loader.c

体系机构仿真

	  /* what is this section??? */
	  fatal("encountered unknown section `%s', %d bytes @ 0x%08x",
		bfd_section_name(abfd, sect), bfd_section_size(abfd, sect),
		bfd_section_vma(abfd, sect));
	}
    }

  /* compute data segment size from data break point */
  ld_text_base = SS_TEXT_BASE;
  ld_data_base = SS_DATA_BASE;
  ld_prog_entry = bfd_get_start_address(abfd);
  ld_data_size = data_break - ld_data_base;

  /* done with the executable, close it */
  if (!bfd_close(abfd))
    fatal("could not close executable `%s'", argv[0]);

#else /* !BFD_LOADER, i.e., standalone loader */

  FILE *fobj;
  long floc;
  struct ecoff_filehdr fhdr;
  struct ecoff_aouthdr ahdr;
  struct ecoff_scnhdr shdr;

  /* set up a local stack pointer, this is where the argv and envp
     data is written into program memory */
  ld_stack_base = SS_STACK_BASE;
  sp = ROUND_DOWN(SS_STACK_BASE - SS_MAX_ENVIRON, sizeof(SS_DOUBLE_TYPE));
  ld_stack_size = ld_stack_base - sp;

  /* initial stack pointer value */
  ld_environ_base = sp;

  /* record profile file name */
  ld_prog_fname = argv[0];

  /* load the program into memory, try both endians */
#ifdef __CYGWIN32__
  fobj = fopen(argv[0], "rb");
#else
  fobj = fopen(argv[0], "r");
#endif
  if (!fobj)
    fatal("cannot open executable `%s'", argv[0]);

  if (fread(&fhdr, sizeof(struct ecoff_filehdr), 1, fobj) < 1)
    fatal("cannot read header from executable `%s'", argv[0]);

  /* record endian of target */
  if (fhdr.f_magic == ECOFF_EB_MAGIC)
    ld_target_big_endian = TRUE;
  else if (fhdr.f_magic == ECOFF_EL_MAGIC)
    ld_target_big_endian = FALSE;
  else
    fatal("bad magic number in executable `%s'", argv[0]);

  if (fread(&ahdr, sizeof(struct ecoff_aouthdr), 1, fobj) < 1)
    fatal("cannot read AOUT header from executable `%s'", argv[0]);

  data_break = SS_DATA_BASE + ahdr.dsize + ahdr.bsize;

#if 0
  Data_start = ahdr.data_start;
  Data_size = ahdr.dsize;
  Bss_size = ahdr.bsize;
  Bss_start = ahdr.bss_start;
  Gp_value = ahdr.gp_value;
  Text_entry = ahdr.entry;
#endif

  /* seek to the beginning of the first section header, the file header comes
     first, followed by the optional header (this is the aouthdr), the size
     of the aouthdr is given in Fdhr.f_opthdr */
  fseek(fobj, sizeof(struct ecoff_filehdr) + fhdr.f_opthdr, 0);

  debug("processing %d sections in `%s'...", fhdr.f_nscns, argv[0]);

  /* loop through the section headers */
  floc = ftell(fobj);
  for (i = 0; i < fhdr.f_nscns; i++)
    {
      char *p;

      if (fseek(fobj, floc, 0) == -1)
	fatal("could not reset location in executable");
      if (fread(&shdr, sizeof(struct ecoff_scnhdr), 1, fobj) < 1)
	fatal("could not read section %d from executable", i);
      floc = ftell(fobj);

      switch (shdr.s_flags)
	{
	case ECOFF_STYP_TEXT:
	  ld_text_size = ((shdr.s_vaddr + shdr.s_size) - SS_TEXT_BASE) + 128;

	  p = calloc(shdr.s_size, sizeof(char));
	  if (!p)
	    fatal("out of virtual memory");

	  if (fseek(fobj, shdr.s_scnptr, 0) == -1)
	    fatal("could not read `.text' from executable", i);
	  if (fread(p, shdr.s_size, 1, fobj) < 1)
	    fatal("could not read text section from executable");

	  /* copy program section it into simulator target memory */
	  mem_bcopy(mem_fn, Write, shdr.s_vaddr, p, shdr.s_size);

	  /* release the section buffer */
	  free(p);

#if 0
	  Text_seek = shdr.s_scnptr;
	  Text_start = shdr.s_vaddr;
	  Text_size = shdr.s_size / 4;
	  /* there is a null routine after the supposed end of text */
	  Text_size += 10;
	  Text_end = Text_start + Text_size * 4;
	  /* create_text_reloc(shdr.s_relptr, shdr.s_nreloc); */
#endif
	  break;

	case ECOFF_STYP_RDATA:
	  /* The .rdata section is sometimes placed before the text
	   * section instead of being contiguous with the .data section.
	   */
#if 0
	  Rdata_start = shdr.s_vaddr;
	  Rdata_size = shdr.s_size;
	  Rdata_seek = shdr.s_scnptr;
#endif
	  /* fall through */
	case ECOFF_STYP_DATA:
#if 0
	  Data_seek = shdr.s_scnptr;
#endif
	  /* fall through */
	case ECOFF_STYP_SDATA:
#if 0
	  Sdata_seek = shdr.s_scnptr;
#endif

	  p = calloc(shdr.s_size, sizeof(char));
	  if (!p)
	    fatal("out of virtual memory");

	  if (fseek(fobj, shdr.s_scnptr, 0) == -1)
	    fatal("could not read `.text' from executable", i);
	  if (fread(p, shdr.s_size, 1, fobj) < 1)
	    fatal("could not read text section from executable");

