[interrupt-handlers] added IDT

- added IdtEntry structure,
- created IDT static mut array, and
- made fxns to init_idt and set_idt_entry.

Signed-off-by: danbugs <[email protected]>

Author: danbugs

src/hyperlight_guest/src/idt.rs

@@ -0,0 +1,90 @@
+/*
+Copyright 2024 The Hyperlight Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+use crate::interrupt_entry::{
+    _do_excp0, _do_excp1, _do_excp2, _do_excp3, _do_excp4, _do_excp5, _do_excp6, _do_excp7,
+    _do_excp8, _do_excp9, _do_excp10, _do_excp11, _do_excp12, _do_excp13, _do_excp14, _do_excp15,
+    _do_excp16, _do_excp17, _do_excp18, _do_excp19, _do_excp20, _do_excp30};
+
+// An entry in the Interrupt Descriptor Table (IDT)
+// For reference, see: https://wiki.osdev.org/Interrupt_Descriptor_Table#Structure_on_x86-64
+#[repr(C, align(16))]
+pub(crate) struct IdtEntry {
+    offset_low: u16,  // Lower 16 bits of handler address
+    selector: u16,    // code segment selector in GDT
+    ist: u8,          // Interrupt Stack Table offset
+    type_attr: u8,    // Gate type and flags
+    offset_mid: u16,  // Middle 16 bits of handler address
+    offset_high: u32, // High 32 bits of handler address
+    zero: u32,        // Reserved (always 0)
+}
+
+impl IdtEntry {
+    fn new(handler: u64) -> Self {
+        Self {
+            offset_low: (handler & 0xFFFF) as u16,
+            selector: 0x08,                             // Kernel Code Segment
+            ist: 0,                                     // No IST used
+            type_attr: 0x8E,
+            // 0x8E = 10001110b
+            // 1 00 0 1110
+            // 1 = Present
+            // 00 = Descriptor Privilege Level (0)
+            // 0 = Storage Segment (0)
+            // 1110 = Gate Type (0b1110 = 14 = 0xE)
+            // 0xE means it's an interrupt gate
+            offset_mid: ((handler >> 16) & 0xFFFF) as u16,
+            offset_high: ((handler >> 32) & 0xFFFFFFFF) as u32,
+            zero: 0,
+        }
+    }
+}
+
+
+// The IDT is an array of 256 IDT entries
+// (for reference, see: https://wiki.osdev.org/Interrupt_Descriptor_Table#Structure_on_x86-64)
+pub(crate) static mut IDT: [IdtEntry; 256] = unsafe { core::mem::zeroed() };
+
+pub(crate) fn init_idt() {
+    set_idt_entry(0, _do_excp0);    // Divide by zero
+    set_idt_entry(1, _do_excp1);    // Debug
+    set_idt_entry(2, _do_excp2);    // Non-maskable interrupt
+    set_idt_entry(3, _do_excp3);    // Breakpoint
+    set_idt_entry(4, _do_excp4);    // Overflow
+    set_idt_entry(5, _do_excp5);    // Bound Range Exceeded
+    set_idt_entry(6, _do_excp6);    // Invalid Opcode
+    set_idt_entry(7, _do_excp7);    // Device Not Available
+    set_idt_entry(8, _do_excp8);    // Double Fault
+    set_idt_entry(9, _do_excp9);    // Coprocessor Segment Overrun
+    set_idt_entry(10, _do_excp10);  // Invalid TSS
+    set_idt_entry(11, _do_excp11);  // Segment Not Present
+    set_idt_entry(12, _do_excp12);  // Stack-Segment Fault
+    set_idt_entry(13, _do_excp13);  // General Protection Fault
+    set_idt_entry(14, _do_excp14);  // Page Fault
+    set_idt_entry(15, _do_excp15);  // Reserved
+    set_idt_entry(16, _do_excp16);  // x87 Floating-Point Exception
+    set_idt_entry(17, _do_excp17);  // Alignment Check
+    set_idt_entry(18, _do_excp18);  // Machine Check
+    set_idt_entry(19, _do_excp19);  // SIMD Floating-Point Exception
+    set_idt_entry(20, _do_excp20);  // Virtualization Exception
+    set_idt_entry(30, _do_excp30);  // Security Exception
+}
+
+fn set_idt_entry(index: usize, handler: unsafe extern "sysv64" fn()) {
+    let handler_addr = handler as *const () as u64;
+    unsafe { IDT[index] = IdtEntry::new(handler_addr); }
+}
+

src/hyperlight_guest/src/lib.rs

@@ -53,6 +53,7 @@ pub mod error;
 pub mod logging;
 pub mod interrupt_entry;
 pub mod interrupt_handlers;
+pub mod idt;
 
 // Unresolved symbols
 ///cbindgen:ignore