bout.c

早期freebsd实现

/* BFD back-end for Intel 960 b.out binaries.
   Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
   Written by Cygnus Support.

This file is part of BFD, the Binary File Descriptor library.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */


#include "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
#include "seclet.h"
#include "bout.h"

#include "aout/stab_gnu.h"
#include "libaout.h"		/* BFD a.out internal data structures */


extern bfd_error_vector_type bfd_error_vector;
PROTO (static boolean, b_out_squirt_out_relocs,(bfd *abfd, asection *section));
PROTO (static bfd_target *, b_out_callback, (bfd *));

PROTO (boolean, aout_32_slurp_symbol_table, (bfd *abfd));
PROTO (void , aout_32_write_syms, ());

/* Swaps the information in an executable header taken from a raw byte
   stream memory image, into the internal exec_header structure.  */

PROTO(void, bout_swap_exec_header_in,
      (bfd *abfd,
      struct external_exec *raw_bytes,
      struct internal_exec *execp));
	 
void
DEFUN(bout_swap_exec_header_in,(abfd, raw_bytes, execp),
      bfd *abfd AND
      struct external_exec *raw_bytes AND
      struct internal_exec *execp)
{
  struct external_exec *bytes = (struct external_exec *)raw_bytes;

  /* Now fill in fields in the execp, from the bytes in the raw data.  */
  execp->a_info   = bfd_h_get_32 (abfd, bytes->e_info);
  execp->a_text   = GET_WORD (abfd, bytes->e_text);
  execp->a_data   = GET_WORD (abfd, bytes->e_data);
  execp->a_bss    = GET_WORD (abfd, bytes->e_bss);
  execp->a_syms   = GET_WORD (abfd, bytes->e_syms);
  execp->a_entry  = GET_WORD (abfd, bytes->e_entry);
  execp->a_trsize = GET_WORD (abfd, bytes->e_trsize);
  execp->a_drsize = GET_WORD (abfd, bytes->e_drsize);
  execp->a_tload  = GET_WORD (abfd, bytes->e_tload);
  execp->a_dload  = GET_WORD (abfd, bytes->e_dload);
  execp->a_talign = bytes->e_talign[0];
  execp->a_dalign = bytes->e_dalign[0];
  execp->a_balign = bytes->e_balign[0];
  execp->a_relaxable = bytes->e_relaxable[0];
}

/* Swaps the information in an internal exec header structure into the
   supplied buffer ready for writing to disk.  */

PROTO(void, bout_swap_exec_header_out,
	  (bfd *abfd,
	   struct internal_exec *execp,
	   struct external_exec *raw_bytes));
void
DEFUN(bout_swap_exec_header_out,(abfd, execp, raw_bytes),
     bfd *abfd AND
     struct internal_exec *execp AND 
     struct external_exec *raw_bytes)
{
  struct external_exec *bytes = (struct external_exec *)raw_bytes;

  /* Now fill in fields in the raw data, from the fields in the exec struct. */
  bfd_h_put_32 (abfd, execp->a_info  , bytes->e_info);
  PUT_WORD (abfd, execp->a_text  , bytes->e_text);
  PUT_WORD (abfd, execp->a_data  , bytes->e_data);
  PUT_WORD (abfd, execp->a_bss   , bytes->e_bss);
  PUT_WORD (abfd, execp->a_syms  , bytes->e_syms);
  PUT_WORD (abfd, execp->a_entry , bytes->e_entry);
  PUT_WORD (abfd, execp->a_trsize, bytes->e_trsize);
  PUT_WORD (abfd, execp->a_drsize, bytes->e_drsize);
  PUT_WORD (abfd, execp->a_tload , bytes->e_tload);
  PUT_WORD (abfd, execp->a_dload , bytes->e_dload);
  bytes->e_talign[0] = execp->a_talign;
  bytes->e_dalign[0] = execp->a_dalign;
  bytes->e_balign[0] = execp->a_balign;
  bytes->e_relaxable[0] = execp->a_relaxable;
}


static bfd_target *
b_out_object_p (abfd)
     bfd *abfd;
{
  struct internal_exec anexec;
  struct external_exec exec_bytes;

  if (bfd_read ((PTR) &exec_bytes, 1, EXEC_BYTES_SIZE, abfd)
      != EXEC_BYTES_SIZE) {
    bfd_error = wrong_format;
    return 0;
  }

  anexec.a_info = bfd_h_get_32 (abfd, exec_bytes.e_info);

  if (N_BADMAG (anexec)) {
    bfd_error = wrong_format;
    return 0;
  }

  bout_swap_exec_header_in (abfd, &exec_bytes, &anexec);
  return aout_32_some_aout_object_p (abfd, &anexec, b_out_callback);
}


