1// Inferno utils/6l/obj.c 2// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/obj.c 3// 4// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. 5// Portions Copyright © 1995-1997 C H Forsyth ([email protected]) 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 ([email protected]) 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 31package ld 32 33import ( 34 "bufio" 35 "cmd/internal/goobj" 36 "cmd/internal/objabi" 37 "cmd/internal/quoted" 38 "cmd/internal/sys" 39 "cmd/internal/telemetry/counter" 40 "cmd/link/internal/benchmark" 41 "flag" 42 "internal/buildcfg" 43 "log" 44 "os" 45 "runtime" 46 "runtime/pprof" 47 "strconv" 48 "strings" 49) 50 51var ( 52 pkglistfornote []byte 53 windowsgui bool // writes a "GUI binary" instead of a "console binary" 54 ownTmpDir bool // set to true if tmp dir created by linker (e.g. no -tmpdir) 55) 56 57func init() { 58 flag.Var(&rpath, "r", "set the ELF dynamic linker search `path` to dir1:dir2:...") 59 flag.Var(&flagExtld, "extld", "use `linker` when linking in external mode") 60 flag.Var(&flagExtldflags, "extldflags", "pass `flags` to external linker") 61 flag.Var(&flagW, "w", "disable DWARF generation") 62} 63 64// Flags used by the linker. The exported flags are used by the architecture-specific packages. 65var ( 66 flagBuildid = flag.String("buildid", "", "record `id` as Go toolchain build id") 67 flagBindNow = flag.Bool("bindnow", false, "mark a dynamically linked ELF object for immediate function binding") 68 69 flagOutfile = flag.String("o", "", "write output to `file`") 70 flagPluginPath = flag.String("pluginpath", "", "full path name for plugin") 71 72 flagInstallSuffix = flag.String("installsuffix", "", "set package directory `suffix`") 73 flagDumpDep = flag.Bool("dumpdep", false, "dump symbol dependency graph") 74 flagRace = flag.Bool("race", false, "enable race detector") 75 flagMsan = flag.Bool("msan", false, "enable MSan interface") 76 flagAsan = flag.Bool("asan", false, "enable ASan interface") 77 flagAslr = flag.Bool("aslr", true, "enable ASLR for buildmode=c-shared on windows") 78 79 flagFieldTrack = flag.String("k", "", "set field tracking `symbol`") 80 flagLibGCC = flag.String("libgcc", "", "compiler support lib for internal linking; use \"none\" to disable") 81 flagTmpdir = flag.String("tmpdir", "", "use `directory` for temporary files") 82 83 flagExtld quoted.Flag 84 flagExtldflags quoted.Flag 85 flagExtar = flag.String("extar", "", "archive program for buildmode=c-archive") 86 87 flagCaptureHostObjs = flag.String("capturehostobjs", "", "capture host object files loaded during internal linking to specified dir") 88 89 flagA = flag.Bool("a", false, "no-op (deprecated)") 90 FlagC = flag.Bool("c", false, "dump call graph") 91 FlagD = flag.Bool("d", false, "disable dynamic executable") 92 flagF = flag.Bool("f", false, "ignore version mismatch") 93 flagG = flag.Bool("g", false, "disable go package data checks") 94 flagH = flag.Bool("h", false, "halt on error") 95 flagN = flag.Bool("n", false, "no-op (deprecated)") 96 FlagS = flag.Bool("s", false, "disable symbol table") 97 flag8 bool // use 64-bit addresses in symbol table 98 flagInterpreter = flag.String("I", "", "use `linker` as ELF dynamic linker") 99 flagCheckLinkname = flag.Bool("checklinkname", true, "check linkname symbol references") 100 FlagDebugTramp = flag.Int("debugtramp", 0, "debug trampolines") 101 FlagDebugTextSize = flag.Int("debugtextsize", 0, "debug text section max size") 102 flagDebugNosplit = flag.Bool("debugnosplit", false, "dump nosplit call graph") 103 FlagStrictDups = flag.Int("strictdups", 0, "sanity check duplicate symbol contents during object file reading (1=warn 2=err).") 