elf32-mips.c

基于4个mips核的noc设计

      reloc_entry->addend = relocation - 4;
    }

  /* Now do the LO16 reloc in the usual way.  */
  return bfd_elf_generic_reloc (abfd, reloc_entry, symbol, data,
				input_section, output_bfd, error_message);
}

/* Do a R_MIPS_GOT16 reloc.  This is a reloc against the global offset
   table used for PIC code.  If the symbol is an external symbol, the
   instruction is modified to contain the offset of the appropriate
   entry in the global offset table.  If the symbol is a section
   symbol, the next reloc is a R_MIPS_LO16 reloc.  The two 16 bit
   addends are combined to form the real addend against the section
   symbol; the GOT16 is modified to contain the offset of an entry in
   the global offset table, and the LO16 is modified to offset it
   appropriately.  Thus an offset larger than 16 bits requires a
   modified value in the global offset table.

   This implementation suffices for the assembler, but the linker does
   not yet know how to create global offset tables.  */

bfd_reloc_status_type
_bfd_mips_elf_got16_reloc (abfd,
		      reloc_entry,
		      symbol,
		      data,
		      input_section,
		      output_bfd,
		      error_message)
     bfd *abfd;
     arelent *reloc_entry;
     asymbol *symbol;
     PTR data;
     asection *input_section;
     bfd *output_bfd;
     char **error_message;
{
  /* If we're relocating, and this an external symbol, we don't want
     to change anything.  */
  if (output_bfd != (bfd *) NULL
      && (symbol->flags & BSF_SECTION_SYM) == 0
      && reloc_entry->addend == 0)
    {
      reloc_entry->address += input_section->output_offset;
      return bfd_reloc_ok;
    }

  /* If we're relocating, and this is a local symbol, we can handle it
     just like HI16.  */
  if (output_bfd != (bfd *) NULL
      && (symbol->flags & BSF_SECTION_SYM) != 0)
    return _bfd_mips_elf_hi16_reloc (abfd, reloc_entry, symbol, data,
				     input_section, output_bfd, error_message);

  abort ();
}

/* Set the GP value for OUTPUT_BFD.  Returns false if this is a
   dangerous relocation.  */

static boolean
mips_elf_assign_gp (output_bfd, pgp)
     bfd *output_bfd;
     bfd_vma *pgp;
{
  unsigned int count;
  asymbol **sym;
  unsigned int i;

  /* If we've already figured out what GP will be, just return it.  */
  *pgp = _bfd_get_gp_value (output_bfd);
  if (*pgp)
    return true;

  count = bfd_get_symcount (output_bfd);
  sym = bfd_get_outsymbols (output_bfd);

  /* The linker script will have created a symbol named `_gp' with the
     appropriate value.  */
  if (sym == (asymbol **) NULL)
    i = count;
  else
    {
      for (i = 0; i < count; i++, sym++)
	{
	  register CONST char *name;

	  name = bfd_asymbol_name (*sym);
	  if (*name == '_' && strcmp (name, "_gp") == 0)
	    {
	      *pgp = bfd_asymbol_value (*sym);
	      _bfd_set_gp_value (output_bfd, *pgp);
	      break;
	    }
	}
    }

  if (i >= count)
    {
      /* Only get the error once.  */
      *pgp = 4;
      _bfd_set_gp_value (output_bfd, *pgp);
      return false;
    }

  return true;
}

/* We have to figure out the gp value, so that we can adjust the
   symbol value correctly.  We look up the symbol _gp in the output
   BFD.  If we can't find it, we're stuck.  We cache it in the ELF
   target data.  We don't need to adjust the symbol value for an
   external symbol if we are producing relocateable output.  */

static bfd_reloc_status_type
mips_elf_final_gp (output_bfd, symbol, relocateable, error_message, pgp)
     bfd *output_bfd;
     asymbol *symbol;
     boolean relocateable;
     char **error_message;
     bfd_vma *pgp;
{
  if (bfd_is_und_section (symbol->section)
      && ! relocateable)
    {
      *pgp = 0;
      return bfd_reloc_undefined;
    }

