Re: [PATCH 3/4] target/tricore: Honour privilege changes on PSW write

[Richard Henderson]

On 6/14/23 18:59, Bastian Koppelmann wrote:
  void helper_psw_write(CPUTriCoreState *env, uint32_t arg)
  {
+    uint32_t old_priv, new_priv;
+    CPUState *cs;
+
+    old_priv = extract32(env->PSW, 10, 2);
      psw_write(env, arg);
+    new_priv = extract32(env->PSW, 10, 2);
+
+    if (old_priv != new_priv) {
+        cs = env_cpu(env);
+        env->PC = env->PC + 4;
+        cpu_loop_exit(cs);
+    }
  }

I think you should unconditionally end the TB after write to PSW. I think that you should 
not manipulate the PC here, nor use cpu_loop_exit.

You should add

#define DISAS_EXIT         DISAS_TARGET_0
#define DISAS_EXIT_UPDATE  DISAS_TARGET_1

@@ -378,6 +379,7 @@ static inline void gen_mtcr(DisasContext *ctx, TCGv r1,
     if (ctx->priv == TRICORE_PRIV_SM) {
         /* since we're caching PSW make this a special case */
         if (offset == 0xfe04) {
+            gen_save_pc(ctx->base.pc_next);
             gen_helper_psw_write(cpu_env, r1);

Instead set ctx->base.is_jmp = DISAS_EXIT,

and in tricore_tr_tb_stop add

    case DISAS_EXIT_UPDATE:
        gen_save_pc(ctx->base.pc_next);
        /* fall through */
    case DISAS_EXIT:
        tcg_gen_exit_tb(NULL, 0);
        break;

There are a number of places (e.g. rfe), which can then use DISAS_EXIT instead of issuing 
the exit directly.

I'll also say that there are a number of other places using tcg_gen_exit_tb which should 
instead be using tcg_gen_lookup_and_goto_ptr -- all of the indirect branches for instance. 
 I would suggest adding

#define DISAS_JUMP    DISAS_TARGET_2

to handle those, again with the code within tricore_tr_tb_stop.

Finally, does JLI really clobber A[11] before branching to A[a]?
If so, this could use a comment, because it looks like a bug.


r~