18  // furnished to do so, subject to the following conditions:
    19  //
    20  // The above copyright notice and this permission notice shall be included in
    21  // all copies or substantial portions of the Software.
    22  //
    23  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    24  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    25  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    26  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    27  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    28  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    29  // THE SOFTWARE.
    30  
    31  package arm64
    32  
    33  import (
    34  	"cmd/internal/objabi"
    35  	"cmd/internal/sys"
    36  	"cmd/link/internal/ld"
    37  	"cmd/link/internal/loader"
    38  	"cmd/link/internal/sym"
    39  	"debug/elf"
    40  	"fmt"
    41  	"log"
    42  )
    43  
    44  func gentext(ctxt *ld.Link, ldr *loader.Loader) {
    45  	initfunc, addmoduledata := ld.PrepareAddmoduledata(ctxt)
    46  	if initfunc == nil {
    47  		return
    48  	}
    49  
    50  	o := func(op uint32) {
    51  		initfunc.AddUint32(ctxt.Arch, op)
    52  	}
    53  	// 0000000000000000 <local.dso_init>:
    54  	// 0:	90000000 	adrp	x0, 0 <runtime.firstmoduledata>
    55  	// 	0: R_AARCH64_ADR_PREL_PG_HI21	local.moduledata
    56  	// 4:	91000000 	add	x0, x0, #0x0
    57  	// 	4: R_AARCH64_ADD_ABS_LO12_NC	local.moduledata
    58  	o(0x90000000)
    59  	o(0x91000000)
    60  	rel, _ := initfunc.AddRel(objabi.R_ADDRARM64)
    61  	rel.SetOff(0)
    62  	rel.SetSiz(8)
    63  	rel.SetSym(ctxt.Moduledata)
    64  
    65  	// 8:	14000000 	b	0 <runtime.addmoduledata>
    66  	// 	8: R_AARCH64_CALL26	runtime.addmoduledata
    67  	o(0x14000000)
    68  	rel2, _ := initfunc.AddRel(objabi.R_CALLARM64)
    69  	rel2.SetOff(8)
    70  	rel2.SetSiz(4)
    71  	rel2.SetSym(addmoduledata)
    72  }
    73  
    74  func adddynrel(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym, r loader.Reloc, rIdx int) bool {
    75  	targ := r.Sym()
    76  	var targType sym.SymKind
    77  	if targ != 0 {
    78  		targType = ldr.SymType(targ)
    79  	}
    80  
    81  	const pcrel = 1
    82  	switch r.Type() {
    83  	default:
    84  		if r.Type() >= objabi.ElfRelocOffset {
    85  			ldr.Errorf(s, "unexpected relocation type %d (%s)", r.Type(), sym.RelocName(target.Arch, r.Type()))
    86  			return false
    87  		}
    88  
    89  	// Handle relocations found in ELF object files.
    90  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_PREL32):
    91  		if targType == sym.SDYNIMPORT {
    92  			ldr.Errorf(s, "unexpected R_AARCH64_PREL32 relocation for dynamic symbol %s", ldr.SymName(targ))
    93  		}
    94  		if targType == 0 || targType == sym.SXREF {
    95  			ldr.Errorf(s, "unknown symbol %s in pcrel", ldr.SymName(targ))
    96  		}
    97  		su := ldr.MakeSymbolUpdater(s)
    98  		su.SetRelocType(rIdx, objabi.R_PCREL)
    99  		su.SetRelocAdd(rIdx, r.Add()+4)
   100  		return true
   101  
   102  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_PREL64):
   103  		if targType == sym.SDYNIMPORT {
   104  			ldr.Errorf(s, "unexpected R_AARCH64_PREL64 relocation for dynamic symbol %s", ldr.SymName(targ))
   105  		}
   106  		if targType == 0 || targType == sym.SXREF {
   107  			ldr.Errorf(s, "unknown symbol %s in pcrel", ldr.SymName(targ))
   108  		}
   109  		su := ldr.MakeSymbolUpdater(s)
   110  		su.SetRelocType(rIdx, objabi.R_PCREL)
   111  		su.SetRelocAdd(rIdx, r.Add()+8)
   112  		return true
   113  
   114  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_CALL26),
   115  		objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_JUMP26):
   116  		if targType == sym.SDYNIMPORT {
   117  			addpltsym(target, ldr, syms, targ)
   118  			su := ldr.MakeSymbolUpdater(s)
   119  			su.SetRelocSym(rIdx, syms.PLT)
   120  			su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymPlt(targ)))
   121  		}
   122  		if targType == 0 || targType == sym.SXREF {
   123  			ldr.Errorf(s, "unknown symbol %s in callarm64", ldr.SymName(targ))
   124  		}
   125  		su := ldr.MakeSymbolUpdater(s)
   126  		su.SetRelocType(rIdx, objabi.R_CALLARM64)
   127  		return true
   128  
   129  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_ADR_GOT_PAGE),
   130  		objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LD64_GOT_LO12_NC):
   131  		if targType != sym.SDYNIMPORT {
   132  			// have symbol
   133  			// TODO: turn LDR of GOT entry into ADR of symbol itself
   134  		}
   135  
   136  		// fall back to using GOT
   137  		// TODO: just needs relocation, no need to put in .dynsym
   138  		ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_AARCH64_GLOB_DAT))
   139  		su := ldr.MakeSymbolUpdater(s)
   140  		su.SetRelocType(rIdx, objabi.R_ARM64_GOT)
   141  		su.SetRelocSym(rIdx, syms.GOT)
   142  		su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ)))
   143  		return true
   144  
   145  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_ADR_PREL_PG_HI21),
   146  		objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_ADD_ABS_LO12_NC):
   147  		if targType == sym.SDYNIMPORT {
   148  			ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   149  		}
   150  		if targType == 0 || targType == sym.SXREF {
   151  			ldr.Errorf(s, "unknown symbol %s", ldr.SymName(targ))
   152  		}
   153  		su := ldr.MakeSymbolUpdater(s)
   154  		su.SetRelocType(rIdx, objabi.R_ARM64_PCREL)
   155  		return true
   156  
   157  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_ABS64):
   158  		if targType == sym.SDYNIMPORT {
   159  			ldr.Errorf(s, "unexpected R_AARCH64_ABS64 relocation for dynamic symbol %s", ldr.SymName(targ))
   160  		}
   161  		su := ldr.MakeSymbolUpdater(s)
   162  		su.SetRelocType(rIdx, objabi.R_ADDR)
   163  		if target.IsPIE() && target.IsInternal() {
   164  			// For internal linking PIE, this R_ADDR relocation cannot
   165  			// be resolved statically. We need to generate a dynamic
   166  			// relocation. Let the code below handle it.
   167  			break
   168  		}
   169  		return true
   170  
   171  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST8_ABS_LO12_NC):
   172  		if targType == sym.SDYNIMPORT {
   173  			ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   174  		}
   175  		su := ldr.MakeSymbolUpdater(s)
   176  		su.SetRelocType(rIdx, objabi.R_ARM64_LDST8)
   177  		return true
   178  
   179  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST16_ABS_LO12_NC):
   180  		if targType == sym.SDYNIMPORT {
   181  			ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   182  		}
   183  		su := ldr.MakeSymbolUpdater(s)
   184  		su.SetRelocType(rIdx, objabi.R_ARM64_LDST16)
   185  		return true
   186  
   187  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST32_ABS_LO12_NC):
   188  		if targType == sym.SDYNIMPORT {
   189  			ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   190  		}
   191  		su := ldr.MakeSymbolUpdater(s)
   192  		su.SetRelocType(rIdx, objabi.R_ARM64_LDST32)
   193  		return true
   194  
   195  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST64_ABS_LO12_NC):
   196  		if targType == sym.SDYNIMPORT {
   197  			ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   198  		}
   199  		su := ldr.MakeSymbolUpdater(s)
   200  		su.SetRelocType(rIdx, objabi.R_ARM64_LDST64)
   201  
   202  		return true
   203  
   204  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST128_ABS_LO12_NC):
   205  		if targType == sym.SDYNIMPORT {
   206  			ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   207  		}
   208  		su := ldr.MakeSymbolUpdater(s)
   209  		su.SetRelocType(rIdx, objabi.R_ARM64_LDST128)
   210  		return true
   211  
   212  	// Handle relocations found in Mach-O object files.
