paging done, starting on allocation.

.cargo/config.toml

@@ -3,7 +3,7 @@ target = "x86_64-kernel"
 target-dir = "build/target"
 
 [unstable]
-build-std = ["core", "compiler_builtins"]
+build-std = ["core", "compiler_builtins", "alloc"]
 build-std-features = ["compiler-builtins-mem"]
 
 [env]

.gitmodules

@@ -10,3 +10,6 @@
 [submodule "lib/lib_serial"]
 	path = lib/lib_serial
 	url = https://git.zxq5.dev/OsDev/FoundryOS-lib_serial.git
+[submodule "lib/lib_alloc"]
+	path = lib/lib_alloc
+	url = https://git.zxq5.dev/OsDev/FoundryOS-lib_alloc.git

Cargo.lock

@@ -34,6 +34,7 @@ name = "foundry_os"
 version = "0.1.0"
 dependencies = [
  "cc",
+ "lib_alloc",
  "lib_ascii",
  "lib_framebuffer",
  "lib_serial",
@@ -53,6 +54,10 @@ dependencies = [
  "spin",
 ]
 
+[[package]]
+name = "lib_alloc"
+version = "0.1.0"
+
 [[package]]
 name = "lib_application"
 version = "0.1.0"

Cargo.toml

@@ -5,6 +5,7 @@ members = [
     "lib/lib_ascii",
     "kernel",
     "lib/lib_application", 
+    "lib/lib_alloc",
 ]
 resolver = "2"
 

kernel/Cargo.toml

@@ -8,6 +8,7 @@ limine = "0.3.1"
 lib_framebuffer = { path = "../lib/lib_framebuffer" }
 lib_serial = { path = "../lib/lib_serial" }
 lib_ascii = { path = "../lib/lib_ascii" }
+lib_alloc = { path = "../lib/lib_alloc" }
 x86_64 = "0.15.2"
 spin = "0.9.8"
 pic8259 = "0.11.0"

kernel/src/arch/x86_64/memory.rs

@@ -0,0 +1,137 @@
+use lib_alloc::allocator::FoundryAllocator;
+use limine::{memory_map::EntryType, response::MemoryMapResponse};
+use x86_64::{
+    addr,
+    registers::control::Cr3,
+    structures::paging::{
+        page_table::FrameError, FrameAllocator, OffsetPageTable, PageTable, PhysFrame, Size4KiB,
+    },
+    PhysAddr, VirtAddr,
+};
+
+#[global_allocator]
+static ALLOCATOR: FoundryAllocator = FoundryAllocator;
+
+/// Returns a mutable reference to the current level 4 page table.
+///
+/// # Safety
+///
+/// The caller must ensure that the level 4 page table is not modified
+/// simultaneously. The caller must also ensure that the physical memory offset
+/// is correct, to ensure that the correct virtual address is constructed.
+unsafe fn active_l4_table(physical_memory_offset: VirtAddr) -> &'static mut PageTable {
+    let (level_4_frame, _) = Cr3::read();
+
+    let phys_addr = level_4_frame.start_address();
+    let virt = phys_addr.as_u64() + physical_memory_offset.as_u64();
+    &mut *(virt as *mut PageTable)
+}
+
+/// Initializes the `OffsetPageTable` for the current CPU architecture.
+///
+/// # Safety
+///
+/// This function must be called only once and should be called before any
+/// memory operations are performed that rely on virtual memory management.
+/// The provided `physical_memory_offset` must be accurate to ensure correct
+/// translation of physical addresses.
+///
+/// # Parameters
+///
+/// - `physical_memory_offset`: The offset to convert physical addresses to
+///   virtual addresses in the higher-half direct map.
+///
+/// # Returns
+///
+/// Returns an `OffsetPageTable` that allows for manipulation of the page
+/// tables for the current CPU architecture.
+pub unsafe fn init(physical_memory_offset: VirtAddr) -> OffsetPageTable<'static> {
+    let l4_table = active_l4_table(physical_memory_offset);
+    OffsetPageTable::new(l4_table, physical_memory_offset)
+}
+
+pub(crate) struct FoundryOSFrameAllocator {
+    memory_map: &'static MemoryMapResponse,
+    next: usize,
+}
+
+impl FoundryOSFrameAllocator {
+    /// Creates a new `FoundryOSFrameAllocator` from a memory map.
+    ///
+    /// This function takes a reference to a `MemoryMapResponse` and initializes a
+    /// `FoundryOSFrameAllocator` with it. The `next` field is set to 0, indicating that
+    /// the first frame to be allocated is the first frame in the memory map.
+    pub unsafe fn init(memory_map: &'static MemoryMapResponse) -> FoundryOSFrameAllocator {
+        FoundryOSFrameAllocator {
+            memory_map,
+            next: 0,
+        }
+    }
+
+    /// An iterator over all usable frames in the memory map.
+    ///
+    /// Yields one `PhysFrame` for each available 4KiB frame in the memory map.
+    ///
+    /// This function is used to allocate frames for the pagemap.
+    fn usable_frames(&self) -> impl Iterator<Item = PhysFrame> {
+        let regions = self.memory_map.entries().iter();
+        let usable_regions = regions.filter(|region| region.entry_type == EntryType::USABLE);
+
+        let addr_ranges = usable_regions.map(|region| region.base..region.base + region.length);
+
+        let frame_addresses = addr_ranges.flat_map(|r| r.step_by(4096));
+
+        frame_addresses.map(|addr| PhysFrame::from_start_address(PhysAddr::new(addr)).unwrap())
+    }
+}
+
+unsafe impl FrameAllocator<Size4KiB> for FoundryOSFrameAllocator {
+    /// Allocates a frame from the list of usable frames.
+    ///
+    /// This function returns the next available `PhysFrame` from the memory map,
+    /// if one exists. Once a frame is allocated, the internal counter is incremented
+    /// to point to the next frame for future allocations.
+    ///
+    /// # Returns
+    ///
+    /// - `Some(PhysFrame)`: If a usable frame is available.
+    /// - `None`: If there are no more usable frames to allocate.
+
+    fn allocate_frame(&mut self) -> Option<PhysFrame> {
+        let frame = self.usable_frames().nth(self.next);
+        self.next += 1;
+        frame
+    }
+}
+
+// pub unsafe fn translate_addr(addr: VirtAddr, physical_memory_offset: VirtAddr) -> Option<PhysAddr> {
+//     translate_addr_inner(addr, physical_memory_offset)
+// }
+
+// fn translate_addr_inner(addr: VirtAddr, physical_memory_offset: VirtAddr) -> Option<PhysAddr> {
+//     let (l4_table_frame, _) = Cr3::read();
+
+//     let table_indexes = [
+//         addr.p4_index(),
+//         addr.p3_index(),
+//         addr.p2_index(),
+//         addr.p1_index(),
+//     ];
+//     let mut frame = l4_table_frame;
+
+//     for &i in &table_indexes {
+//         let virt = physical_memory_offset + frame.start_address().as_u64();
+//         let table_ptr: *const PageTable = virt.as_ptr();
+//         let table = unsafe { &*table_ptr };
+
+//         let entry = &table[i];
+
+//         frame = match entry.frame() {
+//             Ok(frame) => frame,
+//             Err(FrameError::FrameNotPresent) => return None,
+//             Err(FrameError::HugeFrame) => panic!("huge frames are not supported!"),
+//         };
+//     }
+
+//     Some(frame.start_address() + u64::from(addr.page_offset()))
+// }

