From 25eb06c08966986192ab498717d5617abba193b4 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge.aparicio@ferrous-systems.com>
Date: Mon, 7 Sep 2020 19:09:36 +0200
Subject: [PATCH] add stack overflow protection

---
 .cargo/config.toml  |  1 +
 src/bin/overflow.rs | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 src/bin/overflow.rs

diff --git a/.cargo/config.toml b/.cargo/config.toml
index a6fd2d5..c549fd0 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -2,6 +2,7 @@
 # TODO(2) replace `$CHIP` with your chip's name (see `probe-run --list-chips` output)
 runner = "probe-run --chip $CHIP --defmt"
 rustflags = [
+  "-C", "linker=flip-link",
   "-C", "link-arg=-Tlink.x",
   "-C", "link-arg=-Tdefmt.x",
 ]
diff --git a/src/bin/overflow.rs b/src/bin/overflow.rs
new file mode 100644
index 0000000..03c2a47
--- /dev/null
+++ b/src/bin/overflow.rs
@@ -0,0 +1,25 @@
+#![no_main]
+#![no_std]
+
+use {{crate_name}} as _; // global logger + panicking-behavior + memory layout
+
+#[cortex_m_rt::entry]
+fn main() -> ! {
+    ack(10, 10);
+    {{crate_name}}::exit()
+}
+
+fn ack(m: u32, n: u32) -> u32 {
+    defmt::info!("ack(m={:u32}, n={:u32})", m, n);
+    let mut big = [2; 512];
+    if m == 0 {
+        n + 1
+    } else {
+        big[100] += 1;
+        if n == 0 {
+            ack(m - 1, 1)
+        } else {
+            ack(m - 1, ack(m, n - 1))
+        }
+    }
+}