From 825f900a37fbfa9c4c9f0e9dc080b56677f32155 Mon Sep 17 00:00:00 2001
From: Andri Saar <andrisaar@google.com>
Date: Tue, 24 May 2022 18:48:17 +0000
Subject: [PATCH] Start populating the IDT and handle double faults.

---
 experimental/uefi/kernel/src/interrupts.rs | 58 ++++++++++++++++++++++
 experimental/uefi/kernel/src/lib.rs        |  3 ++
 2 files changed, 61 insertions(+)
 create mode 100644 experimental/uefi/kernel/src/interrupts.rs

diff --git a/experimental/uefi/kernel/src/interrupts.rs b/experimental/uefi/kernel/src/interrupts.rs
new file mode 100644
index 00000000000..10da015937a
--- /dev/null
+++ b/experimental/uefi/kernel/src/interrupts.rs
@@ -0,0 +1,58 @@
+//
+// Copyright 2022 The Project Oak 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::i8042;
+use core::ops::Deref;
+use lazy_static::lazy_static;
+use log::error;
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
+
+lazy_static! {
+    static ref IDT: InterruptDescriptorTable = {
+        let mut idt = InterruptDescriptorTable::new();
+        idt.double_fault.set_handler_fn(double_fault_handler);
+        idt
+    };
+}
+
+extern "x86-interrupt" fn double_fault_handler(
+    stack_frame: InterruptStackFrame,
+    _error_code: u64,
+) -> ! {
+    // We're not calling `panic!` here because (a) the panic location would be all wrong (the error
+    // is not in the fault handler itself as the location would suggest), (b) in theory the
+    // panic handler itself could cause a double fault, and (c) we want to be sure that we shut
+    // down the machine after us.
+    // Note that for double fault handlers the error code will always be 0, so there's no point in
+    // logging that.
+    error!("KERNEL PANIC: DOUBLE FAULT");
+    error!(
+        "Instruction pointer: {:#016x}",
+        stack_frame.deref().instruction_pointer.as_u64()
+    );
+    error!("Code segment: {:#x}", stack_frame.deref().code_segment);
+    error!(
+        "Stack pointer: {:#016x}",
+        stack_frame.deref().stack_pointer.as_u64()
+    );
+    error!("Stack segment: {:#x}", stack_frame.deref().stack_segment);
+    error!("CPU flags: {:#x}", stack_frame.deref().cpu_flags);
+    i8042::shutdown();
+}
+
+pub fn init_idt() {
+    IDT.load();
+}
diff --git a/experimental/uefi/kernel/src/lib.rs b/experimental/uefi/kernel/src/lib.rs
index dec9cef59d2..ddd2eafe1fd 100644
--- a/experimental/uefi/kernel/src/lib.rs
+++ b/experimental/uefi/kernel/src/lib.rs
@@ -29,9 +29,11 @@
 //!   * Call `start_kernel` from the entry point of the bootloader.
 
 #![no_std]
+#![feature(abi_x86_interrupt)]
 
 mod avx;
 pub mod i8042;
+mod interrupts;
 mod libm;
 mod logging;
 mod memory;
@@ -45,6 +47,7 @@ use rust_hypervisor_firmware_subset::{boot, paging};
 pub fn start_kernel(info: &dyn boot::Info) -> ! {
     avx::enable_avx();
     logging::init_logging();
+    interrupts::init_idt();
     paging::setup();
     memory::init_allocator(info);
     main(info);