	  /* copy program section it into simulator target memory */
	  mem_bcopy(mem_fn, Write, shdr.s_vaddr, p, shdr.s_size);

	  /* release the section buffer */
	  free(p);

	  break;

	case ECOFF_STYP_BSS:
	  break;

	case ECOFF_STYP_SBSS:
	  break;
        }
    }

  /* compute data segment size from data break point */
  ld_text_base = SS_TEXT_BASE;
  ld_data_base = SS_DATA_BASE;
  ld_prog_entry = ahdr.entry;
  ld_data_size = data_break - ld_data_base;

  /* done with the executable, close it */
  if (fclose(fobj))
    fatal("could not close executable `%s'", argv[0]);

#endif /* BFD_LOADER */

  /* perform sanity checks on segment ranges */
  if (!ld_text_base || !ld_text_size)
    fatal("executable is missing a `.text' section");
  if (!ld_data_base || !ld_data_size)
    fatal("executable is missing a `.data' section");
  if (!ld_prog_entry)
    fatal("program entry point not specified");

  /* determine byte/words swapping required to execute on this host */
  sim_swap_bytes = (endian_host_byte_order() != endian_target_byte_order());
  if (sim_swap_bytes)
    {
#if 0 /* FIXME: disabled until further notice... */
      /* cross-endian is never reliable, why this is so is beyond the scope
	 of this comment, e-mail me for details... */
      fprintf(stderr, "sim: *WARNING*: swapping bytes to match host...\n");
      fprintf(stderr, "sim: *WARNING*: swapping may break your program!\n");
#else
      fatal("binary endian does not match host endian");
#endif
    }
  sim_swap_words = (endian_host_word_order() != endian_target_word_order());
  if (sim_swap_words)
    {
#if 0 /* FIXME: disabled until further notice... */
      /* cross-endian is never reliable, why this is so is beyond the scope
	 of this comment, e-mail me for details... */
      fprintf(stderr, "sim: *WARNING*: swapping words to match host...\n");
      fprintf(stderr, "sim: *WARNING*: swapping may break your program!\n");
#else
      fatal("binary endian does not match host endian");
#endif
    }

  /* write [argc] to stack */
  temp = SWAP_WORD(argc);
  mem_fn(Write, sp, &temp, sizeof(SS_WORD_TYPE));
  sp += sizeof(SS_WORD_TYPE);

  /* skip past argv array and NULL */
  argv_addr = sp;
  sp = sp + (argc + 1) * sizeof(SS_PTR_TYPE);

  /* save space for envp array and NULL */
  envp_addr = sp;
  for (i=0; envp[i]; i++)
    sp += sizeof(SS_PTR_TYPE);
  sp += sizeof(SS_PTR_TYPE);

  /* fill in the argv pointer array and data */
  for (i=0; i<argc; i++)
    {
      /* write the argv pointer array entry */
      temp = SWAP_WORD(sp);
      mem_fn(Write, argv_addr + i*sizeof(SS_PTR_TYPE),
	     &temp, sizeof(SS_PTR_TYPE));
      /* and the data */
      sp += mem_strcpy(mem_fn, Write, sp, argv[i]);
    }
  /* terminate argv array with a NULL */
  mem_fn(Write, argv_addr + i*sizeof(SS_PTR_TYPE),
	 &null_ptr, sizeof(SS_PTR_TYPE));

  /* write envp pointer array and data to stack */
  for (i = 0; envp[i]; i++)
    {
      /* write the envp pointer array entry */
      temp = SWAP_WORD(sp);
      mem_fn(Write, envp_addr + i*sizeof(SS_PTR_TYPE),
	     &temp, sizeof(SS_PTR_TYPE));
      /* and the data */
      sp += mem_strcpy(mem_fn, Write, sp, envp[i]);
    }
  /* terminate the envp array with a NULL */
  mem_fn(Write, envp_addr + i*sizeof(SS_PTR_TYPE),
	       &null_ptr, sizeof(SS_PTR_TYPE));

  /* did we tromp off the stop of the stack? */
  if (sp > ld_stack_base)
    {
      /* we did, indicate to the user that SS_MAX_ENVIRON must be increased,
	 alternatively, you can use a smaller environment, or fewer
	 command line arguments */
      fatal("environment overflow, increase SS_MAX_ENVIRON in ss.h");
    }

  debug("ld_text_base: 0x%08x  ld_text_size: 0x%08x",
	ld_text_base, ld_text_size);
  debug("ld_data_base: 0x%08x  ld_data_size: 0x%08x",
	ld_data_base, ld_data_size);
  debug("ld_stack_base: 0x%08x  ld_stack_size: 0x%08x",
	ld_stack_base, ld_stack_size);
  debug("ld_prog_entry: 0x%08x", ld_prog_entry);

}