Fix distingishing kernel/user mode cpu exceptions

kernel/hal/x86_64/intr.c

@@ -215,7 +215,7 @@ void intr_handleintr(IntrStackFrame *frame) {
     kprintf("ERROR %s, 0x%lX\n", exceptions[frame->trapnum], frame->errnum);
     intr_dumpframe(frame);
     backtrace((BackTraceFrame *)frame->regs.rbp);
-    if (frame->cs == UCODE) {
+    if (frame->cs == (UCODE | 0x3)) {
       kprintf("killed pid %ld %s\n", PROCS.current->pid, PROCS.current->name);
       proc_killself();
       proc_sched((void *)frame);