Initial commit

src/arch/mod.rs

@@ -0,0 +1,5 @@
+#[cfg(target_arch = "x86_64")]
+mod x86_64;
+
+#[cfg(target_arch = "x86_64")]
+pub use x86_64::*;

src/arch/x86_64/linker.ld

@@ -0,0 +1,77 @@
+/* Tell the linker that we want an x86_64 ELF64 output file */
+OUTPUT_FORMAT(elf64-x86-64)
+OUTPUT_ARCH(i386:x86-64)
+
+/* We want the symbol _start to be our entry point */
+ENTRY(_start)
+
+/* Define the program headers we want so the bootloader gives us the right */
+/* MMU permissions; this also allows us to exert more control over the linking */
+/* process. */
+PHDRS
+{
+    headers PT_PHDR PHDRS;
+    text    PT_LOAD FILEHDR PHDRS;
+    rodata  PT_LOAD;
+    data    PT_LOAD;
+    dynamic PT_DYNAMIC;
+}
+
+SECTIONS
+{
+    /* We want to be placed in the topmost 2GiB of the address space, for optimisations */
+    /* and because that is what the Limine spec mandates. */
+    /* Any address in this region will do, but often 0xffffffff80000000 is chosen as */
+    /* that is the beginning of the region. */
+    /* Additionally, leave space for the ELF headers by adding SIZEOF_HEADERS to the */
+    /* base load address. */
+    . = 0xffffffff80000000 + SIZEOF_HEADERS;
+
+    .text : {
+        *(.text .text.*)
+    } :text
+
+    /* Move to the next memory page for .rodata */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .rodata : {
+        *(.rodata .rodata.*)
+    } :rodata
+
+    /* Move to the next memory page for .data */
+    . = ALIGN(CONSTANT(MAXPAGESIZE));
+
+    .data : {
+        *(.data .data.*)
+
+        /* Place the sections that contain the Limine requests as part of the .data */
+        /* output section. */
+        KEEP(*(.requests_start_marker))
+        KEEP(*(.requests))
+        KEEP(*(.requests_end_marker))
+    } :data
+
+    /* Dynamic section for relocations, both in its own PHDR and inside data PHDR. */
+    .dynamic : {
+        *(.dynamic)
+    } :data :dynamic
+
+    /* NOTE: .bss needs to be the last thing mapped to :data, otherwise lots of */
+    /* unnecessary zeros will be written to the binary. */
+    /* If you need, for example, .init_array and .fini_array, those should be placed */
+    /* above this. */
+    .bss : {
+        *(.bss .bss.*)
+        *(COMMON)
+    } :data
+
+    /* Discard .note.* and .eh_frame* since they may cause issues on some hosts. */
+    /* Also discard the program interpreter section since we do not need one. This is */
+    /* more or less equivalent to the --no-dynamic-linker linker flag, except that it */
+    /* works with ld.gold. */
+    /DISCARD/ : {
+        *(.eh_frame*)
+        *(.note .note.*)
+        *(.interp)
+    }
+}

src/arch/x86_64/mod.rs

@@ -0,0 +1 @@
+pub mod port;

