elf64-x86-64.c

基于4个mips核的noc设计

	    }
	}
      else if (strncmp (name, ".rela", 5) == 0)
	{
	  if (s->_raw_size == 0)
	    {
	      /* If we don't need this section, strip it from the
		 output file.  This is mostly to handle .rela.bss and
		 .rela.plt.  We must create both sections in
		 create_dynamic_sections, because they must be created
		 before the linker maps input sections to output
		 sections.  The linker does that before
		 adjust_dynamic_symbol is called, and it is that
		 function which decides whether anything needs to go
		 into these sections.  */
	      strip = true;
	    }
	  else
	    {
	      asection *target;

	      /* Remember whether there are any reloc sections other
		 than .rela.plt.  */
	      if (strcmp (name, ".rela.plt") != 0)
		{
		  const char *outname;

		  relocs = true;

		  /* If this relocation section applies to a read only
		     section, then we probably need a DT_TEXTREL
		     entry.  The entries in the .rela.plt section
		     really apply to the .got section, which we
		     created ourselves and so know is not readonly.  */
		  outname = bfd_get_section_name (output_bfd,
						  s->output_section);
		  target = bfd_get_section_by_name (output_bfd, outname + 5);
		  if (target != NULL
		      && (target->flags & SEC_READONLY) != 0
		      && (target->flags & SEC_ALLOC) != 0)
		    reltext = true;
		}

	      /* We use the reloc_count field as a counter if we need
		 to copy relocs into the output file.  */
	      s->reloc_count = 0;
	    }
	}
      else if (strncmp (name, ".got", 4) != 0)
	{
	  /* It's not one of our sections, so don't allocate space.  */
	  continue;
	}

      if (strip)
	{
	  _bfd_strip_section_from_output (info, s);
	  continue;
	}

      /* Allocate memory for the section contents.  We use bfd_zalloc
	 here in case unused entries are not reclaimed before the
	 section's contents are written out.  This should not happen,
	 but this way if it does, we get a R_X86_64_NONE reloc instead
	 of garbage.  */
      s->contents = (bfd_byte *) bfd_zalloc (dynobj, s->_raw_size);
      if (s->contents == NULL && s->_raw_size != 0)
	return false;
    }

  if (elf_hash_table (info)->dynamic_sections_created)
    {
      /* Add some entries to the .dynamic section.  We fill in the
	 values later, in elf64_x86_64_finish_dynamic_sections, but we
	 must add the entries now so that we get the correct size for
	 the .dynamic section.	The DT_DEBUG entry is filled in by the
	 dynamic linker and used by the debugger.  */
      if (! info->shared)
	{
	  if (! bfd_elf64_add_dynamic_entry (info, DT_DEBUG, 0))
	    return false;
	}

      if (plt)
	{
	  if (! bfd_elf64_add_dynamic_entry (info, DT_PLTGOT, 0)
	      || ! bfd_elf64_add_dynamic_entry (info, DT_PLTRELSZ, 0)
	      || ! bfd_elf64_add_dynamic_entry (info, DT_PLTREL, DT_RELA)
	      || ! bfd_elf64_add_dynamic_entry (info, DT_JMPREL, 0))
	    return false;
	}

      if (relocs)
	{
	  if (! bfd_elf64_add_dynamic_entry (info, DT_RELA, 0)
	      || ! bfd_elf64_add_dynamic_entry (info, DT_RELASZ, 0)
	      || ! bfd_elf64_add_dynamic_entry (info, DT_RELAENT,
						sizeof (Elf64_External_Rela)))
	    return false;
	}

      if (reltext)
	{
	  if (! bfd_elf64_add_dynamic_entry (info, DT_TEXTREL, 0))
	    return false;
	  info->flags |= DF_TEXTREL;
	}
    }

  return true;
}

/* This function is called via elf64_x86_64_link_hash_traverse if we are
   creating a shared object.  In the -Bsymbolic case, it discards the
   space allocated to copy PC relative relocs against symbols which
   are defined in regular objects.  For the normal non-symbolic case,
   we also discard space for relocs that have become local due to
   symbol visibility changes.  We allocated space for them in the
   check_relocs routine, but we won't fill them in in the
   relocate_section routine.  */

static boolean
elf64_x86_64_discard_copies (h, inf)
     struct elf64_x86_64_link_hash_entry *h;
     PTR inf;
{
  struct elf64_x86_64_pcrel_relocs_copied *s;
  struct bfd_link_info *info = (struct bfd_link_info *) inf;

