hermit/mm/
virtualmem.rs

1use core::alloc::AllocError;
2use core::fmt;
3
4use free_list::{FreeList, PageLayout, PageRange};
5use hermit_sync::InterruptTicketMutex;
6use memory_addresses::VirtAddr;
7
8use crate::mm::{PageRangeAllocator, PageRangeBox};
9
10static KERNEL_FREE_LIST: InterruptTicketMutex<FreeList<16>> =
11	InterruptTicketMutex::new(FreeList::new());
12
13pub struct PageAlloc;
14
15impl PageRangeAllocator for PageAlloc {
16	unsafe fn init() {
17		unsafe {
18			init();
19		}
20	}
21
22	fn allocate(layout: PageLayout) -> Result<PageRange, AllocError> {
23		KERNEL_FREE_LIST
24			.lock()
25			.allocate(layout)
26			.map_err(|_| AllocError)
27	}
28
29	fn allocate_at(range: PageRange) -> Result<(), AllocError> {
30		KERNEL_FREE_LIST
31			.lock()
32			.allocate_at(range)
33			.map_err(|_| AllocError)
34	}
35
36	unsafe fn deallocate(range: PageRange) {
37		unsafe {
38			KERNEL_FREE_LIST.lock().deallocate(range).unwrap();
39		}
40	}
41}
42
43impl fmt::Display for PageAlloc {
44	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
45		let free_list = KERNEL_FREE_LIST.lock();
46		write!(f, "PageAlloc free list:\n{free_list}")
47	}
48}
49
50pub type PageBox = PageRangeBox<PageAlloc>;
51
52unsafe fn init() {
53	let range = PageRange::new(
54		kernel_heap_end().as_usize().div_ceil(2),
55		kernel_heap_end().as_usize() + 1,
56	)
57	.unwrap();
58
59	unsafe {
60		PageAlloc::deallocate(range);
61	}
62}
63
64/// End of the virtual memory address space reserved for kernel memory (inclusive).
65/// The virtual memory address space reserved for the task heap starts after this.
66#[inline]
67pub fn kernel_heap_end() -> VirtAddr {
68	cfg_if::cfg_if! {
69		if #[cfg(target_arch = "aarch64")] {
70			// maximum address, which can be supported by TTBR0
71			VirtAddr::new(0xFFFF_FFFF_FFFF)
72		} else if #[cfg(target_arch = "riscv64")] {
73			// 256 GiB
74			VirtAddr::new(0x0040_0000_0000 - 1)
75		} else if #[cfg(target_arch = "x86_64")] {
76			use x86_64::structures::paging::PageTableIndex;
77
78			let p4_index = if cfg!(feature = "common-os") {
79				PageTableIndex::new(1)
80			} else {
81				PageTableIndex::new(256)
82			};
83
84			let addr = u64::from(p4_index) << 39;
85			assert_eq!(VirtAddr::new_truncate(addr).p4_index(), p4_index);
86
87			VirtAddr::new_truncate(addr - 1)
88		}
89	}
90}
hermit/mm/virtualmem.rs

hermit/mm/
virtualmem.rs