src/arch/x86_64/port.rs

@@ -0,0 +1,105 @@
+use core::arch::asm;
+
+#[inline(always)]
+pub unsafe fn read_u8(port: u16) -> u8 {
+    let value: u8;
+    unsafe {
+        asm!(
+            "in al, dx",
+            in("dx") port,
+            out("al") value,
+            options(nomem, nostack, preserves_flags),
+        );
+    }
+    value
+}
+
+#[inline(always)]
+pub unsafe fn read_u8_slice(port: u16, slice: &mut [u8]) {
+    unsafe {
+        asm!(
+            "rep insb",
+            in("dx") port,
+            inout("rdi") slice.as_mut_ptr() => _,
+            inout("rcx") slice.len() => _,
+            options(nostack, preserves_flags),
+        );
+    }
+}
+
+#[inline(always)]
+pub unsafe fn read_u16(port: u16) -> u16 {
+    let value: u16;
+    unsafe {
+        asm!(
+            "in ax, dx",
+            in("dx") port,
+            out("ax") value,
+            options(nomem, nostack, preserves_flags),
+        );
+    }
+    value
+}
+
+#[inline(always)]
+pub unsafe fn read_u32(port: u16) -> u32 {
+    let value: u32;
+    unsafe {
+        asm!(
+            "in eax, dx",
+            in("dx") port,
+            out("eax") value,
+            options(nomem, nostack, preserves_flags),
+        );
+    }
+    value
+}
+
+#[inline(always)]
+pub unsafe fn write_u8(port: u16, value: u8) {
+    unsafe {
+        asm!(
+            "out dx, al",
+            in("dx") port,
+            in("al") value,
+            options(nomem, nostack, preserves_flags),
+        );
+    }
+}
+
+#[inline(always)]
+pub unsafe fn write_u8_slice(port: u16, slice: &[u8]) {
+    unsafe {
+        asm!(
+            "rep outsb",
+            in("dx") port,
+            inout("rsi") slice.as_ptr() => _,
+            inout("rcx") slice.len() => _,
+            options(nostack, preserves_flags),
+        );
+    }
+}
+
+#[inline(always)]
+pub unsafe fn write_u16(port: u16, value: u16) {
+    unsafe {
+        asm!(
+            "out dx, ax",
+            in("dx") port,
+            in("ax") value,
+            options(nomem, nostack, preserves_flags),
+        );
+    }
+}
+
+#[inline(always)]
+pub unsafe fn write_u32(port: u16, value: u32) {
+    unsafe {
+        asm!(
+            "out dx, eax",
+            in("dx") port,
+            in("eax") value,
+            options(nomem, nostack, preserves_flags),
+        );
+    }
+}

src/arch/x86_64/x86_64-unknown-none.json

@@ -0,0 +1,20 @@
+{
+  "arch": "x86_64",
+  "cpu": "x86-64",
+  "data-layout": "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128",
+  "llvm-target": "x86_64-unknown-none",
+  "target-endian": "little",
+  "target-pointer-width": 64,
+  "target-c-int-width": 32,
+  "features": "-mmx,-sse,+soft-float",
+  "rustc-abi": "softfloat",
+  "os": "DawnOS",
+  "linker": "rust-lld",
+  "linker-flavor": "ld.lld",
+  "pre-link-args": {
+    "ld.lld": ["-melf_x86_64", "--script=./src/arch/x86_64/linker.ld"]
+  },
+  "panic-strategy": "abort",
+  "exe-suffix": ".elf",
+  "disable-redzone": true
+}

src/boot/limine.rs

@@ -0,0 +1,22 @@
+use limine::request::FramebufferRequest;
+use limine::{BaseRevision, RequestsEndMarker, RequestsStartMarker};
+
+/// Sets the base revision to the latest revision supported by the crate.
+/// See specification for further info.
+/// Be sure to mark all limine requests with #[used], otherwise they may be removed by the compiler.
+#[used]
+// The .requests section allows limine to find the requests faster and more safely.
+#[unsafe(link_section = ".requests")]
+pub static BASE_REVISION: BaseRevision = BaseRevision::new();
+
+#[used]
+#[unsafe(link_section = ".requests")]
+pub static FRAMEBUFFER_REQUEST: FramebufferRequest = FramebufferRequest::new();
+
+/// Define the stand and end markers for Limine requests.
+#[used]
+#[unsafe(link_section = ".requests_start_marker")]
+static _START_MARKER: RequestsStartMarker = RequestsStartMarker::new();
+#[used]
+#[unsafe(link_section = ".requests_end_marker")]
+static _END_MARKER: RequestsEndMarker = RequestsEndMarker::new();

src/boot/mod.rs

@@ -0,0 +1 @@
+pub mod limine;

src/drivers/mod.rs

@@ -0,0 +1 @@
+pub mod serial;

