diff --git a/ostd/src/arch/loongarch/task/mod.rs b/ostd/src/arch/loongarch/task/mod.rs
index 5b5e2bf86..0e07f746f 100644
--- a/ostd/src/arch/loongarch/task/mod.rs
+++ b/ostd/src/arch/loongarch/task/mod.rs
@@ -6,44 +6,43 @@ use crate::task::TaskContextApi;
 
 core::arch::global_asm!(include_str!("switch.S"));
 
-#[derive(Debug, Default, Clone, Copy)]
+#[derive(Debug, Clone)]
 #[repr(C)]
 pub(crate) struct TaskContext {
-    pub regs: CalleeRegs,
-    pub ra: usize,
+    regs: CalleeRegs,
+    ra: usize,
+}
+
+impl TaskContext {
+    /// Creates a new `TaskContext`.
+    pub(crate) const fn new() -> Self {
+        TaskContext {
+            regs: CalleeRegs::new(),
+            ra: 0,
+        }
+    }
 }
 
 /// Callee-saved registers.
-#[derive(Debug, Default, Clone, Copy)]
+#[derive(Debug, Clone)]
 #[repr(C)]
-pub struct CalleeRegs {
-    /// sp
-    pub sp: usize,
-    /// fp
-    pub fp: usize,
-    /// s0
-    pub s0: usize,
-    /// s1
-    pub s1: usize,
-    /// s2
-    pub s2: usize,
-    /// s3
-    pub s3: usize,
-    /// s4
-    pub s4: usize,
-    /// s5
-    pub s5: usize,
-    /// s6
-    pub s6: usize,
-    /// s7
-    pub s7: usize,
-    /// s8
-    pub s8: usize,
+struct CalleeRegs {
+    sp: usize,
+    fp: usize,
+    s0: usize,
+    s1: usize,
+    s2: usize,
+    s3: usize,
+    s4: usize,
+    s5: usize,
+    s6: usize,
+    s7: usize,
+    s8: usize,
 }
 
 impl CalleeRegs {
-    /// Creates new `CalleeRegs`
-    pub const fn new() -> Self {
+    /// Creates a new `CalleeRegs`.
+    pub(self) const fn new() -> Self {
         CalleeRegs {
             sp: 0,
             fp: 0,
@@ -60,15 +59,6 @@ impl CalleeRegs {
     }
 }
 
-impl TaskContext {
-    pub const fn new() -> Self {
-        TaskContext {
-            regs: CalleeRegs::new(),
-            ra: 0,
-        }
-    }
-}
-
 impl TaskContextApi for TaskContext {
     fn set_instruction_pointer(&mut self, ip: usize) {
         self.ra = ip;
diff --git a/ostd/src/arch/riscv/task/mod.rs b/ostd/src/arch/riscv/task/mod.rs
index 55eb30f52..f488f0899 100644
--- a/ostd/src/arch/riscv/task/mod.rs
+++ b/ostd/src/arch/riscv/task/mod.rs
@@ -6,48 +6,45 @@ use crate::task::TaskContextApi;
 
 core::arch::global_asm!(include_str!("switch.S"));
 
-#[derive(Debug, Default, Clone, Copy)]
+#[derive(Debug, Clone)]
 #[repr(C)]
 pub(crate) struct TaskContext {
-    pub regs: CalleeRegs,
-    pub pc: usize,
+    regs: CalleeRegs,
+    ra: usize,
+}
+
+impl TaskContext {
+    /// Creates a new `TaskContext`.
+    pub(crate) const fn new() -> Self {
+        TaskContext {
+            regs: CalleeRegs::new(),
+            ra: 0,
+        }
+    }
 }
 
