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add libdyld from ARTIQ e8b73876ab60e202bec0a2e5119bd7b740d0c78d

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This commit is contained in:
Sebastien Bourdeauducq 2020-04-12 18:40:15 +08:00
parent a56221fcfb
commit 064e114a0b
5 changed files with 3092 additions and 5 deletions
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5
Cargo.lock generated
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@ -30,6 +30,10 @@ version = "0.1.26"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "036b035e9ebcd705affece16319223d19f229e2358be6e3b7b094e57193312e6"
[[package]]
name = "dyld"
version = "0.0.0"
[[package]]
name = "libasync"
version = "0.0.0"
@ -150,6 +154,7 @@ checksum = "bd7a31eed1591dcbc95d92ad7161908e72f4677f8fabf2a32ca49b4237cbf211"
name = "runtime"
version = "0.1.0"
dependencies = [
"dyld",
"libasync",
"libboard_zynq",
"libsupport_zynq",

8
libdyld/Cargo.toml Normal file
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@ -0,0 +1,8 @@
[package]
authors = ["M-Labs"]
name = "dyld"
version = "0.0.0"
[lib]
name = "dyld"
path = "lib.rs"

2737
libdyld/elf.rs Normal file
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File diff suppressed because it is too large Load Diff

339
libdyld/lib.rs Normal file
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@ -0,0 +1,339 @@
#![no_std]
use core::{mem, ptr, fmt, slice, str, convert};
use elf::*;
pub mod elf;
fn read_unaligned<T: Copy>(data: &[u8], offset: usize) -> Result<T, ()> {
if data.len() < offset + mem::size_of::<T>() {
Err(())
} else {
let ptr = data.as_ptr().wrapping_offset(offset as isize) as *const T;
Ok(unsafe { ptr::read_unaligned(ptr) })
}
}
fn get_ref<T: Copy>(data: &[u8], offset: usize) -> Result<&T, ()> {
if data.len() < offset + mem::size_of::<T>() {
Err(())
} else if (data.as_ptr() as usize + offset) & (mem::align_of::<T>() - 1) != 0 {
Err(())
} else {
let ptr = data.as_ptr().wrapping_offset(offset as isize) as *const T;
Ok(unsafe { &*ptr })
}
}
fn get_ref_slice<T: Copy>(data: &[u8], offset: usize, len: usize) -> Result<&[T], ()> {
if data.len() < offset + mem::size_of::<T>() * len {
Err(())
} else if (data.as_ptr() as usize + offset) & (mem::align_of::<T>() - 1) != 0 {
Err(())
} else {
let ptr = data.as_ptr().wrapping_offset(offset as isize) as *const T;
Ok(unsafe { slice::from_raw_parts(ptr, len) })
}
}
fn elf_hash(name: &[u8]) -> u32 {
let mut h: u32 = 0;
for c in name {
h = (h << 4) + *c as u32;
let g = h & 0xf0000000;
if g != 0 {
h ^= g >> 24;
h &= !g;
}
}
h
}
#[derive(Debug)]
pub enum Error<'a> {
Parsing(&'static str),
Lookup(&'a [u8])
}
impl<'a> convert::From<&'static str> for Error<'a> {
fn from(desc: &'static str) -> Error<'a> {
Error::Parsing(desc)
}
}
impl<'a> fmt::Display for Error<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
&Error::Parsing(desc) =>
write!(f, "parse error: {}", desc),
&Error::Lookup(sym) =>
match str::from_utf8(sym) {
Ok(sym) => write!(f, "symbol lookup error: {}", sym),
Err(_) => write!(f, "symbol lookup error: {:?}", sym)
}
}
}
}
pub struct Library<'a> {
image_off: Elf32_Addr,
image_sz: usize,
strtab: &'a [u8],
symtab: &'a [Elf32_Sym],
pltrel: &'a [Elf32_Rela],
hash_bucket: &'a [Elf32_Word],
hash_chain: &'a [Elf32_Word],
}
impl<'a> Library<'a> {
pub fn lookup(&self, name: &[u8]) -> Option<Elf32_Word> {
let hash = elf_hash(name);
let mut index = self.hash_bucket[hash as usize % self.hash_bucket.len()] as usize;
loop {
if index == STN_UNDEF { return None }
let sym = &self.symtab[index];
let sym_name_off = sym.st_name as usize;
match self.strtab.get(sym_name_off..sym_name_off + name.len()) {
Some(sym_name) if sym_name == name => {
if ELF32_ST_BIND(sym.st_info) & STB_GLOBAL == 0 {
return None
}
match sym.st_shndx {
SHN_UNDEF => return None,
