obj-elf.c

基于4个mips核的noc设计

static void
adjust_stab_sections (abfd, sec, xxx)
     bfd *abfd;
     asection *sec;
     PTR xxx ATTRIBUTE_UNUSED;
{
  char *name;
  asection *strsec;
  char *p;
  int strsz, nsyms;

  if (strncmp (".stab", sec->name, 5))
    return;
  if (!strcmp ("str", sec->name + strlen (sec->name) - 3))
    return;

  name = (char *) alloca (strlen (sec->name) + 4);
  strcpy (name, sec->name);
  strcat (name, "str");
  strsec = bfd_get_section_by_name (abfd, name);
  if (strsec)
    strsz = bfd_section_size (abfd, strsec);
  else
    strsz = 0;
  nsyms = bfd_section_size (abfd, sec) / 12 - 1;

  p = seg_info (sec)->stabu.p;
  assert (p != 0);

  bfd_h_put_16 (abfd, (bfd_vma) nsyms, (bfd_byte *) p + 6);
  bfd_h_put_32 (abfd, (bfd_vma) strsz, (bfd_byte *) p + 8);
}

#ifdef NEED_ECOFF_DEBUG

/* This function is called by the ECOFF code.  It is supposed to
   record the external symbol information so that the backend can
   write it out correctly.  The ELF backend doesn't actually handle
   this at the moment, so we do it ourselves.  We save the information
   in the symbol.  */

void
elf_ecoff_set_ext (sym, ext)
     symbolS *sym;
     struct ecoff_extr *ext;
{
  symbol_get_bfdsym (sym)->udata.p = (PTR) ext;
}

/* This function is called by bfd_ecoff_debug_externals.  It is
   supposed to *EXT to the external symbol information, and return
   whether the symbol should be used at all.  */

static boolean
elf_get_extr (sym, ext)
     asymbol *sym;
     EXTR *ext;
{
  if (sym->udata.p == NULL)
    return false;
  *ext = *(EXTR *) sym->udata.p;
  return true;
}

/* This function is called by bfd_ecoff_debug_externals.  It has
   nothing to do for ELF.  */

/*ARGSUSED*/
static void
elf_set_index (sym, indx)
     asymbol *sym ATTRIBUTE_UNUSED;
     bfd_size_type indx ATTRIBUTE_UNUSED;
{
}

#endif /* NEED_ECOFF_DEBUG */

void
elf_frob_symbol (symp, puntp)
     symbolS *symp;
     int *puntp;
{
  struct elf_obj_sy *sy_obj;

#ifdef NEED_ECOFF_DEBUG
  if (ECOFF_DEBUGGING)
    ecoff_frob_symbol (symp);
#endif

  sy_obj = symbol_get_obj (symp);

  if (sy_obj->size != NULL)
    {
      switch (sy_obj->size->X_op)
	{
	case O_subtract:
	  S_SET_SIZE (symp,
		      (S_GET_VALUE (sy_obj->size->X_add_symbol)
		       + sy_obj->size->X_add_number
		       - S_GET_VALUE (sy_obj->size->X_op_symbol)));
	  break;
	case O_constant:
	  S_SET_SIZE (symp,
		      (S_GET_VALUE (sy_obj->size->X_add_symbol)
		       + sy_obj->size->X_add_number));
	  break;
	default:
	  as_bad (_(".size expression too complicated to fix up"));
	  break;
	}
      free (sy_obj->size);
      sy_obj->size = NULL;
    }

  if (sy_obj->versioned_name != NULL)
    {
      char *p;

      p = strchr (sy_obj->versioned_name, ELF_VER_CHR);
      know (p != NULL);

      /* This symbol was given a new name with the .symver directive.

         If this is an external reference, just rename the symbol to
         include the version string.  This will make the relocs be
         against the correct versioned symbol.