  /* If a symbol has been forced local or we have found a regular
     definition for the symbolic link case, then we won't be needing
     any relocs.  */
  if ((h->root.elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) != 0
      && ((h->root.elf_link_hash_flags & ELF_LINK_FORCED_LOCAL) != 0
	  || info->symbolic))
    {
      for (s = h->pcrel_relocs_copied; s != NULL; s = s->next)
	s->section->_raw_size -= s->count * sizeof (Elf64_External_Rela);
    }

  return true;
}

/* Relocate an x86_64 ELF section.  */

static boolean
elf64_x86_64_relocate_section (output_bfd, info, input_bfd, input_section,
			       contents, relocs, local_syms, local_sections)
     bfd *output_bfd;
     struct bfd_link_info *info;
     bfd *input_bfd;
     asection *input_section;
     bfd_byte *contents;
     Elf_Internal_Rela *relocs;
     Elf_Internal_Sym *local_syms;
     asection **local_sections;
{
  bfd *dynobj;
  Elf_Internal_Shdr *symtab_hdr;
  struct elf_link_hash_entry **sym_hashes;
  bfd_vma *local_got_offsets;
  asection *sgot;
  asection *splt;
  asection *sreloc;
  Elf_Internal_Rela *rela;
  Elf_Internal_Rela *relend;

  dynobj = elf_hash_table (info)->dynobj;
  symtab_hdr = &elf_tdata (input_bfd)->symtab_hdr;
  sym_hashes = elf_sym_hashes (input_bfd);
  local_got_offsets = elf_local_got_offsets (input_bfd);

  sreloc = splt = sgot = NULL;
  if (dynobj != NULL)
    {
      splt = bfd_get_section_by_name (dynobj, ".plt");
      sgot = bfd_get_section_by_name (dynobj, ".got");
    }

  rela = relocs;
  relend = relocs + input_section->reloc_count;
  for (; rela < relend; rela++)
    {
      int r_type;
      reloc_howto_type *howto;
      unsigned long r_symndx;
      struct elf_link_hash_entry *h;
      Elf_Internal_Sym *sym;
      asection *sec;
      bfd_vma relocation;
      bfd_reloc_status_type r;
      unsigned int indx;

      r_type = ELF64_R_TYPE (rela->r_info);

      if ((indx = (unsigned) r_type) >= R_X86_64_max)
	{
	  bfd_set_error (bfd_error_bad_value);
	  return false;
	}
      howto = x86_64_elf_howto_table + indx;

      r_symndx = ELF64_R_SYM (rela->r_info);

      if (info->relocateable)
	{
	  /* This is a relocateable link.  We don't have to change
	     anything, unless the reloc is against a section symbol,
	     in which case we have to adjust according to where the
	     section symbol winds up in the output section.  */
	  if (r_symndx < symtab_hdr->sh_info)
	    {
	      sym = local_syms + r_symndx;
	      if (ELF_ST_TYPE (sym->st_info) == STT_SECTION)
		{
		  sec = local_sections[r_symndx];
		  rela->r_addend += sec->output_offset + sym->st_value;
		}
	    }

