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Adding split functionality to VmMapping for optimizing page permission management

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This commit is contained in:
Chen Chengjun
2024-03-11 19:32:18 +08:00
committed by Tate, Hongliang Tian
parent 55054f4835
commit f924eb3694
3 changed files with 187 additions and 99 deletions
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9
kernel/aster-nix/src/syscall/madvise.rs
View File

@ -29,11 +29,10 @@ fn madv_dontneed(start: Vaddr, len: usize) -> Result<()> {
debug_assert!(len % PAGE_SIZE == 0); debug_assert!(len % PAGE_SIZE == 0);
let current = current!(); let current = current!();
let root_vmar = current.root_vmar(); let root_vmar = current.root_vmar();
let vm_mapping = root_vmar.get_vm_mapping(start)?; let advised_range = start..start + len;
// ensure the range is totally in the mapping // `destroy()` interface may require adjustment and replacement afterwards.
debug_assert!(vm_mapping.map_to_addr() <= start); let _ = root_vmar.destroy(advised_range);
debug_assert!(start + len <= vm_mapping.map_to_addr() + vm_mapping.map_size()); Ok(())
vm_mapping.unmap_and_decommit(start..(start + len))
} }
#[repr(i32)] #[repr(i32)]

71
kernel/aster-nix/src/vm/vmar/mod.rs
View File

@ -181,18 +181,26 @@ impl Vmar_ {
Ok(()) Ok(())
} }
// do real protect. The protected range is ensured to be mapped. // Do real protect. The protected range is ensured to be mapped.
fn do_protect_inner(&self, perms: VmPerms, range: Range<usize>) -> Result<()> { fn do_protect_inner(&self, perms: VmPerms, range: Range<usize>) -> Result<()> {
let protect_mappings: Vec<Arc<VmMapping>> = {
let inner = self.inner.lock(); let inner = self.inner.lock();
inner
.vm_mappings
.find(&range)
.into_iter()
.cloned()
.collect()
};
for vm_mapping in inner.vm_mappings.find(&range) { for vm_mapping in protect_mappings {
let vm_mapping_range = vm_mapping.range(); let vm_mapping_range =
debug_assert!(is_intersected(&vm_mapping_range, &range)); vm_mapping.map_to_addr()..(vm_mapping.map_to_addr() + vm_mapping.map_size());
let intersected_range = get_intersected_range(&range, &vm_mapping_range); let intersected_range = get_intersected_range(&range, &vm_mapping_range);
vm_mapping.protect(perms, intersected_range)?; vm_mapping.protect(perms, intersected_range)?;
} }
for child_vmar_ in inner.child_vmar_s.find(&range) { for child_vmar_ in self.inner.lock().child_vmar_s.find(&range) {
let child_vmar_range = child_vmar_.range(); let child_vmar_range = child_vmar_.range();
debug_assert!(is_intersected(&child_vmar_range, &range)); debug_assert!(is_intersected(&child_vmar_range, &range));
let intersected_range = get_intersected_range(&range, &child_vmar_range); let intersected_range = get_intersected_range(&range, &child_vmar_range);
@ -202,7 +210,7 @@ impl Vmar_ {
Ok(()) Ok(())
} }
/// ensure the whole protected range is mapped, that is to say, backed up by a VMO. /// Ensure the whole protected range is mapped, that is to say, backed up by a VMO.
/// Internally, we check whether the range intersects any free region recursively. /// Internally, we check whether the range intersects any free region recursively.
/// If so, the range is not fully mapped. /// If so, the range is not fully mapped.
fn check_protected_range(&self, protected_range: &Range<usize>) -> Result<()> { fn check_protected_range(&self, protected_range: &Range<usize>) -> Result<()> {
@ -265,7 +273,7 @@ impl Vmar_ {
return_errno_with_message!(Errno::EACCES, "page fault addr is not in current vmar"); return_errno_with_message!(Errno::EACCES, "page fault addr is not in current vmar");
} }
/// clear all content of the root vmar /// Clear all content of the root vmar
pub fn clear_root_vmar(&self) -> Result<()> { pub fn clear_root_vmar(&self) -> Result<()> {
debug_assert!(self.is_root_vmar()); debug_assert!(self.is_root_vmar());
if !self.is_root_vmar() { if !self.is_root_vmar() {
@ -366,7 +374,7 @@ impl Vmar_ {
let child_vmar_range = child_vmar_.range(); let child_vmar_range = child_vmar_.range();
debug_assert!(is_intersected(&child_vmar_range, range)); debug_assert!(is_intersected(&child_vmar_range, range));
if range.start <= child_vmar_range.start && child_vmar_range.end <= range.end { if range.start <= child_vmar_range.start && child_vmar_range.end <= range.end {
// child vmar is totolly in the range // Child vmar is totally in the range.
