hermit/arch/x86_64/mm/
mod.rs

1pub(crate) mod paging;
2pub(crate) mod physicalmem;
3pub(crate) mod virtualmem;
4
5use memory_addresses::arch::x86_64::{PhysAddr, VirtAddr};
6#[cfg(feature = "common-os")]
7use x86_64::structures::paging::{PageSize, Size4KiB as BasePageSize};
8
9pub use self::paging::init_page_tables;
10#[cfg(feature = "common-os")]
11use crate::arch::mm::paging::{PageTableEntryFlags, PageTableEntryFlagsExt};
12
13#[cfg(feature = "common-os")]
14pub fn create_new_root_page_table() -> usize {
15	use x86_64::registers::control::Cr3;
16
17	let physaddr =
18		physicalmem::allocate_aligned(BasePageSize::SIZE as usize, BasePageSize::SIZE as usize)
19			.unwrap();
20	let virtaddr =
21		virtualmem::allocate_aligned(2 * BasePageSize::SIZE as usize, BasePageSize::SIZE as usize)
22			.unwrap();
23	let mut flags = PageTableEntryFlags::empty();
24	flags.normal().writable();
25
26	let entry: u64 = unsafe {
27		let (frame, _flags) = Cr3::read();
28		paging::map::<BasePageSize>(virtaddr, frame.start_address().into(), 1, flags);
29		let entry: &u64 = &*virtaddr.as_ptr();
30
31		*entry
32	};
33
34	let slice_addr = virtaddr + BasePageSize::SIZE;
35	paging::map::<BasePageSize>(slice_addr, physaddr, 1, flags);
36
37	unsafe {
38		let pml4 = core::slice::from_raw_parts_mut(slice_addr.as_mut_ptr(), 512);
39
40		// clear PML4
41		for elem in pml4.iter_mut() {
42			*elem = 0;
43		}
44
45		// copy first element and the self reference
46		pml4[0] = entry;
47		// create self reference
48		pml4[511] = physaddr.as_u64() + 0x3; // PG_PRESENT | PG_RW
49	};
50
51	paging::unmap::<BasePageSize>(virtaddr, 2);
52	virtualmem::deallocate(virtaddr, 2 * BasePageSize::SIZE as usize);
53
54	physaddr.as_usize()
55}
56
57pub fn init() {
58	paging::init();
59	physicalmem::init();
60	virtualmem::init();
61
62	#[cfg(feature = "common-os")]
63	{
64		use x86_64::registers::control::Cr3;
65
66		let (frame, _flags) = Cr3::read();
67		crate::scheduler::BOOT_ROOT_PAGE_TABLE
68			.set(frame.start_address().as_u64().try_into().unwrap())
69			.unwrap();
70	}
71}
hermit/arch/x86_64/mm/mod.rs

hermit/arch/x86_64/mm/
mod.rs