  *pgp = _bfd_get_gp_value (output_bfd);
  if (*pgp == 0
      && (! relocateable
	  || (symbol->flags & BSF_SECTION_SYM) != 0))
    {
      if (relocateable)
	{
	  /* Make up a value.  */
	  *pgp = symbol->section->output_section->vma + 0x4000;
	  _bfd_set_gp_value (output_bfd, *pgp);
	}
      else if (!mips_elf_assign_gp (output_bfd, pgp))
	{
	  *error_message =
	    (char *) _("GP relative relocation when _gp not defined");
	  return bfd_reloc_dangerous;
	}
    }

  return bfd_reloc_ok;
}

/* Do a R_MIPS_GPREL16 relocation.  This is a 16 bit value which must
   become the offset from the gp register.  This function also handles
   R_MIPS_LITERAL relocations, although those can be handled more
   cleverly because the entries in the .lit8 and .lit4 sections can be
   merged.  */

static bfd_reloc_status_type gprel16_with_gp PARAMS ((bfd *, asymbol *,
						      arelent *, asection *,
						      boolean, PTR, bfd_vma));

bfd_reloc_status_type
_bfd_mips_elf_gprel16_reloc (abfd, reloc_entry, symbol, data, input_section,
			     output_bfd, error_message)
     bfd *abfd;
     arelent *reloc_entry;
     asymbol *symbol;
     PTR data;
     asection *input_section;
     bfd *output_bfd;
     char **error_message;
{
  boolean relocateable;
  bfd_reloc_status_type ret;
  bfd_vma gp;

  /* If we're relocating, and this is an external symbol with no
     addend, we don't want to change anything.  We will only have an
     addend if this is a newly created reloc, not read from an ELF
     file.  */
  if (output_bfd != (bfd *) NULL
      && (symbol->flags & BSF_SECTION_SYM) == 0
      && reloc_entry->addend == 0)
    {
      reloc_entry->address += input_section->output_offset;
      return bfd_reloc_ok;
    }

  if (output_bfd != (bfd *) NULL)
    relocateable = true;
  else
    {
      relocateable = false;
      output_bfd = symbol->section->output_section->owner;
    }

  ret = mips_elf_final_gp (output_bfd, symbol, relocateable, error_message,
			   &gp);
  if (ret != bfd_reloc_ok)
    return ret;

  return gprel16_with_gp (abfd, symbol, reloc_entry, input_section,
			  relocateable, data, gp);
}

static bfd_reloc_status_type
gprel16_with_gp (abfd, symbol, reloc_entry, input_section, relocateable, data,
		 gp)
     bfd *abfd;
     asymbol *symbol;
     arelent *reloc_entry;
     asection *input_section;
     boolean relocateable;
     PTR data;
     bfd_vma gp;
{
  bfd_vma relocation;
  unsigned long insn;
  unsigned long val;

  if (bfd_is_com_section (symbol->section))
    relocation = 0;
  else
    relocation = symbol->value;

  relocation += symbol->section->output_section->vma;
  relocation += symbol->section->output_offset;

  if (reloc_entry->address > input_section->_cooked_size)
    return bfd_reloc_outofrange;

  insn = bfd_get_32 (abfd, (bfd_byte *) data + reloc_entry->address);

  /* Set val to the offset into the section or symbol.  */
  if (reloc_entry->howto->src_mask == 0)
    {
      /* This case occurs with the 64-bit MIPS ELF ABI.  */
      val = reloc_entry->addend;
    }
  else
    {
      val = ((insn & 0xffff) + reloc_entry->addend) & 0xffff;
      if (val & 0x8000)
	val -= 0x10000;
    }

  /* Adjust val for the final section location and GP value.  If we
     are producing relocateable output, we don't want to do this for
     an external symbol.  */
  if (! relocateable
      || (symbol->flags & BSF_SECTION_SYM) != 0)
    val += relocation - gp;

  insn = (insn & ~0xffff) | (val & 0xffff);
  bfd_put_32 (abfd, insn, (bfd_byte *) data + reloc_entry->address);

  if (relocateable)
    reloc_entry->address += input_section->output_offset;

  /* Make sure it fit in 16 bits.  */
  if ((long) val >= 0x8000 || (long) val < -0x8000)
    return bfd_reloc_overflow;

  return bfd_reloc_ok;
}

/* Do a R_MIPS_GPREL32 relocation.  Is this 32 bit value the offset
   from the gp register? XXX */

static bfd_reloc_status_type gprel32_with_gp PARAMS ((bfd *, asymbol *,
						      arelent *, asection *,
						      boolean, PTR, bfd_vma));

bfd_reloc_status_type
_bfd_mips_elf_gprel32_reloc (abfd,
			reloc_entry,
			symbol,
			data,
			input_section,
			output_bfd,
			error_message)
     bfd *abfd;
     arelent *reloc_entry;
     asymbol *symbol;
     PTR data;
     asection *input_section;
     bfd *output_bfd;
     char **error_message;
{
  boolean relocateable;
  bfd_reloc_status_type ret;
  bfd_vma gp;

