Re: [RFC PATCH] target/arm: drop CF_LAST_IO/dc->condjump check

["Cédric Le Goater" <clg@kaod.org>]

On 4/16/21 5:49 PM, Alex Bennée wrote:
> This is a left over erroneous check from the days front-ends handled
> io start/end themselves. Regardless just because IO could be performed
> on the last instruction doesn't obligate the front end to do so.
> 
> This fixes an abort faced by the aspeed execute-in-place support which
> will necessarily trigger this state (even before the one-shot
> CF_LAST_IO fix). The test still seems to hang once it attempts to boot
> the Linux kernel but I suspect this is an unrelated issue with icount
> and the timer handling code.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Cédric Le Goater <clg@kaod.org>


Tested-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C. 


> ---
>  target/arm/translate.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/target/arm/translate.c b/target/arm/translate.c
> index 62b1c2081b..7103da2d7a 100644
> --- a/target/arm/translate.c
> +++ b/target/arm/translate.c
> @@ -9199,11 +9199,6 @@ static void arm_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
>  {
>      DisasContext *dc = container_of(dcbase, DisasContext, base);
>  
> -    if (tb_cflags(dc->base.tb) & CF_LAST_IO && dc->condjmp) {
> -        /* FIXME: This can theoretically happen with self-modifying code. */
> -        cpu_abort(cpu, "IO on conditional branch instruction");
> -    }
> -
>      /* At this stage dc->condjmp will only be set when the skipped
>         instruction was a conditional branch or trap, and the PC has
>         already been written.  */
>