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Source file src/cmd/link/internal/ld/sym.go

Documentation: cmd/link/internal/ld

     1  // Derived from Inferno utils/6l/obj.c and utils/6l/span.c
     2  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/obj.c
     3  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/span.c
     4  //
     5  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
     6  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
     7  //	Portions Copyright © 1997-1999 Vita Nuova Limited
     8  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
     9  //	Portions Copyright © 2004,2006 Bruce Ellis
    10  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
    11  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
    12  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
    13  //
    14  // Permission is hereby granted, free of charge, to any person obtaining a copy
    15  // of this software and associated documentation files (the "Software"), to deal
    16  // in the Software without restriction, including without limitation the rights
    17  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    18  // copies of the Software, and to permit persons to whom the Software is
    19  // furnished to do so, subject to the following conditions:
    20  //
    21  // The above copyright notice and this permission notice shall be included in
    22  // all copies or substantial portions of the Software.
    23  //
    24  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    25  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    26  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    27  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    28  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    29  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    30  // THE SOFTWARE.
    31  
    32  package ld
    33  
    34  import (
    35  	"cmd/internal/objabi"
    36  	"cmd/internal/sys"
    37  	"cmd/link/internal/loader"
    38  	"cmd/link/internal/sym"
    39  	"log"
    40  	"runtime"
    41  )
    42  
    43  func linknew(arch *sys.Arch) *Link {
    44  	ler := loader.ErrorReporter{AfterErrorAction: afterErrorAction}
    45  	ctxt := &Link{
    46  		Target:        Target{Arch: arch},
    47  		version:       sym.SymVerStatic,
    48  		outSem:        make(chan int, 2*runtime.GOMAXPROCS(0)),
    49  		Out:           NewOutBuf(arch),
    50  		LibraryByPkg:  make(map[string]*sym.Library),
    51  		numelfsym:     1,
    52  		ErrorReporter: ErrorReporter{ErrorReporter: ler},
    53  		generatorSyms: make(map[loader.Sym]generatorFunc),
    54  	}
    55  
    56  	if objabi.GOARCH != arch.Name {
    57  		log.Fatalf("invalid objabi.GOARCH %s (want %s)", objabi.GOARCH, arch.Name)
    58  	}
    59  
    60  	AtExit(func() {
    61  		if nerrors > 0 {
    62  			ctxt.Out.Close()
    63  			mayberemoveoutfile()
    64  		}
    65  	})
    66  
    67  	return ctxt
    68  }
    69  
    70  // computeTLSOffset records the thread-local storage offset.
    71  // Not used for Android where the TLS offset is determined at runtime.
    72  func (ctxt *Link) computeTLSOffset() {
    73  	switch ctxt.HeadType {
    74  	default:
    75  		log.Fatalf("unknown thread-local storage offset for %v", ctxt.HeadType)
    76  
    77  	case objabi.Hplan9, objabi.Hwindows, objabi.Hjs, objabi.Haix:
    78  		break
    79  
    80  	case objabi.Hlinux,
    81  		objabi.Hfreebsd,
    82  		objabi.Hnetbsd,
    83  		objabi.Hopenbsd,
    84  		objabi.Hdragonfly,
    85  		objabi.Hsolaris:
    86  		/*
    87  		 * ELF uses TLS offset negative from FS.
    88  		 * Translate 0(FS) and 8(FS) into -16(FS) and -8(FS).
    89  		 * Known to low-level assembly in package runtime and runtime/cgo.
    90  		 */
    91  		ctxt.Tlsoffset = -1 * ctxt.Arch.PtrSize
    92  
    93  	case objabi.Hdarwin:
    94  		/*
    95  		 * OS X system constants - offset from 0(GS) to our TLS.
    96  		 */
    97  		switch ctxt.Arch.Family {
    98  		default:
    99  			log.Fatalf("unknown thread-local storage offset for darwin/%s", ctxt.Arch.Name)
   100  
   101  			/*
   102  			 * For x86, Apple has reserved a slot in the TLS for Go. See issue 23617.
   103  			 * That slot is at offset 0x30 on amd64.
   104  			 * The slot will hold the G pointer.
   105  			 * These constants should match those in runtime/sys_darwin_amd64.s
   106  			 * and runtime/cgo/gcc_darwin_amd64.c.
   107  			 */
   108  		case sys.AMD64:
   109  			ctxt.Tlsoffset = 0x30
   110  
   111  		case sys.ARM64:
   112  			ctxt.Tlsoffset = 0 // dummy value, not needed
   113  		}
   114  	}
   115  
   116  }
   117  

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