data.go

     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 obj
    33  
    34  import (
    35  	"cmd/internal/objabi"
    36  	"log"
    37  	"math"
    38  )
    39  
    40  // Grow increases the length of s.P to lsiz.
    41  func (s *LSym) Grow(lsiz int64) {
    42  	siz := int(lsiz)
    43  	if int64(siz) != lsiz {
    44  		log.Fatalf("LSym.Grow size %d too long", lsiz)
    45  	}
    46  	if len(s.P) >= siz {
    47  		return
    48  	}
    49  	s.P = append(s.P, make([]byte, siz-len(s.P))...)
    50  }
    51  
    52  // GrowCap increases the capacity of s.P to c.
    53  func (s *LSym) GrowCap(c int64) {
    54  	if int64(cap(s.P)) >= c {
    55  		return
    56  	}
    57  	if s.P == nil {
    58  		s.P = make([]byte, 0, c)
    59  		return
    60  	}
    61  	b := make([]byte, len(s.P), c)
    62  	copy(b, s.P)
    63  	s.P = b
    64  }
    65  
    66  // prepwrite prepares to write data of size siz into s at offset off.
    67  func (s *LSym) prepwrite(ctxt *Link, off int64, siz int) {
    68  	if off < 0 || siz < 0 || off >= 1<<30 {
    69  		ctxt.Diag("prepwrite: bad off=%d siz=%d s=%v", off, siz, s)
    70  	}
    71  	switch s.Type {
    72  	case objabi.Sxxx, objabi.SBSS:
    73  		s.Type = objabi.SDATA
    74  	case objabi.SNOPTRBSS:
    75  		s.Type = objabi.SNOPTRDATA
    76  	case objabi.STLSBSS:
    77  		ctxt.Diag("cannot supply data for %v var %v", s.Type, s.Name)
    78  	}
    79  	s.setFIPSType(ctxt)
    80  	l := off + int64(siz)
    81  	s.Grow(l)
    82  	if l > s.Size {
    83  		s.Size = l
    84  	}
    85  }
    86  
    87  // WriteFloat32 writes f into s at offset off.
    88  func (s *LSym) WriteFloat32(ctxt *Link, off int64, f float32) {
    89  	s.prepwrite(ctxt, off, 4)
    90  	ctxt.Arch.ByteOrder.PutUint32(s.P[off:], math.Float32bits(f))
    91  }
    92  
    93  // WriteFloat64 writes f into s at offset off.
    94  func (s *LSym) WriteFloat64(ctxt *Link, off int64, f float64) {
    95  	s.prepwrite(ctxt, off, 8)
    96  	ctxt.Arch.ByteOrder.PutUint64(s.P[off:], math.Float64bits(f))
    97  }
    98  
    99  // WriteInt writes an integer i of size siz into s at offset off.
   100  func (s *LSym) WriteInt(ctxt *Link, off int64, siz int, i int64) {
   101  	s.prepwrite(ctxt, off, siz)
   102  	switch siz {
   103  	default:
   104  		ctxt.Diag("WriteInt: bad integer size: %d", siz)
   105  	case 1:
   106  		s.P[off] = byte(i)
   107  	case 2:
   108  		ctxt.Arch.ByteOrder.PutUint16(s.P[off:], uint16(i))
   109  	case 4:
   110  		ctxt.Arch.ByteOrder.PutUint32(s.P[off:], uint32(i))
   111  	case 8:
   112  		ctxt.Arch.ByteOrder.PutUint64(s.P[off:], uint64(i))
   113  	}
   114  }
   115  
   116  func (s *LSym) writeAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64, rtype objabi.RelocType) {
   117  	// Allow 4-byte addresses for DWARF.
   118  	if siz != ctxt.Arch.PtrSize && siz != 4 {
   119  		ctxt.Diag("WriteAddr: bad address size %d in %s", siz, s.Name)
   120  	}
   121  	s.prepwrite(ctxt, off, siz)
   122  	if int64(int32(off)) != off {
   123  		ctxt.Diag("WriteAddr: off overflow %d in %s", off, s.Name)
   124  	}
   125  	s.AddRel(ctxt, Reloc{
   126  		Type: rtype,
   127  		Off:  int32(off),
   128  		Siz:  uint8(siz),
   129  		Sym:  rsym,
   130  		Add:  roff,
   131  	})
   132  }
   133  
   134  // WriteAddr writes an address of size siz into s at offset off.
   135  // rsym and roff specify the relocation for the address.
   136  func (s *LSym) WriteAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64) {
   137  	s.writeAddr(ctxt, off, siz, rsym, roff, objabi.R_ADDR)
   138  }
   139  
   140  // WriteWeakAddr writes an address of size siz into s at offset off.
