dl-machine.c

Glibc 2.3.2源代码(解压后有100多M)

	  while (i < num_plt_entries && i < PLT_DOUBLE_SIZE)
	    {
	      plt[offset  ] = OPCODE_LI (11, i * 4);
	      plt[offset+1] = OPCODE_B ((PLT_TRAMPOLINE_ENTRY_WORDS + 2
					 - (offset+1))
					* 4);
	      i++;
	      offset += 2;
	    }
	  while (i < num_plt_entries)
	    {
	      plt[offset  ] = OPCODE_LIS_HI (11, i * 4 + data_words);
	      plt[offset+1] = OPCODE_LWZU (12, i * 4 + data_words, 11);
	      plt[offset+2] = OPCODE_B ((PLT_TRAMPOLINE_ENTRY_WORDS
					 - (offset+2))
					* 4);
	      plt[offset+3] = OPCODE_BCTR ();
	      i++;
	      offset += 4;
	    }
	}

      /* Now, we've modified code.  We need to write the changes from
	 the data cache to a second-level unified cache, then make
	 sure that stale data in the instruction cache is removed.
	 (In a multiprocessor system, the effect is more complex.)
	 Most of the PLT shouldn't be in the instruction cache, but
	 there may be a little overlap at the start and the end.

	 Assumes that dcbst and icbi apply to lines of 16 bytes or
	 more.  Current known line sizes are 16, 32, and 128 bytes.  */

      size_modified = lazy ? rel_offset_words : 6;
      for (i = 0; i < size_modified; i += 4)
	PPC_DCBST (plt + i);
      PPC_DCBST (plt + size_modified - 1);
      PPC_SYNC;
      PPC_ICBI (plt);
      PPC_ICBI (plt + size_modified - 1);
      PPC_ISYNC;
    }

  return lazy;
}

Elf32_Addr
__elf_machine_fixup_plt(struct link_map *map, const Elf32_Rela *reloc,
			Elf32_Addr *reloc_addr, Elf32_Addr finaladdr)
{
  Elf32_Sword delta = finaladdr - (Elf32_Word) reloc_addr;
  if (delta << 6 >> 6 == delta)
    *reloc_addr = OPCODE_B (delta);
  else if (finaladdr <= 0x01fffffc || finaladdr >= 0xfe000000)
    *reloc_addr = OPCODE_BA (finaladdr);
  else
    {
      Elf32_Word *plt, *data_words;
      Elf32_Word index, offset, num_plt_entries;

      num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val
			 / sizeof(Elf32_Rela));
      plt = (Elf32_Word *) D_PTR (map, l_info[DT_PLTGOT]);
      offset = reloc_addr - plt;
      index = (offset - PLT_INITIAL_ENTRY_WORDS)/2;
      data_words = plt + PLT_DATA_START_WORDS (num_plt_entries);

      reloc_addr += 1;

      if (index < PLT_DOUBLE_SIZE)
	{
	  data_words[index] = finaladdr;
	  PPC_SYNC;
	  *reloc_addr = OPCODE_B ((PLT_LONGBRANCH_ENTRY_WORDS - (offset+1))
				  * 4);
	}
      else
	{
	  index -= (index - PLT_DOUBLE_SIZE)/2;

	  data_words[index] = finaladdr;
	  PPC_SYNC;

	  reloc_addr[1] = OPCODE_MTCTR (12);
	  MODIFIED_CODE_NOQUEUE (reloc_addr + 1);
	  PPC_SYNC;

	  reloc_addr[0] = OPCODE_LWZ (12,
				      (Elf32_Word) (data_words + index), 11);
	}
    }
  MODIFIED_CODE (reloc_addr);
  return finaladdr;
}

static void
dl_reloc_overflow (struct link_map *map,
		   const char *name,
		   Elf32_Addr *const reloc_addr,
		   const Elf32_Sym *sym,
		   const Elf32_Sym *refsym)
{
  char buffer[128];
  char *t;
  const Elf32_Sym *errsym = sym ?: refsym;
  t = stpcpy (buffer, name);
  t = stpcpy (t, " relocation at 0x00000000");
  _itoa_word ((unsigned) reloc_addr, t, 16, 0);
  if (errsym)
    {
      const char *strtab;

      strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
      t = stpcpy (t, " for symbol `");
      t = stpcpy (t, strtab + errsym->st_name);
      t = stpcpy (t, "'");
    }
  t = stpcpy (t, " out of range");
  _dl_signal_error (0, map->l_name, NULL, buffer);
}

void
__process_machine_rela (struct link_map *map,
			const Elf32_Rela *reloc,
			const Elf32_Sym *sym,
			const Elf32_Sym *refsym,
			Elf32_Addr *const reloc_addr,
			Elf32_Addr const finaladdr,
			int rinfo)
{
  switch (rinfo)
    {
    case R_PPC_NONE:
      return;

    case R_PPC_ADDR32:
    case R_PPC_GLOB_DAT:
    case R_PPC_RELATIVE:
      *reloc_addr = finaladdr;
      return;

    case R_PPC_UADDR32:
      ((char *) reloc_addr)[0] = finaladdr >> 24;
      ((char *) reloc_addr)[1] = finaladdr >> 16;
      ((char *) reloc_addr)[2] = finaladdr >> 8;
      ((char *) reloc_addr)[3] = finaladdr;
      break;

