feat: Application manager (#8)

* feat: map text area to kernel memory space, first application_manager
implementation

* feat: start application via application_manager

* feat: terminal, start app by ID

* feat: support CLI args, by applying System V ABI concepts

* refactor: rename terminal to console. Minor cleanup

* docs: README.md

.gitignore

@@ -5,3 +5,9 @@ sd.img
 settings.json
 .DS_Store
 .venv
+.nvimlog
+__pycache__
+.pytest_cache
+
+build/
+

.vscode/launch.json

@@ -3,7 +3,7 @@
   "compounds": [
     {
       "name": "Run QEMU + Attach LLDB",
-      "configurations": ["Attach LLDB"],
+      "configurations": ["LLDB"],
       "preLaunchTask": "Run QEMU"
     }
   ],
@@ -33,13 +33,47 @@
       ],
       "preLaunchTask": "Run QEMU"
     },
-
     {
-      "name": "Attach LLDB",
+      "name": "Attach to QEMU (AArch64) wo. window",
+      "type": "cppdbg",
+      "request": "launch",
+      "program": "${workspaceFolder}/target/aarch64-unknown-none/debug/nova",
+      "miDebuggerServerAddress": "localhost:1234",
+      "miDebuggerPath": "gdb",
+      "cwd": "${workspaceFolder}",
+      "stopAtEntry": true,
+      "externalConsole": false,
+      "MIMode": "gdb",
+      "setupCommands": [
+        {
+          "description": "Enable pretty-printing for gdb",
+          "text": "-enable-pretty-printing",
+          "ignoreFailures": true
+        },
+        {
+          "description": "Show assembly on stop",
+          "text": "set disassemble-next-line on",
+          "ignoreFailures": true
+        }
+      ],
+      "preLaunchTask": "Run QEMU wo window"
+    },
+    {
+      "name": "LLDB",
       "type": "lldb",
       "request": "attach",
-      "debugServer": 1234,
       "program": "${workspaceFolder}/target/aarch64-unknown-none/debug/nova",
+      "preLaunchTask": "Run QEMU",
+      "stopOnEntry": true,
+      "processCreateCommands": ["gdb-remote localhost:1234"]
+    },
+
+    {
+      "name": "NVIM LLDB",
+      "type": "codelldb",
+      "request": "attach",
+      "program": "${workspaceFolder}/target/aarch64-unknown-none/debug/nova",
+      "preLaunchTask": "Run QEMU",
       "stopOnEntry": true,
       "processCreateCommands": ["gdb-remote localhost:1234"]
     }

.vscode/tasks.json

@@ -14,9 +14,38 @@
     {
       "label": "Run QEMU",
       "type": "shell",
-      "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",
+      "command": "llvm-objcopy -O binary target/aarch64-unknown-none/debug/nova target/aarch64-unknown-none/debug/kernel8.img && echo Starting QEMU&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"]
+      "dependsOn": ["Build"],
+      "problemMatcher": {
+                "pattern": {
+                    "regexp": "^(Starting QEMU)",
+                    "line": 1,
+                },
+                "background": {
+                    "activeOnStart": true,
+                    "beginsPattern": "^(Starting QEMU)",
+                    "endsPattern": "^(Starting QEMU)"
+                }
+            }
+    },
+        {
+      "label": "Run QEMU wo window",
+      "type": "shell",
+      "command": "llvm-objcopy -O binary target/aarch64-unknown-none/debug/nova target/aarch64-unknown-none/debug/kernel8.img && echo Starting QEMU&qemu-system-aarch64 -M raspi3b -cpu cortex-a53 -display none -serial stdio -sd sd.img -kernel ${workspaceFolder}/target/aarch64-unknown-none/debug/kernel8.img -S -s -m 1024",
+      "isBackground": true,
+      "dependsOn": ["Build"],
+      "problemMatcher": {
+                "pattern": {
+                    "regexp": "^(Starting QEMU)",
+                    "line": 1,
+                },
+                "background": {
+                    "activeOnStart": true,
+                    "beginsPattern": "^(Starting QEMU)",
+                    "endsPattern": "^(Starting QEMU)"
+                }
+            }
     }
   ]
 }

Cargo.lock

@@ -40,14 +40,31 @@ version = "0.2.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f9fbbcab51052fe104eb5e5d351cf728d30a5be1fe14d9be8a3b097481fb97de"
 
+[[package]]
+name = "lock_api"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "224399e74b87b5f3557511d98dff8b14089b3dadafcab6bb93eab67d3aace965"
+dependencies = [
+ "scopeguard",
+]
+
+[[package]]
+name = "log"
+version = "0.4.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
+
 [[package]]
 name = "nova"
 version = "0.1.0"
 dependencies = [
  "heap",
  "libm",
+ "log",
  "nova_error",
  "paste",
+ "spin",
 ]
 
 [[package]]
@@ -122,6 +139,21 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
+
+[[package]]
+name = "spin"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d5fe4ccb98d9c292d56fec89a5e07da7fc4cf0dc11e156b41793132775d3e591"
+dependencies = [
+ "lock_api",
+]
+
 [[package]]
 name = "syn"
 version = "2.0.111"

Cargo.toml

@@ -17,6 +17,8 @@ libm = "0.2.15"
 heap = {path = "workspace/heap"}
 nova_error = {path = "workspace/nova_error"}
 paste = "1.0.15"
+log = "0.4.29"
+spin = "0.10.0"
 
 [workspace]
 

README.md

@@ -2,8 +2,6 @@
 
 NovaOS is a expository project where I build a kernel from scratch for a Raspberry PI 3 B+.
 
-[Technical write-up](https://leafnova.net/projects/pi3_kernel/)
-
 ## Features
 
 - Delay and sleep ✓
@@ -14,8 +12,11 @@ NovaOS is a expository project where I build a kernel from scratch for a Raspber
 - Communicate with peripherals via mailboxes ✓
 - Frame Buffer ✓
 - Heap Memory allocation ✓
+- MMU ✓
+- SVC instructions ~
+- Basic Console over UART ~
+- Multi Applications ~
 - Multi Core
 - Dynamic clock speed
-- MMU
+- Kernel Independent Applications
 - Multiprocessing
-- Basic Terminal over UART

link.ld

@@ -5,51 +5,42 @@ SECTIONS {
         KEEP(*(.text._start))
         *(.text .text.*)
     }
+    .vector_table ALIGN(2K) : {
+        KEEP(*(.vector_t))
+    }
+
+    . = ALIGN(4K);
+    __text_end = .;
 
     .rodata : {
         *(.rodata .rodata.*)
     }
 
     .data  : {
-        _data = .;
         *(.data .data.*)
     }
 
-    .bss (NOLOAD) : {
+    .bss ALIGN(16) (NOLOAD) : {
-        . = ALIGN(16);
         __bss_start = .;
         *(.bss .bss.*)
-        *(COMMON)
         __bss_end = .;
     }
 
-    .vector_table ALIGN(2048) : {
+    . = ALIGN(2M);
-        KEEP(*(.vector_table))
-    }
 
-    .heap : ALIGN(16)
+    __share_end = .;
-    {
-    __heap_start = .;
-    . += 0x10000; #10kB
-    __heap_end = .;
-    }
 
-    .stack : ALIGN(16)
+    # EL2 Stack
-    {
+    .stack ALIGN(16): {
     __stack_start = .;
-    . += 0x10000; #10kB stack
+    . += 100K; #100kB stack
+    . = ALIGN(16);
     __stack_end = .;
     }
 
-    .stack_el0 : ALIGN(16)
+    . = ALIGN(2M);
-    {
-    __stack_start_el0 = .;
-    . += 0x10000; #10kB stack
-    __stack_end_el0 = .;
-    }
 
-
+    __kernel_end = .;
-    _end = .;
 }
 
 __bss_size = (__bss_end - __bss_start) >> 3;

src/aarch64/mmu.rs

@@ -1,17 +1,439 @@
-use core::arch::asm;
+use core::mem::size_of;
+use nova_error::NovaError;
 
-pub fn init_mmu() {
+use crate::{
-    let ips = 0b000 << 32;
+    aarch64::mmu::physical_mapping::{
+        reserve_block, reserve_block_explicit, reserve_page, reserve_page_explicit,
+    },
+    get_current_el,
+};
 
-    // 4KB granularity
+const BLOCK: u64 = 0b01;
-    let tg0 = 0b00 << 14;
+const TABLE: u64 = 0b11;
-    let tg1 = 0b00 << 30;
+const PAGE: u64 = 0b11;
 
-    //64-25 = 29 bits of VA
+/// Allow EL0 to access this section
-    // FFFF_FF80_0000_0000 start address
+pub const EL0_ACCESSIBLE: u64 = 1 << 6;
-    let t0sz = 25;
 
-    let tcr_el1: u64 = ips | tg0 | tg1 | t0sz;
+/// Allow a page or block to be written.
+pub const WRITABLE: u64 = 0 << 7;
+/// Disallow a page or block to be written.
+pub const READ_ONLY: u64 = 1 << 7;
 
