4lDO2
1138 lines
41 KiB
Rust
1138 lines
41 KiB
Rust
//! # Memory management
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//! Some code was borrowed from [Phil Opp's Blog](http://os.phil-opp.com/allocating-frames.html)
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use core::{
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cell::SyncUnsafeCell,
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mem,
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num::NonZeroUsize,
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sync::atomic::{AtomicUsize, Ordering},
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};
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use spin::Mutex;
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use crate::context::{self, memory::{AccessMode, PfError}};
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use crate::kernel_executable_offsets::{__usercopy_start, __usercopy_end};
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use crate::paging::Page;
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pub use crate::paging::{PAGE_SIZE, PAGE_MASK, PhysicalAddress, RmmA, RmmArch};
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use rmm::{
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FrameAllocator,
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FrameCount, VirtualAddress, TableKind, BumpAllocator,
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};
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use crate::syscall::error::{ENOMEM, Error};
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/// A memory map area
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#[derive(Copy, Clone, Debug, Default)]
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#[repr(packed)]
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pub struct MemoryArea {
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pub base_addr: u64,
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pub length: u64,
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pub _type: u32,
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pub acpi: u32,
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}
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/// Get the number of frames available
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pub fn free_frames() -> usize {
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0
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}
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/// Get the number of frames used
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pub fn used_frames() -> usize {
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0
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}
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/// Allocate a range of frames
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pub fn allocate_frames(count: usize) -> Option<Frame> {
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allocate_frames_complex(count, (), None, count).map(|(f, _)| f)
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}
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pub fn allocate_frame() -> Option<Frame> {
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allocate_frames(1)
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}
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pub fn allocate_frames_complex(count: usize, flags: (), strategy: Option<()>, min: usize) -> Option<(Frame, usize)> {
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// TODO: Split into sub-power of two allocations.
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let min_order = min.next_power_of_two().trailing_zeros();
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let _req_order = count.next_power_of_two().trailing_zeros();
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/*if DEBUG.load(Ordering::Relaxed) > 0 {
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log::info!("BEFORE");
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log::info!("PREALLOC 2^{min_order}");
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debug_freelist();
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}*/
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let before = get_freelist_pagecount();
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//debug_freelist();
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let mut freelist = FREELIST.lock();
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let Some((frame_order, frame)) = freelist.iter().enumerate().skip(min_order as usize).find_map(|(i, f)| f.map(|f| (i as u32, f))) else {
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// TODO: For larger sizes than the max order, split into power of two allocations.
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log::error!("COUNT {min}");
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log::error!("FREELIST {freelist:#?}");
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log::error!(":(");
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return None;
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};
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let info = get_page_info(frame)
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.unwrap_or_else(|| panic!("no page info for allocated frame {frame:?}"))
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.as_free().expect("freelist frames must not be marked used!");
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let next_free = info.next();
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//log::info!("FREE {frame:?} ORDER {frame_order} NEXT_FREE {next_free:?}");
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assert_eq!(next_free.order(), frame_order, "{frame:?}->next {next_free:?}.order != {frame_order}");
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if let Some(next) = next_free.frame() {
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let f = get_free_alloc_page_info(next);
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assert_eq!(f.prev().frame(), Some(frame));
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assert_ne!(next, frame);
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assert!(next.is_aligned_to_order(frame_order), "NEXT {next:?} UNALIGNED");
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f.set_prev(P2Frame::new(None, frame_order));
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}
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assert!(frame.is_aligned_to_order(frame_order));
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assert_eq!(next_free.order(), frame_order);
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freelist[frame_order as usize] = next_free.frame();
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// TODO: Is this LIFO cache optimal?
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//log::info!("MIN{min_order}FRAMEORD{frame_order}");
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for order in (min_order..frame_order).rev() {
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//log::info!("SPLIT ORDER {order}");
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let order_page_count = 1 << order;
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let hi = frame.next_by(order_page_count);
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//log::info!("SPLIT INTO {frame:?}:{hi:?} ORDER {order}");
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assert_eq!(freelist[order as usize], None);
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/*if let Some(old_head) = freelist[order as usize].replace(hi) {
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hi_info.set_next(P2Frame::new(Some(old_head), order));
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hi_info.set_prev(P2Frame::new(None, order));
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//
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let _ = get_free_alloc_page_info(hi);
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//
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let old_head_info = get_free_alloc_page_info(old_head);
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assert_eq!(old_head_info.prev().frame(), None);
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old_head_info.set_prev(P2Frame::new(Some(hi), order));
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}*/
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let hi_info = get_page_info(hi).expect("sub-p2frame of split p2flame lacked PageInfo").make_free(order);
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assert!(!hi.is_aligned_to_order(frame_order));
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assert!(hi.is_aligned_to_order(order));
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hi_info.set_next(P2Frame::new(None, order));
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hi_info.set_prev(P2Frame::new(None, order));
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freelist[order as usize] = Some(hi);
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}
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drop(freelist);
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_get_freelist_pagecount(false, min_order, frame_order, true);
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_get_freelist_pagecount(false, min_order, frame_order, false);
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info.mark_used();
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_get_freelist_pagecount(false, min_order, frame_order, false);
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_get_freelist_pagecount(false, min_order, frame_order, true);
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unsafe {
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(RmmA::phys_to_virt(frame.start_address()).data() as *mut u8).write_bytes(0, PAGE_SIZE << min_order);
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}
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assert!(frame.start_address().data() >= unsafe { ALLOCATOR_DATA.abs_off });
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//log::info!("ALLOCATED {frame:?}+2^{min_order}");
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/*unsafe {
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let mut found = false;
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for area in AREAS {
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if frame.start_address() >= area.base && frame.next_by(1 << min_order).start_address() < area.base.add(area.size) {
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found = true;
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break;
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}
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}
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assert!(found);
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}*/
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let after = _get_freelist_pagecount(false, min_order, frame_order, false);
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assert_eq!(after, before - (1 << min_order), "wrong freelist count for order {min_order} fr {frame_order}, before={before}");
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//if DEBUG.load(Ordering::Relaxed) > 0 {
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//log::info!("ALLOCED {frame:?}+2^{min_order}");
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//log::info!("AFTER");
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//debug_freelist();
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//}
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Some((frame, PAGE_SIZE << min_order))
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}
