Browse Source

add nac3ld

issue-136
occheung 6 months ago
parent
commit
a96371145d
  1. 7
      Cargo.lock
  2. 1
      Cargo.toml
  3. 8
      nac3ld/Cargo.toml
  4. 365
      nac3ld/src/dwarf.rs
  5. 2893
      nac3ld/src/elf.rs
  6. 1492
      nac3ld/src/lib.rs

7
Cargo.lock generated

@ -521,6 +521,13 @@ dependencies = [
"test-case",
]
[[package]]
name = "nac3ld"
version = "0.1.0"
dependencies = [
"byteorder",
]
[[package]]
name = "nac3parser"
version = "0.1.2"

1
Cargo.toml

@ -1,5 +1,6 @@
[workspace]
members = [
"nac3ld",
"nac3ast",
"nac3parser",
"nac3core",

8
nac3ld/Cargo.toml

@ -0,0 +1,8 @@
[package]
name = "nac3ld"
version = "0.1.0"
authors = ["M-Labs"]
edition = "2018"
[dependencies]
byteorder = { version = "1.0", default-features = false }

365
nac3ld/src/dwarf.rs

@ -0,0 +1,365 @@
#![allow(non_camel_case_types, non_upper_case_globals)]
use std::mem;
pub const DW_EH_PE_omit: u8 = 0xFF;
pub const DW_EH_PE_absptr: u8 = 0x00;
pub const DW_EH_PE_uleb128: u8 = 0x01;
pub const DW_EH_PE_udata2: u8 = 0x02;
pub const DW_EH_PE_udata4: u8 = 0x03;
pub const DW_EH_PE_udata8: u8 = 0x04;
pub const DW_EH_PE_sleb128: u8 = 0x09;
pub const DW_EH_PE_sdata2: u8 = 0x0A;
pub const DW_EH_PE_sdata4: u8 = 0x0B;
pub const DW_EH_PE_sdata8: u8 = 0x0C;
pub const DW_EH_PE_pcrel: u8 = 0x10;
pub const DW_EH_PE_textrel: u8 = 0x20;
pub const DW_EH_PE_datarel: u8 = 0x30;
pub const DW_EH_PE_funcrel: u8 = 0x40;
pub const DW_EH_PE_aligned: u8 = 0x50;
pub const DW_EH_PE_indirect: u8 = 0x80;
pub struct DwarfReader {
pub ptr: *const u8,
pub virt_addr: u32,
}
#[repr(C, packed)]
struct Unaligned<T>(T);
impl DwarfReader {
pub fn new(ptr: *const u8, virt_addr: u32) -> DwarfReader {
DwarfReader { ptr, virt_addr }
}
// DWARF streams are packed, so e.g., a u32 would not necessarily be aligned
// on a 4-byte boundary. This may cause problems on platforms with strict
// alignment requirements. By wrapping data in a "packed" struct, we are
// telling the backend to generate "misalignment-safe" code.
pub unsafe fn read<T: Copy>(&mut self) -> T {
let Unaligned(result) = *(self.ptr as *const Unaligned<T>);
let addr_increment = mem::size_of::<T>();
self.ptr = self.ptr.add(addr_increment);
self.virt_addr += addr_increment as u32;
result
}
pub unsafe fn offset(&mut self, offset: i32) {
self.ptr = self.ptr.offset(offset as isize);
self.virt_addr = self.virt_addr.wrapping_add(offset as u32);
}
// ULEB128 and SLEB128 encodings are defined in Section 7.6 - "Variable
// Length Data".
pub unsafe fn read_uleb128(&mut self) -> u64 {
let mut shift: usize = 0;
let mut result: u64 = 0;
let mut byte: u8;
loop {
byte = self.read::<u8>();
result |= ((byte & 0x7F) as u64) << shift;
shift += 7;
if byte & 0x80 == 0 {
break;
}
}
result
}
pub unsafe fn read_sleb128(&mut self) -> i64 {
let mut shift: u32 = 0;
let mut result: u64 = 0;
let mut byte: u8;
loop {
byte = self.read::<u8>();
result |= ((byte & 0x7F) as u64) << shift;
shift += 7;
if byte & 0x80 == 0 {
break;
}
}
// sign-extend
if shift < u64::BITS && (byte & 0x40) != 0 {
result |= (!0 as u64) << shift;
}
result as i64
}
}
pub struct DwarfWriter {
pub ptr: *mut u8,
}
impl DwarfWriter {
pub fn new(ptr: *mut u8) -> DwarfWriter {
DwarfWriter { ptr }
}
pub unsafe fn write<T: Copy>(&mut self, data: T) {
*(self.ptr as *mut Unaligned<T>) = Unaligned(data);
self.ptr = self.ptr.add(mem::size_of::<T>());
}
}
unsafe fn read_encoded_pointer(reader: &mut DwarfReader, encoding: u8) -> Result<usize, ()> {
if encoding == DW_EH_PE_omit {
return Err(());
}
// DW_EH_PE_aligned implies it's an absolute pointer value
if encoding == DW_EH_PE_aligned {
reader.ptr = round_up(reader.ptr as usize, mem::size_of::<usize>())? as *const u8;
return Ok(reader.read::<usize>());
}
match encoding & 0x0F {
DW_EH_PE_absptr => Ok(reader.read::<usize>()),
DW_EH_PE_uleb128 => Ok(reader.read_uleb128() as usize),
DW_EH_PE_udata2 => Ok(reader.read::<u16>() as usize),
DW_EH_PE_udata4 => Ok(reader.read::<u32>() as usize),
