forked from M-Labs/nac3
reloc: add PC-relative relocation support
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e3ed41ff32
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512b6bac12
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@ -59,7 +59,8 @@ impl Relocatable for Elf32_Rela {
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enum RelType {
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enum RelType {
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None,
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None,
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Relative,
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Relative,
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Lookup,
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LookupAbs,
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LookupRel,
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}
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}
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impl RelType {
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impl RelType {
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@ -76,9 +77,11 @@ impl RelType {
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Some(RelType::Relative),
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Some(RelType::Relative),
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R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT
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R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT
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if arch == Arch::OpenRisc => Some(RelType::Lookup),
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if arch == Arch::OpenRisc => Some(RelType::LookupAbs),
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R_ARM_GLOB_DAT | R_ARM_JUMP_SLOT | R_ARM_ABS32
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R_ARM_GLOB_DAT | R_ARM_JUMP_SLOT | R_ARM_ABS32
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if arch == Arch::Arm => Some(RelType::Lookup),
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if arch == Arch::Arm => Some(RelType::LookupAbs),
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R_ARM_PREL31 if arch == Arch::Arm => Some(RelType::LookupRel),
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_ =>
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_ =>
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None
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None
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@ -106,31 +109,38 @@ pub fn relocate<R: Relocatable>(
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let rel_type = RelType::new(arch, rel.type_info())
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let rel_type = RelType::new(arch, rel.type_info())
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.ok_or("unsupported relocation type")?;
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.ok_or("unsupported relocation type")?;
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let value;
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let value = match rel_type {
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match rel_type {
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RelType::None =>
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RelType::None =>
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return Ok(()),
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return Ok(()),
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RelType::Relative => {
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RelType::Relative => {
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let addend = rel.addend(&lib.image);
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let addend = rel.addend(&lib.image);
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value = lib.image.ptr().wrapping_offset(addend as isize) as Elf32_Word;
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lib.image.ptr().wrapping_offset(addend as isize) as Elf32_Word
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}
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}
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RelType::Lookup => {
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RelType::LookupAbs | RelType::LookupRel => {
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let sym = sym.ok_or("relocation requires an associated symbol")?;
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let sym = sym.ok_or("relocation requires an associated symbol")?;
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let sym_name = lib.name_starting_at(sym.st_name as usize)?;
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let sym_name = lib.name_starting_at(sym.st_name as usize)?;
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if let Some(addr) = lib.lookup(sym_name) {
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let sym_addr = if let Some(addr) = lib.lookup(sym_name) {
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// First, try to resolve against itself.
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// First, try to resolve against itself.
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trace!("looked up symbol {} in image", format_sym_name(sym_name));
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trace!("looked up symbol {} in image", format_sym_name(sym_name));
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value = addr;
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addr
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} else if let Some(addr) = resolve(sym_name) {
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} else if let Some(addr) = resolve(sym_name) {
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// Second, call the user-provided function.
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// Second, call the user-provided function.
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trace!("resolved symbol {:?}", format_sym_name(sym_name));
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trace!("resolved symbol {:?}", format_sym_name(sym_name));
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value = addr;
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addr
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} else {
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} else {
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// We couldn't find it anywhere.
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// We couldn't find it anywhere.
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return Err(Error::Lookup(format_sym_name(sym_name)))
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return Err(Error::Lookup(format_sym_name(sym_name)))
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};
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match rel_type {
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RelType::LookupAbs => sym_addr,
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RelType::LookupRel =>
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sym_addr.wrapping_sub(
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lib.image.ptr().wrapping_offset(rel.offset() as isize) as Elf32_Addr),
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_ => unreachable!()
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}
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}
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}
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}
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}
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}
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@ -145,7 +155,7 @@ pub fn rebind(
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let rel_type = RelType::new(arch, rela.type_info())
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let rel_type = RelType::new(arch, rela.type_info())
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.ok_or("unsupported relocation type")?;
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.ok_or("unsupported relocation type")?;
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match rel_type {
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match rel_type {
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RelType::Lookup => {
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RelType::LookupAbs => {
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let sym = lib.symtab().get(ELF32_R_SYM(rela.r_info) as usize)
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let sym = lib.symtab().get(ELF32_R_SYM(rela.r_info) as usize)
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.ok_or("symbol out of bounds of symbol table")?;
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.ok_or("symbol out of bounds of symbol table")?;
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let sym_name = lib.name_starting_at(sym.st_name as usize)?;
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let sym_name = lib.name_starting_at(sym.st_name as usize)?;
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