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/// Deallocate a range of frames
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pub unsafe fn deallocate_frames(frame: Frame, count: usize) {
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log::info!("DEALLOC{frame:?}+{count}");
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let before = get_freelist_pagecount();
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debug_freelist();
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deallocate_frames_inner(frame, count);
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debug_freelist();
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//loop {}
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let after = get_freelist_pagecount();
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}
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unsafe fn deallocate_frames_inner(frame: Frame, count: usize) {
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if count == 0 {
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log::warn!("Count == 0 (frame {frame:?}");
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return;
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}
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//log::info!("DEALLOCATE {frame:?}+{count}");
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let max_order = core::cmp::min(MAX_ORDER, count.next_power_of_two().trailing_zeros());
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let (first_aligned, chunk_order, number_of_chunks) = (0..=max_order).rev().find_map(|order| {
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let bytes_for_order = PAGE_SIZE << order;
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let first_aligned = frame.start_address().data().next_multiple_of(bytes_for_order);
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let last_aligned = (frame.start_address().data() + count * PAGE_SIZE) / bytes_for_order * bytes_for_order;
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let chunks = (last_aligned - first_aligned) / bytes_for_order;
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(first_aligned < last_aligned).then_some((first_aligned, order, chunks))
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}).expect("must succeed at least for order=0");
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for i in 0..number_of_chunks {
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let p2frame = Frame::containing_address(PhysicalAddress::new(first_aligned + i * (PAGE_SIZE << chunk_order)));
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//log::info!("P2DEALLOCATE {frame:?}+2^{chunk_order}");
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deallocate_p2frame(p2frame, chunk_order);
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}
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let first_aligned_frame = Frame::containing_address(PhysicalAddress::new(first_aligned));
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let lo_subblock_page_count = first_aligned_frame.offset_from(frame);
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let hi_subblock_page_count = count - (number_of_chunks << chunk_order) - lo_subblock_page_count;
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if lo_subblock_page_count > 0 {
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//log::info!("SUBDEALLOCATE LO {frame:?}+{lo_subblock_page_count}");
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deallocate_frames_inner(frame, lo_subblock_page_count);
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}
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if hi_subblock_page_count > 0 {
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let hi_frame = first_aligned_frame.next_by(number_of_chunks << chunk_order);
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//log::info!("SUBDEALLOCATE HI {hi_frame:?}+{hi_subblock_page_count}");
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deallocate_frames_inner(hi_frame, hi_subblock_page_count);
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}
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}
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fn get_freelist_pagecount() -> usize {
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_get_freelist_pagecount(false, 100, 100, false)
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}
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pub static DEBUG: AtomicUsize = AtomicUsize::new(0);
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fn _get_freelist_pagecount(debug: bool, o: u32, f: u32, set_not_clear: bool) -> usize {
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let mut pagecount = 0;
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let freelist = FREELIST.lock();
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let abs_off = unsafe { ALLOCATOR_DATA.abs_off };
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for order in 0..=MAX_ORDER {
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if debug {
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log::info!("ORDER{order}");
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}
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let Some(mut p2frame) = freelist[order as usize] else {
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continue;
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};
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assert!(p2frame.is_aligned_to_order(order));
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assert!(p2frame.start_address().data() >= abs_off);
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pagecount += 1 << order;
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let mut i = 0;
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loop {
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if debug {
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log::info!("FRAME {p2frame:?}");
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}
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//let next_info = get_free_alloc_page_info(p2frame);
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let Some(next_info) = get_page_info(p2frame).unwrap().as_free() else {
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drop(freelist);
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if !debug {
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log::info!("M{o}F{f}");
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//_get_freelist_pagecount(true, o, f, false);
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debug_freelist();
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}
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panic!("i{i}o{order}");
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};
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if set_not_clear {
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assert!(next_info.next.fetch_or(RC_USED_NOT_FREE, Ordering::Relaxed) & RC_USED_NOT_FREE == 0);
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} else {
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next_info.next.fetch_and(!RC_USED_NOT_FREE, Ordering::Relaxed);
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}
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if i == 0 {
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assert!(next_info.prev().frame().is_none());
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} else {
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assert!(next_info.prev().frame().is_some());
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}
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let next_frame = next_info.next().frame();
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assert_eq!(next_info.next().order(), order, "order mismatch for frame {p2frame:?} i{i} f{next_frame:?}");
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assert_eq!(next_info.prev().order(), order);
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//assert_eq!(next_info.next().order(), order);
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/*if next_info.order() != order {
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log::info!("BAD ORDER FOR {next_frame:?}");
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}*/
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let Some(next) = next_frame else {
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break;
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};
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assert!(next.start_address().data() >= abs_off);
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pagecount += 1 << order;
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p2frame = next;
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i += 1;
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}
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}
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for (frame, info) in unsafe { ALLOCATOR_DATA.sections.iter().flat_map(|s| s.frames.iter().enumerate().map(|(i, f)| (s.base.next_by(i), f))) } {
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let Some(free) = info.as_free() else {
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break;
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};
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let order = free.next().order();
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assert_eq!(free.prev().order(), order);
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if free.prev().frame().is_none() {
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assert_eq!(freelist[order as usize], Some(frame));
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} else {
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assert!(free.next().frame().is_some());
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}
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}
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pagecount
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}
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unsafe fn deallocate_p2frame(orig_frame: Frame, order: u32) {
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let mut freelist = FREELIST.lock();
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let mut largest_order = order;
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let mut current = orig_frame;
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for merge_order in order..MAX_ORDER {
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// Because there's a PageInfo, this frame must be allocator-owned. We need to be very
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// careful with who owns this page, as the refcount can be anything from 0 (undefined) to
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// 2^addrwidth - 1. However, allocation and deallocation must be synchronized (the "next"
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// word of the PageInfo).
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let sibling = Frame::containing_address(PhysicalAddress::new(current.start_address().data() ^ (PAGE_SIZE << merge_order)));
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let Some(cur_info) = get_page_info(current) else {
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unreachable!("attempting to free non-allocator-owned page");
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};
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let Some(sib_info) = get_page_info(sibling) else {
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// The frame that was deallocated, was at the unaligned start or end of its section
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// (i.e. there aren't 1 << merge_order additional pages).
