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      1 // Inferno utils/6l/asm.c
      2 // http://code.google.com/p/inferno-os/source/browse/utils/6l/asm.c
      3 //
      4 //	Copyright  1994-1999 Lucent Technologies Inc.  All rights reserved.
      5 //	Portions Copyright  1995-1997 C H Forsyth (forsyth (a] 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 (a] 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 amd64
     32 
     33 import (
     34 	"cmd/internal/obj"
     35 	"cmd/link/internal/ld"
     36 	"debug/elf"
     37 	"fmt"
     38 	"log"
     39 )
     40 
     41 func PADDR(x uint32) uint32 {
     42 	return x &^ 0x80000000
     43 }
     44 
     45 var zeroes string
     46 
     47 func Addcall(ctxt *ld.Link, s *ld.LSym, t *ld.LSym) int64 {
     48 	s.Reachable = true
     49 	i := s.Size
     50 	s.Size += 4
     51 	ld.Symgrow(ctxt, s, s.Size)
     52 	r := ld.Addrel(s)
     53 	r.Sym = t
     54 	r.Off = int32(i)
     55 	r.Type = obj.R_CALL
     56 	r.Siz = 4
     57 	return i + int64(r.Siz)
     58 }
     59 
     60 func gentext() {
     61 	if !ld.DynlinkingGo() {
     62 		return
     63 	}
     64 	addmoduledata := ld.Linklookup(ld.Ctxt, "runtime.addmoduledata", 0)
     65 	if addmoduledata.Type == obj.STEXT {
     66 		// we're linking a module containing the runtime -> no need for
     67 		// an init function
     68 		return
     69 	}
     70 	addmoduledata.Reachable = true
     71 	initfunc := ld.Linklookup(ld.Ctxt, "go.link.addmoduledata", 0)
     72 	initfunc.Type = obj.STEXT
     73 	initfunc.Local = true
     74 	initfunc.Reachable = true
     75 	o := func(op ...uint8) {
     76 		for _, op1 := range op {
     77 			ld.Adduint8(ld.Ctxt, initfunc, op1)
     78 		}
     79 	}
     80 	// 0000000000000000 <local.dso_init>:
     81 	//    0:	48 8d 3d 00 00 00 00 	lea    0x0(%rip),%rdi        # 7 <local.dso_init+0x7>
     82 	// 			3: R_X86_64_PC32	runtime.firstmoduledata-0x4
     83 	o(0x48, 0x8d, 0x3d)
     84 	ld.Addpcrelplus(ld.Ctxt, initfunc, ld.Linklookup(ld.Ctxt, "runtime.firstmoduledata", 0), 0)
     85 	//    7:	e8 00 00 00 00       	callq  c <local.dso_init+0xc>
     86 	// 			8: R_X86_64_PLT32	runtime.addmoduledata-0x4
     87 	o(0xe8)
     88 	Addcall(ld.Ctxt, initfunc, addmoduledata)
     89 	//    c:	c3                   	retq
     90 	o(0xc3)
     91 	if ld.Ctxt.Etextp != nil {
     92 		ld.Ctxt.Etextp.Next = initfunc
     93 	} else {
     94 		ld.Ctxt.Textp = initfunc
     95 	}
     96 	ld.Ctxt.Etextp = initfunc
     97 	initarray_entry := ld.Linklookup(ld.Ctxt, "go.link.addmoduledatainit", 0)
     98 	initarray_entry.Reachable = true
     99 	initarray_entry.Local = true
    100 	initarray_entry.Type = obj.SINITARR
    101 	ld.Addaddr(ld.Ctxt, initarray_entry, initfunc)
    102 }
    103 
    104 func adddynrela(rela *ld.LSym, s *ld.LSym, r *ld.Reloc) {
    105 	ld.Addaddrplus(ld.Ctxt, rela, s, int64(r.Off))
    106 	ld.Adduint64(ld.Ctxt, rela, ld.R_X86_64_RELATIVE)
    107 	ld.Addaddrplus(ld.Ctxt, rela, r.Sym, r.Add) // Addend
    108 }
    109 
    110 func adddynrel(s *ld.LSym, r *ld.Reloc) {
    111 	targ := r.Sym
    112 	ld.Ctxt.Cursym = s
    113 
    114 	switch r.Type {
    115 	default:
    116 		if r.Type >= 256 {
    117 			ld.Diag("unexpected relocation type %d", r.Type)
    118 			return
    119 		}
    120 
    121 		// Handle relocations found in ELF object files.
