Fix the CI issues with static mut access (#763)

- [x] no changelog update needed

agb/src/interrupt.rs

@@ -4,7 +4,7 @@ use alloc::boxed::Box;
 use critical_section::{CriticalSection, RawRestoreState};
 use portable_atomic::{AtomicBool, AtomicUsize, Ordering};
 
-use crate::{display::DISPLAY_STATUS, memory_mapped::MemoryMapped};
+use crate::{display::DISPLAY_STATUS, memory_mapped::MemoryMapped, util::SyncUnsafeCell};
 
 #[derive(Clone, Copy)]
 pub enum Interrupt {
@@ -123,7 +123,7 @@ impl InterruptRoot {
     }
 }
 
-static mut INTERRUPT_TABLE: [InterruptRoot; 14] = [
+static INTERRUPT_TABLE: SyncUnsafeCell<[InterruptRoot; 14]> = SyncUnsafeCell::new([
     InterruptRoot::new(Interrupt::VBlank),
     InterruptRoot::new(Interrupt::HBlank),
     InterruptRoot::new(Interrupt::VCounter),
@@ -138,11 +138,12 @@ static mut INTERRUPT_TABLE: [InterruptRoot; 14] = [
     InterruptRoot::new(Interrupt::Dma3),
     InterruptRoot::new(Interrupt::Keypad),
     InterruptRoot::new(Interrupt::Gamepak),
-];
+]);
 
 #[no_mangle]
-extern "C" fn __RUST_INTERRUPT_HANDLER(interrupt: u16) -> u16 {
-    for (i, root) in unsafe { INTERRUPT_TABLE.iter().enumerate() } {
+#[export_name = "__RUST_INTERRUPT_HANDLER"]
+extern "C" fn interrupt_handler(interrupt: u16) -> u16 {
+    for (i, root) in unsafe { &mut *INTERRUPT_TABLE.get() }.iter().enumerate() {
         if (1 << i) & interrupt != 0 {
             root.trigger_interrupts();
         }
@@ -219,8 +220,8 @@ impl InterruptRoot {
     }
 }
 
-fn interrupt_to_root(interrupt: Interrupt) -> &'static InterruptRoot {
-    unsafe { &INTERRUPT_TABLE[interrupt as usize] }
+unsafe fn interrupt_to_root(interrupt: Interrupt) -> &'static InterruptRoot {
+    &(unsafe { &mut *INTERRUPT_TABLE.get() })[interrupt as usize]
 }
 
 #[must_use]
@@ -259,7 +260,7 @@ pub unsafe fn add_interrupt_handler(
 ) -> InterruptHandler {
     fn do_with_inner(interrupt: Interrupt, inner: Pin<Box<InterruptInner>>) -> InterruptHandler {
         critical_section::with(|_| {
-            let root = interrupt_to_root(interrupt);
+            let root = unsafe { interrupt_to_root(interrupt) };
             root.add();
             let mut c = root.next.get();
             if c.is_null() {
@@ -373,7 +374,7 @@ mod tests {
     #[test_case]
     fn test_interrupt_table_length(_gba: &mut crate::Gba) {
         assert_eq!(
-            unsafe { INTERRUPT_TABLE.len() },
+            unsafe { (*INTERRUPT_TABLE.get()).len() },
             Interrupt::Gamepak as usize + 1,
             "interrupt table should be able to store gamepak interrupt"
         );

agb/src/lib.rs

@@ -190,6 +190,7 @@ mod sync;
 pub mod syscall;
 /// Interactions with the internal timers
 pub mod timer;
+pub(crate) mod util;
 
 mod no_game;
 
@@ -326,6 +327,8 @@ impl Gba {
 /// You can run the tests using `cargo test`, but it will work better through `mgba-test-runner` by
 /// running something along the lines of `CARGO_TARGET_THUMBV4T_NONE_EABI_RUNNER=mgba-test-runner cargo test`.
 pub mod test_runner {
+    use util::SyncUnsafeCell;
+
     use super::*;
 
     #[doc(hidden)]
@@ -373,7 +376,7 @@ pub mod test_runner {
         }
     }
 
-    static mut TEST_GBA: Option<Gba> = None;
+    static TEST_GBA: SyncUnsafeCell<Option<Gba>> = SyncUnsafeCell::new(None);
 
     #[doc(hidden)]
     pub fn test_runner(tests: &[&dyn Testable]) {
@@ -384,7 +387,7 @@ pub mod test_runner {
         )
         .unwrap();
 
-        let gba = unsafe { TEST_GBA.as_mut() }.unwrap();
+        let gba = unsafe { &mut *TEST_GBA.get() }.as_mut().unwrap();
 
         for test in tests {
             test.run(gba);
@@ -414,7 +417,7 @@ pub mod test_runner {
 
     #[doc(hidden)]
     pub fn agb_start_tests(gba: Gba, test_main: impl Fn()) -> ! {
-        unsafe { TEST_GBA = Some(gba) };
+        *unsafe { &mut *TEST_GBA.get() } = Some(gba);
         test_main();
         #[allow(clippy::empty_loop)]
         loop {}

agb/src/util.rs

@@ -0,0 +1,16 @@
+use core::cell::UnsafeCell;
+
+pub struct SyncUnsafeCell<T>(UnsafeCell<T>);
+
+unsafe impl<T> Sync for SyncUnsafeCell<T> {}
+unsafe impl<T> Send for SyncUnsafeCell<T> {}
+
+impl<T> SyncUnsafeCell<T> {
+    pub const fn new(t: T) -> Self {
+        Self(UnsafeCell::new(t))
+    }
+
+    pub unsafe fn get(&self) -> *mut T {
+        self.0.get()
+    }
+}

emulator/mgba-sys/src/lib.rs

@@ -1,6 +1,7 @@
 #[allow(non_upper_case_globals)]
 #[allow(non_camel_case_types)]
 #[allow(non_snake_case)]
+#[allow(improper_ctypes)]
 mod ffi {
     include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
 }