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PPC: Detect unpooled string literal references #188

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Merged
merged 2 commits into from
Apr 17, 2025
Merged

PPC: Detect unpooled string literal references #188

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16f65d4
Update openssl and tokio for Cargo deny
LagoLunatic Apr 13, 2025
2432069
PPC: Detect unpooled string literal references
LagoLunatic Apr 13, 2025
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22 changes: 11 additions & 11 deletions Cargo.lock
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8 changes: 7 additions & 1 deletion objdiff-core/src/arch/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -247,7 +247,13 @@ pub trait Arch: Send + Sync + Debug {
SymbolFlagSet::default()
}

fn guess_data_type(&self, _resolved: ResolvedInstructionRef) -> Option<DataType> { None }
fn guess_data_type(
&self,
_resolved: ResolvedInstructionRef,
_bytes: &[u8],
) -> Option<DataType> {
None
}

fn symbol_hover(&self, _obj: &Object, _symbol_index: usize) -> Vec<HoverItem> { Vec::new() }

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13 changes: 11 additions & 2 deletions objdiff-core/src/arch/ppc.rs
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Expand Up @@ -221,12 +221,21 @@ impl Arch for ArchPpc {
}
}

fn guess_data_type(&self, resolved: ResolvedInstructionRef) -> Option<DataType> {
fn guess_data_type(&self, resolved: ResolvedInstructionRef, bytes: &[u8]) -> Option<DataType> {
if resolved.relocation.is_some_and(|r| r.symbol.name.starts_with("@stringBase")) {
// Pooled string.
return Some(DataType::String);
}
let opcode = ppc750cl::Opcode::from(resolved.ins_ref.opcode as u8);
guess_data_type_from_load_store_inst_op(opcode)
if let Some(ty) = guess_data_type_from_load_store_inst_op(opcode) {
// Numeric type.
return Some(ty);
}
if bytes.len() >= 2 && bytes.iter().position(|&c| c == b'\0') == Some(bytes.len() - 1) {
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Suggested change
if bytes.len() >= 2 && bytes.iter().position(|&c| c == b'\0') == Some(bytes.len() - 1) {
if bytes.len() >= 2 && bytes.iter().position(|&c| c == b'\0') == bytes.last() {

I think this should work

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last would return the last byte in the slice, I think? This is comparing to the last index (len-1), not the value, since all the values were already read inside the loop.

The compiler also doesn't like last for some reason:

can't compare `std::option::Option<usize>` with `std::option::Option<&u8>`
the trait `PartialEq<std::option::Option<&u8>>` is not implemented for `std::option::Option<usize>`
but trait `PartialEq<deranged::OptionRangedUsize<_, _>>` is implemented for it
for that trait implementation, expected `deranged::OptionRangedUsize<_, _>`, found `std::option::Option<&u8>`

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I think my brain was melted by C++ iterators, nevermind

// It may be an unpooled string if the symbol contains exactly one null byte at the end of the symbol.
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Doesn't have to be this PR, just thinking aloud, this logic could easily live in common arch code.

return Some(DataType::String);
}
None
}

fn symbol_hover(&self, _obj: &Object, symbol_index: usize) -> Vec<HoverItem> {
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1 change: 1 addition & 0 deletions objdiff-core/src/diff/code.rs
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Expand Up @@ -330,6 +330,7 @@ fn reloc_eq(
|| address_eq(left_reloc, right_reloc))
&& (diff_config.function_reloc_diffs == FunctionRelocDiffs::NameAddress
|| left_reloc.symbol.kind != SymbolKind::Object
|| right_reloc.symbol.size == 0 // Likely a pool symbol like ...data, don't treat this as a diff
|| display_ins_data_literals(left_obj, left_ins)
== display_ins_data_literals(right_obj, right_ins))
}
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7 changes: 4 additions & 3 deletions objdiff-core/src/diff/display.rs
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Expand Up @@ -564,7 +564,8 @@ pub fn instruction_hover(
if let Some(reloc) = resolved.relocation {
out.push(HoverItem::Separator);
out.append(&mut relocation_hover(obj, reloc, None));
if let Some(ty) = obj.arch.guess_data_type(resolved) {
let bytes = obj.symbol_data(reloc.relocation.target_symbol).unwrap_or(&[]);
if let Some(ty) = obj.arch.guess_data_type(resolved, bytes) {
let literals = display_ins_data_literals(obj, resolved);
if !literals.is_empty() {
out.push(HoverItem::Separator);
Expand Down Expand Up @@ -758,7 +759,7 @@ pub fn display_ins_data_labels(obj: &Object, resolved: ResolvedInstructionRef) -
};
let bytes = &data[reloc.relocation.addend as usize..];
obj.arch
.guess_data_type(resolved)
.guess_data_type(resolved, bytes)
.map(|ty| ty.display_labels(obj.endianness, bytes))
.unwrap_or_default()
}
Expand All @@ -775,7 +776,7 @@ pub fn display_ins_data_literals(obj: &Object, resolved: ResolvedInstructionRef)
};
let bytes = &data[reloc.relocation.addend as usize..];
obj.arch
.guess_data_type(resolved)
.guess_data_type(resolved, bytes)
.map(|ty| ty.display_literals(obj.endianness, bytes))
.unwrap_or_default()
}
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