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124
hbvm/src/softpaging/lookup.rs
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124
hbvm/src/softpaging/lookup.rs
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@ -0,0 +1,124 @@
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//! Address lookup
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use super::{
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addr_extract_index,
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paging::{PageTable, Permission},
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PageSize,
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};
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/// Good result from address split
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pub struct AddrPageLookupOk {
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/// Virtual address
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pub vaddr: u64,
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/// Pointer to the start for perform operation
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pub ptr: *mut u8,
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/// Size to the end of page / end of desired size
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pub size: usize,
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/// Page permission
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pub perm: Permission,
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}
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/// Errornous address split result
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pub struct AddrPageLookupError {
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/// Address of failure
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pub addr: u64,
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/// Requested page size
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pub size: PageSize,
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}
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/// Address splitter into pages
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pub struct AddrPageLookuper {
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/// Current address
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addr: u64,
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/// Size left
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size: usize,
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/// Page table
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pagetable: *const PageTable,
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}
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impl AddrPageLookuper {
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/// Create a new page lookuper
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#[inline]
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pub const fn new(addr: u64, size: usize, pagetable: *const PageTable) -> Self {
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Self {
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addr,
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size,
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pagetable,
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}
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}
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/// Bump address by size X
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pub fn bump(&mut self, page_size: PageSize) {
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self.addr += page_size as u64;
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self.size = self.size.saturating_sub(page_size as _);
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}
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}
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impl Iterator for AddrPageLookuper {
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type Item = Result<AddrPageLookupOk, AddrPageLookupError>;
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fn next(&mut self) -> Option<Self::Item> {
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// The end, everything is fine
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if self.size == 0 {
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return None;
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}
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let (base, perm, size, offset) = 'a: {
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let mut current_pt = self.pagetable;
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// Walk the page table
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for lvl in (0..5).rev() {
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// Get an entry
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unsafe {
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let entry = (*current_pt)
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.table
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.get_unchecked(addr_extract_index(self.addr, lvl));
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let ptr = entry.ptr();
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match entry.permission() {
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// No page → page fault
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Permission::Empty => {
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return Some(Err(AddrPageLookupError {
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addr: self.addr,
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size: PageSize::from_lvl(lvl)?,
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}))
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}
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// Node → proceed waking
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Permission::Node => current_pt = ptr as _,
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// Leaf → return relevant data
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perm => {
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break 'a (
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// Pointer in host memory
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ptr as *mut u8,
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perm,
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PageSize::from_lvl(lvl)?,
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// In-page offset
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addr_extract_index(self.addr, lvl),
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);
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}
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}
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}
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}
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return None; // Reached the end (should not happen)
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};
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// Get available byte count in the selected page with offset
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let avail = (size as usize - offset).clamp(0, self.size);
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self.bump(size);
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Some(Ok(AddrPageLookupOk {
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vaddr: self.addr,
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ptr: unsafe { base.add(offset) }, // Return pointer to the start of region
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size: avail,
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perm,
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}))
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}
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}
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163
hbvm/src/softpaging/mapping.rs
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163
hbvm/src/softpaging/mapping.rs
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@ -0,0 +1,163 @@
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//! Automatic memory mapping
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use {
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super::{
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addr_extract_index,
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paging::{PageTable, Permission, PtEntry, PtPointedData},
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PageSize, SoftPagedMem,
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},
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alloc::boxed::Box,
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derive_more::Display,
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};
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#[cfg(feature = "alloc")]
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impl<'p, A> SoftPagedMem<'p, A> {
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/// Maps host's memory into VM's memory
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///
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/// # Safety
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/// - Your faith in the gods of UB
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/// - Addr-san claims it's fine but who knows is she isn't lying :ferrisSus:
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/// - Alright, Miri-sama is also fine with this, who knows why
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pub unsafe fn map(
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&mut self,
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host: *mut u8,
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target: u64,
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perm: Permission,
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pagesize: PageSize,
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) -> Result<(), MapError> {
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let mut current_pt = self.root_pt;
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// Decide on what level depth are we going
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let lookup_depth = match pagesize {
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PageSize::Size4K => 0,
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PageSize::Size2M => 1,
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PageSize::Size1G => 2,
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};
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// Walk pagetable levels
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for lvl in (lookup_depth + 1..5).rev() {
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let entry = (*current_pt)
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.table
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.get_unchecked_mut(addr_extract_index(target, lvl));
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let ptr = entry.ptr();
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match entry.permission() {
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// Still not on target and already seeing empty entry?