104 FlagRound = flag.Int64("R", -1, "set address rounding `quantum`") 105 FlagTextAddr = flag.Int64("T", -1, "set the start address of text symbols") 106 flagEntrySymbol = flag.String("E", "", "set `entry` symbol name") 107 flagPruneWeakMap = flag.Bool("pruneweakmap", true, "prune weak mapinit refs") 108 flagRandLayout = flag.Int64("randlayout", 0, "randomize function layout") 109 cpuprofile = flag.String("cpuprofile", "", "write cpu profile to `file`") 110 memprofile = flag.String("memprofile", "", "write memory profile to `file`") 111 memprofilerate = flag.Int64("memprofilerate", 0, "set runtime.MemProfileRate to `rate`") 112 benchmarkFlag = flag.String("benchmark", "", "set to 'mem' or 'cpu' to enable phase benchmarking") 113 benchmarkFileFlag = flag.String("benchmarkprofile", "", "emit phase profiles to `base`_phase.{cpu,mem}prof") 114 115 flagW ternaryFlag 116 FlagW = new(bool) // the -w flag, computed in main from flagW 117) 118 119// ternaryFlag is like a boolean flag, but has a default value that is 120// neither true nor false, allowing it to be set from context (e.g. from another 121// flag). 122// *ternaryFlag implements flag.Value. 123type ternaryFlag int 124 125const ( 126 ternaryFlagUnset ternaryFlag = iota 127 ternaryFlagFalse 128 ternaryFlagTrue 129) 130 131func (t *ternaryFlag) Set(s string) error { 132 v, err := strconv.ParseBool(s) 133 if err != nil { 134 return err 135 } 136 if v { 137 *t = ternaryFlagTrue 138 } else { 139 *t = ternaryFlagFalse 140 } 141 return nil 142} 143 144func (t *ternaryFlag) String() string { 145 switch *t { 146 case ternaryFlagFalse: 147 return "false" 148 case ternaryFlagTrue: 149 return "true" 150 } 151 return "unset" 152} 153 154func (t *ternaryFlag) IsBoolFlag() bool { return true } // parse like a boolean flag 155 156// Main is the main entry point for the linker code. 157func Main(arch *sys.Arch, theArch Arch) { 158 log.SetPrefix("link: ") 159 log.SetFlags(0) 160 counter.Open() 161 counter.Inc("link/invocations") 162 163 thearch = theArch 164 ctxt := linknew(arch) 165 ctxt.Bso = bufio.NewWriter(os.Stdout) 166 167 // For testing behavior of go command when tools crash silently. 168 // Undocumented, not in standard flag parser to avoid 169 // exposing in usage message. 170 for _, arg := range os.Args { 171 if arg == "-crash_for_testing" { 172 os.Exit(2) 173 } 174 } 175 176 if buildcfg.GOROOT == "" { 177 // cmd/go clears the GOROOT variable when -trimpath is set, 178 // so omit it from the binary even if cmd/link itself has an 179 // embedded GOROOT value reported by runtime.GOROOT. 