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use crate::segmentation::SegmentSelector;
use core::arch::asm;
use core::fmt;
use core::mem::size_of;
#[repr(C, packed)]
pub struct DescriptorTablePointer<Entry> {
pub limit: u16,
pub base: *const Entry,
}
impl<T> Default for DescriptorTablePointer<T> {
fn default() -> DescriptorTablePointer<T> {
DescriptorTablePointer {
limit: 0,
base: core::ptr::null(),
}
}
}
impl<T> DescriptorTablePointer<T> {
pub fn new(tbl: &T) -> Self {
let len = size_of::<T>() - 1;
assert!(len < 0x10000);
DescriptorTablePointer {
base: tbl as *const T,
limit: len as u16,
}
}
pub fn new_from_slice(slice: &[T]) -> Self {
let len = slice.len() * size_of::<T>() - 1;
assert!(len < 0x10000);
DescriptorTablePointer {
base: slice.as_ptr(),
limit: len as u16,
}
}
}
impl<T> fmt::Debug for DescriptorTablePointer<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "DescriptorTablePointer ({} {:?})", { self.limit }, {
self.base
})
}
}
pub unsafe fn lgdt<T>(gdt: &DescriptorTablePointer<T>) {
asm!("lgdt ({0})", in(reg) gdt, options(att_syntax));
}
pub unsafe fn sgdt<T>(idt: &mut DescriptorTablePointer<T>) {
asm!("sgdt ({0})", in(reg) idt as *mut DescriptorTablePointer<T>, options(att_syntax));
}
pub unsafe fn load_ldtr(selector: SegmentSelector) {
asm!("lldt {0:x}", in(reg) selector.bits(), options(att_syntax));
}
pub unsafe fn ldtr() -> SegmentSelector {
let selector: u16;
asm!("sldt {0:x}", out(reg) selector, options(att_syntax));
SegmentSelector::from_raw(selector)
}
pub unsafe fn lidt<T>(idt: &DescriptorTablePointer<T>) {
asm!("lidt ({0})", in(reg) idt, options(att_syntax));
}
pub unsafe fn sidt<T>(idt: &mut DescriptorTablePointer<T>) {
asm!("sidt ({0})", in(reg) idt as *mut DescriptorTablePointer<T>, options(att_syntax));
}
#[cfg(all(test, feature = "utest"))]
mod test {
use super::*;
#[test]
fn check_sgdt() {
let mut gdtr: super::DescriptorTablePointer<u64> = Default::default();
gdtr.limit = 0xdead;
gdtr.base = 0xbadc0de as *mut u64;
unsafe {
sgdt(&mut gdtr);
}
let base = gdtr.base;
let limit = gdtr.limit;
assert_ne!(base, core::ptr::null_mut());
assert_ne!(limit, 0xdead);
assert_ne!(base as u64, 0xbadc0de);
}
#[test]
fn check_sidt() {
let mut gdtr: super::DescriptorTablePointer<u64> = Default::default();
gdtr.limit = 0xdead;
gdtr.base = 0xbadc0de as *mut u64;
unsafe {
sidt(&mut gdtr);
}
let base = gdtr.base;
let limit = gdtr.limit;
assert_ne!(base, core::ptr::null_mut());
assert_ne!(limit, 0xdead);
assert_ne!(base as u64, 0xbadc0de);
}
}