diff --git a/os/src/batch.rs b/os/src/batch.rs
index 816e8b78..7f29b21b 100644
--- a/os/src/batch.rs
+++ b/os/src/batch.rs
@@ -1,6 +1,7 @@
 use lazy_static::*;
 use crate::trap::TrapContext;
 use crate::sync::UPSafeCell;
+use core::arch::asm;
 
 const USER_STACK_SIZE: usize = 4096 * 2;
 const KERNEL_STACK_SIZE: usize = 4096 * 2;
diff --git a/os/src/main.rs b/os/src/main.rs
index a01c22f0..3cea360f 100644
--- a/os/src/main.rs
+++ b/os/src/main.rs
@@ -1,9 +1,9 @@
 #![no_std]
 #![no_main]
-#![feature(global_asm)]
-#![feature(asm)]
 #![feature(panic_info_message)]
 
+use core::arch::global_asm;
+
 #[macro_use]
 mod console;
 mod lang_items;
diff --git a/os/src/sbi.rs b/os/src/sbi.rs
index 935fe24e..aa12b7f3 100644
--- a/os/src/sbi.rs
+++ b/os/src/sbi.rs
@@ -1,5 +1,7 @@
 #![allow(unused)]
 
+use core::arch::asm;
+
 const SBI_SET_TIMER: usize = 0;
 const SBI_CONSOLE_PUTCHAR: usize = 1;
 const SBI_CONSOLE_GETCHAR: usize = 2;
diff --git a/os/src/trap/mod.rs b/os/src/trap/mod.rs
index e42b05fb..98ae35cf 100644
--- a/os/src/trap/mod.rs
+++ b/os/src/trap/mod.rs
@@ -12,6 +12,7 @@ use riscv::register::{
 };
 use crate::syscall::syscall;
 use crate::batch::run_next_app;
+use core::arch::global_asm;
 
 global_asm!(include_str!("trap.S"));
 
@@ -47,4 +48,4 @@ pub fn trap_handler(cx: &mut TrapContext) -> &mut TrapContext {
     cx
 }
 
-pub use context::TrapContext;
\ No newline at end of file
+pub use context::TrapContext;
diff --git a/rust-toolchain b/rust-toolchain
index c9f86822..a8a61591 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-nightly-2021-12-15
+nightly-2022-01-01
diff --git a/user/src/bin/00hello_world.rs b/user/src/bin/00hello_world.rs
index 242749ac..f4f0332e 100644
--- a/user/src/bin/00hello_world.rs
+++ b/user/src/bin/00hello_world.rs
@@ -1,10 +1,11 @@
 #![no_std]
 #![no_main]
-#![feature(asm)]
 
 #[macro_use]
 extern crate user_lib;
 
+use core::arch::asm;
+
 #[no_mangle]
 fn main() -> i32 {
     println!("Hello, world!");
@@ -12,4 +13,4 @@ fn main() -> i32 {
         asm!("sret");
     }
     0
-}
\ No newline at end of file
+}
diff --git a/user/src/lib.rs b/user/src/lib.rs
index c06f9245..baa59e81 100644
--- a/user/src/lib.rs
+++ b/user/src/lib.rs
@@ -1,5 +1,4 @@
 #![no_std]
-#![feature(asm)]
 #![feature(linkage)]
 #![feature(panic_info_message)]
 
@@ -35,4 +34,4 @@ fn clear_bss() {
 use syscall::*;
 
 pub fn write(fd: usize, buf: &[u8]) -> isize { sys_write(fd, buf) }
-pub fn exit(exit_code: i32) -> isize { sys_exit(exit_code) }
\ No newline at end of file
+pub fn exit(exit_code: i32) -> isize { sys_exit(exit_code) }
diff --git a/user/src/syscall.rs b/user/src/syscall.rs
index bb7582f2..3889d305 100644
--- a/user/src/syscall.rs
+++ b/user/src/syscall.rs
@@ -1,3 +1,5 @@
+use core::arch::asm;
+
 const SYSCALL_WRITE: usize = 64;
 const SYSCALL_EXIT: usize = 93;