diff --git a/os/src/lang_items.rs b/os/src/lang_items.rs
index eedbd83d..daf86320 100644
--- a/os/src/lang_items.rs
+++ b/os/src/lang_items.rs
@@ -1,4 +1,5 @@
 use core::panic::PanicInfo;
+use core::arch::asm;
 use crate::sbi::shutdown;
 use crate::task::current_kstack_top;
 
diff --git a/os/src/main.rs b/os/src/main.rs
index d4b0934e..3a960a65 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)]
 
@@ -24,6 +22,8 @@ mod mm;
 mod fs;
 mod drivers;
 
+use core::arch::global_asm;
+
 global_asm!(include_str!("entry.asm"));
 
 fn clear_bss() {
diff --git a/os/src/mm/memory_set.rs b/os/src/mm/memory_set.rs
index 575f5a34..30bc7689 100644
--- a/os/src/mm/memory_set.rs
+++ b/os/src/mm/memory_set.rs
@@ -14,6 +14,7 @@ use crate::config::{
     TRAMPOLINE,
     MMIO,
 };
+use core::arch::asm;
 
 extern "C" {
     fn stext();
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 5fd95f5b..f0f60afe 100644
--- a/os/src/trap/mod.rs
+++ b/os/src/trap/mod.rs
@@ -22,6 +22,7 @@ use crate::task::{
 };
 use crate::timer::{set_next_trigger, check_timer};
 use crate::config::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 4fe0e2a2..50b6439e 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)]
 #![feature(alloc_error_handler)]
diff --git a/user/src/syscall.rs b/user/src/syscall.rs
index 8d5b6f5b..e85fbbb9 100644
--- a/user/src/syscall.rs
+++ b/user/src/syscall.rs
@@ -1,3 +1,5 @@
+use core::arch::asm;
+
 const SYSCALL_DUP: usize = 24;
 const SYSCALL_OPEN: usize = 56;
 const SYSCALL_CLOSE: usize = 57;