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break;
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};
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let PageInfoKind::Free(sib_info) = sib_info.kind() else {
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// The frame is currently in use (refcounted). It cannot be merged!
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break;
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};
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// If the sibling p2frame has lower order than merge_order, it cannot be merged into
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// current.
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if sib_info.next().order() < merge_order {
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break;
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}
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assert!(!(sib_info.next().order() > merge_order), "sibling page has unaligned order or contains current page");
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//log::info!("MERGED {lo:?} WITH {hi:?} ORDER {order}");
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if let Some(sib_prev) = sib_info.prev().frame() {
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get_free_alloc_page_info(sib_prev).set_next(sib_info.next());
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} else {
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assert_eq!(freelist[merge_order as usize], Some(sibling));
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assert!(sib_info.next().frame().map_or(true, |f| f.is_aligned_to_order(merge_order)));
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assert_eq!(sib_info.next().order(), merge_order);
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freelist[merge_order as usize] = sib_info.next().frame();
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}
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if let Some(sib_next) = sib_info.next().frame() {
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get_free_alloc_page_info(sib_next).set_prev(sib_info.prev());
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}
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current = Frame::containing_address(PhysicalAddress::new(current.start_address().data() & !(PAGE_SIZE << merge_order)));
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largest_order = merge_order + 1;
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}
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get_page_info(current)
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.expect("freeing frame without PageInfo")
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.make_free(largest_order);
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let new_head = current;
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assert!(new_head.is_aligned_to_order(largest_order));
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if let Some(old_head) = freelist[largest_order as usize].replace(new_head) {
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//log::info!("HEAD {:p} FREED {:p} BARRIER {:p}", get_page_info(old_head).unwrap(), get_page_info(frame).unwrap(), unsafe { ALLOCATOR_DATA.abs_off as *const u8 });
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let old_head_info = get_free_alloc_page_info(old_head);
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let new_head_info = get_free_alloc_page_info(new_head);
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new_head_info.set_next(P2Frame::new(Some(old_head), largest_order));
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new_head_info.set_prev(P2Frame::new(None, largest_order));
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old_head_info.set_prev(P2Frame::new(Some(new_head), largest_order));
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}
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//log::info!("FREED {frame:?}+2^{order}");
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}
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pub unsafe fn deallocate_frame(frame: Frame) {
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deallocate_p2frame(frame, 0)
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}
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const ORDER_COUNT: u32 = 11;
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const MAX_ORDER: u32 = ORDER_COUNT - 1;
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pub struct FreeList {
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for_orders: [Option<Frame>; ORDER_COUNT as usize],
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}
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#[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
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pub struct Frame {
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// On x86/x86_64, all memory below 1 MiB is reserved, and although some frames in that range
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// may end up in the paging code, it's very unlikely that frame 0x0 would.
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physaddr: NonZeroUsize,
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}
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/// Option<Frame> combined with power-of-two size.
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#[derive(Clone, Copy)]
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struct P2Frame(usize);
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impl P2Frame {
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fn new(frame: Option<Frame>, order: u32) -> Self {
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Self(
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frame.map_or(0, |f| f.physaddr.get()) | (order as usize),
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)
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}
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fn get(self) -> (Option<Frame>, u32) {
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//assert_ne!(self.0 & RC_USED_NOT_FREE, RC_USED_NOT_FREE);
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let page_off_mask = PAGE_SIZE - 1;
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(NonZeroUsize::new(self.0 & !page_off_mask & !(RC_USED_NOT_FREE)).map(|physaddr| Frame { physaddr }), (self.0 & page_off_mask) as u32)
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}
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fn frame(self) -> Option<Frame> {
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self.get().0
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}
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fn order(self) -> u32 {
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self.get().1
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}
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}
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impl core::fmt::Debug for P2Frame {
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fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
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let (frame, order) = self.get();
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write!(f, "[frame at {frame:?}] order {order}")
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}
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}
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impl core::fmt::Debug for Frame {
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fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
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write!(
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f,
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"[frame at {:p}]",
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self.start_address().data() as *const u8
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)
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}
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}
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impl Frame {
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/// Get the address of this frame
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// TODO: Remove
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pub fn start_address(&self) -> PhysicalAddress {
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PhysicalAddress::new(self.physaddr.get())
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}
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/// Create a frame containing `address`
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pub fn containing(address: PhysicalAddress) -> Frame {
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Frame {
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physaddr: NonZeroUsize::new(address.data() & !PAGE_MASK).expect("frame 0x0 is reserved"),
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}
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}
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// TODO: Remove
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pub fn containing_address(address: PhysicalAddress) -> Frame {
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Self::containing(address)
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}
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pub fn base(self) -> PhysicalAddress {
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PhysicalAddress::new(self.physaddr.get())
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}
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//TODO: Set private
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pub fn range_inclusive(start: Frame, end: Frame) -> impl Iterator<Item = Frame> {
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(start.physaddr.get()..=end.physaddr.get()).step_by(PAGE_SIZE).map(|number| Frame { physaddr: NonZeroUsize::new(number).unwrap() })
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}
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pub fn next_by(self, n: usize) -> Self {
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Self {
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physaddr: self
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.physaddr
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.get()
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.checked_add(n * PAGE_SIZE)
|
|
.and_then(NonZeroUsize::new)
|
|
.expect("overflow in Frame::next_by"),
|
|
}
|
|
}
|
|
pub fn prev_by(self, n: usize) -> Self {
|
|
Self {
|
|
physaddr: self.physaddr.get().checked_sub(n.checked_mul(PAGE_SIZE).expect("unreasonable n")).and_then(NonZeroUsize::new).expect("overflow in Frame::prev_by"),
|
|
}
|
|
}
|
|
pub fn align_down_to_order(self, order: u32) -> Option<Self> {
|
|
Some(Self { physaddr: NonZeroUsize::new(self.physaddr.get() / (PAGE_SIZE << order) * (PAGE_SIZE << order))? })
|
|
}
|
|
pub fn offset_from(self, from: Self) -> usize {
|
|
self.physaddr
|
|
.get()
|
|
.checked_sub(from.physaddr.get())
|
|
.expect("overflow in Frame::offset_from") / PAGE_SIZE
|
|
}
|
|
pub fn is_aligned_to_order(self, order: u32) -> bool {
|
|
self.start_address().data() % (PAGE_SIZE << order) == 0
|
|
}
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
pub struct Enomem;
|
|
|
|
impl From<Enomem> for Error {
|
|
fn from(_: Enomem) -> Self {
|
|
Self::new(ENOMEM)
|
|
}
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
pub struct RaiiFrame {
|
|
inner: Frame,
|
|
}
|
|
impl RaiiFrame {
|
|
pub fn allocate() -> Result<Self, Enomem> {
|
|
init_frame(RefCount::One)
|
|
.map_err(|_| Enomem)
|
|
.map(|inner| Self { inner })
|
|
}
|
|
pub fn get(&self) -> Frame {
|
|
self.inner
|
|
}
|
|
}
|
|
|
|
impl Drop for RaiiFrame {
|
|
fn drop(&mut self) {
|
|
if get_page_info(self.inner)
|
|
.expect("RaiiFrame lacking PageInfo")
|
|
.remove_ref() == None
|
|
{
|
|
unsafe {
|
|
crate::memory::deallocate_frames(self.inner, 1);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// TODO: Make PageInfo a union, since *every* allocated page will have an associated PageInfo.
