examples/rp235x: Add multicore stack overflow example

1 files changed, 72 insertions, 0 deletions

diff --git a/examples/rp235x/src/bin/multicore_stack_overflow.rs b/examples/rp235x/src/bin/multicore_stack_overflow.rs
new file mode 100644
index 000000000..dba44aa23
--- /dev/null
+++ b/examples/rp235x/src/bin/multicore_stack_overflow.rs
@@ -0,0 +1,72 @@
+//! This example tests stack overflow handling on core1 of the RP235x chip.
+
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Executor;
+use embassy_rp::gpio::{Level, Output};
+use embassy_rp::multicore::{spawn_core1, Stack};
+use embassy_time::Timer;
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+const CORE1_STACK_LENGTH: usize = 4096;
+
+static mut CORE1_STACK: Stack<CORE1_STACK_LENGTH> = Stack::new();
+static EXECUTOR0: StaticCell<Executor> = StaticCell::new();
+static EXECUTOR1: StaticCell<Executor> = StaticCell::new();
+
+#[cortex_m_rt::entry]
+fn main() -> ! {
+    let p = embassy_rp::init(Default::default());
+    let led = Output::new(p.PIN_25, Level::Low);
+
+    spawn_core1(
+        p.CORE1,
+        unsafe { &mut *core::ptr::addr_of_mut!(CORE1_STACK) },
+        move || {
+            let executor1 = EXECUTOR1.init(Executor::new());
+            executor1.run(|spawner| spawner.spawn(unwrap!(core1_task())));
+        },
+    );
+
+    let executor0 = EXECUTOR0.init(Executor::new());
+    executor0.run(|spawner| spawner.spawn(unwrap!(core0_task(led))));
+}
+
+#[embassy_executor::task]
+async fn core0_task(mut led: Output<'static>) {
+    info!("Hello from core 0");
+    loop {
+        info!("core 0 still alive");
+        led.set_high();
+        Timer::after_millis(500).await;
+        led.set_low();
+        Timer::after_millis(500).await;
+    }
+}
+
+fn blow_my_stack() {
+    // Allocating an array a little larger than our stack should ensure a stack overflow when it is used.
+    let t = [0u8; CORE1_STACK_LENGTH + 64];
+
+    info!("Array initialised without error");
+    // We need to use black_box to otherwise the compiler is too smart and will optimise all of this away.
+    // We shouldn't get to this code - the initialisation above will touch the stack guard.
+    for ref i in t {
+        let _data = core::hint::black_box(*i) + 1;
+    }
+}
+
+#[embassy_executor::task]
+async fn core1_task() {
+    info!("Hello from core 1");
+
+    blow_my_stack();
+
+    loop {
+        info!("core 1 still alive");
+        Timer::after_millis(1000).await;
+    }
+}