   213  	case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_UNSIGNED*2:
   214  		if targType == sym.SDYNIMPORT {
   215  			ldr.Errorf(s, "unexpected reloc for dynamic symbol %s", ldr.SymName(targ))
   216  		}
   217  		su := ldr.MakeSymbolUpdater(s)
   218  		su.SetRelocType(rIdx, objabi.R_ADDR)
   219  		if target.IsPIE() && target.IsInternal() {
   220  			// For internal linking PIE, this R_ADDR relocation cannot
   221  			// be resolved statically. We need to generate a dynamic
   222  			// relocation. Let the code below handle it.
   223  			break
   224  		}
   225  		return true
   226  
   227  	case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_BRANCH26*2 + pcrel:
   228  		su := ldr.MakeSymbolUpdater(s)
   229  		su.SetRelocType(rIdx, objabi.R_CALLARM64)
   230  		if targType == sym.SDYNIMPORT {
   231  			addpltsym(target, ldr, syms, targ)
   232  			su.SetRelocSym(rIdx, syms.PLT)
   233  			su.SetRelocAdd(rIdx, int64(ldr.SymPlt(targ)))
   234  		}
   235  		return true
   236  
   237  	case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_PAGE21*2 + pcrel,
   238  		objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_PAGEOFF12*2:
   239  		if targType == sym.SDYNIMPORT {
   240  			ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   241  		}
   242  		su := ldr.MakeSymbolUpdater(s)
   243  		su.SetRelocType(rIdx, objabi.R_ARM64_PCREL)
   244  		return true
   245  
   246  	case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGE21*2 + pcrel,
   247  		objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12*2:
   248  		if targType != sym.SDYNIMPORT {
   249  			// have symbol
   250  			// turn MOVD sym@GOT (adrp+ldr) into MOVD $sym (adrp+add)
   251  			data := ldr.Data(s)
   252  			off := r.Off()
   253  			if int(off+3) >= len(data) {
   254  				ldr.Errorf(s, "unexpected GOT_LOAD reloc for non-dynamic symbol %s", ldr.SymName(targ))
   255  				return false
   256  			}
   257  			o := target.Arch.ByteOrder.Uint32(data[off:])
   258  			su := ldr.MakeSymbolUpdater(s)
   259  			switch {
   260  			case (o>>24)&0x9f == 0x90: // adrp
   261  				// keep instruction unchanged, change relocation type below
   262  			case o>>24 == 0xf9: // ldr
   263  				// rewrite to add
   264  				o = (0x91 << 24) | (o & (1<<22 - 1))
   265  				su.MakeWritable()
   266  				su.SetUint32(target.Arch, int64(off), o)
   267  			default:
   268  				ldr.Errorf(s, "unexpected GOT_LOAD reloc for non-dynamic symbol %s", ldr.SymName(targ))
   269  				return false
   270  			}
   271  			su.SetRelocType(rIdx, objabi.R_ARM64_PCREL)
   272  			return true
   273  		}
   274  		ld.AddGotSym(target, ldr, syms, targ, 0)
   275  		su := ldr.MakeSymbolUpdater(s)
   276  		su.SetRelocType(rIdx, objabi.R_ARM64_GOT)
   277  		su.SetRelocSym(rIdx, syms.GOT)
   278  		su.SetRelocAdd(rIdx, int64(ldr.SymGot(targ)))
   279  		return true
   280  	}
   281  
   282  	// Reread the reloc to incorporate any changes in type above.
   283  	relocs := ldr.Relocs(s)
   284  	r = relocs.At(rIdx)
   285  
   286  	switch r.Type() {
   287  	case objabi.R_CALLARM64:
   288  		if targType != sym.SDYNIMPORT {
   289  			// nothing to do, the relocation will be laid out in reloc
   290  			return true
   291  		}
   292  		if target.IsExternal() {
   293  			// External linker will do this relocation.
   294  			return true
   295  		}
   296  		// Internal linking.
   297  		if r.Add() != 0 {
   298  			ldr.Errorf(s, "PLT call with non-zero addend (%v)", r.Add())
   299  		}
   300  		// Build a PLT entry and change the relocation target to that entry.
   301  		addpltsym(target, ldr, syms, targ)
   302  		su := ldr.MakeSymbolUpdater(s)
   303  		su.SetRelocSym(rIdx, syms.PLT)
   304  		su.SetRelocAdd(rIdx, int64(ldr.SymPlt(targ)))
   305  		return true
   306  
   307  	case objabi.R_ADDRARM64:
   308  		if targType == sym.SDYNIMPORT && ldr.SymType(s) == sym.STEXT && target.IsDarwin() {
   309  			// Loading the address of a dynamic symbol. Rewrite to use GOT.
   310  			// turn MOVD $sym (adrp+add) into MOVD sym@GOT (adrp+ldr)
   311  			if r.Add() != 0 {
   312  				ldr.Errorf(s, "unexpected nonzero addend for dynamic symbol %s", ldr.SymName(targ))
   313  				return false
   314  			}
   315  			su := ldr.MakeSymbolUpdater(s)
   316  			data := ldr.Data(s)
   317  			off := r.Off()
   318  			if int(off+8) > len(data) {
   319  				ldr.Errorf(s, "unexpected R_ADDRARM64 reloc for dynamic symbol %s", ldr.SymName(targ))
   320  				return false
   321  			}
   322  			o := target.Arch.ByteOrder.Uint32(data[off+4:])
   323  			if o>>24 == 0x91 { // add
   324  				// rewrite to ldr
   325  				o = (0xf9 << 24) | 1<<22 | (o & (1<<22 - 1))
   326  				su.MakeWritable()
   327  				su.SetUint32(target.Arch, int64(off+4), o)
   328  				if target.IsInternal() {
   329  					ld.AddGotSym(target, ldr, syms, targ, 0)
   330  					su.SetRelocSym(rIdx, syms.GOT)
   331  					su.SetRelocAdd(rIdx, int64(ldr.SymGot(targ)))
   332  					su.SetRelocType(rIdx, objabi.R_ARM64_PCREL_LDST64)
   333  				} else {
   334  					su.SetRelocType(rIdx, objabi.R_ARM64_GOTPCREL)
   335  				}
   336  				return true
   337  			}
   338  			ldr.Errorf(s, "unexpected R_ADDRARM64 reloc for dynamic symbol %s", ldr.SymName(targ))
   339  		}
   340  
   341  	case objabi.R_ADDR:
   342  		if ldr.SymType(s) == sym.STEXT && target.IsElf() {
   343  			// The code is asking for the address of an external
   344  			// function. We provide it with the address of the
   345  			// correspondent GOT symbol.
   346  			ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_AARCH64_GLOB_DAT))
   347  			su := ldr.MakeSymbolUpdater(s)
   348  			su.SetRelocSym(rIdx, syms.GOT)
   349  			su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ)))
   350  			return true
   351  		}
   352  
   353  		// Process dynamic relocations for the data sections.
   354  		if target.IsPIE() && target.IsInternal() {
   355  			// When internally linking, generate dynamic relocations
   356  			// for all typical R_ADDR relocations. The exception
   357  			// are those R_ADDR that are created as part of generating
   358  			// the dynamic relocations and must be resolved statically.
   359  			//
   360  			// There are three phases relevant to understanding this:
   361  			//
   362  			//	dodata()  // we are here
   363  			//	address() // symbol address assignment
   364  			//	reloc()   // resolution of static R_ADDR relocs
   365  			//
   366  			// At this point symbol addresses have not been
   367  			// assigned yet (as the final size of the .rela section
   368  			// will affect the addresses), and so we cannot write
   369  			// the Elf64_Rela.r_offset now. Instead we delay it
   370  			// until after the 'address' phase of the linker is
   371  			// complete. We do this via Addaddrplus, which creates
   372  			// a new R_ADDR relocation which will be resolved in
   373  			// the 'reloc' phase.
   374  			//
   375  			// These synthetic static R_ADDR relocs must be skipped
   376  			// now, or else we will be caught in an infinite loop
   377  			// of generating synthetic relocs for our synthetic
   378  			// relocs.
   379  			//
   380  			// Furthermore, the rela sections contain dynamic
   381  			// relocations with R_ADDR relocations on
   382  			// Elf64_Rela.r_offset. This field should contain the
   383  			// symbol offset as determined by reloc(), not the
   384  			// final dynamically linked address as a dynamic
   385  			// relocation would provide.