|
|
// Pages that aren't AddrSpace data pages, such as paging-structure pages, might use the memory
|
|
// occupied by a PageInfo for something else, potentially allowing paging structure-level CoW too.
|
|
//
|
|
// TODO: Another interesting possibility would be to use a slab allocator for (ideally
|
|
// power-of-two) allocations smaller than a page, in which case this PageInfo might store a bitmap
|
|
// of used sub-allocations.
|
|
//
|
|
// TODO: Alternatively or in conjunction, the PageInfo can store the number of used entries for
|
|
// each page table, possibly even recursively (total number of mapped pages).
|
|
// NOTE: init_sections depends on the default initialized value consisting of all zero bytes.
|
|
#[derive(Debug)]
|
|
pub struct PageInfo {
|
|
/// Stores the reference count to this page, i.e. the number of present page table entries that
|
|
/// point to this particular frame.
|
|
///
|
|
/// Bits 0..=N-1 are used for the actual reference count, whereas bit N-1 indicates the page is
|
|
/// shared if set, and CoW if unset. The flag is not meaningful when the refcount is 0 or 1.
|
|
pub refcount: AtomicUsize,
|
|
|
|
// TODO: Add one flag indicating whether the page contents is zeroed? Or should this primarily
|
|
// be managed by the memory allocator first?
|
|
pub next: AtomicUsize,
|
|
}
|
|
|
|
enum PageInfoKind<'info> {
|
|
Used(PageInfoUsed<'info>),
|
|
Free(PageInfoFree<'info>),
|
|
}
|
|
struct PageInfoUsed<'info> {
|
|
refcount: &'info AtomicUsize,
|
|
_misc: &'info AtomicUsize,
|
|
}
|
|
struct PageInfoFree<'info> {
|
|
prev: &'info AtomicUsize,
|
|
next: &'info AtomicUsize,
|
|
}
|
|
|
|
// There should be at least 2 bits available; even with a 4k page size on a 32-bit system (where a
|
|
// paging structure node is itself a 4k page size, i.e. on i386 with 1024 32-bit entries), there
|
|
// simply cannot be more than 2^30 entries pointing to the same page. However, to be able to use
|
|
// fetch_add safely, we reserve another bit (which makes fetch_add safe if properly reverted, and
|
|
// there aren't more than 2^(BITS-2) CPUs on the system).
|
|
|
|
// Indicates whether the page is free (and thus managed by the allocator), or owned (and thus
|
|
// managed by the kernel heap, or most commonly, the virtual memory system). The refcount may
|
|
// increase or decrease with fetch_add, but must never flip this bit.
|
|
const RC_USED_NOT_FREE: usize = 1 << (usize::BITS - 1);
|
|
|
|
// Only valid if RC_USED. Controls whether the page is CoW (map readonly, on page fault, copy and
|
|
// remap writable) or shared (mapped writable in the first place).
|
|
const RC_SHARED_NOT_COW: usize = 1 << (usize::BITS - 2);
|
|
|
|
// The page refcount limit. This acts as a buffer zone allowing subsequent fetch_sub to correct
|
|
// overflow, which works as long as there's fewer CPUs than RC_MAX itself (and interrupts are
|
|
// disabled).
|
|
const RC_MAX: usize = 1 << (usize::BITS - 3);
|
|
|
|
const RC_COUNT_MASK: usize = !(RC_USED_NOT_FREE | RC_SHARED_NOT_COW);
|
|
|
|
// TODO: Use some of the flag bits as a tag, indicating the type of page (e.g. paging structure,
|
|
// userspace data page, or kernel heap page). This could be done only when debug assertions are
|
|
// enabled.
|
|
bitflags::bitflags! {
|
|
#[derive(Debug)]
|
|
pub struct FrameFlags: usize {
|
|
const NONE = 0;
|
|
}
|
|
}
|
|
|
|
static mut ALLOCATOR_DATA: AllocatorData = AllocatorData { sections: &[], abs_off: 0 };
|
|
|
|
struct AllocatorData {
|
|
// TODO: Memory hotplugging?
