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ld_so: better support for other arches

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This commit is contained in:
Jeremy Soller
2025-04-18 14:26:39 -06:00
parent 310b097da6
commit 03f863d742
1 changed files with 117 additions and 33 deletions
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src/ld_so/dso.rs
+117 -33
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@@ -3,7 +3,7 @@
//! * <https://www.akkadia.org/drepper/dsohowto.pdf>
use object::{
elf::{self, Sym64},
elf,
read::elf::{
Dyn as _, GnuHashTable, HashTable as SysVHashTable, ProgramHeader as _, Rel as _,
Rela as _, Sym as _, Version, VersionTable,
@@ -207,6 +207,89 @@ impl From<&Rel> for Relocation {
}
}
#[allow(dead_code)]
#[derive(Clone, Copy, Debug)]
pub enum R {
COPY,
DIRECT,
DTPMOD,
DTPOFF,
GLOB_DAT,
IRELATIVE,
JUMP_SLOT,
RELATIVE,
PC,
TPOFF,
UNKNOWN(u32),
}
impl R {
#[cfg(target_arch = "aarch64")]
pub fn new(kind: u32) -> Self {
//WARNING: Only use R_AARCH64_* constants here!
match kind {
elf::R_AARCH64_COPY => R::COPY,
elf::R_AARCH64_ABS64 => R::DIRECT,
elf::R_AARCH64_GLOB_DAT => R::GLOB_DAT,
elf::R_AARCH64_IRELATIVE => R::IRELATIVE,
elf::R_AARCH64_JUMP_SLOT => R::JUMP_SLOT,
elf::R_AARCH64_RELATIVE => R::RELATIVE,
_ => R::UNKNOWN(kind),
}
}
#[cfg(target_arch = "riscv64")]
pub fn new(kind: u32) -> Self {
//WARNING: Only use R_RISCV_* constants here!
match kind {
elf::R_RISCV_COPY => R::COPY,
elf::R_RISCV_64 => R::DIRECT,
elf::R_RISCV_TLS_DTPMOD64 => R::DTPMOD,
elf::R_RISCV_TLS_DTPREL64 => R::DTPOFF,
elf::R_RISCV_IRELATIVE => R::IRELATIVE,
elf::R_RISCV_JUMP_SLOT => R::JUMP_SLOT,
elf::R_RISCV_RELATIVE => R::RELATIVE,
elf::R_RISCV_TLS_TPREL64 => R::TPOFF,
_ => R::UNKNOWN(kind),
}
}
#[cfg(target_arch = "x86")]
pub fn new(kind: u32) -> Self {
//WARNING: Only use R_386_* constants here!
match kind {
elf::R_386_COPY => R::COPY,
elf::R_386_32 => R::DIRECT,
elf::R_386_TLS_DTPMOD32 => R::DTPMOD,
elf::R_386_TLS_DTPOFF32 => R::DTPOFF,
elf::R_386_GLOB_DAT => R::GLOB_DAT,
elf::R_386_IRELATIVE => R::IRELATIVE,
elf::R_386_JMP_SLOT => R::JUMP_SLOT,
elf::R_386_PC32 => R::PC,
elf::R_386_RELATIVE => R::RELATIVE,
elf::R_386_TLS_TPOFF32 => R::TPOFF,
_ => R::UNKNOWN(kind),
}
}
#[cfg(target_arch = "x86_64")]
pub fn new(kind: u32) -> Self {
//WARNING: Only use R_X86_64_* constants here!
match kind {
elf::R_X86_64_COPY => R::COPY,
elf::R_X86_64_64 => R::DIRECT,
elf::R_X86_64_DTPMOD64 => R::DTPMOD,
elf::R_X86_64_DTPOFF64 => R::DTPOFF,
elf::R_X86_64_GLOB_DAT => R::GLOB_DAT,
elf::R_X86_64_IRELATIVE => R::IRELATIVE,
elf::R_X86_64_JUMP_SLOT => R::JUMP_SLOT,
elf::R_X86_64_RELATIVE => R::RELATIVE,
elf::R_X86_64_TPOFF64 => R::TPOFF,
_ => R::UNKNOWN(kind),
}
}
}
#[derive(Debug, PartialEq)]
#[repr(u8)]
pub enum SymbolBinding {
@@ -726,11 +809,12 @@ impl DSO {
fn static_relocate(&self, global_scope: &Scope, reloc: Relocation) -> object::Result<()> {
let b = self.mmap.as_ptr() as usize;
let r = R::new(reloc.kind);
let (sym, my_sym) = if reloc.sym.0 > 0 {
let name = self.dynamic.symbol_name(reloc.sym).unwrap();
let lookup_scopes = [global_scope, self.scope()];
let sym = if reloc.kind == elf::R_X86_64_COPY {
let sym = if matches!(r, R::COPY) {
lookup_scopes
.iter()
.find_map(|scope| scope._get_sym(name, 1))
@@ -755,45 +839,44 @@ impl DSO {
} else {
reloc.offset as *mut u8
};
let p = ptr as usize;
let set_u64 = |value| unsafe {
*(ptr as *mut u64) = value;
//TODO: support different sizes?