DW_EH_PE_udata8 => Ok(reader.read::<u64>() as usize),
DW_EH_PE_sleb128 => Ok(reader.read_sleb128() as usize),
DW_EH_PE_sdata2 => Ok(reader.read::<i16>() as usize),
DW_EH_PE_sdata4 => Ok(reader.read::<i32>() as usize),
DW_EH_PE_sdata8 => Ok(reader.read::<i64>() as usize),
_ => Err(()),
}
}
unsafe fn read_encoded_pointer_with_pc(
reader: &mut DwarfReader,
encoding: u8,
) -> Result<usize, ()> {
let entry_virt_addr = reader.virt_addr;
let mut result = read_encoded_pointer(reader, encoding)?;
// DW_EH_PE_aligned implies it's an absolute pointer value
if encoding == DW_EH_PE_aligned {
return Ok(result);
}
result = match encoding & 0x70 {
DW_EH_PE_pcrel => result.wrapping_add(entry_virt_addr as usize),
// .eh_frame normally would not have these kinds of relocations
// These would not be supported by a dedicated linker relocation schemes for RISC-V
DW_EH_PE_textrel | DW_EH_PE_datarel | DW_EH_PE_funcrel | DW_EH_PE_aligned => {
unimplemented!()
}
// Other values should be impossible
_ => unreachable!(),
};
if encoding & DW_EH_PE_indirect != 0 {
// There should not be a need for indirect addressing, as assembly code from
// the dynamic library should not be freely moved relative to the EH frame.
unreachable!()
}
Ok(result)
}
#[inline]
fn round_up(unrounded: usize, align: usize) -> Result<usize, ()> {
if align.is_power_of_two() {
Ok((unrounded + align - 1) & !(align - 1))
} else {
Err(())
}
}
// Minimalistic structure to store everything needed for parsing FDEs to synthesize
// .eh_frame_hdr section. Since we are only linking 1 object file, there should only be 1 call
// frame information (CFI) record, so there should be only 1 common information entry (CIE).
// So the class parses the only CIE on init, cache the encoding info, then parse the FDE on
// iterations based on the cached encoding format.
pub struct EH_Frame {
// It refers to the augmentation data that corresponds to 'R' in the augmentation string
pub fde_pointer_encoding: u8,
pub fde_reader: DwarfReader,
pub fde_sz: usize,
}
impl EH_Frame {
pub unsafe fn new(eh_frame_slice: &[u8], eh_frame_addr: u32) -> Result<EH_Frame, ()> {
let mut cie_reader = DwarfReader::new(eh_frame_slice.as_ptr(), eh_frame_addr);
let eh_frame_size = eh_frame_slice.len();
let length = cie_reader.read::<u32>();
let fde_reader = match length {
// eh_frame with 0 lengths means the CIE is terminated
// while length == u32::MAX means that the length is only representable with 64 bits,
// which does not make sense in a system with 32-bit address.
0 | 0xFFFFFFFF => unimplemented!(),
_ => {
let mut fde_reader = DwarfReader::new(cie_reader.ptr, cie_reader.virt_addr);
fde_reader.offset(length as i32);
fde_reader
}
};
let fde_sz = eh_frame_size - mem::size_of::<u32>() - length as usize;
// Routine check on the .eh_frame well-formness, in terms of CIE ID & Version args.
assert_eq!(cie_reader.read::<u32>(), 0);
assert_eq!(cie_reader.read::<u8>(), 1);
// Parse augmentation string
// The first character must be 'z', there is no way to proceed otherwise
assert_eq!(cie_reader.read::<u8>(), b'z');
// Establish a pointer that skips ahead of the string
// Skip code/data alignment factors & return address register along the way as well
// We only tackle the case where 'z' and 'R' are part of the augmentation string, otherwise
// we cannot get the addresses to make .eh_frame_hdr
let mut aug_data_reader = DwarfReader::new(cie_reader.ptr, cie_reader.virt_addr);
let mut aug_str_len = 0;
loop {
if aug_data_reader.read::<u8>() == b'\0' {
break;
}
aug_str_len += 1;
}
if aug_str_len == 0 {
unimplemented!();
}
aug_data_reader.read_uleb128(); // Code alignment factor
aug_data_reader.read_sleb128(); // Data alignment factor
aug_data_reader.read_uleb128(); // Return address register
aug_data_reader.read_uleb128(); // Augmentation data length
let mut fde_pointer_encoding = DW_EH_PE_omit;
for _ in 0..aug_str_len {
match cie_reader.read::<u8>() {
b'L' => {
aug_data_reader.read::<u8>();