|
|
sections: &'static [Section],
|
|
abs_off: usize,
|
|
}
|
|
static FREELIST: Mutex<[Option<Frame>; ORDER_COUNT as usize]> = Mutex::new([None; ORDER_COUNT as usize]);
|
|
|
|
pub struct Section {
|
|
base: Frame,
|
|
frames: &'static [PageInfo],
|
|
}
|
|
|
|
pub const MAX_SECTION_SIZE_BITS: u32 = 27;
|
|
pub const MAX_SECTION_SIZE: usize = 1 << MAX_SECTION_SIZE_BITS;
|
|
pub const MAX_SECTION_PAGE_COUNT: usize = MAX_SECTION_SIZE / PAGE_SIZE;
|
|
|
|
const _: () = {
|
|
assert!(mem::size_of::<PageInfo>().is_power_of_two());
|
|
};
|
|
|
|
#[cold]
|
|
fn init_sections(mut allocator: BumpAllocator<RmmA>) {
|
|
let (free_areas, offset_into_first_free_area) = allocator.free_areas();
|
|
|
|
let free_areas_iter = || free_areas.iter().copied().enumerate().map(|(i, area)| if i == 0 {
|
|
rmm::MemoryArea {
|
|
base: area.base.add(offset_into_first_free_area),
|
|
size: area.size - offset_into_first_free_area,
|
|
}
|
|
} else {
|
|
area
|
|
});
|
|
|
|
let sections: &'static mut [Section] = {
|
|
let max_section_count: usize = free_areas_iter().map(|area| {
|
|
let aligned_end = area.base.add(area.size).data().next_multiple_of(MAX_SECTION_SIZE);
|
|
let aligned_start = area.base.data() / MAX_SECTION_SIZE * MAX_SECTION_SIZE;
|
|
|
|
(aligned_end - aligned_start) / MAX_SECTION_SIZE
|
|
}).sum();
|
|
let section_array_page_count = (max_section_count * mem::size_of::<Section>()).div_ceil(PAGE_SIZE);
|
|
|
|
unsafe {
|
|
let base = allocator.allocate(FrameCount::new(section_array_page_count)).expect("failed to allocate sections array");
|
|
core::slice::from_raw_parts_mut(RmmA::phys_to_virt(base).data() as *mut Section, max_section_count)
|
|
}
|
|
};
|
|
|
|
let mut iter = free_areas_iter().peekable();
|
|
|
|
let mut i = 0;
|
|
|
|
while let Some(mut memory_map_area) = iter.next() {
|
|
// TODO: NonZeroUsize
|
|
assert_ne!(
|
|
memory_map_area.size, 0,
|
|
"RMM should enforce areas are not zeroed"
|
|
);
|
|
|
|
// TODO: Should RMM do this?
|
|
|
|
while let Some(next_area) = iter.peek() && next_area.base == memory_map_area.base.add(memory_map_area.size) {
|
|
memory_map_area.size += next_area.size;
|
|
let _ = iter.next();
|
|
}
|
|
|
|
assert_eq!(
|
|
memory_map_area.base.data() % PAGE_SIZE,
|
|
0,
|
|
"RMM should enforce area alignment"
|
|
);
|
|
assert_eq!(
|
|
memory_map_area.size % PAGE_SIZE,
|
|
0,
|
|
"RMM should enforce area length alignment"
|
|
);
|
|
|
|
let mut pages_left = memory_map_area.size.div_floor(PAGE_SIZE);
|
|
let mut base = Frame::containing_address(memory_map_area.base);
|
|
|
|
while pages_left > 0 {
|
|
let page_info_max_count = core::cmp::min(pages_left, MAX_SECTION_PAGE_COUNT);
|
|
let pages_to_next_section = (MAX_SECTION_SIZE - (base.start_address().data() % MAX_SECTION_SIZE)) / PAGE_SIZE;
|
|
let page_info_count = core::cmp::min(page_info_max_count, pages_to_next_section);
|
|
|
|
let page_info_array_size_pages = (page_info_count * mem::size_of::<PageInfo>()).div_ceil(PAGE_SIZE);
|
|
let page_info_array = unsafe {
|
|
let base = allocator.allocate(FrameCount::new(page_info_array_size_pages)).expect("failed to allocate page info array");
|
|
core::slice::from_raw_parts_mut(RmmA::phys_to_virt(base).data() as *mut PageInfo, page_info_count)
|
|
};
|
|
for p in &*page_info_array {
|
|
assert_eq!(p.next.load(Ordering::Relaxed), 0);
|
|
assert_eq!(p.refcount.load(Ordering::Relaxed), 0);
|
|
}
|
|
|
|
sections[i] = Section {
|
|
base,
|
|
frames: page_info_array,
|
|
};
|
|
i += 1;
|
|
|
|
pages_left -= page_info_count;
|
|
base = base.next_by(page_info_count);
|
|
}
|
|
}
|
|
|
|
sections.sort_unstable_by_key(|s| s.base);
|
|
|
|
// The bump allocator has been used during the section array and page info array allocation
|
|
// phases, which means some of the PageInfos will be pointing to those arrays themselves.
|
|
// Mark those pages as used!
|
|
'sections: for section in &*sections {
|
|
for (off, page_info) in section.frames.iter().enumerate() {
|
|
let frame = section.base.next_by(off);
|
|
if frame.start_address() >= allocator.abs_offset() {
|
|
break 'sections;
|
|
}
|
|
//log::info!("MARKING {frame:?} AS USED");
|
|
page_info.refcount.store(RC_USED_NOT_FREE, Ordering::Relaxed);
|
|
page_info.next.store(0, Ordering::Relaxed);
|
|
}
|
|
}
|
|
|
|
let mut first_pages: [Option<(Frame, &'static PageInfo)>; ORDER_COUNT as usize] = [None; ORDER_COUNT as usize];
|
|
let mut last_pages = first_pages;
|
|
|
|
let mut append_page = |page: Frame, info: &'static PageInfo, order| {
|
|
let this_page = (page, info);
|
|
|
|
if page.start_address() < allocator.abs_offset() {
|
|
return;
|
|
}
|
|
assert!(info.as_free().is_some());
|
|
assert!(this_page.0.is_aligned_to_order(order));
|
|
assert_eq!(info.next.load(Ordering::Relaxed), 0);
|
|
assert_eq!(info.refcount.load(Ordering::Relaxed), 0);
|
|
|
|
let last_page = last_pages[order as usize].replace(this_page);
|
|
|
|
if let Some((last_frame, last_page_info)) = last_page {
|
|
let last_info = last_page_info.as_free().unwrap();
|
|
|
|
//assert_eq!(last_info.next().order(), order);
|
|
assert_eq!(last_info.next().frame(), None);
|
|
|
|
last_info.set_next(P2Frame::new(Some(page), order));
|
|
info.as_free().unwrap().set_prev(P2Frame::new(Some(last_frame), order));
|
|
} else {
|
|
first_pages[order as usize] = Some(this_page);
|
|
info.as_free().unwrap().set_prev(P2Frame::new(None, order));
|
|
info.as_free().unwrap().set_next(P2Frame::new(None, order));
|
|
}
|
|
};
|
|
unsafe {
|
|
ALLOCATOR_DATA = AllocatorData { sections, abs_off: allocator.abs_offset().data() };
|
|
}
|
|
|
|
for section in &*sections {
|
|
let mut base = section.base;
|
|
let mut frames = section.frames;
|
|
|
|
for order in 0..=MAX_ORDER {
|
|
let pages_for_current_order = 1 << order;
|
|
|
|
if !frames.is_empty() && order != MAX_ORDER && !base.is_aligned_to_order(order + 1) {
|
|
// The first section page is not aligned to the next order size.