-    unsafe { asm!("msr TCR_EL1, {0:x}", in(reg) tcr_el1) };
+const ACCESS_FLAG: u64 = 1 << 10;
+const INNER_SHAREABILITY: u64 = 0b11 << 8;
+
+pub const NORMAL_MEM: u64 = 0 << 2;
+pub const DEVICE_MEM: u64 = 1 << 2;
+
+/// Disallow EL1 Execution.
+pub const PXN: u64 = 1 << 53;
+
+/// Disallow EL0 Execution.
+pub const UXN: u64 = 1 << 54;
+
+pub const GRANULARITY: usize = 4 * 1024;
+const TABLE_ENTRY_COUNT: usize = GRANULARITY / size_of::<u64>(); // 2MiB
+
+pub const LEVEL1_BLOCK_SIZE: usize = TABLE_ENTRY_COUNT * TABLE_ENTRY_COUNT * GRANULARITY;
+pub const LEVEL2_BLOCK_SIZE: usize = TABLE_ENTRY_COUNT * GRANULARITY;
+
+const L2_BLOCK_BITMAP_WORDS: usize = LEVEL2_BLOCK_SIZE / (64 * GRANULARITY);
+
+const MAX_PAGE_COUNT: usize = 1024 * 1024 * 1024 / GRANULARITY;
+
+const TRANSLATION_TABLE_BASE_ADDR: usize = 0xFFFF_FF82_0000_0000;
+#[no_mangle]
+pub static KERNEL_VIRTUAL_MEM_SPACE: usize = 0xFFFF_FF80_0000_0000;
+
+pub const STACK_START_ADDR: usize = !KERNEL_VIRTUAL_MEM_SPACE & (!0xF);
+
+pub mod physical_mapping;
+
+pub type VirtAddr = usize;
+pub type PhysAddr = usize;
+
+#[derive(Clone, Copy)]
+pub struct TableEntry {
+    value: u64,
+}
+
+impl TableEntry {
+    pub fn invalid() -> Self {
+        Self { value: 0 }
+    }
+
+    fn table_descriptor(addr: PhysAddr) -> Self {
+        Self {
+            value: (addr as u64 & 0x0000_FFFF_FFFF_F000) | TABLE,
+        }
+    }
+
+    fn block_descriptor(physical_address: usize, additional_flags: u64) -> Self {
+        Self {
+            value: (physical_address as u64 & 0x0000_FFFF_FFFF_F000)
+                | BLOCK
+                | ACCESS_FLAG
+                | INNER_SHAREABILITY
+                | additional_flags,
+        }
+    }
+
+    fn page_descriptor(physical_address: usize, additional_flags: u64) -> Self {
+        Self {
+            value: (physical_address as u64 & 0x0000_FFFF_FFFF_F000)
+                | PAGE
+                | ACCESS_FLAG
+                | INNER_SHAREABILITY
+                | additional_flags,
+        }
+    }
+
+    fn is_invalid(self) -> bool {
+        self.value & 0b11 == 0
+    }
+
+    #[inline]
+    fn address(self) -> PhysAddr {
+        self.value as usize & 0x0000_FFFF_FFFF_F000
+    }
+}
+
+pub enum PhysSource {
+    Any,
+    Explicit(PhysAddr),
+}
+
+#[repr(align(4096))]
+pub struct PageTable(pub [TableEntry; TABLE_ENTRY_COUNT]);
+
+impl Iterator for PageTable {
+    type Item = VirtAddr;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        for (offset, entity) in self.0.iter().enumerate() {
+            if entity.is_invalid() {
+                return Some(offset);
+            }
+        }
+        None
+    }
+}
+#[no_mangle]
+pub static mut TRANSLATIONTABLE_TTBR0: PageTable = PageTable([TableEntry { value: 0 }; 512]);
+#[no_mangle]
+pub static mut TRANSLATIONTABLE_TTBR1: PageTable = PageTable([TableEntry { value: 0 }; 512]);
+
+/// Allocate a memory block of `size` starting at `virtual_address`.
+pub fn allocate_memory(
+    virtual_address: usize,
+    size_bytes: usize,
+    phys: PhysSource,
+    flags: u64,
+) -> Result<(), NovaError> {
+    if !virtual_address.is_multiple_of(GRANULARITY) {
+        return Err(NovaError::Misalignment);
+    }
+    if !size_bytes.is_multiple_of(GRANULARITY) {
+        return Err(NovaError::InvalidGranularity);
+    }
+
+    let base_table = if virtual_address & KERNEL_VIRTUAL_MEM_SPACE > 0 {
+        core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1)
+    } else {
+        core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0)
+    };
+
+    match phys {
+        PhysSource::Any => map_range_dynamic(virtual_address, size_bytes, base_table, flags),
+        PhysSource::Explicit(phys_addr) => {
+            map_range_explicit(virtual_address, phys_addr, size_bytes, base_table, flags)
+        }
+    }
+}
+
+fn map_range_explicit(
+    mut virt: VirtAddr,
+    mut phys: PhysAddr,
+    size_bytes: usize,
+    base: *mut PageTable,
+    flags: u64,
+) -> Result<(), NovaError> {
+    let mut remaining = size_bytes;
+
+    while !virt.is_multiple_of(LEVEL2_BLOCK_SIZE) && remaining > 0 {
+        map_page(virt, phys, base, flags)?;
+        (virt, _) = virt.overflowing_add(GRANULARITY);
+        phys += GRANULARITY;
+        remaining -= GRANULARITY;
+    }
+
+    while remaining >= LEVEL2_BLOCK_SIZE {
+        map_l2_block(virt, phys, base, flags)?;
+        (virt, _) = virt.overflowing_add(LEVEL2_BLOCK_SIZE);
+        phys += LEVEL2_BLOCK_SIZE;
+        remaining -= LEVEL2_BLOCK_SIZE;
+    }
+
+    while remaining > 0 {
+        map_page(virt, phys, base, flags)?;
+        (virt, _) = virt.overflowing_add(GRANULARITY);
+        phys += GRANULARITY;
+        remaining -= GRANULARITY;
+    }
+
+    Ok(())
+}
+
+fn map_range_dynamic(
+    mut virt: PhysAddr,
+    size_bytes: usize,
+    base: *mut PageTable,
+    flags: u64,
+) -> Result<(), NovaError> {
+    let mut remaining = size_bytes;
+
+    while remaining >= LEVEL2_BLOCK_SIZE {
+        map_l2_block(virt, reserve_block(), base, flags)?;
+        (virt, _) = virt.overflowing_add(LEVEL2_BLOCK_SIZE);
+        remaining -= LEVEL2_BLOCK_SIZE;
+    }
+
+    while remaining > 0 {
+        map_page(virt, reserve_page(), base, flags)?;
+        (virt, _) = virt.overflowing_add(GRANULARITY);
+        remaining -= GRANULARITY;
+    }
+    Ok(())
+}
+
+/// Allocate a singe page.
+pub fn alloc_page(
+    virtual_address: VirtAddr,
+    base_table: *mut PageTable,
+    additional_flags: u64,
+) -> Result<(), NovaError> {
+    map_page(
+        virtual_address,
+        reserve_page(),
+        base_table,
+        additional_flags,
+    )
+}
+
+/// Allocate a singe page in one block.
+pub fn find_free_kerne_page_in_block(start: VirtAddr) -> Result<VirtAddr, NovaError> {
+    if !start.is_multiple_of(LEVEL2_BLOCK_SIZE) {
+        return Err(NovaError::Misalignment);
+    }
+
+    let (off1, off2, _) = virtual_address_to_table_offset(start);
+    let offsets = [off1, off2];
+    let table = unsafe {
+        &mut *navigate_table(
+            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1),
+            &offsets,
+            true,
+        )?
+    };
+
+    if let Some(offset) = table.next() {
+        return Ok(start + (offset * GRANULARITY));
+    }
+    Err(NovaError::OutOfMeomory)
+}
+
+/// Allocate a single page at an explicit `physical_address`.
+pub fn alloc_page_explicit(
+    virtual_address: usize,
+    physical_address: usize,
+    base_table: *mut PageTable,
+    additional_flags: u64,
+) -> Result<(), NovaError> {
+    reserve_page_explicit(physical_address)?;
+    map_page(
+        virtual_address,
+        physical_address,
+        base_table,
+        additional_flags,
+    )
+}
+
+pub fn map_page(
+    virtual_address: usize,
+    physical_address: usize,
+    base_table_ptr: *mut PageTable,
+    additional_flags: u64,
+) -> Result<(), NovaError> {
+    let (l1_off, l2_off, l3_off) = virtual_address_to_table_offset(virtual_address);
+
+    let offsets = [l1_off, l2_off];
+
+    let table_ptr = navigate_table(base_table_ptr, &offsets, true)?;
+    let table = unsafe { &mut *table_ptr };
+
+    if !table.0[l3_off].is_invalid() {
+        return Err(NovaError::Paging("Page already occupied."));
+    }
+
+    table.0[l3_off] = TableEntry::page_descriptor(physical_address, additional_flags);
+
+    Ok(())
+}
+
+// Allocate a level 2 block, at a explicit `physical_address`.
+pub fn alloc_block_l2_explicit(
+    virtual_addr: usize,
+    physical_address: usize,
+    base_table_ptr: *mut PageTable,
+    additional_flags: u64,
+) -> Result<(), NovaError> {
+    if !physical_address.is_multiple_of(LEVEL2_BLOCK_SIZE) {
+        return Err(NovaError::Misalignment);
+    }
+
+    reserve_block_explicit(physical_address)?;
+    map_l2_block(
+        virtual_addr,
+        physical_address,
+        base_table_ptr,
+        additional_flags,
+    )
+}
+
+pub fn map_l2_block(
+    virtual_addr: usize,
+    physical_address: usize,
+    base_table_ptr: *mut PageTable,
+    additional_flags: u64,
+) -> Result<(), NovaError> {
+    let (l1_off, l2_off, _) = virtual_address_to_table_offset(virtual_addr);
+    let offsets = [l1_off];
+    let table_ptr = navigate_table(base_table_ptr, &offsets, true)?;
+
+    let table = unsafe { &mut *table_ptr };
+
+    // Verify virtual address is available.
+    if !table.0[l2_off].is_invalid() {
+        return Err(NovaError::Paging("Block already occupied."));
+    }
+
+    let new_entry = TableEntry::block_descriptor(physical_address, additional_flags);
+
+    table.0[l2_off] = new_entry;
+
+    Ok(())
+}
+
+pub fn reserve_range(
+    start_physical_address: PhysAddr,
+    end_physical_address: PhysAddr,
+) -> Result<PhysAddr, NovaError> {
+    let mut size = end_physical_address - start_physical_address;
+    let l1_blocks = size / LEVEL1_BLOCK_SIZE;
+    size %= LEVEL1_BLOCK_SIZE;
+    let l2_blocks = size / LEVEL2_BLOCK_SIZE;
+    size %= LEVEL2_BLOCK_SIZE;
+    let l3_pages = size / GRANULARITY;
+
+    if !size.is_multiple_of(GRANULARITY) {
+        return Err(NovaError::Misalignment);
+    }
+
+    if l1_blocks > 0 {
+        todo!();
+    }
+
+    let mut addr = start_physical_address;
+    for _ in 0..l2_blocks {
+        reserve_block_explicit(addr)?;
+        addr += LEVEL2_BLOCK_SIZE;
+    }
+
+    for _ in 0..l3_pages {
+        reserve_page_explicit(addr)?;
+        addr += GRANULARITY;
+    }
+
+    Ok(start_physical_address)
+}
+
+fn virtual_address_to_table_offset(virtual_addr: usize) -> (usize, usize, usize) {
+    let absolute_page_off = (virtual_addr & !KERNEL_VIRTUAL_MEM_SPACE) / GRANULARITY;
+    let l3_off = absolute_page_off % TABLE_ENTRY_COUNT;
+    let l2_off = (absolute_page_off / TABLE_ENTRY_COUNT) % TABLE_ENTRY_COUNT;
+    let l1_off = (absolute_page_off / TABLE_ENTRY_COUNT / TABLE_ENTRY_COUNT) % TABLE_ENTRY_COUNT;
+    (l1_off, l2_off, l3_off)
+}
+
+/// Navigate the table tree, by following given offsets. This function
+/// allocates new tables if required.
+fn navigate_table(
+    initial_table_ptr: *mut PageTable,
+    offsets: &[usize],
+    create_missing: bool,
+) -> Result<*mut PageTable, NovaError> {
+    let mut table = initial_table_ptr;
+    for offset in offsets {
+        table = next_table(table, *offset, create_missing)?;
+    }
+    Ok(table)
+}
+
+/// Get the next table one level down.
+///
+/// If table doesn't exit a page will be allocated for it.
+fn next_table(
+    table_ptr: *mut PageTable,
+    offset: usize,
+    create_missing: bool,
+) -> Result<*mut PageTable, NovaError> {
+    let table = unsafe { &mut *table_ptr };
+    match table.0[offset].value & 0b11 {
+        0 => {
+            if !create_missing {
+                return Err(NovaError::Paging("No table defined."));
+            }
+            let new_phys_page_table_address = reserve_page();
+
+            table.0[offset] = TableEntry::table_descriptor(new_phys_page_table_address);
+            map_page(
+                phys_table_to_kernel_space(new_phys_page_table_address),
+                new_phys_page_table_address,
+                &raw mut TRANSLATIONTABLE_TTBR1,
+                NORMAL_MEM | WRITABLE | PXN | UXN,
+            )?;
+
+            Ok(resolve_table_addr(table.0[offset].address()) as *mut PageTable)
+        }
+        1 => Err(NovaError::Paging(
+            "Can't navigate table due to block mapping.",
+        )),
+        3 => Ok(resolve_table_addr(table.0[offset].address()) as *mut PageTable),
+        _ => unreachable!(),
+    }
+}
+
+/// Converts a physical table address and returns the corresponding virtual address depending on EL.
+///
+/// - `== EL0` -> panic
+/// - `== EL1` -> 0xFFFFFF82XXXXXXXX
+/// - `>= EL2` -> physical address
+#[inline]
+fn resolve_table_addr(physical_address: PhysAddr) -> VirtAddr {
+    let current_el = get_current_el();
+
+    if current_el >= 2 {
+        physical_address
+    } else if get_current_el() == 1 {
+        phys_table_to_kernel_space(physical_address)
+    } else {
+        panic!("Access to table entries is forbidden in EL0.")
+    }
+}
+
+/// Extracts the physical address out of an table entry.
+#[inline]
+fn phys_table_to_kernel_space(entry: usize) -> VirtAddr {
+    entry | TRANSLATION_TABLE_BASE_ADDR
 }

