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

     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_SUBTRACTOR*2:
   228  		// ARM64_RELOC_SUBTRACTOR must be followed by ARM64_RELOC_UNSIGNED.
   229  		// The pair of relocations resolves to the difference between two
   230  		// symbol addresses (each relocation specifies a symbol).
   231  		outer, off := ld.FoldSubSymbolOffset(ldr, targ)
   232  		if outer != s {
   233  			// TODO: support subtracted symbol in different section.
   234  			ldr.Errorf(s, "unsupported ARM64_RELOC_SUBTRACTOR reloc: target %s, outer %s", ldr.SymName(targ), ldr.SymName(outer))
   235  			break
   236  		}
   237  		su := ldr.MakeSymbolUpdater(s)
   238  		relocs := su.Relocs()
   239  		if rIdx+1 >= relocs.Count() || relocs.At(rIdx+1).Type() != objabi.MachoRelocOffset+ld.MACHO_ARM64_RELOC_UNSIGNED*2 || relocs.At(rIdx+1).Off() != r.Off() {
   240  			ldr.Errorf(s, "unexpected ARM64_RELOC_SUBTRACTOR reloc, must be followed by ARM64_RELOC_UNSIGNED at same offset")
   241  			break
   242  		}
   243  		su.SetRelocType(rIdx+1, objabi.R_PCREL)
   244  		su.SetRelocAdd(rIdx+1, r.Add()+int64(r.Off())+int64(r.Siz())-off)
   245  		// Remove the other relocation
   246  		su.SetRelocSiz(rIdx, 0)
   247  		return true
   248  
   249  	case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_BRANCH26*2 + pcrel:
   250  		su := ldr.MakeSymbolUpdater(s)
   251  		su.SetRelocType(rIdx, objabi.R_CALLARM64)
   252  		if targType == sym.SDYNIMPORT {
   253  			addpltsym(target, ldr, syms, targ)
   254  			su.SetRelocSym(rIdx, syms.PLT)
   255  			su.SetRelocAdd(rIdx, int64(ldr.SymPlt(targ)))
   256  		}
   257  		return true
   258  
   259  	case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_PAGE21*2 + pcrel,
   260  		objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_PAGEOFF12*2:
   261  		if targType == sym.SDYNIMPORT {
   262  			ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   263  		}
   264  		su := ldr.MakeSymbolUpdater(s)
   265  		su.SetRelocType(rIdx, objabi.R_ARM64_PCREL)
   266  		return true
   267  
   268  	case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGE21*2 + pcrel,
   269  		objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12*2:
   270  		if targType != sym.SDYNIMPORT {
   271  			// have symbol
   272  			// turn MOVD sym@GOT (adrp+ldr) into MOVD $sym (adrp+add)
   273  			data := ldr.Data(s)
   274  			off := r.Off()
   275  			if int(off+3) >= len(data) {
   276  				ldr.Errorf(s, "unexpected GOT_LOAD reloc for non-dynamic symbol %s", ldr.SymName(targ))
   277  				return false
   278  			}
   279  			o := target.Arch.ByteOrder.Uint32(data[off:])
   280  			su := ldr.MakeSymbolUpdater(s)
   281  			switch {
   282  			case (o>>24)&0x9f == 0x90: // adrp
   283  				// keep instruction unchanged, change relocation type below
   284  			case o>>24 == 0xf9: // ldr
   285  				// rewrite to add
   286  				o = (0x91 << 24) | (o & (1<<22 - 1))
   287  				su.MakeWritable()
   288  				su.SetUint32(target.Arch, int64(off), o)
   289  			default:
   290  				ldr.Errorf(s, "unexpected GOT_LOAD reloc for non-dynamic symbol %s", ldr.SymName(targ))
   291  				return false
   292  			}
   293  			su.SetRelocType(rIdx, objabi.R_ARM64_PCREL)
   294  			return true
   295  		}
   296  		ld.AddGotSym(target, ldr, syms, targ, 0)
   297  		su := ldr.MakeSymbolUpdater(s)
   298  		su.SetRelocType(rIdx, objabi.R_ARM64_GOT)
   299  		su.SetRelocSym(rIdx, syms.GOT)
   300  		su.SetRelocAdd(rIdx, int64(ldr.SymGot(targ)))
   301  		return true
   302  
   303  	case objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_POINTER_TO_GOT*2 + pcrel:
   304  		if targType != sym.SDYNIMPORT {
   305  			ldr.Errorf(s, "unexpected GOT reloc for non-dynamic symbol %s", ldr.SymName(targ))
   306  		}
   307  		ld.AddGotSym(target, ldr, syms, targ, 0)
   308  		su := ldr.MakeSymbolUpdater(s)
   309  		su.SetRelocType(rIdx, objabi.R_PCREL)
   310  		su.SetRelocSym(rIdx, syms.GOT)
   311  		su.SetRelocAdd(rIdx, r.Add()+int64(r.Siz())+int64(ldr.SymGot(targ)))
   312  		return true
   313  	}
   314  
   315  	// Reread the reloc to incorporate any changes in type above.
   316  	relocs := ldr.Relocs(s)
   317  	r = relocs.At(rIdx)
   318  
   319  	switch r.Type() {
   320  	case objabi.R_CALLARM64:
   321  		if targType != sym.SDYNIMPORT {
   322  			// nothing to do, the relocation will be laid out in reloc
   323  			return true
   324  		}
   325  		if target.IsExternal() {
   326  			// External linker will do this relocation.
   327  			return true
   328  		}
   329  		// Internal linking.
   330  		if r.Add() != 0 {
   331  			ldr.Errorf(s, "PLT call with non-zero addend (%v)", r.Add())
   332  		}
   333  		// Build a PLT entry and change the relocation target to that entry.
   334  		addpltsym(target, ldr, syms, targ)
   335  		su := ldr.MakeSymbolUpdater(s)
   336  		su.SetRelocSym(rIdx, syms.PLT)
   337  		su.SetRelocAdd(rIdx, int64(ldr.SymPlt(targ)))
   338  		return true
   339  
   340  	case objabi.R_ADDRARM64:
   341  		if targType == sym.SDYNIMPORT && ldr.SymType(s).IsText() && target.IsDarwin() {
   342  			// Loading the address of a dynamic symbol. Rewrite to use GOT.
   343  			// turn MOVD $sym (adrp+add) into MOVD sym@GOT (adrp+ldr)
   344  			if r.Add() != 0 {
   345  				ldr.Errorf(s, "unexpected nonzero addend for dynamic symbol %s", ldr.SymName(targ))
   346  				return false
   347  			}
   348  			su := ldr.MakeSymbolUpdater(s)
   349  			data := ldr.Data(s)
   350  			off := r.Off()
   351  			if int(off+8) > len(data) {
   352  				ldr.Errorf(s, "unexpected R_ADDRARM64 reloc for dynamic symbol %s", ldr.SymName(targ))
   353  				return false
   354  			}
   355  			o := target.Arch.ByteOrder.Uint32(data[off+4:])
   356  			if o>>24 == 0x91 { // add
   357  				// rewrite to ldr
   358  				o = (0xf9 << 24) | 1<<22 | (o & (1<<22 - 1))
   359  				su.MakeWritable()
   360  				su.SetUint32(target.Arch, int64(off+4), o)
   361  				if target.IsInternal() {
   362  					ld.AddGotSym(target, ldr, syms, targ, 0)
   363  					su.SetRelocSym(rIdx, syms.GOT)
   364  					su.SetRelocAdd(rIdx, int64(ldr.SymGot(targ)))
   365  					su.SetRelocType(rIdx, objabi.R_ARM64_PCREL_LDST64)
   366  				} else {
   367  					su.SetRelocType(rIdx, objabi.R_ARM64_GOTPCREL)
   368  				}
   369  				return true
   370  			}
   371  			ldr.Errorf(s, "unexpected R_ADDRARM64 reloc for dynamic symbol %s", ldr.SymName(targ))
   372  		}
   373  
   374  	case objabi.R_ADDR:
   375  		if ldr.SymType(s).IsText() && target.IsElf() {
   376  			// The code is asking for the address of an external
   377  			// function. We provide it with the address of the
   378  			// correspondent GOT symbol.