   386  			switch ldr.SymName(s) {
   387  			case ".dynsym", ".rela", ".rela.plt", ".got.plt", ".dynamic":
   388  				return false
   389  			}
   390  		} else {
   391  			// Either internally linking a static executable,
   392  			// in which case we can resolve these relocations
   393  			// statically in the 'reloc' phase, or externally
   394  			// linking, in which case the relocation will be
   395  			// prepared in the 'reloc' phase and passed to the
   396  			// external linker in the 'asmb' phase.
   397  			if ldr.SymType(s) != sym.SDATA && ldr.SymType(s) != sym.SRODATA {
   398  				break
   399  			}
   400  		}
   401  
   402  		if target.IsElf() {
   403  			// Generate R_AARCH64_RELATIVE relocations for best
   404  			// efficiency in the dynamic linker.
   405  			//
   406  			// As noted above, symbol addresses have not been
   407  			// assigned yet, so we can't generate the final reloc
   408  			// entry yet. We ultimately want:
   409  			//
   410  			// r_offset = s + r.Off
   411  			// r_info = R_AARCH64_RELATIVE
   412  			// r_addend = targ + r.Add
   413  			//
   414  			// The dynamic linker will set *offset = base address +
   415  			// addend.
   416  			//
   417  			// AddAddrPlus is used for r_offset and r_addend to
   418  			// generate new R_ADDR relocations that will update
   419  			// these fields in the 'reloc' phase.
   420  			rela := ldr.MakeSymbolUpdater(syms.Rela)
   421  			rela.AddAddrPlus(target.Arch, s, int64(r.Off()))
   422  			if r.Siz() == 8 {
   423  				rela.AddUint64(target.Arch, elf.R_INFO(0, uint32(elf.R_AARCH64_RELATIVE)))
   424  			} else {
   425  				ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   426  			}
   427  			rela.AddAddrPlus(target.Arch, targ, int64(r.Add()))
   428  			// Not mark r done here. So we still apply it statically,
   429  			// so in the file content we'll also have the right offset
   430  			// to the relocation target. So it can be examined statically
   431  			// (e.g. go version).
   432  			return true
   433  		}
   434  
   435  		if target.IsDarwin() {
   436  			// Mach-O relocations are a royal pain to lay out.
   437  			// They use a compact stateful bytecode representation.
   438  			// Here we record what are needed and encode them later.
   439  			ld.MachoAddRebase(s, int64(r.Off()))
   440  			// Not mark r done here. So we still apply it statically,
   441  			// so in the file content we'll also have the right offset
   442  			// to the relocation target. So it can be examined statically
   443  			// (e.g. go version).
   444  			return true
   445  		}
   446  
   447  	case objabi.R_ARM64_GOTPCREL:
   448  		if target.IsExternal() {
   449  			// External linker will do this relocation.
   450  			return true
   451  		}
   452  		if targType != sym.SDYNIMPORT {
   453  			ldr.Errorf(s, "R_ARM64_GOTPCREL target is not SDYNIMPORT symbol: %v", ldr.SymName(targ))
   454  		}
   455  		if r.Add() != 0 {
   456  			ldr.Errorf(s, "R_ARM64_GOTPCREL with non-zero addend (%v)", r.Add())
   457  		}
   458  		if target.IsElf() {
   459  			ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_AARCH64_GLOB_DAT))
   460  		} else {
   461  			ld.AddGotSym(target, ldr, syms, targ, 0)
   462  		}
   463  		// turn into two relocations, one for each instruction.
   464  		su := ldr.MakeSymbolUpdater(s)
   465  		r.SetType(objabi.R_ARM64_GOT)
   466  		r.SetSiz(4)
   467  		r.SetSym(syms.GOT)
   468  		r.SetAdd(int64(ldr.SymGot(targ)))
   469  		r2, _ := su.AddRel(objabi.R_ARM64_GOT)
   470  		r2.SetSiz(4)
   471  		r2.SetOff(r.Off() + 4)
   472  		r2.SetSym(syms.GOT)
   473  		r2.SetAdd(int64(ldr.SymGot(targ)))
   474  		return true
   475  	}
   476  	return false
   477  }
   478  
   479  func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, ri int, sectoff int64) bool {
   480  	out.Write64(uint64(sectoff))
   481  
   482  	elfsym := ld.ElfSymForReloc(ctxt, r.Xsym)
   483  	siz := r.Size
   484  	switch r.Type {
   485  	default:
   486  		return false
   487  	case objabi.R_ADDR, objabi.R_DWARFSECREF:
   488  		switch siz {
   489  		case 4:
   490  			out.Write64(uint64(elf.R_AARCH64_ABS32) | uint64(elfsym)<<32)
   491  		case 8:
   492  			out.Write64(uint64(elf.R_AARCH64_ABS64) | uint64(elfsym)<<32)
   493  		default:
   494  			return false
   495  		}
   496  	case objabi.R_ADDRARM64:
   497  		// two relocations: R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_ADD_ABS_LO12_NC
   498  		out.Write64(uint64(elf.R_AARCH64_ADR_PREL_PG_HI21) | uint64(elfsym)<<32)
   499  		out.Write64(uint64(r.Xadd))
   500  		out.Write64(uint64(sectoff + 4))
   501  		out.Write64(uint64(elf.R_AARCH64_ADD_ABS_LO12_NC) | uint64(elfsym)<<32)
   502  
   503  	case objabi.R_ARM64_PCREL_LDST8,
   504  		objabi.R_ARM64_PCREL_LDST16,
   505  		objabi.R_ARM64_PCREL_LDST32,
   506  		objabi.R_ARM64_PCREL_LDST64:
   507  		// two relocations: R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_LDST{64/32/16/8}_ABS_LO12_NC
   508  		out.Write64(uint64(elf.R_AARCH64_ADR_PREL_PG_HI21) | uint64(elfsym)<<32)
   509  		out.Write64(uint64(r.Xadd))
   510  		out.Write64(uint64(sectoff + 4))
   511  		var ldstType elf.R_AARCH64
   512  		switch r.Type {
   513  		case objabi.R_ARM64_PCREL_LDST8:
   514  			ldstType = elf.R_AARCH64_LDST8_ABS_LO12_NC
   515  		case objabi.R_ARM64_PCREL_LDST16:
   516  			ldstType = elf.R_AARCH64_LDST16_ABS_LO12_NC
   517  		case objabi.R_ARM64_PCREL_LDST32:
   518  			ldstType = elf.R_AARCH64_LDST32_ABS_LO12_NC
   519  		case objabi.R_ARM64_PCREL_LDST64:
   520  			ldstType = elf.R_AARCH64_LDST64_ABS_LO12_NC
   521  		}
   522  		out.Write64(uint64(ldstType) | uint64(elfsym)<<32)
   523  
   524  	case objabi.R_ARM64_TLS_LE:
   525  		out.Write64(uint64(elf.R_AARCH64_TLSLE_MOVW_TPREL_G0) | uint64(elfsym)<<32)
   526  	case objabi.R_ARM64_TLS_IE:
   527  		out.Write64(uint64(elf.R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21) | uint64(elfsym)<<32)
   528  		out.Write64(uint64(r.Xadd))
   529  		out.Write64(uint64(sectoff + 4))
   530  		out.Write64(uint64(elf.R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC) | uint64(elfsym)<<32)
   531  	case objabi.R_ARM64_GOTPCREL:
   532  		out.Write64(uint64(elf.R_AARCH64_ADR_GOT_PAGE) | uint64(elfsym)<<32)
   533  		out.Write64(uint64(r.Xadd))
   534  		out.Write64(uint64(sectoff + 4))
   535  		out.Write64(uint64(elf.R_AARCH64_LD64_GOT_LO12_NC) | uint64(elfsym)<<32)
   536  	case objabi.R_CALLARM64:
   537  		if siz != 4 {
   538  			return false
   539  		}
   540  		out.Write64(uint64(elf.R_AARCH64_CALL26) | uint64(elfsym)<<32)
   541  
   542  	}
   543  	out.Write64(uint64(r.Xadd))
   544  
   545  	return true
   546  }
   547  
   548  // sign-extends from 21, 24-bit.
   549  func signext21(x int64) int64 { return x << (64 - 21) >> (64 - 21) }
   550  func signext24(x int64) int64 { return x << (64 - 24) >> (64 - 24) }
   551  
   552  func machoreloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
   553  	var v uint32
   554  
   555  	rs := r.Xsym
   556  	rt := r.Type
   557  	siz := r.Size
   558  	xadd := r.Xadd
   559  
   560  	if xadd != signext24(xadd) && rt != objabi.R_ADDR {
   561  		// If the relocation target would overflow the addend, then target
   562  		// a linker-manufactured label symbol with a smaller addend instead.