src/aarch64/mmu/physical_mapping.rs

@@ -0,0 +1,95 @@
+use crate::aarch64::mmu::{PhysAddr, GRANULARITY, L2_BLOCK_BITMAP_WORDS, MAX_PAGE_COUNT};
+use nova_error::NovaError;
+
+struct PagingMap {
+    bitmap: [u64; MAX_PAGE_COUNT / 64],
+}
+
+static mut PAGING_BITMAP: PagingMap = PagingMap {
+    bitmap: [0; MAX_PAGE_COUNT / 64],
+};
+
+pub fn reserve_page() -> PhysAddr {
+    if let Some(address) = find_unallocated_page() {
+        let page = address / GRANULARITY;
+        let word_index = page / 64;
+        unsafe { PAGING_BITMAP.bitmap[word_index] |= 1 << (page % 64) };
+        return address;
+    }
+    panic!("Out of Memory!");
+}
+
+pub fn reserve_page_explicit(physical_address: usize) -> Result<PhysAddr, NovaError> {
+    let page = physical_address / GRANULARITY;
+    let word_index = page / 64;
+
+    if unsafe { PAGING_BITMAP.bitmap[word_index] } & (1 << (page % 64)) > 0 {
+        return Err(NovaError::Paging("Page PA already taken."));
+    }
+
+    unsafe { PAGING_BITMAP.bitmap[word_index] |= 1 << (page % 64) };
+    Ok(physical_address)
+}
+
+pub fn reserve_block() -> usize {
+    if let Some(start) = find_contiguous_free_bitmap_words(L2_BLOCK_BITMAP_WORDS) {
+        for j in 0..L2_BLOCK_BITMAP_WORDS {
+            unsafe { PAGING_BITMAP.bitmap[start + j] = u64::MAX };
+        }
+        return start * 64 * GRANULARITY;
+    }
+
+    panic!("Out of Memory!");
+}
+
+pub fn reserve_block_explicit(physical_address: usize) -> Result<(), NovaError> {
+    let page = physical_address / GRANULARITY;
+    for i in 0..L2_BLOCK_BITMAP_WORDS {
+        unsafe {
+            if PAGING_BITMAP.bitmap[(page / 64) + i] != 0 {
+                return Err(NovaError::Paging("Block PA already taken."));
+            }
+        };
+    }
+    for i in 0..L2_BLOCK_BITMAP_WORDS {
+        unsafe {
+            PAGING_BITMAP.bitmap[(page / 64) + i] = u64::MAX;
+        };
+    }
+    Ok(())
+}
+
+fn find_unallocated_page() -> Option<usize> {
+    for (i, entry) in unsafe { PAGING_BITMAP.bitmap }.iter().enumerate() {
+        if *entry != u64::MAX {
+            for offset in 0..64 {
+                if entry >> offset & 0b1 == 0 {
+                    return Some((i * 64 + offset) * GRANULARITY);
+                }
+            }
+        }
+    }
+    None
+}
+
+fn find_contiguous_free_bitmap_words(required_words: usize) -> Option<usize> {
+    let mut run_start = 0;
+    let mut run_len = 0;
+
+    for (i, entry) in unsafe { PAGING_BITMAP.bitmap }.iter().enumerate() {
+        if *entry == 0 {
+            if run_len == 0 {
+                run_start = i;
+            }
+            run_len += 1;
+
+            if run_len == required_words {
+                return Some(run_start);
+            }
+        } else {
+            run_len = 0;
+        }
+    }
+
+    None
+}

src/aarch64/registers.rs

@@ -50,7 +50,9 @@ psr!(ESR_EL1, u32);
 
 psr!(SPSR_EL1, u32);
 
-psr!(ELR_EL1, u32);
+psr!(ELR_EL1, u64);
+
+psr!(SCTLR_EL1, u64);
 
 pub fn read_exception_source_el() -> u32 {
     read_spsr_el1() & 0b1111

src/application_manager.rs

@@ -0,0 +1,145 @@
+use crate::{
+    aarch64::mmu::{
+        find_free_kerne_page_in_block, map_page, physical_mapping::reserve_page, PageTable,
+        TableEntry, VirtAddr, NORMAL_MEM, TRANSLATIONTABLE_TTBR0, TRANSLATIONTABLE_TTBR1, WRITABLE,
+    },
+    configuration::memory_mapping::{APPLICATION_TRANSLATION_TABLE_VA, EL0_STACK_TOP},
+};
+use alloc::vec::Vec;
+use core::{arch::asm, mem, ptr::write_volatile};
+use log::error;
+use nova_error::NovaError;
+use spin::Mutex;
+
+struct AppManager {
+    apps: Option<Vec<Application>>,
+}
+
+impl AppManager {
+    const fn new() -> Self {
+        Self { apps: None }
+    }
+}
+
+unsafe impl Send for AppManager {}
+
+pub struct Application {
+    pub table_ptr: *mut TableEntry,
+    pub start_addr: usize,
+    pub stack_pointer: usize,
+}
+
+impl Application {
+    pub fn new(start_addr: VirtAddr) -> Self {
+        let physical_addr = reserve_page();
+        let virtual_address =
+            find_free_kerne_page_in_block(APPLICATION_TRANSLATION_TABLE_VA).unwrap();
+
+        map_page(
+            virtual_address,
+            physical_addr,
+            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1),
+            NORMAL_MEM | WRITABLE,
+        )
+        .unwrap();
+
+        // TODO: Temporary solution, while kernel and app share some memory regions
+        #[allow(static_mut_refs)]
+        unsafe {
+            let table = &mut *(virtual_address as *mut PageTable);
+            table.0 = TRANSLATIONTABLE_TTBR0.0;
+        }
+
+        Self {
+            table_ptr: physical_addr as *mut TableEntry,
+            start_addr,
+            stack_pointer: EL0_STACK_TOP,
+        }
+    }
+
+    pub unsafe fn configure_registers(&self) {
+        asm!("msr ELR_EL1, {}", in(reg) self.start_addr);
+        asm!("msr SPSR_EL1, {0:x}", in(reg) 0);
+        asm!("msr SP_EL0, {0:x}", in(reg) self.stack_pointer);
+        asm!("msr TTBR0_EL1, {}", in(reg) self.table_ptr as usize);
+    }
+
+    /// Starts an application.
+    ///
+    /// `ELR_EL1` ->  Exception Link Register (starting virtual address)
+    /// `SPSR_EL1` -> Saved Program State Register (settings for `eret` behaviour)
+    /// `SP_EL0` -> Stack Pointer Register (virtual_address of stack Pointer)
+    /// `TTBR0_EL1` -> Translation Table base Register Register
+    pub fn start(&mut self, args: Vec<&str>) {
+        let size = args.len();
+        let argv = self.construct_inital_stack(args);
+        unsafe {
+            self.configure_registers();
+            asm!("", in("x0") size, in("x1") argv);
+            asm!("eret");
+        }
+    }
+
+    /// Initializes the stack based on the System V ABI
+    fn construct_inital_stack(&mut self, args: Vec<&str>) -> usize {
+        let size = args.len();
+        let mut arg_addresses = Vec::with_capacity(size);
+
+        // Write strings into stack
+        for value in args {
+            self.stack_pointer -= value.len() * mem::size_of::<u8>();
+            let pointer = self.stack_pointer as *mut u8;
+            unsafe { core::ptr::copy(value.as_ptr(), pointer, value.len()) };
+            arg_addresses.push(pointer);
+        }
+        self.stack_pointer = align_down(self.stack_pointer, 16);
+
+        // TODO: Auxiliry vector entry
+        // TODO: Environment pointers
+
+        let argv = self.stack_pointer;
+
+        // Write argument pointers into stack
+        for addr in arg_addresses {
+            unsafe { write_volatile(self.stack_pointer as *mut *const u8, addr) };
+            self.stack_pointer -= mem::size_of::<*const u8>();
+        }
+
+        argv
+    }
+}
+
+fn align_down(sp: usize, align: usize) -> usize {
+    sp & !(align - 1)
+}
+
+static APP_MANAGER: Mutex<AppManager> = Mutex::new(AppManager::new());
+
+pub fn initialize_app_manager() {
+    let mut guard = APP_MANAGER.lock();
+    guard.apps = Some(Vec::new());
+}
+
+pub fn add_app(app: Application) -> Result<(), NovaError> {
+    if let Some(app_list) = APP_MANAGER.lock().apps.as_mut() {
+        app_list.push(app);
+        Ok(())
+    } else {
+        Err(NovaError::General("AppManager not initalized."))
+    }
+}
+
+pub fn start_app(index: usize, args: Vec<&str>) -> Result<(), NovaError> {
+    if let Some(app) = APP_MANAGER
+        .lock()
+        .apps
+        .as_mut()
+        .and_then(|am| am.get_mut(index))
+    {
+        app.start(args);
+        unreachable!()
+    } else {
+        error!("Unable to start app due to invalid App ID.");
+        Err(NovaError::General("Invalid app id."))
+    }
+}

src/config.S

@@ -0,0 +1,80 @@
+.section .text.config
+.align 4
+.global el2_to_el1
+el2_to_el1:
+    mov x0, #(1 << 31)
+    msr HCR_EL2, x0
+
+    // Set SPSR_EL2: return to EL1h
+    mov x0, #(0b0101)
+    msr SPSR_EL2, x0
+
+    // Set return address to kernel_main
+    adrp x0, KERNEL_VIRTUAL_MEM_SPACE
+    ldr x1, [x0, :lo12:KERNEL_VIRTUAL_MEM_SPACE]
+
+    adrp x0, kernel_main
+    add  x0, x0, :lo12:kernel_main
+    orr  x0, x0, x1
+    msr ELR_EL2, x0
+
+    // Set SP_EL1 to stack base
+    adrp x0, EL1_STACK_TOP
+    ldr  x1, [x0, :lo12:EL1_STACK_TOP]
+    msr SP_EL1, x1
+
+    // Set VBAR_EL1 to vector table
+    adrp x0, vector_table
+    add  x0, x0, :lo12:vector_table
+    msr VBAR_EL1, x0
+
+    isb
+
+    adrp x0, SCTLR_EL1_CONF
+    ldr  x1, [x0, :lo12:SCTLR_EL1_CONF]
+    msr SCTLR_EL1, x1
+
+    isb
+
+    // SIMD should not be trapped
+    mrs x0, CPACR_EL1
+    mov x1, #(0b11<<20)
+    orr x0,x0, x1
+    msr CPACR_EL1,x0
+
+    isb
+
+    // Return to EL1
+    eret
+
+.section .text.config
+.align 4
+.global configure_mmu_el1
+configure_mmu_el1:
+    // Configure MMU
+    adrp x0, TCR_EL1_CONF
+    ldr  x1, [x0, :lo12:TCR_EL1_CONF]
+    msr TCR_EL1, x1
+    isb
+
+    // MAIR0: Normal Mem.
+    // MAIR1: Device Mem.
+    mov x0, #0x04FF
+    msr MAIR_EL1, x0
+    isb
+
+    // Configure translation table
+    adrp x0, TRANSLATIONTABLE_TTBR0
+    add  x1, x0, :lo12:TRANSLATIONTABLE_TTBR0
+    msr TTBR0_EL1, x1
+
+    adrp x0, TRANSLATIONTABLE_TTBR1
+    add  x1, x0, :lo12:TRANSLATIONTABLE_TTBR1
+    msr TTBR1_EL1, x1
+
+    tlbi vmalle1
+    dsb ish
+    isb
+
+    ret
+