continue; continue;
} }
return_errno_with_message!( return_errno_with_message!(
@ -404,7 +412,7 @@ impl Vmar_ {
let read_start = self.base + offset; let read_start = self.base + offset;
let read_end = buf.len() + read_start; let read_end = buf.len() + read_start;
let read_range = read_start..read_end; let read_range = read_start..read_end;
// if the read range is in child vmar // If the read range is in child vmar.
let inner = self.inner.lock(); let inner = self.inner.lock();
for child_vmar_ in inner.child_vmar_s.find(&read_range) { for child_vmar_ in inner.child_vmar_s.find(&read_range) {
let child_vmar_range = child_vmar_.range(); let child_vmar_range = child_vmar_.range();
@ -414,7 +422,7 @@ impl Vmar_ {
} }
} }
// if the read range is in mapped vmo // If the read range is in mapped vmo.
for vm_mapping in inner.vm_mappings.find(&read_range) { for vm_mapping in inner.vm_mappings.find(&read_range) {
let vm_mapping_range = vm_mapping.range(); let vm_mapping_range = vm_mapping.range();
if vm_mapping_range.start <= read_start && read_end <= vm_mapping_range.end { if vm_mapping_range.start <= read_start && read_end <= vm_mapping_range.end {
@ -439,7 +447,7 @@ impl Vmar_ {
.ok_or_else(|| Error::with_message(Errno::EFAULT, "Arithmetic Overflow"))?; .ok_or_else(|| Error::with_message(Errno::EFAULT, "Arithmetic Overflow"))?;
let write_range = write_start..write_end; let write_range = write_start..write_end;
// if the write range is in child vmar // If the write range is in child vmar.
let inner = self.inner.lock(); let inner = self.inner.lock();
for child_vmar_ in inner.child_vmar_s.find(&write_range) { for child_vmar_ in inner.child_vmar_s.find(&write_range) {
let child_vmar_range = child_vmar_.range(); let child_vmar_range = child_vmar_.range();
@ -449,7 +457,7 @@ impl Vmar_ {
} }
} }
// if the write range is in mapped vmo // If the write range is in mapped vmo.
for vm_mapping in inner.vm_mappings.find(&write_range) { for vm_mapping in inner.vm_mappings.find(&write_range) {
let vm_mapping_range = vm_mapping.range(); let vm_mapping_range = vm_mapping.range();
if vm_mapping_range.start <= write_start && write_end <= vm_mapping_range.end { if vm_mapping_range.start <= write_start && write_end <= vm_mapping_range.end {
@ -462,7 +470,7 @@ impl Vmar_ {
return_errno_with_message!(Errno::EACCES, "write range is not backed up by a vmo"); return_errno_with_message!(Errno::EACCES, "write range is not backed up by a vmo");
} }
/// allocate a child vmar_. /// Allocate a child vmar_.
pub fn alloc_child_vmar( pub fn alloc_child_vmar(
self: &Arc<Self>, self: &Arc<Self>,
child_vmar_offset: Option<usize>, child_vmar_offset: Option<usize>,
@ -504,8 +512,8 @@ impl Vmar_ {
Ok(child_vmar_) Ok(child_vmar_)
} }
/// find a free region for child vmar or vmo. /// Find a free region for child vmar or vmo.
/// returns (region base addr, child real offset) /// Returns (region base addr, child real offset).
fn find_free_region_for_child( fn find_free_region_for_child(
&self, &self,
child_offset: Option<Vaddr>, child_offset: Option<Vaddr>,
@ -526,7 +534,7 @@ impl Vmar_ {
} }
} }
} else { } else {
// else, we find a free region that can satisfy the length and align requirement. // Else, we find a free region that can satisfy the length and align requirement.
// Here, we use a simple brute-force algorithm to find the first free range that can satisfy. // Here, we use a simple brute-force algorithm to find the first free range that can satisfy.
// FIXME: A randomized algorithm may be more efficient. // FIXME: A randomized algorithm may be more efficient.
for (region_base, free_region) in &inner.free_regions { for (region_base, free_region) in &inner.free_regions {
@ -568,12 +576,12 @@ impl Vmar_ {
Ok(()) Ok(())
} }
/// returns the attached vm_space /// Returns the attached `VmSpace`.
pub(super) fn vm_space(&self) -> &VmSpace { pub(super) fn vm_space(&self) -> &VmSpace {
&self.vm_space &self.vm_space
} }
/// map a vmo to this vmar /// Map a vmo to this vmar.
