Initial commit

backends/plugins/elf/arm-loader.cpp

@@ -0,0 +1,137 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(ARM_TARGET)
+
+#include "backends/plugins/elf/arm-loader.h"
+
+#include "common/debug.h"
+
+bool ARMDLObject::relocate(Elf32_Off offset, Elf32_Word size, byte *relSegment) {
+	Elf32_Rel *rel = 0; //relocation entry
+
+	// Allocate memory for relocation table
+	if (!(rel = (Elf32_Rel *)malloc(size))) {
+		warning("elfloader: Could not allocate %d bytes for the relocation table", size);
+		return false;
+	}
+
+	// Read in our relocation table
+	if (!_file->seek(offset, SEEK_SET) || _file->read(rel, size) != size) {
+		warning("elfloader: Relocation table load failed.");
+		free(rel);
+		return false;
+	}
+
+	// Treat each relocation entry. Loop over all of them
+	uint32 cnt = size / sizeof(*rel);
+
+	debug(2, "elfloader: Loaded relocation table. %d entries. base address=%p", cnt, relSegment);
+
+	int32 a = 0;
+	uint32 relocation = 0;
+
+	// Loop over relocation entries
+	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.
+		uint32 *target = (uint32 *)((byte *)relSegment + rel[i].r_offset - _segmentVMA);
+
+//		uint32 origTarget = *target;	//Save for debugging
+
+		// Act differently based on the type of relocation
+		switch (REL_TYPE(rel[i].r_info)) {
+		case R_ARM_NONE:
+//		        debug(8, "elfloader: R_ARM_NONE: No relocation.");
+			break;
+		case R_ARM_ABS32:
+		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 - _segmentVMA + Elf32_Addr(_segment);	// Shift by main offset
+
+				*target = relocation;
+
+//				debug(8, "elfloader: R_ARM_ABS32: i=%d, a=%x, origTarget=%x, target=%x", i, a, origTarget, *target);
+			}
+			break;
+
+		// Note: PREL31 often points to a different section, so if we ever load in several segments, this needs to be adjusted
+		case R_ARM_PREL31:
+//		        debug(8, "elfloader: R_ARM_PREL31: PC-relative reference, ld takes care of necessary relocation work for us.");
+			break;
+
+		case R_ARM_PC24:
+//			debug(8, "elfloader: R_ARM_PC24: PC-relative jump, ld takes care of necessary relocation work for us.");
+			break;
+
+		case R_ARM_THM_CALL:
+//			debug(8, "elfloader: R_ARM_THM_CALL: PC-relative jump, ld takes care of necessary relocation work for us.");
+			break;
+
+		case R_ARM_CALL:
+		case R_ARM_JUMP24:
+//			debug(8, "elfloader: R_ARM_CALL/R_ARM_JUMP24: PC-relative jump, ld takes care of necessary relocation work for us.");
+			break;
+		case R_ARM_V4BX:
+//			debug(8, "elfloader: R_ARM_V4BX: No relocation calculation necessary.");
+			break;
+
+		default:
+			warning("elfloader: Unknown relocation type %d.", REL_TYPE(rel[i].r_info));
+			free(rel);
+			return false;
+		}
+	}
+
+	free(rel);
+	return true;
+}
+
+bool ARMDLObject::relocateRels(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr) {
+	// Loop over sections, finding relocation sections
+	for (uint32 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
+				int32(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) {
+				warning("elfloader: RELA entries not supported yet!");
+				return false;
+			}
+
+			if (!relocate(curShdr->sh_offset, curShdr->sh_size, _segment))
+				return false;
+		}
+	}
+
+	return true;
+}
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(ARM_TARGET) */

backends/plugins/elf/arm-loader.h

@@ -0,0 +1,39 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef BACKENDS_PLUGINS_ARM_LOADER_H
+#define BACKENDS_PLUGINS_ARM_LOADER_H
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(ARM_TARGET)
+
+#include "backends/plugins/elf/elf-loader.h"
+
+class ARMDLObject : public DLObject {
+protected:
+	virtual bool relocate(Elf32_Off offset, Elf32_Word size, byte *relSegment);
+	virtual bool relocateRels(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr);
+};
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(ARM_TARGET) */
+
+#endif /* BACKENDS_PLUGINS_ARM_LOADER_H */

