yggdrasil/userspace/dyn-loader/src/relocation/i686.rs

use elf::relocation::{Rel, Rela};

use crate::{error::Error, object::ResolvedSymbol, state::State};

use super::{RelValue, RelaValue, Relocation};

impl Relocation for Rela {
    type Value = RelaValue;

    fn resolve(
        &self,
        _state: &State,
        _name: &str,
        _symbol: &ResolvedSymbol,
        _load_base: usize,
    ) -> Result<Option<Self::Value>, Error> {
        unimplemented!("rela-type relocations are not implemented for i686")
    }
}

impl Relocation for Rel {
    type Value = RelValue;

    fn resolve(
        &self,
        state: &State,
        name: &str,
        symbol: &ResolvedSymbol,
        load_base: usize,
    ) -> Result<Option<Self::Value>, Error> {
        match symbol {
            ResolvedSymbol::Tls(tls) => match self.r_type {
                // R_386_DTPMOD32: TLS module ID
                35 => Ok(Some(RelValue::DWordNoAddend(tls.module_id as _))),
                // R_386_DTPOFF32: TLS offset within a module
                36 => Ok(Some(RelValue::DWordNoAddend(tls.offset as _))),
                // R_386_TPOFF: tp-relative offset
                14 => {
                    // Need to extract fixed global offset
                    let tls_layout = state.tls_layout.as_ref().unwrap();
                    // Offset from TLS start
                    let offset = tls_layout.offset(tls.module_id, tls.offset).unwrap();
                    let offset_from_tp = -((tls_layout.tp_offset - offset) as i32);
                    log::debug!("{}@tpoff -> {}", name, offset_from_tp);

                    Ok(Some(RelValue::DWordNoAddend(offset_from_tp)))
                }
                // 14 => Ok(Some(RelValue::DWordNoAddend()))

                _ => todo!("Unsupported relocation against TLS symbol: {}", self.r_type)
            },
            &ResolvedSymbol::Null(object_id) => match self.r_type {
                // R_386_RELATIVE: B + A
                8 => Ok(Some(RelValue::DWord(load_base as _))),

                // R_386_DTPMOD32: TLS module ID
                35 => Ok(Some(RelValue::DWordNoAddend(object_id as _))),

                _ => todo!("Unsupported relocation against NULL symbol: {}", self.r_type),
            }
            _ => {
                let s: i32 = symbol.value().try_into().unwrap();
                if s == 0  {
                    todo!("Relocation: r_type={}, name={name} is NULL", self.r_type)
                }
                match self.r_type {
                    // R_386_32: S + A
                    1 => Ok(Some(RelValue::DWord(s))),
                    // R_386_GLOB_DAT: S
                    // R_386_JMP_SLOT: S
                    6 | 7 => Ok(Some(RelValue::DWordNoAddend(s))),

                    _ => todo!("Unsupported relocation type: {}", self.r_type)
                }
            }
        }
    }
}