   379  			ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_AARCH64_GLOB_DAT))
   380  			su := ldr.MakeSymbolUpdater(s)
   381  			su.SetRelocSym(rIdx, syms.GOT)
   382  			su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ)))
   383  			return true
   384  		}
   385  
   386  		// Process dynamic relocations for the data sections.
   387  		if target.IsPIE() && target.IsInternal() {
   388  			// When internally linking, generate dynamic relocations
   389  			// for all typical R_ADDR relocations. The exception
   390  			// are those R_ADDR that are created as part of generating
   391  			// the dynamic relocations and must be resolved statically.
   392  			//
   393  			// There are three phases relevant to understanding this:
   394  			//
   395  			//	dodata()  // we are here
   396  			//	address() // symbol address assignment
   397  			//	reloc()   // resolution of static R_ADDR relocs
   398  			//
   399  			// At this point symbol addresses have not been
   400  			// assigned yet (as the final size of the .rela section
   401  			// will affect the addresses), and so we cannot write
   402  			// the Elf64_Rela.r_offset now. Instead we delay it
   403  			// until after the 'address' phase of the linker is
   404  			// complete. We do this via Addaddrplus, which creates
   405  			// a new R_ADDR relocation which will be resolved in
   406  			// the 'reloc' phase.
   407  			//
   408  			// These synthetic static R_ADDR relocs must be skipped
   409  			// now, or else we will be caught in an infinite loop
   410  			// of generating synthetic relocs for our synthetic
   411  			// relocs.
   412  			//
   413  			// Furthermore, the rela sections contain dynamic
   414  			// relocations with R_ADDR relocations on
   415  			// Elf64_Rela.r_offset. This field should contain the
   416  			// symbol offset as determined by reloc(), not the
   417  			// final dynamically linked address as a dynamic
   418  			// relocation would provide.
   419  			switch ldr.SymName(s) {
   420  			case ".dynsym", ".rela", ".rela.plt", ".got.plt", ".dynamic":
   421  				return false
   422  			}
   423  		} else {
   424  			// Either internally linking a static executable,
   425  			// in which case we can resolve these relocations
   426  			// statically in the 'reloc' phase, or externally
   427  			// linking, in which case the relocation will be
   428  			// prepared in the 'reloc' phase and passed to the
   429  			// external linker in the 'asmb' phase.
   430  			if t := ldr.SymType(s); !t.IsDATA() && !t.IsRODATA() {
   431  				break
   432  			}
   433  		}
   434  
   435  		if target.IsElf() {
   436  			// Generate R_AARCH64_RELATIVE relocations for best
   437  			// efficiency in the dynamic linker.
   438  			//
   439  			// As noted above, symbol addresses have not been
   440  			// assigned yet, so we can't generate the final reloc
   441  			// entry yet. We ultimately want:
   442  			//
   443  			// r_offset = s + r.Off
   444  			// r_info = R_AARCH64_RELATIVE
   445  			// r_addend = targ + r.Add
   446  			//
   447  			// The dynamic linker will set *offset = base address +
   448  			// addend.
   449  			//
   450  			// AddAddrPlus is used for r_offset and r_addend to
   451  			// generate new R_ADDR relocations that will update
   452  			// these fields in the 'reloc' phase.
   453  			rela := ldr.MakeSymbolUpdater(syms.Rela)
   454  			rela.AddAddrPlus(target.Arch, s, int64(r.Off()))
   455  			if r.Siz() == 8 {
   456  				rela.AddUint64(target.Arch, elf.R_INFO(0, uint32(elf.R_AARCH64_RELATIVE)))
   457  			} else {
   458  				ldr.Errorf(s, "unexpected relocation for dynamic symbol %s", ldr.SymName(targ))
   459  			}
   460  			rela.AddAddrPlus(target.Arch, targ, r.Add())
   461  			// Not mark r done here. So we still apply it statically,
   462  			// so in the file content we'll also have the right offset
   463  			// to the relocation target. So it can be examined statically
   464  			// (e.g. go version).
   465  			return true
   466  		}
   467  
   468  		if target.IsDarwin() {
   469  			// Mach-O relocations are a royal pain to lay out.
   470  			// They use a compact stateful bytecode representation.
   471  			// Here we record what are needed and encode them later.
   472  			ld.MachoAddRebase(s, int64(r.Off()))
   473  			// Not mark r done here. So we still apply it statically,
   474  			// so in the file content we'll also have the right offset
   475  			// to the relocation target. So it can be examined statically
   476  			// (e.g. go version).
   477  			return true
   478  		}
   479  
   480  	case objabi.R_ARM64_GOTPCREL:
   481  		if target.IsExternal() {
   482  			// External linker will do this relocation.
   483  			return true
   484  		}
   485  		if targType != sym.SDYNIMPORT {
   486  			ldr.Errorf(s, "R_ARM64_GOTPCREL target is not SDYNIMPORT symbol: %v", ldr.SymName(targ))
   487  		}
   488  		if r.Add() != 0 {
   489  			ldr.Errorf(s, "R_ARM64_GOTPCREL with non-zero addend (%v)", r.Add())
   490  		}
   491  		if target.IsElf() {
   492  			ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_AARCH64_GLOB_DAT))
   493  		} else {
   494  			ld.AddGotSym(target, ldr, syms, targ, 0)
   495  		}
   496  		// turn into two relocations, one for each instruction.
