Disable kernel traps before going to userspace

ostd/src/arch/loongarch/trap/trap.rs

@@ -77,6 +77,9 @@ impl RawUserContext {
     /// On return, the context will be reset to the status before the trap.
     /// Trap reason will be placed at `estat`.
     pub(in crate::arch) fn run(&mut self) {
+        // Return to userspace with interrupts disabled. Otherwise, interrupts
+        // after switching `SAVE_SCRATCH` will mess up the CPU state.
+        crate::arch::irq::disable_local();
         unsafe { run_user(self as *mut RawUserContext) }
     }
 }

ostd/src/arch/riscv/trap/trap.rs

@@ -103,6 +103,9 @@ impl RawUserContext {
     /// On return, the context will be reset to the status before the trap.
     /// Trap reason and error code will be placed at `scause` and `stval`.
     pub(in crate::arch) fn run(&mut self) {
+        // Return to userspace with interrupts disabled. Otherwise, interrupts
+        // after switching `sscratch` will mess up the CPU state.
+        crate::arch::irq::disable_local();
         unsafe { run_user(self) }
     }
 }

ostd/src/arch/x86/trap/syscall.S

@@ -22,9 +22,6 @@
     # extern "sysv64" fn syscall_return(&mut UserContext)
 .global syscall_return
 syscall_return:
-    # disable interrupt
-    cli
-
     # save callee-saved registers
     push r15
     push r14

ostd/src/arch/x86/trap/syscall.rs

@@ -96,6 +96,9 @@ impl RawUserContext {
     /// If `trap_num` is `0x100`, it will go user by `sysret` (`rcx` and `r11` are dropped),
     /// otherwise it will use `iret`.
     pub(in crate::arch) fn run(&mut self) {
+        // Return to userspace with interrupts disabled. Otherwise, interrupts
+        // after executing `swapgs` will mess up the CPU state.
+        crate::arch::irq::disable_local();
         unsafe {
             syscall_return(self);
         }