use virtual workspaces for heap

.cargo/config.toml

@@ -1,5 +1,2 @@
-[build]
-target = "aarch64-unknown-none"
-
 [target.aarch64-unknown-none]
 rustflags = ["-C", "link-arg=-Tlink.ld"]

.gitignore

@@ -3,3 +3,4 @@ kernel8.img
 .env
 sd.img
 settings.json
+.DS_Store

.vscode/tasks.json

@@ -14,7 +14,7 @@
     {
       "label": "Run QEMU",
       "type": "shell",
-      "command": "qemu-system-aarch64 -M raspi3b -cpu cortex-a53 -serial stdio -sd sd.img -display none -kernel ${workspaceFolder}/target/aarch64-unknown-none/debug/kernel8.img -S -s -m 1024",
+      "command": "llvm-objcopy -O binary target/aarch64-unknown-none/debug/nova target/aarch64-unknown-none/debug/kernel8.img && qemu-system-aarch64 -M raspi3b -cpu cortex-a53 -serial stdio -sd sd.img -kernel ${workspaceFolder}/target/aarch64-unknown-none/debug/kernel8.img -S -s -m 1024",
       "isBackground": true,
       "dependsOn": ["Build"]
     }

Cargo.lock

@@ -2,6 +2,17 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "NovaError"
+version = "0.1.0"
+
+[[package]]
+name = "heap"
+version = "0.1.0"
+dependencies = [
+ "NovaError",
+]
+
 [[package]]
 name = "libm"
 version = "0.2.15"
@@ -12,5 +23,7 @@ checksum = "f9fbbcab51052fe104eb5e5d351cf728d30a5be1fe14d9be8a3b097481fb97de"
 name = "nova"
 version = "0.1.0"
 dependencies = [
+ "NovaError",
+ "heap",
  "libm",
 ]

Cargo.toml

@@ -14,3 +14,11 @@ panic = "abort"
 
 [dependencies]
 libm = "0.2.15"
+heap = {path = "heap"}
+NovaError = {path = "NovaError"}
+
+[workspace]
+
+members = [ "NovaError",
+    "heap"
+]

NovaError/Cargo.toml

@@ -0,0 +1,4 @@
+[package]
+name = "NovaError"
+version = "0.1.0"
+edition = "2024"

NovaError/src/lib.rs

@@ -0,0 +1,11 @@
+#![no_std]
+
+use core::fmt::Debug;
+use core::prelude::rust_2024::derive;
+
+#[derive(Debug)]
+pub enum NovaError {
+    Mailbox,
+    HeapFull,
+    EmptyHeapSegmentNotAllowed,
+}

README.md

@@ -8,9 +8,14 @@ NovaOS is a expository project where I build a kernel from scratch for a Raspber
 
 - Delay and sleep ✓
 - UART ✓
+- Switching ELs ✓
 - GPIOs ✓
 - GPIO Interrupts ✓
 - Communicate with peripherals via mailboxes ✓
 - Frame Buffer ✓
+- Heap Memory allocation ✓
+- Multi Core
+- Dynamic clock speed
 - MMU
+- Multiprocessing
 - Basic Terminal over UART

heap/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "heap"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+NovaError = {path = "../NovaError"}

