Remove meaningless sstatus::set_sie() when initializing.

os/src/trap/context.rs

@@ -22,8 +22,6 @@ impl TrapContext {
         let mut sstatus = sstatus::read();
         // set CPU privilege to User after trapping back
         sstatus.set_spp(SPP::User);
-        // enable Supervisor mode interrupt after trapping back
-        sstatus.set_spie(true);
         let mut cx = Self {
             x: [0; 32],
             sstatus,

os/src/trap/mod.rs

@@ -10,7 +10,6 @@ use riscv::register::{
         Interrupt,
     },
     stval,
-    sstatus,
     sie,
 };
 use crate::syscall::syscall;
@@ -41,11 +40,6 @@ fn set_user_trap_entry() {
     }
 }
 
-#[allow(unused)]
-pub fn enable_interrupt() {
-    unsafe { sstatus::set_sie(); }
-}
-
 pub fn enable_timer_interrupt() {
     unsafe { sie::set_stimer(); }
 }