backends/plugins/elf/elf-loader.cpp

@@ -0,0 +1,510 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+#include "backends/plugins/elf/elf-loader.h"
+#include "backends/plugins/elf/memory-manager.h"
+
+#include "common/debug.h"
+#include "common/file.h"
+#include "common/fs.h"
+#include "common/ptr.h"
+
+#include <malloc.h>	// for memalign()
+
+DLObject::DLObject() :
+	_file(0),
+	_segment(0),
+	_symtab(0),
+	_strtab(0),
+	_segmentSize(0),
+	_segmentOffset(0),
+	_segmentVMA(0),
+	_symbol_cnt(0),
+	_symtab_sect(-1),
+	_dtors_start(0),
+	_dtors_end(0) {
+}
+
+DLObject::~DLObject() {
+	discardSymtab();
+	discardSegment();
+}
+
+// Expel the symbol table from memory
+void DLObject::discardSymtab() {
+	free(_symtab);
+	_symtab = 0;
+
+	free(_strtab);
+	_strtab = 0;
+
+	_symbol_cnt = 0;
+}
+
+void DLObject::discardSegment() {
+	if (_segment) {
+		// Restore default protection before returning memory
+		protectMemory(_segment, _segmentSize, PF_R | PF_W);
+		deallocateMemory(_segment, _segmentSize);
+	}
+
+	_segment = 0;
+	_segmentSize = 0;
+	_segmentOffset = 0;
+	_segmentVMA = 0;
+}
+
+// Unload all objects from memory
+void DLObject::unload() {
+	discardSymtab();
+	discardSegment();
+}
+
+bool DLObject::readElfHeader(Elf32_Ehdr *ehdr) {
+	assert(_file);
+
+	// Start reading the elf header. Check for errors and magic
+	if (_file->read(ehdr, sizeof(*ehdr)) != sizeof(*ehdr) ||
+			memcmp(ehdr->e_ident, ELFMAG, SELFMAG)) {
+		warning("elfloader: No ELF file.");
+		return false;
+	}
+
+	if (ehdr->e_ident[EI_CLASS] != ELFCLASS32) {
+		warning("elfloader: Wrong ELF file class.");
+		return false;
+	}
+
+	if (ehdr->e_ident[EI_DATA] !=
+#ifdef SCUMM_BIG_ENDIAN
+			ELFDATA2MSB
+#else
+			ELFDATA2LSB
+#endif
+			) {
+		warning("elfloader: Wrong ELF file endianess.");
+		return false;
+	}
+
+	if (ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
+		warning("elfloader: Wrong ELF file version.");
+		return false;
+	}
+
+	if (ehdr->e_type != ET_EXEC) {
+		warning("elfloader: No executable ELF file.");
+		return false;
+	}
+
+	if (ehdr->e_machine !=
+#ifdef ARM_TARGET
+			EM_ARM
+#endif
+#ifdef MIPS_TARGET
+			EM_MIPS
+#endif
+#ifdef PPC_TARGET
+			EM_PPC
+#endif
+			) {
+		warning("elfloader: Wrong ELF file architecture.");
+		return false;
+	}
+
+	if (ehdr->e_phentsize < sizeof(Elf32_Phdr)	 ||			// Check for size of program header
+			ehdr->e_shentsize != sizeof(Elf32_Shdr)) {		// Check for size of section header
+		warning("elfloader: Invalid ELF structure sizes.");
+		return false;
+	}
+
+	debug(2, "elfloader: phoff = %d, phentsz = %d, phnum = %d",
+			ehdr->e_phoff, ehdr->e_phentsize, ehdr->e_phnum);
+
+	return true;
+}
+
+bool DLObject::readProgramHeaders(Elf32_Ehdr *ehdr, Elf32_Phdr *phdr, Elf32_Half num) {
+	assert(_file);
+
+	// Read program header
+	if (!_file->seek(ehdr->e_phoff + sizeof(*phdr) * num, SEEK_SET) ||
+			_file->read(phdr, sizeof(*phdr)) != sizeof(*phdr)) {
+		warning("elfloader: Program header load failed.");
+		return false;
+	}
+
+	// Check program header values
+	if (phdr->p_type != PT_LOAD  || phdr->p_filesz > phdr->p_memsz) {
+		warning("elfloader: Invalid program header %x", phdr->p_type);
+		return false;
+	}
+
+	debug(2, "elfloader: offs = %x, filesz = %x, memsz = %x, align = %x",
+			phdr->p_offset, phdr->p_filesz, phdr->p_memsz, phdr->p_align);
+
+	return true;
+}
+
+bool DLObject::loadSegment(Elf32_Phdr *phdr) {
+	_segment = (byte *)allocateMemory(phdr->p_align, phdr->p_memsz);
+
+	if (!_segment) {
+		warning("elfloader: Could not allocate %d bytes for the segment", phdr->p_memsz);
+		return false;
+	}
+
+	debug(2, "elfloader: Allocated segment @ %p", _segment);
+
+	// Get offset to load segment into
+	_segmentSize = phdr->p_memsz;
+	_segmentVMA = phdr->p_vaddr;
+
+	// Set .bss segment to 0 if necessary
+	if (phdr->p_memsz > phdr->p_filesz) {
+		debug(2, "elfloader: Setting %p to %p to 0 for bss",
+				_segment + phdr->p_filesz, _segment + phdr->p_memsz);
+		memset(_segment + phdr->p_filesz, 0, phdr->p_memsz - phdr->p_filesz);
+	}
+
+	debug(2, "elfloader: Reading the segment into memory");
+
+	// Read the segment into memory
+	if (!_file->seek(phdr->p_offset, SEEK_SET) ||
+			_file->read(_segment, phdr->p_filesz) != phdr->p_filesz) {
+		warning("elfloader: Segment load failed.");
+		return false;
+	}
+
+	debug(2, "elfloader: Segment has been read into memory");
+
+	return true;
+}
+
+Elf32_Shdr * DLObject::loadSectionHeaders(Elf32_Ehdr *ehdr) {
+	assert(_file);
+
+	Elf32_Shdr *shdr = 0;
+
+	// Allocate memory for section headers
+	if (!(shdr = (Elf32_Shdr *)malloc(ehdr->e_shnum * sizeof(*shdr)))) {
+		warning("elfloader: Could not allocate %zu bytes for the section headers", ehdr->e_shnum * sizeof(*shdr));
+		return 0;
+	}
+
+	// Read from file into section headers
+	if (!_file->seek(ehdr->e_shoff, SEEK_SET) ||
+			_file->read(shdr, ehdr->e_shnum * sizeof(*shdr)) !=
+			ehdr->e_shnum * sizeof(*shdr)) {
+		warning("elfloader: Section headers load failed.");
+		free(shdr);
+		return 0;
+	}
+
+	return shdr;
+}
+
+int DLObject::findSymbolTableSection(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr) {
+	int SymbolTableSection = -1;
+
+	// Loop over sections, looking for symbol table linked to a string table
+	for (uint32 i = 0; i < ehdr->e_shnum; i++) {
+		if (shdr[i].sh_type == SHT_SYMTAB &&
+				shdr[i].sh_entsize == sizeof(Elf32_Sym) &&
+				shdr[i].sh_link < ehdr->e_shnum &&
+				shdr[shdr[i].sh_link].sh_type == SHT_STRTAB) {
+			SymbolTableSection = i;
+			break;
+		}
+	}
+
+	return SymbolTableSection;
+}
+
+int DLObject::loadSymbolTable(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr) {
+	assert(_file);
+
+	_symtab_sect = findSymbolTableSection(ehdr, shdr);
+
+	// Check for no symbol table
+	if (_symtab_sect < 0) {
+		warning("elfloader: No symbol table.");
+		return -1;
+	}
+
+	debug(2, "elfloader: Symbol section at section %d, size %x",
+			_symtab_sect, shdr[_symtab_sect].sh_size);
+
+	// Allocate memory for symbol table
+	if (!(_symtab = (Elf32_Sym *)malloc(shdr[_symtab_sect].sh_size))) {
+		warning("elfloader: Could not allocate %d bytes for the symbol table", shdr[_symtab_sect].sh_size);
+		return -1;
+	}
+
+	// Read symbol table into memory
+	if (!_file->seek(shdr[_symtab_sect].sh_offset, SEEK_SET) ||
+			_file->read(_symtab, shdr[_symtab_sect].sh_size) !=
+			shdr[_symtab_sect].sh_size) {
+		warning("elfloader: Symbol table load failed.");
+		free(_symtab);
+		_symtab = 0;
+		return -1;
+	}
+
+	// Set number of symbols
+	_symbol_cnt = shdr[_symtab_sect].sh_size / sizeof(Elf32_Sym);
+	debug(2, "elfloader: Loaded %d symbols.", _symbol_cnt);
+
+	return _symtab_sect;
+}
+
+bool DLObject::loadStringTable(Elf32_Shdr *shdr) {
+	assert(_file);
+
+	uint32 string_sect = shdr[_symtab_sect].sh_link;
+
+	// Allocate memory for string table
+	if (!(_strtab = (char *)malloc(shdr[string_sect].sh_size))) {
+		warning("elfloader: Could not allocate %d bytes for the string table", shdr[string_sect].sh_size);
+		return false;
+	}
+
+	// Read string table into memory
+	if (!_file->seek(shdr[string_sect].sh_offset, SEEK_SET) ||
+			_file->read(_strtab, shdr[string_sect].sh_size) !=
+			shdr[string_sect].sh_size) {
+		warning("elfloader: Symbol table strings load failed.");
+		free(_strtab);
+		_strtab = 0;
+		return false;
+	}
+
+	return true;
+}
+
+void DLObject::relocateSymbols(ptrdiff_t offset) {
+	// Loop over symbols, add relocation offset
+	Elf32_Sym *s = _symtab;
+
+	for (uint32 c = _symbol_cnt; c--; s++) {
+		// Make sure we don't relocate special valued symbols
+		if (s->st_shndx < SHN_LOPROC) {
+			if (s->st_value < _segmentVMA)
+				s->st_value = _segmentVMA;	// deal with symbols referring to sections, which start before the VMA
+
+			s->st_value += offset;
+
+			if (s->st_value < Elf32_Addr(_segment) ||
+					s->st_value > Elf32_Addr(_segment) + _segmentSize)
+				warning("elfloader: Symbol out of bounds! st_value = %x", s->st_value);
+		}
+	}
+}
+
+// Track the size of the plugin through memory manager without loading
+// the plugin into memory.
+//
+void DLObject::trackSize(const Common::Path &path) {
+	_file = Common::FSNode(path).createReadStream();
+
+	if (!_file) {
+		warning("elfloader: File %s not found.", path.toString(Common::Path::kNativeSeparator).c_str());
+		return;
+	}
+
+	Elf32_Ehdr ehdr;
+	Elf32_Phdr phdr;
+
+	if (!readElfHeader(&ehdr)) {
+		delete _file;
+		_file = 0;
+		return;
+	}
+
+	ELFMemMan.trackPlugin(true);	// begin tracking the plugin size
+
+	// Load the segments
+	for (uint32 i = 0; i < ehdr.e_phnum; i++) {
+		debug(2, "elfloader: Loading segment %d", i);
+
+		if (!readProgramHeaders(&ehdr, &phdr, i)) {
+			delete _file;
+			_file = 0;
+			return;
+		}
+
+		if (phdr.p_flags & PF_X) {	// check for executable, allocated segment
+			ELFMemMan.trackAlloc(phdr.p_align, phdr.p_memsz);
+		}
+	}
+
+	ELFMemMan.trackPlugin(false);	// we're done tracking the plugin size
+
+	delete _file;
+	_file = 0;
+	// No need to track the symbol table sizes -- they get discarded
+}
+
+bool DLObject::load() {
+	Elf32_Ehdr ehdr;
+	Elf32_Phdr phdr;
+
+	if (readElfHeader(&ehdr) == false)
+		return false;
+
+	//Load the segments
+	for (uint32 i = 0; i < ehdr.e_phnum; i++) {
+		debug(2, "elfloader: Loading segment %d", i);
+
+		if (readProgramHeaders(&ehdr, &phdr, i) == false)
+			return false;
+
+		if (!loadSegment(&phdr))
+			return false;
+	}
+
+	Elf32_Shdr *shdr = loadSectionHeaders(&ehdr);
+	if (!shdr)
+		return false;
+
+	_symtab_sect = loadSymbolTable(&ehdr, shdr);
+	if (_symtab_sect < 0) {
+		free(shdr);
+		return false;
+	}
+
+	if (!loadStringTable(shdr)) {
+		free(shdr);
+		return false;
+	}
+
+	// Offset by our segment allocated address
+	// must use _segmentVMA here for multiple segments (MIPS)
+	_segmentOffset = ptrdiff_t(_segment) - _segmentVMA;
+	relocateSymbols(_segmentOffset);
+
+	if (!relocateRels(&ehdr, shdr)) {
+		free(shdr);
+		return false;
+	}
+
+	protectMemory(_segment, _segmentSize, phdr.p_flags);
+
+	return true;
+}
+
+bool DLObject::open(const Common::Path &path) {
+	Common::String pathS(path.toString(Common::Path::kNativeSeparator));
+
+	void *ctors_start, *ctors_end;
+
+	debug(2, "elfloader: open(\"%s\")", pathS.c_str());
+
+	_file = Common::FSNode(path).createReadStream();
+
+	if (!_file) {
+		warning("elfloader: File %s not found.", pathS.c_str());
+		return false;
+	}
+
+	debug(2, "elfloader: %s found!", pathS.c_str());
+
+	/*Try to load and relocate*/
+	if (!load()) {
+		unload();
+		return false;
+	}
+
+	debug(2, "elfloader: Loaded!");
+
+	delete _file;
+	_file = 0;
+
+	flushDataCache(_segment, _segmentSize);
+
+	ctors_start = symbol("___plugin_ctors");
+	ctors_end = symbol("___plugin_ctors_end");
+	_dtors_start = symbol("___plugin_dtors");
+	_dtors_end = symbol("___plugin_dtors_end");
+
+	if (!ctors_start || !ctors_end || !_dtors_start || !_dtors_end) {
+		warning("elfloader: Missing ctors/dtors.");
+		_dtors_start = _dtors_end = 0;
+		unload();
+		return false;
+	}
+
+	debug(2, "elfloader: Calling constructors.");
+	for (void (**f)(void) = (void (**)(void))ctors_start; f != ctors_end; f++)
+		(**f)();
+
+	debug(2, "elfloader: %s opened ok.", pathS.c_str());
+
+	return true;
+}
+
+bool DLObject::close() {
+	if (_dtors_start && _dtors_end)
+		for (void (**f)(void) = (void (**)(void))_dtors_start; f != _dtors_end; f++)
+			(**f)();
+
+	_dtors_start = _dtors_end = 0;
+	unload();
+	return true;
+}
+
+void *DLObject::symbol(const char *name) {
+	debug(2, "elfloader: Symbol(\"%s\")", name);
+
+	if (!_symtab || !_strtab || _symbol_cnt < 1) {
+		warning("elfloader: No symbol table loaded.");
+		return 0;
+	}
+
+	Elf32_Sym *s = _symtab;
+
+	for (uint32 c = _symbol_cnt; c--; s++)
+		// We can only import symbols that are global or weak in the plugin
+		if ((SYM_BIND(s->st_info) == STB_GLOBAL ||
+				SYM_BIND(s->st_info) == STB_WEAK) &&
+				!strcmp(name, _strtab + s->st_name)) {
+			// We found the symbol
+			debug(2, "elfloader: => 0x%08x", s->st_value);
+			return (void *)s->st_value;
+		}
+
+	// We didn't find the symbol
+	warning("elfloader: Symbol \"%s\" not found.", name);
+	return 0;
+}
+
+void *DLObject::allocateMemory(uint32 align, uint32 size) {
+	return ELFMemMan.pluginAllocate(align, size);
+}
+
+void DLObject::deallocateMemory(void *ptr, uint32 size) {
+	ELFMemMan.pluginDeallocate(ptr);
+}
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) */