heap/src/lib.rs

@@ -0,0 +1,194 @@
+#![allow(static_mut_refs)]
+#![cfg_attr(not(test), no_std)]
+
+use core::{
+    alloc::GlobalAlloc,
+    default::Default,
+    mem::size_of,
+    prelude::v1::*,
+    ptr::{self, null_mut, read_volatile},
+    result::Result,
+};
+
+use NovaError::NovaError;
+
+#[cfg(not(target_os = "none"))]
+extern crate std;
+
+extern crate alloc;
+
+#[repr(C, align(16))]
+pub struct HeapHeader {
+    pub next: *mut HeapHeader,
+    before: *mut HeapHeader,
+    pub size: usize,
+    free: bool,
+}
+
+const HEAP_HEADER_SIZE: usize = size_of::<HeapHeader>();
+const MIN_BLOCK_SIZE: usize = 16;
+
+// TODO: This implementation has to be reevaluated when implementing multiprocessing
+// Spinlock could be a solution but has its issues:
+// https://matklad.github.io/2020/01/02/spinlocks-considered-harmful.html
+
+pub struct Heap {
+    pub start_address: *mut HeapHeader,
+    pub end_address: *mut HeapHeader,
+    pub raw_size: usize,
+}
+impl Heap {
+    pub const fn empty() -> Self {
+        Self {
+            start_address: null_mut() as *mut HeapHeader,
+            end_address: null_mut() as *mut HeapHeader,
+            raw_size: 0,
+        }
+    }
+
+    pub fn init(&mut self, heap_start: usize, heap_end: usize) {
+        self.start_address = heap_start as *mut HeapHeader;
+        self.end_address = heap_end as *mut HeapHeader;
+
+        self.raw_size = heap_end - heap_start;
+
+        unsafe {
+            ptr::write(
+                self.start_address,
+                HeapHeader {
+                    next: null_mut(),
+                    before: null_mut(),
+                    size: self.raw_size - HEAP_HEADER_SIZE,
+                    free: true,
+                },
+            );
+        }
+    }
+
+    unsafe fn find_first_fit(&self, size: usize) -> Result<*mut HeapHeader, NovaError> {
+        let mut current = self.start_address;
+        while !fits(size, current) {
+            if (*self.start_address).next.is_null() {
+                return Err(NovaError::HeapFull);
+            }
+            current = (*current).next;
+        }
+        Ok(current)
+    }
+
+    pub fn malloc(&self, mut size: usize) -> Result<*mut u8, NovaError> {
+        if size == 0 {
+            return Err(NovaError::EmptyHeapSegmentNotAllowed);
+        }
+
+        if size < MIN_BLOCK_SIZE {
+            size = MIN_BLOCK_SIZE;
+        }
+
+        // Align size to the next 16 bytes
+        size += (16 - (size % 16)) % 16;
+
+        unsafe {
+            // Find First-Fit memory segment
+            let current = self.find_first_fit(size)?;
+
+            // Return entire block WITHOUT generating a new header
+            // if the current block doesn't have enough space to hold: requested size + HEAP_HEADER_SIZE + MIN_BLOCK_SIZE
+            if (*current).size < size + HEAP_HEADER_SIZE + MIN_BLOCK_SIZE {
+                (*current).free = false;
+                return Ok(current.byte_add(HEAP_HEADER_SIZE) as *mut u8);
+            }
+
+            Self::fragment_segment(current, size);
+
+            let data_start_address = current.byte_add(HEAP_HEADER_SIZE);
+
+            Ok(data_start_address as *mut u8)
+        }
+    }
+
+    unsafe fn fragment_segment(current: *mut HeapHeader, size: usize) {
+        let byte_offset = HEAP_HEADER_SIZE + size;
+        let new_address = unsafe { current.byte_add(byte_offset) };
+
+        // Handle case where fragmenting center free space
+        let next = (*current).next;
+        if !(*current).next.is_null() {
+            (*next).before = new_address;
+        }
+
+        unsafe {
+            ptr::write(
+                new_address as *mut HeapHeader,
+                HeapHeader {
+                    next,
+                    before: current,
+                    size: (*current).size - size - HEAP_HEADER_SIZE,
+                    free: true,
+                },
+            )
+        };
+        (*current).next = new_address;
+        (*current).free = false;
+        (*current).size = size;
+    }
+
+    pub fn free(&self, pointer: *mut u8) -> Result<(), NovaError> {
+        let mut segment = unsafe { pointer.sub(HEAP_HEADER_SIZE) as *mut HeapHeader };
+        unsafe {
+            // IF prev is free:
+            // Delete header, add size to previous and fix pointers.
+            // Move Head left
+            if !(*segment).before.is_null() && (*(*segment).before).free {
+                let before_head = (*segment).before;
+                (*before_head).size += (*segment).size + HEAP_HEADER_SIZE;
+                delete_header(segment);
+                segment = before_head;
+            }
+            // IF next is free:
+            // Delete next header and merge size, fix pointers
+            if !(*segment).next.is_null() && (*(*segment).next).free {
+                let next_head = (*segment).next;
+                (*segment).size += (*next_head).size + HEAP_HEADER_SIZE;
+                delete_header(next_head);
+            }
+
+            // Neither: Set free
+            (*segment).free = true;
+        }
+
+        Ok(())
+    }
+}
+
+unsafe impl GlobalAlloc for Heap {
+    unsafe fn alloc(&self, layout: core::alloc::Layout) -> *mut u8 {
+        self.malloc(layout.size()).unwrap()
+    }
+
+    unsafe fn dealloc(&self, ptr: *mut u8, _: core::alloc::Layout) {
+        self.free(ptr).unwrap();
+    }
+}
+
+unsafe impl Sync for Heap {}
+
+unsafe fn fits(size: usize, header: *mut HeapHeader) -> bool {
+    (*header).free && size <= (*header).size
+}
+
+unsafe fn delete_header(header: *mut HeapHeader) {
+    let before = (*header).before;
+    let next = (*header).next;
+
+    if !before.is_null() {
+        (*before).next = next;
+    }
+
+    if !next.is_null() {
+        (*next).before = before;
+    }
+}
+
+#[cfg(test)]
+mod tests {}