    122 	case 256 + ld.R_X86_64_PC32:
    123 		if targ.Type == obj.SDYNIMPORT {
    124 			ld.Diag("unexpected R_X86_64_PC32 relocation for dynamic symbol %s", targ.Name)
    125 		}
    126 		if targ.Type == 0 || targ.Type == obj.SXREF {
    127 			ld.Diag("unknown symbol %s in pcrel", targ.Name)
    128 		}
    129 		r.Type = obj.R_PCREL
    130 		r.Add += 4
    131 		return
    132 
    133 	case 256 + ld.R_X86_64_PLT32:
    134 		r.Type = obj.R_PCREL
    135 		r.Add += 4
    136 		if targ.Type == obj.SDYNIMPORT {
    137 			addpltsym(targ)
    138 			r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
    139 			r.Add += int64(targ.Plt)
    140 		}
    141 
    142 		return
    143 
    144 	case 256 + ld.R_X86_64_GOTPCREL:
    145 		if targ.Type != obj.SDYNIMPORT {
    146 			// have symbol
    147 			if r.Off >= 2 && s.P[r.Off-2] == 0x8b {
    148 				// turn MOVQ of GOT entry into LEAQ of symbol itself
    149 				s.P[r.Off-2] = 0x8d
    150 
    151 				r.Type = obj.R_PCREL
    152 				r.Add += 4
    153 				return
    154 			}
    155 		}
    156 
    157 		// fall back to using GOT and hope for the best (CMOV*)
    158 		// TODO: just needs relocation, no need to put in .dynsym
    159 		addgotsym(targ)
    160 
    161 		r.Type = obj.R_PCREL
    162 		r.Sym = ld.Linklookup(ld.Ctxt, ".got", 0)
    163 		r.Add += 4
    164 		r.Add += int64(targ.Got)
    165 		return
    166 
    167 	case 256 + ld.R_X86_64_64:
    168 		if targ.Type == obj.SDYNIMPORT {
    169 			ld.Diag("unexpected R_X86_64_64 relocation for dynamic symbol %s", targ.Name)
    170 		}
    171 		r.Type = obj.R_ADDR
    172 		return
    173 
    174 	// Handle relocations found in Mach-O object files.
    175 	case 512 + ld.MACHO_X86_64_RELOC_UNSIGNED*2 + 0,
    176 		512 + ld.MACHO_X86_64_RELOC_SIGNED*2 + 0,
    177 		512 + ld.MACHO_X86_64_RELOC_BRANCH*2 + 0:
    178 		// TODO: What is the difference between all these?
    179 		r.Type = obj.R_ADDR
    180 
    181 		if targ.Type == obj.SDYNIMPORT {
    182 			ld.Diag("unexpected reloc for dynamic symbol %s", targ.Name)
    183 		}
    184 		return
    185 
    186 	case 512 + ld.MACHO_X86_64_RELOC_BRANCH*2 + 1:
    187 		if targ.Type == obj.SDYNIMPORT {
    188 			addpltsym(targ)
    189 			r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
    190 			r.Add = int64(targ.Plt)
    191 			r.Type = obj.R_PCREL
    192 			return
    193 		}
    194 		fallthrough
    195 
    196 		// fall through
    197 	case 512 + ld.MACHO_X86_64_RELOC_UNSIGNED*2 + 1,
    198 		512 + ld.MACHO_X86_64_RELOC_SIGNED*2 + 1,
    199 		512 + ld.MACHO_X86_64_RELOC_SIGNED_1*2 + 1,
    200 		512 + ld.MACHO_X86_64_RELOC_SIGNED_2*2 + 1,
    201 		512 + ld.MACHO_X86_64_RELOC_SIGNED_4*2 + 1:
    202 		r.Type = obj.R_PCREL
    203 
    204 		if targ.Type == obj.SDYNIMPORT {
    205 			ld.Diag("unexpected pc-relative reloc for dynamic symbol %s", targ.Name)
    206 		}
    207 		return
    208 
    209 	case 512 + ld.MACHO_X86_64_RELOC_GOT_LOAD*2 + 1:
    210 		if targ.Type != obj.SDYNIMPORT {
    211 			// have symbol
    212 			// turn MOVQ of GOT entry into LEAQ of symbol itself
    213 			if r.Off < 2 || s.P[r.Off-2] != 0x8b {
    214 				ld.Diag("unexpected GOT_LOAD reloc for non-dynamic symbol %s", targ.Name)
    215 				return
    216 			}
    217 
    218 			s.P[r.Off-2] = 0x8d
    219 			r.Type = obj.R_PCREL
    220 			return
    221 		}
    222 		fallthrough
    223 
    224 		// fall through
    225 	case 512 + ld.MACHO_X86_64_RELOC_GOT*2 + 1:
    226 		if targ.Type != obj.SDYNIMPORT {
    227 			ld.Diag("unexpected GOT reloc for non-dynamic symbol %s", targ.Name)
    228 		}
    229 		addgotsym(targ)
    230 		r.Type = obj.R_PCREL
    231 		r.Sym = ld.Linklookup(ld.Ctxt, ".got", 0)
    232 		r.Add += int64(targ.Got)
    233 		return
    234 	}
    235 
    236 	// Handle references to ELF symbols from our own object files.