backends/plugins/elf/elf-loader.h

@@ -0,0 +1,107 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef BACKENDS_PLUGINS_ELF_LOADER_H
+#define BACKENDS_PLUGINS_ELF_LOADER_H
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+#include <stddef.h>
+
+#include "backends/plugins/elf/elf32.h"
+#include "backends/plugins/dynamic-plugin.h"
+
+#include "common/stream.h"
+
+/**
+ * DLObject
+ *
+ * Class that most directly handles operations on a plugin file
+ * (opening it for reading, loading/unloading it in memory, finding a specific symbol in the file, etc.)
+ * Subclasses have the same functionality, but implementations specific to different processors/platforms.
+ */
+class DLObject {
+protected:
+	Common::SeekableReadStream *_file;
+
+	byte *_segment;
+	Elf32_Sym *_symtab;
+	char *_strtab;
+
+	uint32 _segmentSize;
+	ptrdiff_t _segmentOffset;
+	uint32 _segmentVMA;
+
+	uint32 _symbol_cnt;
+	int32 _symtab_sect;
+	void *_dtors_start, *_dtors_end;
+
+	virtual void unload();
+	bool load();
+
+	bool readElfHeader(Elf32_Ehdr *ehdr);
+	bool readProgramHeaders(Elf32_Ehdr *ehdr, Elf32_Phdr *phdr, Elf32_Half num);
+	virtual bool loadSegment(Elf32_Phdr *phdr);
+	Elf32_Shdr *loadSectionHeaders(Elf32_Ehdr *ehdr);
+	int findSymbolTableSection(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr);
+	int loadSymbolTable(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr);
+	bool loadStringTable(Elf32_Shdr *shdr);
+	virtual void relocateSymbols(ptrdiff_t offset);
+	void discardSegment();
+
+	// architecture specific
+
+	/**
+	 * Follow the instruction of a relocation section.
+	 *
+	 * @param fileOffset	Offset into the File
+	 * @param size			Size of relocation section
+	 * @param relSegment	Base address of relocated segment in memory (memory offset)
+	 */
+	virtual bool relocate(Elf32_Off offset, Elf32_Word size, byte *relSegment) = 0;
+	virtual bool relocateRels(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr) = 0;
+
+	// platform specific
+	virtual void flushDataCache(void *ptr, uint32 len) const = 0;
+	virtual void *allocateMemory(uint32 align, uint32 size);
+	virtual void deallocateMemory(void *ptr, uint32 size);
+	virtual void protectMemory(void *ptr, uint32 len, int prot) const {};
+
+public:
+	DLObject();
+	virtual ~DLObject();
+
+	/**
+	 * Test the size of the plugin in memory using the memory manager.
+	 * @param path			Path of file
+	 */
+	void trackSize(const Common::Path &path);
+	bool open(const Common::Path &path);
+	bool close();
+	void *symbol(const char *name);
+	void discardSymtab();
+};
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) */
+
+#endif /* BACKENDS_PLUGINS_ELF_LOADER_H */

backends/plugins/elf/elf-provider.cpp

@@ -0,0 +1,210 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+#ifdef ELF_LOADER_CXA_ATEXIT
+#include <cxxabi.h>
+#endif
+
+#include "backends/plugins/elf/elf-provider.h"
+#include "backends/plugins/dynamic-plugin.h"
+#include "backends/plugins/elf/memory-manager.h"
+
+#include "common/debug.h"
+#include "common/fs.h"
+
+/* Note about ELF_LOADER_CXA_ATEXIT:
+ *
+ * consider the code:
+ *
+ * class Foobar {
+ *   const char *work() {
+ *     static String foo = "bar";
+ *     return s.c_str();
+ *   }
+ * }
+ *
+ * When instantiating Foobar and calling work() for the first time the String
+ * foo will be constructed. GCC automatically registers its destruction via
+ * either atexit() or __cxa_atexit(). Only the latter will add information
+ * about which DSO did the construction (Using &__dso_handle).
+ *
+ * __cxa_atexit allows plugins to reference C++ ABI symbols in the main
+ * executable without code duplication (No need to link the plugin against
+ * libstdc++), since we can distinguish which registered exit functions belong
+ * to a specific DSO. When unloading a plugin, we just use the C++ ABI call
+ * __cxa_finalize(&__dso_handle) to call all destructors of only that DSO.
+ *
+ * Prerequisites:
+ * - The used libc needs to support __cxa_atexit
+ * - -fuse-cxa-atexit in CXXFLAGS
+ * - Every plugin needs its own hidden __dso_handle symbol
+ *   This is automatically done via REGISTER_PLUGIN_DYNAMIC, see base/plugins.h
+ *
+ * When __cxa_atexit can not be used, each plugin needs to link against
+ * libstdc++ to embed its own set of C++ ABI symbols. When not doing so,
+ * registered destructors of already unloaded plugins will crash the
+ * application upon returning from main().
+ *
+ * See "3.3.5 DSO Object Destruction API" of the C++ ABI
+ */
+
+DynamicPlugin::VoidFunc ELFPlugin::findSymbol(const char *symbol) {
+	void *func = 0;
+
+	if (_dlHandle)
+		func = _dlHandle->symbol(symbol);
+
+	if (!func) {
+		if (!_dlHandle)
+			warning("elfloader: Failed loading symbol '%s' from plugin '%s' (Handle is NULL)", symbol, _filename.toString(Common::Path::kNativeSeparator).c_str());
+		else
+			warning("elfloader: Failed loading symbol '%s' from plugin '%s'", symbol, _filename.toString(Common::Path::kNativeSeparator).c_str());
+	}
+
+	// FIXME HACK: This is a HACK to circumvent a clash between the ISO C++
+	// standard and POSIX: ISO C++ disallows casting between function pointers
+	// and data pointers, but dlsym always returns a void pointer. For details,
+	// see e.g. <https://web.archive.org/web/20061205092618/http://www.trilithium.com/johan/2004/12/problem-with-dlsym/>.
+	assert(sizeof(VoidFunc) == sizeof(func));
+	VoidFunc tmp;
+	memcpy(&tmp, &func, sizeof(VoidFunc));
+	return tmp;
+}
+
+ /**
+  * Test the size of the plugin.
+  */
+void ELFPlugin::trackSize() {
+	// All we need to do is create our object, track its size, then delete it
+	DLObject *obj = makeDLObject();
+
+	obj->trackSize(_filename);
+	delete obj;
+}
+
+bool ELFPlugin::loadPlugin() {
+	assert(!_dlHandle);
+
+	DLObject *obj = makeDLObject();
+	if (obj->open(_filename)) {
+		_dlHandle = obj;
+	} else {
+		delete obj;
+		_dlHandle = 0;
+	}
+
+	if (!_dlHandle) {
+		warning("elfloader: Failed loading plugin '%s'", _filename.toString(Common::Path::kNativeSeparator).c_str());
+		return false;
+	}
+
+	CharFunc buildDateFunc = (CharFunc)findSymbol("PLUGIN_getBuildDate");
+	if (!buildDateFunc) {
+		unloadPlugin();
+		warning("elfloader: plugin '%s' is missing symbols", _filename.toString(Common::Path::kNativeSeparator).c_str());
+		return false;
+	}
+
+	if (strncmp(gScummVMPluginBuildDate, buildDateFunc(), strlen(gScummVMPluginBuildDate))) {
+		unloadPlugin();
+		warning("elfloader: plugin '%s' has a different build date", _filename.toString(Common::Path::kNativeSeparator).c_str());
+		return false;
+	}
+
+	bool ret = DynamicPlugin::loadPlugin();
+
+#ifdef ELF_LOADER_CXA_ATEXIT
+	if (ret) {
+		// FIXME HACK: Reverse HACK of findSymbol() :P
+		VoidFunc tmp;
+		tmp = findSymbol("__dso_handle");
+		memcpy(&_dso_handle, &tmp, sizeof(VoidFunc));
+		debug(2, "elfloader: __dso_handle is %p", _dso_handle);
+	}
+#endif
+
+	_dlHandle->discardSymtab();
+
+	return ret;
+}
+
+void ELFPlugin::unloadPlugin() {
+	DynamicPlugin::unloadPlugin();
+
+	if (_dlHandle) {
+#ifdef ELF_LOADER_CXA_ATEXIT
+		if (_dso_handle) {
+			debug(2, "elfloader: calling __cxa_finalize");
+			__cxxabiv1::__cxa_finalize(_dso_handle);
+			_dso_handle = 0;
+		}
+#endif
+
+		if (!_dlHandle->close())
+			warning("elfloader: Failed unloading plugin '%s'", _filename.toString(Common::Path::kNativeSeparator).c_str());
+
+		delete _dlHandle;
+		_dlHandle = 0;
+	}
+}
+
+ /**
+  * We override this function in FilePluginProvider to allow the single
+  * plugin method to create a non-fragmenting memory allocation. We take
+  * the plugins found and tell the memory manager to allocate space for
+  * them.
+  */
+PluginList ELFPluginProvider::getPlugins() {
+	PluginList pl = FilePluginProvider::getPlugins();
+
+#if defined(UNCACHED_PLUGINS) && !defined(ELF_NO_MEM_MANAGER)
+	// This static downcast is safe because all of the plugins must
+	// be ELF plugins
+	for (PluginList::iterator p = pl.begin(); p != pl.end(); ++p) {
+		(static_cast<ELFPlugin *>(*p))->trackSize();
+	}
+
+	// The Memory Manager should now allocate space based on the information
+	// it collected
+	if (!pl.empty()) {
+		ELFMemMan.allocateHeap();
+	}
+#endif
+
+	return pl;
+}
+
+bool ELFPluginProvider::isPluginFilename(const Common::FSNode &node) const {
+	// Check the plugin suffix
+	Common::String filename = node.getFileName();
+
+	if (!filename.hasSuffix(".PLG") && !filename.hasSuffix(".plg") &&
+			!filename.hasSuffix(".PLUGIN") && !filename.hasSuffix(".plugin"))
+		return false;
+
+	return true;
+}
+
+#endif // defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)

