risc-v support for defmt-test

CHANGELOG.md

@@ -8,8 +8,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## [Unreleased]
 
 - [#789]: `defmt`: Add support for new time-related display hints
+- [#796]: `panic-probe`: Add riscv32 support, `print-log` feature and employ critical-section on panic.
 
 [#789]: https://github.com/knurling-rs/defmt/pull/789
+[#796]: https://github.com/knurling-rs/defmt/pull/796
 
 ## defmt-decoder v0.3.9, defmt-print v0.3.10 - 2023-10-04
 

firmware/defmt-test/CHANGELOG.md

@@ -1,5 +1,9 @@
 # [Unreleased]
 
+- [#796] Add support for risc-v, but do no longer import the cortex-m exception handlers
+
+[#796]: https://github.com/knurling-rs/defmt/pull/796
+
 # [v0.3.1]
 
 - [#786]: `defmt-test`: Exit with semihosting exit

firmware/defmt-test/Cargo.toml

@@ -11,7 +11,6 @@ repository = "https://github.com/knurling-rs/defmt"
 version = "0.3.1"
 
 [dependencies]
-cortex-m-rt = "0.7"
-cortex-m-semihosting = "0.5"
+semihosting = "0.1.4"
 defmt = { version = "0.3", path = "../../defmt" }
 defmt-test-macros = { version = "=0.3.0", path = "macros" }

firmware/defmt-test/src/export.rs

@@ -1,15 +1,11 @@
-use cortex_m_rt as _;
-use cortex_m_semihosting::debug;
 pub use defmt::info;
 
 use crate::TestOutcome;
 
 /// Terminates the application and makes a semihosting-capable debug tool exit
 /// with status code 0.
 pub fn exit() -> ! {
-    loop {
-        debug::exit(debug::EXIT_SUCCESS);
-    }
+    semihosting::process::exit(0);
 }
 
 pub fn check_outcome<T: TestOutcome>(outcome: T, should_error: bool) {

firmware/panic-probe/Cargo.toml

@@ -1,26 +1,30 @@
 [package]
 authors = ["The Knurling Authors"]
 categories = ["embedded", "no-std"]
-description = "Panic handler that exits `probe-run` with an error code"
+description = "Panic handler that exits `probe-rs` with an error code"
 edition = "2021"
-keywords = ["knurling", "panic-impl", "defmt", "probe-run"]
+keywords = ["knurling", "panic-impl", "defmt", "probe-rs"]
 license = "MIT OR Apache-2.0"
 name = "panic-probe"
 readme = "README.md"
 repository = "https://github.com/knurling-rs/defmt"
 version = "0.3.1"
 
 [dependencies]
-cortex-m = "0.7"
+critical-section = "1.1.2"
 defmt = { version = "0.3", path = "../../defmt", optional = true }
+log = { version = "0.4", optional = true }
 rtt-target = { version = "0.4", optional = true }
+semihosting = "0.1.4"
 
 
 [features]
 # Print the panic message using `rtt-target`.
 print-rtt = ["rtt-target"]
 # Print the panic message using `defmt`.
 print-defmt = ["defmt", "defmt-error"]
+# Print the panic message using `log`
+print-log = ["log"]
 
 defmt-error = [] # internal feature, do not use
 

firmware/panic-probe/README.md

@@ -1,13 +1,13 @@
 # `panic-probe`
 
-> Panic handler that exits [`probe-run`] with an error code
+> Panic handler that exits [`probe-rs`] with an error code using semihosting::process::abort.
 
-[`probe-run`]: https://github.com/knurling-rs/probe-run
+[`probe-rs`]: https://github.com/probe-rs/probe-rs
 
-`panic-probe` can optionally log the panic message using the [`defmt`] logging framework.
-This functionality can be enabled through the `print-defmt` Cargo feature.
-
-[`defmt`]: https://github.com/knurling-rs/defmt
+`panic-probe` can optionally log the panic message. Enable one of the following features for that:
+* `print-defmt` to print via `defmt::error!(..)`
+* `print-log` to print via `log::error!(..)`
+* `print-rtt` to print via `rtt_target::rprintln(..)`
 
