target/nios2: Stop generating code if gen_check_supervisor fails

Whether the cpu is in user-mode or not is something that we
know at translation-time.  We do not need to generate code
after having raised an exception.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-15-richard.henderson@linaro.org>

diff --git a/target/nios2/translate.c b/target/nios2/translate.c
index eb97e13febfa2b379fc7b8c140aef7b7c1835262..d61e349207dc2daf7075c62b3d03c6bc55ebc2df 100644 (file)
--- a/target/nios2/translate.c
+++ b/target/nios2/translate.c
@@ -169,12 +169,14 @@ static void gen_excp(DisasContext *dc, uint32_t code, uint32_t flags)
     t_gen_helper_raise_exception(dc, flags);
 }
 
-static void gen_check_supervisor(DisasContext *dc)
+static bool gen_check_supervisor(DisasContext *dc)
 {
     if (dc->base.tb->flags & CR_STATUS_U) {
         /* CPU in user mode, privileged instruction called, stop. */
         t_gen_helper_raise_exception(dc, EXCP_SUPERI);
+        return false;
     }
+    return true;
 }
 
 /*
@@ -384,7 +386,9 @@ static const Nios2Instruction i_type_instructions[] = {
  */
 static void eret(DisasContext *dc, uint32_t code, uint32_t flags)
 {
-    gen_check_supervisor(dc);
+    if (!gen_check_supervisor(dc)) {
+        return;
+    }
 
     tcg_gen_mov_tl(cpu_R[CR_STATUS], cpu_R[CR_ESTATUS]);
     tcg_gen_mov_tl(cpu_R[R_PC], cpu_R[R_EA]);
@@ -447,7 +451,9 @@ static void rdctl(DisasContext *dc, uint32_t code, uint32_t flags)
 {
     R_TYPE(instr, code);
 
-    gen_check_supervisor(dc);
+    if (!gen_check_supervisor(dc)) {
+        return;
+    }
 
     if (unlikely(instr.c == R_ZERO)) {
         return;
@@ -474,9 +480,13 @@ static void rdctl(DisasContext *dc, uint32_t code, uint32_t flags)
 /* ctlN <- rA */
 static void wrctl(DisasContext *dc, uint32_t code, uint32_t flags)
 {
-    gen_check_supervisor(dc);
+    if (!gen_check_supervisor(dc)) {
+        return;
+    }
 
-#ifndef CONFIG_USER_ONLY
+#ifdef CONFIG_USER_ONLY
+    g_assert_not_reached();
+#else
     R_TYPE(instr, code);
     TCGv v = load_gpr(dc, instr.a);