1 // Inferno utils/5l/asm.c 2 // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/5l/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 arm 32 33 import ( 34 "cmd/internal/objabi" 35 "cmd/internal/sys" 36 "cmd/link/internal/ld" 37 "cmd/link/internal/sym" 38 "debug/elf" 39 "fmt" 40 "log" 41 ) 42 43 // This assembler: 44 // 45 // .align 2 46 // local.dso_init: 47 // ldr r0, .Lmoduledata 48 // .Lloadfrom: 49 // ldr r0, [r0] 50 // b runtime.addmoduledata@plt 51 // .align 2 52 // .Lmoduledata: 53 // .word local.moduledata(GOT_PREL) + (. - (.Lloadfrom + 4)) 54 // assembles to: 55 // 56 // 00000000 <local.dso_init>: 57 // 0: e59f0004 ldr r0, [pc, #4] ; c <local.dso_init+0xc> 58 // 4: e5900000 ldr r0, [r0] 59 // 8: eafffffe b 0 <runtime.addmoduledata> 60 // 8: R_ARM_JUMP24 runtime.addmoduledata 61 // c: 00000004 .word 0x00000004 62 // c: R_ARM_GOT_PREL local.moduledata 63 64 func gentext(ctxt *ld.Link) { 65 if !ctxt.DynlinkingGo() { 66 return 67 } 68 addmoduledata := ctxt.Syms.Lookup("runtime.addmoduledata", 0) 69 if addmoduledata.Type == sym.STEXT && ctxt.BuildMode != ld.BuildModePlugin { 70 // we're linking a module containing the runtime -> no need for 71 // an init function 72 return 73 } 74 addmoduledata.Attr |= sym.AttrReachable 75 initfunc := ctxt.Syms.Lookup("go.link.addmoduledata", 0) 76 initfunc.Type = sym.STEXT 77 initfunc.Attr |= sym.AttrLocal 78 initfunc.Attr |= sym.AttrReachable 79 o := func(op uint32) { 80 initfunc.AddUint32(ctxt.Arch, op) 81 } 82 o(0xe59f0004) 83 o(0xe08f0000) 84 85 o(0xeafffffe) 86 rel := initfunc.AddRel() 87 rel.Off = 8 88 rel.Siz = 4 89 rel.Sym = ctxt.Syms.Lookup("runtime.addmoduledata", 0) 90 rel.Type = objabi.R_CALLARM 91 rel.Add = 0xeafffffe // vomit 92 93 o(0x00000000) 94 rel = initfunc.AddRel() 95 rel.Off = 12 96 rel.Siz = 4 97 rel.Sym = ctxt.Moduledata 98 rel.Type = objabi.R_PCREL 99 rel.Add = 4 100 101 if ctxt.BuildMode == ld.BuildModePlugin { 102 ctxt.Textp = append(ctxt.Textp, addmoduledata) 103 } 104 ctxt.Textp = append(ctxt.Textp, initfunc) 105 initarray_entry := ctxt.Syms.Lookup("go.link.addmoduledatainit", 0) 106 initarray_entry.Attr |= sym.AttrReachable 107 initarray_entry.Attr |= sym.AttrLocal 108 initarray_entry.Type = sym.SINITARR 109 initarray_entry.AddAddr(ctxt.Arch, initfunc) 110 } 111 112 // Preserve highest 8 bits of a, and do addition to lower 24-bit 113 // of a and b; used to adjust ARM branch instruction's target 114 func braddoff(a int32, b int32) int32 { 115 return int32((uint32(a))&0xff000000 | 0x00ffffff&uint32(a+b)) 116 } 117 118 func adddynrel(ctxt *ld.Link, s *sym.Symbol, r *sym.Reloc) bool { 119 targ := r.Sym 120 121 switch r.Type { 122 default: 123 if r.Type >= 256 { 124 ld.Errorf(s, "unexpected relocation type %d (%s)", r.Type, sym.RelocName(ctxt.Arch, r.Type)) 125 return false 126 } 127 128 // Handle relocations found in ELF object files. 