diff options
Diffstat (limited to 'backends/plugins/arm-loader.cpp')
| -rw-r--r-- | backends/plugins/arm-loader.cpp | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/backends/plugins/arm-loader.cpp b/backends/plugins/arm-loader.cpp new file mode 100644 index 0000000000..7e8269220b --- /dev/null +++ b/backends/plugins/arm-loader.cpp @@ -0,0 +1,169 @@ +/* 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. + * + * $URL$ + * $Id$ + * + */ + +#if defined(DYNAMIC_MODULES) && defined(ARM_TARGET) + +#include "backends/fs/ds/ds-fs.h" +#include "elf-loader.h" +#include "dsmain.h" +#include "arm-loader.h" + +#define __DEBUG_PLUGINS__ + +#ifdef __DEBUG_PLUGINS__ +#define DBG(x,...) consolePrintf(x, ## __VA_ARGS__) +#else +#define DBG(x,...) +#endif + +#define seterror(x,...) consolePrintf(x, ## __VA_ARGS__) + +/** + * Follow the instruction of a relocation section. + * + * @param DLFile SeekableReadStream of File + * @param offset Offset into the File + * @param size Size of relocation section + * + */ +bool ARMDLObject::relocate(Common::SeekableReadStream* DLFile, unsigned long offset, unsigned long size, void *relSegment) { + Elf32_Rel *rel = NULL; //relocation entry + + // Allocate memory for relocation table + if (!(rel = (Elf32_Rel *)malloc(size))) { + seterror("Out of memory."); + return false; + } + + // Read in our relocation table + if (DLFile->seek(offset, SEEK_SET) < 0 || + DLFile->read(rel, size) != (ssize_t)size) { + seterror("Relocation table load failed."); + free(rel); + return false; + } + + // Treat each relocation entry. Loop over all of them + int cnt = size / sizeof(*rel); + + DBG("Loaded relocation table. %d entries. base address=%p\n", cnt, relSegment); + + int a = 0; + unsigned int relocation = 0; + + // Loop over relocation entries + for (int i = 0; i < cnt; i++) { + + // Get the symbol this relocation entry is referring to + Elf32_Sym *sym = (Elf32_Sym *)(_symtab) + (REL_INDEX(rel[i].r_info)); + + // Get the target instruction in the code + unsigned int *target = (unsigned int *)((char *)relSegment + rel[i].r_offset); + + unsigned int origTarget = *target; //Save for debugging + + // Act differently based on the type of relocation + switch (REL_TYPE(rel[i].r_info)) { + + case R_ARM_ABS32: + if (sym->st_shndx < SHN_LOPROC) { // Only shift for plugin section. + a = *target; // Get full 32 bits of addend + relocation = a + (Elf32_Addr)_segment; // Shift by main offset + + *target = relocation; + + DBG("R_ARM_ABS32: i=%d, a=%x, origTarget=%x, target=%x\n", i, a, origTarget, *target); + } + break; + + case R_ARM_THM_CALL: + DBG("R_ARM_THM_CALL: PC-relative jump, ld takes care of necessary relocation work for us.\n"); + break; + + case R_ARM_CALL: + DBG("R_ARM_CALL: PC-relative jump, ld takes care of necessary relocation work for us.\n"); + break; + + case R_ARM_JUMP24: + DBG("R_ARM_JUMP24: PC-relative jump, ld takes care of all relocation work for us.\n"); + break; + + case R_ARM_TARGET1: + if (sym->st_shndx < SHN_LOPROC) { // Only shift for plugin section. + a = *target; // Get full 32 bits of addend + relocation = a + (Elf32_Addr)_segment; // Shift by main offset + + *target = relocation; + + DBG("R_ARM_TARGET1: i=%d, a=%x, origTarget=%x, target=%x\n", i, a, origTarget, *target); + DBG("Make sure --target1-abs is a flag to LD!\n"); + } + break; + + case R_ARM_V4BX: + DBG("R_ARM_V4BX: No relocation calculation necessary.\n"); + break; + + default: + seterror("Unknown relocation type %d.", REL_TYPE(rel[i].r_info)); + free(rel); + return false; + } + + } + + free(rel); + return true; +} + +bool ARMDLObject::relocateRels(Common::SeekableReadStream* DLFile, Elf32_Ehdr *ehdr, Elf32_Shdr *shdr) { + + // Loop over sections, finding relocation sections + for (int i = 0; i < ehdr->e_shnum; i++) { + + Elf32_Shdr *curShdr = &(shdr[i]); + + if ((curShdr->sh_type == SHT_REL || curShdr->sh_type == SHT_RELA) && // Check for a relocation section + curShdr->sh_entsize == sizeof(Elf32_Rel) && // Check for proper relocation size + (int)curShdr->sh_link == _symtab_sect && // Check that the sh_link connects to our symbol table + curShdr->sh_info < ehdr->e_shnum && // Check that the relocated section exists + (shdr[curShdr->sh_info].sh_flags & SHF_ALLOC)) { // Check if relocated section resides in memory + + if (curShdr->sh_type == SHT_RELA) { + seterror("RELA entries not supported yet!\n"); + return false; + } + + if (!relocate(DLFile, curShdr->sh_offset, curShdr->sh_size, _segment)) { + return false; + } + + } + } + + return true; +} + +#endif /* defined(DYNAMIC_MODULES) && defined(ARM_TARGET) */ |