pbio/platform/ev3/platform.c: Offset address for abort exceptions

The actual faulting instruction for these exceptions is offset
(due to CPU pipelining in this core, later as part of compatibility).

Print the actual faulting instruction address so that the developer
doesn't have to manually subtract 8.

Author: ArcaneNibble

lib/pbio/platform/ev3/exceptionhandler.S

@@ -1,5 +1,7 @@
 @ SPDX-License-Identifier: MPL-1.0
 @ Copyright (c) 2016 Tobias Schießl
+#include "exceptionhandler.h"
+
         .set  MODE_USR, 0x10            
         .set  MODE_FIQ, 0x11
         .set  MODE_IRQ, 0x12
@@ -12,10 +14,6 @@
         .equ I_F_BIT, 0xC0 
         .equ MASK_SWI_NUM, 0xFF000000
         .equ MASK_SR_MODE, 0x1F
-        .equ EXCEPT_TYPE_UNKNOWN, 0
-        .equ EXCEPT_TYPE_UNDEF, 1
-        .equ EXCEPT_TYPE_PREFETCH_ABORT, 2
-        .equ EXCEPT_TYPE_DATA_ABORT, 3
 
         @ This will be placed at 0xffff0000 by the linker script
         .section .vector,"ax",%progbits
@@ -35,25 +33,25 @@ ResetToEntry:
 UndefHandlder:
         @ Save r0-r12, lr
         stmfd   sp!, {r0-r12, lr}
-        mov     r7, #EXCEPT_TYPE_UNDEF
+        mov     r7, #EV3_PANIC_UNDEFINED_INSTR
         b       CommonPanicHandler
 
 PrefetchAbortHandler:
         @ Save r0-r12, lr
         stmfd   sp!, {r0-r12, lr}
-        mov     r7, #EXCEPT_TYPE_PREFETCH_ABORT
+        mov     r7, #EV3_PANIC_PREFETCH_ABORT
         b       CommonPanicHandler
 
 DataAbortHandler:
         @ Save r0-r12, lr
         stmfd   sp!, {r0-r12, lr}
-        mov     r7, #EXCEPT_TYPE_DATA_ABORT
+        mov     r7, #EV3_PANIC_DATA_ABORT
         b       CommonPanicHandler
 
 UnknownExceptionHandler:
         @ Save r0-r12, lr
         stmfd   sp!, {r0-r12, lr}
-        mov     r7, #EXCEPT_TYPE_UNKNOWN
+        mov     r7, #EV3_PANIC_UNKNOWN
         @ b       CommonPanicHandler
         @ fall through
 

lib/pbio/platform/ev3/exceptionhandler.h

@@ -0,0 +1,9 @@
+#ifndef PBIO_EV3_EXCEPTIONHANDLER_H_
+#define PBIO_EV3_EXCEPTIONHANDLER_H_
+
+#define EV3_PANIC_UNKNOWN           0
+#define EV3_PANIC_UNDEFINED_INSTR   1
+#define EV3_PANIC_PREFETCH_ABORT    2
+#define EV3_PANIC_DATA_ABORT        3
+
+#endif // PBIO_EV3_EXCEPTIONHANDLER_H_

lib/pbio/platform/ev3/platform.c

@@ -59,6 +59,8 @@
 #include <pbdrv/ioport.h>
 #include <pbio/port_interface.h>
 
+#include "exceptionhandler.h"
+
 #include "../../drv/block_device/block_device_ev3.h"
 #include "../../drv/button/button_gpio.h"
 #include "../../drv/display/display_ev3.h"
@@ -417,6 +419,7 @@ static const char *const panic_types[] = {
     "Prefetch Abort",
     "Data Abort",
 };
+
 typedef struct {
     uint32_t r13;
     uint32_t r14;
@@ -481,7 +484,17 @@ void ev3_panic_handler(int except_type, ev3_panic_ctx *except_data) {
     panic_puts("\r\nR14:  0x");
     panic_putu32(except_data->r14);
     panic_puts("\r\nR15:  0x");
-    panic_putu32(except_data->exc_lr);
+    switch (except_type) {
+        case EV3_PANIC_PREFETCH_ABORT:
+            panic_putu32(except_data->exc_lr - 4);
+            break;
+        case EV3_PANIC_DATA_ABORT:
+            panic_putu32(except_data->exc_lr - 8);
+            break;
+        default:
+            panic_putu32(except_data->exc_lr);
+            break;
+    }
     panic_puts("\r\nSPSR: 0x");
     panic_putu32(except_data->spsr);