src/configuration.rs

@@ -1,16 +1,34 @@
-static SCTLR_EL1_MMU_DISABLED: u64 = 0; //M
+const SCTLR_EL1_MMU_ENABLED: u64 = 1; //M
-static SCTLR_EL1_DATA_CACHE_DISABLED: u64 = 0 << 2; //C
+const SCTLR_EL1_DATA_CACHE_DISABLED: u64 = 0 << 2; //C
-static SCTLR_EL1_INSTRUCTION_CACHE_DISABLED: u64 = 0 << 12; //I
+const SCTLR_EL1_INSTRUCTION_CACHE_DISABLED: u64 = 0 << 12; //I
-static SCTLR_EL1_LITTLE_ENDIAN_EL0: u64 = 0 << 24; //E0E
+const SCTLR_EL1_LITTLE_ENDIAN_EL0: u64 = 0 << 24; //E0E
-static SCTLR_EL1_LITTLE_ENDIAN_EL1: u64 = 0 << 25; //EE
+const SCTLR_EL1_LITTLE_ENDIAN_EL1: u64 = 0 << 25; //EE
+const SCTLR_EL1_SPAN: u64 = 1 << 23; //SPAN
 
 #[allow(clippy::identity_op)]
-static SCTLR_EL1_RES: u64 = (0 << 6) | (1 << 11) | (0 << 17) | (1 << 20) | (1 << 22); //Res0 & Res1
+const SCTLR_EL1_RES: u64 = (0 << 6) | (1 << 11) | (0 << 17) | (1 << 20) | (1 << 22); //Res0 & Res1
 
 #[no_mangle]
-pub static SCTLR_EL1_CONF: u64 = SCTLR_EL1_MMU_DISABLED
+pub static SCTLR_EL1_CONF: u64 = SCTLR_EL1_MMU_ENABLED
     | SCTLR_EL1_DATA_CACHE_DISABLED
     | SCTLR_EL1_INSTRUCTION_CACHE_DISABLED
     | SCTLR_EL1_LITTLE_ENDIAN_EL0
     | SCTLR_EL1_LITTLE_ENDIAN_EL1
-    | SCTLR_EL1_RES;
+    | SCTLR_EL1_RES
+    | SCTLR_EL1_SPAN;
+
+const TG0: u64 = 0b00 << 14; // 4KB granularity EL0
+const T0SZ: u64 = 25; // 25 Bits of TTBR select -> 39 Bits of VA
+const SH0: u64 = 0b11 << 12; // Inner shareable
+
+const TG1: u64 = 0b10 << 30; // 4KB granularity EL1
+const T1SZ: u64 = 25 << 16; // 25 Bits of TTBR select -> 39 Bits of VA
+const SH1: u64 = 0b11 << 28; // Inner sharable
+
+const IPS: u64 = 0b000 << 32; // 32 bits of PA space -> up to 4GiB
+const AS: u64 = 0b1 << 36; // configure an ASID size of 16 bits
+
+#[no_mangle]
+pub static TCR_EL1_CONF: u64 = IPS | TG0 | TG1 | T0SZ | T1SZ | SH0 | SH1 | AS;
+
+pub mod memory_mapping;

src/configuration/memory_mapping.rs

@@ -0,0 +1,127 @@
+use crate::{
+    aarch64::mmu::{
+        alloc_block_l2_explicit, allocate_memory, map_page, physical_mapping::reserve_page,
+        reserve_range, PhysAddr, PhysSource, VirtAddr, DEVICE_MEM, EL0_ACCESSIBLE, GRANULARITY,
+        KERNEL_VIRTUAL_MEM_SPACE, LEVEL1_BLOCK_SIZE, LEVEL2_BLOCK_SIZE, NORMAL_MEM, PXN, READ_ONLY,
+        STACK_START_ADDR, TRANSLATIONTABLE_TTBR0, TRANSLATIONTABLE_TTBR1, UXN, WRITABLE,
+    },
+    PERIPHERAL_BASE,
+};
+
+#[no_mangle]
+static EL1_STACK_TOP: usize = STACK_START_ADDR | KERNEL_VIRTUAL_MEM_SPACE;
+const EL1_STACK_SIZE: usize = LEVEL2_BLOCK_SIZE * 2;
+#[no_mangle]
+pub static EL0_STACK_TOP: usize = STACK_START_ADDR;
+pub const EL0_STACK_SIZE: usize = LEVEL2_BLOCK_SIZE * 2;
+
+pub const MAILBOX_VIRTUAL_ADDRESS: VirtAddr = 0xFFFF_FF81_FFFF_E000;
+pub static mut MAILBOX_PHYSICAL_ADDRESS: Option<PhysAddr> = None;
+
+// TODO: Currently limited to 512 applications, more than enough, but has to be kept
+// in mind
+pub const APPLICATION_TRANSLATION_TABLE_VA: VirtAddr = 0xFFFF_FF81_FE00_0000;
+
+extern "C" {
+    static __text_end: u64;
+    static __share_end: u64;
+    static __kernel_end: u64;
+}
+
+pub fn initialize_mmu_translation_tables() {
+    let text_end = unsafe { &__text_end } as *const _ as usize;
+    let shared_segment_end = unsafe { &__share_end } as *const _ as usize;
+    let kernel_end = unsafe { &__kernel_end } as *const _ as usize;
+
+    reserve_range(0x0, kernel_end).unwrap();
+
+    for addr in (0..text_end).step_by(GRANULARITY) {
+        map_page(
+            addr,
+            addr,
+            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
+            EL0_ACCESSIBLE | READ_ONLY | NORMAL_MEM,
+        )
+        .unwrap();
+    }
+
+    for addr in (0..text_end).step_by(GRANULARITY) {
+        map_page(
+            addr | KERNEL_VIRTUAL_MEM_SPACE,
+            addr,
+            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1),
+            READ_ONLY | NORMAL_MEM,
+        )
+        .unwrap();
+    }
+
+    for addr in (text_end..shared_segment_end).step_by(GRANULARITY) {
+        map_page(
+            addr,
+            addr,
+            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
+            EL0_ACCESSIBLE | WRITABLE | NORMAL_MEM,
+        )
+        .unwrap();
+    }
+
+    for addr in (text_end..shared_segment_end).step_by(GRANULARITY) {
+        map_page(
+            addr | KERNEL_VIRTUAL_MEM_SPACE,
+            addr,
+            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR1),
+            EL0_ACCESSIBLE | WRITABLE | NORMAL_MEM,
+        )
+        .unwrap();
+    }
+
+    for addr in (PERIPHERAL_BASE..LEVEL1_BLOCK_SIZE).step_by(LEVEL2_BLOCK_SIZE) {
+        alloc_block_l2_explicit(
+            addr,
+            addr,
+            core::ptr::addr_of_mut!(TRANSLATIONTABLE_TTBR0),
+            EL0_ACCESSIBLE | WRITABLE | UXN | PXN | DEVICE_MEM,
+        )
+        .unwrap();
+    }
+
+    // Frame Buffer memory range
+    allocate_memory(
+        0x3c100000,
+        1080 * 1920 * 4,
+        PhysSource::Explicit(0x3c100000),
+        NORMAL_MEM | PXN | UXN | WRITABLE | EL0_ACCESSIBLE,
+    )
+    .unwrap();
+
+    // Allocate EL1 stack
+    allocate_memory(
+        EL1_STACK_TOP - EL1_STACK_SIZE + 0x10,
+        EL1_STACK_SIZE,
+        PhysSource::Any,
+        WRITABLE | NORMAL_MEM,
+    )
+    .unwrap();
+
+    // Allocate EL0 stack
+    allocate_memory(
+        EL0_STACK_TOP - EL0_STACK_SIZE + 0x10,
+        EL0_STACK_SIZE,
+        PhysSource::Any,
+        WRITABLE | EL0_ACCESSIBLE | NORMAL_MEM,
+    )
+    .unwrap();
+
+    // Allocate Mailbox buffer
+    {
+        let addr = reserve_page();
+        unsafe { MAILBOX_PHYSICAL_ADDRESS = Some(addr) };
+        allocate_memory(
+            MAILBOX_VIRTUAL_ADDRESS,
+            GRANULARITY,
+            PhysSource::Explicit(addr),
+            WRITABLE | NORMAL_MEM,
+        )
+        .unwrap();
+    }
+}

src/console.rs

@@ -0,0 +1,92 @@
+use alloc::string::String;
+
+use crate::{
+    application_manager::start_app,
+    interrupt_handlers::irq::{register_interrupt_handler, IRQSource},
+    peripherals::uart::read_uart_data,
+    pi3::mailbox::read_soc_temp,
+    print, println,
+};
+
+pub static mut TERMINAL: Option<Terminal> = None;
+
+pub struct Terminal {
+    input: String,
+}
+
+impl Default for Terminal {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Terminal {
+    pub fn new() -> Self {
+        Self {
+            input: String::new(),
+        }
+    }
+
+    fn flush(&mut self) {
+        print!("\n> {}", self.input);
+    }
+
+    fn exec(&mut self) {
+        print!("\n");
+        let val = self.input.clone();
+        self.input.clear();
+
+        let mut parts = val.split(" ");
+
+        match parts.next().unwrap() {
+            "temp" => {
+                println!("{}", read_soc_temp([0]).unwrap()[1]);
+            }
+            "app" => {
+                if let Some(app_id) = parts.next().and_then(|a| a.parse::<usize>().ok()) {
+                    let args = parts.collect();
+                    let _ = start_app(app_id, args);
+                } else {
+                    println!("App ID not set.");
+                }
+            }
+            _ => {
+                println!("Unknown command: \"{}\"", self.input);
+            }
+        }
+        self.input.clear();
+    }
+}
+
+pub fn init_terminal() {
+    unsafe { TERMINAL = Some(Terminal::new()) };
+    register_terminal_interrupt_handler();
+}
+
+fn terminal_uart_rx_interrupt_handler() {
+    let input = read_uart_data();
+    #[allow(static_mut_refs)]
+    if let Some(term) = unsafe { TERMINAL.as_mut() } {
+        match input {
+            '\r' => {
+                term.exec();
+                term.flush();
+            }
+            _ => {
+                term.input.push(input);
+                print!("{}", input);
+            }
+        }
+    }
+}
+
+pub fn flush_terminal() {
+    #[allow(static_mut_refs)]
+    if let Some(term) = unsafe { TERMINAL.as_mut() } {
+        term.flush();
+    }
+}
+
+fn register_terminal_interrupt_handler() {
+    register_interrupt_handler(IRQSource::UartInt, terminal_uart_rx_interrupt_handler);
+}

src/framebuffer.rs

@@ -4,10 +4,8 @@ mod bitmaps;
 
 use bitmaps::BASIC_LEGACY;
 
