feat: add pmm, add vmm, add allocator, create memory management foundation

kernel/src/mem/address.rs

@@ -0,0 +1,36 @@
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+#[repr(transparent)]
+pub struct PhysAddr(pub u64);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+#[repr(transparent)]
+pub struct VirtAddr(pub u64);
+
+impl PhysAddr {
+    /// Convert physical address to virtual via HHDM offset
+    pub fn to_virt(self, hhdm_offset: u64) -> VirtAddr {
+        VirtAddr(self.0 + hhdm_offset)
+    }
+    
+    #[allow(dead_code)]
+    pub fn is_aligned(self) -> bool { self.0 % 4096 == 0 }
+    
+    #[allow(dead_code)]
+    pub fn align_down(self) -> Self { Self(self.0 & !0xFFF) }
+    
+    #[allow(dead_code)]
+    pub fn align_up(self) -> Self { Self((self.0 + 4095) & !0xFFF) }
+}
+
+impl VirtAddr {
+    #[allow(dead_code)]
+    pub fn to_phys(self, hhdm_offset: u64) -> Option<PhysAddr> {
+        if self.0 < hhdm_offset { return None; }
+        Some(PhysAddr(self.0 - hhdm_offset))
+    }
+
+    #[allow(dead_code)]
+    pub fn as_ptr<T>(self) -> *const T { self.0 as *const T }
+
+    pub fn as_mut_ptr<T>(self) -> *mut T { self.0 as *mut T }
+}