target-lm32: stop VM on illegal or unknown instruction

Instead of translating the instruction to a no-op, pause the VM and display
a message to the user.

As a side effect, this also works for instructions where the operands are
only known at runtime.

Signed-off-by: Michael Walle <michael@walle.cc>

1 files changed, 17 insertions, 0 deletions

diff --git a/target-lm32/op_helper.c b/target-lm32/op_helper.c
index 71f21d1..7189cb5 100644
--- a/target-lm32/op_helper.c
+++ b/target-lm32/op_helper.c
@@ -8,6 +8,10 @@
 
 #include "exec/softmmu_exec.h"
 
+#ifndef CONFIG_USER_ONLY
+#include "sysemu/sysemu.h"
+#endif
+
 #if !defined(CONFIG_USER_ONLY)
 #define MMUSUFFIX _mmu
 #define SHIFT 0
@@ -39,6 +43,19 @@ void HELPER(hlt)(CPULM32State *env)
     cpu_loop_exit(env);
 }
 
+void HELPER(ill)(CPULM32State *env)
+{
+#ifndef CONFIG_USER_ONLY
+    CPUState *cs = CPU(lm32_env_get_cpu(env));
+    fprintf(stderr, "VM paused due to illegal instruction. "
+            "Connect a debugger or switch to the monitor console "
+            "to find out more.\n");
+    qemu_system_vmstop_request(RUN_STATE_PAUSED);
+    cs->halted = 1;
+    raise_exception(env, EXCP_HALTED);
+#endif
+}
+
 void HELPER(wcsr_bp)(CPULM32State *env, uint32_t bp, uint32_t idx)
 {
     uint32_t addr = bp & ~1;