feat: 释放slab中的空闲页面到buddy (#932)

* patch: 释放slab中的空闲页面到buddy

* 校验释放的slab_page的起始地址与大小 & SCAllcator增加空闲块计数器

kernel/src/mm/allocator/kernel_allocator.rs

@@ -51,7 +51,7 @@ impl KernelAllocator {
         return Ok(NonNull::from(slice));
     }
 
-    unsafe fn free_in_buddy(&self, ptr: *mut u8, layout: Layout) {
+    pub(super) unsafe fn free_in_buddy(&self, ptr: *mut u8, layout: Layout) {
         // 由于buddy分配的页数量是2的幂，因此释放的时候也需要按照2的幂向上取整。
         let count = (page_align_up(layout.size()) / MMArch::PAGE_SIZE).next_power_of_two();
         let page_frame_count = PageFrameCount::new(count);

kernel/src/mm/allocator/slab.rs

@@ -4,12 +4,16 @@ use alloc::boxed::Box;
 use log::debug;
 use slabmalloc::*;
 
+use crate::{arch::MMArch, mm::MemoryManagementArch, KERNEL_ALLOCATOR};
+
 // 全局slab分配器
 pub(crate) static mut SLABALLOCATOR: Option<SlabAllocator> = None;
 
 // slab初始化状态
 pub(crate) static mut SLABINITSTATE: AtomicBool = AtomicBool::new(false);
 
+static SLAB_CALLBACK: SlabCallback = SlabCallback;
+
 /// slab分配器，实际为一堆小的allocator，可以在里面装4K的page
 /// 利用这些allocator可以为对象分配不同大小的空间
 pub(crate) struct SlabAllocator {
@@ -52,7 +56,7 @@ impl SlabAllocator {
     ) -> Result<(), AllocationError> {
         if let Some(nptr) = NonNull::new(ptr) {
             self.zone
-                .deallocate(nptr, layout)
+                .deallocate(nptr, layout, &SLAB_CALLBACK)
                 .expect("Couldn't deallocate");
             return Ok(());
         } else {
@@ -80,3 +84,13 @@ pub unsafe fn slab_usage() -> SlabUsage {
         SlabUsage::new(0, 0)
     }
 }
+
+/// 归还slab_page给buddy的回调
+pub struct SlabCallback;
+impl CallBack for SlabCallback {
+    unsafe fn free_slab_page(&self, base_addr: *mut u8, size: usize) {
+        assert_eq!(base_addr as usize & (MMArch::PAGE_SIZE - 1), 0); // 确认地址4k对齐
+        assert_eq!(size, MMArch::PAGE_SIZE); // 确认释放的slab_page大小
+        KERNEL_ALLOCATOR.free_in_buddy(base_addr, Layout::from_size_align_unchecked(size, 1));
+    }
+}