 ## Support
 

firmware/panic-probe/src/lib.rs

@@ -1,8 +1,8 @@
-//! Panic handler for `probe-run`.
+//! Panic handler for `probe-rs`.
 //!
-//! When this panic handler is used, panics will make `probe-run` print a backtrace and exit with a
-//! non-zero status code, indicating failure. This building block can be used to run on-device
-//! tests.
+//! When this panic handler is used, panics will make `probe-rs` print a backtrace (by triggering a semihosting::process::abort).
+//! Probe-rs will then exit with a non-zero status code, indicating failure.
+//! This building block can be used to run on-device tests.
 //!
 //! # Panic Messages
 //!
@@ -20,8 +20,8 @@
 #![cfg(target_os = "none")]
 #![doc(html_logo_url = "https://knurling.ferrous-systems.com/knurling_logo_light_text.svg")]
 
-#[cfg(not(cortex_m))]
-compile_error!("`panic-probe` only supports Cortex-M targets (thumbvN-none-eabi[hf])");
+#[cfg(all(not(cortex_m), not(target_arch = "riscv32")))]
+compile_error!("`panic-probe` only supports Cortex-M targets or riscv32");
 
 // Functionality `cfg`d out on platforms with OS/libstd.
 #[cfg(target_os = "none")]
@@ -35,27 +35,29 @@ mod imp {
     #[cfg(feature = "print-defmt")]
     use crate::print_defmt::print;
 
-    #[cfg(not(any(feature = "print-rtt", feature = "print-defmt")))]
+    #[cfg(feature = "print-log")]
+    use crate::print_log::print;
+
+    #[cfg(not(any(feature = "print-rtt", feature = "print-defmt", feature = "print-log")))]
     fn print(_: &core::panic::PanicInfo) {}
 
     #[panic_handler]
     fn panic(info: &PanicInfo) -> ! {
-        static PANICKED: AtomicBool = AtomicBool::new(false);
-
-        cortex_m::interrupt::disable();
-
-        // Guard against infinite recursion, just in case.
-        if !PANICKED.load(Ordering::Relaxed) {
-            PANICKED.store(true, Ordering::Relaxed);
+        critical_section::with(|_| {
+            // Guard against infinite recursion, just in case.
+            static PANICKED: AtomicBool = AtomicBool::new(false);
+            if !PANICKED.load(Ordering::Relaxed) {
+                PANICKED.store(true, Ordering::Relaxed);
 
-            print(info);
-        }
+                print(info);
+            }
 
-        crate::hard_fault();
+            crate::abort() // this call will never return, therefore we stay in the critical section forever.
+        })
     }
 }
 
-/// Trigger a `HardFault` via `udf` instruction.
+/// Triggers a semihosting::process::abort
 ///
 /// This function may be used to as `defmt::panic_handler` to avoid double prints.
 ///
@@ -64,26 +66,12 @@ mod imp {
 /// ```
 /// #[defmt::panic_handler]
 /// fn panic() -> ! {
-///     panic_probe::hard_fault();
+///     panic_probe::abort();
 /// }
 /// ```
 #[cfg(target_os = "none")]
-pub fn hard_fault() -> ! {
-    // If `UsageFault` is enabled, we disable that first, since otherwise `udf` will cause that
-    // exception instead of `HardFault`.
-    #[cfg(not(any(armv6m, armv8m_base)))]
-    {
-        const SHCSR: *mut u32 = 0xE000ED24usize as _;
-        const USGFAULTENA: usize = 18;
-
-        unsafe {
-            let mut shcsr = core::ptr::read_volatile(SHCSR);
-            shcsr &= !(1 << USGFAULTENA);
-            core::ptr::write_volatile(SHCSR, shcsr);
-        }
-    }
-
-    cortex_m::asm::udf();
+pub fn abort() -> ! {
+    semihosting::process::abort();
 }
 
 #[cfg(feature = "print-rtt")]
@@ -104,3 +92,12 @@ mod print_defmt {
         defmt::error!("{}", defmt::Display2Format(info));
     }
 }
+
+#[cfg(feature = "print-log")]
+mod print_log {
+    use core::panic::PanicInfo;
+
+    pub fn print(info: &PanicInfo) {
+        log::error!("{}", info);
+    }
+}

firmware/qemu/tests/defmt-test.rs

@@ -3,6 +3,7 @@
 
 use core::sync::atomic::{AtomicBool, Ordering};
 
+use cortex_m_rt as _; // exception handlers
 use defmt_semihosting as _; // global logger
 
 static MAY_PANIC: AtomicBool = AtomicBool::new(false);