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Support MIPS PIC relocations

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This commit is contained in:
Luke Street
2023-01-21 12:41:41 -05:00
parent 09bbc534bd
commit 8278d5d207
3 changed files with 72 additions and 52 deletions
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85
src/obj/elf.rs
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@@ -1,15 +1,11 @@
use std::{collections::BTreeMap, fs, io::Cursor, path::Path};
use anyhow::{Context, Result};
use anyhow::{anyhow, bail, Context, Result};
use byteorder::{BigEndian, ReadBytesExt};
use cwdemangle::demangle;
use flagset::Flags;
use object::{
elf::{
R_MIPS_26, R_MIPS_HI16, R_MIPS_LO16, R_PPC_ADDR16_HA, R_PPC_ADDR16_HI, R_PPC_ADDR16_LO,
R_PPC_EMB_SDA21, R_PPC_REL14, R_PPC_REL24,
},
Architecture, File, Object, ObjectSection, ObjectSymbol, RelocationKind, RelocationTarget,
elf, Architecture, File, Object, ObjectSection, ObjectSymbol, RelocationKind, RelocationTarget,
SectionIndex, SectionKind, Symbol, SymbolKind, SymbolSection,
};
@@ -207,12 +203,12 @@ fn relocations_by_section(
RelocationKind::Absolute => ObjRelocKind::Absolute,
RelocationKind::Elf(kind) => match arch {
ObjArchitecture::PowerPc => match kind {
R_PPC_ADDR16_LO => ObjRelocKind::PpcAddr16Lo,
R_PPC_ADDR16_HI => ObjRelocKind::PpcAddr16Hi,
R_PPC_ADDR16_HA => ObjRelocKind::PpcAddr16Ha,
R_PPC_REL24 => ObjRelocKind::PpcRel24,
R_PPC_REL14 => ObjRelocKind::PpcRel14,
R_PPC_EMB_SDA21 => ObjRelocKind::PpcEmbSda21,
elf::R_PPC_ADDR16_LO => ObjRelocKind::PpcAddr16Lo,
elf::R_PPC_ADDR16_HI => ObjRelocKind::PpcAddr16Hi,
elf::R_PPC_ADDR16_HA => ObjRelocKind::PpcAddr16Ha,
elf::R_PPC_REL24 => ObjRelocKind::PpcRel24,
elf::R_PPC_REL14 => ObjRelocKind::PpcRel14,
elf::R_PPC_EMB_SDA21 => ObjRelocKind::PpcEmbSda21,
_ => {
return Err(anyhow::Error::msg(format!(
"Unhandled PPC relocation type: {kind}"
@@ -220,14 +216,14 @@ fn relocations_by_section(
}
},
ObjArchitecture::Mips => match kind {
R_MIPS_26 => ObjRelocKind::Mips26,
R_MIPS_HI16 => ObjRelocKind::MipsHi16,
R_MIPS_LO16 => ObjRelocKind::MipsLo16,
_ => {
return Err(anyhow::Error::msg(format!(
"Unhandled MIPS relocation type: {kind}"
)))
}
elf::R_MIPS_26 => ObjRelocKind::Mips26,
elf::R_MIPS_HI16 => ObjRelocKind::MipsHi16,
elf::R_MIPS_LO16 => ObjRelocKind::MipsLo16,
elf::R_MIPS_GOT16 => ObjRelocKind::MipsGot16,
elf::R_MIPS_CALL16 => ObjRelocKind::MipsCall16,
elf::R_MIPS_GPREL16 => ObjRelocKind::MipsGpRel16,
elf::R_MIPS_GPREL32 => ObjRelocKind::MipsGpRel32,
_ => bail!("Unhandled MIPS relocation type: {kind}"),
},
},
_ => {
@@ -244,37 +240,36 @@ fn relocations_by_section(
}
_ => None,
};
// println!("Reloc: {:?}, symbol: {:?}", reloc, symbol);
let addend = if reloc.has_implicit_addend() {
let addend = u32::from_be_bytes(
section.data[address as usize..address as usize + 4].try_into()?,
);
match kind {
ObjRelocKind::Absolute => addend as i64,
ObjRelocKind::MipsHi16 => ((addend & 0x0000FFFF) << 16) as i16 as i64,
ObjRelocKind::MipsLo16
| ObjRelocKind::MipsGot16
| ObjRelocKind::MipsCall16
| ObjRelocKind::MipsGpRel16 => (addend & 0x0000FFFF) as i16 as i64,
ObjRelocKind::MipsGpRel32 => addend as i32 as i64,
ObjRelocKind::Mips26 => ((addend & 0x03FFFFFF) << 2) as i64,
_ => bail!("Unsupported implicit relocation {kind:?}"),
}
} else {
reloc.addend()
};
// println!("Reloc: {reloc:?}, symbol: {symbol:?}, addend: {addend:#X}");
let target = match symbol.kind() {
SymbolKind::Text | SymbolKind::Data | SymbolKind::Label | SymbolKind::Unknown => {
to_obj_symbol(obj_file, &symbol, reloc.addend())
to_obj_symbol(obj_file, &symbol, addend)
}
SymbolKind::Section => {
let addend = if reloc.has_implicit_addend() {
let addend = u32::from_be_bytes(
section.data[address as usize..address as usize + 4].try_into()?,
);
match kind {
ObjRelocKind::Absolute => addend,
ObjRelocKind::MipsHi16 | ObjRelocKind::MipsLo16 => addend & 0x0000FFFF,
ObjRelocKind::Mips26 => (addend & 0x03FFFFFF) * 4,
_ => todo!(),
}
} else {
let addend = reloc.addend();
if addend < 0 {
return Err(anyhow::Error::msg(format!(
"Negative addend in section reloc: {addend}"
)));
}
addend as u32
};
if addend < 0 {
return Err(anyhow::Error::msg(format!("Negative addend in reloc: {addend}")));
}
find_section_symbol(obj_file, &symbol, addend as u64)
}
_ => Err(anyhow::Error::msg(format!(
"Unhandled relocation symbol type {:?}",
symbol.kind()
))),
kind => Err(anyhow!("Unhandled relocation symbol type {kind:?}")),
}?;
relocations.push(ObjReloc { kind, address, target, target_section });
}