libdyld: refactor and fix multiarch support
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9dfddd60c5
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@ -5,6 +5,33 @@ use elf::*;
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pub mod elf;
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum Arch {
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Arm,
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OpenRisc,
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}
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impl Arch {
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fn detect(ehdr: &Elf32_Ehdr) -> Option<Self> {
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const IDENT_OPENRISC: [u8; EI_NIDENT] = [
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ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
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ELFCLASS32, ELFDATA2MSB, EV_CURRENT, ELFOSABI_NONE,
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/* ABI version */ 0, /* padding */ 0, 0, 0, 0, 0, 0, 0
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];
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const IDENT_ARM: [u8; EI_NIDENT] = [
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ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
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ELFCLASS32, ELFDATA2LSB, EV_CURRENT, ELFOSABI_NONE,
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/* ABI version */ 0, /* padding */ 0, 0, 0, 0, 0, 0, 0
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];
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match (ehdr.e_ident, ehdr.e_machine) {
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(IDENT_ARM, EM_ARM) => Some(Arch::Arm),
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(IDENT_OPENRISC, EM_OPENRISC) => Some(Arch::OpenRisc),
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_ => None,
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}
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}
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}
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fn read_unaligned<T: Copy>(data: &[u8], offset: usize) -> Result<T, ()> {
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if data.len() < offset + mem::size_of::<T>() {
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Err(())
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@ -83,6 +110,7 @@ pub struct Library<'a> {
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pltrel: &'a [Elf32_Rela],
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hash_bucket: &'a [Elf32_Word],
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hash_chain: &'a [Elf32_Word],
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arch: Arch,
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}
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impl<'a> Library<'a> {
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@ -133,20 +161,24 @@ impl<'a> Library<'a> {
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// This is unsafe because it mutates global data (the PLT).
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pub unsafe fn rebind(&self, name: &[u8], addr: Elf32_Word) -> Result<(), Error<'a>> {
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for rela in self.pltrel.iter() {
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match ELF32_R_TYPE(rela.r_info) {
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R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT |
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R_ARM_GLOB_DAT | R_ARM_JUMP_SLOT => {
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let sym = self.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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let sym_name = self.name_starting_at(sym.st_name as usize)?;
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let is_rebind_type = match ELF32_R_TYPE(rela.r_info) {
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R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT
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if self.arch == Arch::OpenRisc => true,
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R_ARM_GLOB_DAT | R_ARM_JUMP_SLOT
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if self.arch == Arch::Arm => true,
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_ =>
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// No associated symbols for other relocation types.
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false,
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};
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if sym_name == name {
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self.update_rela(rela, addr)?
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}
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if is_rebind_type {
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let sym = self.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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let sym_name = self.name_starting_at(sym.st_name as usize)?;
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if sym_name == name {
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self.update_rela(rela, addr)?
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}
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// No associated symbols for other relocation types.
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_ => ()
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}
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}
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Ok(())
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@ -162,16 +194,39 @@ impl<'a> Library<'a> {
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.ok_or("symbol out of bounds of symbol table")?)
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}
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enum RelaType {
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None,
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Relative,
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Lookup,
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};
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let rela_type = match ELF32_R_TYPE(rela.r_info) {
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R_OR1K_NONE if self.arch == Arch::OpenRisc =>
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RelaType::None,
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R_ARM_NONE if self.arch == Arch::Arm =>
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RelaType::None,
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R_OR1K_RELATIVE if self.arch == Arch::OpenRisc =>
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RelaType::Relative,
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R_ARM_RELATIVE if self.arch == Arch::Arm =>
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RelaType::Relative,
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R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT
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if self.arch == Arch::OpenRisc => RelaType::Lookup,
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R_ARM_GLOB_DAT | R_ARM_JUMP_SLOT
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if self.arch == Arch::Arm => RelaType::Lookup,
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_ =>
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return Err("unsupported relocation type")?,
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};
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let value;
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match ELF32_R_TYPE(rela.r_info) {
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R_OR1K_NONE | R_ARM_NONE =>
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match rela_type {
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RelaType::None =>
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return Ok(()),
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R_OR1K_RELATIVE | R_ARM_RELATIVE =>
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RelaType::Relative =>
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value = self.image_off + rela.r_addend as Elf32_Word,
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R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT |
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R_ARM_GLOB_DAT | R_ARM_JUMP_SLOT => {
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RelaType::Lookup => {
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let sym = sym.ok_or("relocation requires an associated symbol")?;
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let sym_name = self.name_starting_at(sym.st_name as usize)?;
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@ -190,9 +245,6 @@ impl<'a> Library<'a> {
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}
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}
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}
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_ =>
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return Err("unsupported relocation type")?,
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}
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self.update_rela(rela, value)
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@ -205,25 +257,12 @@ impl<'a> Library<'a> {
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let ehdr = read_unaligned::<Elf32_Ehdr>(data, 0)
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.map_err(|()| "cannot read ELF header")?;
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const IDENT_OPENRISC: [u8; EI_NIDENT] = [
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ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
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ELFCLASS32, ELFDATA2MSB, EV_CURRENT, ELFOSABI_NONE,
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/* ABI version */ 0, /* padding */ 0, 0, 0, 0, 0, 0, 0
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];
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const IDENT_ARM: [u8; EI_NIDENT] = [
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ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
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ELFCLASS32, ELFDATA2LSB, EV_CURRENT, ELFOSABI_NONE,
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/* ABI version */ 0, /* padding */ 0, 0, 0, 0, 0, 0, 0
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];
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if ehdr.e_type != ET_DYN {
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return Err("not a shared library")?
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}
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if !((ehdr.e_ident == IDENT_OPENRISC && ehdr.e_machine == EM_OPENRISC)
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|| ((ehdr.e_ident == IDENT_ARM && ehdr.e_machine == EM_ARM))) {
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return Err("not for a supported architecture")?
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}
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let arch = Arch::detect(&ehdr)
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.ok_or("not for a supported architecture")?;
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let mut dyn_off = None;
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for i in 0..ehdr.e_phnum {
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@ -324,11 +363,12 @@ impl<'a> Library<'a> {
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let library = Library {
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image_off: image.as_ptr() as Elf32_Word,
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image_sz: image.len(),
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strtab: strtab,
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symtab: symtab,
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pltrel: pltrel,
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strtab,
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symtab,
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pltrel,
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hash_bucket: &hash[..nbucket],
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hash_chain: &hash[nbucket..nbucket + nchain],
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arch,
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};
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// If a borrow exists anywhere, the borrowed memory cannot be mutated except
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