    237 	if targ.Type != obj.SDYNIMPORT {
    238 		return
    239 	}
    240 
    241 	switch r.Type {
    242 	case obj.R_CALL,
    243 		obj.R_PCREL:
    244 		if ld.HEADTYPE == obj.Hwindows {
    245 			// nothing to do, the relocation will be laid out in pereloc1
    246 			return
    247 		} else {
    248 			// for both ELF and Mach-O
    249 			addpltsym(targ)
    250 			r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
    251 			r.Add = int64(targ.Plt)
    252 			return
    253 		}
    254 
    255 	case obj.R_ADDR:
    256 		if s.Type == obj.STEXT && ld.Iself {
    257 			if ld.HEADTYPE == obj.Hsolaris {
    258 				addpltsym(targ)
    259 				r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
    260 				r.Add += int64(targ.Plt)
    261 				return
    262 			}
    263 			// The code is asking for the address of an external
    264 			// function.  We provide it with the address of the
    265 			// correspondent GOT symbol.
    266 			addgotsym(targ)
    267 
    268 			r.Sym = ld.Linklookup(ld.Ctxt, ".got", 0)
    269 			r.Add += int64(targ.Got)
    270 			return
    271 		}
    272 
    273 		if s.Type != obj.SDATA {
    274 			break
    275 		}
    276 		if ld.Iself {
    277 			ld.Adddynsym(ld.Ctxt, targ)
    278 			rela := ld.Linklookup(ld.Ctxt, ".rela", 0)
    279 			ld.Addaddrplus(ld.Ctxt, rela, s, int64(r.Off))
    280 			if r.Siz == 8 {
    281 				ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(targ.Dynid), ld.R_X86_64_64))
    282 			} else {
    283 				ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(targ.Dynid), ld.R_X86_64_32))
    284 			}
    285 			ld.Adduint64(ld.Ctxt, rela, uint64(r.Add))
    286 			r.Type = 256 // ignore during relocsym
    287 			return
    288 		}
    289 
    290 		if ld.HEADTYPE == obj.Hdarwin && s.Size == int64(ld.Thearch.Ptrsize) && r.Off == 0 {
    291 			// Mach-O relocations are a royal pain to lay out.
    292 			// They use a compact stateful bytecode representation
    293 			// that is too much bother to deal with.
    294 			// Instead, interpret the C declaration
    295 			//	void *_Cvar_stderr = &stderr;
    296 			// as making _Cvar_stderr the name of a GOT entry
    297 			// for stderr.  This is separate from the usual GOT entry,
    298 			// just in case the C code assigns to the variable,
    299 			// and of course it only works for single pointers,
    300 			// but we only need to support cgo and that's all it needs.