 /// Callee-saved registers.
-#[derive(Debug, Default, Clone, Copy)]
+#[derive(Debug, Clone)]
 #[repr(C)]
-pub struct CalleeRegs {
-    /// sp
-    pub sp: u64,
-    /// s0
-    pub s0: u64,
-    /// s1
-    pub s1: u64,
-    /// s2
-    pub s2: u64,
-    /// s3
-    pub s3: u64,
-    /// s4
-    pub s4: u64,
-    /// s5
-    pub s5: u64,
-    /// s6
-    pub s6: u64,
-    /// s7
-    pub s7: u64,
-    /// s8
-    pub s8: u64,
-    /// s9
-    pub s9: u64,
-    /// s10
-    pub s10: u64,
-    /// s11
-    pub s11: u64,
+struct CalleeRegs {
+    sp: u64,
+    s0: u64,
+    s1: u64,
+    s2: u64,
+    s3: u64,
+    s4: u64,
+    s5: u64,
+    s6: u64,
+    s7: u64,
+    s8: u64,
+    s9: u64,
+    s10: u64,
+    s11: u64,
 }
 
 impl CalleeRegs {
-    /// Creates new `CalleeRegs`
-    pub const fn new() -> Self {
+    /// Creates a new `CalleeRegs`.
+    pub(self) const fn new() -> Self {
         CalleeRegs {
             sp: 0,
             s0: 0,
@@ -66,18 +63,9 @@ impl CalleeRegs {
     }
 }
 
-impl TaskContext {
-    pub const fn new() -> Self {
-        TaskContext {
-            regs: CalleeRegs::new(),
-            pc: 0,
-        }
-    }
-}
-
 impl TaskContextApi for TaskContext {
     fn set_instruction_pointer(&mut self, ip: usize) {
-        self.pc = ip;
+        self.ra = ip;
     }
 
     fn set_stack_pointer(&mut self, sp: usize) {
diff --git a/ostd/src/arch/x86/task/mod.rs b/ostd/src/arch/x86/task/mod.rs
index 951263207..f609ba52e 100644
--- a/ostd/src/arch/x86/task/mod.rs
+++ b/ostd/src/arch/x86/task/mod.rs
@@ -6,16 +6,16 @@ use crate::task::TaskContextApi;
 
 core::arch::global_asm!(include_str!("switch.S"));
 
-#[derive(Debug, Default, Clone, Copy)]
+#[derive(Debug, Clone)]
 #[repr(C)]
 pub(crate) struct TaskContext {
-    pub regs: CalleeRegs,
-    pub rip: usize,
-    pub fsbase: usize,
+    regs: CalleeRegs,
+    rip: usize,
+    fsbase: usize,
 }
 
 impl TaskContext {
-    pub const fn new() -> Self {
+    pub(crate) const fn new() -> Self {
         Self {
             regs: CalleeRegs::new(),
             rip: 0,
@@ -25,28 +25,21 @@ impl TaskContext {
 }
 
 /// Callee-saved registers.
-#[derive(Debug, Default, Clone, Copy)]
+#[derive(Debug, Clone)]
 #[repr(C)]
-pub struct CalleeRegs {
-    /// RSP
-    pub rsp: u64,
-    /// RBX
-    pub rbx: u64,
-    /// RBP
-    pub rbp: u64,
-    /// R12
-    pub r12: u64,
-    /// R13
-    pub r13: u64,
-    /// R14
-    pub r14: u64,
-    /// R15
-    pub r15: u64,
+struct CalleeRegs {
+    rsp: u64,
+    rbx: u64,
+    rbp: u64,
+    r12: u64,
+    r13: u64,
+    r14: u64,
+    r15: u64,
 }
 
 impl CalleeRegs {
     /// Creates new `CalleeRegs`
-    pub const fn new() -> Self {
+    pub(self) const fn new() -> Self {
         CalleeRegs {
             rsp: 0,
             rbx: 0,
diff --git a/ostd/src/task/mod.rs b/ostd/src/task/mod.rs
index c129f6339..386534cb9 100644
--- a/ostd/src/task/mod.rs
+++ b/ostd/src/task/mod.rs
@@ -191,7 +191,7 @@ impl TaskOptions {
 
         let kstack = KernelStack::new_with_guard_page()?;
 
-        let mut ctx = TaskContext::default();
+        let mut ctx = TaskContext::new();
         ctx.set_instruction_pointer(kernel_task_entry as usize);
         // We should reserve space for the return address in the stack, otherwise
         // we will write across the page boundary due to the implementation of