obj-elf.c

基于4个mips核的noc设计

  do
    {
      name = input_line_pointer;
      c = get_symbol_end ();
      symbolP = symbol_find_or_make (name);
      *input_line_pointer = c;

      SKIP_WHITESPACE ();

      bfdsym = symbol_get_bfdsym (symbolP);
      elfsym = elf_symbol_from (bfd_asymbol_bfd (bfdsym), bfdsym);

      assert (elfsym);

      elfsym->internal_elf_sym.st_other = visibility;

      if (c == ',')
	{
	  input_line_pointer ++;

	  SKIP_WHITESPACE ();

	  if (*input_line_pointer == '\n')
	    c = '\n';
	}
    }
  while (c == ',');

  demand_empty_rest_of_line ();
}

static segT previous_section;
static int previous_subsection;

struct section_stack
{
  struct section_stack *next;
  segT seg, prev_seg;
  int subseg, prev_subseg;
};

static struct section_stack *section_stack;

/* Handle the .section pseudo-op.  This code supports two different
   syntaxes.

   The first is found on Solaris, and looks like
       .section ".sec1",#alloc,#execinstr,#write
   Here the names after '#' are the SHF_* flags to turn on for the
   section.  I'm not sure how it determines the SHT_* type (BFD
   doesn't really give us control over the type, anyhow).

   The second format is found on UnixWare, and probably most SVR4
   machines, and looks like
       .section .sec1,"a",@progbits
   The quoted string may contain any combination of a, w, x, and
   represents the SHF_* flags to turn on for the section.  The string
   beginning with '@' can be progbits or nobits.  There should be
   other possibilities, but I don't know what they are.  In any case,
   BFD doesn't really let us set the section type.  */

/* Certain named sections have particular defined types, listed on p.
   4-19 of the ABI.  */
struct special_section
{
  const char *name;
  int type;
  int attributes;
};

static struct special_section const special_sections[] =
{
  { ".bss",	SHT_NOBITS,	SHF_ALLOC + SHF_WRITE		},
  { ".comment",	SHT_PROGBITS,	0				},
  { ".data",	SHT_PROGBITS,	SHF_ALLOC + SHF_WRITE		},
  { ".data1",	SHT_PROGBITS,	SHF_ALLOC + SHF_WRITE		},
  { ".debug",	SHT_PROGBITS,	0				},
  { ".fini",	SHT_PROGBITS,	SHF_ALLOC + SHF_EXECINSTR	},
  { ".init",	SHT_PROGBITS,	SHF_ALLOC + SHF_EXECINSTR	},
  { ".line",	SHT_PROGBITS,	0				},
  { ".note",	SHT_NOTE,	0				},
  { ".rodata",	SHT_PROGBITS,	SHF_ALLOC			},
  { ".rodata1",	SHT_PROGBITS,	SHF_ALLOC			},
  { ".text",	SHT_PROGBITS,	SHF_ALLOC + SHF_EXECINSTR	},

#ifdef ELF_TC_SPECIAL_SECTIONS
  ELF_TC_SPECIAL_SECTIONS
#endif

#if 0
  /* The following section names are special, but they can not
     reasonably appear in assembler code.  Some of the attributes are
     processor dependent.  */
  { ".dynamic",	SHT_DYNAMIC,	SHF_ALLOC /* + SHF_WRITE */ 	},
  { ".dynstr",	SHT_STRTAB,	SHF_ALLOC			},
  { ".dynsym",	SHT_DYNSYM,	SHF_ALLOC			},
  { ".got",	SHT_PROGBITS,	0				},
  { ".hash",	SHT_HASH,	SHF_ALLOC			},
  { ".interp",	SHT_PROGBITS,	/* SHF_ALLOC */			},
  { ".plt",	SHT_PROGBITS,	0				},
  { ".shstrtab",SHT_STRTAB,	0				},
  { ".strtab",	SHT_STRTAB,	/* SHF_ALLOC */			},
  { ".symtab",	SHT_SYMTAB,	/* SHF_ALLOC */			},
#endif

  { NULL,	0,		0				}
};

void
obj_elf_change_section (name, type, attr, push)
     char *name;
     int type, attr, push;
{
  asection *old_sec;
  segT sec;
  flagword flags;
  int i;

#ifdef md_flush_pending_output
  md_flush_pending_output ();
#endif

  /* Switch to the section, creating it if necessary.  */
  if (push)
    {
      struct section_stack *elt;
      elt = xmalloc (sizeof (struct section_stack));
      elt->next = section_stack;
      elt->seg = now_seg;
      elt->prev_seg = previous_section;
      elt->subseg = now_subseg;
      elt->prev_subseg = previous_subsection;
      section_stack = elt;
    }
  previous_section = now_seg;
  previous_subsection = now_subseg;

  old_sec = bfd_get_section_by_name (stdoutput, name);
  sec = subseg_new (name, 0);

