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https://github.com/panpaul/tiny_os
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2aa88154b4
Author | SHA1 | Date | |
---|---|---|---|
2aa88154b4 | |||
bca4e37ef2 |
@ -3,6 +3,7 @@
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#![no_main]
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// Features
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#![feature(asm_const)]
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#![feature(const_mut_refs)]
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#![feature(extern_types)]
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#![feature(naked_functions)]
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#![feature(panic_info_message)]
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|
286
kernel/src/vspace/allocator/bitmap.rs
Normal file
286
kernel/src/vspace/allocator/bitmap.rs
Normal file
@ -0,0 +1,286 @@
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use crate::arch::layout::PAGE_SIZE;
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use crate::vspace::addr::{AddressOps, PhysAddr};
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use core::alloc::{GlobalAlloc, Layout};
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use core::ptr::null_mut;
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use log::warn;
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use spin::Mutex;
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trait BitmapCfg: Copy + Clone {
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const CAPACITY: usize;
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const DEFAULT: Self;
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fn alloc_bits(&mut self) -> Option<usize>;
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fn dealloc_bits(&mut self, index: usize);
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}
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#[derive(Copy, Clone)]
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struct Bitmap32(u32);
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impl BitmapCfg for Bitmap32 {
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const CAPACITY: usize = u32::BITS as usize;
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const DEFAULT: Self = Self(0);
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fn alloc_bits(&mut self) -> Option<usize> {
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// fast-path
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let i = self.0.leading_zeros() as usize;
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if i > 0 {
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self.0 |= 1u32 << (Self::CAPACITY - i);
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return Some(Self::CAPACITY - i);
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}
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// check full
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if self.0 == u32::MAX {
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return None;
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}
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// slow-path
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for i in 0..Self::CAPACITY {
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if self.0 & (1 << i) == 0 {
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self.0 |= 1 << i;
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return Some(i);
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}
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}
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None
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}
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fn dealloc_bits(&mut self, index: usize) {
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if index < Self::CAPACITY {
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self.0 &= !(1 << index);
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}
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}
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}
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const BITS_PER_LEVEL: usize = 32;
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#[derive(Copy, Clone)]
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struct Bitmap<B: BitmapCfg> {
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bits: u32, // must not overflow with BITS_PER_LEVEL
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next: [B; BITS_PER_LEVEL],
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}
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const_assert!(core::mem::size_of::<u32>() * 8 >= BITS_PER_LEVEL);
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impl<B: BitmapCfg> BitmapCfg for Bitmap<B> {
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const CAPACITY: usize = BITS_PER_LEVEL * B::CAPACITY;
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const DEFAULT: Self = Self {
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bits: 0,
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next: [B::DEFAULT; BITS_PER_LEVEL],
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};
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fn alloc_bits(&mut self) -> Option<usize> {
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if self.bits == u32::MAX {
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return None;
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}
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// fast-path
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loop {
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let i = self.bits.leading_zeros() as usize;
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if i == 0 {
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break;
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}
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if let Some(index) = self.alloc_index(BITS_PER_LEVEL - i) {
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return Some(index);
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}
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}
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// slow-path
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for i in 0..BITS_PER_LEVEL {
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if self.bits & (1 << i) == 0 {
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if let Some(index) = self.alloc_index(i) {
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return Some(index);
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}
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}
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}
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None
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}
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fn dealloc_bits(&mut self, index: usize) {
