feat: add Rust userspace support; fix TLS layout for p_align < 16; kill whole process on sibling-thread faults

programs/rust/montauk-rt/src/process.rs

@@ -0,0 +1,35 @@
+//! Process control.
+
+use crate::sys;
+
+unsafe extern "C" {
+    // libc exit(): runs atexit handlers (and .fini_array), then SYS_EXIT.
+    #[link_name = "exit"]
+    fn libc_exit(code: i32) -> !;
+}
+
+/// Exit the process. From a sibling thread this ends only that thread
+/// (kernel semantics); use [`abort`] to take the whole process down.
+pub fn exit(code: i32) -> ! {
+    unsafe { libc_exit(code) }
+}
+
+pub fn id() -> u32 {
+    unsafe { sys::syscall0(sys::SYS_GETPID) as u32 }
+}
+
+/// Terminate the whole process from any thread.
+pub fn abort() -> ! {
+    unsafe {
+        if crate::thread::current_id() == id() {
+            sys::syscall1(sys::SYS_EXIT, 134);
+        } else {
+            // Sibling: SYS_EXIT would end only this thread. Self-kill flags
+            // every thread; park here until the kernel reaps us.
+            sys::syscall1(sys::SYS_KILL, id() as u64);
+        }
+        loop {
+            sys::syscall0(sys::SYS_YIELD);
+        }
+    }
+}