Add page fault handler that does nothing, I am tired

kernel/src/arch/x86_64/memmap.rs

@@ -0,0 +1,56 @@
+//! Sets up a memory map using Limine.
+
+use limine::{
+    request::{HhdmRequest, KernelAddressRequest, MemoryMapRequest},
+    response::MemoryMapResponse,
+};
+use spin::Lazy;
+
+#[used]
+#[link_section = ".requests"]
+static MEMORY_MAP_REQUEST: MemoryMapRequest = MemoryMapRequest::new();
+
+#[used]
+#[link_section = ".requests"]
+static HIGHER_HALF_DIRECT_MAP_REQUEST: HhdmRequest = HhdmRequest::new();
+
+/// ```rs
+/// let virt_addr = phys_addr + offset;
+/// let phys_addr = virt_addr - offset; // (given VA is in the HHDM). Do not use for executable code.
+/// ```
+pub static PHYSICAL_MEMORY_OFFSET: Lazy<u64> = Lazy::new(|| {
+    HIGHER_HALF_DIRECT_MAP_REQUEST
+        .get_response()
+        .unwrap()
+        .offset()
+});
+
+#[used]
+#[link_section = ".requests"]
+static KERNEL_ADDRESS_REQUEST: KernelAddressRequest = KernelAddressRequest::new();
+
+/// Converts virtual addresses in the kernel to a physical address like this:
+/// ```rs
+/// let phys_addr = virt_addr - virtual_base + physical_base;
+/// ```
+///
+/// Returns (virtual_base, physical_base)
+pub static KERNEL_PHYSICAL_MEMORY_OFFSET: Lazy<(u64, u64)> = Lazy::new(|| {
+    let resp = KERNEL_ADDRESS_REQUEST.get_response().unwrap();
+
+    // These are base addresses, using Limine's built in page table.
+    (resp.virtual_base(), resp.physical_base())
+});
+
+/// Fetches the memory map from Limine.
+///
+/// # Panics
+///
+/// Panics if the memory map was not found in MEMORY_MAP_REQUEST.
+pub fn get_memory_map() -> &'static MemoryMapResponse {
+    if let Some(memory_map) = MEMORY_MAP_REQUEST.get_response() {
+        return memory_map;
+    } else {
+        unreachable!("Could not fetch memory map from Limine.")
+    }
+}