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let i = index / B::CAPACITY;
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if i < BITS_PER_LEVEL {
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self.next[i].dealloc_bits(index % B::CAPACITY);
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self.bits &= !(1 << i);
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}
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}
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}
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impl<B: BitmapCfg> Bitmap<B> {
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fn alloc_index(&mut self, i: usize) -> Option<usize> {
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if let Some(sub) = self.next[i].alloc_bits() {
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return Some(i * B::CAPACITY + sub);
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}
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self.bits |= 1 << i;
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None
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}
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}
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// 1k pages, consumes (32+1)*32/8 = 132 bytes, allocates 1k * 4KiB = 4MiB memory
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type Bitmap1K = Bitmap<Bitmap32>;
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// 32k pages, consumes (32*(32+1)+1)*32/8 = 4228 bytes, allocates 32k * 4KiB = 128MiB memory
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type Bitmap32K = Bitmap<Bitmap1K>;
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const_assert_eq!(core::mem::size_of::<Bitmap1K>(), (32 + 1) * 32 / 8);
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const_assert_eq!(
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core::mem::size_of::<Bitmap32K>(),
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(32 * (32 + 1) + 1) * 32 / 8
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);
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struct BitmapAllocator<B: BitmapCfg = Bitmap32K> {
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bitmap: Mutex<B>,
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base: PhysAddr,
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}
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unsafe impl<B: BitmapCfg> GlobalAlloc for BitmapAllocator<B> {
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unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
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if layout.size() > PAGE_SIZE || layout.align() > PAGE_SIZE {
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warn!("unsupported layout: {:?}, page size: {}", layout, PAGE_SIZE);
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return null_mut();
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}
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let bit = self.bitmap.lock().alloc_bits();
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if let Some(index) = bit {
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let addr = self.base + index * PAGE_SIZE;
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return addr.as_mut_ptr();
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}
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null_mut()
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}
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unsafe fn dealloc(&self, ptr: *mut u8, _: Layout) {
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let bit = (PhysAddr::from(ptr) - self.base).as_usize() / PAGE_SIZE;
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self.bitmap.lock().dealloc_bits(bit);
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}
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}
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impl<B: BitmapCfg> BitmapAllocator<B> {
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pub fn new(base: PhysAddr) -> Self {
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Self {
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bitmap: Mutex::new(B::DEFAULT),
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base,
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}
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}
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}
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pub type BitmapAllocator32K = BitmapAllocator<Bitmap32K>;
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test_case]
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fn test_bitmap32() {
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let mut bitmap = Bitmap32::DEFAULT;
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// alloc from empty
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for i in 0..32 {
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assert_eq!(bitmap.alloc_bits(), Some(i));
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}
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assert_eq!(bitmap.alloc_bits(), None);
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// dealloc
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for i in 0..16 {
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bitmap.dealloc_bits(i * 2);
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}
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// predictable alloc from dealloc pattern
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for i in 0..16 {
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assert_eq!(bitmap.alloc_bits(), Some(i * 2));
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}
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// invalid dealloc
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assert_eq!(bitmap.alloc_bits(), None);
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bitmap.dealloc_bits(32);
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assert_eq!(bitmap.alloc_bits(), None);
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}
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#[test_case]
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fn test_bitmap1k() {
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let mut bitmap = Bitmap1K::DEFAULT;
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// alloc from empty
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for i in 0..(32 * BITS_PER_LEVEL) {
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assert_eq!(bitmap.alloc_bits(), Some(i));
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}
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// free the second slot
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for i in 0..32 {
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bitmap.dealloc_bits(32 + i);
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}
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// alloc again