    301 			ld.Adddynsym(ld.Ctxt, targ)
    302 
    303 			got := ld.Linklookup(ld.Ctxt, ".got", 0)
    304 			s.Type = got.Type | obj.SSUB
    305 			s.Outer = got
    306 			s.Sub = got.Sub
    307 			got.Sub = s
    308 			s.Value = got.Size
    309 			ld.Adduint64(ld.Ctxt, got, 0)
    310 			ld.Adduint32(ld.Ctxt, ld.Linklookup(ld.Ctxt, ".linkedit.got", 0), uint32(targ.Dynid))
    311 			r.Type = 256 // ignore during relocsym
    312 			return
    313 		}
    314 
    315 		if ld.HEADTYPE == obj.Hwindows {
    316 			// nothing to do, the relocation will be laid out in pereloc1
    317 			return
    318 		}
    319 	}
    320 
    321 	ld.Ctxt.Cursym = s
    322 	ld.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
    323 }
    324 
    325 func elfreloc1(r *ld.Reloc, sectoff int64) int {
    326 	ld.Thearch.Vput(uint64(sectoff))
    327 
    328 	elfsym := r.Xsym.Elfsym
    329 	switch r.Type {
    330 	default:
    331 		return -1
    332 
    333 	case obj.R_ADDR:
    334 		if r.Siz == 4 {
    335 			ld.Thearch.Vput(ld.R_X86_64_32 | uint64(elfsym)<<32)
    336 		} else if r.Siz == 8 {
    337 			ld.Thearch.Vput(ld.R_X86_64_64 | uint64(elfsym)<<32)
    338 		} else {
    339 			return -1
    340 		}
    341 
    342 	case obj.R_TLS_LE:
    343 		if r.Siz == 4 {
    344 			ld.Thearch.Vput(ld.R_X86_64_TPOFF32 | uint64(elfsym)<<32)
    345 		} else {
    346 			return -1
    347 		}
    348 
    349 	case obj.R_TLS_IE:
    350 		if r.Siz == 4 {
    351 			ld.Thearch.Vput(ld.R_X86_64_GOTTPOFF | uint64(elfsym)<<32)
    352 		} else {
    353 			return -1
    354 		}
    355 
    356 	case obj.R_CALL:
    357 		if r.Siz == 4 {
    358 			if r.Xsym.Type == obj.SDYNIMPORT {
    359 				if ld.DynlinkingGo() {
    360 					ld.Thearch.Vput(ld.R_X86_64_PLT32 | uint64(elfsym)<<32)
    361 				} else {
    362 					ld.Thearch.Vput(ld.R_X86_64_GOTPCREL | uint64(elfsym)<<32)
    363 				}
    364 			} else {
    365 				ld.Thearch.Vput(ld.R_X86_64_PC32 | uint64(elfsym)<<32)
    366 			}
    367 		} else {
    368 			return -1
    369 		}
    370 
    371 	case obj.R_PCREL:
    372 		if r.Siz == 4 {
    373 			if r.Xsym.Type == obj.SDYNIMPORT && r.Xsym.ElfType == elf.STT_FUNC {
    374 				ld.Thearch.Vput(ld.R_X86_64_PLT32 | uint64(elfsym)<<32)
    375 			} else {
    376 				ld.Thearch.Vput(ld.R_X86_64_PC32 | uint64(elfsym)<<32)
    377 			}
    378 		} else {
    379 			return -1
    380 		}
    381 
    382 	case obj.R_GOTPCREL:
    383 		if r.Siz == 4 {
    384 			ld.Thearch.Vput(ld.R_X86_64_GOTPCREL | uint64(elfsym)<<32)
    385 		} else {
    386 			return -1
    387 		}
    388 	}
    389 
    390 	ld.Thearch.Vput(uint64(r.Xadd))
    391 	return 0
    392 }
    393 
    394 func machoreloc1(r *ld.Reloc, sectoff int64) int {
    395 	var v uint32
    396 
    397 	rs := r.Xsym
    398 
    399 	if rs.Type == obj.SHOSTOBJ || r.Type == obj.R_PCREL {
    400 		if rs.Dynid < 0 {
    401 			ld.Diag("reloc %d to non-macho symbol %s type=%d", r.Type, rs.Name, rs.Type)
    402 			return -1
    403 		}
    404 
    405 		v = uint32(rs.Dynid)
    406 		v |= 1 << 27 // external relocation
    407 	} else {
    408 		v = uint32(rs.Sect.Extnum)
    409 		if v == 0 {
    410 			ld.Diag("reloc %d to symbol %s in non-macho section %s type=%d", r.Type, rs.Name, rs.Sect.Name, rs.Type)
    411 			return -1
    412 		}
    413 	}
    414 
    415 	switch r.Type {
    416 	default:
    417 		return -1
    418 
    419 	case obj.R_ADDR:
    420 		v |= ld.MACHO_X86_64_RELOC_UNSIGNED << 28
    421 
    422 	case obj.R_CALL:
    423 		v |= 1 << 24 // pc-relative bit
    424 		v |= ld.MACHO_X86_64_RELOC_BRANCH << 28
    425 
    426 		// NOTE: Only works with 'external' relocation. Forced above.