  /* See if this is one of the special sections.  */
  for (i = 0; special_sections[i].name != NULL; i++)
    if (strcmp (name, special_sections[i].name) == 0)
      {
	if (type == SHT_NULL)
	  type = special_sections[i].type;
	else if (type != special_sections[i].type)
	  {
	    if (old_sec == NULL)
	      {
		as_warn (_("Setting incorrect section type for %s"), name);
	      }
	    else
	      {
		as_warn (_("Ignoring incorrect section type for %s"), name);
		type = special_sections[i].type;
	      }
	  }
	if ((attr &~ special_sections[i].attributes) != 0
	    && old_sec == NULL)
	  {
	    /* As a GNU extension, we permit a .note section to be
	       allocatable.  If the linker sees an allocateable .note
	       section, it will create a PT_NOTE segment in the output
	       file.  */
	    if (strcmp (name, ".note") != 0
		|| attr != SHF_ALLOC)
	      as_warn (_("Setting incorrect section attributes for %s"),
		       name);
	  }
	attr |= special_sections[i].attributes;
	break;
      }

  /* Convert ELF type and flags to BFD flags.  */
  flags = (SEC_RELOC
	   | ((attr & SHF_WRITE) ? 0 : SEC_READONLY)
	   | ((attr & SHF_ALLOC) ? SEC_ALLOC : 0)
	   | (((attr & SHF_ALLOC) && type != SHT_NOBITS) ? SEC_LOAD : 0)
	   | ((attr & SHF_EXECINSTR) ? SEC_CODE : 0));
#ifdef md_elf_section_flags
  flags = md_elf_section_flags (flags, attr, type);
#endif

  if (old_sec == NULL)
    {
      symbolS *secsym;

      /* Prevent SEC_HAS_CONTENTS from being inadvertently set.  */
      if (type == SHT_NOBITS)
        seg_info (sec)->bss = 1;

      bfd_set_section_flags (stdoutput, sec, flags);

      /* Add a symbol for this section to the symbol table.  */
      secsym = symbol_find (name);
      if (secsym != NULL)
	symbol_set_bfdsym (secsym, sec->symbol);
      else
        symbol_table_insert (section_symbol (sec));
    }
  else if (attr != 0)
    {
      /* If section attributes are specified the second time we see a
	 particular section, then check that they are the same as we
	 saw the first time.  */
      if ((old_sec->flags ^ flags)
	  & (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE
	     | SEC_EXCLUDE | SEC_SORT_ENTRIES))
	as_warn (_("Ignoring changed section attributes for %s"), name);
    }

#ifdef md_elf_section_change_hook
  md_elf_section_change_hook ();
#endif
}

int
obj_elf_parse_section_letters (str, len)
     char *str;
     size_t len;
{
  int attr = 0;

  while (len > 0)
    {
      switch (*str)
	{
	case 'a':
	  attr |= SHF_ALLOC;
	  break;
	case 'w':
	  attr |= SHF_WRITE;
	  break;
	case 'x':
	  attr |= SHF_EXECINSTR;
	  break;
	default:
	  {
	    char *bad_msg = _("Unrecognized .section attribute: want a,w,x");
#ifdef md_elf_section_letter
	    int md_attr = md_elf_section_letter (*str, &bad_msg);
	    if (md_attr >= 0)
	      attr |= md_attr;
	    else
#endif
	      {
		as_warn ("%s", bad_msg);
		attr = -1;
	      }
	  }
	  break;
	}
      str++, len--;
    }

  return attr;
}

int
obj_elf_section_word (str, len)
     char *str;
     size_t len;
{
  if (len == 5 && strncmp (str, "write", 5) == 0)
    return SHF_WRITE;
  if (len == 5 && strncmp (str, "alloc", 5) == 0)
    return SHF_ALLOC;
  if (len == 9 && strncmp (str, "execinstr", 9) == 0)
    return SHF_EXECINSTR;

#ifdef md_elf_section_word
  {
    int md_attr = md_elf_section_word (str, len);
    if (md_attr >= 0)
      return md_attr;
  }
#endif

  as_warn (_("Unrecognized section attribute"));
  return 0;
}

int
obj_elf_section_type (str, len)
     char *str;
     size_t len;
{
  if (len == 8 && strncmp (str, "progbits", 8) == 0)
    return SHT_PROGBITS;
  if (len == 6 && strncmp (str, "nobits", 6) == 0)
    return SHT_NOBITS;

#ifdef md_elf_section_type
  {
    int md_type = md_elf_section_type (str, len);
    if (md_type >= 0)
      return md_type;
  }
#endif

  as_warn (_("Unrecognized section type"));
  return 0;
}

void
obj_elf_section (push)
     int push;
{
  char *name, *beg, *end;
  int type, attr, dummy;

