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Harden the early allocator

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This commit is contained in:
Ruihan Li 2025-03-15 14:39:00 +08:00 committed by Junyang Zhang
parent 14685cce5d
commit 624dcf712a
1 changed files with 14 additions and 11 deletions
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25
ostd/src/mm/frame/allocator.rs
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@ -302,19 +302,22 @@ impl EarlyFrameAllocator {
/// Allocates a contiguous range of frames.
pub fn alloc(&mut self, layout: Layout) -> Option<Paddr> {
let size = layout.size().align_up(PAGE_SIZE);
let allocated = self.under_4g_end.align_up(layout.align());
if allocated + size <= self.under_4g_range.end {
// Allocated below 4G.
self.under_4g_end = allocated + size;
Some(allocated)
} else {
// Try above 4G.
let allocated = self.max_end.align_up(layout.align());
if allocated + size <= self.max_range.end {
self.max_end = allocated + size;
let align = layout.align().max(PAGE_SIZE);
for (tail, end) in [
(&mut self.under_4g_end, self.under_4g_range.end),
(&mut self.max_end, self.max_range.end),
] {
let allocated = tail.align_up(align);
if let Some(allocated_end) = allocated.checked_add(size)
&& allocated_end <= end
{
*tail = allocated_end;
return Some(allocated);
}
Some(allocated)
}
None
}
pub(super) fn allocated_regions(&self) -> (Range<Paddr>, Range<Paddr>) {