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// No worries! Let's create one (allocates).
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Permission::Empty => {
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// Increase children count
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(*current_pt).childen += 1;
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let table = Box::into_raw(Box::new(PtPointedData {
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pt: PageTable::default(),
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}));
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core::ptr::write(entry, PtEntry::new(table, Permission::Node));
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current_pt = table as _;
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}
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// Continue walking
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Permission::Node => current_pt = ptr as _,
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// There is some entry on place of node
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_ => return Err(MapError::PageOnNode),
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}
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}
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let node = (*current_pt)
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.table
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.get_unchecked_mut(addr_extract_index(target, lookup_depth));
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// Check if node is not mapped
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if node.permission() != Permission::Empty {
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return Err(MapError::AlreadyMapped);
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}
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// Write entry
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(*current_pt).childen += 1;
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core::ptr::write(node, PtEntry::new(host.cast(), perm));
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Ok(())
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}
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/// Unmaps pages from VM's memory
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///
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/// If errors, it only means there is no entry to unmap and in most cases
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/// just should be ignored.
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pub fn unmap(&mut self, addr: u64) -> Result<(), NothingToUnmap> {
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let mut current_pt = self.root_pt;
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let mut page_tables = [core::ptr::null_mut(); 5];
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// Walk page table in reverse
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for lvl in (0..5).rev() {
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let entry = unsafe {
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(*current_pt)
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.table
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.get_unchecked_mut(addr_extract_index(addr, lvl))
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};
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let ptr = entry.ptr();
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match entry.permission() {
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// Nothing is there, throw an error, not critical!
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Permission::Empty => return Err(NothingToUnmap),
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// Node – Save to visited pagetables and continue walking
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Permission::Node => {
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page_tables[lvl as usize] = entry;
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current_pt = ptr as _
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}
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// Page entry – zero it out!
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// Zero page entry is completely valid entry with
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// empty permission - no UB here!
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_ => unsafe {
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core::ptr::write_bytes(entry, 0, 1);
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break;
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},
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}
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}
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// Now walk in order visited page tables
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for entry in page_tables.into_iter() {
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// Level not visited, skip.
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if entry.is_null() {
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continue;
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}
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unsafe {
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let children = &mut (*(*entry).ptr()).pt.childen;
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*children -= 1; // Decrease children count
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// If there are no children, deallocate.
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if *children == 0 {
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let _ = Box::from_raw((*entry).ptr() as *mut PageTable);
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// Zero visited entry
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core::ptr::write_bytes(entry, 0, 1);
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} else {
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break;
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}
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}
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}
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Ok(())
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}
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}
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/// Error mapping
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#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)]
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pub enum MapError {
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/// Entry was already mapped
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#[display(fmt = "There is already a page mapped on specified address")]
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AlreadyMapped,
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/// When walking a page entry was
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/// encounterd.
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#[display(fmt = "There was a page mapped on the way instead of node")]
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PageOnNode,
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}
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/// There was no entry in page table to unmap
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///
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/// No worry, don't panic, nothing bad has happened,
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/// but if you are 120% sure there should be something,
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/// double-check your addresses.
