Add 32-bit IDT types to second stage

Author: phil-opp

src/stage_2/src/idt.rs

@@ -0,0 +1,214 @@
+use core::marker::PhantomData;
+
+/// An Interrupt Descriptor Table with 32 entries.
+#[derive(Clone)]
+#[repr(C, align(16))]
+pub struct InterruptDescriptorTable {
+    pub divide_error: Entry<HandlerFunc>,
+    pub debug: Entry<HandlerFunc>,
+    pub non_maskable_interrupt: Entry<HandlerFunc>,
+    pub breakpoint: Entry<HandlerFunc>,
+    pub overflow: Entry<HandlerFunc>,
+    pub bound_range_exceeded: Entry<HandlerFunc>,
+    pub invalid_opcode: Entry<HandlerFunc>,
+    pub device_not_available: Entry<HandlerFunc>,
+    pub double_fault: Entry<DivergingHandlerFuncWithErrCode>,
+    coprocessor_segment_overrun: Entry<HandlerFunc>,
+    pub invalid_tss: Entry<HandlerFuncWithErrCode>,
+    pub segment_not_present: Entry<HandlerFuncWithErrCode>,
+    pub stack_segment_fault: Entry<HandlerFuncWithErrCode>,
+    pub general_protection_fault: Entry<HandlerFuncWithErrCode>,
+    pub page_fault: Entry<HandlerFuncWithErrCode>,
+    reserved_1: Entry<HandlerFunc>,
+    pub x87_floating_point: Entry<HandlerFunc>,
+    pub alignment_check: Entry<HandlerFuncWithErrCode>,
+    pub machine_check: Entry<DivergingHandlerFunc>,
+    pub simd_floating_point: Entry<HandlerFunc>,
+    pub virtualization: Entry<HandlerFunc>,
+    reserved_2: [Entry<HandlerFunc>; 9],
+    pub security_exception: Entry<HandlerFuncWithErrCode>,
+    reserved_3: Entry<HandlerFunc>,
+}
+
+impl InterruptDescriptorTable {
+    /// Creates a new IDT filled with non-present entries.
+    #[inline]
+    pub const fn new() -> InterruptDescriptorTable {
+        InterruptDescriptorTable {
+            divide_error: Entry::missing(),
+            debug: Entry::missing(),
+            non_maskable_interrupt: Entry::missing(),
+            breakpoint: Entry::missing(),
+            overflow: Entry::missing(),
+            bound_range_exceeded: Entry::missing(),
+            invalid_opcode: Entry::missing(),
+            device_not_available: Entry::missing(),
+            double_fault: Entry::missing(),
+            coprocessor_segment_overrun: Entry::missing(),
+            invalid_tss: Entry::missing(),
+            segment_not_present: Entry::missing(),
+            stack_segment_fault: Entry::missing(),
+            general_protection_fault: Entry::missing(),
+            page_fault: Entry::missing(),
+            reserved_1: Entry::missing(),
+            x87_floating_point: Entry::missing(),
+            alignment_check: Entry::missing(),
+            machine_check: Entry::missing(),
+            simd_floating_point: Entry::missing(),
+            virtualization: Entry::missing(),
+            reserved_2: [Entry::missing(); 9],
+            security_exception: Entry::missing(),
+            reserved_3: Entry::missing(),
+        }
+    }
+
+    /// Loads the IDT in the CPU using the `lidt` command.
+    pub fn load(&'static self) {
+        unsafe { self.load_unsafe() }
+    }
+
+    /// Loads the IDT in the CPU using the `lidt` command.
+    ///
+    /// # Safety
+    ///
+    /// As long as it is the active IDT, you must ensure that:
+    ///
+    /// - `self` is never destroyed.
+    /// - `self` always stays at the same memory location. It is recommended to wrap it in
+    /// a `Box`.
+    ///
+    pub unsafe fn load_unsafe(&self) {
+        use core::mem::size_of;
+
+        let ptr = DescriptorTablePointer {
+            base: self as *const _ as u32,
+            limit: (size_of::<Self>() - 1) as u16,
+        };
+
+        llvm_asm!("lidt ($0)" :: "r" (&ptr) : "memory");
+    }
+}
+
+/// A struct describing a pointer to a descriptor table (GDT / IDT).
+/// This is in a format suitable for giving to 'lgdt' or 'lidt'.
+#[derive(Debug, Clone, Copy)]
+#[repr(C, packed)]
+pub struct DescriptorTablePointer {
+    /// Size of the DT.
+    pub limit: u16,
+    /// Pointer to the memory region containing the DT.
+    pub base: u32,
+}
+
+/// An Interrupt Descriptor Table entry.
+///
