Interrupt

The Interrupt trait provides a way to enable and disable interrupts. It is defined in awkernel_lib/src/interrupt.rs as follows.

#![allow(unused)]
fn main() {
pub trait Interrupt {
    fn get_flag() -> usize;
    fn disable();
    fn enable();
    fn set_flag(flag: usize);
}
}

The get_flag and set_flag methods get and set the interrupt flag. These methods are used to save and restore the interrupt flag when enabling and disabling interrupts and used in the InterruptGuard structure.

Interrupt Guard

The InterruptGuard structure defined in awkernel_lib/src/interrupt.rs is used to disable interrupts in a scope. After the scope, interrupts are enabled automatically as follows.

#![allow(unused)]
fn main() {
{
    use awkernel_lib::interrupt::InterruptGuard;
    let _int_guard = InterruptGuard::new();
    // interrupts are disabled.
}
}

There are enable and disable functions in awkernel_lib/src/interrupt.rs. You can use these functions rather than using the InterruptGuard.

Implementation

x86_64

For x86_64, the X86 structure implements the Interrupt trait in awkernel_lib/src/arch/x86_64/interrupt.rs as follows.

#![allow(unused)]
fn main() {
impl Interrupt for super::X86 {
    fn get_flag() -> usize {
        if x86_64::instructions::interrupts::are_enabled() {
            1
        } else {
            0
        }
    }

    fn disable() {
        x86_64::instructions::interrupts::disable();
    }

    fn enable() {
        x86_64::instructions::interrupts::enable();
    }

    fn set_flag(flag: usize) {
        if flag == 0 {
            x86_64::instructions::interrupts::disable();
        } else {
            x86_64::instructions::interrupts::enable();
        }
    }
}
}

For x86_64, Awkernel uses the x86_64 crate to enable and disable interrupts.

AArch64

For x86_64, the AArch64 structure implements the Interrupt trait in awkernel_lib/src/arch/aarch64/interrupt.rs as follows.

#![allow(unused)]
fn main() {
impl Interrupt for super::AArch64 {
    fn get_flag() -> usize {
        awkernel_aarch64::daif::get() as usize
    }

    fn disable() {
        unsafe { core::arch::asm!("msr daifset, #0b0010",) };
    }

    fn enable() {
        unsafe { core::arch::asm!("msr daifclr, #0b0010",) };
    }

    fn set_flag(flag: usize) {
        unsafe { awkernel_aarch64::daif::set(flag as u64) };
    }
}
}