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#[derive(Clone, Copy, Display, Debug)]
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#[display(fmt = "There was no entry to unmap")]
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pub struct NothingToUnmap;
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@ -1,17 +1,19 @@
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//! Platform independent, software paged memory implementation
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use self::lookup::{AddrPageLookupError, AddrPageLookupOk, AddrPageLookuper};
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pub mod lookup;
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pub mod paging;
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#[cfg(feature = "alloc")]
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pub mod mapping;
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use {
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super::{LoadError, Memory, MemoryAccessReason, StoreError},
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core::slice::SliceIndex,
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derive_more::Display,
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paging::{PageTable, Permission},
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};
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#[cfg(feature = "alloc")]
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use {alloc::boxed::Box, paging::PtEntry};
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/// HoleyBytes software paged memory
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#[derive(Clone, Debug)]
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pub struct SoftPagedMem<'p, PfH> {
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@ -173,261 +175,6 @@ impl<'p, PfH: HandlePageFault> SoftPagedMem<'p, PfH> {
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}
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}
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/// Good result from address split
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struct AddrPageLookupOk {
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/// Virtual address
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vaddr: u64,
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/// Pointer to the start for perform operation
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ptr: *mut u8,
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/// Size to the end of page / end of desired size
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size: usize,
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/// Page permission
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perm: Permission,
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}
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/// Errornous address split result
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struct AddrPageLookupError {
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/// Address of failure
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addr: u64,
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/// Requested page size
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size: PageSize,
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}
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/// Address splitter into pages
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struct AddrPageLookuper {
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/// Current address
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addr: u64,
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/// Size left
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size: usize,
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/// Page table
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pagetable: *const PageTable,
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}
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impl AddrPageLookuper {
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/// Create a new page lookuper
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#[inline]
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pub const fn new(addr: u64, size: usize, pagetable: *const PageTable) -> Self {
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Self {
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addr,
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size,
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pagetable,
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}
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}
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/// Bump address by size X
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fn bump(&mut self, page_size: PageSize) {
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self.addr += page_size as u64;
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self.size = self.size.saturating_sub(page_size as _);
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}
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}
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impl Iterator for AddrPageLookuper {
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type Item = Result<AddrPageLookupOk, AddrPageLookupError>;
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fn next(&mut self) -> Option<Self::Item> {
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// The end, everything is fine
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if self.size == 0 {
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return None;
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}
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let (base, perm, size, offset) = 'a: {
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let mut current_pt = self.pagetable;
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// Walk the page table
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for lvl in (0..5).rev() {
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// Get an entry
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unsafe {
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let entry = (*current_pt)
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.table
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.get_unchecked(addr_extract_index(self.addr, lvl));
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let ptr = entry.ptr();
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match entry.permission() {
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// No page → page fault
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Permission::Empty => {
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return Some(Err(AddrPageLookupError {
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addr: self.addr,
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size: PageSize::from_lvl(lvl)?,
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}))
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}
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// Node → proceed waking
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Permission::Node => current_pt = ptr as _,
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|
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// Leaf → return relevant data
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perm => {
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break 'a (
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// Pointer in host memory
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ptr as *mut u8,
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perm,
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PageSize::from_lvl(lvl)?,
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// In-page offset
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addr_extract_index(self.addr, lvl),
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);
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}
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}
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}
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}
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return None; // Reached the end (should not happen)
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};
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|
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// Get available byte count in the selected page with offset
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let avail = (size as usize - offset).clamp(0, self.size);
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self.bump(size);
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|
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Some(Ok(AddrPageLookupOk {
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vaddr: self.addr,
|
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ptr: unsafe { base.add(offset) }, // Return pointer to the start of region
|
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size: avail,
|
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perm,
|
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}))
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}
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}
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#[cfg(feature = "alloc")]
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impl<'p, A> Drop for SoftPagedMem<'p, A> {
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fn drop(&mut self) {
|
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let _ = unsafe { Box::from_raw(self.root_pt) };
|
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}
|
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}
|
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|
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#[cfg(feature = "alloc")]
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impl<'p, A> SoftPagedMem<'p, A> {
|
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/// Maps host's memory into VM's memory
|
||||
///
|
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/// # Safety
|
||||
/// - Your faith in the gods of UB
|
||||
/// - Addr-san claims it's fine but who knows is she isn't lying :ferrisSus:
|
||||
/// - Alright, Miri-sama is also fine with this, who knows why
|
||||
pub unsafe fn map(
|
||||
&mut self,
|
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host: *mut u8,
|
||||
target: u64,
|
||||
perm: Permission,
|
||||
pagesize: PageSize,
|
||||
) -> Result<(), MapError> {
|
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let mut current_pt = self.root_pt;
|
||||
|
||||
// Decide on what level depth are we going
|
||||
let lookup_depth = match pagesize {
|
||||
PageSize::Size4K => 0,
|
||||
PageSize::Size2M => 1,
|
||||
PageSize::Size1G => 2,
|
||||
};
|
||||
|
||||
// Walk pagetable levels
|
||||
for lvl in (lookup_depth + 1..5).rev() {
|
||||
let entry = (*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(target, lvl));
|
||||
|
||||
let ptr = entry.ptr();
|
||||
match entry.permission() {
|
||||
// Still not on target and already seeing empty entry?
|
||||
// No worries! Let's create one (allocates).
