69 lines
2.4 KiB
Rust
69 lines
2.4 KiB
Rust
// Assembly counterpart to this file.
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#[cfg(feature = "asm")]
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core::arch::global_asm!(include_str!("boot.s"));
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// This is quite impossible - the linker constants are resolved to fully constant offsets in asm
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// version, but are image-relative symbols in rust, and I see no way to force it otherwise.
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#[no_mangle]
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#[link_section = ".text._start"]
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#[cfg(not(feature = "asm"))]
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pub unsafe extern "C" fn _start() -> ! {
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use {
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cortex_a::registers::{MPIDR_EL1, SP},
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machine::endless_sleep,
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tock_registers::interfaces::{Readable, Writeable},
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};
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const CORE_0: u64 = 0;
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const CORE_MASK: u64 = 0x3;
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if CORE_0 == MPIDR_EL1.get() & CORE_MASK {
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// if not core0, infinitely wait for events
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endless_sleep()
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}
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// These are a problem, because they are not interpreted as constants here.
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// Subsequently, this code tries to read values from not-yet-existing data locations.
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extern "C" {
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// Boundaries of the .bss section, provided by the linker script
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static mut __bss_start: u64;
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static mut __bss_end_exclusive: u64;
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// Load address of the kernel binary
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static mut __binary_nonzero_lma: u64;
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// Address to relocate to and image size
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static mut __binary_nonzero_vma: u64;
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static mut __binary_nonzero_vma_end_exclusive: u64;
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// Stack top
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static mut __boot_core_stack_end_exclusive: u64;
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}
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// Set stack pointer.
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SP.set(&mut __boot_core_stack_end_exclusive as *mut u64 as u64);
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// Zeroes the .bss section
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r0::zero_bss(&mut __bss_start, &mut __bss_end_exclusive);
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// Relocate the code
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core::ptr::copy_nonoverlapping(
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&mut __binary_nonzero_lma as *const u64,
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&mut __binary_nonzero_vma as *mut u64,
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(&mut __binary_nonzero_vma_end_exclusive as *mut u64 as u64
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- &mut __binary_nonzero_vma as *mut u64 as u64) as usize,
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);
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_start_rust();
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}
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//--------------------------------------------------------------------------------------------------
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// Public Code
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//--------------------------------------------------------------------------------------------------
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/// The Rust entry of the `kernel` binary.
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///
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/// The function is called from the assembly `_start` function, keep it to support "asm" feature.
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#[no_mangle]
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#[inline(always)]
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pub unsafe fn _start_rust(max_kernel_size: u64) -> ! {
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crate::kernel_init(max_kernel_size)
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}
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