}
b'P' => {
let encoding = aug_data_reader.read::<u8>();
read_encoded_pointer(&mut aug_data_reader, encoding)?;
}
b'R' => {
fde_pointer_encoding = aug_data_reader.read::<u8>();
}
// Other characters are not supported
_ => unimplemented!(),
}
}
assert_ne!(fde_pointer_encoding, DW_EH_PE_omit);
Ok(EH_Frame { fde_pointer_encoding, fde_reader, fde_sz })
}
pub unsafe fn iterate_fde(&self, callback: &mut dyn FnMut(u32, u32)) -> Result<(), ()> {
// Parse each FDE to obtain the starting address that the FDE applies to
// Send the FDE offset and the mentioned address to a callback that write up the
// .eh_frame_hdr section
let mut remaining_len = self.fde_sz;
let mut reader = DwarfReader::new(self.fde_reader.ptr, self.fde_reader.virt_addr);
loop {
if remaining_len == 0 {
break;
}
let fde_virt_addr = reader.virt_addr;
let length = match reader.read::<u32>() {
0 | 0xFFFFFFFF => unimplemented!(),
other => other,
};
// Remove the length of the header and the content from the counter
remaining_len -= length as usize + mem::size_of::<u32>();
let mut next_fde_reader = DwarfReader::new(reader.ptr, reader.virt_addr);
next_fde_reader.offset(length as i32);
// Skip CIE pointer offset
reader.read::<u32>();
// Parse PC Begin using the encoding scheme mentioned in the CIE
let pc_begin = read_encoded_pointer_with_pc(&mut reader, self.fde_pointer_encoding)?;
callback(pc_begin as u32, fde_virt_addr);
reader = next_fde_reader;
}
Ok(())
}
}
pub struct EH_Frame_Hdr {
fde_writer: DwarfWriter,
fde_count_ptr: *mut u8,
eh_frame_hdr_addr: u32,
fdes: Vec<(u32, u32)>,
}
impl EH_Frame_Hdr {
// Create a EH_Frame_Hdr object, and write out the fixed fields of .eh_frame_hdr to memory
// eh_frame_ptr_enc will be 0x1B (PC-relative, 4 bytes)
// table_enc will be 0x3B (Relative to the start of .eh_frame_hdr, 4 bytes)
// Load address is not known at this point.
pub unsafe fn new(
eh_frame_hdr_slice: &mut [u8],
eh_frame_hdr_addr: u32,
eh_frame_addr: u32,
) -> EH_Frame_Hdr {
let mut writer = DwarfWriter::new(eh_frame_hdr_slice.as_mut_ptr());
writer.write::<u8>(1);
writer.write::<u8>(0x1B);
writer.write::<u8>(0x03);
writer.write::<u8>(0x3B);
let eh_frame_offset =
(eh_frame_addr).wrapping_sub(eh_frame_hdr_addr + ((mem::size_of::<u8>() as u32) * 4));
writer.write(eh_frame_offset);
let fde_count_ptr = writer.ptr;
writer.write::<u32>(0);
EH_Frame_Hdr { fde_writer: writer, fde_count_ptr, eh_frame_hdr_addr, fdes: Vec::new() }
}
pub unsafe fn add_fde(&mut self, init_loc: u32, addr: u32) {
self.fdes.push((
init_loc.wrapping_sub(self.eh_frame_hdr_addr),
addr.wrapping_sub(self.eh_frame_hdr_addr),
));
}
pub unsafe fn finalize_fde(mut self) {
self.fdes
.sort_by(|(left_init_loc, _), (right_init_loc, _)| left_init_loc.cmp(right_init_loc));
for (init_loc, addr) in &self.fdes {
self.fde_writer.write(init_loc);
self.fde_writer.write(addr);
}
let mut fde_count_writer = DwarfWriter::new(self.fde_count_ptr);
fde_count_writer.write::<u32>(self.fdes.len() as u32);
}
pub unsafe fn size_from_eh_frame(eh_frame: &[u8]) -> usize {
// The virtual address of the EH frame does no matter in this case
// Calculation of size does not involve modifying any headers
let mut reader = DwarfReader::new(eh_frame.as_ptr(), 0);
let end_addr = eh_frame.as_ptr() as usize + eh_frame.len();
let mut fde_count = 0;
while (reader.ptr as usize) < end_addr {
// The original length field should be able to hold the entire value.
// The device memory space is limited to 32-bits addresses anyway.
let entry_length = reader.read::<u32>();
let next_ptr = reader.ptr.offset(entry_length as isize);
if entry_length == 0 || entry_length == 0xFFFFFFFF {
unimplemented!()
}
if reader.read::<u32>() != 0 {
fde_count += 1;
}
reader.ptr = next_ptr;
}
12 + fde_count * 8
}
}

2893
nac3ld/src/elf.rs

File diff suppressed because it is too large Load Diff

1492
nac3ld/src/lib.rs

File diff suppressed because it is too large Load Diff
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