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feat: ✨ Add UnsafeCell trick 

It replaces old "C" style linker symbol references.
This commit is contained in:
Berkus Decker 2022-04-24 22:04:27 +03:00
parent 29d61f4bdb
commit 113b4abbc5
2 changed files with 17 additions and 18 deletions
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26
bin/chainboot/src/boot.rs
View File

@ -9,6 +9,7 @@ core::arch::global_asm!(include_str!("boot.s"));
#[cfg(not(feature = "asm"))]
pub unsafe extern "C" fn _start() -> ! {
use {
core::cell::UnsafeCell,
cortex_a::registers::{MPIDR_EL1, SP},
machine::endless_sleep,
tock_registers::interfaces::{Readable, Writeable},
@ -24,31 +25,30 @@ pub unsafe extern "C" fn _start() -> ! {
// These are a problem, because they are not interpreted as constants here.
// Subsequently, this code tries to read values from not-yet-existing data locations.
extern "C" {
extern "Rust" {
// Boundaries of the .bss section, provided by the linker script
static mut __bss_start: u64;
static mut __bss_end_exclusive: u64;
static __bss_start: UnsafeCell<()>;
static __bss_end_exclusive: UnsafeCell<()>;
// Load address of the kernel binary
static mut __binary_nonzero_lma: u64;
static __binary_nonzero_lma: UnsafeCell<()>;
// Address to relocate to and image size
static mut __binary_nonzero_vma: u64;
static mut __binary_nonzero_vma_end_exclusive: u64;
static __binary_nonzero_vma: UnsafeCell<()>;
static __binary_nonzero_vma_end_exclusive: UnsafeCell<()>;
// Stack top
static mut __boot_core_stack_end_exclusive: u64;
static __boot_core_stack_end_exclusive: UnsafeCell<()>;
}
// Set stack pointer.
SP.set(&mut __boot_core_stack_end_exclusive as *mut u64 as u64);
SP.set(__boot_core_stack_end_exclusive.get() as u64);
// Zeroes the .bss section
r0::zero_bss(&mut __bss_start, &mut __bss_end_exclusive);
r0::zero_bss(__bss_start.get() as u64, __bss_end_exclusive.get() as u64);
// Relocate the code
core::ptr::copy_nonoverlapping(
&mut __binary_nonzero_lma as *const u64,
&mut __binary_nonzero_vma as *mut u64,
(&mut __binary_nonzero_vma_end_exclusive as *mut u64 as u64
- &mut __binary_nonzero_vma as *mut u64 as u64) as usize,
__binary_nonzero_lma.get() as *const u64,
__binary_nonzero_vma.get() as *mut u64,
(__binary_nonzero_vma_end_exclusive.get() as usize - __binary_nonzero_vma.get() as usize),
);
_start_rust();

9
nucleus/src/main.rs
View File

@ -23,6 +23,7 @@ use core::panic::PanicInfo;
use machine::devices::SerialOps;
use {
cfg_if::cfg_if,
core::cell::UnsafeCell,
machine::{
arch, entry, memory,
platform::rpi3::{
@ -55,14 +56,12 @@ fn init_mmu() {
}
fn init_exception_traps() {
extern "C" {
static __exception_vectors_start: u64;
extern "Rust" {
static __exception_vectors_start: UnsafeCell<()>;
}
unsafe {
let exception_vectors_start: u64 = &__exception_vectors_start as *const _ as u64;
arch::traps::set_vbar_el1_checked(exception_vectors_start)
arch::traps::set_vbar_el1_checked(__exception_vectors_start.get() as u64)
.expect("Vector table properly aligned!");
}
println!("[!] Exception traps set up");