   141  // rsym and roff specify the relocation for the address.
   142  // This is a weak reference.
   143  func (s *LSym) WriteWeakAddr(ctxt *Link, off int64, siz int, rsym *LSym, roff int64) {
   144  	s.writeAddr(ctxt, off, siz, rsym, roff, objabi.R_WEAKADDR)
   145  }
   146  
   147  // WriteCURelativeAddr writes a pointer-sized address into s at offset off.
   148  // rsym and roff specify the relocation for the address which will be
   149  // resolved by the linker to an offset from the DW_AT_low_pc attribute of
   150  // the DWARF Compile Unit of rsym.
   151  func (s *LSym) WriteCURelativeAddr(ctxt *Link, off int64, rsym *LSym, roff int64) {
   152  	s.writeAddr(ctxt, off, ctxt.Arch.PtrSize, rsym, roff, objabi.R_ADDRCUOFF)
   153  }
   154  
   155  // WriteOff writes a 4 byte offset to rsym+roff into s at offset off.
   156  // After linking the 4 bytes stored at s+off will be
   157  // rsym+roff-(start of section that s is in).
   158  func (s *LSym) WriteOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
   159  	s.prepwrite(ctxt, off, 4)
   160  	if int64(int32(off)) != off {
   161  		ctxt.Diag("WriteOff: off overflow %d in %s", off, s.Name)
   162  	}
   163  	s.AddRel(ctxt, Reloc{
   164  		Type: objabi.R_ADDROFF,
   165  		Off:  int32(off),
   166  		Siz:  4,
   167  		Sym:  rsym,
   168  		Add:  roff,
   169  	})
   170  }
   171  
   172  // WriteWeakOff writes a weak 4 byte offset to rsym+roff into s at offset off.
   173  // After linking the 4 bytes stored at s+off will be
   174  // rsym+roff-(start of section that s is in).
   175  func (s *LSym) WriteWeakOff(ctxt *Link, off int64, rsym *LSym, roff int64) {
   176  	s.prepwrite(ctxt, off, 4)
   177  	if int64(int32(off)) != off {
   178  		ctxt.Diag("WriteWeakOff: off overflow %d in %s", off, s.Name)
   179  	}
   180  	s.AddRel(ctxt, Reloc{
   181  		Type: objabi.R_WEAKADDROFF,
   182  		Off:  int32(off),
   183  		Siz:  4,
   184  		Sym:  rsym,
   185  		Add:  roff,
   186  	})
   187  }
   188  
   189  // WriteString writes a string of size siz into s at offset off.
   190  func (s *LSym) WriteString(ctxt *Link, off int64, siz int, str string) {
   191  	if siz < len(str) {
   192  		ctxt.Diag("WriteString: bad string size: %d < %d", siz, len(str))
   193  	}
   194  	s.prepwrite(ctxt, off, siz)
   195  	copy(s.P[off:off+int64(siz)], str)
   196  }
   197  
   198  // WriteBytes writes a slice of bytes into s at offset off.
   199  func (s *LSym) WriteBytes(ctxt *Link, off int64, b []byte) int64 {
   200  	s.prepwrite(ctxt, off, len(b))
   201  	copy(s.P[off:], b)
   202  	return off + int64(len(b))
   203  }
   204  
   205  // AddRel adds the relocation rel to s.
   206  func (s *LSym) AddRel(ctxt *Link, rel Reloc) {
   207  	if s.Type.IsFIPS() {
   208  		s.checkFIPSReloc(ctxt, rel)
   209  	}
   210  	s.R = append(s.R, rel)
   211  }
   212  
   213  // WriteDwTxtAddrx appends a zero blob of the proper size to s at off
   214  // and attaches one of the various R_DWTXTADDR_U* relocations to the
   215  // symbol. Here size is dependent on the total number of functions in
   216  // the package (for more on why this is needed, consult the
   217  // .debug_addr generation code in the linker).
   218  func (s *LSym) WriteDwTxtAddrx(ctxt *Link, off int64, rsym *LSym, maxFuncs int) {
   219  	rtype, sz := objabi.FuncCountToDwTxtAddrFlavor(maxFuncs)
   220  	s.prepwrite(ctxt, off, sz)
   221  	if int64(int32(off)) != off {
   222  		ctxt.Diag("WriteDwTxtAddrx: off overflow %d in %s", off, s.Name)
   223  	}
   224  	s.AddRel(ctxt, Reloc{
   225  		Type: rtype,
   226  		Off:  int32(off),
   227  		Siz:  uint8(sz),
   228  		Sym:  rsym,
   229  	})
   230  }
   231
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