feature: spawn for closures

libsys/src/abi.rs

@@ -6,6 +6,7 @@ pub const SYS_EX_SIGRETURN: usize = 131;
 pub const SYS_EX_KILL: usize = 132;
 pub const SYS_EX_CLONE: usize = 133;
 pub const SYS_EX_YIELD: usize = 134;
+pub const SYS_EX_THREAD_EXIT: usize = 135;
 
 pub const SYS_EXIT: usize = 1;
 pub const SYS_READ: usize = 2;

libsys/src/calls.rs

@@ -283,6 +283,14 @@ pub fn sys_ex_clone(entry: usize, stack: usize, arg: usize) -> Result<usize, Err
     })
 }
 
+#[inline(always)]
+pub fn sys_ex_thread_exit(status: ExitCode) -> ! {
+    unsafe {
+        syscall!(abi::SYS_EX_THREAD_EXIT, argn!(i32::from(status)));
+    }
+    unreachable!();
+}
+
 #[inline(always)]
 pub fn sys_ex_yield() {
     unsafe {