main.go

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