|
|
|
|
//log::info!("ORDER {order}: FIRST {base:?}");
|
|
append_page(base, &frames[0], order);
|
|
|
|
base = base.next_by(pages_for_current_order);
|
|
frames = &frames[pages_for_current_order..];
|
|
} else {
|
|
//log::info!("ORDER {order}: FIRST SKIP");
|
|
}
|
|
|
|
if order != MAX_ORDER && !base.next_by(frames.len()).is_aligned_to_order(order + 1) {
|
|
// The last section page is not aligned to the next order size.
|
|
|
|
let off = frames.len() - pages_for_current_order;
|
|
let final_page = base.next_by(off);
|
|
|
|
//log::info!("ORDER {order}: LAST {final_page:?}");
|
|
append_page(final_page, &frames[off], order);
|
|
|
|
frames = &frames[..frames.len() - pages_for_current_order];
|
|
} else {
|
|
//log::info!("ORDER {order}: LAST SKIP");
|
|
}
|
|
|
|
if order == MAX_ORDER {
|
|
assert_eq!(frames.len() % pages_for_current_order, 0);
|
|
assert!(base.is_aligned_to_order(MAX_ORDER));
|
|
|
|
for (off, info) in frames.iter().enumerate().step_by(pages_for_current_order) {
|
|
append_page(base.next_by(off), info, MAX_ORDER);
|
|
}
|
|
}
|
|
}
|
|
|
|
//log::info!("SECTION from {:?}, {} pages, array at {:p}", section.base, section.frames.len(), section.frames);
|
|
}
|
|
for (order, tuple_opt) in last_pages.iter().enumerate() {
|
|
let Some((frame, info)) = tuple_opt else { continue; };
|
|
assert!(frame.is_aligned_to_order(order as u32));
|
|
let free = info.as_free().unwrap();
|
|
assert_eq!(free.prev().order(), order as u32);
|
|
free.set_next(P2Frame::new(None, order as u32));
|
|
}
|
|
|
|
*FREELIST.lock() = first_pages.map(|pair| pair.map(|(frame, _)| frame));
|
|
|
|
debug_freelist();
|
|
log::info!("Initial freelist consistent");
|
|
|
|
}
|
|
fn debug_freelist() {
|
|
let freelist = FREELIST.lock();
|
|
|
|
for order in 0..=MAX_ORDER {
|
|
let Some(first_frame) = freelist[order as usize] else {
|
|
continue;
|
|
};
|
|
log::info!("ORDER {order} FIRST {first_frame:?}");
|
|
let mut frame = first_frame;
|
|
|
|
if order == MAX_ORDER { break }
|
|
let mut count = 1;
|
|
while let p2next = get_page_info(frame).unwrap_or_else(|| panic!("no page info: {frame:?}")).as_free().expect("not free").next() && let _ = assert_eq!(p2next.order(), order) && let Some(next) = p2next.frame() {
|
|
log::info!("ORDER {order} THEN {next:?}");
|
|
frame = next;
|
|
count += 1;
|
|
}
|
|
log::info!("ORDER {order}: {count} p2frames");
|
|
}
|
|
}
|
|
|
|
#[cold]
|
|
pub fn init_mm(allocator: BumpAllocator<RmmA>) {
|
|
init_sections(allocator);
|
|
|
|
unsafe {
|
|
let the_frame = allocate_frame().expect("failed to allocate static zeroed frame");
|
|
let the_info = get_page_info(the_frame).expect("static zeroed frame had no PageInfo");
|
|
the_info
|
|
.refcount
|
|
.store(RefCount::One.to_raw(), Ordering::Relaxed);
|
|
|
|
THE_ZEROED_FRAME.get().write(Some((the_frame, the_info)));
|
|
}
|
|
}
|
|
#[derive(Debug)]
|
|
pub enum AddRefError {
|
|
CowToShared,
|
|
SharedToCow,
|
|
RcOverflow,
|
|
}
|
|
impl PageInfo {
|
|
pub fn new() -> Self {
|
|
Self {
|
|
refcount: AtomicUsize::new(0),
|
|
next: AtomicUsize::new(0),
|
|
}
|
|
}
|
|
fn kind(&self) -> PageInfoKind<'_> {
|
|
let prev = self.refcount.load(Ordering::Relaxed);
|
|
|
|
if prev & RC_USED_NOT_FREE == RC_USED_NOT_FREE {
|
|
PageInfoKind::Used(PageInfoUsed { refcount: &self.refcount, _misc: &self.next })
|
|
} else {
|
|
PageInfoKind::Free(PageInfoFree { prev: &self.refcount, next: &self.next })
|
|
}
|
|
}
|
|
fn as_free(&self) -> Option<PageInfoFree<'_>> {
|
|
match self.kind() {
|
|
PageInfoKind::Free(f) => Some(f),
|
|
PageInfoKind::Used(_) => None,
|
|
}
|
|
}
|
|
fn as_used(&self) -> Option<PageInfoUsed<'_>> {
|
|
match self.kind() {
|
|
PageInfoKind::Used(f) => Some(f),
|
|
PageInfoKind::Free(_) => None,
|
|
}
|
|
}
|
|
pub fn add_ref(&self, kind: RefKind) -> Result<(), AddRefError> {
|
|
match (self.refcount().expect("cannot add_ref to free frame"), kind) {
|
|
(RefCount::One, RefKind::Cow) => self.refcount.store(RC_USED_NOT_FREE | 1, Ordering::Relaxed),
|
|
(RefCount::One, RefKind::Shared) => self.refcount.store(RC_USED_NOT_FREE | 1 | RC_SHARED_NOT_COW, Ordering::Relaxed),
|
|
(RefCount::Cow(_), RefKind::Cow) | (RefCount::Shared(_), RefKind::Shared) => {
|
|
let old = self.refcount.fetch_add(1, Ordering::Relaxed);
|
|
|
|
if (old & RC_COUNT_MASK) >= RC_MAX {
|
|
self.refcount.fetch_sub(1, Ordering::Relaxed);
|
|
return Err(AddRefError::RcOverflow);
