Catch faults

Proof of concept for trapping faults in addition to DebugMon.

Author: adamgreen

libraries/ThreadMRI/examples/ThreadMRI/tests.S

@@ -72,6 +72,9 @@ testContext:
     mov     r10, #10
     mov     r11, #11
     mov     r12, #12
+    // Crash on read from invalid memory.
+    ldr     r0, =0xFFFFFFF0
+    ldr     r0, [r0]
     // Hardcoded breakpoint.
     bkpt    #0
     // Infinite loop.

libraries/ThreadMRI/src/ThreadMRI.cpp

@@ -324,13 +324,23 @@ static void setHandlerPriorityLowerThanDebugger(IRQn_Type irq, uint32_t origPrio
 static void switchFaultHandlersToDebugger();
 #endif // UNDONE
 
+// Forward Function Declarations
+static void switchFaultHandlersToDebugger();
+
 
 static void mriDebugMonitorHandler(void)
 {
     g_haltingThreadId = osThreadGetId();
     osThreadFlagsSet(g_mriThreadId, MRI_THREAD_DEBUG_EVENT_FLAG);
 }
 
+static void mriFaultHandler(void)
+{
+    g_haltingThreadId = osThreadGetId();
+    osThreadFlagsSet(g_mriThreadId, MRI_THREAD_DEBUG_EVENT_FLAG);
+}
+
+
 void Platform_Init(Token* pParameterTokens)
 {
 #ifdef UNDONE
@@ -349,8 +359,8 @@ void Platform_Init(Token* pParameterTokens)
     g_pDebugSerial->setSerialPriority(0);
     NVIC_SetPriority(DebugMonitor_IRQn, 1);
 
-    switchFaultHandlersToDebugger();
 #endif // UNDONE
+    switchFaultHandlersToDebugger();
     NVIC_SetVector(DebugMonitor_IRQn, (uint32_t)mriDebugMonitorHandler);
     enableDWTandITM();
     initDWT();
@@ -399,14 +409,14 @@ static void setHandlerPriorityLowerThanDebugger(IRQn_Type irq, uint32_t priority
     }
     NVIC_SetPriority(irq, priority);
 }
+#endif // UNDONE
 
 static void switchFaultHandlersToDebugger(void) {
-    NVIC_SetVector(HardFault_IRQn,        (uint32_t)&mriFaultHandler);
-    NVIC_SetVector(MemoryManagement_IRQn, (uint32_t)&mriFaultHandler);
-    NVIC_SetVector(BusFault_IRQn,         (uint32_t)&mriFaultHandler);
-    NVIC_SetVector(UsageFault_IRQn,       (uint32_t)&mriExceptionHandler);
+    NVIC_SetVector(HardFault_IRQn,        (uint32_t)mriFaultHandler);
+    NVIC_SetVector(MemoryManagement_IRQn, (uint32_t)mriFaultHandler);
+    NVIC_SetVector(BusFault_IRQn,         (uint32_t)mriFaultHandler);
+    NVIC_SetVector(UsageFault_IRQn,       (uint32_t)mriFaultHandler);
 }
-#endif // UNDONE
 
 uint32_t Platform_CommHasReceiveData(void)
 {