Noratrieb/uwuwind
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This commit is contained in:
nora 2025-10-26 20:14:39 +01:00
parent ba5e53eea6
commit c0cf3786f4
6 changed files with 171 additions and 23 deletions
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98
src/dwarf/divination.rs
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@ -43,6 +43,7 @@ struct EhFrameHeader {
eh_frame_ptr_enc: Encoding,
fde_count_enc: Encoding,
table_enc: Encoding,
rest: (),
}
#[instrument]
@ -93,9 +94,9 @@ pub(crate) fn eh_frame(addr: Addr) -> Option<*const u8> {
trace!("eh_frame_hdr: {:?}", header);
let (read_size, eh_frame_ptr) = read_encoded(ptr, header.eh_frame_ptr_enc);
let (read_size, eh_frame_ptr) = read_encoded(ptr, header.eh_frame_ptr_enc, None);
let ptr = ptr.add(read_size);
let (_read_size, fde_count) = read_encoded(ptr, header.fde_count_enc);
let (_read_size, fde_count) = read_encoded(ptr, header.fde_count_enc, None);
trace!("eh_frame: {eh_frame_ptr:?}");
trace!("fde_count: {fde_count:?}");
@ -108,3 +109,96 @@ pub(crate) fn eh_frame(addr: Addr) -> Option<*const u8> {
Some(eh_frame_ptr as *const u8)
}
}
#[instrument]
pub(crate) fn frame_info(addr: Addr) -> Option<()> {
unsafe {
let header_ptr = eh_frame_hdr_ptr(addr)?;
let eh_frame_header_addr = header_ptr.addr();
let header = header_ptr.read();
let ptr = (&raw const (*header_ptr).rest).cast::<u8>();
let (eh_frame_ptr_size, eh_frame_ptr) = read_encoded(ptr, header.eh_frame_ptr_enc, None);
let ptr = ptr.add(eh_frame_ptr_size);
let (fde_count_size, fde_count) =
read_encoded(ptr, header.fde_count_enc, Some(eh_frame_ptr));
trace!(?header.table_enc);
let table_ptr = ptr.add(fde_count_size);
let mut walk_table_ptr = table_ptr;
for i in 0..fde_count {
let (read, initial_loc) =
read_encoded(walk_table_ptr, header.table_enc, Some(eh_frame_header_addr));
walk_table_ptr = walk_table_ptr.add(read);
let (read, address) =
read_encoded(walk_table_ptr, header.table_enc, Some(eh_frame_header_addr));
walk_table_ptr = walk_table_ptr.add(read);
trace!(idx = ?i, "eh_frame_hdr table initial_loc={initial_loc:x} address={address:x}");
}
let table_half_entry_size = header.table_enc.size();
let mut base = 0;
let mut len = fde_count;
let found_fde;
loop {
if len == 1 {
found_fde = Some(base);
break;
}
let mid = base + len / 2;
let mid_ptr = table_ptr.byte_add(mid * table_half_entry_size * 2);
let (_, value) = read_encoded(mid_ptr, header.table_enc, Some(eh_frame_header_addr));
debug!(
?base,
?len,
?mid,
"binary searching for {addr:?}: {value:x}"
);
match addr.addr().cmp(&value) {
core::cmp::Ordering::Less => {
len = mid - base;
}
core::cmp::Ordering::Equal => {
found_fde = Some(mid);
break;
}
core::cmp::Ordering::Greater => {
len = len - (mid - base);
base = mid;
}
}
}
debug!("found FDE idx in binary search {found_fde:?}");
let fde_table_ptr = table_ptr.byte_add(found_fde.unwrap() * table_half_entry_size * 2);
let (_, fde_address) = read_encoded(
fde_table_ptr.byte_add(table_half_entry_size),
header.table_enc,
Some(eh_frame_header_addr),
);
trace!("found FDE at address {fde_address:x}");
let fde_ptr = core::ptr::with_exposed_provenance::<u8>(fde_address);
fde_ptr.read_volatile();
trace!("ptr is valid");
trace!("FDE offset to .eh_frame: {:x}", fde_ptr.addr() - (eh_frame_ptr));
let fde = crate::dwarf::parse::parse_fde_from_ptr(fde_ptr, eh_frame_ptr).unwrap();
todo!()
}
}