|
|
}
|
|
}
|
|
(RefCount::Cow(_), RefKind::Shared) => return Err(AddRefError::CowToShared),
|
|
(RefCount::Shared(_), RefKind::Cow) => return Err(AddRefError::SharedToCow),
|
|
}
|
|
Ok(())
|
|
}
|
|
#[must_use = "must deallocate if refcount reaches None"]
|
|
pub fn remove_ref(&self) -> Option<RefCount> {
|
|
match self.refcount() {
|
|
None => panic!("refcount was already zero when calling remove_ref!"),
|
|
Some(RefCount::One) => {
|
|
// Used to be RC_USED_NOT_FREE | ?RC_SHARED_NOT_COW | 0, now becomes 0
|
|
//self.refcount.store(0, Ordering::Relaxed);
|
|
|
|
None
|
|
}
|
|
Some(RefCount::Cow(_) | RefCount::Shared(_)) => RefCount::from_raw({
|
|
// Used to be RC_USED_NOT_FREE | ?RC_SHARED_NOW_COW | n, now becomes
|
|
// RC_USED_NOT_FREE | ?RC_SHARED_NOW_COW | n - 1
|
|
(self.refcount.fetch_sub(1, Ordering::Relaxed) - 1) | RC_USED_NOT_FREE
|
|
}),
|
|
}
|
|
}
|
|
#[track_caller]
|
|
pub fn allows_writable(&self) -> bool {
|
|
match self.refcount().expect("using allows_writable on free page!") {
|
|
RefCount::One => true,
|
|
RefCount::Cow(_) => false,
|
|
RefCount::Shared(_) => true,
|
|
}
|
|
}
|
|
|
|
pub fn refcount(&self) -> Option<RefCount> {
|
|
let refcount = self.refcount.load(Ordering::Relaxed);
|
|
|
|
RefCount::from_raw(refcount)
|
|
}
|
|
fn make_free(&self, order: u32) -> PageInfoFree<'_> {
|
|
// Order needs to be known so we don't for example merge A: [A] A A A B: [B] U U U into a
|
|
// 2^3 page (if U indicates "used").
|
|
self.refcount.store(order as usize, Ordering::Relaxed);
|
|
self.next.store(order as usize, Ordering::Relaxed);
|
|
|
|
PageInfoFree {
|
|
next: &self.next,
|
|
prev: &self.refcount,
|
|
}
|
|
}
|
|
}
|
|
impl PageInfoFree<'_> {
|
|
fn next(&self) -> P2Frame {
|
|
P2Frame(self.next.load(Ordering::Relaxed))
|
|
}
|
|
#[track_caller]
|
|
fn set_next(&self, next: P2Frame) {
|
|
assert!(next.frame().map_or(true, |f| f.is_aligned_to_order(next.order())));
|
|
self.next.store(next.0, Ordering::Relaxed)
|
|
}
|
|
fn prev(&self) -> P2Frame {
|
|
P2Frame(self.prev.load(Ordering::Relaxed))
|
|
}
|
|
fn set_prev(&self, prev: P2Frame) {
|
|
assert!(prev.frame().map_or(true, |f| f.is_aligned_to_order(prev.order())));
|
|
self.prev.store(prev.0, Ordering::Relaxed)
|
|
}
|
|
fn mark_used(&self) {
|
|
// Order is irrelevant if marked "used"
|
|
self.prev.store(RC_USED_NOT_FREE, Ordering::Relaxed);
|
|
self.next.store(0, Ordering::Relaxed);
|
|
}
|
|
}
|
|
impl<'a> PageInfoUsed<'a> {
|
|
fn make_free(self, order: u32) -> PageInfoFree<'a> {
|
|
// !RC_USED_NOT_FREE
|
|
self.refcount.store(order as usize, Ordering::Relaxed);
|
|
self._misc.store(order as usize, Ordering::Relaxed);
|
|
|
|
PageInfoFree {
|
|
next: &self._misc,
|
|
prev: &self.refcount,
|
|
}
|
|
}
|
|
}
|
|
#[derive(Clone, Copy, Debug, PartialEq)]
|
|
pub enum RefKind {
|
|
Cow,
|
|
Shared,
|
|
// TODO: Observer?
|
|
}
|
|
#[derive(Clone, Copy, Debug, PartialEq)]
|
|
pub enum RefCount {
|
|
One,
|
|
Shared(NonZeroUsize),
|
|
Cow(NonZeroUsize),
|
|
}
|
|
impl RefCount {
|
|
pub fn from_raw(raw: usize) -> Option<Self> {
|
|
if raw & RC_USED_NOT_FREE != RC_USED_NOT_FREE {
|
|
return None;
|
|
}
|
|
let refcount_minus_one = raw & !(RC_SHARED_NOT_COW | RC_USED_NOT_FREE);
|
|
let nz_refcount = NonZeroUsize::new(refcount_minus_one + 1).unwrap();
|
|
|
|
Some(if nz_refcount.get() == 1 {
|
|
RefCount::One
|
|
} else if raw & RC_SHARED_NOT_COW == RC_SHARED_NOT_COW {
|
|
RefCount::Shared(nz_refcount)
|
|
} else {
|
|
RefCount::Cow(nz_refcount)
|
|
})
|
|
|
|
}
|
|
pub fn to_raw(self) -> usize {
|
|
match self {
|
|
Self::One => 0 | RC_USED_NOT_FREE,
|
|
Self::Shared(inner) => (inner.get() - 1) | RC_SHARED_NOT_COW | RC_USED_NOT_FREE,
|
|
Self::Cow(inner) => (inner.get() - 1) | RC_USED_NOT_FREE,
|
|
}
|
|
}
|
|
}
|
|
pub fn get_page_info(frame: Frame) -> Option<&'static PageInfo> {
|
|
let sections = unsafe { ALLOCATOR_DATA.sections };
|
|
|
|
let idx_res = sections.binary_search_by_key(&frame, |section| section.base);
|
|
|
|
if idx_res == Err(0) {
|
|
// The frame is before the first section
|
|
return None;
|
|
}
|
|
|
|
// binary_search_by_key returns either Ok(where it was found) or Err(where it would have been
|
|
// inserted). The base obviously cannot have been exactly matched from an entry at an
|
|
// out-of-bounds index, so the only Err(i) where i - 1 is out of bounds, is for i=0. That
|
|
// has already been checked.
