feat(panic): resolve deadlock when panicking while printing

src/arch/x86_64/kernel/interrupts.rs

@@ -373,17 +373,17 @@ impl IrqStatistics {
 }
 
 pub(crate) fn print_statistics() {
-	println!("Number of interrupts");
+	panic_println!("Number of interrupts");
 	for (core_id, irg_statistics) in IRQ_COUNTERS.lock().iter() {
 		for (i, counter) in irg_statistics.counters.iter().enumerate() {
 			let counter = counter.load(Ordering::Relaxed);
 			if counter > 0 {
 				match get_irq_name(i.try_into().unwrap()) {
 					Some(name) => {
-						println!("[{core_id}][{name}]: {counter}");
+						panic_println!("[{core_id}][{name}]: {counter}");
 					}
 					_ => {
-						println!("[{core_id}][{i}]: {counter}");
+						panic_println!("[{core_id}][{i}]: {counter}");
 					}
 				}
 			}

src/console.rs

@@ -1,4 +1,4 @@
-use core::fmt;
+use core::{fmt, mem};
 
 use hermit_sync::{InterruptTicketMutex, Lazy};
 
@@ -44,6 +44,14 @@ pub fn _print(args: fmt::Arguments<'_>) {
 	CONSOLE.lock().write_fmt(args).unwrap();
 }
 
+#[doc(hidden)]
+pub fn _panic_print(args: fmt::Arguments<'_>) {
+	use fmt::Write;
+	let mut console = unsafe { CONSOLE.make_guard_unchecked() };
+	console.write_fmt(args).ok();
+	mem::forget(console);
+}
+
 #[cfg(all(test, not(target_os = "none")))]
 mod tests {
 	use super::*;

src/lib.rs

@@ -262,7 +262,7 @@ fn application_processor_main() -> ! {
 #[panic_handler]
 fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
 	let core_id = crate::arch::core_local::core_id();
-	println!("[{core_id}][PANIC] {info}");
+	panic_println!("[{core_id}][PANIC] {info}\n");
 
 	crate::scheduler::shutdown(1);
 }

src/macros.rs

@@ -27,6 +27,18 @@ macro_rules! println {
     }};
 }
 
+/// Emergency output.
+#[cfg(target_os = "none")]
+#[macro_export]
+macro_rules! panic_println {
+    () => {
+        $crate::console::_panic_print(::core::format_args!("\n"));
+    };
+    ($($arg:tt)*) => {{
+        $crate::console::_panic_print(::core::format_args!("{}\n", format_args!($($arg)*)));
+    }};
+}
+
 /// Prints and returns the value of a given expression for quick and dirty
 /// debugging.
 // Copied from std/macros.rs

src/syscalls/interfaces/mod.rs

@@ -50,7 +50,7 @@ pub trait SyscallInterface: Send + Sync {
 
 	fn shutdown(&self, error_code: i32) -> ! {
 		// This is a stable message used for detecting exit codes for different hypervisors.
-		println!("exit status {error_code}");
+		panic_println!("exit status {error_code}");
 
 		arch::processor::shutdown(error_code)
 	}