pub fn add_mapping(&self, mapping: Arc<VmMapping>) { pub fn add_mapping(&self, mapping: Arc<VmMapping>) {
self.inner self.inner
.lock() .lock()
@ -589,18 +597,18 @@ impl Vmar_ {
align: usize, align: usize,
can_overwrite: bool, can_overwrite: bool,
) -> Result<Vaddr> { ) -> Result<Vaddr> {
trace!("allocate free region, vmo_size = 0x{:x}, map_size = 0x{:x}, offset = {:x?}, align = 0x{:x}, can_ovewrite = {}", vmo_size, size, offset, align, can_overwrite); trace!("allocate free region, vmo_size = 0x{:x}, map_size = 0x{:x}, offset = {:x?}, align = 0x{:x}, can_overwrite = {}", vmo_size, size, offset, align, can_overwrite);
let map_size = size.max(vmo_size); let map_size = size.max(vmo_size);
if can_overwrite { if can_overwrite {
let mut inner = self.inner.lock(); let mut inner = self.inner.lock();
// if can_overwrite, the offset is ensured not to be None // If can_overwrite, the offset is ensured not to be None.
let offset = offset.ok_or(Error::with_message( let offset = offset.ok_or(Error::with_message(
Errno::EINVAL, Errno::EINVAL,
"offset cannot be None since can overwrite is set", "offset cannot be None since can overwrite is set",
))?; ))?;
let map_range = offset..(offset + map_size); let map_range = offset..(offset + map_size);
// If can overwrite, the vmo can cross multiple free regions. We will split each free regions that intersect with the vmo // If can overwrite, the vmo can cross multiple free regions. We will split each free regions that intersect with the vmo.
let mut split_regions = Vec::new(); let mut split_regions = Vec::new();
for free_region in inner.free_regions.find(&map_range) { for free_region in inner.free_regions.find(&map_range) {
@ -622,7 +630,7 @@ impl Vmar_ {
self.trim_existing_mappings(map_range)?; self.trim_existing_mappings(map_range)?;
Ok(offset) Ok(offset)
} else { } else {
// Otherwise, the vmo in a single region // Otherwise, the vmo in a single region.
let (free_region_base, offset) = let (free_region_base, offset) =
self.find_free_region_for_child(offset, map_size, align)?; self.find_free_region_for_child(offset, map_size, align)?;
let mut inner = self.inner.lock(); let mut inner = self.inner.lock();
@ -666,7 +674,7 @@ impl Vmar_ {
self.new_cow(None) self.new_cow(None)
} }
/// Create a new vmar by creating cow child for all mapped vmos /// Create a new vmar by creating cow child for all mapped vmos.
fn new_cow(&self, parent: Option<&Arc<Vmar_>>) -> Result<Arc<Self>> { fn new_cow(&self, parent: Option<&Arc<Vmar_>>) -> Result<Arc<Self>> {
let new_vmar_ = { let new_vmar_ = {
let vmar_inner = VmarInner::new(); let vmar_inner = VmarInner::new();
@ -681,7 +689,7 @@ impl Vmar_ {
}; };
let inner = self.inner.lock(); let inner = self.inner.lock();
// clone free regions // Clone free regions.
for (free_region_base, free_region) in &inner.free_regions { for (free_region_base, free_region) in &inner.free_regions {
new_vmar_ new_vmar_
.inner .inner
@ -690,7 +698,7 @@ impl Vmar_ {
.insert(*free_region_base, free_region.clone()); .insert(*free_region_base, free_region.clone());
} }
// clone child vmars // Clone child vmars.
for (child_vmar_base, child_vmar_) in &inner.child_vmar_s { for (child_vmar_base, child_vmar_) in &inner.child_vmar_s {
let new_child_vmar = child_vmar_.new_cow(Some(&new_vmar_))?; let new_child_vmar = child_vmar_.new_cow(Some(&new_vmar_))?;
new_vmar_ new_vmar_
@ -700,7 +708,7 @@ impl Vmar_ {
.insert(*child_vmar_base, new_child_vmar); .insert(*child_vmar_base, new_child_vmar);
} }
// clone vm mappings // Clone vm mappings.
for (vm_mapping_base, vm_mapping) in &inner.vm_mappings { for (vm_mapping_base, vm_mapping) in &inner.vm_mappings {
let new_mapping = Arc::new(vm_mapping.new_cow(&new_vmar_)?); let new_mapping = Arc::new(vm_mapping.new_cow(&new_vmar_)?);
new_vmar_ new_vmar_
@ -739,7 +747,8 @@ impl<R> Vmar<R> {
self.0.size self.0.size
} }
/// get a mapped vmo /// Get mapped vmo at given offset.
/// TODO: improve the searching algorithm.
pub fn get_vm_mapping(&self, offset: Vaddr) -> Result<Arc<VmMapping>> { pub fn get_vm_mapping(&self, offset: Vaddr) -> Result<Arc<VmMapping>> {
let rights = Rights::all(); let rights = Rights::all();
self.check_rights(rights)?; self.check_rights(rights)?;
@ -775,7 +784,7 @@ impl FreeRegion {
self.range.end - self.range.start self.range.end - self.range.start
} }
/// allocate a range in this free region. /// Allocate a range in this free region.