   563  		// R_ADDR has full-width addend encoded in data content, so it doesn't
   564  		// use a label symbol.
   565  		label := ldr.Lookup(offsetLabelName(ldr, rs, xadd/machoRelocLimit*machoRelocLimit), ldr.SymVersion(rs))
   566  		if label != 0 {
   567  			xadd = ldr.SymValue(rs) + xadd - ldr.SymValue(label)
   568  			rs = label
   569  		}
   570  		if xadd != signext24(xadd) {
   571  			ldr.Errorf(s, "internal error: relocation addend overflow: %s+0x%x", ldr.SymName(rs), xadd)
   572  		}
   573  	}
   574  	if rt == objabi.R_CALLARM64 && xadd != 0 {
   575  		label := ldr.Lookup(offsetLabelName(ldr, rs, xadd), ldr.SymVersion(rs))
   576  		if label != 0 {
   577  			xadd = ldr.SymValue(rs) + xadd - ldr.SymValue(label) // should always be 0 (checked below)
   578  			rs = label
   579  		}
   580  	}
   581  
   582  	if !ldr.SymType(s).IsDWARF() {
   583  		if ldr.SymDynid(rs) < 0 {
   584  			ldr.Errorf(s, "reloc %d (%s) to non-macho symbol %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymType(rs), ldr.SymType(rs))
   585  			return false
   586  		}
   587  
   588  		v = uint32(ldr.SymDynid(rs))
   589  		v |= 1 << 27 // external relocation
   590  	} else {
   591  		v = uint32(ldr.SymSect(rs).Extnum)
   592  		if v == 0 {
   593  			ldr.Errorf(s, "reloc %d (%s) to symbol %s in non-macho section %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymSect(rs).Name, ldr.SymType(rs), ldr.SymType(rs))
   594  			return false
   595  		}
   596  	}
   597  
   598  	switch rt {
   599  	default:
   600  		return false
   601  	case objabi.R_ADDR:
   602  		v |= ld.MACHO_ARM64_RELOC_UNSIGNED << 28
   603  	case objabi.R_CALLARM64:
   604  		if xadd != 0 {
   605  			// Addend should be handled above via label symbols.
   606  			ldr.Errorf(s, "unexpected non-zero addend: %s+%d", ldr.SymName(rs), xadd)
   607  		}
   608  		v |= 1 << 24 // pc-relative bit
   609  		v |= ld.MACHO_ARM64_RELOC_BRANCH26 << 28
   610  	case objabi.R_ADDRARM64,
   611  		objabi.R_ARM64_PCREL_LDST8,
   612  		objabi.R_ARM64_PCREL_LDST16,
   613  		objabi.R_ARM64_PCREL_LDST32,
   614  		objabi.R_ARM64_PCREL_LDST64:
   615  		siz = 4
   616  		// Two relocation entries: MACHO_ARM64_RELOC_PAGEOFF12 MACHO_ARM64_RELOC_PAGE21
   617  		// if r.Xadd is non-zero, add two MACHO_ARM64_RELOC_ADDEND.
   618  		if r.Xadd != 0 {
   619  			out.Write32(uint32(sectoff + 4))
   620  			out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
   621  		}
   622  		out.Write32(uint32(sectoff + 4))
   623  		out.Write32(v | (ld.MACHO_ARM64_RELOC_PAGEOFF12 << 28) | (2 << 25))
   624  		if r.Xadd != 0 {
   625  			out.Write32(uint32(sectoff))
   626  			out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
   627  		}
   628  		v |= 1 << 24 // pc-relative bit
   629  		v |= ld.MACHO_ARM64_RELOC_PAGE21 << 28
   630  	case objabi.R_ARM64_GOTPCREL:
   631  		siz = 4
   632  		// Two relocation entries: MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12 MACHO_ARM64_RELOC_GOT_LOAD_PAGE21
   633  		// if r.Xadd is non-zero, add two MACHO_ARM64_RELOC_ADDEND.
   634  		if r.Xadd != 0 {
   635  			out.Write32(uint32(sectoff + 4))
   636  			out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
   637  		}
   638  		out.Write32(uint32(sectoff + 4))
   639  		out.Write32(v | (ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12 << 28) | (2 << 25))
   640  		if r.Xadd != 0 {
   641  			out.Write32(uint32(sectoff))
   642  			out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
   643  		}
   644  		v |= 1 << 24 // pc-relative bit
   645  		v |= ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGE21 << 28
   646  	}
   647  
   648  	switch siz {
   649  	default:
   650  		return false
   651  	case 1:
   652  		v |= 0 << 25
   653  	case 2:
   654  		v |= 1 << 25
   655  	case 4:
   656  		v |= 2 << 25
   657  	case 8:
   658  		v |= 3 << 25
   659  	}
   660  
   661  	out.Write32(uint32(sectoff))
   662  	out.Write32(v)
   663  	return true
   664  }
   665  
   666  func pereloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
   667  	rs := r.Xsym
   668  	rt := r.Type
   669  
   670  	if (rt == objabi.R_ADDRARM64 || rt == objabi.R_ARM64_PCREL_LDST8 || rt == objabi.R_ARM64_PCREL_LDST16 ||
   671  		rt == objabi.R_ARM64_PCREL_LDST32 || rt == objabi.R_ARM64_PCREL_LDST64) && r.Xadd != signext21(r.Xadd) {
   672  		// If the relocation target would overflow the addend, then target
   673  		// a linker-manufactured label symbol with a smaller addend instead.
   674  		label := ldr.Lookup(offsetLabelName(ldr, rs, r.Xadd/peRelocLimit*peRelocLimit), ldr.SymVersion(rs))
   675  		if label == 0 {
   676  			ldr.Errorf(s, "invalid relocation: %v %s+0x%x", rt, ldr.SymName(rs), r.Xadd)
   677  			return false
   678  		}
   679  		rs = label
   680  	}
   681  	if rt == objabi.R_CALLARM64 && r.Xadd != 0 {
   682  		label := ldr.Lookup(offsetLabelName(ldr, rs, r.Xadd), ldr.SymVersion(rs))
   683  		if label == 0 {
   684  			ldr.Errorf(s, "invalid relocation: %v %s+0x%x", rt, ldr.SymName(rs), r.Xadd)
   685  			return false
   686  		}
   687  		rs = label
   688  	}
   689  	symdynid := ldr.SymDynid(rs)
   690  	if symdynid < 0 {
   691  		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))
   692  		return false
   693  	}
   694  
   695  	switch rt {
   696  	default:
   697  		return false
   698  
   699  	case objabi.R_DWARFSECREF:
   700  		out.Write32(uint32(sectoff))
   701  		out.Write32(uint32(symdynid))
   702  		out.Write16(ld.IMAGE_REL_ARM64_SECREL)
   703  
   704  	case objabi.R_ADDR:
   705  		out.Write32(uint32(sectoff))
   706  		out.Write32(uint32(symdynid))
   707  		if r.Size == 8 {
   708  			out.Write16(ld.IMAGE_REL_ARM64_ADDR64)
   709  		} else {
   710  			out.Write16(ld.IMAGE_REL_ARM64_ADDR32)
   711  		}
   712  
   713  	case objabi.R_PEIMAGEOFF:
   714  		out.Write16(ld.IMAGE_REL_ARM64_ADDR32NB)
   715  
   716  	case objabi.R_ADDRARM64:
   717  		// Note: r.Xadd has been taken care of below, in archreloc.
   718  		out.Write32(uint32(sectoff))
   719  		out.Write32(uint32(symdynid))
   720  		out.Write16(ld.IMAGE_REL_ARM64_PAGEBASE_REL21)
   721  
   722  		out.Write32(uint32(sectoff + 4))
   723  		out.Write32(uint32(symdynid))
   724  		out.Write16(ld.IMAGE_REL_ARM64_PAGEOFFSET_12A)
   725  
   726  	case objabi.R_ARM64_PCREL_LDST8,
   727  		objabi.R_ARM64_PCREL_LDST16,
   728  		objabi.R_ARM64_PCREL_LDST32,
   729  		objabi.R_ARM64_PCREL_LDST64:
   730  		// Note: r.Xadd has been taken care of below, in archreloc.
