/*
* $Id$
*
* Copyright (C) 2003-2014 JNode.org
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.jnode.linker;
import java.io.IOException;
import org.jnode.assembler.Label;
import org.jnode.assembler.NativeStream;
import org.jnode.assembler.UnresolvedObjectRefException;
import org.jnode.assembler.x86.X86BinaryAssembler;
import org.jnode.build.BuildException;
/**
* Build the boot image from an assembler compiled bootstrap (in ELF format)
* combined with the precompiled Java classes.
*/
public class ElfLinker {
private X86BinaryAssembler os;
private int start;
private int baseAddr;
public ElfLinker(X86BinaryAssembler os) {
this.os = os;
baseAddr = (int) os.getBaseAddr();
}
/**
* Load an ELF object file with a given name and link it into the native
* stream.
*/
public void loadElfObject(String name) throws BuildException {
Elf elf;
try {
elf = Elf.newFromFile(name);
loadElfObject(elf);
} catch (IOException ex) {
throw new BuildException(ex);
}
}
/**
* Load an ELF object file with a given name and link it into the native
* stream.
*/
public void loadElfObject(Elf elf) throws BuildException {
if (!elf.isRel()) {
throw new BuildException("Elf object is not relocatable");
}
final Section text = elf.getSectionByName(".text");
if (text == null) {
throw new BuildException(".text section not found");
}
// Write the code
start = os.getLength();
final byte[] tdata = text.getBody();
os.write(tdata, 0, tdata.length);
// Add all resolved symbols
final int symCnt = elf.getNoSymbols();
for (int i = 1; i < symCnt; i++) {
final Symbol sym = elf.getSymbol(i);
final Section sec = sym.getSection();
if (sec == text) {
// System.out.println(sym);
X86BinaryAssembler.X86ObjectRef ref = (X86BinaryAssembler.X86ObjectRef) os
.getObjectRef(new Label(sym.getName()));
ref.setPublic();
if (!sym.isUndef()) {
// System.out.println("Defined symbol at " + sym.getValue()
// + " [" + sym.getName() + "]");
ref.setOffset((int) sym.getValue() + start);
} else {
System.out.println("Undefined symbol: " + sym.getName());
}
} else if ((sec != null) && !sym.isUndef()) {
System.out
.println("Symbol '" + sym.getName()
+ "' refers to unknown section '"
+ sec.getName() + "'");
}
}
// Add all relocation items
Section rels = elf.getSectionByName(".rel.text");
if (rels == null) {
rels = elf.getSectionByName(".rela.text");
}
if (rels != null) {
final int relocCnt = rels.getNoRelocs();
for (int i = 0; i < relocCnt; i++) {
try {
final Reloc r = rels.getReloc(i);
final String symName = r.getSymbol().getName();
final boolean hasSymName = (symName.length() > 0);
final boolean hasAddEnd = r.hasAddEnd();
final long addr = r.getAddress() + start;
final long addend = r.getAddEnd();
final Reloc.Type relocType = r.getRelocType();
if ((relocType == Reloc.R_386_32) && !hasAddEnd) {
resolve_R386_32(addr, symName, hasSymName);
} else if ((relocType == Reloc.R_386_PC32) && !hasAddEnd) {
resolve_R386_PC32(addr, symName, hasSymName);
} else if ((relocType == Reloc.R_X86_64_32) && hasAddEnd) {
resolve_R_X86_64_32(addr, addend, symName, hasSymName);
} else if ((relocType == Reloc.R_X86_64_64) && hasAddEnd) {
resolve_R_X86_64_64(addr, addend, symName, hasSymName);
} else {
throw new BuildException("Unknown relocation type "
+ relocType);
}
} catch (UnresolvedObjectRefException ex) {
throw new BuildException(ex);
}
}
}
}
/**
* Resolve an absolute 32-bit address.
*
* @param addr
* @param symName
* @param hasSymName
* @throws UnresolvedObjectRefException
*/
private final void resolve_R386_32(long addr, String symName,
boolean hasSymName) throws UnresolvedObjectRefException {
if (!hasSymName) {
os.set32((int) addr, os.get32((int) addr) + start + baseAddr);
} else {
final NativeStream.ObjectRef ref = os.getObjectRef(new Label(
symName));
if (ref.isResolved()) {
os.set32((int) addr, ref.getOffset() + baseAddr);
} else {
os.set32((int) addr, -baseAddr);
ref.addUnresolvedLink((int) addr, 4);
}
}
}
/**
* Resolve an pc-relative 32-bit address.
*
* @param addr
* @param symName
* @param hasSymName
* @throws UnresolvedObjectRefException
*/
private final void resolve_R386_PC32(long addr, String symName,
boolean hasSymName) throws UnresolvedObjectRefException {
final NativeStream.ObjectRef ref = os.getObjectRef(new Label(symName));
if (ref.isResolved()) {
os.set32((int) addr, (int) (ref.getOffset() - (addr + 4)));
} else {
ref.addUnresolvedLink((int) addr, 4);
}
}
/**
* Resolve a direct 32 bit zero extended address.
*
* @param addr
* @param symName
* @param hasSymName
* @throws UnresolvedObjectRefException
*/
private final void resolve_R_X86_64_32(long addr, long addend,
String symName, boolean hasSymName)
throws UnresolvedObjectRefException {
if (!hasSymName) {
os.set32((int) addr, (int) (addend + start + baseAddr));
} else {
final NativeStream.ObjectRef ref = os.getObjectRef(new Label(
symName));
if (ref.isResolved()) {
os.set32((int) addr,
(int) (ref.getOffset() + baseAddr + addend));
} else {
os.set32((int) addr, (int) -(baseAddr + addend));
ref.addUnresolvedLink((int) addr, 4);
}
}
}
/**
* Resolve a direct 64 bit address.
*
* @param addr
* @param symName
* @param hasSymName
* @throws UnresolvedObjectRefException
*/
private final void resolve_R_X86_64_64(long addr, long addend,
String symName, boolean hasSymName)
throws UnresolvedObjectRefException {
if (!hasSymName) {
os.set64((int) addr, addend + start + baseAddr);
} else {
final NativeStream.ObjectRef ref = os.getObjectRef(new Label(
symName));
if (ref.isResolved()) {
os.set64((int) addr, ref.getOffset() + baseAddr + addend);
} else {
os.set64((int) addr, -(baseAddr + addend));
ref.addUnresolvedLink((int) addr, 8);
}
}
}
}