    427 	case obj.R_PCREL:
    428 		v |= 1 << 24 // pc-relative bit
    429 		v |= ld.MACHO_X86_64_RELOC_SIGNED << 28
    430 	}
    431 
    432 	switch r.Siz {
    433 	default:
    434 		return -1
    435 
    436 	case 1:
    437 		v |= 0 << 25
    438 
    439 	case 2:
    440 		v |= 1 << 25
    441 
    442 	case 4:
    443 		v |= 2 << 25
    444 
    445 	case 8:
    446 		v |= 3 << 25
    447 	}
    448 
    449 	ld.Thearch.Lput(uint32(sectoff))
    450 	ld.Thearch.Lput(v)
    451 	return 0
    452 }
    453 
    454 func pereloc1(r *ld.Reloc, sectoff int64) bool {
    455 	var v uint32
    456 
    457 	rs := r.Xsym
    458 
    459 	if rs.Dynid < 0 {
    460 		ld.Diag("reloc %d to non-coff symbol %s type=%d", r.Type, rs.Name, rs.Type)
    461 		return false
    462 	}
    463 
    464 	ld.Thearch.Lput(uint32(sectoff))
    465 	ld.Thearch.Lput(uint32(rs.Dynid))
    466 
    467 	switch r.Type {
    468 	default:
    469 		return false
    470 
    471 	case obj.R_ADDR:
    472 		if r.Siz == 8 {
    473 			v = ld.IMAGE_REL_AMD64_ADDR64
    474 		} else {
    475 			v = ld.IMAGE_REL_AMD64_ADDR32
    476 		}
    477 
    478 	case obj.R_CALL,
    479 		obj.R_PCREL:
    480 		v = ld.IMAGE_REL_AMD64_REL32
    481 	}
    482 
    483 	ld.Thearch.Wput(uint16(v))
    484 
    485 	return true
    486 }
    487 
    488 func archreloc(r *ld.Reloc, s *ld.LSym, val *int64) int {
    489 	return -1
    490 }
    491 
    492 func archrelocvariant(r *ld.Reloc, s *ld.LSym, t int64) int64 {
    493 	log.Fatalf("unexpected relocation variant")
    494 	return t
    495 }
    496 
    497 func elfsetupplt() {
    498 	plt := ld.Linklookup(ld.Ctxt, ".plt", 0)
    499 	got := ld.Linklookup(ld.Ctxt, ".got.plt", 0)
    500 	if plt.Size == 0 {
    501 		// pushq got+8(IP)
    502 		ld.Adduint8(ld.Ctxt, plt, 0xff)
    503 
    504 		ld.Adduint8(ld.Ctxt, plt, 0x35)
    505 		ld.Addpcrelplus(ld.Ctxt, plt, got, 8)
    506 
    507 		// jmpq got+16(IP)
    508 		ld.Adduint8(ld.Ctxt, plt, 0xff)
    509 
    510 		ld.Adduint8(ld.Ctxt, plt, 0x25)
    511 		ld.Addpcrelplus(ld.Ctxt, plt, got, 16)
    512 
    513 		// nopl 0(AX)
    514 		ld.Adduint32(ld.Ctxt, plt, 0x00401f0f)
    515 
    516 		// assume got->size == 0 too
    517 		ld.Addaddrplus(ld.Ctxt, got, ld.Linklookup(ld.Ctxt, ".dynamic", 0), 0)
    518 
    519 		ld.Adduint64(ld.Ctxt, got, 0)
    520 		ld.Adduint64(ld.Ctxt, got, 0)
    521 	}
    522 }
    523 
    524 func addpltsym(s *ld.LSym) {
    525 	if s.Plt >= 0 {
    526 		return
    527 	}
    528 
    529 	ld.Adddynsym(ld.Ctxt, s)
    530 
    531 	if ld.Iself {
    532 		plt := ld.Linklookup(ld.Ctxt, ".plt", 0)
    533 		got := ld.Linklookup(ld.Ctxt, ".got.plt", 0)
    534 		rela := ld.Linklookup(ld.Ctxt, ".rela.plt", 0)
    535 		if plt.Size == 0 {
    536 			elfsetupplt()
    537 		}
    538 
    539 		// jmpq *got+size(IP)
    540 		ld.Adduint8(ld.Ctxt, plt, 0xff)
    541 
