Reduce dead code, fix aarch64.

src/context/arch/x86_64.rs

@@ -3,12 +3,10 @@ use core::{
     sync::atomic::AtomicBool,
 };
 
-use crate::{percpu::PercpuBlock, ptrace, syscall::FloatRegisters};
+use crate::syscall::FloatRegisters;
 
 use core::mem::offset_of;
-use alloc::sync::Arc;
 use spin::Once;
-use syscall::PtraceFlags;
 use x86::msr;
 
 /// This must be used by the kernel to ensure that context switches are done atomically

src/context/signal.rs

@@ -5,7 +5,7 @@ use syscall::{
         PTRACE_FLAG_IGNORE, PTRACE_STOP_SIGNAL, SIGCHLD, SIGCONT, SIGKILL, SIGSTOP, SIGTSTP,
         SIGTTIN, SIGTTOU, SIG_DFL, SIG_IGN,
     },
-    ptrace_event, SignalStack, SigActionFlags, IntRegisters, Error, EINTR, SIGTERM,
+    ptrace_event, SignalStack, SigActionFlags, IntRegisters, SIGTERM,
 };
 
 use crate::{