SHN_ABS => return Some(sym.st_value),
_ => return Some(self.image_off + sym.st_value)
}
}
_ => (),
}
index = self.hash_chain[index] as usize;
}
}
fn name_starting_at(&self, offset: usize) -> Result<&'a [u8], Error<'a>> {
let size = self.strtab.iter().skip(offset).position(|&x| x == 0)
.ok_or("symbol in symbol table not null-terminated")?;
Ok(self.strtab.get(offset..offset + size)
.ok_or("cannot read symbol name")?)
}
fn update_rela(&self, rela: &Elf32_Rela, value: Elf32_Word) -> Result<(), Error<'a>> {
if rela.r_offset as usize + mem::size_of::<Elf32_Addr>() > self.image_sz {
return Err("relocation out of image bounds")?
}
let ptr = (self.image_off + rela.r_offset) as *mut Elf32_Addr;
Ok(unsafe { *ptr = value })
}
// This is unsafe because it mutates global data (the PLT).
pub unsafe fn rebind(&self, name: &[u8], addr: Elf32_Word) -> Result<(), Error<'a>> {
for rela in self.pltrel.iter() {
match ELF32_R_TYPE(rela.r_info) {
R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT => {
let sym = self.symtab.get(ELF32_R_SYM(rela.r_info) as usize)
.ok_or("symbol out of bounds of symbol table")?;
let sym_name = self.name_starting_at(sym.st_name as usize)?;
if sym_name == name {
self.update_rela(rela, addr)?
}
}
// No associated symbols for other relocation types.
_ => ()
}
}
Ok(())
}
fn resolve_rela(&self, rela: &Elf32_Rela, resolve: &Fn(&[u8]) -> Option<Elf32_Word>)
-> Result<(), Error<'a>> {
let sym;
if ELF32_R_SYM(rela.r_info) == 0 {
sym = None;
} else {
sym = Some(self.symtab.get(ELF32_R_SYM(rela.r_info) as usize)
.ok_or("symbol out of bounds of symbol table")?)
}
let value;
match ELF32_R_TYPE(rela.r_info) {
R_OR1K_NONE =>
return Ok(()),
R_OR1K_RELATIVE =>
value = self.image_off + rela.r_addend as Elf32_Word,
R_OR1K_32 | R_OR1K_GLOB_DAT | R_OR1K_JMP_SLOT => {
let sym = sym.ok_or("relocation requires an associated symbol")?;
let sym_name = self.name_starting_at(sym.st_name as usize)?;
// First, try to resolve against itself.
match self.lookup(sym_name) {
Some(addr) => value = addr,
None => {
// Second, call the user-provided function.
match resolve(sym_name) {
Some(addr) => value = addr,
None => {
// We couldn't find it anywhere.
return Err(Error::Lookup(sym_name))
}
}
}
}
}
_ => return Err("unsupported relocation type")?
}
self.update_rela(rela, value)
}
pub fn load(data: &[u8], image: &'a mut [u8], resolve: &Fn(&[u8]) -> Option<Elf32_Word>)
-> Result<Library<'a>, Error<'a>> {
#![allow(unused_assignments)]
let ehdr = read_unaligned::<Elf32_Ehdr>(data, 0)
.map_err(|()| "cannot read ELF header")?;
const IDENT: [u8; EI_NIDENT] = [
ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
ELFCLASS32, ELFDATA2MSB, EV_CURRENT, ELFOSABI_NONE,
/* ABI version */ 0, /* padding */ 0, 0, 0, 0, 0, 0, 0
];
#[cfg(target_arch = "or1k")]
const ARCH: u16 = EM_OPENRISC;
#[cfg(not(target_arch = "or1k"))]
const ARCH: u16 = EM_NONE;
if ehdr.e_ident != IDENT || ehdr.e_type != ET_DYN || ehdr.e_machine != ARCH {
return Err("not a shared library for current architecture")?
}
let mut dyn_off = None;
for i in 0..ehdr.e_phnum {
let phdr_off = ehdr.e_phoff as usize + mem::size_of::<Elf32_Phdr>() * i as usize;
let phdr = read_unaligned::<Elf32_Phdr>(data, phdr_off)
.map_err(|()| "cannot read program header")?;
match phdr.p_type {
PT_LOAD => {
if (phdr.p_vaddr + phdr.p_filesz) as usize > image.len() ||
(phdr.p_offset + phdr.p_filesz) as usize > data.len() {
return Err("program header requests an out of bounds load")?
}
let dst = image.get_mut(phdr.p_vaddr as usize..
(phdr.p_vaddr + phdr.p_filesz) as usize)
.ok_or("cannot write to program header destination")?;
let src = data.get(phdr.p_offset as usize..
(phdr.p_offset + phdr.p_filesz) as usize)
.ok_or("cannot read from program header source")?;
dst.copy_from_slice(src);
}
PT_DYNAMIC =>
