From 496ccaaf750a4ec1c537c463eff56108e1cc0bb4 Mon Sep 17 00:00:00 2001
From: Dennis Kobert <dennis@kobert.dev>
Date: Sun, 18 Apr 2021 19:01:54 +0200
Subject: Further cleanup

* Bump x86_64 dep to version 0.1.14
* Rewrite LOCAL_APIC handling
* Remove warnings
---
 kernel/Cargo.toml                           |  2 +-
 kernel/src/interrupts/apic.rs               | 67 +++++++++++++++++++++--------
 kernel/src/interrupts/exception_handlers.rs | 17 +++++---
 kernel/src/interrupts/gdt.rs                |  6 +--
 kernel/src/interrupts/idt.rs                |  2 +-
 kernel/src/interrupts/interrupt_handlers.rs |  8 ++--
 kernel/src/io/panic_screen.rs               |  3 +-
 kernel/src/io/serial.rs                     |  1 +
 kernel/src/io/vga_text.rs                   | 13 +++---
 kernel/src/lib.rs                           | 14 ++++++
 kernel/src/main.rs                          | 12 ++++--
 kernel/src/testing/panic.rs                 |  1 +
 kernel/tests/boot.rs                        |  4 ++
 kernel/tests/int3.rs                        |  8 +++-
 kernel/tests/stack_overflow.rs              |  4 +-
 15 files changed, 114 insertions(+), 48 deletions(-)

diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml
index bce79cb..25bce57 100644
--- a/kernel/Cargo.toml
+++ b/kernel/Cargo.toml
@@ -17,7 +17,7 @@ harness = false
 testing_qemu = []
 
 [dependencies]
-x86_64 = "0.13"
+x86_64 = "0.14"
 uart_16550 = "0.2.1"
 spin = "0.5"
 
diff --git a/kernel/src/interrupts/apic.rs b/kernel/src/interrupts/apic.rs
index 0e89943..836af20 100644
--- a/kernel/src/interrupts/apic.rs
+++ b/kernel/src/interrupts/apic.rs
@@ -1,8 +1,11 @@
+use core::sync::atomic::{AtomicU64, Ordering};
 use x86_64::registers::model_specific::Msr;
 
 #[cfg(target_arch = "x86_64")]
 const APIC_FLAG: u64 = 0x0800;
 const APIC_BASE_MSR: u32 = 0x001b;
+const CPU_COUNT: usize = 255;
+const APIC_BASE_ADDR: u64 = 0xfee0_0000;
 
 // APIC constant register values
 const APIC_DISABLE: u32 = 0x0001_0000;
@@ -20,8 +23,13 @@ pub fn is_apic() -> bool {
     info & (1 << 9) != 0
 }
 
-pub fn set_apic_base(v: u64) {
-    unsafe { Msr::new(APIC_BASE_MSR).write(v) }
+pub fn cpu_id() -> u32 {
+    let mut info: u32;
+    unsafe { asm!("cpuid", inout("eax") 1 => _, out("ebx") info) }
+    if !is_x2apic() {
+        info >>= 24;
+    }
+    info
 }
 
 #[repr(C)]
@@ -75,27 +83,48 @@ pub enum TimerDivideConfig {
     Div128 = 10,
     NoDivide = 11,
 }
+const NONE_APIC: Option<Apic> = None;
 
-static mut LOCAL_APIC: Option<Apic> = None;
+static mut APIC_INIT: [Option<Apic>; CPU_COUNT] = [NONE_APIC; CPU_COUNT];
 
-pub unsafe fn set_local_apic(apic: Apic) -> &'static mut Apic {
-    LOCAL_APIC = Some(apic);
-    LOCAL_APIC.as_mut().unwrap()
+pub fn move_local_apic(v: u64) -> bool {
+    match get_local_apic() {
+        None => return false,
+        Some(apic) => apic.regs.store(v, Ordering::Release),
+    }
+    unsafe { Msr::new(APIC_BASE_MSR).write(v) };
+    true
 }
 