129 case 256 + objabi.RelocType(elf.R_ARM_PLT32): 130 r.Type = objabi.R_CALLARM 131 132 if targ.Type == sym.SDYNIMPORT { 133 addpltsym(ctxt, targ) 134 r.Sym = ctxt.Syms.Lookup(".plt", 0) 135 r.Add = int64(braddoff(int32(r.Add), targ.Plt/4)) 136 } 137 138 return true 139 140 case 256 + objabi.RelocType(elf.R_ARM_THM_PC22): // R_ARM_THM_CALL 141 ld.Exitf("R_ARM_THM_CALL, are you using -marm?") 142 return false 143 144 case 256 + objabi.RelocType(elf.R_ARM_GOT32): // R_ARM_GOT_BREL 145 if targ.Type != sym.SDYNIMPORT { 146 addgotsyminternal(ctxt, targ) 147 } else { 148 addgotsym(ctxt, targ) 149 } 150 151 r.Type = objabi.R_CONST // write r->add during relocsym 152 r.Sym = nil 153 r.Add += int64(targ.Got) 154 return true 155 156 case 256 + objabi.RelocType(elf.R_ARM_GOT_PREL): // GOT(nil) + A - nil 157 if targ.Type != sym.SDYNIMPORT { 158 addgotsyminternal(ctxt, targ) 159 } else { 160 addgotsym(ctxt, targ) 161 } 162 163 r.Type = objabi.R_PCREL 164 r.Sym = ctxt.Syms.Lookup(".got", 0) 165 r.Add += int64(targ.Got) + 4 166 return true 167 168 case 256 + objabi.RelocType(elf.R_ARM_GOTOFF): // R_ARM_GOTOFF32 169 r.Type = objabi.R_GOTOFF 170 171 return true 172 173 case 256 + objabi.RelocType(elf.R_ARM_GOTPC): // R_ARM_BASE_PREL 174 r.Type = objabi.R_PCREL 175 176 r.Sym = ctxt.Syms.Lookup(".got", 0) 177 r.Add += 4 178 return true 179 180 case 256 + objabi.RelocType(elf.R_ARM_CALL): 181 r.Type = objabi.R_CALLARM 182 if targ.Type == sym.SDYNIMPORT { 183 addpltsym(ctxt, targ) 184 r.Sym = ctxt.Syms.Lookup(".plt", 0) 185 r.Add = int64(braddoff(int32(r.Add), targ.Plt/4)) 186 } 187 188 return true 189 190 case 256 + objabi.RelocType(elf.R_ARM_REL32): // R_ARM_REL32 191 r.Type = objabi.R_PCREL 192 193 r.Add += 4 194 return true 195 196 case 256 + objabi.RelocType(elf.R_ARM_ABS32): 197 if targ.Type == sym.SDYNIMPORT { 198 ld.Errorf(s, "unexpected R_ARM_ABS32 relocation for dynamic symbol %s", targ.Name) 199 } 200 r.Type = objabi.R_ADDR 201 return true 202 203 // we can just ignore this, because we are targeting ARM V5+ anyway 204 case 256 + objabi.RelocType(elf.R_ARM_V4BX): 205 if r.Sym != nil { 206 // R_ARM_V4BX is ABS relocation, so this symbol is a dummy symbol, ignore it 207 r.Sym.Type = 0 208 } 209 210 r.Sym = nil 211 return true 212 213 case 256 + objabi.RelocType(elf.R_ARM_PC24), 214 256 + objabi.RelocType(elf.R_ARM_JUMP24): 215 r.Type = objabi.R_CALLARM 216 if targ.Type == sym.SDYNIMPORT { 217 addpltsym(ctxt, targ) 218 r.Sym = ctxt.Syms.Lookup(".plt", 0) 219 r.Add = int64(braddoff(int32(r.Add), targ.Plt/4)) 220 } 221 222 return true 223 } 224 225 // Handle references to ELF symbols from our own object files. 226 if targ.Type != sym.SDYNIMPORT { 227 return true 228 } 229 230 switch r.Type { 231 case objabi.R_CALLARM: 232 addpltsym(ctxt, targ) 233 r.Sym = ctxt.Syms.Lookup(".plt", 0) 234 r.Add = int64(targ.Plt) 235 return true 236 237 case objabi.R_ADDR: 238 if s.Type != sym.SDATA { 239 break 240 } 241 if ctxt.IsELF { 242 ld.Adddynsym(ctxt, targ) 243 rel := ctxt.Syms.Lookup(".rel", 0) 244 rel.AddAddrPlus(ctxt.Arch, s, int64(r.Off)) 245 rel.AddUint32(ctxt.Arch, ld.ELF32_R_INFO(uint32(targ.Dynid), uint32(elf.R_ARM_GLOB_DAT))) // we need a nil + A dynamic reloc 246 r.Type = objabi.R_CONST // write r->add during relocsym 247 r.Sym = nil 248 return true 249 } 250 } 251 252 return false 253 } 254 255 func elfreloc1(ctxt *ld.Link, r *sym.Reloc, sectoff int64) bool { 256 