let set_usize = |value| unsafe {
*(ptr as *mut usize) = value;
};
match reloc.kind {
elf::R_X86_64_64 => set_u64((s + a) as u64),
elf::R_X86_64_DTPMOD64 => set_u64(self.tls_module_id as u64),
elf::R_X86_64_DTPOFF64 => {
match r {
R::DIRECT => set_usize(s + a),
R::DTPMOD => set_usize(self.tls_module_id),
R::DTPOFF => {
if s != 0 {
set_u64((s - b) as u64);
set_usize(s - b);
} else {
set_u64(s as u64);
set_usize(s);
}
}
elf::R_X86_64_GLOB_DAT => set_u64(s as u64),
elf::R_X86_64_RELATIVE => set_u64((b + a) as u64),
elf::R_X86_64_TPOFF64 => {
R::GLOB_DAT => set_usize(s),
R::PC => set_usize((s + a).wrapping_sub(p)),
R::RELATIVE => set_usize(b + a),
R::TPOFF => {
if reloc.sym.0 > 0 {
let (sym, _) = sym
.as_ref()
.expect("R_X86_64_TPOFF64 called without valid symbol");
set_u64((sym.value + a).wrapping_sub(t) as u64);
let (sym, _) = sym.as_ref().expect("R::TPOFF called without valid symbol");
set_usize((sym.value + a).wrapping_sub(t));
} else {
set_u64(a.wrapping_sub(t) as u64);
set_usize(a.wrapping_sub(t));
}
}
elf::R_X86_64_IRELATIVE => unsafe {
let f: unsafe extern "C" fn() -> u64 = core::mem::transmute(b + a);
set_u64(f());
R::IRELATIVE => unsafe {
let f: unsafe extern "C" fn() -> usize = core::mem::transmute(b + a);
set_usize(f());
},
elf::R_X86_64_COPY => unsafe {
let (sym, obj) = sym
.as_ref()
.expect("R_X86_64_COPY called without valid symbol");
let my_sym = my_sym.expect("R_X86_64_COPY called without valid symbol");
R::COPY => unsafe {
let (sym, obj) = sym.as_ref().expect("R::COPY called without valid symbol");
let my_sym = my_sym.expect("R::COPY called without valid symbol");
assert!(
sym.size == my_sym.st_size(NativeEndian) as usize,
"R_X86_64_COPY failed: I was trying to use the symbol {} from {} for {} but they had different sizes. Please consider relinking.",
"R::COPY failed: I was trying to use the symbol {} from {} for {} but they had different sizes. Please consider relinking.",
sym.name,
obj.name,
self.name
@@ -801,7 +884,7 @@ impl DSO {
// SAFETY: Both the source and destination have the same size.
ptr::copy_nonoverlapping(sym.as_ptr() as *const u8, ptr, sym.size);
},
_ => unimplemented!("relocation type {:#x}", reloc.kind),
_ => unimplemented!("relocation type {:?}", r),
}
Ok(())
@@ -841,16 +924,17 @@ impl DSO {
reloc.offset as *mut usize
};
match (reloc.kind, resolve) {
(elf::R_X86_64_JUMP_SLOT, Resolve::Lazy) if self.pie => unsafe {
let r = R::new(reloc.kind);
match (r, resolve) {
(R::JUMP_SLOT, Resolve::Lazy) if self.pie => unsafe {
*ptr += object_base_addr;
},
(elf::R_X86_64_JUMP_SLOT, Resolve::Lazy) => {
(R::JUMP_SLOT, Resolve::Lazy) => {
// NOP.
}
(elf::R_X86_64_JUMP_SLOT, Resolve::Now) => {
(R::JUMP_SLOT, Resolve::Now) => {
let name = self.dynamic.symbol_name(reloc.sym).unwrap();
let resolved = resolve_sym(name, &[global_scope, self.scope()])
@@ -863,7 +947,7 @@ impl DSO {
}
_ => {
unimplemented!("relocation type {:#x}", reloc.kind)
unimplemented!("relocation type {:?} with resolve {:?}", r, resolve)
}
}
}