artiq-zynq/libdyld/src/reloc.rs

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Rust
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2020-04-30 04:01:12 +08:00
use alloc::string::String;
use log::{debug, trace};
use super::{
Arch,
elf::*,
Error,
image::{DynamicSection, Image},
};
pub trait Relocatable {
fn offset(&self) -> usize;
fn type_info(&self) -> u8;
fn sym_info(&self) -> u32;
fn addend(&self, image: &Image) -> i32;
}
impl Relocatable for Elf32_Rel {
fn offset(&self) -> usize {
self.r_offset as usize
}
fn type_info(&self) -> u8 {
ELF32_R_TYPE(self.r_info)
}
fn sym_info(&self) -> u32 {
ELF32_R_SYM(self.r_info)
}
fn addend(&self, image: &Image) -> i32 {
*image.get_ref(self.offset()).unwrap()
}
}
impl Relocatable for Elf32_Rela {
fn offset(&self) -> usize {
self.r_offset as usize
}
fn type_info(&self) -> u8 {
ELF32_R_TYPE(self.r_info)
}
fn sym_info(&self) -> u32 {
ELF32_R_SYM(self.r_info)
}
fn addend(&self, _: &Image) -> i32 {
self.r_addend
}
}
#[derive(Clone, Copy, Debug)]
enum RelType {
None,
Relative,
Lookup,
}
impl RelType {
pub fn new(arch: Arch, type_info: u8) -> Option<Self> {
match type_info {
R_OR1K_NONE if arch == Arch::OpenRisc =>
Some(RelType::None),
R_ARM_NONE if arch == Arch::Arm =>
Some(RelType::None),
R_OR1K_RELATIVE if arch == Arch::OpenRisc =>
Some(RelType::Relative),
R_ARM_RELATIVE if arch == Arch::Arm =>
Some(RelType::Relative),
R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT
if arch == Arch::OpenRisc => Some(RelType::Lookup),
R_ARM_GLOB_DAT | R_ARM_JUMP_SLOT
if arch == Arch::Arm => Some(RelType::Lookup),
_ =>
None
}
}
}
fn format_sym_name(sym_name: &[u8]) -> String {
core::str::from_utf8(sym_name)
.map(String::from)
.unwrap_or(String::from("<invalid symbol name>"))
}
pub fn relocate<'a, R: Relocatable>(
arch: Arch, image: &'a Image, dynamic_section: &'a DynamicSection<'a>,
rel: &'a R, resolve: &dyn Fn(&[u8]) -> Option<Elf32_Word>
) -> Result<(), Error> {
// debug!("rel r_offset={:08X} r_info={:08X} r_addend={:08X}", rel.offset(), rel.r_info, rela.r_addend);
let sym;
if rel.sym_info() == 0 {
sym = None;
} else {
sym = Some(dynamic_section.symtab.get(rel.sym_info() as usize)
.ok_or("symbol out of bounds of symbol table")?)
}
let rel_type = RelType::new(arch, rel.type_info())
.ok_or("unsupported relocation type")?;
let value;
match rel_type {
RelType::None =>
return Ok(()),
RelType::Relative => {
let addend = rel.addend(image);
value = image.ptr().wrapping_offset(addend as isize) as Elf32_Word;
}
RelType::Lookup => {
let sym = sym.ok_or("relocation requires an associated symbol")?;
let sym_name = dynamic_section.name_starting_at(sym.st_name as usize)?;
if let Some(addr) = dynamic_section.lookup(sym_name) {
// First, try to resolve against itself.
trace!("looked up symbol {} in image", format_sym_name(sym_name));
value = image.ptr() as u32 + addr;
} else if let Some(addr) = resolve(sym_name) {
// Second, call the user-provided function.
trace!("resolved symbol {:?}", format_sym_name(sym_name));
value = addr;
} else {
// We couldn't find it anywhere.
return Err(Error::Lookup(format_sym_name(sym_name)))
}
}
}
debug!("rel_type={:?} write at {:08X} value {:08X}", rel_type, rel.offset(), value);
image.write(rel.offset(), value)
}