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Refactor Vmar and VmMapping.

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Co-authored-by: Zhang Junyang <junyang@stu.pku.edu.cn>
This commit is contained in:
Wang Siyuan
2024-11-09 01:44:11 +00:00
committed by Tate, Hongliang Tian
parent e453649d78
commit 4ea3e49788
12 changed files with 782 additions and 1272 deletions
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38
kernel/src/process/process_vm/heap.rs
View File

@ -34,21 +34,33 @@ impl Heap {
}
}
/// Inits and maps the heap Vmo
pub(super) fn alloc_and_map_vmo(&self, root_vmar: &Vmar<Full>) -> Result<()> {
/// Initializes and maps the heap virtual memory.
pub(super) fn alloc_and_map_vm(&self, root_vmar: &Vmar<Full>) -> Result<()> {
let vmar_map_options = {
let perms = VmPerms::READ | VmPerms::WRITE;
root_vmar
// FIXME: Our current implementation of mapping resize cannot move
// existing mappings within the new range, which may cause the resize
// operation to fail. Therefore, if there are already mappings within
// the heap expansion range, the brk operation will fail.
.new_map(PAGE_SIZE, perms)
.unwrap()
.offset(self.base)
};
vmar_map_options.build()?;
// If we touch another mapped range when we are trying to expand the
// heap, we fail.
//
// So a simple solution is to reserve enough space for the heap by
// mapping without any permissions and allow it to be overwritten
// later by `brk`. New mappings from `mmap` that overlaps this range
// may be moved to another place.
let vmar_reserve_options = {
let perms = VmPerms::empty();
root_vmar
.new_map(USER_HEAP_SIZE_LIMIT - PAGE_SIZE, perms)
.unwrap()
.offset(self.base + PAGE_SIZE)
};
vmar_reserve_options.build()?;
self.set_uninitialized();
Ok(())
}
@ -63,14 +75,24 @@ impl Heap {
return_errno_with_message!(Errno::ENOMEM, "heap size limit was met.");
}
let current_heap_end = self.current_heap_end.load(Ordering::Acquire);
if new_heap_end <= current_heap_end {
// FIXME: should we allow shrink current user heap?
return Ok(current_heap_end);
}
let old_size = (current_heap_end - self.base).align_up(PAGE_SIZE);
let new_size = (new_heap_end - self.base).align_up(PAGE_SIZE);
let current_heap_end = current_heap_end.align_up(PAGE_SIZE);
let new_heap_end = new_heap_end.align_up(PAGE_SIZE);
// Remove the reserved space.
root_vmar.remove_mapping(current_heap_end..new_heap_end)?;
let old_size = current_heap_end - self.base;
let new_size = new_heap_end - self.base;
// Expand the heap.
root_vmar.resize_mapping(self.base, old_size, new_size)?;
self.current_heap_end.store(new_heap_end, Ordering::Release);
Ok(new_heap_end)
}

4
kernel/src/process/process_vm/mod.rs
View File

@ -84,7 +84,7 @@ impl ProcessVm {
let root_vmar = Vmar::<Full>::new_root();
let init_stack = InitStack::new();
let heap = Heap::new();
heap.alloc_and_map_vmo(&root_vmar).unwrap();
heap.alloc_and_map_vm(&root_vmar).unwrap();
Self {
root_vmar,
heap,
@ -136,6 +136,6 @@ impl ProcessVm {
/// Clears existing mappings and then maps stack and heap vmo.
pub(super) fn clear_and_map(&self) {
self.root_vmar.clear().unwrap();
self.heap.alloc_and_map_vmo(&self.root_vmar).unwrap();
self.heap.alloc_and_map_vm(&self.root_vmar).unwrap();
}
}