ctxt.Out.Write32(uint32(sectoff)) 257 258 elfsym := r.Xsym.ElfsymForReloc() 259 switch r.Type { 260 default: 261 return false 262 case objabi.R_ADDR: 263 if r.Siz == 4 { 264 ctxt.Out.Write32(uint32(elf.R_ARM_ABS32) | uint32(elfsym)<<8) 265 } else { 266 return false 267 } 268 case objabi.R_PCREL: 269 if r.Siz == 4 { 270 ctxt.Out.Write32(uint32(elf.R_ARM_REL32) | uint32(elfsym)<<8) 271 } else { 272 return false 273 } 274 case objabi.R_CALLARM: 275 if r.Siz == 4 { 276 if r.Add&0xff000000 == 0xeb000000 { // BL 277 ctxt.Out.Write32(uint32(elf.R_ARM_CALL) | uint32(elfsym)<<8) 278 } else { 279 ctxt.Out.Write32(uint32(elf.R_ARM_JUMP24) | uint32(elfsym)<<8) 280 } 281 } else { 282 return false 283 } 284 case objabi.R_TLS_LE: 285 ctxt.Out.Write32(uint32(elf.R_ARM_TLS_LE32) | uint32(elfsym)<<8) 286 case objabi.R_TLS_IE: 287 ctxt.Out.Write32(uint32(elf.R_ARM_TLS_IE32) | uint32(elfsym)<<8) 288 case objabi.R_GOTPCREL: 289 if r.Siz == 4 { 290 ctxt.Out.Write32(uint32(elf.R_ARM_GOT_PREL) | uint32(elfsym)<<8) 291 } else { 292 return false 293 } 294 } 295 296 return true 297 } 298 299 func elfsetupplt(ctxt *ld.Link) { 300 plt := ctxt.Syms.Lookup(".plt", 0) 301 got := ctxt.Syms.Lookup(".got.plt", 0) 302 if plt.Size == 0 { 303 // str lr, [sp, #-4]! 304 plt.AddUint32(ctxt.Arch, 0xe52de004) 305 306 // ldr lr, [pc, #4] 307 plt.AddUint32(ctxt.Arch, 0xe59fe004) 308 309 // add lr, pc, lr 310 plt.AddUint32(ctxt.Arch, 0xe08fe00e) 311 312 // ldr pc, [lr, #8]! 313 plt.AddUint32(ctxt.Arch, 0xe5bef008) 314 315 // .word &GLOBAL_OFFSET_TABLE[0] - . 316 plt.AddPCRelPlus(ctxt.Arch, got, 4) 317 318 // the first .plt entry requires 3 .plt.got entries 319 got.AddUint32(ctxt.Arch, 0) 320 321 got.AddUint32(ctxt.Arch, 0) 322 got.AddUint32(ctxt.Arch, 0) 323 } 324 } 325 326 func machoreloc1(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, sectoff int64) bool { 327 var v uint32 328 329 rs := r.Xsym 330 331 if r.Type == objabi.R_PCREL { 332 if rs.Type == sym.SHOSTOBJ { 333 ld.Errorf(s, "pc-relative relocation of external symbol is not supported") 334 return false 335 } 336 if r.Siz != 4 { 337 return false 338 } 339 340 // emit a pair of "scattered" relocations that 341 // resolve to the difference of section addresses of 342 // the symbol and the instruction 343 // this value is added to the field being relocated 344 o1 := uint32(sectoff) 345 o1 |= 1 << 31 // scattered bit 346 o1 |= ld.MACHO_ARM_RELOC_SECTDIFF << 24 347 o1 |= 2 << 28 // size = 4 348 349 o2 := uint32(0) 350 o2 |= 1 << 31 // scattered bit 351 o2 |= ld.MACHO_ARM_RELOC_PAIR << 24 352 o2 |= 2 << 28 // size = 4 353 354 out.Write32(o1) 355 out.Write32(uint32(ld.Symaddr(rs))) 356 out.Write32(o2) 357 out.Write32(uint32(s.Value + int64(r.Off))) 358 return true 359 } 360 361 if rs.Type == sym.SHOSTOBJ || r.Type == objabi.R_CALLARM { 362 if rs.Dynid < 0 { 363 ld.Errorf(s, "reloc %d (%s) to non-macho symbol %s type=%d (%s)", r.Type, sym.RelocName(arch, r.Type), rs.Name, rs.Type, rs.Type) 364 return false 365 } 366 367 v = uint32(rs.Dynid) 368 v |= 1 << 27 // external relocation 369 } else { 370 v = uint32(rs.Sect.Extnum) 371 if v == 0 { 372 ld.Errorf(s, "reloc %d (%s) to symbol %s in