-pub unsafe fn get_local_apic() -> Option<&'static mut Apic> {
-    LOCAL_APIC.as_mut()
+/// Tries to initialize the local apic at it's default location.
+/// returns false if no apic is available
+///
+/// # Safety
+/// Calling this function in a running system might cause the loss of interrupts or other weird
+/// behaviour
+pub unsafe fn try_initialize_local_apic() -> &'static mut Option<Apic> {
+    if is_apic() {
+        let cpu_id = cpu_id() as usize;
+        if APIC_INIT[cpu_id].is_none() {
+            APIC_INIT[cpu_id] = Some(Apic::from_base_apic(APIC_BASE_ADDR));
+            Apic::disable_pic();
+        }
+        APIC_INIT[cpu_id].as_mut().map(|x| x.initialize());
+    }
+    get_local_apic()
+}
+
+pub fn get_local_apic() -> &'static mut Option<Apic> {
+    let cpu_id = cpu_id() as usize;
+    unsafe { &mut APIC_INIT[cpu_id] }
 }
 
 pub struct Apic {
-    regs: *mut [u32; 1024],
+    regs: AtomicU64,
 }
 
 impl Apic {
-    pub fn new() -> Option<Self> {
-        if !is_apic() {
-            return None;
-        }
+    fn initialize(&mut self) -> Self {
         Self::disable_pic();
         let base_apic = unsafe { Msr::new(APIC_BASE_MSR).read() };
         let mut apic = Self::from_base_apic(base_apic);
@@ -118,28 +147,28 @@ impl Apic {
 
         apic.set(ApicRegister::SpuriousInterruptVec, 0x1ff);
 
-        Some(apic)
+        apic
     }
 
-    pub fn disable_pic() {
+    fn disable_pic() {
         unsafe {
             x86_64::instructions::port::PortWriteOnly::new(0xa1).write(0xffu8);
             x86_64::instructions::port::PortWriteOnly::new(0x21).write(0xffu8);
         }
     }
 
-    fn from_base_apic(base_apic: u64) -> Self {
+    const fn from_base_apic(base_apic: u64) -> Self {
         Self {
-            regs: ((base_apic) & 0xfffffffff << 12) as *mut [u32; 1024],
+            regs: AtomicU64::new((base_apic) & 0xfffffffff << 12),
         }
     }
 
     pub fn ptr(&self) -> *const u32 {
-        self.regs as *const u32
+        self.regs.load(Ordering::Acquire) as *const u32
     }
 
     fn ptr_mut(&mut self) -> *mut u32 {
-        self.regs as *mut u32
+        self.regs.load(Ordering::SeqCst) as *mut u32
     }
 
     pub fn get(&self, register: ApicRegister) -> u32 {
diff --git a/kernel/src/interrupts/exception_handlers.rs b/kernel/src/interrupts/exception_handlers.rs
index ce8f6c0..db081a7 100644
--- a/kernel/src/interrupts/exception_handlers.rs
+++ b/kernel/src/interrupts/exception_handlers.rs
@@ -15,6 +15,11 @@ macro_rules! exception_default {
 
 static mut EXPECTED_FAULT: InterruptType = InterruptType::None;
 
+/// Set an exception that causes the kernel to exit with status success
+/// This is used for testing
+///
+/// # Safety
+/// This function may only be called before executing any kernel code
 pub unsafe fn expect_fault(int: InterruptType) {
     if EXPECTED_FAULT == InterruptType::None {
         EXPECTED_FAULT = int;
@@ -25,7 +30,7 @@ fn get_expected_fault() -> InterruptType {
     unsafe { EXPECTED_FAULT }
 }
 
-pub extern "x86-interrupt" fn breakpoint_handler(stack_frame: &mut InterruptStackFrame) {
+pub extern "x86-interrupt" fn breakpoint_handler(stack_frame: InterruptStackFrame) {
     match get_expected_fault() {
         InterruptType::Breakpoint => qemu::exit_qemu(qemu::QemuExitCode::Success),
         _ => panic!(
@@ -35,7 +40,7 @@ pub extern "x86-interrupt" fn breakpoint_handler(stack_frame: &mut InterruptStac
     }
 }
 
-pub extern "x86-interrupt" fn div_zero_handler(stack_frame: &mut InterruptStackFrame) {
+pub extern "x86-interrupt" fn div_zero_handler(stack_frame: InterruptStackFrame) {
     match get_expected_fault() {
         InterruptType::DivZero => qemu::exit_qemu(qemu::QemuExitCode::Success),
         _ => panic!(
@@ -46,7 +51,7 @@ pub extern "x86-interrupt" fn div_zero_handler(stack_frame: &mut InterruptStackF
 }
 
 pub extern "x86-interrupt" fn general_protection_fault_handler(
-    stack_frame: &mut InterruptStackFrame,
+    stack_frame: InterruptStackFrame,
     error_code: u64,
 ) {
     match get_expected_fault() {
@@ -60,7 +65,7 @@ pub extern "x86-interrupt" fn general_protection_fault_handler(
 }
 