    542 		ld.Adduint8(ld.Ctxt, plt, 0x25)
    543 		ld.Addpcrelplus(ld.Ctxt, plt, got, got.Size)
    544 
    545 		// add to got: pointer to current pos in plt
    546 		ld.Addaddrplus(ld.Ctxt, got, plt, plt.Size)
    547 
    548 		// pushq $x
    549 		ld.Adduint8(ld.Ctxt, plt, 0x68)
    550 
    551 		ld.Adduint32(ld.Ctxt, plt, uint32((got.Size-24-8)/8))
    552 
    553 		// jmpq .plt
    554 		ld.Adduint8(ld.Ctxt, plt, 0xe9)
    555 
    556 		ld.Adduint32(ld.Ctxt, plt, uint32(-(plt.Size + 4)))
    557 
    558 		// rela
    559 		ld.Addaddrplus(ld.Ctxt, rela, got, got.Size-8)
    560 
    561 		ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_X86_64_JMP_SLOT))
    562 		ld.Adduint64(ld.Ctxt, rela, 0)
    563 
    564 		s.Plt = int32(plt.Size - 16)
    565 	} else if ld.HEADTYPE == obj.Hdarwin {
    566 		// To do lazy symbol lookup right, we're supposed
    567 		// to tell the dynamic loader which library each
    568 		// symbol comes from and format the link info
    569 		// section just so.  I'm too lazy (ha!) to do that
    570 		// so for now we'll just use non-lazy pointers,
    571 		// which don't need to be told which library to use.
    572 		//
    573 		// http://networkpx.blogspot.com/2009/09/about-lcdyldinfoonly-command.html
    574 		// has details about what we're avoiding.
    575 
    576 		addgotsym(s)
    577 		plt := ld.Linklookup(ld.Ctxt, ".plt", 0)
    578 
    579 		ld.Adduint32(ld.Ctxt, ld.Linklookup(ld.Ctxt, ".linkedit.plt", 0), uint32(s.Dynid))
    580 
    581 		// jmpq *got+size(IP)
    582 		s.Plt = int32(plt.Size)
    583 
    584 		ld.Adduint8(ld.Ctxt, plt, 0xff)
    585 		ld.Adduint8(ld.Ctxt, plt, 0x25)
    586 		ld.Addpcrelplus(ld.Ctxt, plt, ld.Linklookup(ld.Ctxt, ".got", 0), int64(s.Got))
    587 	} else {
    588 		ld.Diag("addpltsym: unsupported binary format")
    589 	}
    590 }
    591 
    592 func addgotsym(s *ld.LSym) {
    593 	if s.Got >= 0 {
    594 		return
    595 	}
    596 
    597 	ld.Adddynsym(ld.Ctxt, s)
    598 	got := ld.Linklookup(ld.Ctxt, ".got", 0)
    599 	s.Got = int32(got.Size)
    600 	ld.Adduint64(ld.Ctxt, got, 0)
    601 
    602 	if ld.Iself {
    603 		rela := ld.Linklookup(ld.Ctxt, ".rela", 0)
    604 		ld.Addaddrplus(ld.Ctxt, rela, got, int64(s.Got))
    605 		ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_X86_64_GLOB_DAT))
    606 		ld.Adduint64(ld.Ctxt, rela, 0)
    607 	} else if ld.HEADTYPE == obj.Hdarwin {
    608 		ld.Adduint32(ld.Ctxt, ld.Linklookup(ld.Ctxt, ".linkedit.got", 0), uint32(s.Dynid))
    609 	} else {
    610 		ld.Diag("addgotsym: unsupported binary format")
    611 	}
    612 }
    613 
    614 func asmb() {
    615 	if ld.Debug['v'] != 0 {
    616 		fmt.Fprintf(&ld.Bso, "%5.2f asmb\n", obj.Cputime())
    617 	}
    618 	ld.Bso.Flush()
    619 
    620 	if ld.Debug['v'] != 0 {
    621 		fmt.Fprintf(&ld.Bso, "%5.2f codeblk\n", obj.Cputime())
    622 	}
    623 	ld.Bso.Flush()