non-macho section %s type=%d (%s)", r.Type, sym.RelocName(arch, r.Type), rs.Name, rs.Sect.Name, rs.Type, rs.Type) 373 return false 374 } 375 } 376 377 switch r.Type { 378 default: 379 return false 380 381 case objabi.R_ADDR: 382 v |= ld.MACHO_GENERIC_RELOC_VANILLA << 28 383 384 case objabi.R_CALLARM: 385 v |= 1 << 24 // pc-relative bit 386 v |= ld.MACHO_ARM_RELOC_BR24 << 28 387 } 388 389 switch r.Siz { 390 default: 391 return false 392 case 1: 393 v |= 0 << 25 394 395 case 2: 396 v |= 1 << 25 397 398 case 4: 399 v |= 2 << 25 400 401 case 8: 402 v |= 3 << 25 403 } 404 405 out.Write32(uint32(sectoff)) 406 out.Write32(v) 407 return true 408 } 409 410 // sign extend a 24-bit integer 411 func signext24(x int64) int32 { 412 return (int32(x) << 8) >> 8 413 } 414 415 // encode an immediate in ARM's imm12 format. copied from ../../../internal/obj/arm/asm5.go 416 func immrot(v uint32) uint32 { 417 for i := 0; i < 16; i++ { 418 if v&^0xff == 0 { 419 return uint32(i<<8) | v | 1<<25 420 } 421 v = v<<2 | v>>30 422 } 423 return 0 424 } 425 426 // Convert the direct jump relocation r to refer to a trampoline if the target is too far 427 func trampoline(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol) { 428 switch r.Type { 429 case objabi.R_CALLARM: 430 // r.Add is the instruction 431 // low 24-bit encodes the target address 432 t := (ld.Symaddr(r.Sym) + int64(signext24(r.Add&0xffffff)*4) - (s.Value + int64(r.Off))) / 4 433 if t > 0x7fffff || t < -0x800000 || (*ld.FlagDebugTramp > 1 && s.File != r.Sym.File) { 434 // direct call too far, need to insert trampoline. 435 // look up existing trampolines first. if we found one within the range 436 // of direct call, we can reuse it. otherwise create a new one. 437 offset := (signext24(r.Add&0xffffff) + 2) * 4 438 var tramp *sym.Symbol 439 for i := 0; ; i++ { 440 name := r.Sym.Name + fmt.Sprintf("%+d-tramp%d", offset, i) 441 tramp = ctxt.Syms.Lookup(name, int(r.Sym.Version)) 442 if tramp.Type == sym.SDYNIMPORT { 443 // don't reuse trampoline defined in other module 444 continue 445 } 446 if tramp.Value == 0 { 447 // either the trampoline does not exist -- we need to create one, 448 // or found one the address which is not assigned -- this will be 449 // laid down immediately after the current function. use this one. 450 break 451 } 452 453 t = (ld.Symaddr(tramp) - 8 - (s.Value + int64(r.Off))) / 4 454 if t >= -0x800000 && t < 0x7fffff { 455 // found an existing trampoline that is not too far 456 // we can just use it 457 break 458 } 459 } 460 if tramp.Type == 0 { 461 // trampoline does not exist, create one 462 ctxt.AddTramp(tramp) 463 if ctxt.DynlinkingGo() { 464 if immrot(uint32(offset)) == 0 { 465 ld.Errorf(s, "odd offset in dynlink direct call: %v+%d", r.Sym, offset) 466 } 467 gentrampdyn(ctxt.Arch, tramp, r.Sym, int64(offset)) 468 } else if ctxt.BuildMode == ld.BuildModeCArchive || ctxt.BuildMode == ld.BuildModeCShared || ctxt.BuildMode == ld.BuildModePIE { 469 gentramppic(ctxt.Arch, tramp, r.Sym, int64(offset)) 470 } else { 471 gentramp(ctxt.Arch, ctxt.LinkMode, tramp, r.Sym, int64(offset)) 472 } 473 } 474 // modify reloc to point to tramp, which will