-use crate::{
+use crate::pi3::mailbox::{read_mailbox, write_mailbox};
-    pi3::mailbox::{read_mailbox, write_mailbox},
+use log::error;
-    println,
-};
 #[repr(align(16))]
 struct Mailbox([u32; 36]);
 
@@ -24,8 +22,8 @@ pub struct FrameBuffer {
     pixel_depth: u32, // Bits per pixel
     pitch: u32,       // Pixel per row
     rows: u32,        // Rows
-    start_addr: *mut u32,
+    pub start_addr: *mut u32,
-    size: u32, //Bytes
+    pub size: u32, //Bytes
 }
 
 pub const RED: u32 = 0x00FF0000;
@@ -37,6 +35,9 @@ pub const YELLOW: u32 = 0x00FFFF00;
 impl FrameBuffer {
     pub fn draw_pixel(&self, x: u32, y: u32, color: u32) {
         let offset = x + y * self.pitch;
+        if x >= self.pitch || y >= self.rows {
+            return;
+        }
         unsafe {
             write_volatile(self.start_addr.add(offset as usize), color);
         }
@@ -234,7 +235,7 @@ impl Default for FrameBuffer {
 
         let _ = read_mailbox(8);
         if mailbox.0[1] == 0 {
-            println!("Failed");
+            error!("Mailbox request was not processed!");
         }
 
         mailbox.0[28] &= 0x3FFFFFFF;

src/interrupt_handlers.rs

@@ -1,19 +1,10 @@
 use core::arch::asm;
 
-use alloc::vec::Vec;
-
 use crate::{
-    aarch64::registers::{
+    aarch64::registers::{daif::mask_all, read_esr_el1, read_exception_source_el},
-        daif::{mask_all, unmask_irq},
-        read_esr_el1, read_exception_source_el,
-    },
     get_current_el,
-    peripherals::{
-        gpio::{read_gpio_event_detect_status, reset_gpio_event_detect_status},
-        uart::clear_uart_interrupt_state,
-    },
-    println, read_address, write_address,
 };
+use log::debug;
 
 const INTERRUPT_BASE: u32 = 0x3F00_B000;
 const IRQ_PENDING_BASE: u32 = INTERRUPT_BASE + 0x204;
@@ -22,30 +13,29 @@ const DISABLE_IRQ_BASE: u32 = INTERRUPT_BASE + 0x21C;
 
 const GPIO_PENDING_BIT_OFFSET: u64 = 0b1111 << 49;
 
-struct InterruptHandlers {
+#[repr(C)]
-    source: IRQSource,
+pub struct TrapFrame {
-    function: fn(),
+    pub x0: u64,
-}
+    pub x1: u64,
-
+    pub x2: u64,
-// TODO: replace with hashmap and check for better alternatives for option
+    pub x3: u64,
-static mut INTERRUPT_HANDLERS: Option<Vec<InterruptHandlers>> = None;
+    pub x4: u64,
-
+    pub x5: u64,
-#[derive(Clone)]
+    pub x6: u64,
-#[repr(u32)]
+    pub x7: u64,
-pub enum IRQSource {
+    pub x8: u64,
-    AuxInt = 29,
+    pub x9: u64,
-    I2cSpiSlvInt = 44,
+    pub x10: u64,
-    Pwa0 = 45,
+    pub x11: u64,
-    Pwa1 = 46,
+    pub x12: u64,
-    Smi = 48,
+    pub x13: u64,
-    GpioInt0 = 49,
+    pub x14: u64,
-    GpioInt1 = 50,
+    pub x15: u64,
-    GpioInt2 = 51,
+    pub x16: u64,
-    GpioInt3 = 52,
+    pub x17: u64,
-    I2cInt = 53,
+    pub x18: u64,
-    SpiInt = 54,
+    pub x29: u64,
-    PcmInt = 55,
+    pub x30: u64,
-    UartInt = 57,
 }
 
 /// Representation of the ESR_ELx registers
@@ -69,155 +59,25 @@ impl From<u32> for EsrElX {
     }
 }
 
-#[no_mangle]
+pub mod irq;
-unsafe extern "C" fn rust_irq_handler() {
+pub mod synchronous;
-    mask_all();
-    let pending_irqs = get_irq_pending_sources();
-
-    if pending_irqs & GPIO_PENDING_BIT_OFFSET != 0 {
-        handle_gpio_interrupt();
-        let source_el = read_exception_source_el() >> 2;
-        println!("Source EL: {}", source_el);
-        println!("Current EL: {}", get_current_el());
-        println!("Return register address: {:#x}", read_esr_el1());
-    }
-
-    if let Some(handler_vec) = unsafe { INTERRUPT_HANDLERS.as_ref() } {
-        for handler in handler_vec {
-            if (pending_irqs & (1 << (handler.source.clone() as u32))) != 0 {
-                (handler.function)();
-                clear_interrupt_for_source(handler.source.clone());
-            }
-        }
-    }
-}
 
 #[no_mangle]
 unsafe extern "C" fn rust_synchronous_interrupt_no_el_change() {
     mask_all();
 
     let source_el = read_exception_source_el() >> 2;
-    println!("--------Sync Exception in EL{}--------", source_el);
+    debug!("--------Sync Exception in EL{}--------", source_el);
-    println!("No EL change");
+    debug!("No EL change");
-    println!("Current EL: {}", get_current_el());
+    debug!("Current EL: {}", get_current_el());
-    println!("{:?}", EsrElX::from(read_esr_el1()));
+    debug!("{:?}", EsrElX::from(read_esr_el1()));
-    println!("Return register address: {:#x}", read_esr_el1());
+    debug!("Return register address: {:#x}", read_esr_el1());
-    println!("-------------------------------------");
+    debug!("-------------------------------------");
 }
 
-/// Synchronous Exception Handler
+fn set_return_to_kernel_loop() {
-///
-/// Lower Exception level, where the implemented level
-/// immediately lower than the target level is using
-/// AArch64.
-#[no_mangle]
-unsafe extern "C" fn rust_synchronous_interrupt_imm_lower_aarch64() {
-    mask_all();
-
-    let source_el = read_exception_source_el() >> 2;
-    println!("--------Sync Exception in EL{}--------", source_el);
-    println!("Exception escalated to EL {}", get_current_el());
-    println!("Current EL: {}", get_current_el());
-    let esr = EsrElX::from(read_esr_el1());
-    println!("{:?}", EsrElX::from(esr));
-    println!("Return register address: {:#x}", read_esr_el1());
-
-    match esr.ec {
-        0b100100 => {
-            println!("Cause: Data Abort from a lower Exception level");
-        }
-        _ => {}
-    }
-    println!("-------------------------------------");
-
-    set_return_to_kernel_main();
-}
-
-fn clear_interrupt_for_source(source: IRQSource) {
-    match source {
-        IRQSource::UartInt => clear_uart_interrupt_state(),
-        _ => {}
-    }
-}
-
-fn set_return_to_kernel_main() {
     unsafe {
-        asm!("ldr x0, =kernel_main", "msr ELR_EL1, x0");
+        asm!("ldr x0, =kernel_loop", "msr ELR_EL1, x0");
         asm!("mov x0, #(0b0101)", "msr SPSR_EL1, x0");
     }
 }
-
-fn handle_gpio_interrupt() {
-    println!("Interrupt");
-    for i in 0..=53u32 {
-        let val = read_gpio_event_detect_status(i);
-
-        if val {
-            #[allow(clippy::single_match)]
-            match i {
-                26 => {
-                    println!("Button Pressed");
-                }
-                _ => {}
-            }
-            // Reset GPIO Interrupt handler by writing a 1
-            reset_gpio_event_detect_status(i);
-        }
-    }
-    unmask_irq();
-}
-
-/// Enables IRQ Source
-pub fn enable_irq_source(state: IRQSource) {
-    let nr = state as u32;
-    let register = ENABLE_IRQ_BASE + 4 * (nr / 32);
-    let register_offset = nr % 32;
-    let current = unsafe { read_address(register) };
-    let mask = 0b1 << register_offset;
-    let new_val = current | mask;
-    unsafe { write_address(register, new_val) };
-}
-
-/// Disable IRQ Source
-pub fn disable_irq_source(state: IRQSource) {
-    let nr = state as u32;
-    let register = DISABLE_IRQ_BASE + 4 * (nr / 32);
-    let register_offset = nr % 32;
-    let current = unsafe { read_address(register) };
-    let mask = 0b1 << register_offset;
-    let new_val = current | mask;
-    unsafe { write_address(register, new_val) };
-}
-
-/// Read current IRQ Source status
-pub fn read_irq_source_status(state: IRQSource) -> u32 {
-    let nr = state as u32;
-    let register = ENABLE_IRQ_BASE + 4 * (nr / 32);
-    let register_offset = nr % 32;
-    (unsafe { read_address(register) } >> register_offset) & 0b1
-}
-
-/// Status if a IRQ Source is pending
-pub fn is_irq_source_pending(state: IRQSource) -> bool {
-    let nr = state as u32;
-    let register = IRQ_PENDING_BASE + 4 * (nr / 32);
-    let register_offset = nr % 32;
-    ((unsafe { read_address(register) } >> register_offset) & 0b1) != 0
-}
-
-/// Status if a IRQ Source is pending
-pub fn get_irq_pending_sources() -> u64 {
-    let mut pending = unsafe { read_address(IRQ_PENDING_BASE + 4) as u64 } << 32;
-    pending |= unsafe { read_address(IRQ_PENDING_BASE) as u64 };
-    pending
-}
-
-pub fn initialize_interrupt_handler() {
-    unsafe { INTERRUPT_HANDLERS = Some(Vec::new()) };
-}
-
-pub fn register_interrupt_handler(source: IRQSource, function: fn()) {
-    if let Some(handler_vec) = unsafe { INTERRUPT_HANDLERS.as_mut() } {
-        handler_vec.push(InterruptHandlers { source, function });
-    }
-}