+/// The generic parameter can either be `HandlerFunc` or `HandlerFuncWithErrCode`, depending
+/// on the interrupt vector.
+#[derive(Debug, Clone, Copy, PartialEq)]
+#[repr(C)]
+pub struct Entry<F> {
+    offset_low: u16,
+    gdt_selector: u16,
+    zero: u8,
+    options: EntryOptions,
+    offset_high: u16,
+    phantom: PhantomData<F>,
+}
+
+impl<F> Entry<F> {
+    /// Creates a non-present IDT entry (but sets the must-be-one bits).
+    #[inline]
+    pub const fn missing() -> Self {
+        Entry {
+            gdt_selector: 0,
+            offset_low: 0,
+            offset_high: 0,
+            zero: 0,
+            options: EntryOptions::minimal(),
+            phantom: PhantomData,
+        }
+    }
+    /// Set the handler address for the IDT entry and sets the present bit.
+    ///
+    /// For the code selector field, this function uses the code segment selector currently
+    /// active in the CPU.
+    ///
+    /// The function returns a mutable reference to the entry's options that allows
+    /// further customization.
+    #[inline]
+    fn set_handler_addr(&mut self, addr: u32) -> &mut EntryOptions {
+        self.offset_low = addr as u16;
+        self.offset_high = (addr >> 16) as u16;
+
+        let segment: u16;
+        unsafe { llvm_asm!("mov %cs, $0" : "=r" (segment) ) };
+
+        self.gdt_selector = segment;
+
+        self.options.set_present(true);
+        &mut self.options
+    }
+}
+
+macro_rules! impl_set_handler_fn {
+    ($h:ty) => {
+        impl Entry<$h> {
+            /// Set the handler function for the IDT entry and sets the present bit.
+            ///
+            /// For the code selector field, this function uses the code segment selector currently
+            /// active in the CPU.
+            ///
+            /// The function returns a mutable reference to the entry's options that allows
+            /// further customization.
+            #[inline]
+            pub fn set_handler_fn(&mut self, handler: $h) -> &mut EntryOptions {
+                self.set_handler_addr(handler as u32)
+            }
+        }
+    };
+}
+
+impl_set_handler_fn!(HandlerFunc);
+impl_set_handler_fn!(HandlerFuncWithErrCode);
+impl_set_handler_fn!(DivergingHandlerFunc);
+impl_set_handler_fn!(DivergingHandlerFuncWithErrCode);
+
+/// Represents the options field of an IDT entry.
+#[repr(transparent)]
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct EntryOptions(u8);
+
+impl EntryOptions {
+    /// Creates a minimal options field with all the must-be-one bits set.
+    #[inline]
+    const fn minimal() -> Self {
+        EntryOptions(0b1110)
+    }
+
+    /// Set or reset the preset bit.
+    #[inline]
+    pub fn set_present(&mut self, present: bool) -> &mut Self {
+        self.0.set_bit(15, present);
+        self
+    }
+}
+
+/// A handler function for an interrupt or an exception without error code.
+pub type HandlerFunc = extern "x86-interrupt" fn(&mut InterruptStackFrame);
+/// A handler function for an exception that pushes an error code.
+pub type HandlerFuncWithErrCode =
+    extern "x86-interrupt" fn(&mut InterruptStackFrame, error_code: u64);
+/// A handler function that must not return, e.g. for a machine check exception.
+pub type DivergingHandlerFunc = extern "x86-interrupt" fn(&mut InterruptStackFrame) -> !;
+/// A handler function with an error code that must not return, e.g. for a double fault exception.
+pub type DivergingHandlerFuncWithErrCode =
+    extern "x86-interrupt" fn(&mut InterruptStackFrame, error_code: u64) -> !;
+
+/// Represents the interrupt stack frame pushed by the CPU on interrupt or exception entry.
+#[derive(Clone)]
+#[repr(C)]
+pub struct InterruptStackFrame {
+    eip: u32,
+    cs: u32,
+    eflags: u32,
+}

src/stage_2/src/lib.rs

@@ -1,9 +1,14 @@
 #![no_std]
+#![feature(abi_x86_interrupt)]
+#![feature(const_fn)]
+#![feature(llvm_asm)]
 
 use shared::console::println;
 
+mod idt;
+
 #[no_mangle]
 pub fn second_stage() -> u16 {
-	println(b"Stage 2");
+    println(b"Stage 2");
     return 12345;
-}
+}