Add support for .init_array

Signed-off-by: Nick Spinale <[email protected]>

crates/private/support/sel4-simple-task/runtime/src/lib.rs

@@ -79,6 +79,7 @@ pub unsafe extern "C" fn cont_fn(cont_arg: *mut sel4_runtime_common::ContArg) ->
         CONFIG.set(config.clone()).unwrap();
         sel4_runtime_common::set_eh_frame_finder().unwrap();
         sel4_panicking::set_hook(&panic_hook);
+        sel4_runtime_common::run_ctors();
         __sel4_simple_task_main(config.arg());
     } else {
         let endpoint = Endpoint::from_bits(thread_config.endpoint().unwrap());

crates/sel4-microkit/src/entry.rs

@@ -39,6 +39,7 @@ fn inner_entry() -> ! {
 
     unsafe {
         sel4::set_ipc_buffer(get_ipc_buffer());
+        sel4_runtime_common::run_ctors();
         __sel4_microkit__main();
     }
 

crates/sel4-root-task/src/lib.rs

@@ -48,6 +48,7 @@ fn inner_entry(bootinfo: *const sel4::sys::seL4_BootInfo) -> ! {
     unsafe {
         let bootinfo = sel4::BootInfo::from_ptr(bootinfo);
         sel4::set_ipc_buffer(bootinfo.ipc_buffer());
+        sel4_runtime_common::run_ctors();
         __sel4_root_task__main(&bootinfo);
     }
 

crates/sel4-runtime-common/src/ctors.rs

@@ -0,0 +1,39 @@
+//
+// Copyright 2024, Colias Group, LLC
+//
+// SPDX-License-Identifier: BSD-2-Clause
+//
+
+use core::mem;
+use core::ptr;
+use core::slice;
+
+use sel4_panicking_env::abort;
+
+type Ctor = unsafe extern "C" fn();
+
+extern "C" {
+    static __init_array_start: Ctor;
+    static __init_array_end: Ctor;
+}
+
+pub unsafe fn run_ctors() {
+    let start = ptr::addr_of!(__init_array_start);
+    let end = ptr::addr_of!(__init_array_end);
+
+    // Cast to usize for comparison, otherwise rustc seems to apply an erroneous optimization
+    // assuming __init_array_start != __init_array_end.
+    if start as usize != end as usize {
+        if start.align_offset(mem::size_of::<Ctor>()) != 0
+            || end.align_offset(mem::size_of::<Ctor>()) != 0
+        {
+            abort!("'.init_array' section is not properly aligned");
+        }
+
+        let len = (end as usize - start as usize) / mem::size_of::<Ctor>();
+        let ctors = slice::from_raw_parts(start, len);
+        for ctor in ctors {
+            (ctor)();
+        }
+    }
+}

crates/sel4-runtime-common/src/lib.rs

@@ -7,6 +7,10 @@
 #![no_std]
 #![feature(cfg_target_thread_local)]
 
+mod ctors;
+
+pub use ctors::run_ctors;
+
 #[cfg(feature = "start")]
 mod start;