src/interrupt_handlers/irq.rs

@@ -0,0 +1,152 @@
+use crate::aarch64::registers::read_esr_el1;
+use crate::{
+    aarch64::registers::{
+        daif::{mask_all, unmask_irq},
+        read_exception_source_el,
+    },
+    get_current_el,
+    interrupt_handlers::{
+        DISABLE_IRQ_BASE, ENABLE_IRQ_BASE, GPIO_PENDING_BIT_OFFSET, IRQ_PENDING_BASE,
+    },
+    peripherals::{
+        gpio::{read_gpio_event_detect_status, reset_gpio_event_detect_status},
+        uart::clear_uart_interrupt_state,
+    },
+    read_address, write_address,
+};
+use alloc::vec::Vec;
+use log::{debug, info};
+
+struct InterruptHandlers {
+    source: IRQSource,
+    function: fn(),
+}
+
+// TODO: replace with hashmap and check for better alternatives for option
+static mut INTERRUPT_HANDLERS: Option<Vec<InterruptHandlers>> = None;
+
+#[derive(Clone)]
+#[repr(u32)]
+pub enum IRQSource {
+    AuxInt = 29,
+    I2cSpiSlvInt = 44,
+    Pwa0 = 45,
+    Pwa1 = 46,
+    Smi = 48,
+    GpioInt0 = 49,
+    GpioInt1 = 50,
+    GpioInt2 = 51,
+    GpioInt3 = 52,
+    I2cInt = 53,
+    SpiInt = 54,
+    PcmInt = 55,
+    UartInt = 57,
+}
+
+#[inline(always)]
+pub fn initialize_interrupt_handler() {
+    unsafe { INTERRUPT_HANDLERS = Some(Vec::new()) };
+}
+
+pub fn register_interrupt_handler(source: IRQSource, function: fn()) {
+    if let Some(handler_vec) = unsafe { &mut *core::ptr::addr_of_mut!(INTERRUPT_HANDLERS) } {
+        handler_vec.push(InterruptHandlers { source, function });
+    }
+}
+
+#[no_mangle]
+unsafe extern "C" fn rust_irq_handler() {
+    mask_all();
+    let pending_irqs = get_irq_pending_sources();
+
+    if pending_irqs & GPIO_PENDING_BIT_OFFSET != 0 {
+        handle_gpio_interrupt();
+        let source_el = read_exception_source_el() >> 2;
+        debug!("Source EL: {}", source_el);
+        debug!("Current EL: {}", get_current_el());
+        debug!("Return register address: {:#x}", read_esr_el1());
+    }
+
+    if let Some(handler_vec) = unsafe { &*core::ptr::addr_of_mut!(INTERRUPT_HANDLERS) } {
+        for handler in handler_vec {
+            if (pending_irqs & (1 << (handler.source.clone() as u32))) != 0 {
+                (handler.function)();
+                clear_interrupt_for_source(handler.source.clone());
+            }
+        }
+    }
+}
+
+fn handle_gpio_interrupt() {
+    debug!("GPIO interrupt triggered");
+    for i in 0..=53u32 {
+        let val = read_gpio_event_detect_status(i);
+
+        if val {
+            #[allow(clippy::single_match)]
+            match i {
+                26 => {
+                    info!("Button Pressed");
+                }
+                _ => {}
+            }
+            // Reset GPIO Interrupt handler by writing a 1
+            reset_gpio_event_detect_status(i);
+        }
+    }
+    unmask_irq();
+}
+
+/// Enables IRQ Source
+pub fn enable_irq_source(state: IRQSource) {
+    let nr = state as u32;
+    let register = ENABLE_IRQ_BASE + 4 * (nr / 32);
+    let register_offset = nr % 32;
+    let current = unsafe { read_address(register) };
+    let mask = 0b1 << register_offset;
+    let new_val = current | mask;
+    unsafe { write_address(register, new_val) };
+}
+
+/// Disable IRQ Source
+pub fn disable_irq_source(state: IRQSource) {
+    let nr = state as u32;
+    let register = DISABLE_IRQ_BASE + 4 * (nr / 32);
+    let register_offset = nr % 32;
+    let current = unsafe { read_address(register) };
+    let mask = 0b1 << register_offset;
+    let new_val = current | mask;
+    unsafe { write_address(register, new_val) };
+}
+
+/// Read current IRQ Source status
+pub fn read_irq_source_status(state: IRQSource) -> u32 {
+    let nr = state as u32;
+    let register = ENABLE_IRQ_BASE + 4 * (nr / 32);
+    let register_offset = nr % 32;
+    (unsafe { read_address(register) } >> register_offset) & 0b1
+}
+
+/// Status if a IRQ Source is pending
+pub fn is_irq_source_pending(state: IRQSource) -> bool {
+    let nr = state as u32;
+    let register = IRQ_PENDING_BASE + 4 * (nr / 32);
+    let register_offset = nr % 32;
+    ((unsafe { read_address(register) } >> register_offset) & 0b1) != 0
+}
+
+/// Status if a IRQ Source is pending
+pub fn get_irq_pending_sources() -> u64 {
+    let mut pending = unsafe { read_address(IRQ_PENDING_BASE + 4) as u64 } << 32;
+    pending |= unsafe { read_address(IRQ_PENDING_BASE) as u64 };
+    pending
+}
+
+fn clear_interrupt_for_source(source: IRQSource) {
+    match source {
+        IRQSource::UartInt => clear_uart_interrupt_state(),
+        _ => {
+            todo!()
+        }
+    }
+}

src/interrupt_handlers/synchronous.rs

@@ -0,0 +1,116 @@
+use crate::{
+    aarch64::registers::{daif::mask_all, read_elr_el1, read_esr_el1, read_exception_source_el},
+    get_current_el,
+    interrupt_handlers::{set_return_to_kernel_loop, EsrElX, TrapFrame},
+    pi3::mailbox,
+};
+
+use log::{debug, error, warn};
+
+/// Synchronous Exception Handler
+///
+/// Source is a lower Exception level, where the implemented level
+/// immediately lower than the target level is using
+/// AArch64.
+#[no_mangle]
+unsafe extern "C" fn rust_synchronous_interrupt_imm_lower_aarch64(frame: &mut TrapFrame) -> usize {
+    mask_all();
+    let esr: EsrElX = EsrElX::from(read_esr_el1());
+    debug!("Synchronous interrupt from lower EL triggered");
+    log_sync_exception();
+    match esr.ec {
+        0b100100 => {
+            error!("Data Abort from a lower Exception level");
+            error!("Cause: {}", decode_data_abort(esr.iss as usize));
+        }
+        0b010101 => {
+            debug!("SVC instruction execution in AArch64");
+            return handle_svc(frame);
+        }
+        0b100010 => {
+            error!("PC alignment fault.");
+        }
+        _ => {
+            error!("Synchronous interrupt: Unknown Error Code: {:b}", esr.ec);
+        }
+    }
+
+    warn!("UnhandledException -> Returning to kernel...");
+    set_return_to_kernel_loop();
+    0
+}
+
+fn decode_data_abort(iss: usize) -> &'static str {
+    match iss & 0b111111 {
+        0b000000 => "Address size fault, level 0",
+        0b000001 => "Address size fault, level 1",
+        0b000010 => "Address size fault, level 2",
+        0b000011 => "Address size fault, level 3",
+
+        0b000100 => "Translation fault, level 0",
+        0b000101 => "Translation fault, level 1",
+        0b000110 => "Translation fault, level 2",
+        0b000111 => "Translation fault, level 3",
+
+        0b001001 => "Access flag fault, level 1",
+        0b001010 => "Access flag fault, level 2",
+        0b001011 => "Access flag fault, level 3",
+
+        0b001101 => "Permission fault, level 1",
+        0b001110 => "Permission fault, level 2",
+        0b001111 => "Permission fault, level 3",
+
+        0b010000 => "Synchronous External abort, not on translation table walk",
+        0b011000 => {
+            "Synchronous parity or ECC error on memory access, not on translation table walk"
+        }
+
+        0b010100 => "Synchronous External abort, on translation table walk, level 0",
+        0b010101 => "Synchronous External abort, on translation table walk, level 1",
+        0b010110 => "Synchronous External abort, on translation table walk, level 2",
+        0b010111 => "Synchronous External abort, on translation table walk, level 3",
+
+        0b011100 => "Synchronous parity or ECC error on translation table walk, level 0",
+        0b011101 => "Synchronous parity or ECC error on translation table walk, level 1",
+        0b011110 => "Synchronous parity or ECC error on translation table walk, level 2",
+        0b011111 => "Synchronous parity or ECC error on translation table walk, level 3",
+
+        0b100001 => "Alignment fault",
+        0b110000 => "TLB conflict abort",
+        0b110001 => "Unsupported atomic hardware update fault",
+
+        0b110100 => "IMPLEMENTATION DEFINED fault (Lockdown)",
+        0b110101 => "IMPLEMENTATION DEFINED fault (Unsupported Exclusive or Atomic access)",
+
+        0b111101 => "Section Domain Fault",
+        0b111110 => "Page Domain Fault",
+
+        _ => "Reserved / Unknown",
+    }
+}
+
+fn handle_svc(frame: &mut TrapFrame) -> usize {
+    match frame.x8 {
+        0 => {
+            debug!("Program exited!");
+            set_return_to_kernel_loop();
+            0
+        }
+        67 => {
+            let response = mailbox::read_soc_temp([0]).unwrap();
+            response[1] as usize
+        }
+        _ => 0,
+    }
+}
+
+fn log_sync_exception() {
+    let source_el = read_exception_source_el() >> 2;
+    debug!("--------Sync Exception in EL{}--------", source_el);
+    debug!("Exception escalated to EL {}", get_current_el());
+    debug!("Current EL: {}", get_current_el());
+    let esr: EsrElX = EsrElX::from(read_esr_el1());
+    debug!("{:?}", esr);
+    debug!("Return address: {:#x}", read_elr_el1());
+    debug!("-------------------------------------");
+}

src/lib.rs

@@ -3,39 +3,51 @@
 
 extern crate alloc;
 
-use alloc::boxed::Box;
 use core::{
     arch::asm,
     panic::PanicInfo,
     ptr::{read_volatile, write_volatile},
 };
+use log::LevelFilter;
+use log::{Level, Metadata, Record};
 
 use heap::Heap;
 
-use crate::{interrupt_handlers::initialize_interrupt_handler, logger::DefaultLogger};
+use crate::{
+    aarch64::mmu::{
+        allocate_memory, PhysSource, KERNEL_VIRTUAL_MEM_SPACE, LEVEL2_BLOCK_SIZE, NORMAL_MEM, UXN,
+        WRITABLE,
+    },
+    application_manager::initialize_app_manager,
+    console::{flush_terminal, init_terminal},
+    interrupt_handlers::irq::initialize_interrupt_handler,
+    pi3::timer::sleep_s,
+};
 
-static PERIPHERAL_BASE: u32 = 0x3F00_0000;
+static LOGGER: UartLogger = UartLogger;
+static PERIPHERAL_BASE: usize = 0x3F00_0000;
 
 unsafe extern "C" {
-    unsafe static mut __heap_start: u8;
+    unsafe static mut __kernel_end: u8;
-    unsafe static mut __heap_end: u8;
 }
 
 #[global_allocator]
 pub static mut GLOBAL_ALLOCATOR: Heap = Heap::empty();
 
-pub unsafe fn init_heap() {
+pub unsafe fn initialize_kernel_heap() {
-    let start = core::ptr::addr_of_mut!(__heap_start) as usize;
+    let start = core::ptr::addr_of_mut!(__kernel_end) as usize | KERNEL_VIRTUAL_MEM_SPACE;
-    let end = core::ptr::addr_of_mut!(__heap_end) as usize;
+    let size = LEVEL2_BLOCK_SIZE * 2;
 
+    allocate_memory(start, size, PhysSource::Any, NORMAL_MEM | UXN | WRITABLE).unwrap();
     let heap = core::ptr::addr_of_mut!(GLOBAL_ALLOCATOR);
-    (*heap).init(start, end);
+    (*heap).init(start, start + size);
 }
 
 #[panic_handler]
 fn panic(_panic: &PanicInfo) -> ! {
     loop {
-        println!("Panic");
+        println!("Panic: {}", _panic.message());
+        sleep_s(1);
     }
 }
 
@@ -45,9 +57,9 @@ pub mod aarch64;
 pub mod configuration;
 pub mod framebuffer;
 pub mod interrupt_handlers;
-pub mod logger;
-pub mod timer;
 
