加载GDT时出现三重故障

Question

我试图在铁锈和全球asm中设置GDT，但当我尝试加载GDT时，它似乎是三重故障。

# init_gdt.asm.
.intel_syntax noprefix

# **Notes**: 0x00: The Kernel Null Segment.
#            0x10: The Kernel Data Segment.
#            0x08: The Kernel Code Segment.

# Load the GDT and set all of the segments.
LoadGDT:
    # Use the `lgdt` Load GDT instruction to set the new GDT.
    # The rdi register contains the first argument of the function.
    lgdt [rdi]

    mov ax, 0x10
    
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax
    mov ss, ax

    pop rdi
    
    mov rax, 0x08
    
    push rax
    push rdi
    
    retfq

.global LoadGDT

global_asm!(include_str!("load_gdt.asm"));

#[repr(C, packed)]
struct GDTDescriptor {
    size: u16,
    offset: u64,
}

impl GDTDescriptor {
    #[inline]
    pub fn new(size: u16, offset: u64) -> Self {
        Self { size, offset }
    }
}

#[repr(C)]
struct GDTEntry {
    limit_low: u16,
    base_low: u16,
    base_middle: u8,
    access_byte: u8,
    limit_hi_flags: u8,
    base_hi: u8,
}

impl GDTEntry {
    #[inline]
    fn new(
        limit_low: u16,
        base_low: u16,
        base_middle: u8,
        access_byte: u8,
        limit_hi_flags: u8,
        base_hi: u8,
    ) -> Self {
        Self {
            limit_low,
            base_low,
            base_middle,
            access_byte,
            limit_hi_flags,
            base_hi,
        }
    }
}

/// The GDT.
#[repr(C, align(0x1000))]
struct GDT {
    kernel_null: GDTEntry,
    kernel_code: GDTEntry,
    kernel_data: GDTEntry,
    user_null: GDTEntry,
    user_code: GDTEntry,
    user_data: GDTEntry,
}

/// Initialize the GDT.
pub fn init() {
    unsafe {
        let gdt_descriptor = GDTDescriptor::new(
            (size_of::<GDT>() - 1) as u16,
            (&GLOBAL_DESCRIPTOR_TABLE as *const _) as u64,
        );

        LoadGDT(&gdt_descriptor as *const _)
    }
}

lazy_static! {
    /// The GDT (Global Descriptor Table).
    static ref GLOBAL_DESCRIPTOR_TABLE: GDT = GDT {
        kernel_null: GDTEntry::new(0, 0, 0, 0x00, 0x00, 0),
        kernel_code: GDTEntry::new(0, 0, 0, 0x9a, 0xa0, 0),
        kernel_data: GDTEntry::new(0, 0, 0, 0x92, 0xa0, 0),
        user_null: GDTEntry::new(0, 0, 0, 0x00, 0x00, 0),
        user_code: GDTEntry::new(0, 0, 0, 0x9a, 0xa0, 0),
        user_data: GDTEntry::new(0, 0, 0, 0x92, 0xa0, 0)
    };
}

根据qemu日志，它发生在mov ds, ax指令中。我遵循了osdev.org指令，我确信我的程序集是完全有效的。

我也一直试图改变和尝试一些随机的GDTEntries，看看它们是否有效，但在这里没有运气。

存储库：https://github.com/Andy-Python-Programmer/aero

Answer 1

我不知道这是一个简单的答案！我只需考虑(*) GDT，因为它是惰性的静态的，这解决了一切:D