be resolved later 475 r.Sym = tramp 476 r.Add = r.Add&0xff000000 | 0xfffffe // clear the offset embedded in the instruction 477 r.Done = false 478 } 479 default: 480 ld.Errorf(s, "trampoline called with non-jump reloc: %d (%s)", r.Type, sym.RelocName(ctxt.Arch, r.Type)) 481 } 482 } 483 484 // generate a trampoline to target+offset 485 func gentramp(arch *sys.Arch, linkmode ld.LinkMode, tramp, target *sym.Symbol, offset int64) { 486 tramp.Size = 12 // 3 instructions 487 tramp.P = make([]byte, tramp.Size) 488 t := ld.Symaddr(target) + int64(offset) 489 o1 := uint32(0xe5900000 | 11<<12 | 15<<16) // MOVW (R15), R11 // R15 is actual pc + 8 490 o2 := uint32(0xe12fff10 | 11) // JMP (R11) 491 o3 := uint32(t) // WORD $target 492 arch.ByteOrder.PutUint32(tramp.P, o1) 493 arch.ByteOrder.PutUint32(tramp.P[4:], o2) 494 arch.ByteOrder.PutUint32(tramp.P[8:], o3) 495 496 if linkmode == ld.LinkExternal { 497 r := tramp.AddRel() 498 r.Off = 8 499 r.Type = objabi.R_ADDR 500 r.Siz = 4 501 r.Sym = target 502 r.Add = offset 503 } 504 } 505 506 // generate a trampoline to target+offset in position independent code 507 func gentramppic(arch *sys.Arch, tramp, target *sym.Symbol, offset int64) { 508 tramp.Size = 16 // 4 instructions 509 tramp.P = make([]byte, tramp.Size) 510 o1 := uint32(0xe5900000 | 11<<12 | 15<<16 | 4) // MOVW 4(R15), R11 // R15 is actual pc + 8 511 o2 := uint32(0xe0800000 | 11<<12 | 15<<16 | 11) // ADD R15, R11, R11 512 o3 := uint32(0xe12fff10 | 11) // JMP (R11) 513 o4 := uint32(0) // WORD $(target-pc) // filled in with relocation 514 arch.ByteOrder.PutUint32(tramp.P, o1) 515 arch.ByteOrder.PutUint32(tramp.P[4:], o2) 516 arch.ByteOrder.PutUint32(tramp.P[8:], o3) 517 arch.ByteOrder.PutUint32(tramp.P[12:], o4) 518 519 r := tramp.AddRel() 520 r.Off = 12 521 r.Type = objabi.R_PCREL 522 r.Siz = 4 523 r.Sym = target 524 r.Add = offset + 4 525 } 526 527 // generate a trampoline to target+offset in dynlink mode (using GOT) 528 func gentrampdyn(arch *sys.Arch, tramp, target *sym.Symbol, offset int64) { 529 tramp.Size = 20 // 5 instructions 530 o1 := uint32(0xe5900000 | 11<<12 | 15<<16 | 8) // MOVW 8(R15), R11 // R15 is actual pc + 8 531 o2 := uint32(0xe0800000 | 11<<12 | 15<<16 | 11) // ADD R15, R11, R11 532 o3 := uint32(0xe5900000 | 11<<12 | 11<<16) // MOVW (R11), R11 533 o4 := uint32(0xe12fff10 | 11) // JMP (R11) 534 o5 := uint32(0) // WORD $target@GOT // filled in with relocation 535 o6 := uint32(0) 536 if offset != 0 { 537 // insert an instruction to add offset 538 tramp.Size = 24 // 6 instructions 539 o6 = o5 540 o5 = o4 541 o4 = uint32(0xe2800000 | 11<<12 | 11<<16 | immrot(uint32(offset))) // ADD $offset, R11, R11 542 o1 = uint32(0xe5900000 | 11<<12 | 15<<16 | 12) // MOVW 12(R15), R11 543 } 544 tramp.P = make([]byte, tramp.Size) 545 arch.ByteOrder.PutUint32(tramp.P, o1) 546 arch.ByteOrder.PutUint32(tramp.P[4:], o2) 547 arch.ByteOrder.PutUint32(tramp.P[8:], o3) 548 arch.ByteOrder.PutUint32(tramp.P[12:], o4) 549 arch.ByteOrder.PutUint32(tramp.P[16:], o5) 550 if offset != 0 { 551 arch.ByteOrder.PutUint32(tramp.P[20:], o6) 552 } 553 554 r := tramp.AddRel() 555 r.Off = 16 556 r.Type = objabi.R_GOTPCREL 557 r.Siz = 4 558 r.Sym = target 559 r.Add = 8 560 if offset != 0 { 561 // increase reloc offset by 4 as we inserted an ADD instruction 562 r.Off = 20 563 r.Add = 12 564 } 565 } 566 567 func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool { 568 if ctxt.LinkMode == ld.LinkExternal { 569 switch r.Type { 570 case objabi.R_CALLARM: 571 r.Done = false 572 573 // set up addend for eventual relocation via outer symbol. 