+pub mod application_manager;
+pub mod console;
 pub mod pi3;
 
 #[inline(always)]
@@ -73,6 +85,33 @@ pub fn get_current_el() -> u64 {
 }
 
 pub fn initialize_kernel() {
-    logger::set_logger(Box::new(DefaultLogger));
+    unsafe { initialize_kernel_heap() };
     initialize_interrupt_handler();
+    initialize_app_manager();
+    init_terminal();
+}
+
+struct UartLogger;
+
+impl log::Log for UartLogger {
+    fn enabled(&self, metadata: &Metadata) -> bool {
+        metadata.level() <= Level::Debug
+    }
+
+    fn log(&self, record: &Record) {
+        if self.enabled(record.metadata()) {
+            println!("{} - {}", record.level(), record.args());
+            if record.level() <= Level::Info {
+                flush_terminal();
+            }
+        }
+    }
+
+    fn flush(&self) {}
+}
+
+pub fn init_logger() {
+    log::set_logger(&LOGGER)
+        .map(|()| log::set_max_level(LevelFilter::Debug))
+        .unwrap();
 }

src/logger.rs

@@ -1,47 +0,0 @@
-use core::fmt::Write;
-
-use alloc::{boxed::Box, fmt};
-
-use crate::peripherals::uart;
-
-static mut LOGGER: Option<Box<dyn Logger>> = None;
-
-pub trait Logger: Write + Sync {
-    fn flush(&mut self);
-}
-
-pub struct DefaultLogger;
-
-impl Logger for DefaultLogger {
-    fn flush(&mut self) {}
-}
-
-impl Write for DefaultLogger {
-    fn write_str(&mut self, s: &str) -> core::fmt::Result {
-        uart::Uart.write_str(s)
-    }
-}
-
-#[macro_export]
-macro_rules! log {
-    () => {};
-    ($($arg:tt)*) => {
-        $crate::logger::log(format_args!($($arg)*))
-    };
-}
-
-pub fn log(args: fmt::Arguments) {
-    unsafe {
-        if let Some(logger) = LOGGER.as_mut() {
-            logger.write_str("\n").unwrap();
-            logger.write_fmt(args).unwrap();
-            logger.flush();
-        }
-    }
-}
-
-pub fn set_logger(logger: Box<dyn Logger>) {
-    unsafe {
-        LOGGER = Some(logger);
-    }
-}

src/main.rs

@@ -1,22 +1,23 @@
 #![no_main]
 #![no_std]
-#![feature(asm_experimental_arch)]
 #![allow(static_mut_refs)]
 #![allow(clippy::missing_safety_doc)]
 use core::{
     arch::{asm, global_asm},
     ptr::write_volatile,
 };
+use log::{debug, info};
 
 extern crate alloc;
 
-use alloc::boxed::Box;
+use alloc::{slice, vec::Vec};
 use nova::{
-    aarch64::registers::{daif, read_id_aa64mmfr0_el1, read_tcr_el1},
+    aarch64::registers::{daif, read_id_aa64mmfr0_el1},
+    application_manager::{add_app, Application},
+    configuration::memory_mapping::initialize_mmu_translation_tables,
     framebuffer::{FrameBuffer, BLUE, GREEN, RED},
-    get_current_el, init_heap,
+    get_current_el, init_logger,
-    interrupt_handlers::{enable_irq_source, IRQSource},
+    interrupt_handlers::irq::{enable_irq_source, IRQSource},
-    log,
     peripherals::{
         gpio::{
             blink_gpio, gpio_pull_up, set_falling_edge_detect, set_gpio_function, GPIOFunction,
@@ -24,15 +25,18 @@ use nova::{
         },
         uart::uart_init,
     },
-    pi3::mailbox,
+    pi3::timer::sleep_s,
-    println,
+    print, println,
 };
 
 global_asm!(include_str!("vector.S"));
+global_asm!(include_str!("config.S"));
+
+static mut FRAMEBUFFER: Option<FrameBuffer> = None;
 
 extern "C" {
     fn el2_to_el1();
-    fn el1_to_el0();
+    fn configure_mmu_el1();
     static mut __bss_start: u32;
     static mut __bss_end: u32;
 }
@@ -58,15 +62,23 @@ pub extern "C" fn main() -> ! {
 
     // Set ACT Led to Outout
     let _ = set_gpio_function(21, GPIOFunction::Output);
+    init_logger();
 
-    println!("Hello World!");
+    info!("Hello World!");
-    println!("Exception level: {}", get_current_el());
+    info!("Current exception level: {}", get_current_el());
+
+    info!("initializing MMU...");
+    initialize_mmu_translation_tables();
+    unsafe { configure_mmu_el1() };
+    info!("MMU configured!");
+
+    debug!("Register: AA64MMFR0_EL1: {:064b}", read_id_aa64mmfr0_el1());
+    info!("Moving El2->EL1");
+    unsafe { FRAMEBUFFER = Some(FrameBuffer::default()) };
 
     unsafe {
-        asm!("mrs x0, SCTLR_EL1",);
         el2_to_el1();
     }
-
     #[allow(clippy::empty_loop)]
     loop {}
 }
@@ -80,26 +92,50 @@ unsafe fn zero_bss() {
 }
 
 #[no_mangle]
-pub extern "C" fn kernel_main() -> ! {
+pub extern "C" fn kernel_main() {
     nova::initialize_kernel();
-    println!("Kernel Main");
+    info!("Kernel Initialized...");
-    println!("Exception Level: {}", get_current_el());
+    info!("Current exception Level: {}", get_current_el());
+
+    let mut test_vector = Vec::new();
+    for i in 0..20 {
+        test_vector.push(i);
+    }
+    debug!("heap allocation test: {:?}", test_vector);
+    enable_irq_source(IRQSource::UartInt);
+
+    let app = Application::new(el0 as *const () as usize);
+    add_app(app).unwrap();
+
+    kernel_loop();
+}
+#[no_mangle]
+pub extern "C" fn kernel_loop() {
     daif::unmask_all();
-
-    unsafe {
-        init_heap();
-        println!("{:b}", read_id_aa64mmfr0_el1());
-        println!("{:b}", read_tcr_el1());
-        el1_to_el0();
-    };
-
     #[allow(clippy::empty_loop)]
     loop {}
 }
-
 #[no_mangle]
-pub extern "C" fn el0() -> ! {
+pub unsafe extern "C" fn el0(argc: usize, argv: *const *const u8) {
     println!("Jumped into EL0");
+    println!("num: {}", argc);
+    println!("argv: {:?}", argv);
+
+    let raw_args = unsafe { slice::from_raw_parts(argv, argc) };
+    let first_arg = raw_args
+        .iter()
+        .map(|&arg_ptr| {
+            if arg_ptr.is_null() {
+                return "";
+            }
+
+            let c_str = unsafe { core::ffi::CStr::from_ptr(arg_ptr) };
+            let str_slice = c_str.to_str().unwrap();
+            str_slice
+        })
+        .next();
+
+    sleep_s(1);
 
     // Set GPIO 26 to Input
     enable_irq_source(IRQSource::GpioInt0); //26 is on the first GPIO bank
@@ -107,27 +143,45 @@ pub extern "C" fn el0() -> ! {
     gpio_pull_up(26);
     set_falling_edge_detect(26, true);
 
-    enable_irq_source(IRQSource::UartInt);
+    if let Some(fb) = unsafe { FRAMEBUFFER.as_mut() } {
-
+        for i in 0..1080 {
-    let fb = FrameBuffer::default();
+            fb.draw_pixel(50, i, BLUE);
-
+        }
         fb.draw_square(500, 500, 600, 700, RED);
         fb.draw_square_fill(800, 800, 900, 900, GREEN);
         fb.draw_square_fill(1000, 800, 1200, 700, BLUE);
         fb.draw_square_fill(900, 100, 800, 150, RED | BLUE);
         fb.draw_string("Hello World! :D\nTest next Line", 500, 5, 3, BLUE);
 
-    fb.draw_function(cos, 100, 101, RED);
+        fb.draw_function(cos, 0, 101, RED);
+    }
 
-    loop {
+    let _temp = syscall(67);
-        let temp = mailbox::read_soc_temp([0]).unwrap();
+
-        log!("{} °C", temp[1] / 1000);
+    if let Some(num) = first_arg.and_then(|val| val.parse::<usize>().ok()) {
+        println!("Calculting prime to: {}", num);
+
+        for i in 3..num {
+            let mut is_prime = true;
+            for j in 3..i {
+                if i == j {
+                    continue;
+                }
+                if i % j == 0 {
+                    is_prime = false;
+                }
+            }
+            if is_prime {
+                print!("{} ", i);
+            }
+        }
+        println!("");
+    } else {
+        println!("Input NaN");
+    }
 
     blink_gpio(SpecificGpio::OnboardLed as u8, 500);
-
+    syscall(0);
-        let b = Box::new([1, 2, 3, 4]);
-        log!("{:?}", b);
-    }
 }
 
 fn cos(x: u32) -> f64 {
@@ -140,3 +194,17 @@ fn enable_uart() {
     let _ = set_gpio_function(15, GPIOFunction::Alternative0);
     uart_init();
 }
+
+pub fn syscall(nr: u64) -> u64 {
+    let ret: u64;
+
+    unsafe {
+        asm!(
+            "svc #0",
+            in("x8") nr,
+            lateout("x0") ret,
+        );
+    }
+
+    ret
+}

src/peripherals/gpio.rs

@@ -2,7 +2,7 @@ use core::result::Result;
 use core::result::Result::Ok;
 use core::sync::atomic::{compiler_fence, Ordering};
 
-use crate::timer::{delay_nops, sleep_ms};
+use crate::pi3::timer::{delay_nops, sleep_ms};
 use crate::{read_address, write_address};
 
 const GPFSEL_BASE: u32 = 0x3F20_0000;

src/peripherals/uart.rs

@@ -118,11 +118,13 @@ fn uart_fifo_enable(enable: bool) {
     unsafe { write_address(UART0_LCRH, lcrh) };
 }
 
+#[inline(always)]
 fn uart_enable_rx_interrupt() {
     unsafe { write_address(UART0_IMSC, UART0_IMSC_RXIM) };
 }
 
 /// Set UART word length and set FIFO status
+#[inline(always)]
 fn uart_set_lcrh(wlen: u32, enable_fifo: bool) {
     let mut value = (wlen & 0b11) << 5;
     if enable_fifo {
@@ -131,10 +133,12 @@ fn uart_set_lcrh(wlen: u32, enable_fifo: bool) {
     unsafe { write_address(UART0_LCRH, value) };
 }
 
+#[inline(always)]
 pub fn read_uart_data() -> char {
     (unsafe { read_address(UART0_DR) } & 0xFF) as u8 as char
 }
 