link.ld

@@ -27,9 +27,17 @@ SECTIONS {
         KEEP(*(.vector_table))
     }
 
-    .stack 0x8018000 : ALIGN(16)
+    .heap 0x8000000 : ALIGN(16)
+    {
+    __heap_start = .;
+    . += 0x10000; #10kB
+    __heap_end = .;
+    }
+
+    .stack : ALIGN(16)
     {
     __stack_start = .;
+    . += 0x10000; #10kB stack
     __stack_end = .;
     }
 

src/framebuffer.rs

@@ -9,7 +9,6 @@ use crate::mailbox::{read_mailbox, write_mailbox};
 struct Mailbox([u32; 36]);
 
 const ALLOCATE_BUFFER: u32 = 0x0004_0001;
-const GET_PHYSICAL_DISPLAY_WH: u32 = 0x0004_0003;
 const SET_PHYSICAL_DISPLAY_WH: u32 = 0x0004_8003;
 const SET_VIRTUAL_DISPLAY_WH: u32 = 0x0004_8004;
 const SET_PIXEL_DEPTH: u32 = 0x0004_8005;
@@ -242,26 +241,3 @@ impl FrameBuffer {
         }
     }
 }
-
-pub fn print_display_resolution() {
-    let mut mailbox: [u32; 8] = [0; 8];
-    mailbox[0] = 8 * 4;
-    mailbox[1] = 0;
-    mailbox[2] = GET_PHYSICAL_DISPLAY_WH;
-    mailbox[3] = 8;
-    mailbox[4] = 0;
-    mailbox[5] = 0;
-    mailbox[6] = 0;
-    mailbox[7] = 0;
-
-    let addr = core::ptr::addr_of!(mailbox[0]) as u32;
-
-    write_mailbox(8, addr);
-
-    let _ = read_mailbox(8);
-    if mailbox[1] == 0 {
-        println!("Failed");
-    }
-
-    println!("Width x Height: {}x{}", mailbox[5], mailbox[6]);
-}

src/lib.rs

@@ -1,6 +1,33 @@
 #![no_std]
 