src/drivers/serial.rs

@@ -0,0 +1,179 @@
+use crate::arch::port::{read_u8, write_u8};
+
+const COM1_BASE: u16 = 0x3F8;
+
+mod register {
+    pub const DATA_BUFFER: u16 = 0;
+
+    pub const DIVISOR_LOW: u16 = 0;
+    pub const INTERRUPT_ENABLE: u16 = 1;
+    pub const DIVISOR_HIGH: u16 = 1;
+
+    pub const INTERRUPT_IDENTIFICATION: u16 = 2;
+    pub const FIFO_CONTROL: u16 = 2;
+
+    pub const LINE_CONTROL: u16 = 3;
+    pub const MODEM_CONTROL: u16 = 4;
+    pub const LINE_STATUS: u16 = 5;
+    pub const MODEM_STATUS: u16 = 6;
+    pub const SCRATCH: u16 = 7;
+}
+
+mod fifo_control {
+    pub const ENABLE: u8 = 1 << 0;
+    pub const CLEAR_RECEIVE: u8 = 1 << 1;
+    pub const CLEAR_TRANSMIT: u8 = 1 << 2;
+    pub const TRIGGER_LEVEL_14: u8 = 0b11 << 6;
+}
+
+mod line_control {
+    pub const DATA_BITS_8: u8 = 0b11;
+    pub const DLAB: u8 = 1 << 7;
+}
+
+mod line_status {
+    pub const TRANSMITTER_EMPTY: u8 = 1 << 5;
+}
+
+mod modem_control {
+    pub const DATA_TERMINAL_READY: u8 = 1 << 0;
+    pub const REQUEST_TO_SEND: u8 = 1 << 1;
+    // commonly controls whether IRQs are enabled or disabled
+    pub const OUT_1: u8 = 1 << 2;
+    // unused in PC implementations
+    pub const OUT_2: u8 = 1 << 3;
+    pub const LOOPBACK: u8 = 1 << 4;
+}
+
+#[derive(Debug)]
+pub enum SerialPortError {
+    NotFound,
+    Faulty,
+}
+
+struct SerialPort {
+    base: u16,
+}
+
+impl SerialPort {
+    pub fn new(base: u16) -> Self {
+        Self { base }
+    }
+
+    pub fn init(&self) -> Result<(), SerialPortError> {
+        const SCRATCH_TEST_VALUE: u8 = 0x42;
+        const LOOPBACK_TEST_VALUE: u8 = 0xAE;
+
+        // The scratch register has no hardware-defined behavior, so it can be used to probe the port.
+        self.write_register(register::SCRATCH, SCRATCH_TEST_VALUE);
+        if self.read_register(register::SCRATCH) != SCRATCH_TEST_VALUE {
+            return Err(SerialPortError::NotFound);
+        }
+
+        self.write_register(register::INTERRUPT_ENABLE, 0);
+
+        // DLAB changes registers 0 and 1 into the low and high divisor registers so we can set the baud rate
+        self.write_register(register::LINE_CONTROL, line_control::DLAB);
+        // in this case we are setting the baud rate to 115200 baud
+        self.write_register(register::DIVISOR_LOW, 1);
+        self.write_register(register::DIVISOR_HIGH, 0);
+        self.write_register(register::LINE_CONTROL, line_control::DATA_BITS_8);
+
+        self.write_register(
+            register::FIFO_CONTROL,
+            fifo_control::ENABLE
+                | fifo_control::CLEAR_RECEIVE
+                | fifo_control::CLEAR_TRANSMIT
+                | fifo_control::TRIGGER_LEVEL_14,
+        );
+
+        self.write_register(
+            register::MODEM_CONTROL,
+            modem_control::DATA_TERMINAL_READY
+                | modem_control::REQUEST_TO_SEND
+                | modem_control::OUT_2,
+        );
+
+        self.write_register(
+            register::MODEM_CONTROL,
+            modem_control::REQUEST_TO_SEND
+                | modem_control::OUT_1
+                | modem_control::OUT_2
+                | modem_control::LOOPBACK,
+        );
+
+        self.write_byte(LOOPBACK_TEST_VALUE);
+        if self.read_register(register::DATA_BUFFER) != LOOPBACK_TEST_VALUE {
+            return Err(SerialPortError::Faulty);
+        }
+
+        self.write_register(
+            register::MODEM_CONTROL,
+            modem_control::DATA_TERMINAL_READY
+                | modem_control::REQUEST_TO_SEND
+                | modem_control::OUT_1
+                | modem_control::OUT_2,
+        );
+
+        Ok(())
+    }
+
+    fn write_register(&self, register: u16, value: u8) {
+        unsafe { write_u8(self.base + register, value) };
+    }
+
+    fn read_register(&self, register: u16) -> u8 {
+        unsafe { read_u8(self.base + register) }
+    }
+
+    fn can_transfer(&self) -> bool {
+        self.read_register(register::LINE_STATUS) & line_status::TRANSMITTER_EMPTY != 0
+    }
+
+    pub fn write_byte(&self, byte: u8) {
+        if byte == b'\n' {
+            self.write_byte(b'\r');
+        }
+
+        while !self.can_transfer() {
+            core::hint::spin_loop();
+        }
+
+        self.write_register(register::DATA_BUFFER, byte);
+    }
+}
+
+impl core::fmt::Write for SerialPort {
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        for byte in s.bytes() {
+            self.write_byte(byte);
+        }
+        Ok(())
+    }
+}
+
+fn com1() -> SerialPort {
+    SerialPort::new(COM1_BASE)
+}
+
+pub fn init() -> Result<(), SerialPortError> {
+    com1().init()
+}
+
+pub fn print(args: core::fmt::Arguments) {
+    use core::fmt::Write;
+
+    let mut serial = com1();
+    let _ = serial.write_fmt(args);
+}
+
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ($crate::drivers::serial::print(format_args!($($arg)*)));
+}
+
+#[macro_export]
+macro_rules! println {
+    () => ($crate::drivers::serial::print(format_args!("\n")));
+    ($($arg:tt)*) => ($crate::drivers::serial::print(format_args!("{}\n", format_args!($($arg)*))));
+}

