76 lines
2.3 KiB
Rust
76 lines
2.3 KiB
Rust
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use crate::{bootinfo::BOOTINFO, println, virtual_memory::AsVirt};
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use bootloader::boot_info::MemoryRegionKind;
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use core::mem;
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use spin::{Lazy, Mutex};
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use tap::Tap;
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use x86_64::{
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structures::paging::{FrameAllocator, FrameDeallocator, PhysFrame, Size4KiB},
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PhysAddr,
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};
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type FrameIterator = impl Iterator<Item = PhysFrame>;
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#[derive(Default)]
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struct FrameStack(Option<(&'static mut FrameStack, PhysFrame)>);
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pub struct FrameManager {
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stack: FrameStack,
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iter: FrameIterator,
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}
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unsafe impl FrameAllocator<Size4KiB> for FrameManager {
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fn allocate_frame(&mut self) -> Option<PhysFrame> {
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self.iter.next().or_else(|| self.stack.pop())
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}
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}
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impl FrameStack {
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/// # Safety
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/// The frame must be unique
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unsafe fn push(&mut self, frame: PhysFrame) {
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self.0 = Some((
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unsafe { &mut *frame.as_virt_ptr::<Self>().tap_mut(|x| x.write(mem::take(self))) },
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frame,
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));
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}
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fn pop(&mut self) -> Option<PhysFrame> {
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let (head, frame) = self.0.take()?;
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*self = mem::take(head);
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Some(frame)
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}
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}
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impl FrameDeallocator<Size4KiB> for FrameManager {
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unsafe fn deallocate_frame(&mut self, frame: PhysFrame) {
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unsafe { self.stack.push(frame) }
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}
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}
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pub static PHYSICAL_MEMORY: Lazy<Mutex<FrameManager>> = Lazy::new(|| {
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let region_iter =
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BOOTINFO.memory_regions.iter().filter(|region| region.kind == MemoryRegionKind::Usable);
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let frame_iter = region_iter
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.clone()
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.flat_map(|region| {
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((region.start >> 12) + if region.start & 0xFFF > 0 { 1 } else { 0 })
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..(region.end >> 12)
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})
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.map(|num| PhysFrame::from_start_address(PhysAddr::new(num << 12)).unwrap());
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#[allow(clippy::cast_precision_loss)]
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let mut mem_size = region_iter
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.map(|region| {
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4096 * ((region.end >> 12)
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- ((region.start >> 12) + if region.start & 0xFFF > 0 { 1 } else { 0 }))
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})
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.sum::<u64>() as f64;
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let mut prefix = 0;
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while mem_size >= 1024.0 {
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mem_size /= 1024.0;
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prefix += 1;
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}
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let prefix = ["", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei"][prefix];
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println!("[PMM] Initialized, found {:.2} {}B of memory", mem_size, prefix);
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Mutex::new(FrameManager { stack: FrameStack(None), iter: frame_iter })
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});
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