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Support Aarch64Call relocations for Mach-O #465

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merged 2 commits into from Oct 4, 2022
Merged

Support Aarch64Call relocations for Mach-O #465

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6517a8b
Support Aarch64Call relocations for Mach-O
nathanwhit Sep 19, 2022
76877fe
Move Aarch64Call special handling to macho module
nathanwhit Sep 21, 2022
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28 changes: 27 additions & 1 deletion src/write/macho.rs
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Expand Up @@ -175,11 +175,17 @@ impl<'a> Object<'a> {

pub(crate) fn macho_fixup_relocation(&mut self, mut relocation: &mut Relocation) -> i64 {
let constant = match relocation.kind {
// AArch64Call relocations have special handling for the addend, so don't adjust it
RelocationKind::Relative if relocation.encoding == RelocationEncoding::AArch64Call => 0,
RelocationKind::Relative
| RelocationKind::GotRelative
| RelocationKind::PltRelative => relocation.addend + 4,
_ => relocation.addend,
};
// Aarch64 relocs of these sizes act as if they are double-word length
if self.architecture == Architecture::Aarch64 && matches!(relocation.size, 12 | 21 | 26) {
relocation.size = 32;
}
relocation.addend -= constant;
constant
}
Expand Down Expand Up @@ -534,7 +540,7 @@ impl<'a> Object<'a> {
debug_assert_eq!(section_offsets[index].reloc_offset, buffer.len());
for reloc in &section.relocations {
let r_extern;
let r_symbolnum;
let mut r_symbolnum;
let symbol = &self.symbols[reloc.symbol.0];
if symbol.kind == SymbolKind::Section {
r_symbolnum = section_offsets[symbol.section.id().unwrap().0].index as u32;
Expand Down Expand Up @@ -590,6 +596,26 @@ impl<'a> Object<'a> {
(RelocationKind::Absolute, RelocationEncoding::Generic, 0) => {
(false, macho::ARM64_RELOC_UNSIGNED)
}
(RelocationKind::Relative, RelocationEncoding::AArch64Call, 0) => {
(true, macho::ARM64_RELOC_BRANCH26)
}
// Non-zero addend, so we have to encode the addend separately
(RelocationKind::Relative, RelocationEncoding::AArch64Call, value) => {
// first emit the BR26 relocation
let reloc_info = macho::RelocationInfo {
r_address: reloc.offset as u32,
r_symbolnum,
r_pcrel: true,
r_length,
r_extern: true,
r_type: macho::ARM64_RELOC_BRANCH26,
};
buffer.write(&reloc_info.relocation(endian));

// set up a separate relocation for the addend
r_symbolnum = value as u32;
(false, macho::ARM64_RELOC_ADDEND)
}
(
RelocationKind::MachO { value, relative },
RelocationEncoding::Generic,
Expand Down