kernel/src/interrupts/gdt.rs


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61

use lazy_static::lazy_static;
use x86_64::structures::gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector};
use x86_64::structures::tss::TaskStateSegment;
use x86_64::VirtAddr;

pub const DOUBLE_FAULT_IST_INDEX: u16 = 0;
pub const PAGE_FAULT_IST_INDEX: u16 = 1;

lazy_static! {
    static ref TSS: TaskStateSegment = {
        let mut tss = TaskStateSegment::new();
        tss.interrupt_stack_table[DOUBLE_FAULT_IST_INDEX as usize] = {
            const STACK_SIZE: usize = 4096 * 4;
            static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];

            let stack_start = VirtAddr::from_ptr(unsafe { &STACK });
            let stack_end = stack_start + STACK_SIZE;
            stack_end
        };
        tss.interrupt_stack_table[PAGE_FAULT_IST_INDEX as usize] = {
            const STACK_SIZE: usize = 4096 * 8;
            static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];

            let stack_start = VirtAddr::from_ptr(unsafe { &STACK });
            let stack_end = stack_start + STACK_SIZE;
            stack_end
        };
        tss
    };
}

lazy_static! {
    static ref GDT: (GlobalDescriptorTable, Selectors) = {
        let mut gdt = GlobalDescriptorTable::new();
        let code_selector = gdt.add_entry(Descriptor::kernel_code_segment());
        let tss_selector = gdt.add_entry(Descriptor::tss_segment(&TSS));
        (
            gdt,
            Selectors {
                code_selector,
                tss_selector,
            },
        )
    };
}

struct Selectors {
    code_selector: SegmentSelector,
    tss_selector: SegmentSelector,
}

pub fn init() {
    use x86_64::instructions::segmentation::set_cs;
    use x86_64::instructions::tables::load_tss;

    GDT.0.load();
    unsafe {
        set_cs(GDT.1.code_selector);
        load_tss(GDT.1.tss_selector);
    }
}