   497  		su := ldr.MakeSymbolUpdater(s)
   498  		r.SetType(objabi.R_ARM64_GOT)
   499  		r.SetSiz(4)
   500  		r.SetSym(syms.GOT)
   501  		r.SetAdd(int64(ldr.SymGot(targ)))
   502  		r2, _ := su.AddRel(objabi.R_ARM64_GOT)
   503  		r2.SetSiz(4)
   504  		r2.SetOff(r.Off() + 4)
   505  		r2.SetSym(syms.GOT)
   506  		r2.SetAdd(int64(ldr.SymGot(targ)))
   507  		return true
   508  	}
   509  	return false
   510  }
   511  
   512  func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, ri int, sectoff int64) bool {
   513  	out.Write64(uint64(sectoff))
   514  
   515  	elfsym := ld.ElfSymForReloc(ctxt, r.Xsym)
   516  	siz := r.Size
   517  	switch r.Type {
   518  	default:
   519  		return false
   520  	case objabi.R_ADDR, objabi.R_DWARFSECREF:
   521  		switch siz {
   522  		case 4:
   523  			out.Write64(uint64(elf.R_AARCH64_ABS32) | uint64(elfsym)<<32)
   524  		case 8:
   525  			out.Write64(uint64(elf.R_AARCH64_ABS64) | uint64(elfsym)<<32)
   526  		default:
   527  			return false
   528  		}
   529  	case objabi.R_ADDRARM64:
   530  		// two relocations: R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_ADD_ABS_LO12_NC
   531  		out.Write64(uint64(elf.R_AARCH64_ADR_PREL_PG_HI21) | uint64(elfsym)<<32)
   532  		out.Write64(uint64(r.Xadd))
   533  		out.Write64(uint64(sectoff + 4))
   534  		out.Write64(uint64(elf.R_AARCH64_ADD_ABS_LO12_NC) | uint64(elfsym)<<32)
   535  
   536  	case objabi.R_ARM64_PCREL_LDST8,
   537  		objabi.R_ARM64_PCREL_LDST16,
   538  		objabi.R_ARM64_PCREL_LDST32,
   539  		objabi.R_ARM64_PCREL_LDST64:
   540  		// two relocations: R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_LDST{64/32/16/8}_ABS_LO12_NC
   541  		out.Write64(uint64(elf.R_AARCH64_ADR_PREL_PG_HI21) | uint64(elfsym)<<32)
   542  		out.Write64(uint64(r.Xadd))
   543  		out.Write64(uint64(sectoff + 4))
   544  		var ldstType elf.R_AARCH64
   545  		switch r.Type {
   546  		case objabi.R_ARM64_PCREL_LDST8:
   547  			ldstType = elf.R_AARCH64_LDST8_ABS_LO12_NC
   548  		case objabi.R_ARM64_PCREL_LDST16:
   549  			ldstType = elf.R_AARCH64_LDST16_ABS_LO12_NC
   550  		case objabi.R_ARM64_PCREL_LDST32:
   551  			ldstType = elf.R_AARCH64_LDST32_ABS_LO12_NC
   552  		case objabi.R_ARM64_PCREL_LDST64:
   553  			ldstType = elf.R_AARCH64_LDST64_ABS_LO12_NC
   554  		}
   555  		out.Write64(uint64(ldstType) | uint64(elfsym)<<32)
   556  
   557  	case objabi.R_ARM64_TLS_LE:
   558  		out.Write64(uint64(elf.R_AARCH64_TLSLE_MOVW_TPREL_G0) | uint64(elfsym)<<32)
   559  	case objabi.R_ARM64_TLS_IE:
   560  		out.Write64(uint64(elf.R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21) | uint64(elfsym)<<32)
   561  		out.Write64(uint64(r.Xadd))
   562  		out.Write64(uint64(sectoff + 4))
   563  		out.Write64(uint64(elf.R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC) | uint64(elfsym)<<32)
   564  	case objabi.R_ARM64_GOTPCREL:
   565  		out.Write64(uint64(elf.R_AARCH64_ADR_GOT_PAGE) | uint64(elfsym)<<32)
   566  		out.Write64(uint64(r.Xadd))
   567  		out.Write64(uint64(sectoff + 4))
   568  		out.Write64(uint64(elf.R_AARCH64_LD64_GOT_LO12_NC) | uint64(elfsym)<<32)
   569  	case objabi.R_CALLARM64:
   570  		if siz != 4 {
   571  			return false
   572  		}
   573  		out.Write64(uint64(elf.R_AARCH64_CALL26) | uint64(elfsym)<<32)
   574  
   575  	}
   576  	out.Write64(uint64(r.Xadd))
   577  
   578  	return true
   579  }
   580  
   581  // sign-extends from 21, 24-bit.
   582  func signext21(x int64) int64 { return x << (64 - 21) >> (64 - 21) }
   583  func signext24(x int64) int64 { return x << (64 - 24) >> (64 - 24) }
   584  
   585  func machoreloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
   586  	var v uint32
   587  
   588  	rs := r.Xsym
   589  	rt := r.Type
   590  	siz := r.Size
   591  	xadd := r.Xadd
   592  
   593  	if xadd != signext24(xadd) && rt != objabi.R_ADDR {
   594  		// If the relocation target would overflow the addend, then target
   595  		// a linker-manufactured label symbol with a smaller addend instead.
   596  		// R_ADDR has full-width addend encoded in data content, so it doesn't
   597  		// use a label symbol.
   598  		label := ldr.Lookup(offsetLabelName(ldr, rs, xadd/machoRelocLimit*machoRelocLimit), ldr.SymVersion(rs))
   599  		if label != 0 {
   600  			xadd = ldr.SymValue(rs) + xadd - ldr.SymValue(label)
   601  			rs = label
   602  		}
   603  		if xadd != signext24(xadd) {
   604  			ldr.Errorf(s, "internal error: relocation addend overflow: %s+0x%x", ldr.SymName(rs), xadd)
   605  		}
   606  	}
   607  	if rt == objabi.R_CALLARM64 && xadd != 0 {
   608  		label := ldr.Lookup(offsetLabelName(ldr, rs, xadd), ldr.SymVersion(rs))
   609  		if label != 0 {
   610  			xadd = ldr.SymValue(rs) + xadd - ldr.SymValue(label) // should always be 0 (checked below)
   611  			rs = label
   612  		}
   613  	}
   614  
   615  	if !ldr.SymType(s).IsDWARF() {
   616  		if ldr.SymDynid(rs) < 0 {
   617  			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))
   618  			return false
   619  		}
   620  
   621  		v = uint32(ldr.SymDynid(rs))
   622  		v |= 1 << 27 // external relocation
   623  	} else {
   624  		v = uint32(ldr.SymSect(rs).Extnum)
   625  		if v == 0 {
   626  			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))
   627  			return false
   628  		}
   629  	}
   630  
   631  	switch rt {
   632  	default:
   633  		return false
   634  	case objabi.R_ADDR:
   635  		v |= ld.MACHO_ARM64_RELOC_UNSIGNED << 28
   636  	case objabi.R_CALLARM64:
   637  		if xadd != 0 {
   638  			// Addend should be handled above via label symbols.
   639  			ldr.Errorf(s, "unexpected non-zero addend: %s+%d", ldr.SymName(rs), xadd)
   640  		}
   641  		v |= 1 << 24 // pc-relative bit
   642  		v |= ld.MACHO_ARM64_RELOC_BRANCH26 << 28
   643  	case objabi.R_ADDRARM64,
   644  		objabi.R_ARM64_PCREL_LDST8,
   645  		objabi.R_ARM64_PCREL_LDST16,
   646  		objabi.R_ARM64_PCREL_LDST32,
   647  		objabi.R_ARM64_PCREL_LDST64:
   648  		siz = 4
   649  		// Two relocation entries: MACHO_ARM64_RELOC_PAGEOFF12 MACHO_ARM64_RELOC_PAGE21
   650  		// if r.Xadd is non-zero, add two MACHO_ARM64_RELOC_ADDEND.
   651  		if r.Xadd != 0 {
   652  			out.Write32(uint32(sectoff + 4))
   653  			out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
   654  		}
   655  		out.Write32(uint32(sectoff + 4))
   656  		out.Write32(v | (ld.MACHO_ARM64_RELOC_PAGEOFF12 << 28) | (2 << 25))
   657  		if r.Xadd != 0 {
   658  			out.Write32(uint32(sectoff))
   659  			out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
   660  		}
   661  		v |= 1 << 24 // pc-relative bit
   662  		v |= ld.MACHO_ARM64_RELOC_PAGE21 << 28
   663  	case objabi.R_ARM64_GOTPCREL:
   664  		siz = 4
   665  		// Two relocation entries: MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12 MACHO_ARM64_RELOC_GOT_LOAD_PAGE21
   666  		// if r.Xadd is non-zero, add two MACHO_ARM64_RELOC_ADDEND.
   667  		if r.Xadd != 0 {
   668  			out.Write32(uint32(sectoff + 4))
   669  			out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
   670  		}
   671  		out.Write32(uint32(sectoff + 4))
   672  		out.Write32(v | (ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGEOFF12 << 28) | (2 << 25))
   673  		if r.Xadd != 0 {
   674  			out.Write32(uint32(sectoff))
   675  			out.Write32((ld.MACHO_ARM64_RELOC_ADDEND << 28) | (2 << 25) | uint32(xadd&0xffffff))
   676  		}
   677  		v |= 1 << 24 // pc-relative bit
   678  		v |= ld.MACHO_ARM64_RELOC_GOT_LOAD_PAGE21 << 28
   679  	}
   680  
   681  	switch siz {
   682  	default:
   683  		return false
   684  	case 1:
   685  		v |= 0 << 25
   686  	case 2:
   687  		v |= 1 << 25
   688  	case 4:
   689  		v |= 2 << 25
   690  	case 8:
   691  		v |= 3 << 25
   692  	}
   693  
   694  	out.Write32(uint32(sectoff))
   695  	out.Write32(v)
   696  	return true
   697  }
   698  
   699  func pereloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
   700  	rs := r.Xsym
   701  	rt := r.Type
   702  
   703  	if (rt == objabi.R_ADDRARM64 || rt == objabi.R_ARM64_PCREL_LDST8 || rt == objabi.R_ARM64_PCREL_LDST16 ||
   704  		rt == objabi.R_ARM64_PCREL_LDST32 || rt == objabi.R_ARM64_PCREL_LDST64) && r.Xadd != signext21(r.Xadd) {
   705  		// If the relocation target would overflow the addend, then target
   706  		// a linker-manufactured label symbol with a smaller addend instead.