    624 
    625 	if ld.Iself {
    626 		ld.Asmbelfsetup()
    627 	}
    628 
    629 	sect := ld.Segtext.Sect
    630 	ld.Cseek(int64(sect.Vaddr - ld.Segtext.Vaddr + ld.Segtext.Fileoff))
    631 	ld.Codeblk(int64(sect.Vaddr), int64(sect.Length))
    632 	for sect = sect.Next; sect != nil; sect = sect.Next {
    633 		ld.Cseek(int64(sect.Vaddr - ld.Segtext.Vaddr + ld.Segtext.Fileoff))
    634 		ld.Datblk(int64(sect.Vaddr), int64(sect.Length))
    635 	}
    636 
    637 	if ld.Segrodata.Filelen > 0 {
    638 		if ld.Debug['v'] != 0 {
    639 			fmt.Fprintf(&ld.Bso, "%5.2f rodatblk\n", obj.Cputime())
    640 		}
    641 		ld.Bso.Flush()
    642 
    643 		ld.Cseek(int64(ld.Segrodata.Fileoff))
    644 		ld.Datblk(int64(ld.Segrodata.Vaddr), int64(ld.Segrodata.Filelen))
    645 	}
    646 
    647 	if ld.Debug['v'] != 0 {
    648 		fmt.Fprintf(&ld.Bso, "%5.2f datblk\n", obj.Cputime())
    649 	}
    650 	ld.Bso.Flush()
    651 
    652 	ld.Cseek(int64(ld.Segdata.Fileoff))
    653 	ld.Datblk(int64(ld.Segdata.Vaddr), int64(ld.Segdata.Filelen))
    654 
    655 	machlink := int64(0)
    656 	if ld.HEADTYPE == obj.Hdarwin {
    657 		if ld.Debug['v'] != 0 {
    658 			fmt.Fprintf(&ld.Bso, "%5.2f dwarf\n", obj.Cputime())
    659 		}
    660 
    661 		dwarfoff := ld.Rnd(int64(uint64(ld.HEADR)+ld.Segtext.Length), int64(ld.INITRND)) + ld.Rnd(int64(ld.Segdata.Filelen), int64(ld.INITRND))
    662 		ld.Cseek(dwarfoff)
    663 
    664 		ld.Segdwarf.Fileoff = uint64(ld.Cpos())
    665 		ld.Dwarfemitdebugsections()
    666 		ld.Segdwarf.Filelen = uint64(ld.Cpos()) - ld.Segdwarf.Fileoff
    667 
    668 		machlink = ld.Domacholink()
    669 	}
    670 
    671 	switch ld.HEADTYPE {
    672 	default:
    673 		ld.Diag("unknown header type %d", ld.HEADTYPE)
    674 		fallthrough
    675 
    676 	case obj.Hplan9,
    677 		obj.Helf:
    678 		break
    679 
    680 	case obj.Hdarwin:
    681 		ld.Debug['8'] = 1 /* 64-bit addresses */
    682 
    683 	case obj.Hlinux,
    684 		obj.Hfreebsd,
    685 		obj.Hnetbsd,
    686 		obj.Hopenbsd,
    687 		obj.Hdragonfly,
    688 		obj.Hsolaris:
    689 		ld.Debug['8'] = 1 /* 64-bit addresses */
    690 
    691 	case obj.Hnacl,
    692 		obj.Hwindows:
    693 		break
    694 	}
    695 
    696 	ld.Symsize = 0
    697 	ld.Spsize = 0
    698 	ld.Lcsize = 0
    699 	symo := int64(0)
    700 	if ld.Debug['s'] == 0 {
    701 		if ld.Debug['v'] != 0 {
    702 			fmt.Fprintf(&ld.Bso, "%5.2f sym\n", obj.Cputime())
    703 		}
    704 		ld.Bso.Flush()
    705 		switch ld.HEADTYPE {
    706 		default:
    707 		case obj.Hplan9,
    708 			obj.Helf:
    709 			ld.Debug['s'] = 1
    710 			symo = int64(ld.Segdata.Fileoff + ld.Segdata.Filelen)
    711 
    712 		case obj.Hdarwin:
    713 			symo = int64(ld.Segdwarf.Fileoff + uint64(ld.Rnd(int64(ld.Segdwarf.Filelen), int64(ld.INITRND))) + uint64(machlink))
    714 
    715 		case obj.Hlinux,