backends/plugins/elf/elf-provider.h

@@ -0,0 +1,93 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef BACKENDS_PLUGINS_ELF_PROVIDER_H
+#define BACKENDS_PLUGINS_ELF_PROVIDER_H
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+#include "backends/plugins/elf/elf-loader.h"
+
+#include "common/fs.h"
+
+/**
+ * ELFPlugin
+ *
+ * Objects of this class are returned when the PluginManager calls
+ * getPlugins() on an ELFPluginProvider. An intermediary class for
+ * dealing with plugin files, ELFPlugin is responsible for creating/destroying
+ * a DLObject that handles the opening/loading/unloading of the plugin file whose
+ * path in the target backend's file system is "_filename".
+ */
+class ELFPlugin : public DynamicPlugin {
+protected:
+	typedef const char *(*CharFunc)();
+
+	DLObject *_dlHandle;
+	void *_dso_handle;
+
+	virtual VoidFunc findSymbol(const char *symbol);
+
+public:
+	ELFPlugin(const Common::Path &filename) :
+		DynamicPlugin(filename),
+		_dlHandle(0),
+		_dso_handle(0) {
+	}
+
+	virtual ~ELFPlugin() {
+		if (_dlHandle)
+			unloadPlugin();
+	}
+
+	virtual DLObject *makeDLObject() = 0;
+
+	virtual bool loadPlugin();
+	virtual void unloadPlugin();
+	void trackSize();
+};
+
+template<class T>
+class TemplatedELFPlugin : public ELFPlugin {
+public:
+	TemplatedELFPlugin(const Common::Path &filename) :
+		ELFPlugin(filename) {
+	}
+
+	virtual DLObject *makeDLObject() {
+		return new T();
+	}
+};
+
+
+class ELFPluginProvider : public FilePluginProvider {
+protected:
+	virtual Plugin *createPlugin(const Common::FSNode &node) const = 0;
+	virtual PluginList getPlugins();
+
+	bool isPluginFilename(const Common::FSNode &node) const;
+};
+
+#endif // defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+#endif /* BACKENDS_PLUGINS_ELF_PROVIDER_H */

