140 lines
4.6 KiB
C++
140 lines
4.6 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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#if defined(DYNAMIC_MODULES) && defined(ARM_TARGET)
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#include "backends/plugins/elf-loader.h"
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#include "backends/plugins/arm-loader.h"
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#include "common/debug.h"
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/**
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* Follow the instruction of a relocation section.
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*
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* @param DLFile SeekableReadStream of File
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* @param fileOffset Offset into the File
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* @param size Size of relocation section
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* @param relSegment Base address of relocated segment in memory (memory offset)
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*/
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bool ARMDLObject::relocate(Common::SeekableReadStream* DLFile, unsigned long offset, unsigned long size, void *relSegment) {
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Elf32_Rel *rel = 0; //relocation entry
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// Allocate memory for relocation table
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if (!(rel = (Elf32_Rel *)malloc(size))) {
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warning("elfloader: Out of memory.");
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return false;
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}
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// Read in our relocation table
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if (!DLFile->seek(offset, SEEK_SET) ||
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DLFile->read(rel, size) != size) {
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warning("elfloader: Relocation table load failed.");
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free(rel);
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return false;
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}
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// Treat each relocation entry. Loop over all of them
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int cnt = size / sizeof(*rel);
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debug(2, "elfloader: Loaded relocation table. %d entries. base address=%p", cnt, relSegment);
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int a = 0;
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unsigned int relocation = 0;
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// Loop over relocation entries
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for (int i = 0; i < cnt; i++) {
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// Get the symbol this relocation entry is referring to
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Elf32_Sym *sym = (Elf32_Sym *)(_symtab) + (REL_INDEX(rel[i].r_info));
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// Get the target instruction in the code
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unsigned int *target = (unsigned int *)((char *)relSegment + rel[i].r_offset);
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unsigned int origTarget = *target; //Save for debugging
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// Act differently based on the type of relocation
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switch (REL_TYPE(rel[i].r_info)) {
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case R_ARM_ABS32:
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if (sym->st_shndx < SHN_LOPROC) { // Only shift for plugin section.
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a = *target; // Get full 32 bits of addend
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relocation = a + (Elf32_Addr)_segment; // Shift by main offset
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*target = relocation;
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debug(8, "elfloader: R_ARM_ABS32: i=%d, a=%x, origTarget=%x, target=%x", i, a, origTarget, *target);
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}
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break;
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case R_ARM_THM_CALL:
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debug(8, "elfloader: R_ARM_THM_CALL: PC-relative jump, ld takes care of necessary relocation work for us.");
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break;
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case R_ARM_CALL:
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debug(8, "elfloader: R_ARM_CALL: PC-relative jump, ld takes care of necessary relocation work for us.");
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break;
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case R_ARM_JUMP24:
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debug(8, "elfloader: R_ARM_JUMP24: PC-relative jump, ld takes care of all relocation work for us.");
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break;
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case R_ARM_V4BX:
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debug(8, "elfloader: R_ARM_V4BX: No relocation calculation necessary.");
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break;
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default:
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warning("elfloader: Unknown relocation type %d.", REL_TYPE(rel[i].r_info));
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free(rel);
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return false;
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}
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}
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free(rel);
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return true;
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}
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bool ARMDLObject::relocateRels(Common::SeekableReadStream* DLFile, Elf32_Ehdr *ehdr, Elf32_Shdr *shdr) {
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// Loop over sections, finding relocation sections
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for (int i = 0; i < ehdr->e_shnum; i++) {
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Elf32_Shdr *curShdr = &(shdr[i]);
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if ((curShdr->sh_type == SHT_REL || curShdr->sh_type == SHT_RELA) && // Check for a relocation section
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curShdr->sh_entsize == sizeof(Elf32_Rel) && // Check for proper relocation size
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(int)curShdr->sh_link == _symtab_sect && // Check that the sh_link connects to our symbol table
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curShdr->sh_info < ehdr->e_shnum && // Check that the relocated section exists
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(shdr[curShdr->sh_info].sh_flags & SHF_ALLOC)) { // Check if relocated section resides in memory
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if (curShdr->sh_type == SHT_RELA) {
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warning("elfloader: RELA entries not supported yet!");
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return false;
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}
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if (!relocate(DLFile, curShdr->sh_offset, curShdr->sh_size, _segment))
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return false;
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}
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}
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return true;
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}
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#endif /* defined(DYNAMIC_MODULES) && defined(ARM_TARGET) */
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