574 rs := r.Sym 575 576 r.Xadd = int64(signext24(r.Add & 0xffffff)) 577 r.Xadd *= 4 578 for rs.Outer != nil { 579 r.Xadd += ld.Symaddr(rs) - ld.Symaddr(rs.Outer) 580 rs = rs.Outer 581 } 582 583 if rs.Type != sym.SHOSTOBJ && rs.Type != sym.SDYNIMPORT && rs.Sect == nil { 584 ld.Errorf(s, "missing section for %s", rs.Name) 585 } 586 r.Xsym = rs 587 588 // ld64 for arm seems to want the symbol table to contain offset 589 // into the section rather than pseudo virtual address that contains 590 // the section load address. 591 // we need to compensate that by removing the instruction's address 592 // from addend. 593 if ctxt.HeadType == objabi.Hdarwin { 594 r.Xadd -= ld.Symaddr(s) + int64(r.Off) 595 } 596 597 if r.Xadd/4 > 0x7fffff || r.Xadd/4 < -0x800000 { 598 ld.Errorf(s, "direct call too far %d", r.Xadd/4) 599 } 600 601 *val = int64(braddoff(int32(0xff000000&uint32(r.Add)), int32(0xffffff&uint32(r.Xadd/4)))) 602 return true 603 } 604 605 return false 606 } 607 608 switch r.Type { 609 case objabi.R_CONST: 610 *val = r.Add 611 return true 612 case objabi.R_GOTOFF: 613 *val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0)) 614 return true 615 616 // The following three arch specific relocations are only for generation of 617 // Linux/ARM ELF's PLT entry (3 assembler instruction) 618 case objabi.R_PLT0: // add ip, pc, #0xXX00000 619 if ld.Symaddr(ctxt.Syms.Lookup(".got.plt", 0)) < ld.Symaddr(ctxt.Syms.Lookup(".plt", 0)) { 620 ld.Errorf(s, ".got.plt should be placed after .plt section.") 621 } 622 *val = 0xe28fc600 + (0xff & (int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add)) >> 20)) 623 return true 624 case objabi.R_PLT1: // add ip, ip, #0xYY000 625 *val = 0xe28cca00 + (0xff & (int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add+4)) >> 12)) 626 627 return true 628 case objabi.R_PLT2: // ldr pc, [ip, #0xZZZ]! 629 *val = 0xe5bcf000 + (0xfff & int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add+8))) 630 631 return true 632 case objabi.R_CALLARM: // bl XXXXXX or b YYYYYY 633 // r.Add is the instruction 634 // low 24-bit encodes the target address 635 t := (ld.Symaddr(r.Sym) + int64(signext24(r.Add&0xffffff)*4) - (s.Value + int64(r.Off))) / 4 636 if t > 0x7fffff || t < -0x800000 { 637 ld.Errorf(s, "direct call too far: %s %x", r.Sym.Name, t) 638 } 639 *val = int64(braddoff(int32(0xff000000&uint32(r.Add)), int32(0xffffff&t))) 640 641 return true 642 } 643 644 return false 645 } 646 647 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 { 648 log.Fatalf("unexpected relocation variant") 649 return t 650 } 651 652 func addpltreloc(ctxt *ld.Link, plt *sym.Symbol, got *sym.Symbol, s *sym.Symbol, typ objabi.RelocType) *sym.Reloc { 653 r := plt.AddRel() 