180 } else { 181 addstrdata1(ctxt, "runtime.defaultGOROOT="+buildcfg.GOROOT) 182 } 183 184 buildVersion := buildcfg.Version 185 if goexperiment := buildcfg.Experiment.String(); goexperiment != "" { 186 buildVersion += " X:" + goexperiment 187 } 188 addstrdata1(ctxt, "runtime.buildVersion="+buildVersion) 189 190 // TODO(matloob): define these above and then check flag values here 191 if ctxt.Arch.Family == sys.AMD64 && buildcfg.GOOS == "plan9" { 192 flag.BoolVar(&flag8, "8", false, "use 64-bit addresses in symbol table") 193 } 194 flagHeadType := flag.String("H", "", "set header `type`") 195 flag.BoolVar(&ctxt.linkShared, "linkshared", false, "link against installed Go shared libraries") 196 flag.Var(&ctxt.LinkMode, "linkmode", "set link `mode`") 197 flag.Var(&ctxt.BuildMode, "buildmode", "set build `mode`") 198 flag.BoolVar(&ctxt.compressDWARF, "compressdwarf", true, "compress DWARF if possible") 199 objabi.Flagfn1("B", "add an ELF NT_GNU_BUILD_ID `note` when using ELF; use \"gobuildid\" to generate it from the Go build ID", addbuildinfo) 200 objabi.Flagfn1("L", "add specified `directory` to library path", func(a string) { Lflag(ctxt, a) }) 201 objabi.AddVersionFlag() // -V 202 objabi.Flagfn1("X", "add string value `definition` of the form importpath.name=value", func(s string) { addstrdata1(ctxt, s) }) 203 objabi.Flagcount("v", "print link trace", &ctxt.Debugvlog) 204 objabi.Flagfn1("importcfg", "read import configuration from `file`", ctxt.readImportCfg) 205 206 objabi.Flagparse(usage) 207 counter.CountFlags("link/flag:", *flag.CommandLine) 208 209 if ctxt.Debugvlog > 0 { 210 // dump symbol info on crash 211 defer func() { ctxt.loader.Dump() }() 212 } 213 if ctxt.Debugvlog > 1 { 214 // dump symbol info on error 215 AtExit(func() { 216 if nerrors > 0 { 217 ctxt.loader.Dump() 218 } 219 }) 220 } 221 222 switch *flagHeadType { 223 case "": 224 case "windowsgui": 225 ctxt.HeadType = objabi.Hwindows 226 windowsgui = true 227 default: 228 if err := ctxt.HeadType.Set(*flagHeadType); err != nil { 229 Errorf(nil, "%v", err) 230 usage() 231 } 232 } 233 if ctxt.HeadType == objabi.Hunknown { 234 ctxt.HeadType.Set(buildcfg.GOOS) 235 } 236 237 if !*flagAslr && ctxt.BuildMode != BuildModeCShared { 238 Errorf(nil, "-aslr=false is only allowed for -buildmode=c-shared") 239 usage() 240 } 241 242 if *FlagD && ctxt.UsesLibc() { 243 Exitf("dynamic linking required on %s; -d flag cannot be used", buildcfg.GOOS) 244 } 245 246 isPowerOfTwo := func(n int64) bool { 247 return n > 0 && n&(n-1) == 0 248 } 249 if *FlagRound != -1 && (*FlagRound < 4096 || !isPowerOfTwo(*FlagRound)) { 250 Exitf("invalid -R value 0x%x", *FlagRound) 251 } 252 253 checkStrictDups = *FlagStrictDups 254 255 switch flagW { 256 case ternaryFlagFalse: 257 *FlagW = false 258 case ternaryFlagTrue: 259 *FlagW = true 260 case ternaryFlagUnset: 261 *FlagW = *FlagS // -s implies -w if not explicitly set 262 if ctxt.IsDarwin() && ctxt.BuildMode == BuildModeCShared { 263 *FlagW = true // default to -w in c-shared mode on darwin, see #61229 264 } 265 } 266 267 if !buildcfg.Experiment.RegabiWrappers { 268 abiInternalVer = 0 269 } 270 271 startProfile() 272 if ctxt.BuildMode == BuildModeUnset { 273 ctxt.BuildMode.Set("exe") 274 } 275 276 if ctxt.BuildMode != BuildModeShared && flag.NArg() != 1 { 277 usage() 278 } 279 280 if *flagOutfile == "" { 281 *flagOutfile = "a.out" 282 if ctxt.HeadType == objabi.Hwindows { 283 *flagOutfile += ".exe" 284 } 285 } 286 287 interpreter = *flagInterpreter 288 289 if *flagBuildid == "" && ctxt.Target.IsOpenbsd() { 290 // TODO(jsing): Remove once direct syscalls are no longer in use. 291 // OpenBSD 6.7 onwards will not permit direct syscalls from a 292 // dynamically linked binary unless it identifies the binary 293 // contains a .note.go.buildid ELF note. See issue #36435. 