-use core::ptr::{read_volatile, write_volatile};
+use core::{
+    panic::PanicInfo,
+    ptr::{read_volatile, write_volatile},
+};
+
+use heap::Heap;
+
+unsafe extern "C" {
+    unsafe static mut __heap_start: u8;
+    unsafe static mut __heap_end: u8;
+}
+
+#[global_allocator]
+pub static mut GLOBAL_ALLOCATOR: Heap = Heap::empty();
+
+pub unsafe fn init_heap() {
+    let start = core::ptr::addr_of_mut!(__heap_start) as usize;
+    let end = core::ptr::addr_of_mut!(__heap_end) as usize;
+
+    GLOBAL_ALLOCATOR.init(start, end);
+}
+
+#[panic_handler]
+fn panic(_panic: &PanicInfo) -> ! {
+    loop {
+        println!("Panic");
+    }
+}
 
 #[macro_export]
 macro_rules! print {
@@ -25,7 +52,6 @@ pub mod configuration;
 pub mod framebuffer;
 pub mod irq_interrupt;
 pub mod mailbox;
-pub mod math;
 pub mod timer;
 
 pub fn mmio_read(address: u32) -> u32 {
@@ -35,8 +61,3 @@ pub fn mmio_read(address: u32) -> u32 {
 pub fn mmio_write(address: u32, data: u32) {
     unsafe { write_volatile(address as *mut u32, data) }
 }
-
-#[derive(Debug)]
-pub enum NovaError {
-    Mailbox,
-}

src/mailbox.rs

@@ -1,4 +1,4 @@
-use crate::{mmio_read, mmio_write, NovaError};
+use crate::{mmio_read, mmio_write};
 
 const MBOX_BASE: u32 = 0x3F00_0000 + 0xB880;
 
@@ -29,7 +29,7 @@ macro_rules! mailbox_command {
         /// More information at: https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
         pub fn $name(
             request_data: [u32; $request_len / 4],
-        ) -> Result<[u32; $response_len / 4], NovaError> {
+        ) -> Result<[u32; $response_len / 4], NovaError::NovaError> {
             let mut mailbox =
                 [0u32; (HEADER_LENGTH + max!($request_len, $response_len) + FOOTER_LENGTH) / 4];
             mailbox[0] = (HEADER_LENGTH + max!($request_len, $response_len) + FOOTER_LENGTH) as u32; // Total length in Bytes
@@ -48,17 +48,20 @@ macro_rules! mailbox_command {
             let _ = read_mailbox(8);
 
             if mailbox[1] == 0 {
-                return Err(NovaError::Mailbox);
+                return Err(NovaError::NovaError::Mailbox);
             }
 
-            let mut out = [0u32; $response_len / 4]; // TODO: Can this be improved?
+            let mut out = [0u32; $response_len / 4];
             out.copy_from_slice(&mailbox[5..(5 + $response_len / 4)]);
             Ok(out)
         }
     };
 }
 
-mailbox_command!(mb_read_soc_temp, 0x00030006, 4, 8);
+mailbox_command!(mb_read_soc_temp, 0x0003_0006, 4, 8);
+
+// Framebuffer
+mailbox_command!(mb_get_display_resolution, 0x0004_0003, 0, 8);
 
 pub fn read_mailbox(channel: u32) -> u32 {
     // Wait until mailbox is not empty

src/main.rs

@@ -1,18 +1,19 @@
 #![no_main]
 #![no_std]
 #![feature(asm_experimental_arch)]
-
+#![allow(static_mut_refs)]
 use core::{
     arch::{asm, global_asm},
-    panic::PanicInfo,
     ptr::write_volatile,
 };
 