 pub extern "x86-interrupt" fn page_fault_handler(
-    stack_frame: &mut InterruptStackFrame,
+    stack_frame: InterruptStackFrame,
     error_code: PageFaultErrorCode,
 ) {
     use x86_64::registers::control::Cr2;
@@ -78,7 +83,7 @@ pub extern "x86-interrupt" fn page_fault_handler(
 }
 
 pub extern "x86-interrupt" fn segment_not_present_handler(
-    stack_frame: &mut InterruptStackFrame,
+    stack_frame: InterruptStackFrame,
     error_code: u64,
 ) {
     match get_expected_fault() {
@@ -92,7 +97,7 @@ pub extern "x86-interrupt" fn segment_not_present_handler(
 }
 
 pub extern "x86-interrupt" fn double_fault_handler(
-    stack_frame: &mut InterruptStackFrame,
+    stack_frame: InterruptStackFrame,
     _error_code: u64, // code is always zero
 ) -> ! {
     match get_expected_fault() {
diff --git a/kernel/src/interrupts/gdt.rs b/kernel/src/interrupts/gdt.rs
index d75ff68..c20eabe 100644
--- a/kernel/src/interrupts/gdt.rs
+++ b/kernel/src/interrupts/gdt.rs
@@ -14,16 +14,14 @@ lazy_static! {
             static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];
 
             let stack_start = VirtAddr::from_ptr(unsafe { &STACK });
-            let stack_end = stack_start + STACK_SIZE;
-            stack_end
+            stack_start + STACK_SIZE
         };
         tss.interrupt_stack_table[PAGE_FAULT_IST_INDEX as usize] = {
             const STACK_SIZE: usize = 4096 * 8;
             static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];
 
             let stack_start = VirtAddr::from_ptr(unsafe { &STACK });
-            let stack_end = stack_start + STACK_SIZE;
-            stack_end
+            stack_start + STACK_SIZE
         };
         tss
     };
diff --git a/kernel/src/interrupts/idt.rs b/kernel/src/interrupts/idt.rs
index 4e5dd77..6bc8149 100644
--- a/kernel/src/interrupts/idt.rs
+++ b/kernel/src/interrupts/idt.rs
@@ -34,7 +34,7 @@ lazy_static! {
 }
 
 pub extern "x86-interrupt" fn dummy_handler(
-    _stack_frame: &mut x86_64::structures::idt::InterruptStackFrame,
+    _stack_frame: x86_64::structures::idt::InterruptStackFrame,
 ) {
     panic!("unhandled interrupt recieved");
 }
diff --git a/kernel/src/interrupts/interrupt_handlers.rs b/kernel/src/interrupts/interrupt_handlers.rs
index 831211b..8b3a7eb 100644
--- a/kernel/src/interrupts/interrupt_handlers.rs
+++ b/kernel/src/interrupts/interrupt_handlers.rs
@@ -2,18 +2,18 @@ use core::fmt::Write;
 use x86_64::structures::idt::InterruptStackFrame;
 use x86_64::structures::port;
 
-pub extern "x86-interrupt" fn timer_handler(_stack_frame: &mut InterruptStackFrame) {
+pub extern "x86-interrupt" fn timer_handler(_stack_frame: InterruptStackFrame) {
     crate::io::vga_text::OStream::new().print(b"Timer");
 
-    if let Some(apic) = unsafe { super::apic::get_local_apic() } {
+    if let Some(apic) = super::apic::get_local_apic() {
         apic.end_of_interrupt()
     }
 }
 
-pub extern "x86-interrupt" fn keyboard_handler(_stack_frame: &mut InterruptStackFrame) {
+pub extern "x86-interrupt" fn keyboard_handler(_stack_frame: InterruptStackFrame) {
     let code: u8 = unsafe { port::PortRead::read_from_port(0x60) };
     let _ = write!(crate::io::vga_text::OStream::new(), "{}", code);
-    if let Some(apic) = unsafe { super::apic::get_local_apic() } {
+    if let Some(apic) = super::apic::get_local_apic() {
         apic.end_of_interrupt()
     }
 }
diff --git a/kernel/src/io/panic_screen.rs b/kernel/src/io/panic_screen.rs
index 7b81676..35fe625 100644
--- a/kernel/src/io/panic_screen.rs
+++ b/kernel/src/io/panic_screen.rs
@@ -23,7 +23,8 @@ impl<'a> core::fmt::Write for TextBuffer<'a> {
         } else {
             let s = s.as_bytes();
             (&mut self.dst[self.len..self.len + s.len()]).clone_from_slice(s);
-            Ok(self.len += s.len())
+            self.len += s.len();
+            Ok(())
         }
     }
 }
diff --git a/kernel/src/io/serial.rs b/kernel/src/io/serial.rs
index 3f661e9..56bfbb3 100644
--- a/kernel/src/io/serial.rs
+++ b/kernel/src/io/serial.rs
@@ -12,6 +12,7 @@ lazy_static! {
     };
 }
 