   707  		label := ldr.Lookup(offsetLabelName(ldr, rs, r.Xadd/peRelocLimit*peRelocLimit), ldr.SymVersion(rs))
   708  		if label == 0 {
   709  			ldr.Errorf(s, "invalid relocation: %v %s+0x%x", rt, ldr.SymName(rs), r.Xadd)
   710  			return false
   711  		}
   712  		rs = label
   713  	}
   714  	if rt == objabi.R_CALLARM64 && r.Xadd != 0 {
   715  		label := ldr.Lookup(offsetLabelName(ldr, rs, r.Xadd), ldr.SymVersion(rs))
   716  		if label == 0 {
   717  			ldr.Errorf(s, "invalid relocation: %v %s+0x%x", rt, ldr.SymName(rs), r.Xadd)
   718  			return false
   719  		}
   720  		rs = label
   721  	}
   722  	symdynid := ldr.SymDynid(rs)
   723  	if symdynid < 0 {
   724  		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))
   725  		return false
   726  	}
   727  
   728  	switch rt {
   729  	default:
   730  		return false
   731  
   732  	case objabi.R_DWARFSECREF:
   733  		out.Write32(uint32(sectoff))
   734  		out.Write32(uint32(symdynid))
   735  		out.Write16(ld.IMAGE_REL_ARM64_SECREL)
   736  
   737  	case objabi.R_ADDR:
   738  		out.Write32(uint32(sectoff))
   739  		out.Write32(uint32(symdynid))
   740  		if r.Size == 8 {
   741  			out.Write16(ld.IMAGE_REL_ARM64_ADDR64)
   742  		} else {
   743  			out.Write16(ld.IMAGE_REL_ARM64_ADDR32)
   744  		}
   745  
   746  	case objabi.R_PEIMAGEOFF:
   747  		out.Write16(ld.IMAGE_REL_ARM64_ADDR32NB)
   748  
   749  	case objabi.R_ADDRARM64:
   750  		// Note: r.Xadd has been taken care of below, in archreloc.
   751  		out.Write32(uint32(sectoff))
   752  		out.Write32(uint32(symdynid))
   753  		out.Write16(ld.IMAGE_REL_ARM64_PAGEBASE_REL21)
   754  
   755  		out.Write32(uint32(sectoff + 4))
   756  		out.Write32(uint32(symdynid))
   757  		out.Write16(ld.IMAGE_REL_ARM64_PAGEOFFSET_12A)
   758  
   759  	case objabi.R_ARM64_PCREL_LDST8,
   760  		objabi.R_ARM64_PCREL_LDST16,
   761  		objabi.R_ARM64_PCREL_LDST32,
   762  		objabi.R_ARM64_PCREL_LDST64:
   763  		// Note: r.Xadd has been taken care of below, in archreloc.
   764  		out.Write32(uint32(sectoff))
   765  		out.Write32(uint32(symdynid))
   766  		out.Write16(ld.IMAGE_REL_ARM64_PAGEBASE_REL21)
   767  
   768  		out.Write32(uint32(sectoff + 4))
   769  		out.Write32(uint32(symdynid))
   770  		out.Write16(ld.IMAGE_REL_ARM64_PAGEOFFSET_12L)
   771  
   772  	case objabi.R_CALLARM64:
   773  		// Note: r.Xadd has been taken care of above, by using a label pointing into the middle of the function.
   774  		out.Write32(uint32(sectoff))
   775  		out.Write32(uint32(symdynid))
   776  		out.Write16(ld.IMAGE_REL_ARM64_BRANCH26)
   777  	}
   778  
   779  	return true
   780  }
   781  
   782  func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loader.Reloc, s loader.Sym, val int64) (int64, int, bool) {
   783  	const noExtReloc = 0
   784  	const isOk = true
   785  
   786  	rs := r.Sym()
   787  
   788  	if target.IsExternal() {
   789  		nExtReloc := 0
   790  		switch rt := r.Type(); rt {
   791  		default:
   792  		case objabi.R_ARM64_GOTPCREL,
   793  			objabi.R_ARM64_PCREL_LDST8,
   794  			objabi.R_ARM64_PCREL_LDST16,
   795  			objabi.R_ARM64_PCREL_LDST32,
   796  			objabi.R_ARM64_PCREL_LDST64,
   797  			objabi.R_ADDRARM64:
   798  
   799  			// set up addend for eventual relocation via outer symbol.
   800  			rs, off := ld.FoldSubSymbolOffset(ldr, rs)
   801  			xadd := r.Add() + off
   802  			rst := ldr.SymType(rs)
   803  			if rst != sym.SHOSTOBJ && rst != sym.SDYNIMPORT && ldr.SymSect(rs) == nil {
   804  				ldr.Errorf(s, "missing section for %s", ldr.SymName(rs))
   805  			}
   806  
   807  			nExtReloc = 2 // need two ELF/Mach-O relocations. see elfreloc1/machoreloc1
   808  			if target.IsDarwin() && xadd != 0 {
   809  				nExtReloc = 4 // need another two relocations for non-zero addend
   810  			}
   811  
   812  			if target.IsWindows() {
   813  				var o0, o1 uint32
   814  				if target.IsBigEndian() {
   815  					o0 = uint32(val >> 32)
   816  					o1 = uint32(val)
   817  				} else {
   818  					o0 = uint32(val)
   819  					o1 = uint32(val >> 32)
   820  				}
   821  
   822  				// The first instruction (ADRP) has a 21-bit immediate field,
   823  				// and the second (ADD or LD/ST) has a 12-bit immediate field.
   824  				// The first instruction is only for high bits, but to get the carry bits right we have
   825  				// to put the full addend, including the bottom 12 bits again.
   826  				// That limits the distance of any addend to only 21 bits.
   827  				// But we assume that ADRP's top bit will be interpreted as a sign bit,
   828  				// so we only use 20 bits.
   829  				// pereloc takes care of introducing new symbol labels
   830  				// every megabyte for longer relocations.