	 If this is a definition, add an alias.  FIXME: Using an alias
	 will permit the debugging information to refer to the right
	 symbol.  However, it's not clear whether it is the best
	 approach.  */

      if (! S_IS_DEFINED (symp))
	{
	  /* Verify that the name isn't using the @@ syntax--this is
             reserved for definitions of the default version to link
             against.  */
	  if (p[1] == ELF_VER_CHR)
	    {
	      as_bad (_("invalid attempt to declare external version name as default in symbol `%s'"),
		      sy_obj->versioned_name);
	      *puntp = true;
	    }
	  S_SET_NAME (symp, sy_obj->versioned_name);
	}
      else
	{
	  if (p [1] == ELF_VER_CHR && p [2] == ELF_VER_CHR)
	    {
	      size_t l;

	      /* The @@@ syntax is a special case. It renames the
		 symbol name to versioned_name with one `@' removed.  */
	      l = strlen (&p[3]) + 1;
	      memmove (&p [2], &p[3], l);
	      S_SET_NAME (symp, sy_obj->versioned_name);
	    }
	  else
	    {
	      symbolS *symp2;

	      /* FIXME: Creating a new symbol here is risky.  We're
		 in the final loop over the symbol table.  We can
		 get away with it only because the symbol goes to
		 the end of the list, where the loop will still see
		 it.  It would probably be better to do this in
		 obj_frob_file_before_adjust.  */

	      symp2 = symbol_find_or_make (sy_obj->versioned_name);

	      /* Now we act as though we saw symp2 = sym.  */

	      S_SET_SEGMENT (symp2, S_GET_SEGMENT (symp));

	      /* Subtracting out the frag address here is a hack
		 because we are in the middle of the final loop.  */
	      S_SET_VALUE (symp2,
			   (S_GET_VALUE (symp)
			    - symbol_get_frag (symp)->fr_address));

	      symbol_set_frag (symp2, symbol_get_frag (symp));

	      /* This will copy over the size information.  */
	      copy_symbol_attributes (symp2, symp);

	      if (S_IS_WEAK (symp))
		S_SET_WEAK (symp2);

	      if (S_IS_EXTERNAL (symp))
		S_SET_EXTERNAL (symp2);
	    }
	}
    }

  /* Double check weak symbols.  */
  if (S_IS_WEAK (symp))
    {
      if (S_IS_COMMON (symp))
	as_bad (_("Symbol `%s' can not be both weak and common"),
		S_GET_NAME (symp));
    }

#ifdef TC_MIPS
  /* The Irix 5 and 6 assemblers set the type of any common symbol and
     any undefined non-function symbol to STT_OBJECT.  We try to be
     compatible, since newer Irix 5 and 6 linkers care.  However, we
     only set undefined symbols to be STT_OBJECT if we are on Irix,
     because that is the only time gcc will generate the necessary
     .global directives to mark functions.  */

  if (S_IS_COMMON (symp))
    symbol_get_bfdsym (symp)->flags |= BSF_OBJECT;

  if (strstr (TARGET_OS, "irix") != NULL
      && ! S_IS_DEFINED (symp)
      && (symbol_get_bfdsym (symp)->flags & BSF_FUNCTION) == 0)
    symbol_get_bfdsym (symp)->flags |= BSF_OBJECT;
#endif

#if 0 /* TC_PPC */
  /* If TC_PPC is defined, we used to force the type of a symbol to be
     BSF_OBJECT if it was otherwise unset.  This was required by some
     version of VxWorks.  Thomas de Lellis <[e-mail]> says
     that this is no longer needed, so it is now commented out.  */
  if ((symbol_get_bfdsym (symp)->flags
       & (BSF_FUNCTION | BSF_FILE | BSF_SECTION_SYM)) == 0
      && S_IS_DEFINED (symp))
    symbol_get_bfdsym (symp)->flags |= BSF_OBJECT;
#endif
}

void
elf_frob_file ()
{
  bfd_map_over_sections (stdoutput, adjust_stab_sections, (PTR) 0);

#ifdef elf_tc_final_processing
  elf_tc_final_processing ();
#endif
}

/* It removes any unneeded versioned symbols from the symbol table.  */

void
elf_frob_file_before_adjust ()
{
  if (symbol_rootP)
    {
      symbolS *symp;

      for (symp = symbol_rootP; symp; symp = symbol_next (symp))
	if (symbol_get_obj (symp)->versioned_name)
	  {
	    if (!S_IS_DEFINED (symp))
	      {
		char *p;

