Setup paging

loader/src/main.rs

@@ -7,6 +7,7 @@ use core::panic::PanicInfo;
 
 use elf::load_kernel;
 use log::{error, info};
+use paging::setup_paging;
 use static_alloc::Bump;
 use uefi::{
     entry,
@@ -15,6 +16,7 @@ use uefi::{
 };
 
 mod elf;
+mod paging;
 
 #[global_allocator]
 static A: Bump<[u8; 8 * 1024 * 1024]> = Bump::uninit();
@@ -27,7 +29,8 @@ fn main(image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
     info!("Starting bootloader...");
     uefi::helpers::init(&mut system_table).unwrap();
     load_kernel(KERNEL, &system_table);
-    let _memory_map = system_table.exit_boot_services(MemoryType::LOADER_DATA).1;
+    let memory_map = system_table.exit_boot_services(MemoryType::LOADER_DATA).1;
+    setup_paging(&memory_map);
     loop {}
 }
 #[panic_handler]

loader/src/paging.rs

@@ -0,0 +1,63 @@
+use core::alloc::Layout;
+
+use alloc::alloc::alloc_zeroed;
+use uefi::table::boot::{MemoryMap, MemoryType};
+use x86_64::{
+    registers::control::{Cr3, Cr3Flags},
+    structures::paging::{PageTable, PageTableFlags, PhysFrame},
+    PhysAddr,
+};
+
+fn get_table_entry(table: &mut PageTable, i: usize) -> &mut PageTable {
+    if table[i].is_unused() {
+        let layout = Layout::new::<PageTable>().align_to(0x1000).unwrap();
+        let new_table;
+        unsafe {
+            new_table = alloc_zeroed(layout);
+        }
+        let addr = PhysAddr::new(new_table as u64);
+        table[i].set_addr(addr, PageTableFlags::PRESENT | PageTableFlags::WRITABLE);
+    }
+    let ptr = table[i].addr().as_u64() as *mut PageTable;
+    unsafe {
+        return ptr.as_mut().unwrap();
+    }
+}
+fn map(pml4: &mut PageTable, mut virt: usize, phys: usize) {
+    virt /= 0x1000;
+    let table_i = virt % 512;
+    let directory_i = virt / 512 % 512;
+    let pdpt_i = virt / 512 / 512 % 512;
+    let pml4_i = virt / 512 / 512 / 512 % 512;
+    let pdpt = get_table_entry(pml4, pml4_i);
+    let directory = get_table_entry(pdpt, pdpt_i);
+    let table = get_table_entry(directory, directory_i);
+    let phys_addr = PhysAddr::new(phys as u64);
+    table[table_i].set_addr(phys_addr, PageTableFlags::PRESENT | PageTableFlags::WRITABLE)
+}
+pub fn setup_paging(memory_map: &MemoryMap) {
+    let pml4;
+    let layout = Layout::new::<PageTable>().align_to(0x1000).unwrap();
+    unsafe {
+        pml4 = (alloc_zeroed(layout) as *mut PageTable).as_mut().unwrap();
+    }
+    for i in memory_map.entries() {
+        if i.ty == MemoryType::LOADER_CODE
+            || i.ty == MemoryType::LOADER_DATA
+            || i.ty == MemoryType::RUNTIME_SERVICES_CODE
+            || i.ty == MemoryType::RUNTIME_SERVICES_DATA
+            || i.ty == MemoryType::BOOT_SERVICES_CODE
+            || i.ty == MemoryType::BOOT_SERVICES_DATA
+        {
+            for j in 0..i.page_count {
+                let addr = i.phys_start + j * 0x1000;
+                map(pml4, addr as usize, addr as usize);
+            }
+        }
+    }
+    let pml4_addr = PhysAddr::new(pml4 as *const PageTable as u64);
+    let frame = PhysFrame::from_start_address(pml4_addr).unwrap();
+    unsafe {
+        Cr3::write(frame, Cr3Flags::empty());
+    }
+}