/// The range is ensured to be contained in current region before call this function. /// The range is ensured to be contained in current region before call this function.
/// The return vector contains regions that are not allocated. Since the allocate_range can be /// The return vector contains regions that are not allocated. Since the allocate_range can be
/// in the middle of a free region, the original region may be split as at most two regions. /// in the middle of a free region, the original region may be split as at most two regions.
@ -799,13 +808,13 @@ impl FreeRegion {
} }
} }
/// determine whether two ranges are intersected. /// Determine whether two ranges are intersected.
/// returns zero if one of the ranges has a length of 0 /// returns false if one of the ranges has a length of 0
pub fn is_intersected(range1: &Range<usize>, range2: &Range<usize>) -> bool { pub fn is_intersected(range1: &Range<usize>, range2: &Range<usize>) -> bool {
range1.start.max(range2.start) < range1.end.min(range2.end) range1.start.max(range2.start) < range1.end.min(range2.end)
} }
/// get the intersection range of two ranges. /// Get the intersection range of two ranges.
/// The two ranges should be ensured to be intersected. /// The two ranges should be ensured to be intersected.
pub fn get_intersected_range(range1: &Range<usize>, range2: &Range<usize>) -> Range<usize> { pub fn get_intersected_range(range1: &Range<usize>, range2: &Range<usize>) -> Range<usize> {
debug_assert!(is_intersected(range1, range2)); debug_assert!(is_intersected(range1, range2));

204
kernel/aster-nix/src/vm/vmar/vm_mapping.rs
View File

@ -17,7 +17,7 @@ use crate::{
/// A VmMapping represents mapping a vmo into a vmar. /// A VmMapping represents mapping a vmo into a vmar.
/// A vmar can has multiple VmMappings, which means multiple vmos are mapped to a vmar. /// A vmar can has multiple VmMappings, which means multiple vmos are mapped to a vmar.
/// A vmo can also contain multiple VmMappings, which means a vmo can be mapped to multiple vmars. /// A vmo can also contain multiple VmMappings, which means a vmo can be mapped to multiple vmars.
/// The reltionship between Vmar and Vmo is M:N. /// The relationship between Vmar and Vmo is M:N.
pub struct VmMapping { pub struct VmMapping {
inner: Mutex<VmMappingInner>, inner: Mutex<VmMappingInner>,
/// The parent vmar. The parent should always point to a valid vmar. /// The parent vmar. The parent should always point to a valid vmar.
@ -51,10 +51,9 @@ struct VmMappingInner {
is_destroyed: bool, is_destroyed: bool,
/// The pages already mapped. The key is the page index in vmo. /// The pages already mapped. The key is the page index in vmo.
mapped_pages: BTreeSet<usize>, mapped_pages: BTreeSet<usize>,
/// The permission of each page. The key is the page index in vmo. /// The permission of pages in the mapping.
/// This map can be filled when mapping a vmo to vmar and can be modified when call mprotect. /// All pages within the same VmMapping have the same permission.
/// We keep the options in case the page is not committed(or create copy on write mappings) and will further need these options. perm: VmPerm,
page_perms: BTreeMap<usize, VmPerm>,
} }
impl Interval<usize> for Arc<VmMapping> { impl Interval<usize> for Arc<VmMapping> {
@ -90,23 +89,13 @@ impl VmMapping {
map_to_addr + size map_to_addr + size
); );
let page_perms = {
let mut page_perms = BTreeMap::new();
let perm = VmPerm::from(perms);
let page_idx_range = get_page_idx_range(&(vmo_offset..vmo_offset + size));
for page_idx in page_idx_range {
page_perms.insert(page_idx, perm);
}
page_perms
};
let vm_mapping_inner = VmMappingInner { let vm_mapping_inner = VmMappingInner {
vmo_offset, vmo_offset,
map_size: size, map_size: size,
map_to_addr, map_to_addr,
is_destroyed: false, is_destroyed: false,
mapped_pages: BTreeSet::new(), mapped_pages: BTreeSet::new(),
page_perms, perm: VmPerm::from(perms),
}; };
Ok(Self { Ok(Self {
@ -116,6 +105,28 @@ impl VmMapping {
}) })
} }
/// Build a new VmMapping based on part of current `VmMapping`.
/// The mapping range of the new mapping must be contained in the full mapping.
///
/// Note: Since such new mappings will intersect with the current mapping,
/// making sure that when adding the new mapping into a Vmar, the current mapping in the Vmar will be removed.
fn clone_partial(
&self,
range: Range<usize>,
new_perm: Option<VmPerm>,
) -> Result<Arc<VmMapping>> {
let partial_mapping = Arc::new(self.try_clone()?);
// Adjust the mapping range and the permission.