	  continue;
	}

      /* This is a final link.	*/
      h = NULL;
      sym = NULL;
      sec = NULL;
      if (r_symndx < symtab_hdr->sh_info)
	{
	  sym = local_syms + r_symndx;
	  sec = local_sections[r_symndx];
	  relocation = (sec->output_section->vma
			+ sec->output_offset
			+ sym->st_value);
	}
      else
	{
	  h = sym_hashes[r_symndx - symtab_hdr->sh_info];
	  while (h->root.type == bfd_link_hash_indirect
		 || h->root.type == bfd_link_hash_warning)
	    h = (struct elf_link_hash_entry *) h->root.u.i.link;
	  if (h->root.type == bfd_link_hash_defined
	      || h->root.type == bfd_link_hash_defweak)
	    {
	      sec = h->root.u.def.section;
	      if ((r_type == R_X86_64_PLT32
		   && splt != NULL
		   && h->plt.offset != (bfd_vma) -1)
		  || ((r_type == R_X86_64_GOT32 || r_type == R_X86_64_GOTPCREL)
		      && elf_hash_table (info)->dynamic_sections_created
		      && (!info->shared
			  || (! info->symbolic && h->dynindx != -1)
			  || (h->elf_link_hash_flags
			      & ELF_LINK_HASH_DEF_REGULAR) == 0))
		  || (info->shared
		      && ((! info->symbolic && h->dynindx != -1)
			  || (h->elf_link_hash_flags
			      & ELF_LINK_HASH_DEF_REGULAR) == 0)
		      && (r_type == R_X86_64_8
			  || r_type == R_X86_64_16
			  || r_type == R_X86_64_32
			  || r_type == R_X86_64_64
			  || r_type == R_X86_64_PC8
			  || r_type == R_X86_64_PC16
			  || r_type == R_X86_64_PC32)
                      && ((input_section->flags & SEC_ALLOC) != 0
                          /* DWARF will emit R_X86_64_32 relocations in its
                             sections against symbols defined externally
                             in shared libraries.  We can't do anything
                             with them here.  */
                          || ((input_section->flags & SEC_DEBUGGING) != 0
			      && (h->elf_link_hash_flags
				  & ELF_LINK_HASH_DEF_DYNAMIC) != 0))))
		{
		  /* In these cases, we don't need the relocation
                     value.  We check specially because in some
                     obscure cases sec->output_section will be NULL.  */
		  relocation = 0;
		}
	      else if (sec->output_section == NULL)
		{
		  (*_bfd_error_handler)
		    (_("%s: warning: unresolvable relocation against symbol `%s' from %s section"),
		     bfd_get_filename (input_bfd), h->root.root.string,
		     bfd_get_section_name (input_bfd, input_section));
		  relocation = 0;
		}
	      else
		relocation = (h->root.u.def.value
			      + sec->output_section->vma
			      + sec->output_offset);
	    }
	  else if (h->root.type == bfd_link_hash_undefweak)
	    relocation = 0;
	  else if (info->shared && !info->symbolic && !info->no_undefined
		   && ELF_ST_VISIBILITY (h->other) == STV_DEFAULT)
	    relocation = 0;
	  else
	    {
	      if (! ((*info->callbacks->undefined_symbol)
		     (info, h->root.root.string, input_bfd,
		      input_section, rela->r_offset,
		      (!info->shared || info->no_undefined
		       || ELF_ST_VISIBILITY (h->other)))))
		return false;
	      relocation = 0;
	    }
	}

      /* When generating a shared object, the relocations handled here are
	 copied into the output file to be resolved at run time.  */
      switch (r_type)
	{
	case R_X86_64_GOT32:
	  /* Relocation is to the entry for this symbol in the global
	     offset table.  */
	case R_X86_64_GOTPCREL:
	  /* Use global offset table as symbol value.  */
	  BFD_ASSERT (sgot != NULL);

	  if (h != NULL)
	    {
	      bfd_vma off = h->got.offset;
	      BFD_ASSERT (off != (bfd_vma) -1);

	      if (! elf_hash_table (info)->dynamic_sections_created
		  || (info->shared
		      && (info->symbolic || h->dynindx == -1)
		      && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR)))
		{
		  /* This is actually a static link, or it is a -Bsymbolic
		     link and the symbol is defined locally, or the symbol
		     was forced to be local because of a version file.	We
		     must initialize this entry in the global offset table.
		     Since the offset must always be a multiple of 8, we
		     use the least significant bit to record whether we
		     have initialized it already.