294 *flagBuildid = "go-openbsd" 295 } 296 297 // enable benchmarking 298 var bench *benchmark.Metrics 299 if len(*benchmarkFlag) != 0 { 300 if *benchmarkFlag == "mem" { 301 bench = benchmark.New(benchmark.GC, *benchmarkFileFlag) 302 } else if *benchmarkFlag == "cpu" { 303 bench = benchmark.New(benchmark.NoGC, *benchmarkFileFlag) 304 } else { 305 Errorf(nil, "unknown benchmark flag: %q", *benchmarkFlag) 306 usage() 307 } 308 } 309 310 bench.Start("libinit") 311 libinit(ctxt) // creates outfile 312 bench.Start("computeTLSOffset") 313 ctxt.computeTLSOffset() 314 bench.Start("Archinit") 315 thearch.Archinit(ctxt) 316 317 if ctxt.linkShared && !ctxt.IsELF { 318 Exitf("-linkshared can only be used on elf systems") 319 } 320 321 if ctxt.Debugvlog != 0 { 322 onOff := func(b bool) string { 323 if b { 324 return "on" 325 } 326 return "off" 327 } 328 ctxt.Logf("build mode: %s, symbol table: %s, DWARF: %s\n", ctxt.BuildMode, onOff(!*FlagS), onOff(dwarfEnabled(ctxt))) 329 ctxt.Logf("HEADER = -H%d -T0x%x -R0x%x\n", ctxt.HeadType, uint64(*FlagTextAddr), uint32(*FlagRound)) 330 } 331 332 zerofp := goobj.FingerprintType{} 333 switch ctxt.BuildMode { 334 case BuildModeShared: 335 for i := 0; i < flag.NArg(); i++ { 336 arg := flag.Arg(i) 337 parts := strings.SplitN(arg, "=", 2) 338 var pkgpath, file string 339 if len(parts) == 1 { 340 pkgpath, file = "main", arg 341 } else { 342 pkgpath, file = parts[0], parts[1] 343 } 344 pkglistfornote = append(pkglistfornote, pkgpath...) 345 pkglistfornote = append(pkglistfornote, '\n') 346 addlibpath(ctxt, "command line", "command line", file, pkgpath, "", zerofp) 347 } 348 case BuildModePlugin: 349 addlibpath(ctxt, "command line", "command line", flag.Arg(0), *flagPluginPath, "", zerofp) 350 default: 351 addlibpath(ctxt, "command line", "command line", flag.Arg(0), "main", "", zerofp) 352 } 353 bench.Start("loadlib") 354 ctxt.loadlib() 355 356 bench.Start("inittasks") 357 ctxt.inittasks() 358 359 bench.Start("deadcode") 360 deadcode(ctxt) 361 362 bench.Start("linksetup") 363 ctxt.linksetup() 364 365 bench.Start("dostrdata") 366 ctxt.dostrdata() 367 if buildcfg.Experiment.FieldTrack { 368 bench.Start("fieldtrack") 369 fieldtrack(ctxt.Arch, ctxt.loader) 370 } 371 372 bench.Start("dwarfGenerateDebugInfo") 373 dwarfGenerateDebugInfo(ctxt) 374 375 bench.Start("callgraph") 376 ctxt.callgraph() 377 378 bench.Start("doStackCheck") 379 ctxt.doStackCheck() 380 381 bench.Start("mangleTypeSym") 382 ctxt.mangleTypeSym() 383 384 if ctxt.IsELF { 385 bench.Start("doelf") 386 ctxt.doelf() 387 } 388 if ctxt.IsDarwin() { 389 bench.Start("domacho") 390 ctxt.domacho() 391 } 392 if ctxt.IsWindows() { 393 bench.Start("dope") 394 ctxt.dope() 395 bench.Start("windynrelocsyms") 396 ctxt.windynrelocsyms() 397 } 398 if ctxt.IsAIX() { 399 bench.Start("doxcoff") 400 ctxt.doxcoff() 401 } 402 403 bench.Start("textbuildid") 404 ctxt.textbuildid() 405 bench.Start("addexport") 406 ctxt.setArchSyms() 407 ctxt.addexport() 408 bench.Start("Gentext") 409 thearch.Gentext(ctxt, ctxt.loader) // trampolines, call stubs, etc. 410 411 bench.Start("textaddress") 412 ctxt.textaddress() 413 bench.Start("typelink") 414 ctxt.typelink() 415 bench.Start("buildinfo") 416 ctxt.buildinfo() 417 bench.Start("pclntab") 418 containers := ctxt.findContainerSyms() 