   831  				xadd := uint32(xadd)
   832  				o0 |= (xadd&3)<<29 | (xadd&0xffffc)<<3
   833  				switch rt {
   834  				case objabi.R_ARM64_PCREL_LDST8, objabi.R_ADDRARM64:
   835  					o1 |= (xadd & 0xfff) << 10
   836  				case objabi.R_ARM64_PCREL_LDST16:
   837  					if xadd&0x1 != 0 {
   838  						ldr.Errorf(s, "offset for 16-bit load/store has unaligned value %d", xadd&0xfff)
   839  					}
   840  					o1 |= ((xadd & 0xfff) >> 1) << 10
   841  				case objabi.R_ARM64_PCREL_LDST32:
   842  					if xadd&0x3 != 0 {
   843  						ldr.Errorf(s, "offset for 32-bit load/store has unaligned value %d", xadd&0xfff)
   844  					}
   845  					o1 |= ((xadd & 0xfff) >> 2) << 10
   846  				case objabi.R_ARM64_PCREL_LDST64:
   847  					if xadd&0x7 != 0 {
   848  						ldr.Errorf(s, "offset for 64-bit load/store has unaligned value %d", xadd&0xfff)
   849  					}
   850  					o1 |= ((xadd & 0xfff) >> 3) << 10
   851  				}
   852  
   853  				if target.IsBigEndian() {
   854  					val = int64(o0)<<32 | int64(o1)
   855  				} else {
   856  					val = int64(o1)<<32 | int64(o0)
   857  				}
   858  			}
   859  
   860  			return val, nExtReloc, isOk
   861  
   862  		case objabi.R_CALLARM64:
   863  			nExtReloc = 1
   864  			return val, nExtReloc, isOk
   865  
   866  		case objabi.R_ARM64_TLS_LE:
   867  			nExtReloc = 1
   868  			return val, nExtReloc, isOk
   869  
   870  		case objabi.R_ARM64_TLS_IE:
   871  			nExtReloc = 2 // need two ELF relocations. see elfreloc1
   872  			return val, nExtReloc, isOk
   873  
   874  		case objabi.R_ADDR:
   875  			if target.IsWindows() && r.Add() != 0 {
   876  				if r.Siz() == 8 {
   877  					val = r.Add()
   878  				} else if target.IsBigEndian() {
   879  					val = int64(uint32(val)) | r.Add()<<32
   880  				} else {
   881  					val = val>>32<<32 | int64(uint32(r.Add()))
   882  				}
   883  				return val, 1, true
   884  			}
   885  		}
   886  	}
   887  
   888  	switch rt := r.Type(); rt {
   889  	case objabi.R_ADDRARM64,
   890  		objabi.R_ARM64_PCREL_LDST8,
   891  		objabi.R_ARM64_PCREL_LDST16,
   892  		objabi.R_ARM64_PCREL_LDST32,
   893  		objabi.R_ARM64_PCREL_LDST64:
   894  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
   895  		if t >= 1<<32 || t < -1<<32 {
   896  			ldr.Errorf(s, "program too large, address relocation distance = %d", t)
   897  		}
   898  
   899  		var o0, o1 uint32
   900  
   901  		if target.IsBigEndian() {
   902  			o0 = uint32(val >> 32)
   903  			o1 = uint32(val)
   904  		} else {
   905  			o0 = uint32(val)
   906  			o1 = uint32(val >> 32)
   907  		}
   908  
   909  		o0 |= (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
   910  		switch rt {
   911  		case objabi.R_ARM64_PCREL_LDST8, objabi.R_ADDRARM64:
   912  			o1 |= uint32(t&0xfff) << 10
   913  		case objabi.R_ARM64_PCREL_LDST16:
   914  			if t&0x1 != 0 {
   915  				ldr.Errorf(s, "offset for 16-bit load/store has unaligned value %d", t&0xfff)
   916  			}
   917  			o1 |= (uint32(t&0xfff) >> 1) << 10
   918  		case objabi.R_ARM64_PCREL_LDST32:
   919  			if t&0x3 != 0 {
   920  				ldr.Errorf(s, "offset for 32-bit load/store has unaligned value %d", t&0xfff)
   921  			}
   922  			o1 |= (uint32(t&0xfff) >> 2) << 10
   923  		case objabi.R_ARM64_PCREL_LDST64:
   924  			if t&0x7 != 0 {
   925  				ldr.Errorf(s, "offset for 64-bit load/store has unaligned value %d", t&0xfff)
   926  			}
   927  			o1 |= (uint32(t&0xfff) >> 3) << 10
   928  		}
   929  
   930  		// when laid out, the instruction order must always be o1, o2.
   931  		if target.IsBigEndian() {
   932  			return int64(o0)<<32 | int64(o1), noExtReloc, true
   933  		}
   934  		return int64(o1)<<32 | int64(o0), noExtReloc, true
   935  
   936  	case objabi.R_ARM64_TLS_LE:
   937  		if target.IsDarwin() {
   938  			ldr.Errorf(s, "TLS reloc on unsupported OS %v", target.HeadType)
   939  		}
   940  		// The TCB is two pointers. This is not documented anywhere, but is
   941  		// de facto part of the ABI.
   942  		v := ldr.SymValue(rs) + int64(2*target.Arch.PtrSize)
   943  		if v < 0 || v >= 32678 {
   944  			ldr.Errorf(s, "TLS offset out of range %d", v)
   945  		}
   946  		return val | (v << 5), noExtReloc, true
   947  
   948  	case objabi.R_ARM64_TLS_IE:
   949  		if target.IsPIE() && target.IsElf() {
   950  			// We are linking the final executable, so we
   951  			// can optimize any TLS IE relocation to LE.
   952  
   953  			if !target.IsLinux() {
   954  				ldr.Errorf(s, "TLS reloc on unsupported OS %v", target.HeadType)
   955  			}
   956  
   957  			// The TCB is two pointers. This is not documented anywhere, but is
   958  			// de facto part of the ABI.
   959  			v := ldr.SymAddr(rs) + int64(2*target.Arch.PtrSize) + r.Add()
   960  			if v < 0 || v >= 32678 {
   961  				ldr.Errorf(s, "TLS offset out of range %d", v)
   962  			}
   963  
   964  			var o0, o1 uint32
   965  			if target.IsBigEndian() {
   966  				o0 = uint32(val >> 32)
   967  				o1 = uint32(val)
   968  			} else {
   969  				o0 = uint32(val)
   970  				o1 = uint32(val >> 32)
   971  			}
   972  
   973  			// R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21
   974  			// turn ADRP to MOVZ
   975  			o0 = 0xd2a00000 | o0&0x1f | (uint32((v>>16)&0xffff) << 5)
   976  			// R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC
   977  			// turn LD64 to MOVK
   978  			if v&3 != 0 {
   979  				ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC", v)
   980  			}
   981  			o1 = 0xf2800000 | o1&0x1f | (uint32(v&0xffff) << 5)
   982  
   983  			// when laid out, the instruction order must always be o0, o1.
   984  			if target.IsBigEndian() {
   985  				return int64(o0)<<32 | int64(o1), noExtReloc, isOk
   986  			}
   987  			return int64(o1)<<32 | int64(o0), noExtReloc, isOk
   988  		} else {
   989  			log.Fatalf("cannot handle R_ARM64_TLS_IE (sym %s) when linking internally", ldr.SymName(s))
   990  		}
   991  
   992  	case objabi.R_CALLARM64:
   993  		var t int64
   994  		if ldr.SymType(rs) == sym.SDYNIMPORT {
   995  			t = (ldr.SymAddr(syms.PLT) + r.Add()) - (ldr.SymValue(s) + int64(r.Off()))
   996  		} else {
   997  			t = (ldr.SymAddr(rs) + r.Add()) - (ldr.SymValue(s) + int64(r.Off()))
   998  		}
   999  		if t >= 1<<27 || t < -1<<27 {
  1000  			ldr.Errorf(s, "program too large, call relocation distance = %d", t)
  1001  		}
  1002  		return val | ((t >> 2) & 0x03ffffff), noExtReloc, true
  1003  
  1004  	case objabi.R_ARM64_GOT:
  1005  		if (val>>24)&0x9f == 0x90 {
  1006  			// R_AARCH64_ADR_GOT_PAGE
  1007  			// patch instruction: adrp
  1008  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1009  			if t >= 1<<32 || t < -1<<32 {
  1010  				ldr.Errorf(s, "program too large, address relocation distance = %d", t)
  1011  			}
  1012  			var o0 uint32
  1013  			o0 |= (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
  1014  			return val | int64(o0), noExtReloc, isOk
  1015  		} else if val>>24 == 0xf9 {
  1016  			// R_AARCH64_LD64_GOT_LO12_NC
  1017  			// patch instruction: ldr
  1018  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1019  			if t&7 != 0 {
  1020  				ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LD64_GOT_LO12_NC", t)
  1021  			}
  1022  			var o1 uint32
  1023  			o1 |= uint32(t&0xfff) << (10 - 3)
  1024  			return val | int64(uint64(o1)), noExtReloc, isOk
  1025  		} else {
  1026  			ldr.Errorf(s, "unsupported instruction for %x R_GOTARM64", val)
  1027  		}
  1028  
  1029  	case objabi.R_ARM64_PCREL:
  1030  		// When targetting Windows, the instruction immediate field is cleared
  1031  		// before applying relocations, as it contains the offset as bytes
  1032  		// instead of pages. It has already been accounted for in loadpe.Load
  1033  		// by adjusting r.Add().
