Re: [PATCH v15 8/9] target/loongarch: Adjust functions and structure to support user-mode

[gaosong]

On 2022/6/12 上午12:06, Richard Henderson wrote:

> > void
> >         helper_asrtle_d(CPULoongArchState *env,  target_ulong rj,
> >         target_ulong  rk)
> >         
> >         {
> >         
> >               if (rj > rk) {
> >         
> >                  env->badvaddr = env->pc;
> >         
> >                  do_raise_exception(env, EXCCODE_BCE, 
> >         env->badvaddr);
> >         
> >               }
> >         
> >         }
> >         
> >       
>       
>       Well, not quite.  The value of env->pc is not current; it is
>       too expensive to update all of the time.  We need to recover that
>       value by using TCG unwinding, e.g.:
>       
>       
>           if (rj > rk) {
>       
>               cpu_restore_state(env_cpu(env), GETPC(), true);
>       
>               env->badvaddr = env->pc;
>       
>       
>       However,
>       
>       
>               do_raise_exception(env, EXCCODE_ADEM, GETPC());
>       
>       
>       expects to do it's own cpu_restore_state via
>       cpu_loop_exit_restore(), and we should not do that twice.
>       
>       
>       Therefore, since the value of badvaddr is something that we can
>       more easily recover later than earlier, we should move the setting
>       of badvaddr for ADEM to loongarch_cpu_do_interrupt():
>       
>       
>           case EXCCODE_ADEM:
>       
>       
>               env->badvaddr = env->pc;
>       
>               cause = cs->exception_index;
>       
>               break;
>       
>       
>       It is probably worthwhile to check how many other exceptions
>       should be having the same effect.
>       
>       
>     
    Thank you for your advice.
    like this:

 void helper_asrtle_d(CPULoongArchState *env, target_ulong rj, target_ulong rk)
 {
+    CPUState *cs = env_cpu(env);
+
     if (rj > rk) {
-        env->badaddr = env->pc;
-        do_raise_exception(env, EXCCODE_BCE, env->badaddr);
+        cpu_restore_state(cs, GETPC(), true);
+        cs->exception_index = EXCCODE_BCE;
+        cpu_loop_exit(cs);
     }
 }

cpu.c

     case EXCCODE_ADEM:
+    case EXCCODE_BCE:
     case EXCCODE_SYS:
     case EXCCODE_BRK:
+    case EXCCODE_INE:
+    case EXCCODE_IPE:
+    case EXCCODE_FPE:
+        env->badvaddr = env->pc;
+        QEMU_FALLTHROUGH;
     case EXCCODE_PIL:
     case EXCCODE_PIS:
     case EXCCODE_PME:
     case EXCCODE_PNR:
     case EXCCODE_PNX:
     case EXCCODE_PPI:
-    case EXCCODE_INE:
-    case EXCCODE_IPE:
-    case EXCCODE_FPE:
         cause = cs->exception_index;
         break;

    Thanks
    Song Gao