654 r.Sym = got 655 r.Off = int32(plt.Size) 656 r.Siz = 4 657 r.Type = typ 658 r.Add = int64(s.Got) - 8 659 660 plt.Attr |= sym.AttrReachable 661 plt.Size += 4 662 plt.Grow(plt.Size) 663 664 return r 665 } 666 667 func addpltsym(ctxt *ld.Link, s *sym.Symbol) { 668 if s.Plt >= 0 { 669 return 670 } 671 672 ld.Adddynsym(ctxt, s) 673 674 if ctxt.IsELF { 675 plt := ctxt.Syms.Lookup(".plt", 0) 676 got := ctxt.Syms.Lookup(".got.plt", 0) 677 rel := ctxt.Syms.Lookup(".rel.plt", 0) 678 if plt.Size == 0 { 679 elfsetupplt(ctxt) 680 } 681 682 // .got entry 683 s.Got = int32(got.Size) 684 685 // In theory, all GOT should point to the first PLT entry, 686 // Linux/ARM's dynamic linker will do that for us, but FreeBSD/ARM's 687 // dynamic linker won't, so we'd better do it ourselves. 688 got.AddAddrPlus(ctxt.Arch, plt, 0) 689 690 // .plt entry, this depends on the .got entry 691 s.Plt = int32(plt.Size) 692 693 addpltreloc(ctxt, plt, got, s, objabi.R_PLT0) // add lr, pc, #0xXX00000 694 addpltreloc(ctxt, plt, got, s, objabi.R_PLT1) // add lr, lr, #0xYY000 695 addpltreloc(ctxt, plt, got, s, objabi.R_PLT2) // ldr pc, [lr, #0xZZZ]! 696 697 // rel 698 rel.AddAddrPlus(ctxt.Arch, got, int64(s.Got)) 699 700 rel.AddUint32(ctxt.Arch, ld.ELF32_R_INFO(uint32(s.Dynid), uint32(elf.R_ARM_JUMP_SLOT))) 701 } else { 702 ld.Errorf(s, "addpltsym: unsupported binary format") 703 } 704 } 705 706 func addgotsyminternal(ctxt *ld.Link, s *sym.Symbol) { 707 if s.Got >= 0 { 708 return 709 } 710 711 got := ctxt.Syms.Lookup(".got", 0) 712 s.Got = int32(got.Size) 713 714 got.AddAddrPlus(ctxt.Arch, s, 0) 715 716 if ctxt.IsELF { 717 } else { 718 ld.Errorf(s, "addgotsyminternal: unsupported binary format") 719 } 720 } 721 722 func addgotsym(ctxt *ld.Link, s *sym.Symbol) { 723 if s.Got >= 0 { 724 return 725 } 726 727 ld.Adddynsym(ctxt, s) 728 got := ctxt.Syms.Lookup(".got", 0) 729 s.Got = int32(got.Size) 730 got.AddUint32(ctxt.Arch, 0) 731 732 if ctxt.IsELF { 733 rel := ctxt.Syms.Lookup(".rel", 0) 734 rel.AddAddrPlus(ctxt.Arch, got, int64(s.Got)) 735 rel.AddUint32(ctxt.Arch, ld.ELF32_R_INFO(uint32(s.Dynid), uint32(elf.R_ARM_GLOB_DAT))) 736 } else { 737 ld.Errorf(s, "addgotsym: unsupported binary format") 738 } 739 } 740 741 func asmb(ctxt *ld.Link) { 742 if ctxt.Debugvlog != 0 { 743 ctxt.Logf("%5.2f asmb\n", ld.Cputime()) 744 } 745 746 if ctxt.IsELF { 747 ld.Asmbelfsetup() 748 } 749 750 sect := ld.Segtext.Sections[0] 751 ctxt.Out.SeekSet(int64(sect.Vaddr - ld.Segtext.Vaddr + ld.Segtext.Fileoff)) 752 ld.Codeblk(ctxt, int64(sect.Vaddr), int64(sect.Length)) 753 for _, sect = range ld.Segtext.Sections[1:] { 754 ctxt.Out.SeekSet(int64(sect.Vaddr - ld.Segtext.Vaddr + ld.Segtext.Fileoff)) 755 ld.Datblk(ctxt, int64(sect.Vaddr), int64(sect.Length)) 756 } 757 758 if ld.Segrodata.Filelen > 0 { 759 if ctxt.Debugvlog != 0 { 760 ctxt.Logf("%5.2f rodatblk\n", ld.Cputime()) 761 } 762 ctxt.Out.SeekSet(int64(ld.Segrodata.Fileoff)) 763 ld.Datblk(ctxt, int64(ld.Segrodata.Vaddr), int64(ld.Segrodata.Filelen)) 764 } 765 if ld.Segrelrodata.Filelen > 0 { 766 if ctxt.Debugvlog != 0 { 767 ctxt.Logf("%5.2f relrodatblk\n", ld.Cputime()) 768 } 769 