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ppc-loader.cpp

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

#include "common/scummsys.h"

#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(PPC_TARGET)

#include "backends/plugins/elf/elf-loader.h"
#include "backends/plugins/elf/ppc-loader.h"

#include "common/debug.h"

bool PPCDLObject::relocate(Elf32_Off offset, Elf32_Word size, byte *relSegment) {
      Elf32_Rela *rel = NULL;

      if (!(rel = (Elf32_Rela *)malloc(size))) {
            warning("elfloader: Out of memory.");
            return false;
      }

      if (!_file->seek(offset, SEEK_SET) || _file->read(rel, size) != size) {
            warning("elfloader: Relocation table load failed.");
            free(rel);
            return false;
      }

      uint32 cnt = size / sizeof(*rel);

      debug(2, "elfloader: Loaded relocation table. %d entries. base address=%p", cnt, relSegment);

      uint32 *src;
      uint32 value;

      for (uint32 i = 0; i < cnt; i++) {
            // Get the symbol this relocation entry is referring to
            Elf32_Sym *sym = _symtab + (REL_INDEX(rel[i].r_info));

            // Get the target instruction in the code
            src = (uint32 *)((char *)relSegment + rel[i].r_offset - _segmentVMA);
            value = sym->st_value + rel[i].r_addend;

            //debug(8, "elfloader: i=%05d %p +0x%04x: (0x%08x) 0x%08x ", i, src, rel[i].r_addend, sym->st_value, *src);

            switch (REL_TYPE(rel[i].r_info)) {
            case R_PPC_ADDR32:
                  *src = value;
                  debug(8, "elfloader: R_PPC_ADDR32 -> 0x%08x", *src);
                  break;
            case R_PPC_ADDR16_LO:
                  *(uint16 *)src = value;
                  debug(8, "elfloader: R_PPC_ADDR16_LO -> 0x%08x", *src);
                  break;
            case R_PPC_ADDR16_HI:
                  *(uint16 *)src = value >> 16;
                  debug(8, "elfloader: R_PPC_ADDR16_HA -> 0x%08x", *src);
                  break;
            case R_PPC_ADDR16_HA:
                  *(uint16 *)src = (value + 0x8000) >> 16;
                  debug(8, "elfloader: R_PPC_ADDR16_HA -> 0x%08x", *src);
                  break;
            case R_PPC_REL24:
                  *src = (*src & ~0x03fffffc) | ((value - (uint32)src) & 0x03fffffc);
                  debug(8, "elfloader: R_PPC_REL24 -> 0x%08x", *src);
                  break;
            case R_PPC_REL32:
                  *src = value - (uint32)src;
                  debug(8, "elfloader: R_PPC_REL32 -> 0x%08x", *src);
                  break;
            default:
                  warning("elfloader: Unknown relocation type %d", REL_TYPE(rel[i].r_info));
                  free(rel);
                  return false;
            }
      }

      free(rel);
      return true;
}

bool PPCDLObject::relocateRels(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr) {
      for (uint32 i = 0; i < ehdr->e_shnum; i++) {
            Elf32_Shdr *curShdr = &(shdr[i]);

            if ((curShdr->sh_type == SHT_REL) &&
                        curShdr->sh_entsize == sizeof(Elf32_Rel) &&
                        int32(curShdr->sh_link) == _symtab_sect &&
                        curShdr->sh_info < ehdr->e_shnum &&
                        (shdr[curShdr->sh_info].sh_flags & SHF_ALLOC)) {
                  warning("elfloader: REL entries not supported!");
                  return false;
            }

            if ((curShdr->sh_type == SHT_RELA) &&
                        curShdr->sh_entsize == sizeof(Elf32_Rela) &&
                        int32(curShdr->sh_link) == _symtab_sect &&
                        curShdr->sh_info < ehdr->e_shnum &&
                        (shdr[curShdr->sh_info].sh_flags & SHF_ALLOC)) {
                  if (!relocate(curShdr->sh_offset, curShdr->sh_size, _segment))
                        return false;
            }
      }

      return true;
}

#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(PPC_TARGET) */


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