{
let mut inner = partial_mapping.inner.lock();
inner.shrink_to(range);
if let Some(perm) = new_perm {
inner.perm = perm;
}
}
Ok(partial_mapping)
}
pub fn vmo(&self) -> &Vmo<Rights> { pub fn vmo(&self) -> &Vmo<Rights> {
&self.vmo &self.vmo
} }
@ -190,17 +201,6 @@ impl VmMapping {
self.inner.lock().unmap(vm_space, range, may_destroy) self.inner.lock().unmap(vm_space, range, may_destroy)
} }
pub fn unmap_and_decommit(&self, range: Range<usize>) -> Result<()> {
self.unmap(&range, false)?;
let vmo_range = {
let map_to_addr = self.map_to_addr();
let vmo_offset = self.vmo_offset();
(range.start - map_to_addr + vmo_offset)..(range.end - map_to_addr + vmo_offset)
};
self.vmo.decommit(vmo_range)?;
Ok(())
}
pub fn is_destroyed(&self) -> bool { pub fn is_destroyed(&self) -> bool {
self.inner.lock().is_destroyed self.inner.lock().is_destroyed
} }
@ -233,12 +233,28 @@ impl VmMapping {
self.map_one_page(page_idx, frame, is_readonly) self.map_one_page(page_idx, frame, is_readonly)
} }
pub(super) fn protect(&self, perms: VmPerms, range: Range<usize>) -> Result<()> { /// Protect a specified range of pages in the mapping to the target perms.
let rights = Rights::from(perms); /// The VmMapping will split to maintain its property.
///
/// Since this method will modify the `vm_mappings` in the vmar,
/// it should not be called during the direct iteration of the `vm_mappings`.
pub(super) fn protect(&self, new_perms: VmPerms, range: Range<usize>) -> Result<()> {
// If `new_perms` is equal to `old_perms`, `protect()` will not modify any permission in the VmMapping.
let old_perms = VmPerms::from(self.inner.lock().perm);
if old_perms == new_perms {
return Ok(());
}
let rights = Rights::from(new_perms);
self.vmo().check_rights(rights)?; self.vmo().check_rights(rights)?;
// Protect permission for the perm in the VmMapping.
self.protect_with_subdivision(&range, VmPerm::from(new_perms))?;
// Protect permission in the VmSpace.
let vmar = self.parent.upgrade().unwrap(); let vmar = self.parent.upgrade().unwrap();
let vm_space = vmar.vm_space(); let vm_space = vmar.vm_space();
self.inner.lock().protect(vm_space, perms, range) self.inner.lock().protect(vm_space, new_perms, range)?;
Ok(())
} }
pub(super) fn new_cow(&self, new_parent: &Arc<Vmar_>) -> Result<VmMapping> { pub(super) fn new_cow(&self, new_parent: &Arc<Vmar_>) -> Result<VmMapping> {
@ -258,7 +274,7 @@ impl VmMapping {
map_to_addr: inner.map_to_addr, map_to_addr: inner.map_to_addr,
is_destroyed: inner.is_destroyed, is_destroyed: inner.is_destroyed,
mapped_pages: BTreeSet::new(), mapped_pages: BTreeSet::new(),
page_perms: inner.page_perms.clone(), perm: inner.perm,
} }
}; };
@ -273,6 +289,63 @@ impl VmMapping {
self.map_to_addr()..self.map_to_addr() + self.map_size() self.map_to_addr()..self.map_to_addr() + self.map_size()
} }
/// Protect the current `VmMapping` to enforce new permissions within a specified range.
///
/// Due to the property of `VmMapping`, this operation may require subdividing the current
/// `VmMapping`. In this condition, it will generate a new `VmMapping` with the specified `perm` to protect the
/// target range, as well as additional `VmMappings` to preserve the mappings in the remaining ranges.
///
/// There are four conditions:
/// 1. |--------old perm--------| -> |-old-| + |------new------|
/// 2. |--------old perm--------| -> |-new-| + |------old------|
/// 3. |--------old perm--------| -> |-old-| + |-new-| + |-old-|
/// 4. |--------old perm--------| -> |---------new perm--------|
///
/// Generally, this function is only used in `protect()` method.
/// This method modifies the parent `Vmar` in the end if subdividing is required.
