Add sidt support (#246)

Author: CraftSpider

src/asm/asm.s

@@ -119,6 +119,12 @@ _x86_64_asm_lidt:
     lidt (%rdi)
     retq
 
+.global _x86_64_asm_sidt
+.p2align 4
+_x86_64_asm_sidt:
+    sidt (%rdi)
+    retq
+
 .global _x86_64_asm_write_rflags
 .p2align 4
 _x86_64_asm_write_rflags:

src/asm/mod.rs

@@ -132,6 +132,12 @@ extern "C" {
     )]
     pub(crate) fn x86_64_asm_lidt(idt: *const crate::instructions::tables::DescriptorTablePointer);
 
+    #[cfg_attr(
+        any(target_env = "gnu", target_env = "musl"),
+        link_name = "_x86_64_asm_sidt"
+    )]
+    pub(crate) fn x86_64_asm_sidt(idt: *mut crate::instructions::tables::DescriptorTablePointer);
+
     #[cfg_attr(
         any(target_env = "gnu", target_env = "musl"),
         link_name = "_x86_64_asm_ltr"

src/instructions/tables.rs

@@ -1,6 +1,7 @@
 //! Functions to load GDT, IDT, and TSS structures.
 
 use crate::structures::gdt::SegmentSelector;
+use crate::VirtAddr;
 
 pub use crate::structures::DescriptorTablePointer;
 
@@ -44,6 +45,25 @@ pub unsafe fn lidt(idt: &DescriptorTablePointer) {
     crate::asm::x86_64_asm_lidt(idt as *const _);
 }
 
+/// Get the address of the current IDT.
+#[inline]
+pub fn sidt() -> DescriptorTablePointer {
+    let mut idt: DescriptorTablePointer = DescriptorTablePointer {
+        limit: 0,
+        base: VirtAddr::new(0),
+    };
+    #[cfg(feature = "inline_asm")]
+    unsafe {
+        asm!("sidt [{}]", in(reg) &mut idt, options(nostack));
+    }
+    #[cfg(not(feature = "inline_asm"))]
+    unsafe {
+        crate::asm::x86_64_asm_sidt(&mut idt as *mut _);
+    }
+
+    idt
+}
+
 /// Load the task state register using the `ltr` instruction.
 ///
 /// ## Safety