  1034  		if (val>>24)&0x9f == 0x90 {
  1035  			// ELF R_AARCH64_ADR_PREL_PG_HI21, or Mach-O ARM64_RELOC_PAGE21, or PE IMAGE_REL_ARM64_PAGEBASE_REL21
  1036  			// patch instruction: adrp
  1037  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1038  			if t >= 1<<32 || t < -1<<32 {
  1039  				ldr.Errorf(s, "program too large, address relocation distance = %d", t)
  1040  			}
  1041  			o0 := (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
  1042  			if target.IsWindows() {
  1043  				val &^= 3<<29 | 0x7ffff<<5
  1044  			}
  1045  			return val | int64(o0), noExtReloc, isOk
  1046  		} else if (val>>24)&0x9f == 0x91 {
  1047  			// ELF R_AARCH64_ADD_ABS_LO12_NC, or Mach-O ARM64_RELOC_PAGEOFF12, or PE IMAGE_REL_ARM64_PAGEOFFSET_12A
  1048  			// patch instruction: add
  1049  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1050  			o1 := uint32(t&0xfff) << 10
  1051  			if target.IsWindows() {
  1052  				val &^= 0xfff << 10
  1053  			}
  1054  			return val | int64(o1), noExtReloc, isOk
  1055  		} else if (val>>24)&0x3b == 0x39 {
  1056  			// Mach-O ARM64_RELOC_PAGEOFF12 or PE IMAGE_REL_ARM64_PAGEOFFSET_12L
  1057  			// patch ldr/str(b/h/w/d/q) (integer or vector) instructions, which have different scaling factors.
  1058  			// Mach-O and PE use same relocation type for them.
  1059  			shift := uint32(val) >> 30
  1060  			if shift == 0 && (val>>20)&0x048 == 0x048 { // 128-bit vector load
  1061  				shift = 4
  1062  			}
  1063  			t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1064  			if t&(1<<shift-1) != 0 {
  1065  				ldr.Errorf(s, "invalid address: %x for relocation type: ARM64_RELOC_PAGEOFF12", t)
  1066  			}
  1067  			o1 := (uint32(t&0xfff) >> shift) << 10
  1068  			if target.IsWindows() {
  1069  				val &^= 0xfff << 10
  1070  			}
  1071  			return val | int64(o1), noExtReloc, isOk
  1072  		} else {
  1073  			ldr.Errorf(s, "unsupported instruction for %x R_ARM64_PCREL", val)
  1074  		}
  1075  
  1076  	case objabi.R_ARM64_LDST8:
  1077  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1078  		o0 := uint32(t&0xfff) << 10
  1079  		return val | int64(o0), noExtReloc, true
  1080  
  1081  	case objabi.R_ARM64_LDST16:
  1082  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1083  		if t&1 != 0 {
  1084  			ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST16_ABS_LO12_NC", t)
  1085  		}
  1086  		o0 := (uint32(t&0xfff) >> 1) << 10
  1087  		return val | int64(o0), noExtReloc, true
  1088  
  1089  	case objabi.R_ARM64_LDST32:
  1090  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1091  		if t&3 != 0 {
  1092  			ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST32_ABS_LO12_NC", t)
  1093  		}
  1094  		o0 := (uint32(t&0xfff) >> 2) << 10
  1095  		return val | int64(o0), noExtReloc, true
  1096  
  1097  	case objabi.R_ARM64_LDST64:
  1098  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1099  		if t&7 != 0 {
  1100  			ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST64_ABS_LO12_NC", t)
  1101  		}
  1102  		o0 := (uint32(t&0xfff) >> 3) << 10
  1103  		return val | int64(o0), noExtReloc, true
  1104  
  1105  	case objabi.R_ARM64_LDST128:
  1106  		t := ldr.SymAddr(rs) + r.Add() - ((ldr.SymValue(s) + int64(r.Off())) &^ 0xfff)
  1107  		if t&15 != 0 {
  1108  			ldr.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST128_ABS_LO12_NC", t)
  1109  		}
  1110  		o0 := (uint32(t&0xfff) >> 4) << 10
  1111  		return val | int64(o0), noExtReloc, true
  1112  	}
  1113  
  1114  	return val, 0, false
  1115  }
  1116  
  1117  func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
  1118  	log.Fatalf("unexpected relocation variant")
  1119  	return -1
  1120  }
  1121  
  1122  func extreloc(target *ld.Target, ldr *loader.Loader, r loader.Reloc, s loader.Sym) (loader.ExtReloc, bool) {
  1123  	switch rt := r.Type(); rt {
  1124  	case objabi.R_ARM64_GOTPCREL,
  1125  		objabi.R_ARM64_PCREL_LDST8,
  1126  		objabi.R_ARM64_PCREL_LDST16,
  1127  		objabi.R_ARM64_PCREL_LDST32,
  1128  		objabi.R_ARM64_PCREL_LDST64,
  1129  		objabi.R_ADDRARM64:
  1130  		rr := ld.ExtrelocViaOuterSym(ldr, r, s)
  1131  		return rr, true
  1132  	case objabi.R_CALLARM64,
  1133  		objabi.R_ARM64_TLS_LE,
  1134  		objabi.R_ARM64_TLS_IE:
  1135  		return ld.ExtrelocSimple(ldr, r), true
  1136  	}
  1137  	return loader.ExtReloc{}, false
  1138  }
  1139  
  1140  func elfsetupplt(ctxt *ld.Link, ldr *loader.Loader, plt, gotplt *loader.SymbolBuilder, dynamic loader.Sym) {
  1141  	if plt.Size() == 0 {
  1142  		// stp     x16, x30, [sp, #-16]!