/* Finish up the opening of a b.out file for reading.  Fill in all the
   fields that are not handled by common code.  */

static bfd_target *
b_out_callback (abfd)
     bfd *abfd;
{
  struct internal_exec *execp = exec_hdr (abfd);
  unsigned long bss_start;

  /* Architecture and machine type */
  bfd_set_arch_mach(abfd, 
		    bfd_arch_i960, /* B.out only used on i960 */
		    bfd_mach_i960_core /* Default */
		    );

  /* The positions of the string table and symbol table.  */
  obj_str_filepos (abfd) = N_STROFF (*execp);
  obj_sym_filepos (abfd) = N_SYMOFF (*execp);

  /* The alignments of the sections */
  obj_textsec (abfd)->alignment_power = execp->a_talign;
  obj_datasec (abfd)->alignment_power = execp->a_dalign;
  obj_bsssec  (abfd)->alignment_power = execp->a_balign;

  /* The starting addresses of the sections.  */
  obj_textsec (abfd)->vma = execp->a_tload;
  obj_datasec (abfd)->vma = execp->a_dload;

  /* And reload the sizes, since the aout module zaps them */
  obj_textsec (abfd)->_raw_size = execp->a_text;

  bss_start = execp->a_dload + execp->a_data; /* BSS = end of data section */
  obj_bsssec (abfd)->vma = align_power (bss_start, execp->a_balign);

  /* The file positions of the sections */
  obj_textsec (abfd)->filepos = N_TXTOFF(*execp);
  obj_datasec (abfd)->filepos = N_DATOFF(*execp);

  /* The file positions of the relocation info */
  obj_textsec (abfd)->rel_filepos = N_TROFF(*execp);
  obj_datasec (abfd)->rel_filepos =  N_DROFF(*execp);

  adata(abfd).page_size = 1;	/* Not applicable. */
  adata(abfd).segment_size = 1; /* Not applicable. */
  adata(abfd).exec_bytes_size = EXEC_BYTES_SIZE;

  if (execp->a_relaxable)
   abfd->flags |= BFD_IS_RELAXABLE;
  return abfd->xvec;
}

struct bout_data_struct {
    struct aoutdata a;
    struct internal_exec e;
};

static boolean
b_out_mkobject (abfd)
     bfd *abfd;
{
  struct bout_data_struct *rawptr;

  rawptr = (struct bout_data_struct *) bfd_zalloc (abfd, sizeof (struct bout_data_struct));
  if (rawptr == NULL) {
      bfd_error = no_memory;
      return false;
    }

  abfd->tdata.bout_data = rawptr;
  exec_hdr (abfd) = &rawptr->e;

  /* For simplicity's sake we just make all the sections right here. */
  obj_textsec (abfd) = (asection *)NULL;
  obj_datasec (abfd) = (asection *)NULL;
  obj_bsssec (abfd) = (asection *)NULL;

  bfd_make_section (abfd, ".text");
  bfd_make_section (abfd, ".data");
  bfd_make_section (abfd, ".bss");

  return true;
}

static boolean
b_out_write_object_contents (abfd)
     bfd *abfd;
{
  struct external_exec swapped_hdr;

  exec_hdr (abfd)->a_info = BMAGIC;

  exec_hdr (abfd)->a_text = obj_textsec (abfd)->_raw_size;
  exec_hdr (abfd)->a_data = obj_datasec (abfd)->_raw_size;
  exec_hdr (abfd)->a_bss = obj_bsssec (abfd)->_raw_size;
  exec_hdr (abfd)->a_syms = bfd_get_symcount (abfd) * sizeof (struct nlist);
  exec_hdr (abfd)->a_entry = bfd_get_start_address (abfd);
  exec_hdr (abfd)->a_trsize = ((obj_textsec (abfd)->reloc_count) *
                               sizeof (struct relocation_info));
  exec_hdr (abfd)->a_drsize = ((obj_datasec (abfd)->reloc_count) *
                               sizeof (struct relocation_info));

