Re: [Qemu-devel] [PATCH] RISC-V: fix single stepping over ret and other branching instructions

[Fabien Chouteau]

Thanks Richard,

I sent a version 2.

On 22/03/2019 16:24, Richard Henderson wrote:
> On 3/22/19 4:22 AM, Fabien Chouteau wrote:
>> +/* Wrapper around tcg_gen_exit_tb that handles single stepping */
>> +static void exit_tb(DisasContext *ctx, TranslationBlock *tb, unsigned idx)
>> +{
>> +    if (ctx->base.singlestep_enabled) {
>> +        gen_exception_debug();
>> +    } else {
>> +        tcg_gen_exit_tb(tb, idx);
>> +    }
>> +}
> 
> You should remove the TB and idx parameters here and pass NULL, 0 to
> tcg_gen_exit_tb.
> 
>> @@ -138,14 +158,10 @@ static void gen_goto_tb(DisasContext *ctx, int n, 
>> target_ulong dest)
>>          /* chaining is only allowed when the jump is to the same page */
>>          tcg_gen_goto_tb(n);
>>          tcg_gen_movi_tl(cpu_pc, dest);
>> -        tcg_gen_exit_tb(ctx->base.tb, n);
>> +        exit_tb(ctx, ctx->base.tb, n);
> 
> Because this is the only non-zero use, and it is already protected by
> use_goto_tb, which includes the single-step check.
> 
> Because goto_tb(n) must be paired with exit_tb(tb, n), and vice-versa.
> 
> 
> r~
>