backends/plugins/elf/elf32.h

@@ -0,0 +1,250 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef BACKENDS_ELF_H
+#define BACKENDS_ELF_H
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+/**
+ *  ELF stuff:
+ *  The contents of this file were gathered mainly from the SYSTEM V APPLICATION BINARY INTERFACE.
+ *  Processor-specific things were garnered from processor-specific supplements to the abi.
+ */
+
+typedef uint16 Elf32_Half, Elf32_Section;
+typedef uint32 Elf32_Word, Elf32_Addr, Elf32_Off;
+typedef int32 Elf32_Sword;
+typedef Elf32_Half Elf32_Versym;
+
+#define EI_NIDENT (16)
+#define SELFMAG   4
+
+/* ELF File format structures. Look up ELF structure for more details */
+
+// ELF header (contains info about the file)
+typedef struct {
+	byte		e_ident[EI_NIDENT];	/* Magic number and other info */
+	Elf32_Half	e_type;				/* Object file type */
+	Elf32_Half	e_machine;			/* Architecture */
+	Elf32_Word	e_version;			/* Object file version */
+	Elf32_Addr	e_entry;				/* Entry point virtual address */
+	Elf32_Off	e_phoff;				/* Program header table file offset */
+	Elf32_Off	e_shoff;				/* Section header table file offset */
+	Elf32_Word	e_flags;				/* Processor-specific flags */
+	Elf32_Half	e_ehsize;				/* ELF header size in bytes */
+	Elf32_Half	e_phentsize;			/* Program header table entry size */
+	Elf32_Half	e_phnum;				/* Program header table entry count */
+	Elf32_Half	e_shentsize;			/* Section header table entry size */
+	Elf32_Half	e_shnum;				/* Section header table entry count */
+	Elf32_Half	e_shstrndx;			/* Section header string table index */
+} Elf32_Ehdr;
+
+// Should be in e_ident
+#define ELFMAG		"\177ELF"	/* ELF Magic number */
+
+#define EI_CLASS	4			/* File class byte index */
+#define ELFCLASS32	1			/* 32-bit objects */
+
+#define EI_DATA		5			/* Data encoding byte index */
+#define ELFDATA2LSB	1			/* 2's complement, little endian */
+#define ELFDATA2MSB	2			/* 2's complement, big endian */
+
+#define EI_VERSION	6
+#define EV_CURRENT	1			/* Current version */
+
+// e_type values
+#define ET_NONE		0			/* no file type */
+#define ET_REL		1			/* relocatable */
+#define ET_EXEC		2			/* executable */
+#define ET_DYN		3			/* shared object */
+#define ET_CORE		4			/* core file */
+
+// e_machine values
+#define EM_MIPS		8
+#define EM_PPC		20
+#define EM_ARM		40
+#define EM_SH		42
+
+// Program header (contains info about segment)
+typedef struct {
+	Elf32_Word	p_type;		/* Segment type */
+	Elf32_Off	p_offset;	/* Segment file offset */
+	Elf32_Addr	p_vaddr;	/* Segment virtual address */
+	Elf32_Addr	p_paddr;	/* Segment physical address */
+	Elf32_Word	p_filesz;	/* Segment size in file */
+	Elf32_Word	p_memsz;	/* Segment size in memory */
+	Elf32_Word	p_flags;	/* Segment flags */
+	Elf32_Word	p_align;	/* Segment alignment */
+} Elf32_Phdr;
+
+// p_type values
+#define PT_NULL 		0			/* ignored */
+#define PT_LOAD			1			/* loadable segment */
+#define PT_DYNAMIC		2			/* dynamic linking info */
+#define PT_INTERP		3			/* info about interpreter */
+#define PT_NOTE			4			/* note segment */
+#define PT_SHLIB		5			/* reserved */
+#define PT_PHDR			6			/* Program header table */
+#define PT_MIPS_REGINFO	0x70000000	/* Register usage info for MIPS */
+#define PT_ARM_ARCHEXT	0x70000000	/* Platform architecture compatibility info for ARM */
+#define PT_ARM_EXIDX	0x70000001	/* Exception unwind tables for ARM */
+
+// p_flags value
+#define PF_X	1	/* execute */
+#define PF_W	2	/* write */
+#define PF_R	4	/* read */
+
+// Section header (contains info about section)
+typedef struct {
+	Elf32_Word	sh_name;		/* Section name (string tbl index) */
+	Elf32_Word	sh_type;		/* Section type */
+	Elf32_Word	sh_flags;		/* Section flags */
+	Elf32_Addr	sh_addr;		/* Section virtual addr at execution */
+	Elf32_Off	sh_offset;		/* Section file offset */
+	Elf32_Word	sh_size;		/* Section size in bytes */
+	Elf32_Word	sh_link;		/* Link to another section */
+	Elf32_Word	sh_info;		/* Additional section information */
+	Elf32_Word	sh_addralign;	/* Section alignment */
+	Elf32_Word	sh_entsize;		/* Entry size if section holds table */
+} Elf32_Shdr;
+
+// sh_type values
+#define SHT_NULL			0			/* Inactive section */
+#define SHT_PROGBITS		1			/* Proprietary */
+#define SHT_SYMTAB			2			/* Symbol table */
+#define SHT_STRTAB			3			/* String table */
+#define SHT_RELA			4			/* Relocation entries with addend */
+#define SHT_HASH			5			/* Symbol hash table */
+#define SHT_DYNAMIC			6			/* Info for dynamic linking */
+#define SHT_NOTE			7			/* Note section */
+#define SHT_NOBITS			8			/* Occupies no space */
+#define SHT_REL				9			/* Relocation entries without addend */
+#define SHT_SHLIB			10			/* Reserved */
+#define SHT_DYNSYM			11			/* Minimal set of dynamic linking symbols */
+#define SHT_MIPS_LIBLSIT	0x70000000	/* Info about dynamic shared object libs for MIPS*/
+#define SHT_MIPS_CONFLICT	0x70000002	/* Conflicts btw executables and shared objects for MIPS */
+#define SHT_MIPS_GPTAB		0x70000003	/* Global pointer table for MIPS*/
+#define SHT_ARM_EXIDX		0x70000001	/* Exception Index table for ARM*/
+#define SHT_ARM_PREEMPTMAP	0x70000002	/* BPABI DLL dynamic linking pre-emption map for ARM */
+#define SHT_ARM_ATTRIBUTES	0x70000003	/* Object file compatibility attributes for ARM*/
+
+// sh_flags values
+#define SHF_WRITE		0			/* writable section */
+#define SHF_ALLOC		2			/* section occupies memory */
+#define SHF_EXECINSTR	4			/* machine instructions */
+#define SHF_MIPS_GPREL	0x10000000	/* Must be made part of global data area for MIPS */
+
+// Symbol entry (contain info about a symbol)
+typedef struct {
+	Elf32_Word		st_name;	/* Symbol name (string tbl index) */
+	Elf32_Addr		st_value;	/* Symbol value */
+	Elf32_Word		st_size;	/* Symbol size */
+	byte			st_info;	/* Symbol type and binding */
+	byte			st_other;	/* Symbol visibility */
+	Elf32_Section	st_shndx;	/* Section index */
+} Elf32_Sym;
+
+// Extract from the st_info
+#define SYM_TYPE(x)		((x) & 0xf)
+#define SYM_BIND(x)		((x) >> 4)
+
+// Symbol binding values from st_info
+#define STB_LOCAL	0	/* Symbol not visible outside object */
+#define STB_GLOBAL	1	/* Symbol visible to all object files */
+#define STB_WEAK	2	/* Similar to STB_GLOBAL */
+
+// Symbol type values from st_info
+#define STT_NOTYPE	0	/* Not specified */
+#define STT_OBJECT	1	/* Data object e.g. variable */
+#define STT_FUNC	2	/* Function */
+#define STT_SECTION	3	/* Section */
+#define STT_FILE	4	/* Source file associated with object file */
+
+// Special section header index values from st_shndex
+#define SHN_UNDEF		0
+#define SHN_LOPROC		0xFF00	/* Extended values */
+#define SHN_ABS			0xFFF1	/* Absolute value: don't relocate */
+#define SHN_COMMON		0xFFF2	/* Common block. Not allocated yet */
+#define SHN_HIPROC		0xFF1F
+#define SHN_HIRESERVE	0xFFFF
+
+// Relocation entry with implicit addend (info about how to relocate)
+typedef struct {
+	Elf32_Addr	r_offset;	/* Address */
+	Elf32_Word	r_info;		/* Relocation type and symbol index */
+} Elf32_Rel;
+
+// Relocation entry with explicit addend (info about how to relocate)
+typedef struct {
+	Elf32_Addr	r_offset;	/* Address */
+	Elf32_Word	r_info;		/* Relocation type and symbol index */
+	Elf32_Sword	r_addend;	/* Addend */
+} Elf32_Rela;
+
+// Access macros for the relocation info
+#define REL_TYPE(x)		((byte) (x))	/* Extract relocation type */
+#define REL_INDEX(x)	((x)>>8)		/* Extract relocation index into symbol table */
+
+//MIPS relocation types
+#define R_MIPS_NONE		0
+#define R_MIPS_16		1
+#define R_MIPS_32		2
+#define R_MIPS_REL32	3
+#define R_MIPS_26		4
+#define R_MIPS_HI16		5
+#define R_MIPS_LO16		6
+#define R_MIPS_GPREL16	7
+#define R_MIPS_LITERAL	8
+#define R_MIPS_GOT16	9
+#define R_MIPS_PC16		10
+#define R_MIPS_CALL16	11
+#define R_MIPS_GPREL32	12
+#define R_MIPS_GOTHI16	13
+#define R_MIPS_GOTLO16	14
+#define R_MIPS_CALLHI16	15
+#define R_MIPS_CALLLO16	16
+
+// ARM relocation types
+#define R_ARM_NONE			0
+#define R_ARM_PC24			1
+#define R_ARM_ABS32			2
+#define R_ARM_THM_CALL		10
+#define R_ARM_CALL			28
+#define R_ARM_JUMP24		29
+#define R_ARM_TARGET1		38
+#define R_ARM_V4BX 			40
+#define R_ARM_PREL31 			42
+
+// PPC relocation types
+#define R_PPC_NONE			0
+#define R_PPC_ADDR32		1
+#define R_PPC_ADDR16_LO		4
+#define R_PPC_ADDR16_HI		5
+#define R_PPC_ADDR16_HA		6
+#define R_PPC_REL24			10
+#define R_PPC_REL32			26
+
+#endif // defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+#endif /* BACKENDS_ELF_H */

backends/plugins/elf/memory-manager.cpp

@@ -0,0 +1,177 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+#include "backends/plugins/elf/memory-manager.h"
+#include "common/debug.h"
+#include "common/util.h"
+#include <malloc.h>
+
+namespace Common {
+DECLARE_SINGLETON(ELFMemoryManager);
+}
+
+ELFMemoryManager::ELFMemoryManager() :
+	_heap(0), _heapSize(0), _heapAlign(0),
+	_trackAllocs(false), _measuredSize(0), _measuredAlign(0),
+	_bytesAllocated(0) {}
+
+ELFMemoryManager::~ELFMemoryManager() {
+	free(_heap);
+	_heap = 0;
+}
+
+void ELFMemoryManager::trackPlugin(bool value) {
+	assert(!_heap);
+
+	if (value == _trackAllocs)
+		return;
+
+	_trackAllocs = value;
+
+	if (_trackAllocs) {	// start measuring
+		// start tracking allocations
+		_measuredAlign = 0;
+
+	} else {	// we're done measuring
+		// get the total allocated size
+		uint32 measuredSize = _allocList.back().end() - _allocList.front().start;
+
+		_heapSize = MAX(_heapSize, measuredSize);
+		_heapAlign = MAX(_heapAlign, _measuredAlign);
+
+		_allocList.clear();
+		_bytesAllocated = 0;	// reset
+
+		debug(2, "measured a plugin of size %d. Max size %d. Max align %d", measuredSize, _heapSize, _heapAlign);
+	}
+}
+
+void ELFMemoryManager::trackAlloc(uint32 align, uint32 size) {
+	if (!_measuredAlign)
+		_measuredAlign = align;
+
+	// use the allocate function to simulate allocation
+	allocateOnHeap(align, size);
+}
+
+void ELFMemoryManager::allocateHeap() {
+	if (!_heapSize) {
+		warning("ELFMemoryManager: Unable to allocate the heap as its size could not be determined.");
+		return;
+	}
+
+	// The memory manager should only allocate once
+	assert (!_heap);
+
+	// clear the list
+	_allocList.clear();
+	_bytesAllocated = 0;
+
+	debug(2, "ELFMemoryManager: allocating %d bytes aligned at %d as the \
+			plugin heap", _heapSize, _heapAlign);
+
+	// prepare the heap
+	if (_heapAlign)
+		_heap = ::memalign(_heapAlign, _heapSize);
+	else
+		_heap = ::malloc(_heapSize);
+
+	assert(_heap);
+}
+
+void *ELFMemoryManager::pluginAllocate(uint32 size) {
+	if (_heap) {
+		return pluginAllocate(sizeof(void *), size);
+	}
+	return ::malloc(size);
+}
+
+void *ELFMemoryManager::pluginAllocate(uint32 align, uint32 size) {
+	if (_heap) {
+		return allocateOnHeap(align, size);
+	}
+	return ::memalign(align, size);
+}
+
+void ELFMemoryManager::pluginDeallocate(void *ptr) {
+	if (_heap) {
+		return deallocateFromHeap(ptr);
+	}
+	return ::free(ptr);
+}
+
+// Allocate space for the request in our heap
+void *ELFMemoryManager::allocateOnHeap(uint32 align, uint32 size) {
+	byte *lastAddress = (byte *)_heap;
+
+	// We can't allow allocations smaller than sizeof(Allocation). This could
+	// only be from non-plugin allocations and would cause infinite recursion
+	// when allocating our Allocation in the list.
+	if (size <= sizeof(Allocation))
+		return 0;
+
+	Common::List<Allocation>::iterator i;
+	for (i = _allocList.begin(); i != _allocList.end(); i++) {
+		if (i->start - lastAddress > (int)size)
+			break;
+		lastAddress = i->end();
+		// align to desired alignment
+		if (align) {
+			lastAddress = (byte *)( ((uint32)lastAddress + align - 1) & ~(align - 1) );
+		}
+	}
+
+	// Check if we exceeded our heap limit
+	// We skip this case if we're only tracking allocations
+	if (!_trackAllocs && ((uint32)lastAddress + size > (uint32)_heap + _heapSize)) {
+		debug(2, "failed to find space to allocate %d bytes", size);
+		return 0;
+	}
+
+	_allocList.insert(i, Allocation(lastAddress, size));
+	_bytesAllocated += size;
+
+	debug(7, "ELFMemoryManager: allocated %d bytes at %p. Total %d bytes",
+		size, lastAddress, _bytesAllocated);
+
+	return lastAddress;
+}
+
+void ELFMemoryManager::deallocateFromHeap(void *ptr) {
+	Common::List<Allocation>::iterator i;
+	for (i = _allocList.begin(); i != _allocList.end(); i++) {
+		if (i->start == ptr) {
+			_bytesAllocated -= (*i).size;
+
+			debug(7, "ELFMemoryManager: freed %d bytes at %p. Total %d bytes",
+				(*i).size, (*i).start, _bytesAllocated);
+
+			_allocList.erase(i);
+			break;
+		}
+	}
+}
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) */