   731  		out.Write32(uint32(sectoff))
   732  		out.Write32(uint32(symdynid))
   733  		out.Write16(ld.IMAGE_REL_ARM64_PAGEBASE_REL21)
   734  
   735  		out.Write32(uint32(sectoff + 4))
   736  		out.Write32(uint32(symdynid))
   737  		out.Write16(ld.IMAGE_REL_ARM64_PAGEOFFSET_12L)
   738  
   739  	case objabi.R_CALLARM64:
   740  		// Note: r.Xadd has been taken care of above, by using a label pointing into the middle of the function.
   741  		out.Write32(uint32(sectoff))
   742  		out.Write32(uint32(symdynid))
   743  		out.Write16(ld.IMAGE_REL_ARM64_BRANCH26)
   744  	}
   745  
   746  	return true
   747  }
   748  
   749  func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loader.Reloc, s loader.Sym, val int64) (int64, int, bool) {
   750  	const noExtReloc = 0
   751  	const isOk = true
   752  
   753  	rs := r.Sym()
   754  
   755  	if target.IsExternal() {
   756  		nExtReloc := 0
   757  		switch rt := r.Type(); rt {
   758  		default:
   759  		case objabi.R_ARM64_GOTPCREL,
   760  			objabi.R_ARM64_PCREL_LDST8,
   761  			objabi.R_ARM64_PCREL_LDST16,
   762  			objabi.R_ARM64_PCREL_LDST32,
   763  			objabi.R_ARM64_PCREL_LDST64,
   764  			objabi.R_ADDRARM64:
   765  
   766  			// set up addend for eventual relocation via outer symbol.
   767  			rs, off := ld.FoldSubSymbolOffset(ldr, rs)
   768  			xadd := r.Add() + off
   769  			rst := ldr.SymType(rs)
   770  			if rst != sym.SHOSTOBJ && rst != sym.SDYNIMPORT && ldr.SymSect(rs) == nil {
   771  				ldr.Errorf(s, "missing section for %s", ldr.SymName(rs))
   772  			}
   773  
   774  			nExtReloc = 2 // need two ELF/Mach-O relocations. see elfreloc1/machoreloc1
   775  			if target.IsDarwin() && xadd != 0 {
   776  				nExtReloc = 4 // need another two relocations for non-zero addend
   777  			}
   778  
   779  			if target.IsWindows() {
   780  				var o0, o1 uint32
   781  				if target.IsBigEndian() {
   782  					o0 = uint32(val >> 32)
   783  					o1 = uint32(val)
   784  				} else {
   785  					o0 = uint32(val)
   786  					o1 = uint32(val >> 32)
   787  				}
   788  
   789  				// The first instruction (ADRP) has a 21-bit immediate field,
   790  				// and the second (ADD or LD/ST) has a 12-bit immediate field.
   791  				// The first instruction is only for high bits, but to get the carry bits right we have
   792  				// to put the full addend, including the bottom 12 bits again.
   793  				// That limits the distance of any addend to only 21 bits.
   794  				// But we assume that ADRP's top bit will be interpreted as a sign bit,
   795  				// so we only use 20 bits.
   796  				// pereloc takes care of introducing new symbol labels
   797  				// every megabyte for longer relocations.
   798  				xadd := uint32(xadd)
   799  				o0 |= (xadd&3)<<29 | (xadd&0xffffc)<<3
   800  				switch rt {
   801  				case objabi.R_ARM64_PCREL_LDST8, objabi.R_ADDRARM64:
   802  					o1 |= (xadd & 0xfff) << 10
   803  				case objabi.R_ARM64_PCREL_LDST16:
   804  					if xadd&0x1 != 0 {
   805  						ldr.Errorf(s, "offset for 16-bit load/store has unaligned value %d", xadd&0xfff)
   806  					}
   807  					o1 |= ((xadd & 0xfff) >> 1) << 10
   808  				case objabi.R_ARM64_PCREL_LDST32:
   809  					if xadd&0x3 != 0 {
   810  						ldr.Errorf(s, "offset for 32-bit load/store has unaligned value %d", xadd&0xfff)
   811  					}
   812  					o1 |= ((xadd & 0xfff) >> 2) << 10
   813  				case objabi.R_ARM64_PCREL_LDST64:
   814  					if xadd&0x7 != 0 {
   815  						ldr.Errorf(s, "offset for 64-bit load/store has unaligned value %d", xadd&0xfff)
   816  					}
   817  					o1 |= ((xadd & 0xfff) >> 3) << 10
   818  				}
   819  
   820  				if target.IsBigEndian() {
   821  					val = int64(o0)<<32 | int64(o1)
   822  				} else {
   823  					val = int64(o1)<<32 | int64(o0)
   824  				}
   825  			}
   826  
   827  			return val, nExtReloc, isOk
   828  
   829  		case objabi.R_CALLARM64:
   830  			nExtReloc = 1
   831  			return val, nExtReloc, isOk
   832  
   833  		case objabi.R_ARM64_TLS_LE:
   834  			nExtReloc = 1
   835  			return val, nExtReloc, isOk
   836  
   837  		case objabi.R_ARM64_TLS_IE:
   838  			nExtReloc = 2 // need two ELF relocations. see elfreloc1
   839  			return val, nExtReloc, isOk
   840  
   841  		case objabi.R_ADDR:
   842  			if target.IsWindows() && r.Add() != 0 {
   843  				if r.Siz() == 8 {
   844  					val = r.Add()
   845  				} else if target.IsBigEndian() {
   846  					val = int64(uint32(val)) | int64(r.Add())<<32
   847  				} else {
   848  					val = val>>32<<32 | int64(uint32(r.Add()))
   849  				}
   850  				return val, 1, true
   851  			}
   852  		}
   853  	}
   854  
   855  	switch rt := r.Type(); rt {
   856  	case objabi.R_ADDRARM64,
   857  		objabi.R_ARM64_PCREL_LDST8,
   858  		objabi.R_ARM64_PCREL_LDST16,
   859  		objabi.R_ARM64_PCREL_LDST32,
   860  		objabi.R_ARM64_PCREL_LDST64:
   861  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
   862  		if t >= 1<<32 || t < -1<<32 {
   863  			ldr.Errorf(s, "program too large, address relocation distance = %d", t)
   864  		}
   865  
   866  		var o0, o1 uint32
   867  
   868  		if target.IsBigEndian() {
   869  			o0 = uint32(val >> 32)
   870  			o1 = uint32(val)
   871  		} else {
   872  			o0 = uint32(val)
   873  			o1 = uint32(val >> 32)
   874  		}
   875  
   876  		o0 |= (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
   877  		switch rt {
   878  		case objabi.R_ARM64_PCREL_LDST8, objabi.R_ADDRARM64:
   879  			o1 |= uint32(t&0xfff) << 10
   880  		case objabi.R_ARM64_PCREL_LDST16:
   881  			if t&0x1 != 0 {
   882  				ldr.Errorf(s, "offset for 16-bit load/store has unaligned value %d", t&0xfff)
   883  			}
   884  			o1 |= (uint32(t&0xfff) >> 1) << 10
   885  		case objabi.R_ARM64_PCREL_LDST32:
   886  			if t&0x3 != 0 {
   887  				ldr.Errorf(s, "offset for 32-bit load/store has unaligned value %d", t&0xfff)
   888  			}
   889  			o1 |= (uint32(t&0xfff) >> 2) << 10
   890  		case objabi.R_ARM64_PCREL_LDST64:
   891  			if t&0x7 != 0 {
   892  				ldr.Errorf(s, "offset for 64-bit load/store has unaligned value %d", t&0xfff)
   893  			}
   894  			o1 |= (uint32(t&0xfff) >> 3) << 10
   895  		}
   896  
   897  		// when laid out, the instruction order must always be o1, o2.
   898  		if target.IsBigEndian() {
   899  			return int64(o0)<<32 | int64(o1), noExtReloc, true
   900  		}
   901  		return int64(o1)<<32 | int64(o0), noExtReloc, true
   902  
   903  	case objabi.R_ARM64_TLS_LE:
   904  		if target.IsDarwin() {
   905  			ldr.Errorf(s, "TLS reloc on unsupported OS %v", target.HeadType)
   906  		}
   907  		// The TCB is two pointers. This is not documented anywhere, but is
   908  		// de facto part of the ABI.
   909  		v := ldr.SymValue(rs) + int64(2*target.Arch.PtrSize)
   910  		if v < 0 || v >= 32678 {
   911  			ldr.Errorf(s, "TLS offset out of range %d", v)
   912  		}
   913  		return val | (v << 5), noExtReloc, true
   914  
   915  	case objabi.R_ARM64_TLS_IE:
   916  		if target.IsPIE() && target.IsElf() {
   917  			// We are linking the final executable, so we
   918  			// can optimize any TLS IE relocation to LE.