+#[derive(Default)]
 pub struct SerialStream {}
 
 impl SerialStream {
diff --git a/kernel/src/io/vga_text.rs b/kernel/src/io/vga_text.rs
index 72c4d85..f9c15ad 100644
--- a/kernel/src/io/vga_text.rs
+++ b/kernel/src/io/vga_text.rs
@@ -27,12 +27,12 @@ pub const HEIGHT: usize = 25;
 pub struct CharState(pub u8);
 
 impl CharState {
-    pub fn from_colors(fg: Color, bg: Color) -> Self {
+    pub const fn from_colors(fg: Color, bg: Color) -> Self {
         Self((fg as u8) | ((bg as u8) << 4))
     }
 
     pub fn set_fg(&mut self, fg: Color) {
-        self.0 = (self.0 & (HEIGHT as u8) - 10) | (fg as u8)
+        self.0 = (self.0 & ((HEIGHT as u8) - 10)) | (fg as u8)
     }
 
     pub fn set_bg(&mut self, bg: Color) {
@@ -49,7 +49,7 @@ pub struct VgaChar {
 
 impl VgaChar {
     pub fn from_state_and_byte(state: CharState, byte: u8) -> Self {
-        Self { state, byte }
+        Self { byte, state }
     }
 }
 
@@ -61,7 +61,7 @@ pub struct OStream {
 }
 
 impl OStream {
-    pub fn new() -> Self {
+    pub const fn new() -> Self {
         Self {
             pos: (0, 0),
             cursor: Self::at(0),
@@ -70,7 +70,7 @@ impl OStream {
         }
     }
 
-    fn at(n: usize) -> *mut VgaChar {
+    const fn at(n: usize) -> *mut VgaChar {
         (0xb8000 + (n << 1)) as *mut VgaChar
     }
 
@@ -172,6 +172,7 @@ impl OStream {
 
 impl core::fmt::Write for OStream {
     fn write_str(&mut self, s: &str) -> core::fmt::Result {
-        Ok(self.print(s.as_bytes()))
+        self.print(s.as_bytes());
+        Ok(())
     }
 }
diff --git a/kernel/src/lib.rs b/kernel/src/lib.rs
index f03ef36..a8be053 100644
--- a/kernel/src/lib.rs
+++ b/kernel/src/lib.rs
@@ -1,3 +1,4 @@
+#![allow(unused_attributes)]
 #![no_main]
 #![feature(custom_test_frameworks)]
 #![feature(abi_x86_interrupt)]
@@ -21,6 +22,7 @@ pub use qemu::*;
 pub extern "C" fn _start() -> ! {
     init();
     test_main();
+    #[allow(clippy::empty_loop)]
     loop {}
 }
 
@@ -33,4 +35,16 @@ fn panic(info: &core::panic::PanicInfo) -> ! {
 pub fn init() {
     interrupts::gdt::init();
     interrupts::idt::init();
+    let apic = unsafe {
+        interrupts::apic::try_initialize_local_apic()
+            .as_mut()
+            .expect("no APIC support")
+    };
+
+    apic.set_timer_interrupt_handler(
+        interrupts::apic::TimerDivideConfig::Div16,
+        interrupts::InterruptType::Timer,
+    );
+
+    x86_64::instructions::interrupts::enable();
 }
diff --git a/kernel/src/main.rs b/kernel/src/main.rs
index 50b281f..017f4b9 100644
--- a/kernel/src/main.rs
+++ b/kernel/src/main.rs
@@ -19,8 +19,12 @@ extern "C" fn _start() -> ! {
     interrupts::gdt::init();
     interrupts::idt::init();
 
