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firmware: rewrite the dynamic linker in Rust.

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This commit is contained in:
whitequark 2017-02-24 18:57:29 +00:00
parent 907589fb58
commit 04ad267055
13 changed files with 3087 additions and 73 deletions
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6
artiq/firmware/Cargo.lock generated
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@ -62,6 +62,10 @@ dependencies = [
"std_artiq 0.0.0",
]
[[package]]
name = "dyld"
version = "0.0.0"
[[package]]
name = "fringe"
version = "1.1.0"
@ -93,6 +97,7 @@ dependencies = [
"build_artiq 0.0.0",
"byteorder 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
"cslice 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
"dyld 0.0.0",
"std_artiq 0.0.0",
]
@ -136,6 +141,7 @@ dependencies = [
"compiler_builtins 0.1.0 (git+https://github.com/rust-lang-nursery/compiler-builtins?rev=631b568)",
"cslice 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
"drtioaux 0.0.0",
"dyld 0.0.0",
"fringe 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
"log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
"logger_artiq 0.0.0",

1
artiq/firmware/ksupport/Cargo.toml
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@ -16,5 +16,6 @@ build_artiq = { path = "../libbuild_artiq" }
alloc_none = { path = "../liballoc_none" }
std_artiq = { path = "../libstd_artiq" }
board = { path = "../libboard" }
dyld = { path = "../libdyld" }
byteorder = { version = "1.0", default-features = false }
cslice = { version = "0.3" }

5
artiq/firmware/ksupport/Makefile
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@ -11,8 +11,7 @@ LDFLAGS += --eh-frame-hdr \
-L../libcompiler-rt \
-L../libbase \
-L../libm \
-L../libunwind \
-L../libdyld
-L../libunwind
RUSTFLAGS += -Cpanic=unwind
@ -24,7 +23,7 @@ $(RUSTOUT)/libksupport.a:
ksupport.elf: $(RUSTOUT)/libksupport.a glue.o
$(LD) $(LDFLAGS) -T $(KSUPPORT_DIRECTORY)/ksupport.ld -o $@ $^ \
-lbase -lm -lcompiler-rt -ldyld -lunwind
-lbase -lm -lcompiler-rt -lunwind
@chmod -x $@
%.o: $(KSUPPORT_DIRECTORY)/%.c

7
artiq/firmware/ksupport/api.rs
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@ -12,12 +12,11 @@ macro_rules! api {
}
}
pub fn resolve(required: &str) -> usize {
pub fn resolve(required: &[u8]) -> Option<u32> {
unsafe {
API.iter()
.find(|&&(exported, _)| exported == required)
.map(|&(_, ptr)| ptr as usize)
.unwrap_or(0)
.find(|&&(exported, _)| exported.as_bytes() == required)
.map(|&(_, ptr)| ptr as u32)
}
}

56
artiq/firmware/ksupport/dyld.rs
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@ -1,56 +0,0 @@
use core::{ptr, slice, str};
use libc::{c_void, c_char, c_int, size_t};
#[allow(non_camel_case_types)]
#[repr(C)]
#[derive(Default)]
struct dyld_info {
__opaque: [usize; 7]
}
extern {
fn dyld_load(shlib: *const c_void, base: usize,
resolve: extern fn(*mut c_void, *const c_char) -> usize,
resolve_data: *mut c_void,
info: *mut dyld_info, error_out: *mut *const c_char) -> c_int;
fn dyld_lookup(symbol: *const c_char, info: *const dyld_info) -> *const c_void;
fn strlen(ptr: *const c_char) -> size_t;
}
pub struct Library {
lower: dyld_info
}
impl Library {
pub unsafe fn load<F>(shlib: &[u8], base: usize, mut resolve: F)
-> Result<Library, &'static str>
where F: Fn(&str) -> usize {
extern fn wrapper<F>(data: *mut c_void, name: *const c_char) -> usize
where F: Fn(&str) -> usize {
unsafe {
let f = data as *mut F;
let name = slice::from_raw_parts(name as *const u8, strlen(name));
(*f)(str::from_utf8_unchecked(name))
}
}
let mut library = Library { lower: dyld_info::default() };
let mut error: *const c_char = ptr::null();
if dyld_load(shlib.as_ptr() as *const _, base,
wrapper::<F>, &mut resolve as *mut _ as *mut _,
&mut library.lower, &mut error) == 0 {
let error = slice::from_raw_parts(error as *const u8, strlen(error));
Err(str::from_utf8_unchecked(error))
} else {
Ok(library)
}
}
pub unsafe fn lookup(&self, symbol: &str) -> usize {
assert!(symbol.len() < 32);
let mut buf = [0u8; 32];
buf[0..symbol.as_bytes().len()].copy_from_slice(symbol.as_bytes());
dyld_lookup(&buf as *const _ as *const c_char, &self.lower) as usize
}
}