   919  
   920  			if !target.IsLinux() {
   921  				ldr.Errorf(s, "TLS reloc on unsupported OS %v", target.HeadType)
   922  			}
   923  
   924  			// The TCB is two pointers. This is not documented anywhere, but is
   925  			// de facto part of the ABI.
   926  			v := ldr.SymAddr(rs) + int64(2*target.Arch.PtrSize) + r.Add()
   927  			if v < 0 || v >= 32678 {
   928  				ldr.Errorf(s, "TLS offset out of range %d", v)
   929  			}
   930  
   931  			var o0, o1 uint32
   932  			if target.IsBigEndian() {
   933  				o0 = uint32(val >> 32)
   934  				o1 = uint32(val)
   935  			} else {
   936  				o0 = uint32(val)
   937  				o1 = uint32(val >> 32)
   938  			}
   939  
   940  			// R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21
   941  			// turn ADRP to MOVZ
   942  			o0 = 0xd2a00000 | uint32(o0&0x1f) | (uint32((v>>16)&0xffff) << 5)
   943  			// R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC
   944  			// turn LD64 to MOVK
   945  			if v&3 != 0 {
   946  				ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC", v)
   947  			}
   948  			o1 = 0xf2800000 | uint32(o1&0x1f) | (uint32(v&0xffff) << 5)
   949  
   950  			// when laid out, the instruction order must always be o0, o1.
   951  			if target.IsBigEndian() {
   952  				return int64(o0)<<32 | int64(o1), noExtReloc, isOk
   953  			}
   954  			return int64(o1)<<32 | int64(o0), noExtReloc, isOk
   955  		} else {
   956  			log.Fatalf("cannot handle R_ARM64_TLS_IE (sym %s) when linking internally", ldr.SymName(s))
   957  		}
   958  
   959  	case objabi.R_CALLARM64:
   960  		var t int64
   961  		if ldr.SymType(rs) == sym.SDYNIMPORT {
   962  			t = (ldr.SymAddr(syms.PLT) + r.Add()) - (ldr.SymValue(s) + int64(r.Off()))
   963  		} else {
   964  			t = (ldr.SymAddr(rs) + r.Add()) - (ldr.SymValue(s) + int64(r.Off()))
   965  		}
   966  		if t >= 1<<27 || t < -1<<27 {
   967  			ldr.Errorf(s, "program too large, call relocation distance = %d", t)
   968  		}
   969  		return val | ((t >> 2) & 0x03ffffff), noExtReloc, true
   970  
   971  	case objabi.R_ARM64_GOT:
   972  		if (val>>24)&0x9f == 0x90 {
   973  			// R_AARCH64_ADR_GOT_PAGE
   974  			// patch instruction: adrp
   975  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
   976  			if t >= 1<<32 || t < -1<<32 {
   977  				ldr.Errorf(s, "program too large, address relocation distance = %d", t)
   978  			}
   979  			var o0 uint32
   980  			o0 |= (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
   981  			return val | int64(o0), noExtReloc, isOk
   982  		} else if val>>24 == 0xf9 {
   983  			// R_AARCH64_LD64_GOT_LO12_NC
   984  			// patch instruction: ldr
   985  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
   986  			if t&7 != 0 {
   987  				ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LD64_GOT_LO12_NC", t)
   988  			}
   989  			var o1 uint32
   990  			o1 |= uint32(t&0xfff) << (10 - 3)
   991  			return val | int64(uint64(o1)), noExtReloc, isOk
   992  		} else {
   993  			ldr.Errorf(s, "unsupported instruction for %x R_GOTARM64", val)
   994  		}
   995  
   996  	case objabi.R_ARM64_PCREL:
   997  		if (val>>24)&0x9f == 0x90 {
   998  			// R_AARCH64_ADR_PREL_PG_HI21
   999  			// patch instruction: adrp
  1000  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1001  			if t >= 1<<32 || t < -1<<32 {
  1002  				ldr.Errorf(s, "program too large, address relocation distance = %d", t)
  1003  			}
  1004  			o0 := (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
  1005  			return val | int64(o0), noExtReloc, isOk
  1006  		} else if (val>>24)&0x9f == 0x91 {
  1007  			// ELF R_AARCH64_ADD_ABS_LO12_NC or Mach-O ARM64_RELOC_PAGEOFF12
  1008  			// patch instruction: add
  1009  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1010  			o1 := uint32(t&0xfff) << 10
  1011  			return val | int64(o1), noExtReloc, isOk
  1012  		} else if (val>>24)&0x3b == 0x39 {
  1013  			// Mach-O ARM64_RELOC_PAGEOFF12
  1014  			// patch ldr/str(b/h/w/d/q) (integer or vector) instructions, which have different scaling factors.
  1015  			// Mach-O uses same relocation type for them.
  1016  			shift := uint32(val) >> 30
  1017  			if shift == 0 && (val>>20)&0x048 == 0x048 { // 128-bit vector load
  1018  				shift = 4
  1019  			}
  1020  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1021  			if t&(1<<shift-1) != 0 {
  1022  				ldr.Errorf(s, "invalid address: %x for relocation type: ARM64_RELOC_PAGEOFF12", t)
  1023  			}
  1024  			o1 := (uint32(t&0xfff) >> shift) << 10
  1025  			return val | int64(o1), noExtReloc, isOk
  1026  		} else {
  1027  			ldr.Errorf(s, "unsupported instruction for %x R_ARM64_PCREL", val)
  1028  		}
  1029  
  1030  	case objabi.R_ARM64_LDST8:
  1031  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1032  		o0 := uint32(t&0xfff) << 10
  1033  		return val | int64(o0), noExtReloc, true
  1034  
  1035  	case objabi.R_ARM64_LDST16:
  1036  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1037  		if t&1 != 0 {
  1038  			ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST16_ABS_LO12_NC", t)
  1039  		}
  1040  		o0 := (uint32(t&0xfff) >> 1) << 10
  1041  		return val | int64(o0), noExtReloc, true
  1042  
  1043  	case objabi.R_ARM64_LDST32:
  1044  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1045  		if t&3 != 0 {
  1046  			ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST32_ABS_LO12_NC", t)
  1047  		}
  1048  		o0 := (uint32(t&0xfff) >> 2) << 10
  1049  		return val | int64(o0), noExtReloc, true
  1050  
  1051  	case objabi.R_ARM64_LDST64:
  1052  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1053  		if t&7 != 0 {
  1054  			ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST64_ABS_LO12_NC", t)
  1055  		}
  1056  		o0 := (uint32(t&0xfff) >> 3) << 10
  1057  		return val | int64(o0), noExtReloc, true
  1058  
  1059  	case objabi.R_ARM64_LDST128:
  1060  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1061  		if t&15 != 0 {
  1062  			ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST128_ABS_LO12_NC", t)
  1063  		}
  1064  		o0 := (uint32(t&0xfff) >> 4) << 10
  1065  		return val | int64(o0), noExtReloc, true
  1066  	}
  1067  
  1068  	return val, 0, false
  1069  }
  1070  
  1071  func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
  1072  	log.Fatalf("unexpected relocation variant")
  1073  	return -1
  1074  }
  1075  
  1076  func extreloc(target *ld.Target, ldr *loader.Loader, r loader.Reloc, s loader.Sym) (loader.ExtReloc, bool) {
  1077  	switch rt := r.Type(); rt {
  1078  	case objabi.R_ARM64_GOTPCREL,
  1079  		objabi.R_ARM64_PCREL_LDST8,
  1080  		objabi.R_ARM64_PCREL_LDST16,
  1081  		objabi.R_ARM64_PCREL_LDST32,
  1082  		objabi.R_ARM64_PCREL_LDST64,
  1083  		objabi.R_ADDRARM64:
  1084  		rr := ld.ExtrelocViaOuterSym(ldr, r, s)
  1085  		return rr, true
  1086  	case objabi.R_CALLARM64,
  1087  		objabi.R_ARM64_TLS_LE,
  1088  		objabi.R_ARM64_TLS_IE:
  1089  		return ld.ExtrelocSimple(ldr, r), true
  1090  	}
  1091  	return loader.ExtReloc{}, false
  1092  }
  1093  
  1094  func elfsetupplt(ctxt *ld.Link, ldr *loader.Loader, plt, gotplt *loader.SymbolBuilder, dynamic loader.Sym) {
  1095  	if plt.Size() == 0 {
  1096  		// stp     x16, x30, [sp, #-16]!