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for i in 0..32 {
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assert_eq!(bitmap.alloc_bits(), Some(32 + i));
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}
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// invalid dealloc
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assert_eq!(bitmap.alloc_bits(), None);
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bitmap.dealloc_bits(32 * BITS_PER_LEVEL);
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assert_eq!(bitmap.alloc_bits(), None);
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}
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#[test_case]
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fn test_bitmap32k() {
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let mut bitmap = Bitmap32K::DEFAULT;
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// alloc from empty
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for i in 0..(32 * BITS_PER_LEVEL * BITS_PER_LEVEL) {
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assert_eq!(bitmap.alloc_bits(), Some(i));
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}
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// free the second slot
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for i in 0..32 {
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bitmap.dealloc_bits(32 + i);
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}
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// free the third layer
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for i in 0..(32 * BITS_PER_LEVEL) {
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bitmap.dealloc_bits(32 * BITS_PER_LEVEL * 2 + i);
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}
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// alloc again (second slot)
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for i in 0..32 {
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assert_eq!(bitmap.alloc_bits(), Some(32 + i));
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}
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// alloc again (third layer)
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for i in 0..(32 * BITS_PER_LEVEL) {
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assert_eq!(bitmap.alloc_bits(), Some(32 * BITS_PER_LEVEL * 2 + i));
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}
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// invalid dealloc
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assert_eq!(bitmap.alloc_bits(), None);
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bitmap.dealloc_bits(32 * BITS_PER_LEVEL * BITS_PER_LEVEL);
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assert_eq!(bitmap.alloc_bits(), None);
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}
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#[test_case]
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fn test_bitmap_allocator() {
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let allocator = BitmapAllocator32K::new(PhysAddr(0x42));
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// alloc from empty
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for i in 0..32 {
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let ptr =
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unsafe { allocator.alloc(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) };
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assert_eq!(PhysAddr::from(ptr).as_usize(), 0x42 + i * PAGE_SIZE);
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}
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// dealloc
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for i in 0..16 {
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unsafe {
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allocator.dealloc(
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PhysAddr(0x42 + i * 2 * PAGE_SIZE).as_mut_ptr(),
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Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap(),
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);
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}
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}
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// predictable alloc from dealloc pattern
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for i in 0..16 {
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let ptr =
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unsafe { allocator.alloc(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) };
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assert_eq!(PhysAddr::from(ptr).as_usize(), 0x42 + i * 2 * PAGE_SIZE);
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}
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}
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}
|
223
kernel/src/vspace/allocator/freelist.rs
Normal file
223
kernel/src/vspace/allocator/freelist.rs
Normal file
@ -0,0 +1,223 @@
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// adapted from https://os.phil-opp.com/allocator-designs/#linked-list-allocator
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use crate::utils::then::Then;
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use crate::vspace::addr::{AddressOps, PhysAddr};
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use core::alloc::{GlobalAlloc, Layout};
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use spin::Mutex;
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struct ListNode {
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size: usize,
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next: Option<&'static mut ListNode>,
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}
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impl ListNode {
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const fn new(size: usize) -> Self {
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Self { size, next: None }
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}
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fn start_addr(&self) -> PhysAddr {
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PhysAddr(self as *const _ as usize)
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}
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fn end_addr(&self) -> PhysAddr {
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self.start_addr() + self.size
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}
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fn fit(&self, size: usize, align: usize) -> Result<PhysAddr, ()> {
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let alloc_start = self.start_addr().align_up(align);
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let alloc_end = alloc_start + size;
|
||||
|
||||
if alloc_end > self.end_addr() {
|
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return Err(());
|
||||
}
|