20
artiq/firmware/ksupport/lib.rs
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@ -9,6 +9,7 @@ extern crate libc;
extern crate byteorder;
extern crate board;
extern crate cslice;
extern crate dyld;
#[path = "../runtime/mailbox.rs"]
mod mailbox;
@ -20,10 +21,9 @@ mod kernel_proto;
#[path = "../runtime/rpc_proto.rs"]
mod rpc_proto;
mod dyld;
mod api;
use core::{mem, ptr, str};
use core::{mem, ptr, slice, str};
use std::io::Cursor;
use cslice::{CSlice, AsCSlice};
use kernel_proto::*;
@ -294,8 +294,12 @@ unsafe fn attribute_writeback(typeinfo: *const ()) {
#[no_mangle]
pub unsafe fn main() {
let image = slice::from_raw_parts_mut(kernel_proto::KERNELCPU_PAYLOAD_ADDRESS as *mut u8,
kernel_proto::KERNELCPU_LAST_ADDRESS -
kernel_proto::KERNELCPU_PAYLOAD_ADDRESS);
let library = recv!(&LoadRequest(library) => {
match Library::load(library, kernel_proto::KERNELCPU_PAYLOAD_ADDRESS, api::resolve) {
match Library::load(library, image, &api::resolve) {
Err(error) => {
send(&LoadReply(Err(error)));
loop {}
@ -307,16 +311,16 @@ pub unsafe fn main() {
}
});
let __bss_start = library.lookup("__bss_start");
let _end = library.lookup("_end");
ptr::write_bytes(__bss_start as *mut u8, 0, _end - __bss_start);
let __bss_start = library.lookup(b"__bss_start").unwrap();
let _end = library.lookup(b"_end").unwrap();
ptr::write_bytes(__bss_start as *mut u8, 0, (_end - __bss_start) as usize);
send(&NowInitRequest);
recv!(&NowInitReply(now) => NOW = now);
(mem::transmute::<usize, fn()>(library.lookup("__modinit__")))();
(mem::transmute::<u32, fn()>(library.lookup(b"__modinit__").unwrap()))();
send(&NowSave(NOW));
attribute_writeback(library.lookup("typeinfo") as *const ());
attribute_writeback(library.lookup(b"typeinfo").unwrap_or(0) as *const ());
send(&RunFinished);

8
artiq/firmware/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
artiq/firmware/libdyld/elf.rs Normal file
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File diff suppressed because it is too large Load Diff

313
artiq/firmware/libdyld/lib.rs Normal file
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@ -0,0 +1,313 @@
#![no_std]
#![feature(untagged_unions, ptr_unaligned)]
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],
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 fixup_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_off = sym.st_name as usize;
let sym_name_end =
self.strtab.iter().skip(sym_name_off).position(|&x| x == 0)
.ok_or("symbol in symbol table not null-terminated")?;
let sym_name =
self.strtab.get(sym_name_off..sym_name_off + sym_name_end)
.ok_or("cannot read symbol name")?;
// 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")?
}
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;
unsafe { *ptr = value }
Ok(())
}
pub fn load(data: &[u8], image: &'a mut [u8], resolve: &Fn(&[u8]) -> Option<Elf32_Word>)
-> Result<Library<'a>, Error<'a>> {
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 != 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,
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.fixup_rela(r, resolve)? }
for r in pltrel { library.fixup_rela(r, resolve)? }
Ok(library)
}
}

1
artiq/firmware/runtime/Cargo.toml
View File

@ -19,6 +19,7 @@ logger_artiq = { path = "../liblogger_artiq" }
cslice = { version = "0.3" }
log = { version = "0.3", default-features = false, features = ["max_level_debug"] }
board = { path = "../libboard", features = ["uart_console"] }
dyld = { path = "../libdyld" }
drtioaux = { path = "../libdrtioaux" }
fringe = { version = "= 1.1.0", default-features = false, features = ["alloc"] }
byteorder = { version = "1.0", default-features = false }

3
artiq/firmware/runtime/kernel_proto.rs
View File

@ -1,6 +1,7 @@
#![allow(dead_code)]
use core::fmt;
use dyld;
pub const KERNELCPU_EXEC_ADDRESS: usize = 0x40800000;
pub const KERNELCPU_PAYLOAD_ADDRESS: usize = 0x40840000;
@ -22,7 +23,7 @@ pub struct Exception<'a> {
#[derive(Debug)]
pub enum Message<'a> {
LoadRequest(&'a [u8]),
LoadReply(Result<(), &'a str>),
LoadReply(Result<(), dyld::Error<'a>>),
NowInitRequest,
NowInitReply(u64),

1
artiq/firmware/runtime/lib.rs
View File

@ -16,6 +16,7 @@ extern crate smoltcp;
extern crate board;
#[cfg(has_drtio)]
extern crate drtioaux;
extern crate dyld;
use std::boxed::Box;
use smoltcp::wire::{EthernetAddress, IpAddress};

2
artiq/firmware/runtime/session.rs
View File

@ -179,7 +179,7 @@ unsafe fn kern_load(io: &Io, session: &mut Session, library: &[u8]) -> io::Resul
session.kernel_state = KernelState::Loaded;
Ok(())
}
&kern::LoadReply(Err(error)) => {
&kern::LoadReply(Err(ref error)) => {
kernel::stop();
Err(io::Error::new(io::ErrorKind::Other,
format!("cannot load kernel: {}", error)))