backends/plugins/elf/memory-manager.h

@@ -0,0 +1,85 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef ELF_MEMORY_MANAGER_H
+#define ELF_MEMORY_MANAGER_H
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER)
+
+#include "common/singleton.h"
+#include "common/list.h"
+#include "common/mutex.h"
+
+/**
+ * A 'foolproof' way to prevent memory fragmentation. This class is used to
+ * serve as a permanent allocation to prevent the process of loading and
+ * unloading plugins from causing heavy fragmentation.
+ **/
+
+#define ELFMemMan		ELFMemoryManager::instance()
+
+class ELFMemoryManager : public Common::Singleton<ELFMemoryManager> {
+public:
+	void trackPlugin(bool value);
+	void trackAlloc(uint32 align, uint32 size);
+
+	void allocateHeap();
+
+	void *pluginAllocate(uint32 size);
+	void *pluginAllocate(uint32 align, uint32 size);
+	void pluginDeallocate(void *ptr);
+
+private:
+   friend class Common::Singleton<ELFMemoryManager>;
+
+	ELFMemoryManager();
+	~ELFMemoryManager();
+
+	void *allocateOnHeap(uint32 align, uint32 size);
+	void deallocateFromHeap(void *ptr);
+
+	struct Allocation {
+		byte *start;
+		uint32 size;
+		byte *end() { return start + size; }
+		Allocation(byte *a, uint32 b) : start(a), size(b) {}
+	};
+
+	// heap
+	void *_heap;
+	uint32 _heapAlign;			// alignment of the heap
+	uint32 _heapSize;			// size of the heap
+
+	// tracking allocations
+	bool _trackAllocs;		// whether we are currently tracking
+	uint32 _measuredSize;
+	uint32 _measuredAlign;
+
+	// real allocations
+	Common::List<Allocation> _allocList;
+	uint32 _bytesAllocated;
+};
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) */
+
+#endif /* ELF_MEMORY_MANAGER_H */