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|
||||
let excess_size = (self.end_addr() - alloc_end).as_usize();
|
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if excess_size > 0 && excess_size < core::mem::size_of::<ListNode>() {
|
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// GlobalAlloc requires that dealloc be called with the original size and alignment,
|
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// so we can't "waste" the remaining space and must return an error.
|
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return Err(());
|
||||
}
|
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|
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Ok(alloc_start)
|
||||
}
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}
|
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|
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struct FreeList {
|
||||
head: ListNode,
|
||||
}
|
||||
|
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impl FreeList {
|
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const fn new() -> Self {
|
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Self {
|
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head: ListNode::new(0),
|
||||
}
|
||||
}
|
||||
|
||||
fn alloc_node<F, V>(&mut self, mut predicate: F) -> Option<(&'static mut ListNode, V)>
|
||||
where F: FnMut(&mut ListNode) -> Result<V, ()> {
|
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let mut current = &mut self.head;
|
||||
while let Some(ref mut region) = current.next {
|
||||
if let Ok(v) = predicate(region) {
|
||||
let next = region.next.take();
|
||||
let ret = Some((current.next.take().unwrap(), v));
|
||||
current.next = next;
|
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return ret;
|
||||
} else {
|
||||
current = current.next.as_mut().unwrap();
|
||||
}
|
||||
}
|
||||
None
|
||||
}
|
||||
|
||||
fn align_layout(layout: Layout) -> (usize, usize) {
|
||||
let layout = layout
|
||||
.align_to(core::mem::align_of::<ListNode>())
|
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.expect("adjusting alignment failed")
|
||||
.pad_to_align();
|
||||
let size = layout.size().max(core::mem::size_of::<ListNode>());
|
||||
(size, layout.align())
|
||||
}
|
||||
|
||||
unsafe fn alloc(&mut self, layout: Layout) -> *mut u8 {
|
||||
let (size, align) = Self::align_layout(layout);
|
||||
|
||||
if let Some((region, alloc_start)) = self.alloc_node(|region| region.fit(size, align)) {
|
||||
let alloc_end = alloc_start + size;
|
||||
let excess_size = (region.end_addr() - alloc_end).as_usize();
|
||||
if excess_size > 0 {
|
||||
self.dealloc(alloc_end, excess_size);
|
||||
}
|
||||
alloc_start.as_mut_ptr()
|
||||
} else {
|
||||
core::ptr::null_mut()
|
||||
}
|
||||
}
|
||||
|
||||
unsafe fn dealloc(&mut self, start: PhysAddr, size: usize) {
|
||||
assert_eq!(start.align_up(core::mem::align_of::<ListNode>()), start);
|
||||
assert!(size >= core::mem::size_of::<ListNode>());
|
||||
|
||||
let mut node = ListNode::new(size);
|
||||
node.next = self.head.next.take();
|
||||
let node_ptr = start.as_mut_ptr::<ListNode>();
|
||||
node_ptr.write(node);
|
||||
self.head.next = Some(&mut *node_ptr);
|
||||
}
|
||||
|
||||
pub fn reserve(&mut self, start: PhysAddr, size: usize) {
|
||||
if let Some((region, _)) = self
|
||||
.alloc_node(|region| (region.start_addr() <= start).chain(|| region.fit(size, 1), ()))
|
||||
{
|
||||
/* layout
|
||||
* region: | before | [start +: size] | after |
|
||||
* ^ ^ ^ ^ region.end_addr()
|
||||
* | | alloc_start |
|
||||
* | | alloc_end
|
||||
* | region.start_addr()
|
||||
*/
|
||||
|
||||
let region_start = region.start_addr();
|
||||
let region_end = region.end_addr();
|
||||
|
||||
let before_size = (start - region_start).as_usize();
|
||||
if before_size > 0 {
|
||||
unsafe { self.dealloc(region_start, before_size) }
|
||||
}
|
||||
|
||||
let after_size = (region_end - (start + size)).as_usize();
|
||||
if after_size > 0 {
|
||||
unsafe { self.dealloc(start + size, after_size) }
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
pub struct FreeListAllocator {
|
||||
list: Mutex<FreeList>,
|
||||
}
|
||||
|
||||
impl FreeListAllocator {
|
||||
pub fn new(start: PhysAddr, size: usize) -> Self {
|
||||
let mut list = FreeList::new();
|
||||
unsafe { list.dealloc(start, size) }
|
||||
Self {
|
||||
list: Mutex::new(list),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
unsafe impl GlobalAlloc for FreeListAllocator {
|
||||
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
|
||||
self.list.lock().alloc(layout)
|
||||
}
|
||||
|
||||
unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
|
||||
let (size, _) = FreeList::align_layout(layout);
|
||||
self.list.lock().dealloc(PhysAddr::from(ptr), size)
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
use crate::arch::layout::PAGE_SIZE;
|
||||
|
||||
#[test_case]
|
||||
fn test_freelist() {
|
||||
const BASE: PhysAddr = PhysAddr(0x80300000);
|
||||
|
||||
let allocator = FreeListAllocator::new(BASE, 32 * PAGE_SIZE);
|
||||
for i in 0..32 {
|
||||
let ptr =
|
||||
unsafe { allocator.alloc(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) };
|
||||
assert_eq!(ptr as usize, (BASE + i * PAGE_SIZE).as_usize());
|
||||
}
|
||||
|
||||
let ptr =
|
||||
unsafe { allocator.alloc(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) };
|
||||
assert_eq!(ptr, core::ptr::null_mut());
|
||||
|
||||
for i in (0..32).rev() {
|
||||
let ptr = (BASE + i * PAGE_SIZE).as_mut_ptr();
|
||||
unsafe {
|
||||
allocator.dealloc(ptr, Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap())
|
||||
};
|
||||
}
|
||||
|
||||
let ptr =
|
||||
unsafe { allocator.alloc(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) };
|
||||
assert_eq!(ptr as usize, BASE.as_usize());
|
||||
}
|
||||
|
||||
#[test_case]
|
||||
fn test_freelist_reserve() {
|
||||
const BASE: PhysAddr = PhysAddr(0x80300000);
|
||||
|
||||
let allocator = FreeListAllocator::new(BASE, 32 * PAGE_SIZE);
|
||||
allocator
|
||||
.list
|
||||
.lock()
|
||||
.reserve(BASE + 4 * PAGE_SIZE, 4 * PAGE_SIZE);
|
||||
|
||||
let mut cnt = 32 - 4;
|
||||
loop {
|
||||
let ptr =
|
||||
unsafe { allocator.alloc(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) };
|
||||
if ptr.is_null() {
|
||||
assert_eq!(cnt, 0);
|
||||
break;
|
||||
}
|
||||
|
||||
let ptr = PhysAddr::from(ptr);
|
||||
assert!(
|
||||
!(BASE + 4 * PAGE_SIZE <= ptr && ptr < BASE + (4 + 4) * PAGE_SIZE),
|
||||
"Bad alloc: returned ptr: {:?}, reserved range: {:?}->{:?}",
|
||||
ptr,
|
||||
BASE + 4 * PAGE_SIZE,
|
||||
BASE + (4 + 4) * PAGE_SIZE
|
||||
);
|
||||
|
||||
cnt -= 1;
|
||||
}
|
||||
}
|
||||
}
|
5
kernel/src/vspace/allocator/mod.rs
Normal file
5
kernel/src/vspace/allocator/mod.rs
Normal file
@ -0,0 +1,5 @@
|
||||
mod bitmap;
|
||||
mod freelist;
|
||||
|
||||
pub use bitmap::*;
|
||||
pub use freelist::*;
|
@ -1,2 +1,3 @@
|
||||
pub mod addr;
|
||||
pub mod allocator;
|
||||
pub mod paging;
|
||||
|
Loading…
Reference in New Issue
Block a user