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"]

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,
+}

heap/Cargo.toml

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

heap/src/lib.rs

@@ -1,17 +1,21 @@
 #![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 crate::NovaError;
-extern crate alloc;
+use NovaError::NovaError;
 
-extern "C" {
-    static mut __heap_start: u8;
-    static mut __heap_end: u8;
-}
+#[cfg(not(target_os = "none"))]
+extern crate std;
+
+extern crate alloc;
 
 #[repr(C, align(16))]
 pub struct HeapHeader {
@@ -27,51 +31,26 @@ 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 static mut HEAP: Heap = Heap {
-    start_address: &raw mut __heap_start as *mut HeapHeader,
-    end_address: &raw mut __heap_end as *mut HeapHeader,
-    raw_size: 0,
-};
-
-// TODO: investigate if there is a better alternative to this
-pub unsafe fn init_global_heap() {
-    HEAP.init();
-}
-
-#[derive(Default)]
-pub struct Novalloc;
-
-unsafe impl GlobalAlloc for Novalloc {
-    unsafe fn alloc(&self, layout: core::alloc::Layout) -> *mut u8 {
-        HEAP.malloc(layout.size()).unwrap()
-    }
-
-    unsafe fn dealloc(&self, ptr: *mut u8, _: core::alloc::Layout) {
-        HEAP.free(ptr).unwrap();
-    }
-}
-
-#[global_allocator]
-static GLOBAL_ALLOCATOR: Novalloc = Novalloc;
 
 pub struct Heap {
-    start_address: *mut HeapHeader,
-    end_address: *mut HeapHeader,
-    raw_size: usize,
+    pub start_address: *mut HeapHeader,
+    pub end_address: *mut HeapHeader,
+    pub raw_size: usize,
 }
 impl Heap {
-    pub fn new(heap_start: usize, heap_end: usize) -> Self {
-        let mut instance = Self {
-            start_address: &raw const heap_start as *mut HeapHeader,
-            end_address: &raw const heap_end as *mut HeapHeader,
-            raw_size: heap_end - heap_start,
-        };
-        instance.init();
-        instance
+    pub const fn empty() -> Self {
+        Self {
+            start_address: null_mut() as *mut HeapHeader,
+            end_address: null_mut() as *mut HeapHeader,
+            raw_size: 0,
+        }
     }
 
-    fn init(&mut self) {
-        self.raw_size = self.end_address as usize - self.start_address as usize;
+    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(
@@ -130,7 +109,7 @@ impl Heap {
 
     unsafe fn fragment_segment(current: *mut HeapHeader, size: usize) {
         let byte_offset = HEAP_HEADER_SIZE + size;
-        let new_address = current.byte_add(byte_offset);
+        let new_address = unsafe { current.byte_add(byte_offset) };
 
         // Handle case where fragmenting center free space
         let next = (*current).next;
@@ -138,15 +117,17 @@ impl Heap {
             (*next).before = new_address;
         }
 
-        ptr::write(
-            new_address as *mut HeapHeader,
-            HeapHeader {
-                next,
-                before: current,
-                size: (*current).size - size - HEAP_HEADER_SIZE,
-                free: true,
-            },
-        );
+        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;
@@ -178,26 +159,20 @@ impl Heap {
 
         Ok(())
     }
+}
 
-    pub fn traverse_heap(&self) {
-        let mut pointer_address = self.start_address;
-        loop {
-            let head = unsafe { read_volatile(pointer_address) };
-            println!("Header {:#x}", pointer_address as u32);
-            println!("free: {}", head.free);
-            println!("size: {}", head.size);
-            println!("hasNext: {}", !head.next.is_null());
-            println!("");
-            if !head.next.is_null() {
-                pointer_address = head.next;
-            } else {
-                println!("---------------");
-                return;
-            }
-        }
+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
 }
@@ -214,3 +189,6 @@ unsafe fn delete_header(header: *mut HeapHeader) {
         (*next).before = before;
     }
 }
+
+#[cfg(test)]
+mod tests {}

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 {
@@ -23,7 +50,6 @@ pub mod peripherals;
 
 pub mod configuration;
 pub mod framebuffer;
-pub mod heap;
 pub mod irq_interrupt;
 pub mod mailbox;
 pub mod timer;
@@ -35,10 +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,
-    HeapFull,
-    EmptyHeapSegmentNotAllowed,
-}

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
@@ -48,7 +48,7 @@ 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];

src/main.rs

@@ -4,7 +4,6 @@
 #![allow(static_mut_refs)]
 use core::{
     arch::{asm, global_asm},
-    panic::PanicInfo,
     ptr::write_volatile,
 };
 
@@ -12,7 +11,7 @@ extern crate alloc;
 
 use nova::{
     framebuffer::{FrameBuffer, BLUE, GREEN, RED},
-    heap::{init_global_heap, HEAP},
+    init_heap,
     irq_interrupt::enable_irq_source,
     mailbox::mb_read_soc_temp,
     peripherals::{
@@ -24,6 +23,7 @@ use nova::{
     },
     print, println,
     timer::{delay_nops, sleep_us},
+    GLOBAL_ALLOCATOR,
 };
 
 global_asm!(include_str!("vector.S"));
@@ -34,15 +34,8 @@ 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!(
@@ -88,7 +81,10 @@ unsafe fn zero_bss() {
 pub extern "C" fn kernel_main() -> ! {
     println!("EL: {}", get_current_el());
 
-    heap_test();
+    unsafe {
+        init_heap();
+        heap_test();
+    };
 
     sleep_us(500_000);
 
@@ -116,21 +112,14 @@ pub extern "C" fn kernel_main() -> ! {
     }
 }
 
-fn heap_test() {
-    unsafe {
-        init_global_heap();
-        let a = HEAP.malloc(32).unwrap();
-        let b = HEAP.malloc(64).unwrap();
-        let c = HEAP.malloc(128).unwrap();
-        let _ = HEAP.malloc(256).unwrap();
-        HEAP.traverse_heap();
-        HEAP.free(b).unwrap();
-        HEAP.traverse_heap();
-        HEAP.free(a).unwrap();
-        HEAP.traverse_heap();
-        HEAP.free(c).unwrap();
-        HEAP.traverse_heap();
-    }
+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 {