/// It removes current mapping and add splitted mapping to the Vmar.
fn protect_with_subdivision(&self, intersect_range: &Range<usize>, perm: VmPerm) -> Result<()> {
let mut additional_mappings = Vec::new();
let range = self.range();
// Condition 4, the `additional_mappings` will be empty.
if range.start == intersect_range.start && range.end == intersect_range.end {
self.inner.lock().perm = perm;
return Ok(());
}
// Condition 1 or 3, which needs an additional new VmMapping with range (range.start..intersect_range.start)
if range.start < intersect_range.start {
let additional_left_mapping =
self.clone_partial(range.start..intersect_range.start, None)?;
additional_mappings.push(additional_left_mapping);
}
// Condition 2 or 3, which needs an additional new VmMapping with range (intersect_range.end..range.end).
if range.end > intersect_range.end {
let additional_right_mapping =
self.clone_partial(intersect_range.end..range.end, None)?;
additional_mappings.push(additional_right_mapping);
}
// The protected VmMapping must exist and its range is `intersect_range`.
let protected_mapping = self.clone_partial(intersect_range.clone(), Some(perm))?;
// Begin to modify the `Vmar`.
let vmar = self.parent.upgrade().unwrap();
let mut vmar_inner = vmar.inner.lock();
// Remove the original mapping.
vmar_inner.vm_mappings.remove(&self.map_to_addr());
// Add protected mappings to the vmar.
vmar_inner
.vm_mappings
.insert(protected_mapping.map_to_addr(), protected_mapping);
// Add additional mappings to the vmar.
for mapping in additional_mappings {
vmar_inner
.vm_mappings
.insert(mapping.map_to_addr(), mapping);
}
Ok(())
}
/// Trim a range from the mapping. /// Trim a range from the mapping.
/// There are several cases. /// There are several cases.
/// 1. the trim_range is totally in the mapping. Then the mapping will split as two mappings. /// 1. the trim_range is totally in the mapping. Then the mapping will split as two mappings.
@ -294,7 +367,7 @@ impl VmMapping {
return Ok(()); return Ok(());
} }
if trim_range.start <= map_to_addr && trim_range.end >= map_to_addr + map_size { if trim_range.start <= map_to_addr && trim_range.end >= map_to_addr + map_size {
// fast path: the whole mapping was trimed // Fast path: the whole mapping was trimed.
self.unmap(trim_range, true)?; self.unmap(trim_range, true)?;
mappings_to_remove.insert(map_to_addr); mappings_to_remove.insert(map_to_addr);
return Ok(()); return Ok(());
@ -302,20 +375,20 @@ impl VmMapping {
if trim_range.start <= range.start { if trim_range.start <= range.start {
mappings_to_remove.insert(map_to_addr); mappings_to_remove.insert(map_to_addr);
if trim_range.end <= range.end { if trim_range.end <= range.end {
// overlap vm_mapping from left // Overlap vm_mapping from left.
let new_map_addr = self.trim_left(trim_range.end)?; let new_map_addr = self.trim_left(trim_range.end)?;
mappings_to_append.insert(new_map_addr, self.clone()); mappings_to_append.insert(new_map_addr, self.clone());
} else { } else {
// the mapping was totally destroyed // The mapping was totally destroyed.
} }
} else { } else {
if trim_range.end <= range.end { if trim_range.end <= range.end {
// the trim range was totally inside the old mapping // The trim range was totally inside the old mapping.
let another_mapping = Arc::new(self.try_clone()?); let another_mapping = Arc::new(self.try_clone()?);
let another_map_to_addr = another_mapping.trim_left(trim_range.end)?; let another_map_to_addr = another_mapping.trim_left(trim_range.end)?;
mappings_to_append.insert(another_map_to_addr, another_mapping); mappings_to_append.insert(another_map_to_addr, another_mapping);
} else { } else {
// overlap vm_mapping from right // Overlap vm_mapping from right.
} }
self.trim_right(trim_range.start)?; self.trim_right(trim_range.start)?;
} }
@ -323,14 +396,14 @@ impl VmMapping {
Ok(()) Ok(())
} }
/// trim the mapping from left to a new address. /// Trim the mapping from left to a new address.
fn trim_left(&self, vaddr: Vaddr) -> Result<Vaddr> { fn trim_left(&self, vaddr: Vaddr) -> Result<Vaddr> {
let vmar = self.parent.upgrade().unwrap(); let vmar = self.parent.upgrade().unwrap();
let vm_space = vmar.vm_space(); let vm_space = vmar.vm_space();
self.inner.lock().trim_left(vm_space, vaddr) self.inner.lock().trim_left(vm_space, vaddr)
} }
/// trim the mapping from right to a new address. /// Trim the mapping from right to a new address.
fn trim_right(&self, vaddr: Vaddr) -> Result<Vaddr> { fn trim_right(&self, vaddr: Vaddr) -> Result<Vaddr> {
let vmar = self.parent.upgrade().unwrap(); let vmar = self.parent.upgrade().unwrap();
let vm_space = vmar.vm_space(); let vm_space = vmar.vm_space();
@ -354,7 +427,7 @@ impl VmMappingInner {
let map_addr = self.page_map_addr(page_idx); let map_addr = self.page_map_addr(page_idx);
let vm_perm = { let vm_perm = {
let mut perm = *self.page_perms.get(&page_idx).unwrap(); let mut perm = self.perm;
if is_readonly { if is_readonly {
debug_assert!(vmo.is_cow_child()); debug_assert!(vmo.is_cow_child());
perm -= VmPerm::W; perm -= VmPerm::W;
@ -369,7 +442,7 @@ impl VmMappingInner {
options options
}; };
// cow child allows unmapping the mapped page // Cow child allows unmapping the mapped page.