  1143  		// identifying information
  1144  		plt.AddUint32(ctxt.Arch, 0xa9bf7bf0)
  1145  
  1146  		// the following two instructions (adrp + ldr) load *got[2] into x17
  1147  		// adrp    x16, &got[0]
  1148  		plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_GOT, 4)
  1149  		plt.SetUint32(ctxt.Arch, plt.Size()-4, 0x90000010)
  1150  
  1151  		// <imm> is the offset value of &got[2] to &got[0], the same below
  1152  		// ldr     x17, [x16, <imm>]
  1153  		plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_GOT, 4)
  1154  		plt.SetUint32(ctxt.Arch, plt.Size()-4, 0xf9400211)
  1155  
  1156  		// add     x16, x16, <imm>
  1157  		plt.AddSymRef(ctxt.Arch, gotplt.Sym(), 16, objabi.R_ARM64_PCREL, 4)
  1158  		plt.SetUint32(ctxt.Arch, plt.Size()-4, 0x91000210)
  1159  
  1160  		// br      x17
  1161  		plt.AddUint32(ctxt.Arch, 0xd61f0220)
  1162  
  1163  		// 3 nop for place holder
  1164  		plt.AddUint32(ctxt.Arch, 0xd503201f)
  1165  		plt.AddUint32(ctxt.Arch, 0xd503201f)
  1166  		plt.AddUint32(ctxt.Arch, 0xd503201f)
  1167  
  1168  		// check gotplt.size == 0
  1169  		if gotplt.Size() != 0 {
  1170  			ctxt.Errorf(gotplt.Sym(), "got.plt is not empty at the very beginning")
  1171  		}
  1172  		gotplt.AddAddrPlus(ctxt.Arch, dynamic, 0)
  1173  
  1174  		gotplt.AddUint64(ctxt.Arch, 0)
  1175  		gotplt.AddUint64(ctxt.Arch, 0)
  1176  	}
  1177  }
  1178  
  1179  func addpltsym(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym) {
  1180  	if ldr.SymPlt(s) >= 0 {
  1181  		return
  1182  	}
  1183  
  1184  	ld.Adddynsym(ldr, target, syms, s)
  1185  
  1186  	if target.IsElf() {
  1187  		plt := ldr.MakeSymbolUpdater(syms.PLT)
  1188  		gotplt := ldr.MakeSymbolUpdater(syms.GOTPLT)
  1189  		rela := ldr.MakeSymbolUpdater(syms.RelaPLT)
  1190  		if plt.Size() == 0 {
  1191  			panic("plt is not set up")
  1192  		}
  1193  
  1194  		// adrp    x16, &got.plt[0]
  1195  		plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
  1196  		plt.SetUint32(target.Arch, plt.Size()-4, 0x90000010)
  1197  		relocs := plt.Relocs()
  1198  		plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_GOT)
  1199  
  1200  		// <offset> is the offset value of &got.plt[n] to &got.plt[0]
  1201  		// ldr     x17, [x16, <offset>]
  1202  		plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
  1203  		plt.SetUint32(target.Arch, plt.Size()-4, 0xf9400211)
  1204  		relocs = plt.Relocs()
  1205  		plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_GOT)
  1206  
  1207  		// add     x16, x16, <offset>
  1208  		plt.AddAddrPlus4(target.Arch, gotplt.Sym(), gotplt.Size())
  1209  		plt.SetUint32(target.Arch, plt.Size()-4, 0x91000210)
  1210  		relocs = plt.Relocs()
  1211  		plt.SetRelocType(relocs.Count()-1, objabi.R_ARM64_PCREL)
  1212  
  1213  		// br      x17
  1214  		plt.AddUint32(target.Arch, 0xd61f0220)
  1215  
  1216  		// add to got.plt: pointer to plt[0]
  1217  		gotplt.AddAddrPlus(target.Arch, plt.Sym(), 0)
  1218  
  1219  		// rela
  1220  		rela.AddAddrPlus(target.Arch, gotplt.Sym(), gotplt.Size()-8)
  1221  		sDynid := ldr.SymDynid(s)
  1222  
  1223  		rela.AddUint64(target.Arch, elf.R_INFO(uint32(sDynid), uint32(elf.R_AARCH64_JUMP_SLOT)))
  1224  		rela.AddUint64(target.Arch, 0)
  1225  
  1226  		ldr.SetPlt(s, int32(plt.Size()-16))
  1227  	} else if target.IsDarwin() {
  1228  		ld.AddGotSym(target, ldr, syms, s, 0)
  1229  
  1230  		sDynid := ldr.SymDynid(s)
  1231  		lep := ldr.MakeSymbolUpdater(syms.LinkEditPLT)
  1232  		lep.AddUint32(target.Arch, uint32(sDynid))
  1233  
  1234  		plt := ldr.MakeSymbolUpdater(syms.PLT)
  1235  		ldr.SetPlt(s, int32(plt.Size()))
  1236  
  1237  		// adrp x16, GOT
  1238  		plt.AddUint32(target.Arch, 0x90000010)
  1239  		r, _ := plt.AddRel(objabi.R_ARM64_GOT)
  1240  		r.SetOff(int32(plt.Size() - 4))
  1241  		r.SetSiz(4)
  1242  		r.SetSym(syms.GOT)
  1243  		r.SetAdd(int64(ldr.SymGot(s)))
  1244  
  1245  		// ldr x17, [x16, <offset>]
  1246  		plt.AddUint32(target.Arch, 0xf9400211)
  1247  		r, _ = plt.AddRel(objabi.R_ARM64_GOT)
  1248  		r.SetOff(int32(plt.Size() - 4))
  1249  		r.SetSiz(4)
  1250  		r.SetSym(syms.GOT)
  1251  		r.SetAdd(int64(ldr.SymGot(s)))
  1252  
  1253  		// br x17
  1254  		plt.AddUint32(target.Arch, 0xd61f0220)
  1255  	} else {
  1256  		ldr.Errorf(s, "addpltsym: unsupported binary format")
  1257  	}
  1258  }
  1259  
  1260  const (
  1261  	machoRelocLimit = 1 << 23
  1262  	peRelocLimit    = 1 << 20
  1263  )
  1264  
  1265  func gensymlate(ctxt *ld.Link, ldr *loader.Loader) {
  1266  	// When external linking on darwin, Mach-O relocation has only signed 24-bit
  1267  	// addend. For large symbols, we generate "label" symbols in the middle, so
  1268  	// that relocations can target them with smaller addends.
  1269  	// On Windows, we only get 21 bits, again (presumably) signed.
  1270  	// Also, on Windows (always) and Darwin (for very large binaries), the external
  1271  	// linker doesn't support CALL relocations with addend, so we generate "label"
  1272  	// symbols for functions of which we can target the middle (Duff's devices).
  1273  	if !ctxt.IsDarwin() && !ctxt.IsWindows() || !ctxt.IsExternal() {
  1274  		return
  1275  	}
  1276  
  1277  	limit := int64(machoRelocLimit)
  1278  	if ctxt.IsWindows() {
  1279  		limit = peRelocLimit
  1280  	}
  1281  
  1282  	// addLabelSyms adds "label" symbols at s+limit, s+2*limit, etc.
  1283  	addLabelSyms := func(s loader.Sym, limit, sz int64) {
  1284  		if ldr.SymSect(s) == nil {
  1285  			log.Fatalf("gensymlate: symbol %s has no section (type=%v)", ldr.SymName(s), ldr.SymType(s))
  1286  		}
  1287  		v := ldr.SymValue(s)
  1288  		for off := limit; off < sz; off += limit {
  1289  			p := ldr.LookupOrCreateSym(offsetLabelName(ldr, s, off), ldr.SymVersion(s))
  1290  			ldr.SetAttrReachable(p, true)
  1291  			ldr.SetSymValue(p, v+off)
  1292  			ldr.SetSymSect(p, ldr.SymSect(s))
  1293  			if ctxt.IsDarwin() {
  1294  				ld.AddMachoSym(ldr, p)
  1295  			} else if ctxt.IsWindows() {
  1296  				ld.AddPELabelSym(ldr, p)
  1297  			} else {
  1298  				panic("missing case in gensymlate")
  1299  			}
  1300  			// fmt.Printf("gensymlate %s %x\n", ldr.SymName(p), ldr.SymValue(p))
  1301  		}
  1302  	}
  1303  
  1304  	// Generate symbol names for every offset we need in duffcopy/duffzero (only 64 each).
  1305  	if s := ldr.Lookup("runtime.duffcopy", sym.SymVerABIInternal); s != 0 && ldr.AttrReachable(s) {
  1306  		addLabelSyms(s, 8, 8*64)
  1307  	}
  1308  	if s := ldr.Lookup("runtime.duffzero", sym.SymVerABIInternal); s != 0 && ldr.AttrReachable(s) {
  1309  		addLabelSyms(s, 4, 4*64)
  1310  	}
  1311  
  1312  	if ctxt.IsDarwin() {
  1313  		big := false
  1314  		for _, seg := range ld.Segments {
  1315  			if seg.Length >= machoRelocLimit {
  1316  				big = true
  1317  				break
  1318  			}
  1319  		}
  1320  		if !big {
  1321  			return // skip work if nothing big
  1322  		}
  1323  	}
  1324  
  1325  	for s, n := loader.Sym(1), loader.Sym(ldr.NSym()); s < n; s++ {
  1326  		if !ldr.AttrReachable(s) {
  1327  			continue
  1328  		}
  1329  		t := ldr.SymType(s)
  1330  		if t.IsText() {
  1331  			// Except for Duff's devices (handled above), we don't
  1332  			// target the middle of a function.
