56 lines
1.4 KiB
Rust
56 lines
1.4 KiB
Rust
use {
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spin::Lazy,
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x86_64::{
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structures::{
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gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector},
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tss::TaskStateSegment,
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},
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VirtAddr,
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},
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};
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pub const DOUBLE_FAULT_IX: u16 = 0;
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pub unsafe fn init() {
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use x86_64::instructions::{
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segmentation::{Segment, CS, SS},
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tables::load_tss,
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};
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log::info!("Initialising GDT");
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GDT.0.load();
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CS::set_reg(GDT.1.kcode);
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SS::set_reg(GDT.1.kdata);
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load_tss(GDT.1.tss);
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}
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struct Selectors {
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kcode: SegmentSelector,
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kdata: SegmentSelector,
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tss: SegmentSelector,
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}
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static TSS: Lazy<TaskStateSegment> = Lazy::new(|| {
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let mut tss = TaskStateSegment::new();
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tss.interrupt_stack_table[usize::from(DOUBLE_FAULT_IX)] = {
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const SIZE: usize = 5 * 1024;
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let stack = unsafe {
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alloc::alloc::alloc_zeroed(
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alloc::alloc::Layout::from_size_align(SIZE, 1).expect("stack pointer"),
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)
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};
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VirtAddr::from_ptr(stack) + SIZE
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};
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tss
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});
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static GDT: Lazy<(GlobalDescriptorTable, Selectors)> = Lazy::new(|| {
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let mut gdt = GlobalDescriptorTable::new();
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let sels = Selectors {
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kcode: gdt.add_entry(Descriptor::kernel_code_segment()),
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kdata: gdt.add_entry(Descriptor::kernel_data_segment()),
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tss: gdt.add_entry(Descriptor::tss_segment(&TSS)),
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};
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(gdt, sels)
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});
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