if vmo.is_cow_child() && vm_space.is_mapped(map_addr) { if vmo.is_cow_child() && vm_space.is_mapped(map_addr) {
vm_space.unmap(&(map_addr..(map_addr + PAGE_SIZE))).unwrap(); vm_space.unmap(&(map_addr..(map_addr + PAGE_SIZE))).unwrap();
} }
@ -389,7 +462,7 @@ impl VmMappingInner {
Ok(()) Ok(())
} }
/// Unmap pages in the range /// Unmap pages in the range.
fn unmap(&mut self, vm_space: &VmSpace, range: &Range<usize>, may_destroy: bool) -> Result<()> { fn unmap(&mut self, vm_space: &VmSpace, range: &Range<usize>, may_destroy: bool) -> Result<()> {
let map_to_addr = self.map_to_addr; let map_to_addr = self.map_to_addr;
let vmo_map_range = (range.start - map_to_addr + self.vmo_offset) let vmo_map_range = (range.start - map_to_addr + self.vmo_offset)
@ -405,7 +478,7 @@ impl VmMappingInner {
} }
fn page_map_addr(&self, page_idx: usize) -> usize { fn page_map_addr(&self, page_idx: usize) -> usize {
page_idx * PAGE_SIZE - self.vmo_offset + self.map_to_addr page_idx * PAGE_SIZE + self.map_to_addr - self.vmo_offset
} }
pub(super) fn protect( pub(super) fn protect(
@ -420,11 +493,9 @@ impl VmMappingInner {
let end_page = (range.end - self.map_to_addr + self.vmo_offset) / PAGE_SIZE; let end_page = (range.end - self.map_to_addr + self.vmo_offset) / PAGE_SIZE;
let perm = VmPerm::from(perms); let perm = VmPerm::from(perms);
for page_idx in start_page..end_page { for page_idx in start_page..end_page {
self.page_perms.insert(page_idx, perm);
let page_addr = self.page_map_addr(page_idx); let page_addr = self.page_map_addr(page_idx);
if vm_space.is_mapped(page_addr) { if vm_space.is_mapped(page_addr) {
// if the page is already mapped, we will modify page table // If the page is already mapped, we will modify page table
let perm = VmPerm::from(perms);
let page_range = page_addr..(page_addr + PAGE_SIZE); let page_range = page_addr..(page_addr + PAGE_SIZE);
vm_space.protect(&page_range, perm)?; vm_space.protect(&page_range, perm)?;
} }
@ -432,7 +503,7 @@ impl VmMappingInner {
Ok(()) Ok(())
} }
/// trim the mapping from left to a new address. /// Trim the mapping from left to a new address.
fn trim_left(&mut self, vm_space: &VmSpace, vaddr: Vaddr) -> Result<Vaddr> { fn trim_left(&mut self, vm_space: &VmSpace, vaddr: Vaddr) -> Result<Vaddr> {
trace!( trace!(
"trim left: range: {:x?}, vaddr = 0x{:x}", "trim left: range: {:x?}, vaddr = 0x{:x}",
@ -448,7 +519,6 @@ impl VmMappingInner {
self.vmo_offset += trim_size; self.vmo_offset += trim_size;
self.map_size -= trim_size; self.map_size -= trim_size;
for page_idx in old_vmo_offset / PAGE_SIZE..self.vmo_offset / PAGE_SIZE { for page_idx in old_vmo_offset / PAGE_SIZE..self.vmo_offset / PAGE_SIZE {
self.page_perms.remove(&page_idx);
if self.mapped_pages.remove(&page_idx) { if self.mapped_pages.remove(&page_idx) {
let _ = self.unmap_one_page(vm_space, page_idx); let _ = self.unmap_one_page(vm_space, page_idx);
} }
@ -456,7 +526,7 @@ impl VmMappingInner {
Ok(self.map_to_addr) Ok(self.map_to_addr)
} }
/// trim the mapping from right to a new address. /// Trim the mapping from right to a new address.