		/* The @@@ syntax is a special case. If the symbol is
		   not defined, 2 `@'s will be removed from the
		   versioned_name.  */

		p = strchr (symbol_get_obj (symp)->versioned_name,
			    ELF_VER_CHR);
		know (p != NULL);
		if (p [1] == ELF_VER_CHR && p [2] == ELF_VER_CHR)
		  {
		    size_t l = strlen (&p[3]) + 1;
		    memmove (&p [1], &p[3], l);
		  }
		if (symbol_used_p (symp) == 0
		    && symbol_used_in_reloc_p (symp) == 0)
		  symbol_remove (symp, &symbol_rootP, &symbol_lastP);
	      }
	  }
    }
}

/* It is required that we let write_relocs have the opportunity to
   optimize away fixups before output has begun, since it is possible
   to eliminate all fixups for a section and thus we never should
   have generated the relocation section.  */

void
elf_frob_file_after_relocs ()
{
#ifdef NEED_ECOFF_DEBUG
  if (ECOFF_DEBUGGING)
    /* Generate the ECOFF debugging information.  */
    {
      const struct ecoff_debug_swap *debug_swap;
      struct ecoff_debug_info debug;
      char *buf;
      asection *sec;

      debug_swap
	= get_elf_backend_data (stdoutput)->elf_backend_ecoff_debug_swap;
      know (debug_swap != (const struct ecoff_debug_swap *) NULL);
      ecoff_build_debug (&debug.symbolic_header, &buf, debug_swap);

      /* Set up the pointers in debug.  */
#define SET(ptr, offset, type) \
    debug.ptr = (type) (buf + debug.symbolic_header.offset)

      SET (line, cbLineOffset, unsigned char *);
      SET (external_dnr, cbDnOffset, PTR);
      SET (external_pdr, cbPdOffset, PTR);
      SET (external_sym, cbSymOffset, PTR);
      SET (external_opt, cbOptOffset, PTR);
      SET (external_aux, cbAuxOffset, union aux_ext *);
      SET (ss, cbSsOffset, char *);
      SET (external_fdr, cbFdOffset, PTR);
      SET (external_rfd, cbRfdOffset, PTR);
      /* ssext and external_ext are set up just below.  */

#undef SET

      /* Set up the external symbols.  */
      debug.ssext = debug.ssext_end = NULL;
      debug.external_ext = debug.external_ext_end = NULL;
      if (! bfd_ecoff_debug_externals (stdoutput, &debug, debug_swap, true,
				       elf_get_extr, elf_set_index))
	as_fatal (_("Failed to set up debugging information: %s"),
		  bfd_errmsg (bfd_get_error ()));

      sec = bfd_get_section_by_name (stdoutput, ".mdebug");
      assert (sec != NULL);

      know (stdoutput->output_has_begun == false);

      /* We set the size of the section, call bfd_set_section_contents
	 to force the ELF backend to allocate a file position, and then
	 write out the data.  FIXME: Is this really the best way to do
	 this?  */
      sec->_raw_size = bfd_ecoff_debug_size (stdoutput, &debug, debug_swap);

      /* Pass BUF to bfd_set_section_contents because this will
         eventually become a call to fwrite, and ISO C prohibits
         passing a NULL pointer to a stdio function even if the
         pointer will not be used.  */
      if (! bfd_set_section_contents (stdoutput, sec, (PTR) buf,
				      (file_ptr) 0, (bfd_size_type) 0))
	as_fatal (_("Can't start writing .mdebug section: %s"),
		  bfd_errmsg (bfd_get_error ()));

      know (stdoutput->output_has_begun == true);
      know (sec->filepos != 0);

      if (! bfd_ecoff_write_debug (stdoutput, &debug, debug_swap,
				   sec->filepos))
	as_fatal (_("Could not write .mdebug section: %s"),
		  bfd_errmsg (bfd_get_error ()));
    }
#endif /* NEED_ECOFF_DEBUG */
}

#ifdef SCO_ELF

/* Heavily plagarized from obj_elf_version.  The idea is to emit the
   SCO specific identifier in the .notes section to satisfy the SCO
   linker.

   This looks more complicated than it really is.  As opposed to the
   "obvious" solution, this should handle the cross dev cases
   correctly.  (i.e, hosting on a 64 bit big endian processor, but
   generating SCO Elf code) Efficiency isn't a concern, as there
   should be exactly one of these sections per object module.

