When a trap occurs in mini-rv32ima, always pass to the host rather than allowing running code to handle it. This would be important for a real OS, but the aim of uvm32 is embeddable logic - not full emulation.

As all traps are caught by host, begin testing mini-rv32ima internals by checking PC oob and PC alignment.

test/Makefile

@@ -6,7 +6,8 @@ TESTS = \
     meter \
     extram \
     badcode \
-    invalid_opcodes
+    invalid_opcodes \
+    minirv32_internal
 
 RUNCMD = $(foreach TEST,${TESTS},make -C ${TEST} &&)
 CLEANCMD = $(foreach TEST,${TESTS},make -C ${TEST} clean &&)
@@ -14,7 +15,7 @@ CLEANCMD = $(foreach TEST,${TESTS},make -C ${TEST} clean &&)
 ifeq (,$(shell which gcovr))
 	GCOVRCMD=echo Install gcovr for code coverage reports
 else
-    GCOVRCMD=gcovr -r ../ --filter ".*uvm32.c"
+    GCOVRCMD=gcovr -r ../ --filter ".*uvm32.c" --filter ".*mini.*"
 	PERC=$(shell gcovr -r ../ --filter ".*uvm32.c" | grep uvm | awk '{print $$4}')
 endif
 

test/minirv32_internal/Makefile

@@ -0,0 +1,2 @@
+TOPDIR=../..
+include ${TOPDIR}/test/common/makefile.common

test/minirv32_internal/rom/Makefile

@@ -0,0 +1,2 @@
+TOPDIR=../../..
+include ${TOPDIR}/test/common/makefile-rom.common

test/minirv32_internal/rom/rom.c

@@ -0,0 +1,6 @@
+#include "uvm32_target.h"
+
+void main(void) {
+    println("Hello world");
+}
+

test/minirv32_internal/test/tests.c

@@ -0,0 +1,55 @@
+#include <string.h>
+#include "unity.h"
+#include "uvm32.h"
+#include "../common/uvm32_common_custom.h"
+
+#include "rom-header.h"
+
+static uvm32_state_t vmst;
+static uvm32_evt_t evt;
+
+void setUp(void) {
+    // runs before each test
+    uvm32_init(&vmst);
+    uvm32_load(&vmst, rom_bin, rom_bin_len);
+}
+
+void tearDown(void) {
+}
+
+void test_pc_too_big(void) {
+    // No code should be doing this, but...
+    TEST_ASSERT_EQUAL(0x80000000, uvm32_getProgramCounter(&vmst));
+    vmst._core.pc = 0x80000000 + 1024 * 16 * 4; // off end
+    uvm32_run(&vmst, &evt, 1);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_ERR);
+    TEST_ASSERT_EQUAL(evt.data.err.errcode, UVM32_ERR_INTERNAL_CORE);
+}
+
+void test_pc_unaligned_1(void) {
+    // No code should be doing this, but...
+    TEST_ASSERT_EQUAL(0x80000000, uvm32_getProgramCounter(&vmst));
+    vmst._core.pc = 0x80000000 + 1;
+    uvm32_run(&vmst, &evt, 1);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_ERR);
+    TEST_ASSERT_EQUAL(evt.data.err.errcode, UVM32_ERR_INTERNAL_CORE);
+}
+
+void test_pc_unaligned_2(void) {
+    // No code should be doing this, but...
+    TEST_ASSERT_EQUAL(0x80000000, uvm32_getProgramCounter(&vmst));
+    vmst._core.pc = 0x80000000 + 2;
+    uvm32_run(&vmst, &evt, 1);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_ERR);
+    TEST_ASSERT_EQUAL(evt.data.err.errcode, UVM32_ERR_INTERNAL_CORE);
+}
+
+void test_pc_unaligned_3(void) {
+    // No code should be doing this, but...
+    TEST_ASSERT_EQUAL(0x80000000, uvm32_getProgramCounter(&vmst));
+    vmst._core.pc = 0x80000000 + 3;
+    uvm32_run(&vmst, &evt, 1);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_ERR);
+    TEST_ASSERT_EQUAL(evt.data.err.errcode, UVM32_ERR_INTERNAL_CORE);
+}
+

uvm32/mini-rv32ima.h

@@ -501,6 +501,7 @@ MINIRV32_STEPPROTO
 	// Handle traps and interrupts.
 	if( trap )
 	{
+#ifndef MINIRV32_RETURN_TRAP
 		if( trap & 0x80000000 ) // If prefixed with 1 in MSB, it's an interrupt, not a trap.
 		{
 			SETCSR( mcause, trap );
@@ -520,9 +521,13 @@ MINIRV32_STEPPROTO
 
 		// If trapping, always enter machine mode.
 		CSR( extraflags ) |= 3;
-
 		trap = 0;
 		pc += 4;
+#else
+        if (trap > 0) {
+            return trap;
+        }
+#endif
 	}
 
 	if( CSR( cyclel ) > cycle ) CSR( cycleh )++;

uvm32/uvm32.h

@@ -40,6 +40,7 @@ SOFTWARE.
 
 // Setup and hooks for mini-rv32ima emulator core
 #define MINIRV32_DECORATE static
+#define MINIRV32_RETURN_TRAP
 #define MINI_RV32_RAM_SIZE UVM32_MEMORY_SIZE
 #define MINIRV32_POSTEXEC(pc, ir, retval) {if (retval > 0) return retval;}
 uint32_t _uvm32_extramLoad(void *userdata, uint32_t addr, uint32_t accessTyp);