  exec_hdr (abfd)->a_talign = obj_textsec (abfd)->alignment_power;
  exec_hdr (abfd)->a_dalign = obj_datasec (abfd)->alignment_power;
  exec_hdr (abfd)->a_balign = obj_bsssec (abfd)->alignment_power;

  exec_hdr (abfd)->a_tload = obj_textsec (abfd)->vma;
  exec_hdr (abfd)->a_dload = obj_datasec (abfd)->vma;

  bout_swap_exec_header_out (abfd, exec_hdr (abfd), &swapped_hdr);

  bfd_seek (abfd, (file_ptr) 0, SEEK_SET);
  bfd_write ((PTR) &swapped_hdr, 1, EXEC_BYTES_SIZE, abfd);

  /* Now write out reloc info, followed by syms and strings */
  if (bfd_get_symcount (abfd) != 0) 
    {
      bfd_seek (abfd, (file_ptr)(N_SYMOFF(*exec_hdr(abfd))), SEEK_SET);

      aout_32_write_syms (abfd);

      bfd_seek (abfd, (file_ptr)(N_TROFF(*exec_hdr(abfd))), SEEK_SET);

      if (!b_out_squirt_out_relocs (abfd, obj_textsec (abfd))) return false;
      bfd_seek (abfd, (file_ptr)(N_DROFF(*exec_hdr(abfd))), SEEK_SET);

      if (!b_out_squirt_out_relocs (abfd, obj_datasec (abfd))) return false;
    }
  return true;
}

/** Some reloc hackery */

#define CALLS	 0x66003800	/* Template for 'calls' instruction	*/
#define BAL	 0x0b000000	/* Template for 'bal' instruction */
#define BALX	 0x85000000	/* Template for 'balx' instruction	*/
#define BAL_MASK 0x00ffffff
#define CALL     0x09000000
#define PCREL13_MASK 0x1fff
/* Magic to turn callx into calljx */
static bfd_reloc_status_type 
DEFUN (calljx_callback, (abfd, reloc_entry,  src, dst, input_section),
       bfd *abfd AND
       arelent *reloc_entry AND
       PTR src AND
       PTR dst AND

       asection *input_section)
{
  int  word = bfd_get_32(abfd, src);
  asymbol *symbol_in = *(reloc_entry->sym_ptr_ptr);
  aout_symbol_type  *symbol = aout_symbol(symbol_in);

  if (IS_CALLNAME(symbol->other)) 
  {

    aout_symbol_type *balsym = symbol+1;
    int inst = bfd_get_32(abfd, (bfd_byte *) src-4);
    /* The next symbol should be an N_BALNAME */
    BFD_ASSERT(IS_BALNAME(balsym->other));
    inst &= BAL_MASK;
    inst |= BALX;
    bfd_put_32(abfd, inst, (bfd_byte *) dst-4);
    symbol = balsym;
  }

    word += symbol->symbol.section->output_offset +
     symbol->symbol.section->output_section->vma +
      symbol->symbol.value + reloc_entry->addend;

  bfd_put_32(abfd, word, dst);
  return bfd_reloc_ok;
}


/* Magic to turn call into callj */
static bfd_reloc_status_type 
DEFUN (callj_callback, (abfd, reloc_entry,  data, srcidx,dstidx, input_section),
       bfd *abfd AND
       arelent *reloc_entry AND
       PTR data AND
       unsigned int srcidx AND
       unsigned int dstidx AND
       asection *input_section )
{
  int  word = bfd_get_32(abfd, (bfd_byte *) data + srcidx);
  asymbol *symbol_in = *(reloc_entry->sym_ptr_ptr);

  aout_symbol_type  *symbol = aout_symbol(symbol_in);

  if (IS_OTHER(symbol->other)) 
  {
    /* Call to a system procedure - replace code with system
       procedure number */
    word = CALLS | (symbol->other - 1);

  }

  else  if (IS_CALLNAME(symbol->other)) 
  {
    aout_symbol_type *balsym = symbol+1;
    /* The next symbol should be an N_BALNAME */
    BFD_ASSERT(IS_BALNAME(balsym->other));

    /* We are calling a leaf - so replace the call instruction
       with a bal */

    word = BAL |
     (((word & BAL_MASK) +
       balsym->symbol.section->output_offset +
       balsym->symbol.section->output_section->vma+
       balsym->symbol.value + reloc_entry->addend - dstidx -
       ( input_section->output_section->vma + input_section->output_offset))
      & BAL_MASK);


