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MIPS relocation pairing, '$' prefix option & fixes

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Implements MIPS relocation pairing logic.
New option for "Register '$' prefix", off by default.
Fixes various regressions introduced by refactoring.

Resolves #122
Resolves #156
This commit is contained in:
Luke Street
2025-03-03 17:14:32 -07:00
parent 80e939653a
commit 6ed07bfaf1
10 changed files with 2333 additions and 62 deletions
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114
objdiff-core/src/obj/read.rs
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@@ -263,7 +263,7 @@ const LOW_PRIORITY_SYMBOLS: &[&str] =
fn best_symbol<'r, 'data, 'file>(
symbols: &'r [object::Symbol<'data, 'file>],
address: u64,
) -> Option<object::SymbolIndex> {
) -> Option<(object::SymbolIndex, u64)> {
let mut closest_symbol_index = match symbols.binary_search_by_key(&address, |s| s.address()) {
Ok(index) => Some(index),
Err(index) => index.checked_sub(1),
@@ -297,18 +297,31 @@ fn best_symbol<'r, 'data, 'file>(
best_symbol = Some(symbol);
}
}
best_symbol.map(|s| s.index())
best_symbol.map(|s| (s.index(), s.address()))
}
fn map_relocations(
fn map_section_relocations(
arch: &dyn Arch,
obj_file: &object::File,
obj_section: &object::Section,
symbol_indices: &[usize],
ordered_symbols: &[Vec<object::Symbol>],
) -> Result<Vec<Relocation>> {
let mut relocations = Vec::<Relocation>::with_capacity(obj_section.relocations().count());
let mut ordered_symbols = None;
for (address, reloc) in obj_section.relocations() {
let flags = match reloc.flags() {
object::RelocationFlags::Elf { r_type } => RelocationFlags::Elf(r_type),
object::RelocationFlags::Coff { typ } => RelocationFlags::Coff(typ),
flags => {
bail!("Unhandled relocation flags: {:?}", flags);
}
};
// TODO validate reloc here?
let mut addend = if reloc.has_implicit_addend() {
arch.implcit_addend(obj_file, obj_section, address, &reloc, flags)?
} else {
reloc.addend()
};
let target_symbol = match reloc.target() {
object::RelocationTarget::Symbol(idx) => {
if idx.0 == u32::MAX as usize {
@@ -323,24 +336,16 @@ fn map_relocations(
{
let section_index =
section_symbol.section_index().context("Section symbol without section")?;
let ordered_symbols = ordered_symbols.get_or_insert_with(|| {
let mut vec = obj_file
.symbols()
.filter(|s| {
s.section_index() == Some(section_index)
&& s.kind() != object::SymbolKind::Section
})
.collect::<Vec<_>>();
vec.sort_by(|a, b| {
a.address().cmp(&b.address()).then(a.size().cmp(&b.size()))
});
vec
});
best_symbol(
ordered_symbols,
section_symbol.address().wrapping_add_signed(reloc.addend()),
)
.unwrap_or(idx)
let target_address = section_symbol.address().wrapping_add_signed(addend);
if let Some((new_idx, addr)) = ordered_symbols
.get(section_index.0)
.and_then(|symbols| best_symbol(symbols, target_address))
{
addend = target_address.wrapping_sub(addr) as i64;
new_idx
} else {
idx
}
} else {
idx
};
@@ -359,24 +364,55 @@ fn map_relocations(
}
_ => bail!("Unhandled relocation target: {:?}", reloc.target()),
};
let flags = match reloc.flags() {
object::RelocationFlags::Elf { r_type } => RelocationFlags::Elf(r_type),
object::RelocationFlags::Coff { typ } => RelocationFlags::Coff(typ),
flags => {
bail!("Unhandled relocation flags: {:?}", flags);
}
};
// TODO validate reloc here?
let addend = if reloc.has_implicit_addend() {
arch.implcit_addend(obj_file, obj_section, address, &reloc, flags)?
} else {
reloc.addend()
};
relocations.push(Relocation { address, flags, target_symbol, addend });
}
relocations.sort_by_key(|r| r.address);
Ok(relocations)
}
fn map_relocations(
arch: &dyn Arch,
obj_file: &object::File,
sections: &mut [Section],
section_indices: &[usize],
symbol_indices: &[usize],
) -> Result<()> {
// Generate a list of symbols for each section
let mut ordered_symbols =
Vec::<Vec<object::Symbol>>::with_capacity(obj_file.sections().count() + 1);
for symbol in obj_file.symbols() {
let Some(section_index) = symbol.section_index() else {
continue;
};
if symbol.kind() == object::SymbolKind::Section {
continue;
}
if section_index.0 >= ordered_symbols.len() {
ordered_symbols.resize_with(section_index.0 + 1, Vec::new);
}
ordered_symbols[section_index.0].push(symbol);
}
// Sort symbols by address and size
for vec in &mut ordered_symbols {
vec.sort_by(|a, b| a.address().cmp(&b.address()).then(a.size().cmp(&b.size())));
}
// Map relocations for each section. Section-relative relocations use the ordered symbols list
// to find a better target symbol, if available.
for obj_section in obj_file.sections() {
let section = &mut sections[section_indices[obj_section.index().0]];
if section.kind != SectionKind::Unknown {
section.relocations = map_section_relocations(
arch,
obj_file,
&obj_section,
symbol_indices,
&ordered_symbols,
)?;
}
}
Ok(())
}
fn parse_line_info(
obj_file: &object::File,
sections: &mut [Section],
@@ -767,13 +803,7 @@ pub fn parse(data: &[u8], config: &DiffObjConfig) -> Result<Object> {
map_sections(arch.as_ref(), &obj_file, split_meta.as_ref())?;
let (mut symbols, symbol_indices) =
map_symbols(arch.as_ref(), &obj_file, &sections, &section_indices, split_meta.as_ref())?;
for obj_section in obj_file.sections() {
let section = &mut sections[section_indices[obj_section.index().0]];
if section.kind != SectionKind::Unknown {
section.relocations =
map_relocations(arch.as_ref(), &obj_file, &obj_section, &symbol_indices)?;
}
}
map_relocations(arch.as_ref(), &obj_file, &mut sections, &section_indices, &symbol_indices)?;
parse_line_info(&obj_file, &mut sections, &section_indices, data)?;
if config.combine_data_sections || config.combine_text_sections {
combine_sections(&mut sections, &mut symbols, config)?;