Extract OS-specific part from UserContextApi

kernel/aster-nix/src/cpu.rs

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: MPL-2.0
+
+pub trait LinuxAbi {
+    /// Get number of syscall
+    fn syscall_num(&self) -> usize;
+
+    /// Get return value of syscall
+    fn syscall_ret(&self) -> usize;
+
+    /// Set return value of syscall
+    fn set_syscall_ret(&mut self, ret: usize);
+
+    /// Get syscall args
+    fn syscall_args(&self) -> [usize; 6];
+
+    /// Set thread-local storage pointer
+    fn set_tls_pointer(&mut self, tls: usize);
+
+    /// Get thread-local storage pointer
+    fn tls_pointer(&self) -> usize;
+}