From 905330b0f1c5ba19ca27b55be881e89067e2e57b Mon Sep 17 00:00:00 2001
From: occheung <dc@m-labs.hk>
Date: Wed, 11 Aug 2021 12:20:41 +0800
Subject: [PATCH] ksupport: handle riscv exceptions

---
 artiq/firmware/ksupport/Cargo.toml |  2 +-
 artiq/firmware/ksupport/lib.rs     | 10 +++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/artiq/firmware/ksupport/Cargo.toml b/artiq/firmware/ksupport/Cargo.toml
index ba53a7c9a..fbedbd792 100644
--- a/artiq/firmware/ksupport/Cargo.toml
+++ b/artiq/firmware/ksupport/Cargo.toml
@@ -19,4 +19,4 @@ io = { path = "../libio", features = ["byteorder"] }
 dyld = { path = "../libdyld" }
 board_misoc = { path = "../libboard_misoc" }
 board_artiq = { path = "../libboard_artiq" }
-proto_artiq = { path = "../libproto_artiq" }
+riscv = { version = "0.6.0", features = ["inline-asm"] }
diff --git a/artiq/firmware/ksupport/lib.rs b/artiq/firmware/ksupport/lib.rs
index 5e42fd100..b4a430289 100644
--- a/artiq/firmware/ksupport/lib.rs
+++ b/artiq/firmware/ksupport/lib.rs
@@ -12,8 +12,9 @@ extern crate dyld;
 extern crate board_misoc;
 extern crate board_artiq;
 extern crate proto_artiq;
+extern crate riscv;
 
-use core::{mem, ptr, slice, str};
+use core::{mem, ptr, slice, str, convert::TryFrom};
 use cslice::{CSlice, AsCSlice};
 use io::Cursor;
 use dyld::Library;
@@ -22,6 +23,7 @@ use proto_artiq::{kernel_proto, rpc_proto};
 use kernel_proto::*;
 #[cfg(has_rtio_dma)]
 use board_misoc::csr;
+use riscv::register::{mcause, mepc};
 
 fn send(request: &Message) {
     unsafe { mailbox::send(request as *const _ as usize) }
@@ -519,8 +521,10 @@ pub unsafe fn main() {
 
 #[no_mangle]
 #[unwind(allowed)]
-pub extern fn exception(vect: u32, _regs: *const u32, pc: u32, ea: u32) {
-    panic!("exception {:?} at PC 0x{:x}, EA 0x{:x}", 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]