forked from AbleOS/ableos
63 lines
1.8 KiB
Rust
63 lines
1.8 KiB
Rust
use limine::{LimineMemmapResponse, LimineMemoryMapEntryType};
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use x86_64::{
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structures::paging::{
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FrameAllocator, FrameDeallocator, OffsetPageTable, PageTable, PhysFrame,
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Size4KiB,
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},
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PhysAddr, VirtAddr,
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};
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pub unsafe fn init(physical_memory_offset: VirtAddr) -> OffsetPageTable<'static> {
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let level_4_table = active_level_4_table(physical_memory_offset);
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OffsetPageTable::new(level_4_table, physical_memory_offset)
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}
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unsafe fn active_level_4_table(physical_memory_offset: VirtAddr) -> &'static mut PageTable {
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use x86_64::registers::control::Cr3;
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let (level_4_table_frame, _) = Cr3::read();
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let phys = level_4_table_frame.start_address();
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let virt = physical_memory_offset + phys.as_u64();
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let page_table_ptr: *mut PageTable = virt.as_mut_ptr();
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// THIS IS UNSAFE
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&mut *page_table_ptr
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}
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pub struct BootInfoFrameAllocator {
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memory_map: &'static LimineMemmapResponse,
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next: usize,
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}
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impl BootInfoFrameAllocator {
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pub unsafe fn init(memory_map: &'static LimineMemmapResponse) -> Self {
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Self {
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memory_map,
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next: 0,
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}
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}
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fn usable_frames(&self) -> impl Iterator<Item = PhysFrame> {
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self.memory_map.mmap().unwrap().iter()
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.filter(|r| r.typ == LimineMemoryMapEntryType::Usable)
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.map(|r| r.base..r.base + r.len)
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.flat_map(|r| r.step_by(4096))
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.map(|addr| PhysFrame::containing_address(PhysAddr::new(addr)))
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}
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}
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unsafe impl FrameAllocator<Size4KiB> for BootInfoFrameAllocator {
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fn allocate_frame(&mut self) -> Option<PhysFrame<Size4KiB>> {
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let frame = self.usable_frames().nth(self.next);
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self.next += 1;
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frame
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}
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}
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impl FrameDeallocator<Size4KiB> for BootInfoFrameAllocator {
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unsafe fn deallocate_frame(&mut self, _frame: PhysFrame<Size4KiB>) {
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// TODO
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}
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}
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