419 pclnState := ctxt.pclntab(containers) 420 bench.Start("findfunctab") 421 ctxt.findfunctab(pclnState, containers) 422 bench.Start("dwarfGenerateDebugSyms") 423 dwarfGenerateDebugSyms(ctxt) 424 bench.Start("symtab") 425 symGroupType := ctxt.symtab(pclnState) 426 bench.Start("dodata") 427 ctxt.dodata(symGroupType) 428 bench.Start("address") 429 order := ctxt.address() 430 bench.Start("dwarfcompress") 431 dwarfcompress(ctxt) 432 bench.Start("layout") 433 filesize := ctxt.layout(order) 434 435 // Write out the output file. 436 // It is split into two parts (Asmb and Asmb2). The first 437 // part writes most of the content (sections and segments), 438 // for which we have computed the size and offset, in a 439 // mmap'd region. The second part writes more content, for 440 // which we don't know the size. 441 if ctxt.Arch.Family != sys.Wasm { 442 // Don't mmap if we're building for Wasm. Wasm file 443 // layout is very different so filesize is meaningless. 444 if err := ctxt.Out.Mmap(filesize); err != nil { 445 Exitf("mapping output file failed: %v", err) 446 } 447 } 448 // asmb will redirect symbols to the output file mmap, and relocations 449 // will be applied directly there. 450 bench.Start("Asmb") 451 asmb(ctxt) 452 453 exitIfErrors() 454 455 // Generate additional symbols for the native symbol table just prior 456 // to code generation. 457 bench.Start("GenSymsLate") 458 if thearch.GenSymsLate != nil { 459 thearch.GenSymsLate(ctxt, ctxt.loader) 460 } 461 462 bench.Start("Asmb2") 463 asmb2(ctxt) 464 465 bench.Start("Munmap") 466 ctxt.Out.Close() // Close handles Munmapping if necessary. 467 468 bench.Start("hostlink") 469 ctxt.hostlink() 470 if ctxt.Debugvlog != 0 { 471 ctxt.Logf("%s", ctxt.loader.Stat()) 472 ctxt.Logf("%d liveness data\n", liveness) 473 } 474 bench.Start("Flush") 475 ctxt.Bso.Flush() 476 bench.Start("archive") 477 ctxt.archive() 478 bench.Report(os.Stdout) 479 480 errorexit() 481} 482 483type Rpath struct { 484 set bool 485 val string 486} 487 488func (r *Rpath) Set(val string) error { 489 r.set = true 490 r.val = val 491 return nil 492} 493 494func (r *Rpath) String() string { 495 return r.val 496} 497 498func startProfile() { 499 if *cpuprofile != "" { 500 f, err := os.Create(*cpuprofile) 501 if err != nil { 502 log.Fatalf("%v", err) 503 } 504 if err := pprof.StartCPUProfile(f); err != nil { 505 log.Fatalf("%v", err) 506 } 507 AtExit(func() { 508 pprof.StopCPUProfile() 509 if err = f.Close(); err != nil { 510 log.Fatalf("error closing cpu profile: %v", err) 511 } 512 }) 513 } 514 if *memprofile != "" { 515 if *memprofilerate != 0 { 516 runtime.MemProfileRate = int(*memprofilerate) 517 } 518 f, err := os.Create(*memprofile) 519 if err != nil { 520 log.Fatalf("%v", err) 521 } 522 AtExit(func() { 523 // Profile all outstanding allocations. 524 runtime.GC() 525 // compilebench parses the memory profile to extract memstats, 526 // which are only written in the legacy pprof format. 527 // See golang.org/issue/18641 and runtime/pprof/pprof.go:writeHeap. 528 const writeLegacyFormat = 1 529 if err := pprof.Lookup("heap").WriteTo(f, writeLegacyFormat); err != nil { 530 log.Fatalf("%v", err) 531 } 532 // Close the file after writing the profile. 533 if err := f.Close(); err != nil { 534 log.Fatalf("could not close %v: %v", *memprofile, err) 535 } 536 }) 537 } 538} 539