src/main.rs

@@ -0,0 +1,66 @@
+#![feature(abi_x86_interrupt, negative_impls)]
+#![allow(clippy::needless_return)]
+#![no_std]
+#![no_main]
+
+mod arch;
+mod boot;
+mod drivers;
+
+use boot::limine::{BASE_REVISION, FRAMEBUFFER_REQUEST};
+
+use crate::drivers::serial;
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    serial::init().unwrap();
+
+    assert!(BASE_REVISION.is_supported());
+
+    draw_gradient();
+
+    hcf();
+}
+
+fn draw_gradient() {
+    if let Some(framebuffer_response) = FRAMEBUFFER_REQUEST.response() {
+        if let Some(&framebuffer) = framebuffer_response.framebuffers().first() {
+            let buffer = unsafe {
+                core::slice::from_raw_parts_mut(
+                    framebuffer.address().cast::<u32>(),
+                    framebuffer.size() / 4,
+                )
+            };
+
+            for y in 0..framebuffer.height {
+                for x in 0..framebuffer.width {
+                    let r = (255 * x) / (framebuffer.width - 1);
+                    let g = (255 * y) / (framebuffer.height - 1);
+                    let b = 255 - r;
+
+                    let pixel = ((r as u32) << 16) | ((g as u32) << 8) | (b as u32);
+                    buffer
+                        [(((y * framebuffer.pitch) / (framebuffer.bpp as u64 / 8)) + x) as usize] =
+                        pixel
+                }
+            }
+        }
+    }
+}
+
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+    hcf();
+}
+
+pub fn hcf() -> ! {
+    loop {
+        unsafe {
+            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+            core::arch::asm!("hlt");
+
+            #[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))]
+            core::arch::asm!("wfi");
+        }
+    }
+}