		     When doing a dynamic link, we create a .rela.got
		     relocation entry to initialize the value.	This is
		     done in the finish_dynamic_symbol routine.	 */
		  if ((off & 1) != 0)
		    off &= ~1;
		  else
		    {
		      bfd_put_64 (output_bfd, relocation,
				  sgot->contents + off);
		      h->got.offset |= 1;
		    }
		}
	      if (r_type == R_X86_64_GOTPCREL)
		relocation = sgot->output_section->vma + sgot->output_offset + off;
	      else
		relocation = sgot->output_offset + off;
	    }
	  else
	    {
	      bfd_vma off;

	      BFD_ASSERT (local_got_offsets != NULL
			  && local_got_offsets[r_symndx] != (bfd_vma) -1);

	      off = local_got_offsets[r_symndx];

	      /* The offset must always be a multiple of 8.  We use
		 the least significant bit to record whether we have
		 already generated the necessary reloc.	 */
	      if ((off & 1) != 0)
		off &= ~1;
	      else
		{
		  bfd_put_64 (output_bfd, relocation, sgot->contents + off);

		  if (info->shared)
		    {
		      asection *srelgot;
		      Elf_Internal_Rela outrel;

		      /* We need to generate a R_X86_64_RELATIVE reloc
			 for the dynamic linker.  */
		      srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
		      BFD_ASSERT (srelgot != NULL);

		      outrel.r_offset = (sgot->output_section->vma
					 + sgot->output_offset
					 + off);
		      outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
		      outrel.r_addend = relocation;
		      bfd_elf64_swap_reloca_out (output_bfd, &outrel,
						 (((Elf64_External_Rela *)
						   srelgot->contents)
						  + srelgot->reloc_count));
		      ++srelgot->reloc_count;
		    }

		  local_got_offsets[r_symndx] |= 1;
		}

	      if (r_type == R_X86_64_GOTPCREL)
		relocation = sgot->output_section->vma + sgot->output_offset + off;
	      else
		relocation = sgot->output_offset + off;
	    }

	  break;

	case R_X86_64_PLT32:
	  /* Relocation is to the entry for this symbol in the
	     procedure linkage table.  */

	  /* Resolve a PLT32 reloc against a local symbol directly,
	     without using the procedure linkage table.	 */
	  if (h == NULL)
	    break;

	  if (h->plt.offset == (bfd_vma) -1 || splt == NULL)
	    {
	      /* We didn't make a PLT entry for this symbol.  This
		 happens when statically linking PIC code, or when
		 using -Bsymbolic.  */
	      break;
	    }

	  relocation = (splt->output_section->vma
			+ splt->output_offset
			+ h->plt.offset);
	  break;

	case R_X86_64_PC8:
	case R_X86_64_PC16:
	case R_X86_64_PC32:
	  if (h == NULL)
	    break;
	  /* Fall through.  */
	case R_X86_64_8:
	case R_X86_64_16:
	case R_X86_64_32:
	case R_X86_64_64:
	  /* FIXME: The ABI says the linker should make sure the value is
	     the same when it's zeroextended to 64 bit.	 */
	  if (info->shared
	      && (input_section->flags & SEC_ALLOC) != 0
	      && ((r_type != R_X86_64_PC8
		   && r_type != R_X86_64_PC16
		   && r_type != R_X86_64_PC32)
		  || (! info->symbolic
		      || (h->elf_link_hash_flags
			  & ELF_LINK_HASH_DEF_REGULAR) == 0)))

	    {
	      Elf_Internal_Rela outrel;
	      boolean skip, relocate;

	      /* When generating a shared object, these relocations
		 are copied into the output file to be resolved at run
		 time.	*/

	      if (sreloc == NULL)
		{
		  const char *name;

		  name = (bfd_elf_string_from_elf_section
			  (input_bfd,
			   elf_elfheader (input_bfd)->e_shstrndx,
			   elf_section_data (input_section)->rel_hdr.sh_name));
		  if (name == NULL)
		    return false;

		  BFD_ASSERT (strncmp (name, ".rela", 5) == 0
			      && strcmp (bfd_get_section_name (input_bfd,
							       input_section),
					 name + 5) == 0);

		  sreloc = bfd_get_section_by_name (dynobj, name);
		  BFD_ASSERT (sreloc != NULL);
		}

	      skip = false;

	      if (elf_section_data (input_section)->stab_info == NULL)
		outrel.r_offset = rela->r_offset;
	      else
		{
		  bfd_vma off;