fn trim_right(&mut self, vm_space: &VmSpace, vaddr: Vaddr) -> Result<Vaddr> { fn trim_right(&mut self, vm_space: &VmSpace, vaddr: Vaddr) -> Result<Vaddr> {
trace!( trace!(
"trim right: range: {:x?}, vaddr = 0x{:x}", "trim right: range: {:x?}, vaddr = 0x{:x}",
@ -468,24 +538,34 @@ impl VmMappingInner {
let page_idx_range = (vaddr - self.map_to_addr + self.vmo_offset) / PAGE_SIZE let page_idx_range = (vaddr - self.map_to_addr + self.vmo_offset) / PAGE_SIZE
..(self.map_size + self.vmo_offset) / PAGE_SIZE; ..(self.map_size + self.vmo_offset) / PAGE_SIZE;
for page_idx in page_idx_range { for page_idx in page_idx_range {
self.page_perms.remove(&page_idx);
let _ = self.unmap_one_page(vm_space, page_idx); let _ = self.unmap_one_page(vm_space, page_idx);
} }
self.map_size = vaddr - self.map_to_addr; self.map_size = vaddr - self.map_to_addr;
Ok(self.map_to_addr) Ok(self.map_to_addr)
} }
/// Shrink the current `VmMapping` to the new range.
/// The new range must be contained in the old range.
fn shrink_to(&mut self, new_range: Range<usize>) {
debug_assert!(self.map_to_addr <= new_range.start);
debug_assert!(self.map_to_addr + self.map_size >= new_range.end);
self.vmo_offset += new_range.start - self.map_to_addr;
self.map_to_addr = new_range.start;
self.map_size = new_range.end - new_range.start;
}
fn range(&self) -> Range<usize> { fn range(&self) -> Range<usize> {
self.map_to_addr..self.map_to_addr + self.map_size self.map_to_addr..self.map_to_addr + self.map_size
} }
fn check_perm(&self, page_idx: &usize, perm: &VmPerm) -> Result<()> { fn check_perm(&self, page_idx: &usize, perm: &VmPerm) -> Result<()> {
let page_perm = self // Check if the page is in current VmMapping.
.page_perms if page_idx * PAGE_SIZE < self.vmo_offset
.get(page_idx) || (page_idx + 1) * PAGE_SIZE > self.vmo_offset + self.map_size
.ok_or(Error::with_message(Errno::EINVAL, "invalid page idx"))?; {
return_errno_with_message!(Errno::EINVAL, "invalid page idx");
if !page_perm.contains(*perm) { }
if !self.perm.contains(*perm) {
return_errno_with_message!(Errno::EACCES, "perm check fails"); return_errno_with_message!(Errno::EACCES, "perm check fails");
} }
@ -609,9 +689,9 @@ impl<R1, R2> VmarMapOptions<R1, R2> {
Ok(map_to_addr) Ok(map_to_addr)
} }
/// check whether all options are valid /// Check whether all options are valid.
fn check_options(&self) -> Result<()> { fn check_options(&self) -> Result<()> {
// check align // Check align.
debug_assert!(self.align % PAGE_SIZE == 0); debug_assert!(self.align % PAGE_SIZE == 0);
debug_assert!(self.align.is_power_of_two()); debug_assert!(self.align.is_power_of_two());
if self.align % PAGE_SIZE != 0 || !self.align.is_power_of_two() { if self.align % PAGE_SIZE != 0 || !self.align.is_power_of_two() {
@ -632,16 +712,16 @@ impl<R1, R2> VmarMapOptions<R1, R2> {
Ok(()) Ok(())
} }
/// check whether the vmperm is subset of vmo rights /// Check whether the vmperm is subset of vmo rights.
fn check_perms(&self) -> Result<()> { fn check_perms(&self) -> Result<()> {
let perm_rights = Rights::from(self.perms); let perm_rights = Rights::from(self.perms);
self.vmo.check_rights(perm_rights) self.vmo.check_rights(perm_rights)
} }
/// check whether the vmo will overwrite with any existing vmo or vmar /// Check whether the vmo will overwrite with any existing vmo or vmar.
fn check_overwrite(&self) -> Result<()> { fn check_overwrite(&self) -> Result<()> {
if self.can_overwrite { if self.can_overwrite {
// if can_overwrite is set, the offset cannot be None // If `can_overwrite` is set, the offset cannot be None.
debug_assert!(self.offset.is_some()); debug_assert!(self.offset.is_some());
if self.offset.is_none() { if self.offset.is_none() {
return_errno_with_message!( return_errno_with_message!(
@ -651,12 +731,12 @@ impl<R1, R2> VmarMapOptions<R1, R2> {
} }
} }
if self.offset.is_none() { if self.offset.is_none() {
// if does not specify the offset, we assume the map can always find suitable free region. // If does not specify the offset, we assume the map can always find suitable free region.
// FIXME: is this always true? // FIXME: is this always true?
return Ok(()); return Ok(());
} }
let offset = self.offset.unwrap(); let offset = self.offset.unwrap();
// we should spare enough space at least for the whole vmo // We should spare enough space at least for the whole vmo.
let size = self.size.max(self.vmo.size()); let size = self.size.max(self.vmo.size());
let vmo_range = offset..(offset + size); let vmo_range = offset..(offset + size);
self.parent self.parent