+#[inline(always)]
 pub fn clear_uart_interrupt_state() {
     unsafe {
         write_address(UART0_ICR, 1 << 4);

src/pi3/mailbox.rs

@@ -1,4 +1,9 @@
-use crate::{read_address, write_address};
+use core::slice;
+
+use crate::{
+    aarch64::mmu::GRANULARITY, configuration::memory_mapping::MAILBOX_PHYSICAL_ADDRESS,
+    configuration::memory_mapping::MAILBOX_VIRTUAL_ADDRESS, read_address, write_address,
+};
 use nova_error::NovaError;
 
 const MBOX_BASE: u32 = 0x3F00_0000 + 0xB880;
@@ -31,8 +36,9 @@ macro_rules! mailbox_command {
         pub fn $name(
             request_data: [u32; $request_len / 4],
         ) -> Result<[u32; $response_len / 4], NovaError> {
-            let mut mailbox =
+            let mailbox = unsafe {
-                [0u32; (HEADER_LENGTH + max!($request_len, $response_len) + FOOTER_LENGTH) / 4];
+                slice::from_raw_parts_mut(MAILBOX_VIRTUAL_ADDRESS as *mut u32, GRANULARITY / 4)
+            };
             mailbox[0] = (HEADER_LENGTH + max!($request_len, $response_len) + FOOTER_LENGTH) as u32; // Total length in Bytes
             mailbox[1] = 0; // Request
             mailbox[2] = $tag; // Command Tag
@@ -42,9 +48,9 @@ macro_rules! mailbox_command {
             mailbox[5..(5 + ($request_len / 4))].copy_from_slice(&request_data);
             mailbox[(5 + ($request_len / 4))..].fill(0);
 
-            let addr = core::ptr::addr_of!(mailbox[0]) as u32;
+            //let addr = core::ptr::addr_of!(mailbox[0]) as u32;
 
-            write_mailbox(8, addr);
+            write_mailbox(8, unsafe { MAILBOX_PHYSICAL_ADDRESS.unwrap() } as u32);
 
             let _ = read_mailbox(8);
 

src/pi3/mod.rs

@@ -1,2 +1,3 @@
 pub mod mailbox;
 pub mod power_management;
+pub mod timer;

src/pi3/power_management.rs

@@ -3,7 +3,7 @@ use core::ptr::{read_volatile, write_volatile};
 use crate::PERIPHERAL_BASE;
 
 /// Power Management Base
-static PM_BASE: u32 = PERIPHERAL_BASE + 0x10_0000;
+static PM_BASE: u32 = PERIPHERAL_BASE as u32 + 0x10_0000;
 static PM_RSTC: u32 = PM_BASE + 0x1c;
 static PM_WDOG: u32 = PM_BASE + 0x24;
 
@@ -23,5 +23,6 @@ pub fn reboot_system() {
             PM_PASSWORD | (pm_rstc_val & PM_RSTC_WRCFG_CLR) | PM_RSTC_WRCFG_FULL_RESET,
         );
     }
+    #[allow(clippy::empty_loop)]
     loop {}
 }

src/terminal.rs

@@ -1,53 +0,0 @@
-use core::fmt::Write;
-
-use alloc::string::String;
-use nova::{
-    interrupt_handlers::register_interrupt_handler, logger::Logger,
-    peripherals::uart::read_uart_data, print, println,
-};
-
-pub struct Terminal {
-    buffer: String,
-    input: String,
-}
-
-impl Terminal {
-    pub fn new() -> Self {
-        Self {
-            buffer: String::new(),
-            input: String::new(),
-        }
-    }
-
-    fn flush(&mut self) {
-        println!("{}", self.buffer);
-        print!("> {}", self.input);
-        self.buffer.clear();
-    }
-}
-
-impl Write for Terminal {
-    fn write_str(&mut self, s: &str) -> core::fmt::Result {
-        self.buffer.push_str(s);
-        Ok(())
-    }
-}
-
-impl Logger for Terminal {
-    fn flush(&mut self) {
-        println!("{}", self.buffer);
-        print!("> {}", self.input);
-        self.buffer.clear();
-    }
-}
-
-fn terminal_uart_rx_interrupt_handler() {
-    print!("{}", read_uart_data());
-}
-
-pub fn register_terminal_interrupt_handler() {
-    register_interrupt_handler(
-        nova::interrupt_handlers::IRQSource::UartInt,
-        terminal_uart_rx_interrupt_handler,
-    );
-}

src/vector.S

@@ -1,5 +1,4 @@
-
+.section .vector_t  , "ax"
-.global vector_table
 .extern irq_handler
 
 .macro    ventry    label
@@ -7,77 +6,31 @@
 b    \label
 .endm
 
-.section .vector_table, "ax"
+.global vector_table
 vector_table:
+    // Exceptions from current EL using SP_EL0
     ventry .
     ventry .
     ventry .
     ventry .
 
+    // Exceptions from the current EL using SP_ELx
     ventry synchronous_interrupt_no_el_change       // Synchronous Exception  0x200
     ventry irq_handler                              // IRQ(Interrupt Request) 0x280
+    ventry .                                        // FIQ(Fast Interrupt Request) 0x300
+    ventry .                                        // SError 0x580
+
+    // Exceptions from lower EL AArch64
+    ventry synchronous_interrupt_imm_lower_aarch64  // Synchronous Exception 0x400
+    ventry irq_handler                              // IRQ(Interrupt Request) 0x480
+    ventry .                                        //  FIQ(Fast Interrupt Request) 0x500
+    ventry .                                        // SError 0x580
+
+    // Exceptions from lower EL AArch32
+    ventry .
+    ventry .
     ventry .
     ventry .
-
-    ventry synchronous_interrupt_imm_lower_aarch64
-    ventry irq_handler
-
-
-.align 4
-.global el2_to_el1
-el2_to_el1:
-
-    mov x0, #(1 << 31)
-    msr HCR_EL2, x0
-
-    // Set SPSR_EL2: return to EL1h
-    mov x0, #(0b0101)
-    msr SPSR_EL2, x0
-
-    // Set return address to kernel_main
-    ldr x0, =kernel_main
-    msr ELR_EL2, x0
-
-    // Set SP_EL1 to stack base
-    ldr x0, =__stack_end
-    msr SP_EL1, x0
-
-    // Set VBAR_EL1 to vector table
-    adr x0, vector_table
-    msr VBAR_EL1, x0
-
-    // Disable MMU
-    ldr x0, =SCTLR_EL1_CONF
-    msr sctlr_el1, x0
-
-    // SIMD should not be trapped
-    mrs x0, CPACR_EL1
-    mov x1, #(0b11<<20)
-    orr x0,x0, x1
-    msr CPACR_EL1,x0
-
-    // Return to EL1
-    eret
-
-.align 4
-.global el1_to_el0
-el1_to_el0:
-
-    // Set SPSR_EL1: return to EL0t
-    mov x0, #(0b0000)
-    msr SPSR_EL1, x0
-
-    // Set return address to el0
-    ldr x0, =el0
-    msr ELR_EL1, x0
-
-    // Set SP_EL1 to stack base
-    ldr x0, =__stack_end_el0
-    msr SP_EL0, x0
-
-    // Return to EL0
-    eret
-
 
 .align 4
 irq_handler:
@@ -126,7 +79,9 @@ synchronous_interrupt_imm_lower_aarch64:
     stp x18, x29, [sp, #144]
     stp x30, xzr, [sp, #160]
 
+    mov x0, sp
     bl rust_synchronous_interrupt_imm_lower_aarch64
+    str x0, [sp, #0]
 
     ldp x0, x1, [sp, #0]
     ldp x2, x3, [sp, #16]
@@ -158,7 +113,9 @@ synchronous_interrupt_no_el_change:
     stp x18, x29, [sp, #144]
     stp x30, xzr, [sp, #160]
 
+    mov x0, sp
     bl rust_synchronous_interrupt_no_el_change
+    str x0, [sp, #0]
 
     ldp x0, x1, [sp, #0]
     ldp x2, x3, [sp, #16]

tools/start_simulator.sh

@@ -1,3 +1,5 @@
+set -e
+
 cargo build --target aarch64-unknown-none --release
 cd "$(dirname "$0")"
 

tools/start_simulator_debug.sh

@@ -1,3 +1,5 @@
+set -e
+
 cargo build --target aarch64-unknown-none
 
 cd "$(dirname "$0")"
@@ -9,6 +11,4 @@ qemu-system-aarch64 \
   -cpu cortex-a53 \
   -serial stdio \
   -sd ../sd.img \
-  -display none \
+  -kernel ../target/aarch64-unknown-none/debug/kernel8.img -S -s
-  -kernel ../target/aarch64-unknown-none/debug/kernel8.img \
-  -s -S

workspace/heap/src/lib.rs

@@ -39,6 +39,10 @@ impl Heap {
         }
     }
 
+    pub fn size(self) -> usize {
+        self.raw_size
+    }
+
     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;

workspace/heap/src/tests.rs

@@ -29,7 +29,7 @@ fn test_heap_allocation() {
         assert_eq!(actual_alloc_size % MIN_BLOCK_SIZE, 0);
 
         // Verify section is occupied
-        assert!((*malloc_header).free == false);
+        assert!(!(*malloc_header).free);
 
         // Verify next header has been created
         let next = (*malloc_header).next.unwrap();
@@ -55,7 +55,7 @@ fn test_full_heap() {
     let malloc = heap.malloc(malloc_size).unwrap();
     let malloc_header = Heap::get_header_ref_from_data_pointer(malloc);
     unsafe {
-        assert_eq!((*malloc_header).free, false);
+        assert!(!(*malloc_header).free);
         assert!((*malloc_header).next.is_none());
     }
 
@@ -79,7 +79,7 @@ fn test_freeing_root() {
     let malloc = heap.malloc(malloc_size).unwrap();
     let malloc_header = Heap::get_header_ref_from_data_pointer(malloc);
     unsafe {
-        assert_eq!((*malloc_header).free, false);
+        assert!(!(*malloc_header).free);
         assert!((*malloc_header).size >= malloc_size);
         assert!((*root_header).next.is_some());
 
@@ -100,7 +100,7 @@ fn test_merging_free_sections() {
     );
 
     let root_header = heap.start_address;
-    let root_header_start_size = unsafe { (*root_header).size };
+    let _root_header_start_size = unsafe { (*root_header).size };
 
     let malloc1 = heap.malloc(MIN_BLOCK_SIZE).unwrap();
     let malloc_header_before = unsafe { *Heap::get_header_ref_from_data_pointer(malloc1) };
@@ -135,14 +135,13 @@ fn test_first_fit() {
     );
 
     let root_header = heap.start_address;
-    let root_header_start_size = unsafe { (*root_header).size };
+    let _root_header_start_size = unsafe { (*root_header).size };
 
     let malloc1 = heap.malloc(MIN_BLOCK_SIZE).unwrap();
-    let malloc2 = heap.malloc(MIN_BLOCK_SIZE).unwrap();
+    let _malloc2 = heap.malloc(MIN_BLOCK_SIZE).unwrap();
     let malloc3 = heap.malloc(MIN_BLOCK_SIZE * 3).unwrap();
     let malloc4 = heap.malloc(MIN_BLOCK_SIZE).unwrap();
 
-    unsafe {
     assert!(heap.free(malloc1).is_ok());
     assert!(heap.free(malloc3).is_ok());
     let malloc5 = heap.malloc(MIN_BLOCK_SIZE * 2).unwrap();
@@ -162,4 +161,3 @@ fn test_first_fit() {
     let malloc7 = heap.malloc(MIN_BLOCK_SIZE).unwrap();
     assert_eq!(malloc1, malloc7);
 }
-}

workspace/nova_error/src/lib.rs

@@ -5,7 +5,12 @@ use core::prelude::rust_2024::derive;
 
 #[derive(Debug)]
 pub enum NovaError {
+    General(&'static str),
     Mailbox,
     HeapFull,
     EmptyHeapSegmentNotAllowed,
+    Misalignment,
+    InvalidGranularity,
+    Paging(&'static str),
+    OutOfMeomory,
 }