dyn_off = Some(phdr.p_vaddr),
_ => ()
}
}
let (mut strtab_off, mut strtab_sz) = (0, 0);
let (mut symtab_off, mut symtab_sz) = (0, 0);
let (mut rela_off, mut rela_sz) = (0, 0);
let (mut pltrel_off, mut pltrel_sz) = (0, 0);
let (mut hash_off, mut hash_sz) = (0, 0);
let mut sym_ent = 0;
let mut rela_ent = 0;
let mut nbucket = 0;
let mut nchain = 0;
let dyn_off = dyn_off.ok_or("cannot find a dynamic header")?;
for i in 0.. {
let dyn_off = dyn_off as usize + i * mem::size_of::<Elf32_Dyn>();
let dyn = get_ref::<Elf32_Dyn>(image, dyn_off)
.map_err(|()| "cannot read dynamic header")?;
let val = unsafe { dyn.d_un.d_val } as usize;
match dyn.d_tag {
DT_NULL => break,
DT_REL => return Err("relocations with implicit addend are not supported")?,
DT_STRTAB => strtab_off = val,
DT_STRSZ => strtab_sz = val,
DT_SYMTAB => symtab_off = val,
DT_SYMENT => sym_ent = val,
DT_RELA => rela_off = val,
DT_RELASZ => rela_sz = val / mem::size_of::<Elf32_Rela>(),
DT_RELAENT => rela_ent = val,
DT_JMPREL => pltrel_off = val,
DT_PLTRELSZ => pltrel_sz = val / mem::size_of::<Elf32_Rela>(),
DT_HASH => {
nbucket = *get_ref::<Elf32_Word>(image, val + 0)
.map_err(|()| "cannot read hash bucket count")? as usize;
nchain = *get_ref::<Elf32_Word>(image, val + 4)
.map_err(|()| "cannot read hash chain count")? as usize;
hash_off = val + 8;
hash_sz = nbucket + nchain;
}
_ => ()
}
}
if sym_ent != mem::size_of::<Elf32_Sym>() {
return Err("incorrect symbol entry size")?
}
if rela_ent != 0 && rela_ent != mem::size_of::<Elf32_Rela>() {
return Err("incorrect relocation entry size")?
}
// These are the same--there are as many chains as buckets, and the chains only contain
// the symbols that overflowed the bucket.
symtab_sz = nchain;
// Drop the mutability. See also the comment below.
let image = &*image;
let strtab = get_ref_slice::<u8>(image, strtab_off, strtab_sz)
.map_err(|()| "cannot read string table")?;
let symtab = get_ref_slice::<Elf32_Sym>(image, symtab_off, symtab_sz)
.map_err(|()| "cannot read symbol table")?;
let rela = get_ref_slice::<Elf32_Rela>(image, rela_off, rela_sz)
.map_err(|()| "cannot read rela entries")?;
let pltrel = get_ref_slice::<Elf32_Rela>(image, pltrel_off, pltrel_sz)
.map_err(|()| "cannot read pltrel entries")?;
let hash = get_ref_slice::<Elf32_Word>(image, hash_off, hash_sz)
.map_err(|()| "cannot read hash entries")?;
let library = Library {
image_off: image.as_ptr() as Elf32_Word,
image_sz: image.len(),
strtab: strtab,
symtab: symtab,
pltrel: pltrel,
hash_bucket: &hash[..nbucket],
hash_chain: &hash[nbucket..nbucket + nchain],
};
// If a borrow exists anywhere, the borrowed memory cannot be mutated except
// through that pointer or it's UB. However, we need to retain pointers
// to the symbol tables and relocations, and at the same time mutate the code
// to resolve the relocations.
//
// To avoid invoking UB, we drop the only pointer to the entire area (which is
// unique since it's a &mut); we retain pointers to the various tables, but
// we never write to the memory they refer to, so it's safe.
mem::drop(image);
for r in rela { library.resolve_rela(r, resolve)? }
for r in pltrel { library.resolve_rela(r, resolve)? }
Ok(library)
}
}

8
runtime/Cargo.toml
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@ -10,11 +10,9 @@ target_zc706 = ["libboard_zynq/target_zc706", "libsupport_zynq/target_zc706"]
default = ["target_zc706"]
[dependencies]
num-traits = { version = "0.2", default-features = false }
num-derive = "0.3"
libboard_zynq = { git = "https://git.m-labs.hk/M-Labs/zc706.git" }
libsupport_zynq = { git = "https://git.m-labs.hk/M-Labs/zc706.git" }
libasync = { git = "https://git.m-labs.hk/M-Labs/zc706.git" }
num-derive = "0.3"
[dependencies.num-traits]
version = "0.2"
default-features = false
dyld = { path = "../libdyld" }