  1097  		// identifying information
  1098  		plt.AddUint32(ctxt.Arch, 0xa9bf7bf0)
  1099  
  1100  		// the following two instructions (adrp + ldr) load *got[2] into x17
  1101  		// adrp    x16, &got[0]
  1102  		plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_GOT, 4)
  1103  		plt.SetUint32(ctxt.Arch, plt.Size()-4, 0x90000010)
  1104  
  1105  		// <imm> is the offset value of &got[2] to &got[0], the same below
  1106  		// ldr     x17, [x16, <imm>]
  1107  		plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_GOT, 4)
  1108  		plt.SetUint32(ctxt.Arch, plt.Size()-4, 0xf9400211)
  1109  
  1110  		// add     x16, x16, <imm>
  1111  		plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_PCREL, 4)
  1112  		plt.SetUint32(ctxt.Arch, plt.Size()-4, 0x91000210)
  1113  
  1114  		// br      x17
  1115  		plt.AddUint32(ctxt.Arch, 0xd61f0220)
  1116  
  1117  		// 3 nop for place holder
  1118  		plt.AddUint32(ctxt.Arch, 0xd503201f)
  1119  		plt.AddUint32(ctxt.Arch, 0xd503201f)
  1120  		plt.AddUint32(ctxt.Arch, 0xd503201f)
  1121  
  1122  		// check gotplt.size == 0
  1123  		if gotplt.Size() != 0 {
  1124  			ctxt.Errorf(gotplt.Sym(), "got.plt is not empty at the very beginning")
  1125  		}
  1126  		gotplt.AddAddrPlus(ctxt.Arch, dynamic, 0)
  1127  
  1128  		gotplt.AddUint64(ctxt.Arch, 0)
  1129  		gotplt.AddUint64(ctxt.Arch, 0)
  1130  	}
  1131  }
  1132  
  1133  func addpltsym(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym) {
  1134  	if ldr.SymPlt(s) >= 0 {
  1135  		return
  1136  	}
  1137  
  1138  	ld.Adddynsym(ldr, target, syms, s)
  1139  
  1140  	if target.IsElf() {
  1141  		plt := ldr.MakeSymbolUpdater(syms.PLT)
  1142  		gotplt := ldr.MakeSymbolUpdater(syms.GOTPLT)
  1143  		rela := ldr.MakeSymbolUpdater(syms.RelaPLT)
  1144  		if plt.Size() == 0 {
  1145  			panic("plt is not set up")
  1146  		}
  1147  
  1148  		// adrp    x16, &got.plt[0]
  1149  		plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
  1150  		plt.SetUint32(target.Arch, plt.Size()-4, 0x90000010)
  1151  		relocs := plt.Relocs()
  1152  		plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_GOT)
  1153  
  1154  		// <offset> is the offset value of &got.plt[n] to &got.plt[0]
  1155  		// ldr     x17, [x16, <offset>]
  1156  		plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
  1157  		plt.SetUint32(target.Arch, plt.Size()-4, 0xf9400211)
  1158  		relocs = plt.Relocs()
  1159  		plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_GOT)
  1160  
  1161  		// add     x16, x16, <offset>
  1162  		plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
  1163  		plt.SetUint32(target.Arch, plt.Size()-4, 0x91000210)
  1164  		relocs = plt.Relocs()
  1165  		plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_PCREL)
  1166  
  1167  		// br      x17
  1168  		plt.AddUint32(target.Arch, 0xd61f0220)
  1169  
  1170  		// add to got.plt: pointer to plt[0]
  1171  		gotplt.AddAddrPlus(target.Arch, plt.Sym(), 0)
  1172  
  1173  		// rela
  1174  		rela.AddAddrPlus(target.Arch, gotplt.Sym(), gotplt.Size()-8)
  1175  		sDynid := ldr.SymDynid(s)
  1176  
  1177  		rela.AddUint64(target.Arch, elf.R_INFO(uint32(sDynid), uint32(elf.R_AARCH64_JUMP_SLOT)))
  1178  		rela.AddUint64(target.Arch, 0)
  1179  
  1180  		ldr.SetPlt(s, int32(plt.Size()-16))
  1181  	} else if target.IsDarwin() {
  1182  		ld.AddGotSym(target, ldr, syms, s, 0)
  1183  
  1184  		sDynid := ldr.SymDynid(s)
  1185  		lep := ldr.MakeSymbolUpdater(syms.LinkEditPLT)
  1186  		lep.AddUint32(target.Arch, uint32(sDynid))
  1187  
  1188  		plt := ldr.MakeSymbolUpdater(syms.PLT)
  1189  		ldr.SetPlt(s, int32(plt.Size()))
  1190  
  1191  		// adrp x16, GOT
  1192  		plt.AddUint32(target.Arch, 0x90000010)
  1193  		r, _ := plt.AddRel(objabi.R_ARM64_GOT)
  1194  		r.SetOff(int32(plt.Size() - 4))
  1195  		r.SetSiz(4)
  1196  		r.SetSym(syms.GOT)
  1197  		r.SetAdd(int64(ldr.SymGot(s)))
  1198  
  1199  		// ldr x17, [x16, <offset>]
  1200  		plt.AddUint32(target.Arch, 0xf9400211)
  1201  		r, _ = plt.AddRel(objabi.R_ARM64_GOT)
  1202  		r.SetOff(int32(plt.Size() - 4))
  1203  		r.SetSiz(4)
  1204  		r.SetSym(syms.GOT)
  1205  		r.SetAdd(int64(ldr.SymGot(s)))
  1206  
  1207  		// br x17
  1208  		plt.AddUint32(target.Arch, 0xd61f0220)
  1209  	} else {
  1210  		ldr.Errorf(s, "addpltsym: unsupported binary format")
  1211  	}
  1212  }
  1213  
  1214  const (
  1215  	machoRelocLimit = 1 << 23
  1216  	peRelocLimit    = 1 << 20
  1217  )
  1218  
  1219  func gensymlate(ctxt *ld.Link, ldr *loader.Loader) {
  1220  	// When external linking on darwin, Mach-O relocation has only signed 24-bit
  1221  	// addend. For large symbols, we generate "label" symbols in the middle, so
  1222  	// that relocations can target them with smaller addends.
  1223  	// On Windows, we only get 21 bits, again (presumably) signed.
  1224  	// Also, on Windows (always) and Darwin (for very large binaries), the external
  1225  	// linker doesn't support CALL relocations with addend, so we generate "label"
  1226  	// symbols for functions of which we can target the middle (Duff's devices).
  1227  	if !ctxt.IsDarwin() && !ctxt.IsWindows() || !ctxt.IsExternal() {
  1228  		return
  1229  	}
  1230  
  1231  	limit := int64(machoRelocLimit)
  1232  	if ctxt.IsWindows() {
  1233  		limit = peRelocLimit
  1234  	}
  1235  
  1236  	// addLabelSyms adds "label" symbols at s+limit, s+2*limit, etc.
  1237  	addLabelSyms := func(s loader.Sym, limit, sz int64) {
  1238  		v := ldr.SymValue(s)
  1239  		for off := limit; off < sz; off += limit {
  1240  			p := ldr.LookupOrCreateSym(offsetLabelName(ldr, s, off), ldr.SymVersion(s))
  1241  			ldr.SetAttrReachable(p, true)
  1242  			ldr.SetSymValue(p, v+off)
  1243  			ldr.SetSymSect(p, ldr.SymSect(s))
  1244  			if ctxt.IsDarwin() {
  1245  				ld.AddMachoSym(ldr, p)
  1246  			} else if ctxt.IsWindows() {
  1247  				ld.AddPELabelSym(ldr, p)
  1248  			} else {
  1249  				panic("missing case in gensymlate")
  1250  			}
  1251  			// fmt.Printf("gensymlate %s %x\n", ldr.SymName(p), ldr.SymValue(p))
  1252  		}
  1253  	}
  1254  
  1255  	// Generate symbol names for every offset we need in duffcopy/duffzero (only 64 each).
