From 00b0503594a0ad7540b649ad93d8afbad797b8ae Mon Sep 17 00:00:00 2001
From: Kor Nielsen <kor@google.com>
Date: Wed, 13 Sep 2023 14:16:51 -0700
Subject: [PATCH] ROM: Log NMI/exception details to
 CPTRA_FW_EXTENDED_ERROR_INFO. (#753)

This information is useful to debug unexpected ROM or hardware failures.
---
 drivers/src/soc_ifc.rs | 13 ------------
 rom/dev/src/main.rs    | 46 +++++++++++++++++++++++++++++++++++++-----
 2 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/drivers/src/soc_ifc.rs b/drivers/src/soc_ifc.rs
index eeb623323b..197c57fd2a 100644
--- a/drivers/src/soc_ifc.rs
+++ b/drivers/src/soc_ifc.rs
@@ -14,7 +14,6 @@ Abstract:
 
 use caliptra_error::{CaliptraError, CaliptraResult};
 use caliptra_registers::soc_ifc::enums::DeviceLifecycleE;
-use caliptra_registers::soc_ifc::regs::CptraWdtStatusReadVal;
 use caliptra_registers::soc_ifc::{self, SocIfcReg};
 
 use crate::{memory_layout, FuseBank};
@@ -164,18 +163,6 @@ impl SocIfc {
             .write(|w| w.timer1_en(false));
     }
 
-    /// Get the WDT status.
-    ///
-    /// This is useful to call from a fatal-error-handling routine.
-    ///
-    ///  # Safety
-    ///
-    /// This function is safe to call from a trap handler.
-    pub unsafe fn wdt_status() -> CptraWdtStatusReadVal {
-        let soc_ifc = SocIfcReg::new();
-        soc_ifc.regs().cptra_wdt_status().read()
-    }
-
     pub fn get_cycle_count(&self, seconds: u32) -> CaliptraResult<u64> {
         const GIGA_UNIT: u32 = 1_000_000_000;
         let clock_period_picosecs = self.soc_ifc.regs().cptra_timer_config().read();
diff --git a/rom/dev/src/main.rs b/rom/dev/src/main.rs
index 12811bcea4..bb0c51cd57 100644
--- a/rom/dev/src/main.rs
+++ b/rom/dev/src/main.rs
@@ -17,6 +17,7 @@ Abstract:
 
 use crate::{lock::lock_registers, print::HexBytes};
 use caliptra_cfi_lib::CfiCounter;
+use caliptra_registers::soc_ifc::SocIfcReg;
 use core::hint::black_box;
 
 use caliptra_drivers::{
@@ -217,29 +218,64 @@ fn launch_fmc(env: &mut RomEnv) -> ! {
 #[inline(never)]
 extern "C" fn exception_handler(exception: &exception::ExceptionRecord) {
     cprintln!(
-        "EXCEPTION mcause=0x{:08X} mscause=0x{:08X} mepc=0x{:08X}",
+        "EXCEPTION mcause=0x{:08X} mscause=0x{:08X} mepc=0x{:08X} ra=0x{:08X}",
         exception.mcause,
         exception.mscause,
-        exception.mepc
+        exception.mepc,
+        exception.ra
     );
 
+    {
+        let mut soc_ifc = unsafe { SocIfcReg::new() };
+        let soc_ifc = soc_ifc.regs_mut();
+        let ext_info = soc_ifc.cptra_fw_extended_error_info();
+        ext_info.at(0).write(|_| exception.mcause);
+        ext_info.at(1).write(|_| exception.mscause);
+        ext_info.at(2).write(|_| exception.mepc);
+        ext_info.at(3).write(|_| exception.ra);
+    }
+
     handle_fatal_error(CaliptraError::ROM_GLOBAL_EXCEPTION.into());
 }
 
 #[no_mangle]
 #[inline(never)]
 extern "C" fn nmi_handler(exception: &exception::ExceptionRecord) {
+    let mut soc_ifc = unsafe { SocIfcReg::new() };
+
+    // If the NMI was fired by caliptra instead of the uC, this register
+    // contains the reason(s)
+    let err_interrupt_status = u32::from(
+        soc_ifc
+            .regs()
+            .intr_block_rf()
+            .error_internal_intr_r()
+            .read(),
+    );
+
     cprintln!(
-        "NMI mcause=0x{:08X} mscause=0x{:08X} mepc=0x{:08X}",
+        "NMI mcause=0x{:08X} mscause=0x{:08X} mepc=0x{:08X} ra=0x{:08X} error_internal_intr_r={:08X}",
         exception.mcause,
         exception.mscause,
-        exception.mepc
+        exception.mepc,
+        exception.ra,
+        err_interrupt_status,
     );
 
+    {
+        let soc_ifc = soc_ifc.regs_mut();
+        let ext_info = soc_ifc.cptra_fw_extended_error_info();
+        ext_info.at(0).write(|_| exception.mcause);
+        ext_info.at(1).write(|_| exception.mscause);
+        ext_info.at(2).write(|_| exception.mepc);
+        ext_info.at(3).write(|_| exception.ra);
+        ext_info.at(4).write(|_| err_interrupt_status);
+    }
+
     // Check if the NMI was due to WDT expiry.
     let mut error = CaliptraError::ROM_GLOBAL_NMI;
 
-    let wdt_status = unsafe { SocIfc::wdt_status() };
+    let wdt_status = soc_ifc.regs().cptra_wdt_status().read();
     if wdt_status.t1_timeout() || wdt_status.t2_timeout() {
         cprintln!("WDT Expired");
         error = CaliptraError::ROM_GLOBAL_WDT_EXPIRED;