    716 			obj.Hfreebsd,
    717 			obj.Hnetbsd,
    718 			obj.Hopenbsd,
    719 			obj.Hdragonfly,
    720 			obj.Hsolaris,
    721 			obj.Hnacl:
    722 			symo = int64(ld.Segdata.Fileoff + ld.Segdata.Filelen)
    723 			symo = ld.Rnd(symo, int64(ld.INITRND))
    724 
    725 		case obj.Hwindows:
    726 			symo = int64(ld.Segdata.Fileoff + ld.Segdata.Filelen)
    727 			symo = ld.Rnd(symo, ld.PEFILEALIGN)
    728 		}
    729 
    730 		ld.Cseek(symo)
    731 		switch ld.HEADTYPE {
    732 		default:
    733 			if ld.Iself {
    734 				ld.Cseek(symo)
    735 				ld.Asmelfsym()
    736 				ld.Cflush()
    737 				ld.Cwrite(ld.Elfstrdat)
    738 
    739 				if ld.Debug['v'] != 0 {
    740 					fmt.Fprintf(&ld.Bso, "%5.2f dwarf\n", obj.Cputime())
    741 				}
    742 
    743 				ld.Dwarfemitdebugsections()
    744 
    745 				if ld.Linkmode == ld.LinkExternal {
    746 					ld.Elfemitreloc()
    747 				}
    748 			}
    749 
    750 		case obj.Hplan9:
    751 			ld.Asmplan9sym()
    752 			ld.Cflush()
    753 
    754 			sym := ld.Linklookup(ld.Ctxt, "pclntab", 0)
    755 			if sym != nil {
    756 				ld.Lcsize = int32(len(sym.P))
    757 				for i := 0; int32(i) < ld.Lcsize; i++ {
    758 					ld.Cput(uint8(sym.P[i]))
    759 				}
    760 
    761 				ld.Cflush()
    762 			}
    763 
    764 		case obj.Hwindows:
    765 			if ld.Debug['v'] != 0 {
    766 				fmt.Fprintf(&ld.Bso, "%5.2f dwarf\n", obj.Cputime())
    767 			}
    768 
    769 			ld.Dwarfemitdebugsections()
    770 
    771 		case obj.Hdarwin:
    772 			if ld.Linkmode == ld.LinkExternal {
    773 				ld.Machoemitreloc()
    774 			}
    775 		}
    776 	}
    777 
    778 	if ld.Debug['v'] != 0 {
    779 		fmt.Fprintf(&ld.Bso, "%5.2f headr\n", obj.Cputime())
    780 	}
    781 	ld.Bso.Flush()
    782 	ld.Cseek(0)
    783 	switch ld.HEADTYPE {
    784 	default:
    785 	case obj.Hplan9: /* plan9 */
    786 		magic := int32(4*26*26 + 7)
    787 
    788 		magic |= 0x00008000                  /* fat header */
    789 		ld.Lputb(uint32(magic))              /* magic */
    790 		ld.Lputb(uint32(ld.Segtext.Filelen)) /* sizes */
    791 		ld.Lputb(uint32(ld.Segdata.Filelen))
    792 		ld.Lputb(uint32(ld.Segdata.Length - ld.Segdata.Filelen))
    793 		ld.Lputb(uint32(ld.Symsize)) /* nsyms */
    794 		vl := ld.Entryvalue()
    795 		ld.Lputb(PADDR(uint32(vl))) /* va of entry */
    796 		ld.Lputb(uint32(ld.Spsize)) /* sp offsets */
    797 		ld.Lputb(uint32(ld.Lcsize)) /* line offsets */
    798 		ld.Vputb(uint64(vl))        /* va of entry */
    799 
    800 	case obj.Hdarwin:
    801 		ld.Asmbmacho()
    802 
    803 	case obj.Hlinux,
    804 		obj.Hfreebsd,
    805 		obj.Hnetbsd,
    806 		obj.Hopenbsd,
    807 		obj.Hdragonfly,
    808 		obj.Hsolaris,
    809 		obj.Hnacl:
    810 		ld.Asmbelf(symo)
    811 
    812 	case obj.Hwindows:
    813 		ld.Asmbpe()
    814 	}
    815 
    816 	ld.Cflush()
    817 }
    818