|
|
let section = §ions[idx_res.unwrap_or_else(|e| e - 1)];
|
|
|
|
section.frames.get(frame.offset_from(section.base))
|
|
|
|
/*
|
|
sections
|
|
.range(..=frame)
|
|
.next_back()
|
|
.filter(|(base, section)| frame <= base.next_by(section.frames.len()))
|
|
.map(|(base, section)| PageInfoHandle { section, idx: frame.offset_from(*base) })
|
|
*/
|
|
}
|
|
|
|
#[track_caller]
|
|
fn get_free_alloc_page_info(frame: Frame) -> PageInfoFree<'static> {
|
|
let i = get_page_info(frame).unwrap_or_else(|| panic!("allocator-owned frames need a PageInfo, but none for {frame:?}"));
|
|
i.as_free().unwrap()//.unwrap_or_else(|| panic!("expected frame to be free, but {frame:?} wasn't, in {i:?}"))
|
|
}
|
|
|
|
pub struct Segv;
|
|
|
|
bitflags! {
|
|
/// Arch-generic page fault flags, modeled after x86's error code.
|
|
///
|
|
/// This may change when arch-specific features are utilized better.
|
|
pub struct GenericPfFlags: u32 {
|
|
const PRESENT = 1 << 0;
|
|
const INVOLVED_WRITE = 1 << 1;
|
|
const USER_NOT_SUPERVISOR = 1 << 2;
|
|
const INSTR_NOT_DATA = 1 << 3;
|
|
// "reserved bits" on x86
|
|
const INVL = 1 << 31;
|
|
}
|
|
}
|
|
|
|
pub trait ArchIntCtx {
|
|
fn ip(&self) -> usize;
|
|
fn recover_and_efault(&mut self);
|
|
}
|
|
|
|
pub fn page_fault_handler(
|
|
stack: &mut impl ArchIntCtx,
|
|
code: GenericPfFlags,
|
|
faulting_address: VirtualAddress,
|
|
) -> Result<(), Segv> {
|
|
let faulting_page = Page::containing_address(faulting_address);
|
|
|
|
let usercopy_region = __usercopy_start()..__usercopy_end();
|
|
|
|
// TODO: Most likely not necessary, but maybe also check that the faulting address is not too
|
|
// close to USER_END.
|
|
let address_is_user = faulting_address.kind() == TableKind::User;
|
|
|
|
let invalid_page_tables = code.contains(GenericPfFlags::INVL);
|
|
let caused_by_user = code.contains(GenericPfFlags::USER_NOT_SUPERVISOR);
|
|
let caused_by_kernel = !caused_by_user;
|
|
let caused_by_write = code.contains(GenericPfFlags::INVOLVED_WRITE);
|
|
let caused_by_instr_fetch = code.contains(GenericPfFlags::INSTR_NOT_DATA);
|
|
let is_usercopy = usercopy_region.contains(&stack.ip());
|
|
|
|
let mode = match (caused_by_write, caused_by_instr_fetch) {
|
|
(true, false) => AccessMode::Write,
|
|
(false, false) => AccessMode::Read,
|
|
(false, true) => AccessMode::InstrFetch,
|
|
(true, true) => {
|
|
unreachable!("page fault cannot be caused by both instruction fetch and write")
|
|
}
|
|
};
|
|
|
|
if invalid_page_tables {
|
|
// TODO: Better error code than Segv?
|
|
return Err(Segv);
|
|
}
|
|
|
|
if address_is_user && (caused_by_user || is_usercopy) {
|
|
match context::memory::try_correcting_page_tables(faulting_page, mode) {
|
|
Ok(()) => return Ok(()),
|
|
Err(PfError::Oom) => todo!("oom"),
|
|
Err(PfError::Segv | PfError::RecursionLimitExceeded) => (),
|
|
Err(PfError::NonfatalInternalError) => todo!(),
|
|
}
|
|
}
|
|
|
|
if address_is_user && caused_by_kernel && mode != AccessMode::InstrFetch && is_usercopy {
|
|
stack.recover_and_efault();
|
|
return Ok(());
|
|
}
|
|
|
|
Err(Segv)
|
|
}
|
|
static THE_ZEROED_FRAME: SyncUnsafeCell<Option<(Frame, &'static PageInfo)>> =
|
|
SyncUnsafeCell::new(None);
|
|
|
|
pub fn the_zeroed_frame() -> (Frame, &'static PageInfo) {
|
|
unsafe {
|
|
THE_ZEROED_FRAME
|
|
.get()
|
|
.read()
|
|
.expect("zeroed frame must be initialized")
|
|
}
|
|
}
|
|
|
|
pub fn init_frame(init_rc: RefCount) -> Result<Frame, PfError> {
|
|
let new_frame = crate::memory::allocate_frame().ok_or(PfError::Oom)?;
|
|
let page_info = get_page_info(new_frame).unwrap_or_else(|| panic!("all allocated frames need an associated page info, {:?} didn't", new_frame));
|
|
assert_eq!(page_info.refcount(), Some(RefCount::One));
|
|
page_info.refcount.store(init_rc.to_raw(), Ordering::Relaxed);
|
|
|
|
Ok(new_frame)
|
|
}
|
|
#[derive(Debug)]
|
|
pub struct TheFrameAllocator;
|
|
|
|
impl FrameAllocator for TheFrameAllocator {
|
|
unsafe fn allocate(&mut self, count: FrameCount) -> Option<PhysicalAddress> {
|
|
allocate_frames(count.data()).map(|f| f.start_address())
|
|
}
|
|
unsafe fn free(&mut self, address: PhysicalAddress, count: FrameCount) {
|
|
deallocate_frames(Frame::containing_address(address), count.data())
|
|
}
|
|
unsafe fn usage(&self) -> rmm::FrameUsage {
|
|
todo!()
|
|
}
|
|
}
|
|
impl FreeList {
|
|
pub fn new() -> Self {
|
|
Self {
|
|
for_orders: [None; ORDER_COUNT as usize],
|
|
}
|
|
}
|
|
}
|