#ifndef TC_I370
  if (flag_mri)
    {
      char mri_type;

#ifdef md_flush_pending_output
      md_flush_pending_output ();
#endif

      previous_section = now_seg;
      previous_subsection = now_subseg;

      s_mri_sect (&mri_type);

#ifdef md_elf_section_change_hook
      md_elf_section_change_hook ();
#endif

      return;
    }
#endif /* ! defined (TC_I370) */

  /* Get name of section.  */
  SKIP_WHITESPACE ();
  if (*input_line_pointer == '"')
    {
      name = demand_copy_C_string (&dummy);
      if (name == NULL)
	{
	  ignore_rest_of_line ();
	  return;
	}
    }
  else
    {
      end = input_line_pointer;
      while (0 == strchr ("\n\t,; ", *end))
	end++;
      if (end == input_line_pointer)
	{
	  as_warn (_("Missing section name"));
	  ignore_rest_of_line ();
	  return;
	}

      name = xmalloc (end - input_line_pointer + 1);
      memcpy (name, input_line_pointer, end - input_line_pointer);
      name[end - input_line_pointer] = '\0';
      input_line_pointer = end;
    }
  SKIP_WHITESPACE ();

  type = SHT_NULL;
  attr = 0;

  if (*input_line_pointer == ',')
    {
      /* Skip the comma.  */
      ++input_line_pointer;
      SKIP_WHITESPACE ();

      if (*input_line_pointer == '"')
	{
	  beg = demand_copy_C_string (&dummy);
	  if (beg == NULL)
	    {
	      ignore_rest_of_line ();
	      return;
	    }
	  attr |= obj_elf_parse_section_letters (beg, strlen (beg));

	  SKIP_WHITESPACE ();
	  if (*input_line_pointer == ',')
	    {
	      char c;
	      ++input_line_pointer;
	      SKIP_WHITESPACE ();
	      c = *input_line_pointer;
	      if (c == '"')
		{
		  beg = demand_copy_C_string (&dummy);
		  if (beg == NULL)
		    {
		      ignore_rest_of_line ();
		      return;
		    }
		  type = obj_elf_section_type (beg, strlen (beg));
		}
	      else if (c == '@' || c == '%')
		{
		  beg = ++input_line_pointer;
		  c = get_symbol_end ();
		  *input_line_pointer = c;
		  type = obj_elf_section_type (beg, input_line_pointer - beg);
		}
	    }
	}
      else
	{
	  do
	    {
	      char c;

	      SKIP_WHITESPACE ();
	      if (*input_line_pointer != '#')
		{
		  as_warn (_("Bad .section directive - character following name is not '#'"));
		  ignore_rest_of_line ();
		  return;
		}
	      beg = ++input_line_pointer;
	      c = get_symbol_end ();
	      *input_line_pointer = c;

	      attr |= obj_elf_section_word (beg, input_line_pointer - beg);

	      SKIP_WHITESPACE ();
	    }
	  while (*input_line_pointer++ == ',');
	  --input_line_pointer;
	}
    }

  demand_empty_rest_of_line ();

  obj_elf_change_section (name, type, attr, push);
}

/* Change to the .data section.  */

void
obj_elf_data (i)
     int i;
{
#ifdef md_flush_pending_output
  md_flush_pending_output ();
#endif

  previous_section = now_seg;
  previous_subsection = now_subseg;
  s_data (i);

#ifdef md_elf_section_change_hook
  md_elf_section_change_hook ();
#endif
}

/* Change to the .text section.  */

void
obj_elf_text (i)
     int i;
{
#ifdef md_flush_pending_output
  md_flush_pending_output ();
#endif

  previous_section = now_seg;
  previous_subsection = now_subseg;
  s_text (i);

#ifdef md_elf_section_change_hook
  md_elf_section_change_hook ();
#endif
}

static void
obj_elf_subsection (ignore)
     int ignore ATTRIBUTE_UNUSED;
{
  register int temp;

#ifdef md_flush_pending_output
  md_flush_pending_output ();
#endif

  previous_section = now_seg;
  previous_subsection = now_subseg;

  temp = get_absolute_expression ();
  subseg_set (now_seg, (subsegT) temp);
  demand_empty_rest_of_line ();

#ifdef md_elf_section_change_hook
  md_elf_section_change_hook ();
#endif
}

/* This can be called from the processor backends if they change
   sections.  */

void
obj_elf_section_change_hook ()
{
  previous_section = now_seg;
  previous_subsection = now_subseg;
}

void
obj_elf_previous (ignore)
     int ignore ATTRIBUTE_UNUSED;