-    let apic = interrupts::apic::Apic::new().expect("no APIC support");
-    let apic = unsafe { interrupts::apic::set_local_apic(apic) };
+    loop {}
+    let apic = unsafe {
+        interrupts::apic::try_initialize_local_apic()
+            .as_mut()
+            .expect("no APIC support")
+    };
 
     apic.set_timer_interrupt_handler(
         interrupts::apic::TimerDivideConfig::Div16,
@@ -31,11 +35,13 @@ extern "C" fn _start() -> ! {
 
     let mut stdout = OStream::new();
     stdout.print(b"apic initialisation complete\n");
-    x86_64::instructions::interrupts::int3();
+    //x86_64::instructions::interrupts::int3();
+    stdout.print(b"foolete\n");
 
     if cfg!(test) {
         qemu::exit_qemu(qemu::QemuExitCode::Success);
     }
+    #[allow(clippy::empty_loop)]
     loop {}
 }
 
diff --git a/kernel/src/testing/panic.rs b/kernel/src/testing/panic.rs
index 11469f2..7dad694 100644
--- a/kernel/src/testing/panic.rs
+++ b/kernel/src/testing/panic.rs
@@ -33,5 +33,6 @@ pub fn should_panic(_info: &PanicInfo) -> ! {
 pub fn panic(info: &PanicInfo) -> ! {
     interrupts::disable();
     crate::io::panic_screen::show(info.message());
+    #[allow(clippy::empty_loop)]
     loop {}
 }
diff --git a/kernel/tests/boot.rs b/kernel/tests/boot.rs
index 3a65ff6..c6c0de0 100644
--- a/kernel/tests/boot.rs
+++ b/kernel/tests/boot.rs
@@ -4,6 +4,7 @@
 #![feature(panic_info_message)]
 #![test_runner(kernel::testing::serial_test_runner)]
 #![reexport_test_harness_main = "test_main"]
+#![allow(unreachable_code)]
 #![no_std]
 
 use kernel;
@@ -14,6 +15,7 @@ extern "C" fn _start() -> ! {
     kernel::init();
     test_main();
 
+    #[allow(clippy::empty_loop)]
     loop {}
 }
 
@@ -25,6 +27,7 @@ fn boot() {
 #[test_case]
 fn poweroff() {
     qemu::exit_qemu(qemu::QemuExitCode::Success);
+    loop {}
     panic!("Qemu did not exit");
 }
 
@@ -33,5 +36,6 @@ fn poweroff() {
 #[no_mangle]
 extern "C" fn panic_handler(info: &core::panic::PanicInfo) -> ! {
     kernel::testing::serial_panic(info);
+    #[allow(clippy::empty_loop)]
     loop {}
 }
diff --git a/kernel/tests/int3.rs b/kernel/tests/int3.rs
index faa5b3d..ac0e5f0 100644
--- a/kernel/tests/int3.rs
+++ b/kernel/tests/int3.rs
@@ -1,12 +1,15 @@
 #![no_main]
 #![feature(abi_x86_interrupt)]
 #![feature(panic_info_message)]
+#![allow(unreachable_code)]
+#![feature(custom_test_frameworks)]
+#![test_runner(kernel::testing::serial_test_runner)]
 #![no_std]
 
 use kernel;
 use kernel::interrupts;
 use kernel::interrupts::exception_handlers;
-use kernel::io::qemu;
+use kernel::qemu;
 
 #[no_mangle]
 extern "C" fn _start() -> ! {
@@ -15,6 +18,7 @@ extern "C" fn _start() -> ! {
         exception_handlers::expect_fault(interrupts::InterruptType::Breakpoint);
     }
     x86_64::instructions::interrupts::int3();
+
     panic!("BREAKPOINT not caught");
 
     loop {}
@@ -24,6 +28,6 @@ extern "C" fn _start() -> ! {
 #[panic_handler]
 #[no_mangle]
 extern "C" fn panic_handler(info: &core::panic::PanicInfo) -> ! {
-    kernel::testing::serial_should_panic(info);
+    kernel::testing::serial_panic(info);
     loop {}
 }
diff --git a/kernel/tests/stack_overflow.rs b/kernel/tests/stack_overflow.rs
index fc93376..9c4db19 100644
--- a/kernel/tests/stack_overflow.rs
+++ b/kernel/tests/stack_overflow.rs
@@ -2,12 +2,13 @@
 #![feature(abi_x86_interrupt)]
 #![feature(panic_info_message)]
 #![no_std]
+#![allow(unreachable_code)]
 
 use core::fmt::Write;
 use kernel;
 use kernel::interrupts;
 use kernel::interrupts::exception_handlers;
-use kernel::io::qemu;
+use kernel::qemu;
 
 #[no_mangle]
 extern "C" fn _start() -> ! {
@@ -15,6 +16,7 @@ extern "C" fn _start() -> ! {
     unsafe {
         exception_handlers::expect_fault(interrupts::InterruptType::PageFault);
     }
+    qemu::exit_qemu(qemu::QemuExitCode::Success);
     _loop(0);
     panic!("PAGE_FAULT not caught");
     loop {}
-- 
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