  }
  else 
  {

    word = CALL |
     (((word & BAL_MASK) + 
       symbol->symbol.section->output_offset +
       symbol->symbol.section->output_section->vma+
       symbol->symbol.value + reloc_entry->addend - dstidx -
       ( input_section->output_section->vma + input_section->output_offset))
      & BAL_MASK);
  }
  bfd_put_32(abfd, word, (bfd_byte *) data + dstidx);
  return bfd_reloc_ok;
}

/* type rshift size  bitsize  	pcrel	bitpos  absolute overflow check*/

#define ABS32CODE 0
#define ABS32CODE_SHRUNK 1 
#define PCREL24 2
#define CALLJ 3
#define ABS32 4
#define PCREL13 5
#define ABS32_MAYBE_RELAXABLE 1
#define ABS32_WAS_RELAXABLE 2

#define ALIGNER 10
#define ALIGNDONE 11
static reloc_howto_type howto_reloc_callj =
HOWTO(CALLJ, 0, 2, 24, true, 0, true, true, 0,"callj", true, 0x00ffffff, 0x00ffffff,false);
static  reloc_howto_type howto_reloc_abs32 =
HOWTO(ABS32, 0, 2, 32, false, 0, true, true,0,"abs32", true, 0xffffffff,0xffffffff,false);
static reloc_howto_type howto_reloc_pcrel24 =
HOWTO(PCREL24, 0, 2, 24, true, 0, true, true,0,"pcrel24", true, 0x00ffffff,0x00ffffff,false);

static reloc_howto_type howto_reloc_pcrel13 =
HOWTO(PCREL13, 0, 2, 13, true, 0, true, true,0,"pcrel13", true, 0x00001fff,0x00001fff,false);


static reloc_howto_type howto_reloc_abs32codeshrunk = 
HOWTO(ABS32CODE_SHRUNK, 0, 2, 24, true, 0, true, true, 0,"callx->callj", true, 0x00ffffff, 0x00ffffff,false);

static  reloc_howto_type howto_reloc_abs32code =
HOWTO(ABS32CODE, 0, 2, 32, false, 0, true, true,0,"callx", true, 0xffffffff,0xffffffff,false);

static reloc_howto_type howto_align_table[] = {
  HOWTO (ALIGNER, 0, 0x1, 0, false, 0, false, false, 0, "align16", false, 0, 0, false),
  HOWTO (ALIGNER, 0, 0x3, 0, false, 0, false, false, 0, "align32", false, 0, 0, false),
  HOWTO (ALIGNER, 0, 0x7, 0, false, 0, false, false, 0, "align64", false, 0, 0, false),
  HOWTO (ALIGNER, 0, 0xf, 0, false, 0, false, false, 0, "align128", false, 0, 0, false),
};

static reloc_howto_type howto_done_align_table[] = {
  HOWTO (ALIGNDONE, 0x1, 0x1, 0, false, 0, false, false, 0, "donealign16", false, 0, 0, false),
  HOWTO (ALIGNDONE, 0x3, 0x3, 0, false, 0, false, false, 0, "donealign32", false, 0, 0, false),
  HOWTO (ALIGNDONE, 0x7, 0x7, 0, false, 0, false, false, 0, "donealign64", false, 0, 0, false),
  HOWTO (ALIGNDONE, 0xf, 0xf, 0, false, 0, false, false, 0, "donealign128", false, 0, 0, false),
};

static reloc_howto_type *
b_out_reloc_type_lookup (abfd, code)
     bfd *abfd;
     bfd_reloc_code_real_type code;
{
  switch (code)
    {
    default:
      return 0;
    case BFD_RELOC_I960_CALLJ:
      return &howto_reloc_callj;
    case BFD_RELOC_32:
      return &howto_reloc_abs32;
    case BFD_RELOC_24_PCREL:
      return &howto_reloc_pcrel24;
    }
}

/* Allocate enough room for all the reloc entries, plus pointers to them all */

static boolean
b_out_slurp_reloc_table (abfd, asect, symbols)
     bfd *abfd;
     sec_ptr asect;
     asymbol **symbols;
{
  register struct relocation_info *rptr;
  unsigned int counter ;
  arelent *cache_ptr ;
  int extern_mask, pcrel_mask, callj_mask, length_shift;