    case R_PPC_ADDR24:
      if (__builtin_expect (finaladdr > 0x01fffffc && finaladdr < 0xfe000000, 0))
	dl_reloc_overflow (map,  "R_PPC_ADDR24", reloc_addr, sym, refsym);
      *reloc_addr = (*reloc_addr & 0xfc000003) | (finaladdr & 0x3fffffc);
      break;

    case R_PPC_ADDR16:
      if (__builtin_expect (finaladdr > 0x7fff && finaladdr < 0xffff8000, 0))
	dl_reloc_overflow (map,  "R_PPC_ADDR16", reloc_addr, sym, refsym);
      *(Elf32_Half*) reloc_addr = finaladdr;
      break;

    case R_PPC_UADDR16:
      if (__builtin_expect (finaladdr > 0x7fff && finaladdr < 0xffff8000, 0))
	dl_reloc_overflow (map,  "R_PPC_UADDR16", reloc_addr, sym, refsym);
      ((char *) reloc_addr)[0] = finaladdr >> 8;
      ((char *) reloc_addr)[1] = finaladdr;
      break;

    case R_PPC_ADDR16_LO:
      *(Elf32_Half*) reloc_addr = finaladdr;
      break;

    case R_PPC_ADDR16_HI:
      *(Elf32_Half*) reloc_addr = finaladdr >> 16;
      break;

    case R_PPC_ADDR16_HA:
      *(Elf32_Half*) reloc_addr = (finaladdr + 0x8000) >> 16;
      break;

    case R_PPC_ADDR14:
    case R_PPC_ADDR14_BRTAKEN:
    case R_PPC_ADDR14_BRNTAKEN:
      if (__builtin_expect (finaladdr > 0x7fff && finaladdr < 0xffff8000, 0))
	dl_reloc_overflow (map,  "R_PPC_ADDR14", reloc_addr, sym, refsym);
      *reloc_addr = (*reloc_addr & 0xffff0003) | (finaladdr & 0xfffc);
      if (rinfo != R_PPC_ADDR14)
	*reloc_addr = ((*reloc_addr & 0xffdfffff)
		       | ((rinfo == R_PPC_ADDR14_BRTAKEN)
			  ^ (finaladdr >> 31)) << 21);
      break;

    case R_PPC_REL24:
      {
	Elf32_Sword delta = finaladdr - (Elf32_Word) reloc_addr;
	if (delta << 6 >> 6 != delta)
	  dl_reloc_overflow (map,  "R_PPC_REL24", reloc_addr, sym, refsym);
	*reloc_addr = (*reloc_addr & 0xfc000003) | (delta & 0x3fffffc);
      }
      break;

    case R_PPC_COPY:
      if (sym == NULL)
	/* This can happen in trace mode when an object could not be
	   found.  */
	return;
      if (sym->st_size > refsym->st_size
	  || (GL(dl_verbose) && sym->st_size < refsym->st_size))
	{
	  const char *strtab;

	  strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
	  _dl_error_printf ("\
%s: Symbol `%s' has different size in shared object, onsider re-linking\n",
			    rtld_progname ?: "<program name unknown>",
			    strtab + refsym->st_name);
	}
      memcpy (reloc_addr, (char *) finaladdr, MIN (sym->st_size,
						   refsym->st_size));
      return;

    case R_PPC_REL32:
      *reloc_addr = finaladdr - (Elf32_Word) reloc_addr;
      return;

    case R_PPC_JMP_SLOT:
      /* It used to be that elf_machine_fixup_plt was used here,
	 but that doesn't work when ld.so relocates itself
	 for the second time.  On the bright side, there's
         no need to worry about thread-safety here.  */
      {
	Elf32_Sword delta = finaladdr - (Elf32_Word) reloc_addr;
	if (delta << 6 >> 6 == delta)
	  *reloc_addr = OPCODE_B (delta);
	else if (finaladdr <= 0x01fffffc || finaladdr >= 0xfe000000)
	  *reloc_addr = OPCODE_BA (finaladdr);
	else
	  {
	    Elf32_Word *plt, *data_words;
	    Elf32_Word index, offset, num_plt_entries;

	    plt = (Elf32_Word *) D_PTR (map, l_info[DT_PLTGOT]);
	    offset = reloc_addr - plt;

	    if (offset < PLT_DOUBLE_SIZE*2 + PLT_INITIAL_ENTRY_WORDS)
	      {
		index = (offset - PLT_INITIAL_ENTRY_WORDS)/2;
		num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val
				   / sizeof(Elf32_Rela));
		data_words = plt + PLT_DATA_START_WORDS (num_plt_entries);
		data_words[index] = finaladdr;
		reloc_addr[0] = OPCODE_LI (11, index * 4);
		reloc_addr[1] = OPCODE_B ((PLT_LONGBRANCH_ENTRY_WORDS
					   - (offset+1))
					  * 4);
		MODIFIED_CODE_NOQUEUE (reloc_addr + 1);
	      }
	    else
	      {
		reloc_addr[0] = OPCODE_LIS_HI (12, finaladdr);
		reloc_addr[1] = OPCODE_ADDI (12, 12, finaladdr);
		reloc_addr[2] = OPCODE_MTCTR (12);
		reloc_addr[3] = OPCODE_BCTR ();
		MODIFIED_CODE_NOQUEUE (reloc_addr + 3);
	      }
	  }
      }
      break;

    default:
      _dl_reloc_bad_type (map, rinfo, 0);
      return;
    }

  MODIFIED_CODE_NOQUEUE (reloc_addr);
}