diff --git a/kernel/rustkernel/src/console/mod.rs b/kernel/rustkernel/src/console/mod.rs
index 49153de..8e79fa8 100644
--- a/kernel/rustkernel/src/console/mod.rs
+++ b/kernel/rustkernel/src/console/mod.rs
@@ -13,7 +13,7 @@ pub mod uart;
 
 use crate::{
     fs::file::{devsw, CONSOLE},
-    proc::proc::{killed, procdump, wakeup, Proc},
+    proc::proc::{procdump, wakeup, Proc},
     sync::mutex::Mutex,
 };
 use core::{ffi::c_void, ptr::addr_of_mut};
@@ -114,7 +114,7 @@ pub fn consoleread(user_dst: i32, mut dst: u64, mut n: i32) -> i32 {
             // Wait until interrupt handler has put
             // some input into cons.buffer.
             while console.read_index == console.write_index {
-                if killed(addr_of_mut!(*Proc::current().unwrap())) != 0 {
+                if Proc::current().unwrap().is_killed() {
                     // cons.lock.unlock();
                     return -1;
                 }
diff --git a/kernel/rustkernel/src/io/pipe.rs b/kernel/rustkernel/src/io/pipe.rs
index 0b48dc2..e8b0d0d 100644
--- a/kernel/rustkernel/src/io/pipe.rs
+++ b/kernel/rustkernel/src/io/pipe.rs
@@ -4,7 +4,7 @@ use crate::{
         kalloc::{kalloc, kfree},
         virtual_memory::{copyin, copyout},
     },
-    proc::proc::{killed, wakeup, Proc},
+    proc::proc::{wakeup, Proc},
     sync::spinlock::Spinlock,
 };
 use core::ptr::{addr_of, addr_of_mut};
@@ -92,7 +92,7 @@ impl Pipe {
         let guard = self.lock.lock();
 
         while i < num_bytes {
-            if self.is_read_open == 0 || killed(addr_of_mut!(*proc)) > 0 {
+            if self.is_read_open == 0 || proc.is_killed() {
                 return Err(PipeError::ProcessKilled);
             }
             if self.bytes_written == self.bytes_read + PIPESIZE as u32 {
@@ -121,7 +121,7 @@ impl Pipe {
 
         // DOC: pipe-empty
         while self.bytes_read == self.bytes_written && self.is_write_open > 0 {
-            if killed(addr_of_mut!(*proc)) > 0 {
+            if proc.is_killed() {
                 return Err(PipeError::ProcessKilled);
             } else {
                 // DOC: piperead-sleep
diff --git a/kernel/rustkernel/src/proc/proc.rs b/kernel/rustkernel/src/proc/proc.rs
index 9edecad..927ae19 100644
--- a/kernel/rustkernel/src/proc/proc.rs
+++ b/kernel/rustkernel/src/proc/proc.rs
@@ -125,6 +125,41 @@ impl Proc {
             unsafe { Some(&mut *p) }
         }
     }
+    /// Kill the process with the given pid.
+    /// Returns true if the process was killed.
+    /// The victim won't exit until it tries to return
+    /// to user space (see usertrap() in trap.c).
+    pub unsafe fn kill(pid: i32) -> bool {
+        for p in &mut proc {
+            let _guard = p.lock.lock();
+        
+            if p.pid == pid {
+                p.killed = 1;
+            
+                if p.state == ProcState::Sleeping {
+                    // Wake process from sleep().
+                    p.state = ProcState::Runnable;
+                }
+            
+                return true;
+            }
+        }
+
+        false
+    }
+
+    pub fn is_killed(&self) -> bool {
+        let _guard = self.lock.lock();
+        self.killed > 0
+    }
+    pub fn set_killed(&mut self, killed: bool) {
+        let _guard = self.lock.lock();
+        if killed {
+            self.killed = 1;
+        } else {
+            self.killed = 0;
+        }
+    }
 }
 
 /// Return the current struct proc *, or zero if none.
@@ -260,31 +295,23 @@ pub unsafe fn sleep(chan: *mut c_void) {
 /// to user space (see usertrap() in trap.c).
 #[no_mangle]
 pub unsafe extern "C" fn kill(pid: i32) -> i32 {
-    for p in &mut proc {
-        let _guard = p.lock.lock();
-
-        if p.pid == pid {
-            p.killed = 1;
-
-            if p.state == ProcState::Sleeping {
-                // Wake process from sleep().
-                p.state = ProcState::Runnable;
-            }
-
-            return 0;
-        }
+    if Proc::kill(pid) {
+        1
+    } else {
+        0
     }
-    -1
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn setkilled(p: *mut Proc) {
-    let _guard = (*p).lock.lock();
-    (*p).killed = 1;
+    (*p).set_killed(true);
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn killed(p: *mut Proc) -> i32 {
-    let _guard = (*p).lock.lock();
-    (*p).killed
+    if (*p).is_killed() {
+        1
+    } else {
+        0
+    }
 }
diff --git a/kernel/rustkernel/src/syscall.rs b/kernel/rustkernel/src/syscall.rs
index 1afa2a7..ecee9d4 100644
--- a/kernel/rustkernel/src/syscall.rs
+++ b/kernel/rustkernel/src/syscall.rs
@@ -85,7 +85,7 @@ impl Syscall {
             Syscall::Kill => {
                 let mut pid = 0i32;
                 argint(0, addr_of_mut!(pid));
-                proc::kill(pid) as u64
+                Proc::kill(pid) as u64
             }
             Syscall::Exec => sys_exec(),
             Syscall::Fstat => {
@@ -157,7 +157,7 @@ impl Syscall {
                 let mut ticks = CLOCK_TICKS.lock_spinning();
 
                 while *ticks < *ticks + n as usize {
-                    if proc::killed(addr_of!(*Proc::current().unwrap()).cast_mut()) > 0 {
+                    if Proc::current().unwrap().is_killed() {
                         return -1i64 as u64;
                     }
                     // Sleep until the value changes.
diff --git a/kernel/rustkernel/src/trap.rs b/kernel/rustkernel/src/trap.rs
index cb4aa53..8c9fd55 100644
--- a/kernel/rustkernel/src/trap.rs
+++ b/kernel/rustkernel/src/trap.rs
@@ -3,12 +3,12 @@ use crate::{
     println,
     proc::{
         cpu::Cpu,
-        proc::{exit, killed, r#yield, setkilled, wakeup, Proc, ProcState},
+        proc::{exit, r#yield, wakeup, Proc, ProcState},
     },
     sync::mutex::Mutex,
     syscall::syscall,
 };
-use core::ptr::{addr_of, addr_of_mut};
+use core::ptr::addr_of;
 
 extern "C" {
     pub fn kernelvec();
@@ -229,8 +229,8 @@ pub unsafe extern "C" fn usertrap() {
 
     if r_scause() == 8 {
         // System call
-
-        if killed(addr_of_mut!(*proc)) > 0 {
+        
+        if proc.is_killed() {
             exit(-1);
         }
 
@@ -254,10 +254,10 @@ pub unsafe extern "C" fn usertrap() {
             r_sepc(),
             r_stval()
         );
-        setkilled(addr_of_mut!(*proc));
+        proc.set_killed(true);
     }
 
-    if killed(addr_of_mut!(*proc)) > 0 {
+    if proc.is_killed() {
         exit(-1);
     }