  1333  			continue
  1334  		}
  1335  		if t >= sym.SDWARFSECT {
  1336  			continue // no need to add label for DWARF symbols
  1337  		}
  1338  		if ldr.AttrSpecial(s) || !ldr.TopLevelSym(s) {
  1339  			// no need to add label for special symbols and non-top-level symbols
  1340  			continue
  1341  		}
  1342  		sz := ldr.SymSize(s)
  1343  		if sz <= limit {
  1344  			continue
  1345  		}
  1346  		addLabelSyms(s, limit, sz)
  1347  	}
  1348  
  1349  	// Also for carrier symbols (for which SymSize is 0)
  1350  	for _, ss := range ld.CarrierSymByType {
  1351  		if ss.Sym != 0 && ss.Size > limit {
  1352  			addLabelSyms(ss.Sym, limit, ss.Size)
  1353  		}
  1354  	}
  1355  }
  1356  
  1357  // offsetLabelName returns the name of the "label" symbol used for a
  1358  // relocation targeting s+off. The label symbols is used on Darwin/Windows
  1359  // when external linking, so that the addend fits in a Mach-O/PE relocation.
  1360  func offsetLabelName(ldr *loader.Loader, s loader.Sym, off int64) string {
  1361  	if off>>20<<20 == off {
  1362  		return fmt.Sprintf("%s+%dMB", ldr.SymExtname(s), off>>20)
  1363  	}
  1364  	return fmt.Sprintf("%s+%d", ldr.SymExtname(s), off)
  1365  }
  1366  
  1367  // Convert the direct jump relocation r to refer to a trampoline if the target is too far.
  1368  func trampoline(ctxt *ld.Link, ldr *loader.Loader, ri int, rs, s loader.Sym) {
  1369  	relocs := ldr.Relocs(s)
  1370  	r := relocs.At(ri)
  1371  	const pcrel = 1
  1372  	switch r.Type() {
  1373  	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_CALL26),
  1374  		objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_JUMP26),
  1375  		objabi.MachoRelocOffset + ld.MACHO_ARM64_RELOC_BRANCH26*2 + pcrel:
  1376  		// Host object relocations that will be turned into a PLT call.
  1377  		// The PLT may be too far. Insert a trampoline for them.
  1378  		fallthrough
  1379  	case objabi.R_CALLARM64:
  1380  		var t int64
  1381  		// ldr.SymValue(rs) == 0 indicates a cross-package jump to a function that is not yet
  1382  		// laid out. Conservatively use a trampoline. This should be rare, as we lay out packages
  1383  		// in dependency order.
  1384  		if ldr.SymValue(rs) != 0 {
  1385  			t = ldr.SymValue(rs) + r.Add() - (ldr.SymValue(s) + int64(r.Off()))
  1386  		}
  1387  		if t >= 1<<27 || t < -1<<27 || ldr.SymValue(rs) == 0 || (*ld.FlagDebugTramp > 1 && (ldr.SymPkg(s) == "" || ldr.SymPkg(s) != ldr.SymPkg(rs))) {
  1388  			// direct call too far, need to insert trampoline.
  1389  			// look up existing trampolines first. if we found one within the range
  1390  			// of direct call, we can reuse it. otherwise create a new one.
  1391  			var tramp loader.Sym
  1392  			for i := 0; ; i++ {
  1393  				oName := ldr.SymName(rs)
  1394  				name := oName + fmt.Sprintf("%+x-tramp%d", r.Add(), i)
  1395  				tramp = ldr.LookupOrCreateSym(name, ldr.SymVersion(rs))
  1396  				ldr.SetAttrReachable(tramp, true)
  1397  				if ldr.SymType(tramp) == sym.SDYNIMPORT {
  1398  					// don't reuse trampoline defined in other module
  1399  					continue
  1400  				}
  1401  				if oName == "runtime.deferreturn" {
  1402  					ldr.SetIsDeferReturnTramp(tramp, true)
  1403  				}
  1404  				if ldr.SymValue(tramp) == 0 {
  1405  					// either the trampoline does not exist -- we need to create one,
  1406  					// or found one the address which is not assigned -- this will be
  1407  					// laid down immediately after the current function. use this one.
  1408  					break
  1409  				}
  1410  
  1411  				t = ldr.SymValue(tramp) - (ldr.SymValue(s) + int64(r.Off()))
  1412  				if t >= -1<<27 && t < 1<<27 {
  1413  					// found an existing trampoline that is not too far
  1414  					// we can just use it
  1415  					break
  1416  				}
  1417  			}
  1418  			if ldr.SymType(tramp) == 0 {
  1419  				// trampoline does not exist, create one
  1420  				trampb := ldr.MakeSymbolUpdater(tramp)
  1421  				ctxt.AddTramp(trampb, ldr.SymType(s))
  1422  				if ldr.SymType(rs) == sym.SDYNIMPORT {
  1423  					if r.Add() != 0 {
  1424  						ctxt.Errorf(s, "nonzero addend for DYNIMPORT call: %v+%d", ldr.SymName(rs), r.Add())
  1425  					}
  1426  					gentrampgot(ctxt, ldr, trampb, rs)
  1427  				} else {
  1428  					gentramp(ctxt, ldr, trampb, rs, r.Add())
  1429  				}
  1430  			}
  1431  			// modify reloc to point to tramp, which will be resolved later
  1432  			sb := ldr.MakeSymbolUpdater(s)
  1433  			relocs := sb.Relocs()
  1434  			r := relocs.At(ri)
  1435  			r.SetSym(tramp)
  1436  			r.SetAdd(0) // clear the offset embedded in the instruction
  1437  		}
  1438  	default:
  1439  		ctxt.Errorf(s, "trampoline called with non-jump reloc: %d (%s)", r.Type(), sym.RelocName(ctxt.Arch, r.Type()))
  1440  	}
  1441  }
  1442  
  1443  // generate a trampoline to target+offset.
  1444  func gentramp(ctxt *ld.Link, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) {
  1445  	tramp.SetSize(12) // 3 instructions
  1446  	P := make([]byte, tramp.Size())
  1447  	o1 := uint32(0x90000010) // adrp x16, target
  1448  	o2 := uint32(0x91000210) // add x16, pc-relative-offset
  1449  	o3 := uint32(0xd61f0200) // br x16
  1450  	ctxt.Arch.ByteOrder.PutUint32(P, o1)
  1451  	ctxt.Arch.ByteOrder.PutUint32(P[4:], o2)
  1452  	ctxt.Arch.ByteOrder.PutUint32(P[8:], o3)
  1453  	tramp.SetData(P)
  1454  
  1455  	r, _ := tramp.AddRel(objabi.R_ADDRARM64)
  1456  	r.SetSiz(8)
  1457  	r.SetSym(target)
  1458  	r.SetAdd(offset)
  1459  }
  1460  
  1461  // generate a trampoline to target+offset for a DYNIMPORT symbol via GOT.
  1462  func gentrampgot(ctxt *ld.Link, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym) {
  1463  	tramp.SetSize(12) // 3 instructions
  1464  	P := make([]byte, tramp.Size())
  1465  	o1 := uint32(0x90000010) // adrp x16, target@GOT
  1466  	o2 := uint32(0xf9400210) // ldr x16, [x16, offset]
  1467  	o3 := uint32(0xd61f0200) // br x16
  1468  	ctxt.Arch.ByteOrder.PutUint32(P, o1)
  1469  	ctxt.Arch.ByteOrder.PutUint32(P[4:], o2)
  1470  	ctxt.Arch.ByteOrder.PutUint32(P[8:], o3)
  1471  	tramp.SetData(P)
  1472  
  1473  	r, _ := tramp.AddRel(objabi.R_ARM64_GOTPCREL)
  1474  	r.SetSiz(8)
  1475  	r.SetSym(target)
  1476  }
  1477  

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