+extern crate alloc;
+
 use nova::{
-    framebuffer::{print_display_resolution, FrameBuffer, BLUE, GREEN, ORANGE, RED, YELLOW},
+    framebuffer::{FrameBuffer, BLUE, GREEN, RED},
+    init_heap,
     irq_interrupt::enable_irq_source,
     mailbox::mb_read_soc_temp,
-    math::polar_to_cartesian,
     peripherals::{
         gpio::{
             blink_gpio, gpio_pull_up, set_falling_edge_detect, set_gpio_function, GPIOFunction,
@@ -22,6 +23,7 @@ use nova::{
     },
     print, println,
     timer::{delay_nops, sleep_us},
+    GLOBAL_ALLOCATOR,
 };
 
 global_asm!(include_str!("vector.S"));
@@ -32,19 +34,12 @@ extern "C" {
     static mut __bss_end: u32;
 }
 
-#[panic_handler]
-fn panic(_panic: &PanicInfo) -> ! {
-    loop {
-        println!("Panic");
-    }
-}
-
 #[no_mangle]
-#[link_section = ".text._start"]
+#[cfg_attr(not(test), link_section = ".text._start")]
 pub unsafe extern "C" fn _start() {
     // Set the stack pointer
     asm!(
-        "ldr x0, =0x8008000",
+        "ldr x0, =__stack_end",
         "mov sp, x0",
         "b main",
         options(noreturn)
@@ -61,8 +56,6 @@ pub extern "C" fn main() -> ! {
     // Set ACT Led to Outout
     let _ = set_gpio_function(21, GPIOFunction::Output);
 
-    print_current_el_str();
-
     // Delay so clock speed can stabilize
     delay_nops(50000);
     println!("Hello World!");
@@ -86,7 +79,12 @@ unsafe fn zero_bss() {
 
 #[no_mangle]
 pub extern "C" fn kernel_main() -> ! {
-    print_current_el_str();
+    println!("EL: {}", get_current_el());
+
+    unsafe {
+        init_heap();
+        heap_test();
+    };
 
     sleep_us(500_000);
 
@@ -96,20 +94,7 @@ pub extern "C" fn kernel_main() -> ! {
     gpio_pull_up(26);
     set_falling_edge_detect(26, true);
 
-    print_display_resolution();
     let fb = FrameBuffer::new();
-    print_display_resolution();
-
-    for a in 0..360 {
-        let (x, y) = polar_to_cartesian(100.0, a as f32);
-        fb.draw_line(
-            150,
-            150,
-            (150.0 + x) as u32,
-            (150.0 + y) as u32,
-            a * (0x00FFFFFF / 360),
-        );
-    }
 
     fb.draw_square(500, 500, 600, 700, RED);
     fb.draw_square_fill(800, 800, 900, 900, GREEN);
@@ -118,10 +103,6 @@ pub extern "C" fn kernel_main() -> ! {
     fb.draw_string("Hello World! :D\nTest next Line", 500, 5, 3, BLUE);
 
     fb.draw_function(cos, 100, 101, RED);
-    fb.draw_function(cos, 100, 102, ORANGE);
-    fb.draw_function(cos, 100, 103, YELLOW);
-    fb.draw_function(cos, 100, 104, GREEN);
-    fb.draw_function(cos, 100, 105, BLUE);
 
     loop {
         let temp = mb_read_soc_temp([0]).unwrap();
@@ -131,11 +112,21 @@ pub extern "C" fn kernel_main() -> ! {
     }
 }
 
+unsafe fn heap_test() {
+    let a = GLOBAL_ALLOCATOR.malloc(32).unwrap();
+    let b = GLOBAL_ALLOCATOR.malloc(64).unwrap();
+    let c = GLOBAL_ALLOCATOR.malloc(128).unwrap();
+    let _ = GLOBAL_ALLOCATOR.malloc(256).unwrap();
+    GLOBAL_ALLOCATOR.free(b).unwrap();
+    GLOBAL_ALLOCATOR.free(a).unwrap();
+    GLOBAL_ALLOCATOR.free(c).unwrap();
+}
+
 fn cos(x: u32) -> f64 {
     libm::cos(x as f64 * 0.1) * 20.0
 }
 