   SCO OpenServer 5 identifies it's ELF modules with a standard ELF
   .note section.

   int_32 namesz  = 4 ;  Name size
   int_32 descsz  = 12 ; Descriptive information
   int_32 type    = 1 ;
   char   name[4] = "SCO" ; Originator name ALWAYS SCO + NULL
   int_32 version = (major ver # << 16)  | version of tools ;
   int_32 source  = (tool_id << 16 ) | 1 ;
   int_32 info    = 0 ;    These are set by the SCO tools, but we
                           don't know enough about the source
			   environment to set them.  SCO ld currently
			   ignores them, and recommends we set them
			   to zero.  */

#define SCO_MAJOR_VERSION 0x1
#define SCO_MINOR_VERSION 0x1

void
sco_id ()
{

  char *name;
  unsigned int c;
  char ch;
  char *p;
  asection *seg = now_seg;
  subsegT subseg = now_subseg;
  Elf_Internal_Note i_note;
  Elf_External_Note e_note;
  asection *note_secp = (asection *) NULL;
  int i, len;

  /* create the .note section */

  note_secp = subseg_new (".note", 0);
  bfd_set_section_flags (stdoutput,
			 note_secp,
			 SEC_HAS_CONTENTS | SEC_READONLY);

  /* process the version string */

  i_note.namesz = 4;
  i_note.descsz = 12;		/* 12 descriptive bytes */
  i_note.type = NT_VERSION;	/* Contains a version string */

  p = frag_more (sizeof (i_note.namesz));
  md_number_to_chars (p, (valueT) i_note.namesz, 4);

  p = frag_more (sizeof (i_note.descsz));
  md_number_to_chars (p, (valueT) i_note.descsz, 4);

  p = frag_more (sizeof (i_note.type));
  md_number_to_chars (p, (valueT) i_note.type, 4);

  p = frag_more (4);
  strcpy (p, "SCO");

  /* Note: this is the version number of the ELF we're representing */
  p = frag_more (4);
  md_number_to_chars (p, (SCO_MAJOR_VERSION << 16) | (SCO_MINOR_VERSION), 4);

  /* Here, we pick a magic number for ourselves (yes, I "registered"
     it with SCO.  The bottom bit shows that we are compat with the
     SCO ABI.  */
  p = frag_more (4);
  md_number_to_chars (p, 0x4c520000 | 0x0001, 4);

  /* If we knew (or cared) what the source language options were, we'd
     fill them in here.  SCO has given us permission to ignore these
     and just set them to zero.  */
  p = frag_more (4);
  md_number_to_chars (p, 0x0000, 4);

  frag_align (2, 0, 0);

  /* We probably can't restore the current segment, for there likely
     isn't one yet...  */
  if (seg && subseg)
    subseg_set (seg, subseg);

}

#endif /* SCO_ELF */

static int
elf_separate_stab_sections ()
{
#ifdef NEED_ECOFF_DEBUG
  return (!ECOFF_DEBUGGING);
#else
  return 1;
#endif
}

static void
elf_init_stab_section (seg)
     segT seg;
{
#ifdef NEED_ECOFF_DEBUG
  if (!ECOFF_DEBUGGING)
#endif
    obj_elf_init_stab_section (seg);
}

const struct format_ops elf_format_ops =
{
  bfd_target_elf_flavour,
  0,	/* dfl_leading_underscore */
  1,	/* emit_section_symbols */
  elf_begin,
  elf_file_symbol,
  elf_frob_symbol,
  elf_frob_file,
  elf_frob_file_before_adjust,
  elf_frob_file_after_relocs,
  elf_s_get_size, elf_s_set_size,
  elf_s_get_align, elf_s_set_align,
  elf_s_get_other,
  elf_s_set_other,
  0,	/* s_get_desc */
  0,	/* s_set_desc */
  0,	/* s_get_type */
  0,	/* s_set_type */
  elf_copy_symbol_attributes,
#ifdef NEED_ECOFF_DEBUG
  ecoff_generate_asm_lineno,
  ecoff_stab,
#else
  0,	/* generate_asm_lineno */
  0,	/* process_stab */
#endif
  elf_separate_stab_sections,
  elf_init_stab_section,
  elf_sec_sym_ok_for_reloc,
  elf_pop_insert,
#ifdef NEED_ECOFF_DEBUG
  elf_ecoff_set_ext,
#else
  0,	/* ecoff_set_ext */
#endif
  elf_obj_read_begin_hook,
  elf_obj_symbol_new_hook
};