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

[gaosong]

Hi Richard,

On 2022/6/10 上午2:42, Richard Henderson wrote:

> >   void
> >         helper_asrtle_d(CPULoongArchState *env, target_ulong rj,
> >         target_ulong rk)
> >         
> >           {
> >         
> >               if (rj > rk) {
> >         
> >         +#ifdef CONFIG_USER_ONLY
> >         
> >         +        cpu_loop_exit_sigsegv(env_cpu(env), GETPC(),
> >         
> >         +                              MMU_DATA_LOAD, true, GETPC());
> >         
> >         +#else
> >         
> >                   do_raise_exception(env, EXCCODE_ADEM, GETPC());
> >         
> >         +#endif
> >         
> >       
>       
>       This change is wrong.  First, the kernel's do_ade raises SIGBUS. 
>       Second, GETPC() is a host address, not a guest address.  Third,
>       this highlights the fact that the existing system code is wrong,
>       and should be setting badvaddr.
>       
>       
>       You need to
>       
>       (1) set badvaddr here, and then
>       
>       (2) handle EXCCODE_ADEM in linux-user/loongarch/cpu_loop.c to
>       force_fix_fault(TARGET_SIGBUS, TARGET_BUS_ADRERR,
>       env->badvaddr).
>

badvaddr is env->pc or base->pc_next?   and we just raise exception on use-mode,

like this

  void helper_asrtle_d(CPULoongArchState *env, target_ulong rj, target_ulong rk)
  {
      if (rj > rk) {

         env->badvaddr = env->pc;

#ifdef CONFIG_USER_ONLY
          do_raise_exception(env, EXCCODE_ADEM, GETPC());
#endif

      }

}

cpu_loop.c

        case EXCCODE_ADEM:
            force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRERR, env->badvaddr);
            break;

    Thanks. 
    Song Gao