backends/plugins/elf/mips-loader.cpp

@@ -0,0 +1,340 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET)
+
+#include "backends/plugins/elf/mips-loader.h"
+#include "backends/plugins/elf/memory-manager.h"
+
+#include "common/debug.h"
+
+#define DEBUG_NUM 2
+
+bool MIPSDLObject::relocate(Elf32_Off offset, Elf32_Word size, byte *relSegment) {
+	Elf32_Rel *rel = 0;	// relocation entry
+
+	// Allocate memory for relocation table
+	if (!(rel = (Elf32_Rel *)malloc(size))) {
+		warning("elfloader: Could not allocate %d bytes for the relocation table", size);
+		return false;
+	}
+
+	// Read in our relocation table
+	if (!_file->seek(offset, SEEK_SET) || _file->read(rel, size) != size) {
+		warning("elfloader: Relocation table load failed.");
+		free(rel);
+		return false;
+	}
+
+	// Treat each relocation entry. Loop over all of them
+	uint32 cnt = size / sizeof(*rel);
+
+	debug(2, "elfloader: Loaded relocation table. %d entries. base address=%p", cnt, relSegment);
+
+	Elf32_Addr adjustedMainSegment = Elf32_Addr(_segment) - _segmentVMA;	// adjust for VMA offset
+
+	bool seenHi16 = false;			// For treating HI/LO16 commands
+	int32 firstHi16 = -1;			// Mark the point of the first hi16 seen
+	Elf32_Addr ahl = 0;				// Calculated addend
+	int32 a = 0;					// Addend: taken from the target
+
+	uint32 *lastTarget = 0;			// For processing hi16 when lo16 arrives
+	uint32 relocation = 0;
+	uint debugRelocs[10] = { 0 };	// For debugging
+	uint extendedHi16 = 0;			// Count extended hi16 treatments
+	Elf32_Addr lastHiSymVal = 0;
+	bool hi16InShorts = false;
+
+	// Loop over relocation entries
+	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.
+		uint32 *target = (uint32 *)((byte *)relSegment + rel[i].r_offset);
+
+		uint32 origTarget = *target;	// Save for debugging
+
+		// Act differently based on the type of relocation
+		switch (REL_TYPE(rel[i].r_info)) {
+		case R_MIPS_NONE:
+			break; // No relocation
+		case R_MIPS_HI16:							// Absolute addressing.
+			if (sym->st_shndx < SHN_LOPROC &&		// Only shift for plugin section (ie. has a real section index)
+				firstHi16 < 0) {					// Only process first in block of HI16s
+				firstHi16 = i;						// Keep the first Hi16 we saw
+				seenHi16 = true;
+				ahl = (*target & 0xffff) << 16;		// Take lower 16 bits shifted up
+
+				lastHiSymVal = sym->st_value;
+				hi16InShorts = ShortsMan.inGeneralSegment((char *)sym->st_value); // Fix for problem with switching btw segments
+				if (debugRelocs[0]++ < DEBUG_NUM)	// Print only a set number
+					debug(8, "elfloader: R_MIPS_HI16: i=%d, offset=%x, ahl = %x, target = %x",
+							i, rel[i].r_offset, ahl, *target);
+			}
+			break;
+
+		case R_MIPS_LO16:							// Absolute addressing. Needs a HI16 to come before it
+			if (sym->st_shndx < SHN_LOPROC) {		// Only shift for plugin section. (ie. has a real section index)
+				if (!seenHi16) {					// We MUST have seen HI16 first
+					debug(8, "elfloader: R_MIPS_LO16 w/o preceding R_MIPS_HI16 at relocation %d!", i);
+					free(rel);
+					return false;
+				}
+
+				// Fix: bug in gcc makes LO16s connect to wrong HI16s sometimes (shorts and regular segment)
+				// Note that we can check the entire shorts segment because the executable's shorts don't belong to this plugin section
+				// and will be screened out above
+				bool lo16InShorts = ShortsMan.inGeneralSegment((char *)sym->st_value);
+
+				// Correct the bug by getting the proper value in ahl (taken from the current symbol)
+				if ((hi16InShorts && !lo16InShorts) || (!hi16InShorts && lo16InShorts)) {
+					ahl -= (lastHiSymVal & 0xffff0000);		// We assume gcc meant the same offset
+					ahl += (sym->st_value & 0xffff0000);
+				}
+
+				ahl &= 0xffff0000;				// Clean lower 16 bits for repeated LO16s
+				a = *target & 0xffff;			// Take lower 16 bits of the target
+				a = (a << 16) >> 16;			// Sign extend them
+				ahl += a;						// Add lower 16 bits. AHL is now complete
+
+				// Fix: we can have LO16 access to the short segment sometimes
+				if (lo16InShorts)
+					relocation = ahl + _shortsSegment->getOffset();		// Add in the short segment offset
+				else	// It's in the regular segment
+					relocation = ahl + adjustedMainSegment;				// Add in the new offset for the segment
+
+				if (firstHi16 >= 0) {					// We haven't treated the HI16s yet so do it now
+					for (uint32 j = firstHi16; j < i; j++) {
+						if (REL_TYPE(rel[j].r_info) != R_MIPS_HI16)
+							continue;	// Skip over non-Hi16s
+
+						lastTarget = (uint32 *)((char *)relSegment + rel[j].r_offset);	// get hi16 target
+						*lastTarget &= 0xffff0000;		// Clear the lower 16 bits of the last target
+						*lastTarget |= (relocation >> 16) & 0xffff;	// Take the upper 16 bits of the relocation
+						if (relocation & 0x8000)
+							(*lastTarget)++;	// Subtle: we need to add 1 to the HI16 in this case
+					}
+
+					firstHi16 = -1;						// Reset so we'll know we treated it
+				} else {
+					extendedHi16++;
+				}
+
+				*target &= 0xffff0000;						// Clear the lower 16 bits of current target
+				*target |= relocation & 0xffff;				// Take the lower 16 bits of the relocation
+
+				if (debugRelocs[1]++ < DEBUG_NUM)
+					debug(8, "elfloader: R_MIPS_LO16: i=%d, offset=%x, a=%x, ahl = %x, "
+							"lastTarget = %x, origt = %x, target = %x",
+							i, rel[i].r_offset, a, ahl, *lastTarget, origTarget, *target);
+
+				if (lo16InShorts && debugRelocs[2]++ < DEBUG_NUM)
+					debug(8, "elfloader: R_MIPS_LO16s: i=%d, offset=%x, a=%x, ahl = %x, "
+							"lastTarget = %x, origt = %x, target = %x",
+							i, rel[i].r_offset, a, ahl, *lastTarget, origTarget, *target);
+			}
+			break;
+
+		case R_MIPS_26:													// Absolute addressing (for jumps and branches only)
+			if (sym->st_shndx < SHN_LOPROC) {							// Only relocate for main segment
+				a = *target & 0x03ffffff;								// Get 26 bits' worth of the addend
+				a = (a << 6) >> 6; 										// Sign extend a
+				relocation = ((a << 2) + adjustedMainSegment) >> 2;		// a already points to the target. Add our offset
+				*target &= 0xfc000000;									// Clean lower 26 target bits
+				*target |= (relocation & 0x03ffffff);
+
+				if (debugRelocs[3]++ < DEBUG_NUM)
+					debug(8, "elfloader: R_MIPS_26: i=%d, offset=%x, symbol=%d, stinfo=%x, "
+							"a=%x, origTarget=%x, target=%x",
+							i, rel[i].r_offset, REL_INDEX(rel[i].r_info), sym->st_info, a, origTarget, *target);
+			} else {
+				if (debugRelocs[4]++ < DEBUG_NUM)
+					debug(8, "elfloader: R_MIPS_26: i=%d, offset=%x, symbol=%d, stinfo=%x, "
+							"a=%x, origTarget=%x, target=%x",
+							i, rel[i].r_offset, REL_INDEX(rel[i].r_info), sym->st_info, a, origTarget, *target);
+			}
+			break;
+
+		case R_MIPS_GPREL16:												// GP Relative addressing
+			if (_shortsSegment->getOffset() != 0 &&							// Only relocate if we shift the shorts section
+					ShortsMan.inGeneralSegment((char *) sym->st_value)) {	// Only relocate things in the plugin hole
+				a = *target & 0xffff;										// Get 16 bits' worth of the addend
+				a = (a << 16) >> 16;										// Sign extend it
+
+				relocation = a + _shortsSegment->getOffset();
+
+				*target &= 0xffff0000;					// Clear the lower 16 bits of the target
+				*target |= relocation & 0xffff;
+
+				if (debugRelocs[5]++ < DEBUG_NUM)
+					debug(8, "elfloader: R_MIPS_GPREL16: i=%d, a=%x, gpVal=%x, origTarget=%x, "
+							"target=%x, offset=%x",
+							i, a, _gpVal, origTarget, *target, _shortsSegment->getOffset());
+			}
+
+			break;
+
+		case R_MIPS_32:									// Absolute addressing
+			if (sym->st_shndx < SHN_LOPROC) {			// Only shift for plugin section.
+				a = *target;							// Get full 32 bits of addend
+
+				if (ShortsMan.inGeneralSegment((char *)sym->st_value))	// Check if we're in the shorts segment
+					relocation = a + _shortsSegment->getOffset();		// Shift by shorts offset
+				else													// We're in the main section
+					relocation = a + adjustedMainSegment;				// Shift by main offset
+
+				*target = relocation;
+
+				if (debugRelocs[6]++ < DEBUG_NUM)
+					debug(8, "elfloader: R_MIPS_32: i=%d, a=%x, origTarget=%x, target=%x",
+							i, a, origTarget, *target);
+			}
+
+			break;
+
+		default:
+			warning("elfloader: Unknown relocation type %x at relocation %d.", REL_TYPE(rel[i].r_info), i);
+			free(rel);
+			return false;
+		}
+	}
+
+	debug(2, "elfloader: Done with relocation. extendedHi16=%d", extendedHi16);
+
+	free(rel);
+	return true;
+}
+
+bool MIPSDLObject::relocateRels(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr) {
+	// Loop over sections, finding relocation sections
+	for (uint32 i = 0; i < ehdr->e_shnum; i++) {
+		Elf32_Shdr *curShdr = &(shdr[i]);
+		//Elf32_Shdr *linkShdr = &(shdr[curShdr->sh_info]);
+
+		if (curShdr->sh_type == SHT_REL &&							// Check for a relocation section
+				curShdr->sh_entsize == sizeof(Elf32_Rel) &&			// Check for proper relocation size
+				int32(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 (!ShortsMan.inGeneralSegment((char *)shdr[curShdr->sh_info].sh_addr)) {			// regular segment
+				if (!relocate(curShdr->sh_offset, curShdr->sh_size, _segment - _segmentVMA))
+					return false;
+			} else {	// In Shorts segment
+				if (!relocate(curShdr->sh_offset, curShdr->sh_size, (byte *)_shortsSegment->getOffset()))
+					return false;
+			}
+		}
+	}
+
+	return true;
+}
+
+void MIPSDLObject::relocateSymbols(ptrdiff_t offset) {
+	// Loop over symbols, add relocation offset
+	Elf32_Sym *s = _symtab;
+
+	for (uint32 c = _symbol_cnt; c--; s++) {
+		// Make sure we don't relocate special valued symbols
+		if (s->st_shndx < SHN_LOPROC) {
+			if (!ShortsMan.inGeneralSegment((char *)s->st_value)) {
+				if (s->st_value < _segmentVMA)
+					s->st_value = _segmentVMA;	// deal with symbols referring to sections, which start before the VMA
+
+				s->st_value += offset;
+
+				if (s->st_value < Elf32_Addr(_segment) || s->st_value > Elf32_Addr(_segment) + _segmentSize)
+					warning("elfloader: Symbol out of bounds! st_value = %x", s->st_value);
+			} else {	// shorts section
+				s->st_value += _shortsSegment->getOffset();
+				if (!_shortsSegment->inSegment((char *)s->st_value))
+					warning("elfloader: Symbol out of bounds! st_value = %x", s->st_value);
+			}
+		}
+	}
+}
+
+bool MIPSDLObject::loadSegment(Elf32_Phdr *phdr) {
+	byte *baseAddress = 0;
+
+	// We need to take account of non-allocated segment for shorts
+	if (phdr->p_flags & PF_X) {	// This is a relocated segment
+		// Attempt to allocate memory for segment
+		_segment = (byte *)allocateMemory(phdr->p_align, phdr->p_memsz);
+
+		if (!_segment) {
+			warning("elfloader: Out of memory.");
+			return false;
+		}
+
+		debug(2, "elfloader: Allocated segment @ %p", _segment);
+
+		// Get offset to load segment into
+		baseAddress = _segment;
+		_segmentSize = phdr->p_memsz;
+		_segmentVMA = phdr->p_vaddr;
+
+	} else {						// This is a shorts section.
+		_shortsSegment = ShortsMan.newSegment(phdr->p_memsz, (char *)phdr->p_vaddr);
+
+		baseAddress = (byte *)_shortsSegment->getStart();
+		debug(2, "elfloader: Shorts segment @ %p to %p. Segment wants to be at %x. Offset=%x",
+				_shortsSegment->getStart(), _shortsSegment->getEnd(), phdr->p_vaddr,
+				_shortsSegment->getOffset());
+	}
+
+	// Set .sbss segment to 0 if necessary
+	if (phdr->p_memsz > phdr->p_filesz) {
+		debug(2, "elfloader: Setting %p to %p to 0 for bss", baseAddress + phdr->p_filesz,
+				baseAddress + phdr->p_memsz);
+		memset(baseAddress + phdr->p_filesz, 0, phdr->p_memsz - phdr->p_filesz);
+	}
+
+	debug(2, "elfloader: Reading the segment into memory");
+
+	// Read the segment into memory
+	if (!_file->seek(phdr->p_offset, SEEK_SET) ||
+			_file->read(baseAddress, phdr->p_filesz) != phdr->p_filesz) {
+		warning("elfloader: Segment load failed.");
+		return false;
+	}
+
+	debug(2, "elfloader: Segment has been read into memory");
+
+	return true;
+}
+
+// Unload all objects from memory
+void MIPSDLObject::unload() {
+	DLObject::unload();
+	freeShortsSegment();
+}
+
+void MIPSDLObject::freeShortsSegment() {
+	if (_shortsSegment) {
+		ShortsMan.deleteSegment(_shortsSegment);
+		_shortsSegment = 0;
+	}
+}
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET) */