  1256  	if s := ldr.Lookup("runtime.duffcopy", sym.SymVerABIInternal); s != 0 && ldr.AttrReachable(s) {
  1257  		addLabelSyms(s, 8, 8*64)
  1258  	}
  1259  	if s := ldr.Lookup("runtime.duffzero", sym.SymVerABIInternal); s != 0 && ldr.AttrReachable(s) {
  1260  		addLabelSyms(s, 4, 4*64)
  1261  	}
  1262  
  1263  	if ctxt.IsDarwin() {
  1264  		big := false
  1265  		for _, seg := range ld.Segments {
  1266  			if seg.Length >= machoRelocLimit {
  1267  				big = true
  1268  				break
  1269  			}
  1270  		}
  1271  		if !big {
  1272  			return // skip work if nothing big
  1273  		}
  1274  	}
  1275  
  1276  	for s, n := loader.Sym(1), loader.Sym(ldr.NSym()); s < n; s++ {
  1277  		if !ldr.AttrReachable(s) {
  1278  			continue
  1279  		}
  1280  		t := ldr.SymType(s)
  1281  		if t == sym.STEXT {
  1282  			// Except for Duff's devices (handled above), we don't
  1283  			// target the middle of a function.
  1284  			continue
  1285  		}
  1286  		if t >= sym.SDWARFSECT {
  1287  			continue // no need to add label for DWARF symbols
  1288  		}
  1289  		sz := ldr.SymSize(s)
  1290  		if sz <= limit {
  1291  			continue
  1292  		}
  1293  		addLabelSyms(s, limit, sz)
  1294  	}
  1295  
  1296  	// Also for carrier symbols (for which SymSize is 0)
  1297  	for _, ss := range ld.CarrierSymByType {
  1298  		if ss.Sym != 0 && ss.Size > limit {
  1299  			addLabelSyms(ss.Sym, limit, ss.Size)
  1300  		}
  1301  	}
  1302  }
  1303  
  1304  // offsetLabelName returns the name of the "label" symbol used for a
  1305  // relocation targeting s+off. The label symbols is used on Darwin/Windows
  1306  // when external linking, so that the addend fits in a Mach-O/PE relocation.
  1307  func offsetLabelName(ldr *loader.Loader, s loader.Sym, off int64) string {
  1308  	if off>>20<<20 == off {
  1309  		return fmt.Sprintf("%s+%dMB", ldr.SymExtname(s), off>>20)
  1310  	}
  1311  	return fmt.Sprintf("%s+%d", ldr.SymExtname(s), off)
  1312  }
  1313  
  1314  // Convert the direct jump relocation r to refer to a trampoline if the target is too far.
  1315  func trampoline(ctxt *ld.Link, ldr *loader.Loader, ri int, rs, s loader.Sym) {
  1316  	relocs := ldr.Relocs(s)
  1317  	r := relocs.At(ri)
  1318  	const pcrel = 1
  1319  	switch r.Type() {
  1320  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_CALL26),
  1321  		objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_JUMP26),
  1322  		objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_BRANCH26*2 + pcrel:
  1323  		// Host object relocations that will be turned into a PLT call.
  1324  		// The PLT may be too far. Insert a trampoline for them.
  1325  		fallthrough
  1326  	case objabi.R_CALLARM64:
  1327  		var t int64
  1328  		// ldr.SymValue(rs) == 0 indicates a cross-package jump to a function that is not yet
  1329  		// laid out. Conservatively use a trampoline. This should be rare, as we lay out packages
  1330  		// in dependency order.
  1331  		if ldr.SymValue(rs) != 0 {
  1332  			t = ldr.SymValue(rs) + r.Add() - (ldr.SymValue(s) + int64(r.Off()))
  1333  		}
  1334  		if t >= 1<<27 || t < -1<<27 || ldr.SymValue(rs) == 0 || (*ld.FlagDebugTramp > 1 && (ldr.SymPkg(s) == "" || ldr.SymPkg(s) != ldr.SymPkg(rs))) {
  1335  			// direct call too far, need to insert trampoline.
  1336  			// look up existing trampolines first. if we found one within the range
  1337  			// of direct call, we can reuse it. otherwise create a new one.
  1338  			var tramp loader.Sym
  1339  			for i := 0; ; i++ {
  1340  				oName := ldr.SymName(rs)
  1341  				name := oName + fmt.Sprintf("%+x-tramp%d", r.Add(), i)
  1342  				tramp = ldr.LookupOrCreateSym(name, int(ldr.SymVersion(rs)))
  1343  				ldr.SetAttrReachable(tramp, true)
  1344  				if ldr.SymType(tramp) == sym.SDYNIMPORT {
  1345  					// don't reuse trampoline defined in other module
  1346  					continue
  1347  				}
  1348  				if oName == "runtime.deferreturn" {
  1349  					ldr.SetIsDeferReturnTramp(tramp, true)
  1350  				}
  1351  				if ldr.SymValue(tramp) == 0 {
  1352  					// either the trampoline does not exist -- we need to create one,
  1353  					// or found one the address which is not assigned -- this will be
  1354  					// laid down immediately after the current function. use this one.
  1355  					break
  1356  				}
  1357  
  1358  				t = ldr.SymValue(tramp) - (ldr.SymValue(s) + int64(r.Off()))
  1359  				if t >= -1<<27 && t < 1<<27 {
  1360  					// found an existing trampoline that is not too far
  1361  					// we can just use it
  1362  					break
  1363  				}
  1364  			}
  1365  			if ldr.SymType(tramp) == 0 {
  1366  				// trampoline does not exist, create one
  1367  				trampb := ldr.MakeSymbolUpdater(tramp)
  1368  				ctxt.AddTramp(trampb)
  1369  				if ldr.SymType(rs) == sym.SDYNIMPORT {
  1370  					if r.Add() != 0 {
  1371  						ctxt.Errorf(s, "nonzero addend for DYNIMPORT call: %v+%d", ldr.SymName(rs), r.Add())
  1372  					}
  1373  					gentrampgot(ctxt, ldr, trampb, rs)
  1374  				} else {
  1375  					gentramp(ctxt, ldr, trampb, rs, r.Add())
  1376  				}
  1377  			}
  1378  			// modify reloc to point to tramp, which will be resolved later
  1379  			sb := ldr.MakeSymbolUpdater(s)
  1380  			relocs := sb.Relocs()
  1381  			r := relocs.At(ri)
  1382  			r.SetSym(tramp)
  1383  			r.SetAdd(0) // clear the offset embedded in the instruction
  1384  		}
  1385  	default:
  1386  		ctxt.Errorf(s, "trampoline called with non-jump reloc: %d (%s)", r.Type(), sym.RelocName(ctxt.Arch, r.Type()))
  1387  	}
  1388  }
  1389  
  1390  // generate a trampoline to target+offset.
  1391  func gentramp(ctxt *ld.Link, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) {
  1392  	tramp.SetSize(12) // 3 instructions
  1393  	P := make([]byte, tramp.Size())
  1394  	o1 := uint32(0x90000010) // adrp x16, target
  1395  	o2 := uint32(0x91000210) // add x16, pc-relative-offset
  1396  	o3 := uint32(0xd61f0200) // br x16
  1397  	ctxt.Arch.ByteOrder.PutUint32(P, o1)
  1398  	ctxt.Arch.ByteOrder.PutUint32(P[4:], o2)
  1399  	ctxt.Arch.ByteOrder.PutUint32(P[8:], o3)
  1400  	tramp.SetData(P)
  1401  
  1402  	r, _ := tramp.AddRel(objabi.R_ADDRARM64)
  1403  	r.SetSiz(8)
  1404  	r.SetSym(target)
  1405  	r.SetAdd(offset)
  1406  }
  1407  
  1408  // generate a trampoline to target+offset for a DYNIMPORT symbol via GOT.
  1409  func gentrampgot(ctxt *ld.Link, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym) {
  1410  	tramp.SetSize(12) // 3 instructions
  1411  	P := make([]byte, tramp.Size())
  1412  	o1 := uint32(0x90000010) // adrp x16, target@GOT
  1413  	o2 := uint32(0xf9400210) // ldr x16, [x16, offset]
  1414  	o3 := uint32(0xd61f0200) // br x16
  1415  	ctxt.Arch.ByteOrder.PutUint32(P, o1)
  1416  	ctxt.Arch.ByteOrder.PutUint32(P[4:], o2)
  1417  	ctxt.Arch.ByteOrder.PutUint32(P[8:], o3)
  1418  	tramp.SetData(P)
  1419  
  1420  	r, _ := tramp.AddRel(objabi.R_ARM64_GOTPCREL)
  1421  	r.SetSiz(8)
  1422  	r.SetSym(target)
  1423  }
  1424  

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