Implements malloc with size within page size (#971)

src/obkrnl/src/main.rs

@@ -18,6 +18,7 @@ mod imgfmt;
 mod malloc;
 mod panic;
 mod proc;
+mod uma;
 
 extern crate alloc;
 

src/obkrnl/src/malloc/stage2.rs

@@ -1,22 +1,55 @@
+use crate::config::PAGE_SIZE;
 use crate::context::Context;
+use crate::uma::UmaZone;
+use alloc::string::ToString;
+use alloc::sync::Arc;
+use alloc::vec::Vec;
 use core::alloc::Layout;
 
 /// Stage 2 kernel heap.
 ///
 /// This stage allocate a memory from a virtual memory management system. This struct is a merge of
 /// `malloc_type` and `malloc_type_internal` structure.
-pub struct Stage2 {}
+pub struct Stage2 {
+    zones: Vec<Arc<UmaZone>>, // kmemsize + kmemzones
+}
 
 impl Stage2 {
+    const KMEM_ZSHIFT: usize = 4;
+    const KMEM_ZBASE: usize = 16;
+    const KMEM_ZMASK: usize = Self::KMEM_ZBASE - 1;
+    const KMEM_ZSIZE: usize = PAGE_SIZE >> Self::KMEM_ZSHIFT;
+
+    /// See `kmeminit` on the PS4 for a reference.
     pub fn new() -> Self {
-        Self {}
+        let mut zones = Vec::with_capacity(Self::KMEM_ZSIZE + 1);
+        let mut last = 0;
+
+        for i in Self::KMEM_ZSHIFT.. {
+            // Stop if size larger than page size.
+            let size = 1usize << i;
+
+            if size > PAGE_SIZE {
+                break;
+            }
+
+            // Create zone.
+            let zone = Arc::new(UmaZone::new(size.to_string().into(), size));
+
+            while last <= size {
+                zones.push(zone.clone());
+                last += Self::KMEM_ZBASE;
+            }
+        }
+
+        Self { zones }
     }
 
     /// See `malloc` on the PS4 for a reference.
     ///
     /// # Safety
     /// `layout` must be nonzero.
-    pub unsafe fn alloc(&self, _: Layout) -> *mut u8 {
+    pub unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
         // Our implementation imply M_WAITOK.
         let td = Context::thread();
 
@@ -24,8 +57,22 @@ impl Stage2 {
             panic!("heap allocation in an interrupt handler is not supported");
         }
 
+        // TODO: Handle alignment.
+        let mut size = layout.size();
+
+        if size <= PAGE_SIZE {
+            // Round size.
+            if (size & Self::KMEM_ZMASK) != 0 {
+                // TODO: Refactor this for readability.
+                size = (size + Self::KMEM_ZBASE) & !Self::KMEM_ZMASK;
+            }
+
+            // TODO: There are more logic after this on the PS4.
+            self.zones[size >> Self::KMEM_ZSHIFT].alloc()
+        } else {
             todo!()
         }
+    }
 
     /// # Safety
     /// `ptr` must be obtained with [`Self::alloc()`] and `layout` must be the same one that was

src/obkrnl/src/uma/mod.rs

@@ -0,0 +1,16 @@
+use alloc::borrow::Cow;
+
+/// Implementation of `uma_zone` structure.
+pub struct UmaZone {}
+
+impl UmaZone {
+    /// See `uma_zcreate` on the PS4 for a reference.
+    pub fn new(_: Cow<'static, str>, _: usize) -> Self {
+        Self {}
+    }
+
+    /// See `uma_zalloc_arg` on the PS4 for a reference.
+    pub fn alloc(&self) -> *mut u8 {
+        todo!()
+    }
+}