  /* If we're relocating, and this is an external symbol with no
     addend, we don't want to change anything.  We will only have an
     addend if this is a newly created reloc, not read from an ELF
     file.  */
  if (output_bfd != (bfd *) NULL
      && (symbol->flags & BSF_SECTION_SYM) == 0
      && reloc_entry->addend == 0)
    {
      *error_message = (char *)
	_("32bits gp relative relocation occurs for an external symbol");
      return bfd_reloc_outofrange;
    }

  if (output_bfd != (bfd *) NULL)
    {
      relocateable = true;
      gp = _bfd_get_gp_value (output_bfd);
    }
  else
    {
      relocateable = false;
      output_bfd = symbol->section->output_section->owner;

      ret = mips_elf_final_gp (output_bfd, symbol, relocateable,
			       error_message, &gp);
      if (ret != bfd_reloc_ok)
	return ret;
    }

  return gprel32_with_gp (abfd, symbol, reloc_entry, input_section,
			  relocateable, data, gp);
}

static bfd_reloc_status_type
gprel32_with_gp (abfd, symbol, reloc_entry, input_section, relocateable, data,
		 gp)
     bfd *abfd;
     asymbol *symbol;
     arelent *reloc_entry;
     asection *input_section;
     boolean relocateable;
     PTR data;
     bfd_vma gp;
{
  bfd_vma relocation;
  unsigned long val;

  if (bfd_is_com_section (symbol->section))
    relocation = 0;
  else
    relocation = symbol->value;

  relocation += symbol->section->output_section->vma;
  relocation += symbol->section->output_offset;

  if (reloc_entry->address > input_section->_cooked_size)
    return bfd_reloc_outofrange;

  if (reloc_entry->howto->src_mask == 0)
    {
      /* This case arises with the 64-bit MIPS ELF ABI.  */
      val = 0;
    }
  else
    val = bfd_get_32 (abfd, (bfd_byte *) data + reloc_entry->address);

  /* Set val to the offset into the section or symbol.  */
  val += reloc_entry->addend;

  /* Adjust val for the final section location and GP value.  If we
     are producing relocateable output, we don't want to do this for
     an external symbol.  */
  if (! relocateable
      || (symbol->flags & BSF_SECTION_SYM) != 0)
    val += relocation - gp;

  bfd_put_32 (abfd, val, (bfd_byte *) data + reloc_entry->address);

  if (relocateable)
    reloc_entry->address += input_section->output_offset;

  return bfd_reloc_ok;
}

/* Handle a 64 bit reloc in a 32 bit MIPS ELF file.  These are
   generated when addresses are 64 bits.  The upper 32 bits are a simple
   sign extension.  */

static bfd_reloc_status_type
mips32_64bit_reloc (abfd, reloc_entry, symbol, data, input_section,
		    output_bfd, error_message)
     bfd *abfd;
     arelent *reloc_entry;
     asymbol *symbol;
     PTR data;
     asection *input_section;
     bfd *output_bfd;
     char **error_message;
{
  bfd_reloc_status_type r;
  arelent reloc32;
  unsigned long val;
  bfd_size_type addr;

  r = bfd_elf_generic_reloc (abfd, reloc_entry, symbol, data,
			     input_section, output_bfd, error_message);
  if (r != bfd_reloc_continue)
    return r;

  /* Do a normal 32 bit relocation on the lower 32 bits.  */
  reloc32 = *reloc_entry;
  if (bfd_big_endian (abfd))
    reloc32.address += 4;
  reloc32.howto = &elf_mips_howto_table[R_MIPS_32];
  r = bfd_perform_relocation (abfd, &reloc32, data, input_section,
			      output_bfd, error_message);

  /* Sign extend into the upper 32 bits.  */
  val = bfd_get_32 (abfd, (bfd_byte *) data + reloc32.address);
  if ((val & 0x80000000) != 0)
    val = 0xffffffff;
  else
    val = 0;
  addr = reloc_entry->address;
  if (bfd_little_endian (abfd))
    addr += 4;
  bfd_put_32 (abfd, val, (bfd_byte *) data + addr);

  return r;
}

/* Handle a mips16 jump.  */

static bfd_reloc_status_type
mips16_jump_reloc (abfd, reloc_entry, symbol, data, input_section,
		   output_bfd, error_message)