|
||||
Permission::Empty => {
|
||||
// Increase children count
|
||||
(*current_pt).childen += 1;
|
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|
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let table = Box::into_raw(Box::new(paging::PtPointedData {
|
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pt: PageTable::default(),
|
||||
}));
|
||||
|
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core::ptr::write(entry, PtEntry::new(table, Permission::Node));
|
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current_pt = table as _;
|
||||
}
|
||||
// Continue walking
|
||||
Permission::Node => current_pt = ptr as _,
|
||||
|
||||
// There is some entry on place of node
|
||||
_ => return Err(MapError::PageOnNode),
|
||||
}
|
||||
}
|
||||
|
||||
let node = (*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(target, lookup_depth));
|
||||
|
||||
// Check if node is not mapped
|
||||
if node.permission() != Permission::Empty {
|
||||
return Err(MapError::AlreadyMapped);
|
||||
}
|
||||
|
||||
// Write entry
|
||||
(*current_pt).childen += 1;
|
||||
core::ptr::write(node, PtEntry::new(host.cast(), perm));
|
||||
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Unmaps pages from VM's memory
|
||||
///
|
||||
/// If errors, it only means there is no entry to unmap and in most cases
|
||||
/// just should be ignored.
|
||||
pub fn unmap(&mut self, addr: u64) -> Result<(), NothingToUnmap> {
|
||||
let mut current_pt = self.root_pt;
|
||||
let mut page_tables = [core::ptr::null_mut(); 5];
|
||||
|
||||
// Walk page table in reverse
|
||||
for lvl in (0..5).rev() {
|
||||
let entry = unsafe {
|
||||
(*current_pt)
|
||||
.table
|
||||
.get_unchecked_mut(addr_extract_index(addr, lvl))
|
||||
};
|
||||
|
||||
let ptr = entry.ptr();
|
||||
match entry.permission() {
|
||||
// Nothing is there, throw an error, not critical!
|
||||
Permission::Empty => return Err(NothingToUnmap),
|
||||
// Node – Save to visited pagetables and continue walking
|
||||
Permission::Node => {
|
||||
page_tables[lvl as usize] = entry;
|
||||
current_pt = ptr as _
|
||||
}
|
||||
// Page entry – zero it out!
|
||||
// Zero page entry is completely valid entry with
|
||||
// empty permission - no UB here!
|
||||
_ => unsafe {
|
||||
core::ptr::write_bytes(entry, 0, 1);
|
||||
break;
|
||||
},
|
||||
}
|
||||
}
|
||||
|
||||
// Now walk in order visited page tables
|
||||
for entry in page_tables.into_iter() {
|
||||
// Level not visited, skip.
|
||||
if entry.is_null() {
|
||||
continue;
|
||||
}
|
||||
|
||||
unsafe {
|
||||
let children = &mut (*(*entry).ptr()).pt.childen;
|
||||
*children -= 1; // Decrease children count
|
||||
|
||||
// If there are no children, deallocate.
|
||||
if *children == 0 {
|
||||
let _ = Box::from_raw((*entry).ptr() as *mut PageTable);
|
||||
|
||||
// Zero visited entry
|
||||
core::ptr::write_bytes(entry, 0, 1);
|
||||
} else {
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Ok(())
|
||||
}
|
||||
}
|
||||
|
||||
/// Extract index in page table on specified level
|
||||
///
|
||||
/// The level shall not be larger than 4, otherwise
|
||||
|
|
@ -462,27 +209,6 @@ impl PageSize {
|
|||
}
|
||||
}
|
||||
|
||||
/// Error mapping
|
||||
#[derive(Clone, Copy, Display, Debug, PartialEq, Eq)]
|
||||
pub enum MapError {
|
||||
/// Entry was already mapped
|
||||
#[display(fmt = "There is already a page mapped on specified address")]
|
||||
AlreadyMapped,
|
||||
/// When walking a page entry was
|
||||
/// encounterd.
|
||||
#[display(fmt = "There was a page mapped on the way instead of node")]
|
||||
PageOnNode,
|
||||
}
|
||||
|
||||
/// There was no entry in page table to unmap
|
||||
///
|
||||
/// No worry, don't panic, nothing bad has happened,
|
||||
/// but if you are 120% sure there should be something,
|
||||
/// double-check your addresses.
|
||||
#[derive(Clone, Copy, Display, Debug)]
|
||||
#[display(fmt = "There was no entry to unmap")]
|
||||
pub struct NothingToUnmap;
|
||||
|
||||
/// Permisison checks
|
||||
pub mod perm_check {
|
||||
use super::paging::Permission;
|
||||
|
|
|
|||
Loading…
Reference in a new issue