ctxt.Out.SeekSet(int64(ld.Segrelrodata.Fileoff)) 770 ld.Datblk(ctxt, int64(ld.Segrelrodata.Vaddr), int64(ld.Segrelrodata.Filelen)) 771 } 772 773 if ctxt.Debugvlog != 0 { 774 ctxt.Logf("%5.2f datblk\n", ld.Cputime()) 775 } 776 777 ctxt.Out.SeekSet(int64(ld.Segdata.Fileoff)) 778 ld.Datblk(ctxt, int64(ld.Segdata.Vaddr), int64(ld.Segdata.Filelen)) 779 780 ctxt.Out.SeekSet(int64(ld.Segdwarf.Fileoff)) 781 ld.Dwarfblk(ctxt, int64(ld.Segdwarf.Vaddr), int64(ld.Segdwarf.Filelen)) 782 783 machlink := uint32(0) 784 if ctxt.HeadType == objabi.Hdarwin { 785 machlink = uint32(ld.Domacholink(ctxt)) 786 } 787 788 /* output symbol table */ 789 ld.Symsize = 0 790 791 ld.Lcsize = 0 792 symo := uint32(0) 793 if !*ld.FlagS { 794 // TODO: rationalize 795 if ctxt.Debugvlog != 0 { 796 ctxt.Logf("%5.2f sym\n", ld.Cputime()) 797 } 798 switch ctxt.HeadType { 799 default: 800 if ctxt.IsELF { 801 symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen) 802 symo = uint32(ld.Rnd(int64(symo), int64(*ld.FlagRound))) 803 } 804 805 case objabi.Hplan9: 806 symo = uint32(ld.Segdata.Fileoff + ld.Segdata.Filelen) 807 808 case objabi.Hdarwin: 809 symo = uint32(ld.Segdwarf.Fileoff + uint64(ld.Rnd(int64(ld.Segdwarf.Filelen), int64(*ld.FlagRound))) + uint64(machlink)) 810 } 811 812 ctxt.Out.SeekSet(int64(symo)) 813 switch ctxt.HeadType { 814 default: 815 if ctxt.IsELF { 816 if ctxt.Debugvlog != 0 { 817 ctxt.Logf("%5.2f elfsym\n", ld.Cputime()) 818 } 819 ld.Asmelfsym(ctxt) 820 ctxt.Out.Flush() 821 ctxt.Out.Write(ld.Elfstrdat) 822 823 if ctxt.LinkMode == ld.LinkExternal { 824 ld.Elfemitreloc(ctxt) 825 } 826 } 827 828 case objabi.Hplan9: 829 ld.Asmplan9sym(ctxt) 830 ctxt.Out.Flush() 831 832 sym := ctxt.Syms.Lookup("pclntab", 0) 833 if sym != nil { 834 ld.Lcsize = int32(len(sym.P)) 835 ctxt.Out.Write(sym.P) 836 ctxt.Out.Flush() 837 } 838 839 case objabi.Hdarwin: 840 if ctxt.LinkMode == ld.LinkExternal { 841 ld.Machoemitreloc(ctxt) 842 } 843 } 844 } 845 846 if ctxt.Debugvlog != 0 { 847 ctxt.Logf("%5.2f header\n", ld.Cputime()) 848 } 849 ctxt.Out.SeekSet(0) 850 switch ctxt.HeadType { 851 default: 852 case objabi.Hplan9: /* plan 9 */ 853 ctxt.Out.Write32b(0x647) /* magic */ 854 ctxt.Out.Write32b(uint32(ld.Segtext.Filelen)) /* sizes */ 855 ctxt.Out.Write32b(uint32(ld.Segdata.Filelen)) 856 ctxt.Out.Write32b(uint32(ld.Segdata.Length - ld.Segdata.Filelen)) 857 ctxt.Out.Write32b(uint32(ld.Symsize)) /* nsyms */ 858 ctxt.Out.Write32b(uint32(ld.Entryvalue(ctxt))) /* va of entry */ 859 ctxt.Out.Write32b(0) 860 ctxt.Out.Write32b(uint32(ld.Lcsize)) 861 862 case objabi.Hlinux, 863 objabi.Hfreebsd, 864 objabi.Hnetbsd, 865 objabi.Hopenbsd, 866 objabi.Hnacl: 867 ld.Asmbelf(ctxt, int64(symo)) 868 869 case objabi.Hdarwin: 870 ld.Asmbmacho(ctxt) 871 } 872 873 ctxt.Out.Flush() 874 if *ld.FlagC { 875 fmt.Printf("textsize=%d\n", ld.Segtext.Filelen) 876 fmt.Printf("datsize=%d\n", ld.Segdata.Filelen) 877 fmt.Printf("bsssize=%d\n", ld.Segdata.Length-ld.Segdata.Filelen) 878 fmt.Printf("symsize=%d\n", ld.Symsize) 879 fmt.Printf("lcsize=%d\n", ld.Lcsize) 880 fmt.Printf("total=%d\n", ld.Segtext.Filelen+ld.Segdata.Length+uint64(ld.Symsize)+uint64(ld.Lcsize)) 881 } 882 } 883
