From 13032272fdd02121d10189de355af98e1a56dd7d Mon Sep 17 00:00:00 2001
From: occheung <dc@m-labs.hk>
Date: Thu, 15 Jul 2021 15:58:13 +0800
Subject: [PATCH] bootloader: add rv32 exception handler

Signed-off-by: occheung <dc@m-labs.hk>
---
 artiq/firmware/bootloader/Cargo.toml |  1 +
 artiq/firmware/bootloader/main.rs    | 10 +++++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/artiq/firmware/bootloader/Cargo.toml b/artiq/firmware/bootloader/Cargo.toml
index e89902308..5c2a54ba5 100644
--- a/artiq/firmware/bootloader/Cargo.toml
+++ b/artiq/firmware/bootloader/Cargo.toml
@@ -17,3 +17,4 @@ byteorder = { version = "1.0", default-features = false }
 crc = { version = "1.7", default-features = false }
 board_misoc = { path = "../libboard_misoc", features = ["uart_console", "smoltcp"] }
 smoltcp = { version = "0.6.0", default-features = false, features = ["ethernet", "proto-ipv4", "proto-ipv6", "socket-tcp"] }
+riscv = { version = "0.6.0", features = ["inline-asm"] }
diff --git a/artiq/firmware/bootloader/main.rs b/artiq/firmware/bootloader/main.rs
index ad6479486..bb7030051 100644
--- a/artiq/firmware/bootloader/main.rs
+++ b/artiq/firmware/bootloader/main.rs
@@ -6,8 +6,9 @@ extern crate byteorder;
 extern crate smoltcp;
 #[macro_use]
 extern crate board_misoc;
+extern crate riscv;
 
-use core::{ptr, slice};
+use core::{ptr, slice, convert::TryFrom};
 use crc::crc32;
 use byteorder::{ByteOrder, BigEndian};
 use board_misoc::{ident, cache, sdram, config, boot, mem as board_mem};
@@ -16,6 +17,7 @@ use board_misoc::slave_fpga;
 #[cfg(has_ethmac)]
 use board_misoc::{clock, ethmac, net_settings};
 use board_misoc::uart_console::Console;
+use riscv::register::{mcause, mepc};
 
 fn check_integrity() -> bool {
     extern {
@@ -517,8 +519,10 @@ pub extern fn main() -> i32 {
 }
 
 #[no_mangle]
-pub extern fn exception(vect: u32, _regs: *const u32, pc: u32, ea: u32) {
-    panic!("exception {} at PC {:#08x}, EA {:#08x}", vect, pc, ea)
+pub extern fn exception(_regs: *const u32) {
+    let pc = mepc::read();
+    let cause = mcause::read().cause();
+    panic!("{:?} at PC {:#08x}", cause, u32::try_from(pc).unwrap())
 }
 
 #[no_mangle]