kernel/src/arch/x86_64/mod.rs

@@ -1,3 +1,7 @@
 pub mod gdt;
 
 pub mod interrupts;
+
+pub mod memory;
+
+pub(crate) mod memmap;

kernel/src/lib.rs

@@ -1,12 +1,16 @@
 #![no_std]
 #![feature(abi_x86_interrupt)]
 
+extern crate alloc;
+
 use core::arch::asm;
 use limine::request::{RequestsEndMarker, RequestsStartMarker};
 use limine::BaseRevision;
 
 pub use lib_ascii::{print, print_log, println, println_log, WRITER};
 pub use lib_serial::{serial_print, serial_println, serial_read};
+use x86_64::structures::paging::Translate;
+use x86_64::{PhysAddr, VirtAddr};
 
 mod arch;
 
@@ -28,6 +32,8 @@ static _END_MARKER: RequestsEndMarker = RequestsEndMarker::new();
 
 #[panic_handler]
 fn rust_panic(_info: &core::panic::PanicInfo) -> ! {
+    println!("Kernel panic: {}", _info);
+    serial_println!("Kernel panic: {}", _info);
     hcf();
 }
 
@@ -49,11 +55,19 @@ pub fn boot() -> Result<(), &'static str> {
         return Err("base revision not supported");
     }
 
+    use arch::x86_64::{gdt, interrupts, memmap, memory};
+
+    let memory_map = memmap::get_memory_map();
     lib_serial::init()?;
-    arch::x86_64::gdt::init();
-    arch::x86_64::interrupts::init_idt();
+    gdt::init();
+    interrupts::init_idt();
+
+    let mut frame_allocator = unsafe { memory::FoundryOSFrameAllocator::init(memory_map) };
 
     x86_64::instructions::interrupts::enable();
 
+    let physical_memory_offset = VirtAddr::new(*memmap::PHYSICAL_MEMORY_OFFSET);
+    let l4_table = unsafe { memory::init(physical_memory_offset) };
+
     Ok(())
 }