Backtrace: panic handler with proper backtrace.

src/libunwind/build.rs

@@ -39,6 +39,7 @@ mod llvm_libunwind {
         let cfg = &mut cc::Build::new();
         setup_options(cfg);
         cfg.compiler("clang");
+        cfg.flag("-funwind-tables");
 
         let unwind_sources = vec![
             "Unwind-sjlj.c",

src/runtime/src/main.rs

@@ -2,6 +2,8 @@
 #![no_main]
 #![recursion_limit="1024"]  // for futures_util::select!
 #![feature(llvm_asm)]
+#![feature(alloc_error_handler)]
+#![feature(panic_info_message)]
 
 extern crate alloc;
 
@@ -24,6 +26,7 @@ mod kernel;
 mod moninj;
 mod load_pl;
 mod eh_artiq;
+mod panic;
 
 fn identifier_read(buf: &mut [u8]) -> &str {
     unsafe {

src/runtime/src/panic.rs

@@ -0,0 +1,26 @@
+use libboard_zynq::{slcr, print, println};
+use unwind::backtrace;
+
+#[panic_handler]
+fn panic(info: &core::panic::PanicInfo) -> ! {
+    print!("panic at ");
+    if let Some(location) = info.location() {
+        print!("{}:{}:{}", location.file(), location.line(), location.column());
+    } else {
+        print!("unknown location");
+    }
+    if let Some(message) = info.message() {
+        println!(": {}", message);
+    } else {
+        println!("");
+    }
+    println!("Backtrace: ");
+    let _ = backtrace(|ip| {
+        // Backtrace gives us the return address, i.e. the address after the delay slot,
+        // but we're interested in the call instruction.
+        println!("{:#08x}", ip - 2 * 4);
+    });
+    println!("End backtrace");
+    slcr::RegisterBlock::unlocked(|slcr| slcr.soft_reset());
+    loop {}
+}