backends/plugins/elf/mips-loader.h

@@ -0,0 +1,59 @@
+
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef BACKENDS_PLUGINS_MIPS_LOADER_H
+#define BACKENDS_PLUGINS_MIPS_LOADER_H
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET)
+
+#include "backends/plugins/elf/elf-loader.h"
+#include "backends/plugins/elf/shorts-segment-manager.h"
+
+class MIPSDLObject : public DLObject {
+protected:
+	ShortSegmentManager::Segment *_shortsSegment;	// For assigning shorts ranges
+	uint32 _gpVal;									// Value of Global Pointer
+
+	virtual bool relocate(Elf32_Off offset, Elf32_Word size, byte *relSegment);
+	virtual bool relocateRels(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr);
+	virtual void relocateSymbols(ptrdiff_t offset);
+	virtual bool loadSegment(Elf32_Phdr *phdr);
+	virtual void unload();
+
+	void freeShortsSegment();
+
+public:
+	MIPSDLObject() :
+		DLObject() {
+		_shortsSegment = NULL;
+		_gpVal = 0;
+	}
+	~MIPSDLObject() {
+		freeShortsSegment();
+	}
+};
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET) */
+
+#endif /* BACKENDS_PLUGINS_MIPS_LOADER_H */

backends/plugins/elf/plugin.syms

@@ -0,0 +1,10 @@
+PLUGIN_getBuildDate
+PLUGIN_getVersion
+PLUGIN_getType
+PLUGIN_getTypeVersion
+PLUGIN_getObject
+___plugin_ctors
+___plugin_ctors_end
+___plugin_dtors
+___plugin_dtors_end
+__dso_handle

backends/plugins/elf/ppc-loader.cpp

@@ -0,0 +1,127 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#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: Could not allocate %d bytes for the relocation table", size);
+		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_NONE:
+			debug(8, "elfloader: R_PPC_NONE");
+			break;
+		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) */

backends/plugins/elf/ppc-loader.h

@@ -0,0 +1,39 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef BACKENDS_PLUGINS_PPC_LOADER_H
+#define BACKENDS_PLUGINS_PPC_LOADER_H
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(PPC_TARGET)
+
+#include "backends/plugins/elf/elf-loader.h"
+
+class PPCDLObject : public DLObject {
+protected:
+	virtual bool relocate(Elf32_Off offset, Elf32_Word size, byte *relSegment);
+	virtual bool relocateRels(Elf32_Ehdr *ehdr, Elf32_Shdr *shdr);
+};
+
+#endif /* defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(PPC_TARGET) */
+
+#endif /* BACKENDS_PLUGINS_PPC_LOADER_H */

backends/plugins/elf/shorts-segment-manager.cpp

@@ -0,0 +1,86 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET)
+
+#include "backends/plugins/elf/shorts-segment-manager.h"
+
+#include "common/debug.h"
+#include "common/textconsole.h"
+
+extern char __plugin_hole_start;	// Indicates start of hole in program file for shorts
+extern char __plugin_hole_end;		// Indicates end of hole in program file
+extern char _gp[];					// Value of gp register
+
+namespace Common {
+DECLARE_SINGLETON(ShortSegmentManager);	// For singleton
+}
+
+ShortSegmentManager::ShortSegmentManager() {
+	_shortsStart = &__plugin_hole_start ;	//shorts segment begins at the plugin hole we made when linking
+	_shortsEnd = &__plugin_hole_end;		//and ends at the end of that hole.
+}
+
+ShortSegmentManager::Segment *ShortSegmentManager::newSegment(uint32 size, char *origAddr) {
+	char *lastAddress = origAddr;
+	Common::List<Segment *>::iterator i;
+
+	// Find a block that fits, starting from the beginning
+	for (i = _list.begin(); i != _list.end(); ++i) {
+		char *currAddress = (*i)->getStart();
+
+		if (uint32(currAddress) - uint32(lastAddress) >= size)
+			break;
+
+		lastAddress = (*i)->getEnd();
+	}
+
+	if ((Elf32_Addr)lastAddress & 3)
+		lastAddress += 4 - ((Elf32_Addr)lastAddress & 3);	// Round up to multiple of 4
+
+	if (lastAddress + size > _shortsEnd) {
+		warning("elfloader: No space in shorts segment for %x bytes. Last address is %p, max address is %p.",
+				size, lastAddress, _shortsEnd);
+		return 0;
+	}
+
+	Segment *seg = new Segment(lastAddress, size, origAddr);	// Create a new segment
+
+	if (lastAddress + size > _highestAddress)
+		_highestAddress = lastAddress + size;	// Keep track of maximum
+
+	_list.insert(i, seg);
+
+	debug(2, "elfloader: Shorts segment size %x allocated. End = %p. Remaining space = %x. Highest so far is %p.",
+			size, lastAddress + size, _shortsEnd - _list.back()->getEnd(), _highestAddress);
+
+	return seg;
+}
+
+void ShortSegmentManager::deleteSegment(ShortSegmentManager::Segment *seg) {
+	debug(2, "elfloader: Deleting shorts segment from %p to %p.", seg->getStart(), seg->getEnd());
+	_list.remove(seg);
+	delete seg;
+}
+
+#endif // defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET)

backends/plugins/elf/shorts-segment-manager.h

@@ -0,0 +1,112 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef SHORTS_SEGMENT_MANAGER_H
+#define SHORTS_SEGMENT_MANAGER_H
+
+#include "common/scummsys.h"
+
+#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET)
+
+#include "backends/plugins/elf/elf32.h"
+
+#include "common/singleton.h"
+#include "common/list.h"
+
+#define ShortsMan ShortSegmentManager::instance()
+
+/**
+ * ShortSegmentManager
+ *
+ * Since MIPS is limited to 32 bits per instruction, loading data that's further away than 16 bits
+ * takes several instructions. Thus, small global data (which is likely to be accessed a lot from
+ * multiple locations) is often put into a GP-relative area (GP standing for the global pointer register)
+ * in MIPS processors. This class manages these segments of small global data, and is used by the
+ * member functions of MIPSDLObject, which query in information from this manager in order to deal with
+ * this segment during the loading/unloading of plugins.
+ *
+ * Since there's no true dynamic linker to change the GP register between plugins and the main engine,
+ * custom ld linker scripts for both the main executable and the plugins ensure the GP-area is in the
+ * same place for both. The ShortSegmentManager accesses this place via the symbols __plugin_hole_start
+ * and __plugin_hole_end, which are defined in those custom ld linker scripts.
+ */
+class ShortSegmentManager : public Common::Singleton<ShortSegmentManager> {
+private:
+	char *_shortsStart;
+	char *_shortsEnd;
+
+public:
+	char *getShortsStart() {
+		return _shortsStart;
+	}
+
+	// Returns whether or not an absolute address is in the GP-relative section.
+	bool inGeneralSegment(char *addr) {
+		return (addr >= _shortsStart && addr < _shortsEnd);
+	}
+
+	class Segment {
+	private:
+		friend class ShortSegmentManager;
+		Segment(char *start, uint32 size, char *origAddr) :
+			_startAddress(start),
+			_size(size),
+			_origAddress(origAddr) {
+		}
+
+		virtual ~Segment() {
+		}
+
+		char *_startAddress;		// Start of shorts segment in memory
+		uint32 _size;				// Size of shorts segment
+		char *_origAddress;			// Original address this segment was supposed to be at
+
+	public:
+		char *getStart() {
+			return _startAddress;
+		}
+
+		char *getEnd() {
+			return (_startAddress + _size);
+		}
+
+		Elf32_Addr getOffset() {
+			return (Elf32_Addr)(_startAddress - _origAddress);
+		}
+
+		bool inSegment(char *addr) {
+			return (addr >= _startAddress && addr <= _startAddress + _size);
+		}
+	};
+
+	Segment *newSegment(uint32 size, char *origAddr);
+	void deleteSegment(Segment *);
+
+private:
+	ShortSegmentManager();
+	friend class Common::Singleton<ShortSegmentManager>;
+	Common::List<Segment *> _list;
+	char *_highestAddress;
+};
+
+#endif // defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET)
+
+#endif /* SHORTS_SEGMENT_MANAGER_H */

backends/plugins/elf/version.cpp

@@ -0,0 +1,27 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "backends/plugins/elf/version.h"
+
+#ifdef USE_ELF_LOADER
+	const char *gScummVMPluginBuildDate __attribute__((visibility("hidden"))) =
+		__DATE__ " " __TIME__;
+#endif

backends/plugins/elf/version.h

@@ -0,0 +1,31 @@
+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef BACKENDS_PLUGINS_ELF_VERSION_H
+#define BACKENDS_PLUGINS_ELF_VERSION_H
+
+#include "common/scummsys.h"
+
+#ifdef USE_ELF_LOADER
+extern const char *gScummVMPluginBuildDate;
+#endif
+
+#endif