diff --git a/os/src/main.rs b/os/src/main.rs
index 02e62a08..3d06bb1b 100644
--- a/os/src/main.rs
+++ b/os/src/main.rs
@@ -1,7 +1,5 @@
 #![no_std]
 #![no_main]
-#![feature(global_asm)]
-#![feature(asm)]
 #![feature(panic_info_message)]
 #![feature(alloc_error_handler)]
 
@@ -23,6 +21,8 @@ mod timer;
 mod sync;
 mod mm;
 
+use core::arch::global_asm;
+
 global_asm!(include_str!("entry.asm"));
 global_asm!(include_str!("link_app.S"));
 
@@ -52,4 +52,4 @@ pub fn rust_main() -> ! {
     timer::set_next_trigger();
     task::run_first_task();
     panic!("Unreachable in rust_main!");
-}
\ No newline at end of file
+}
diff --git a/os/src/mm/memory_set.rs b/os/src/mm/memory_set.rs
index ad3986a2..68d4221a 100644
--- a/os/src/mm/memory_set.rs
+++ b/os/src/mm/memory_set.rs
@@ -15,6 +15,7 @@ use crate::config::{
     TRAP_CONTEXT,
     USER_STACK_SIZE
 };
+use core::arch::asm;
 
 extern "C" {
     fn stext();
@@ -307,4 +308,4 @@ pub fn remap_test() {
         false,
     );
     println!("remap_test passed!");
-}
\ No newline at end of file
+}
diff --git a/os/src/sbi.rs b/os/src/sbi.rs
index 276c199d..c8ecbf1d 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/task/switch.rs b/os/src/task/switch.rs
index fa75be1a..dd3a2d3e 100644
--- a/os/src/task/switch.rs
+++ b/os/src/task/switch.rs
@@ -1,6 +1,7 @@
-global_asm!(include_str!("switch.S"));
-
 use super::TaskContext;
+use core::arch::global_asm;
+
+global_asm!(include_str!("switch.S"));
 
 extern "C" {
     pub fn __switch(
diff --git a/os/src/trap/mod.rs b/os/src/trap/mod.rs
index e6baba52..9bf0b1ef 100644
--- a/os/src/trap/mod.rs
+++ b/os/src/trap/mod.rs
@@ -21,6 +21,7 @@ use crate::task::{
 };
 use crate::timer::set_next_trigger;
 use crate::config::{TRAP_CONTEXT, TRAMPOLINE};
+use core::arch::{global_asm, asm};
 
 global_asm!(include_str!("trap.S"));
 
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/lib.rs b/user/src/lib.rs
index 1fae0fd2..5da90d74 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)]
 
diff --git a/user/src/syscall.rs b/user/src/syscall.rs
index ed3d16aa..b0095697 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;
 const SYSCALL_YIELD: usize = 124;
@@ -31,4 +33,4 @@ pub fn sys_yield() -> isize {
 
 pub fn sys_get_time() -> isize {
     syscall(SYSCALL_GET_TIME, [0, 0, 0])
-}
\ No newline at end of file
+}