-pub fn get_current_el() -> u64 {
+fn get_current_el() -> u64 {
     let el: u64;
     unsafe {
         asm!(
@@ -153,16 +144,3 @@ fn enable_uart() {
     let _ = set_gpio_function(14, GPIOFunction::Alternative0);
     let _ = set_gpio_function(15, GPIOFunction::Alternative0);
 }
-
-fn print_current_el_str() {
-    let el = get_current_el();
-    let el_str = match el {
-        0b11 => "Level 3",
-        0b10 => "Level 2",
-        0b01 => "Level 1",
-        0b00 => "Level 0",
-        _ => "Unknown EL",
-    };
-
-    println!("{}", el_str);
-}

src/math.rs

@@ -1,5 +0,0 @@
-pub fn polar_to_cartesian(r: f32, theta_rad: f32) -> (f32, f32) {
-    let x = r * libm::cosf(theta_rad);
-    let y = r * libm::sinf(theta_rad);
-    (x, y)
-}

src/peripherals/gpio.rs

@@ -170,7 +170,7 @@ pub fn set_rising_edge_detect(gpio: u8, enable: bool) {
     mmio_write(register_addr, new_val);
 }
 
-pub fn blink_gpio(gpio: u8, duration_ms: u32) {
+pub fn blink_gpio(gpio: u8, duration_ms: u64) {
     let _ = gpio_high(gpio);
 
     sleep_ms(duration_ms);

src/timer.rs

@@ -1,32 +1,61 @@
-use crate::mmio_read;
+use core::{hint::spin_loop, ptr::read_volatile};
 
-const TIMER_CLO: u32 = 0x3F00_3004;
+const TIMER_CLOCK_LO: u32 = 0x3F00_3004;
+const TIMER_CLOCK_HI: u32 = 0x3F00_3008;
 
-fn read_clo() -> u32 {
+fn read_timer_32() -> u32 {
-    mmio_read(TIMER_CLO)
+    unsafe { read_volatile(TIMER_CLOCK_LO as *const u32) }
+}
+
+fn read_timer_64() -> u64 {
+    loop {
+        let clock_hi1 = unsafe { read_volatile(TIMER_CLOCK_HI as *const u32) };
+        let clock_lo = unsafe { read_volatile(TIMER_CLOCK_LO as *const u32) };
+        let clock_hi2 = unsafe { read_volatile(TIMER_CLOCK_HI as *const u32) };
+
+        // account for roll over during read
+        if clock_hi1 == clock_hi2 {
+            return ((clock_hi1 as u64) << 32) | clock_lo as u64;
+        }
+    }
 }
 
 /// Sleep for `us` microseconds
-pub fn sleep_us(us: u32) {
+pub fn sleep_us(us: u64) {
-    let start = read_clo();
+    if us < u32::MAX as u64 {
-    while read_clo() - start < us {
+        sleep_us_u32(us as u32);
-        unsafe { core::arch::asm!("nop") }
+    } else {
+        sleep_us_u64(us);
+    }
+}
+
+fn sleep_us_u32(us: u32) {
+    let start = read_timer_32();
+    while read_timer_32().wrapping_sub(start) < us {
+        spin_loop();
+    }
+}
+
+fn sleep_us_u64(us: u64) {
+    let start = read_timer_64();
+    while read_timer_64().wrapping_sub(start) < us {
+        spin_loop();
     }
 }
 
 /// Sleep for `ms` milliseconds
-pub fn sleep_ms(ms: u32) {
+pub fn sleep_ms(ms: u64) {
-    sleep_us(ms * 1000);
+    sleep_us(ms * 1_000);
 }
 
 /// Sleep for `s` seconds
-pub fn sleep_s(s: u32) {
+pub fn sleep_s(s: u64) {
-    sleep_us(s * 1000);
+    sleep_ms(s * 1_000);
 }
 
 /// Wait for `count` operations to pass
 pub fn delay_nops(count: u32) {
     for _ in 0..count {
-        unsafe { core::arch::asm!("nop") }
+        spin_loop()
     }
 }