Re: [PATCH v4 09/17] target/ppc: Put dbcr0 single-step bits into hflags

[David Gibson]

On Mon, Mar 15, 2021 at 12:46:07PM -0600, Richard Henderson wrote:
> Because these bits were not in hflags, the code generated
> for single-stepping on BookE was essentially random.
> Recompute hflags when storing to dbcr0.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  target/ppc/helper_regs.c | 20 +++++++++++++++-----
>  target/ppc/misc_helper.c |  3 +++
>  target/ppc/translate.c   | 11 -----------
>  3 files changed, 18 insertions(+), 16 deletions(-)
> 
> diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
> index 0a746bffd7..c735540333 100644
> --- a/target/ppc/helper_regs.c
> +++ b/target/ppc/helper_regs.c
> @@ -107,11 +107,21 @@ void hreg_compute_hflags(CPUPPCState *env)
>          hflags |= le << MSR_LE;
>      }
>  
> -    if (ppc_flags & POWERPC_FLAG_BE) {
> -        msr_mask |= 1 << MSR_BE;
> -    }
> -    if (ppc_flags & POWERPC_FLAG_SE) {
> -        msr_mask |= 1 << MSR_SE;
> +    if (ppc_flags & POWERPC_FLAG_DE) {
> +        target_ulong dbcr0 = env->spr[SPR_BOOKE_DBCR0];
> +        if (dbcr0 & DBCR0_ICMP) {
> +            hflags |= 1 << HFLAGS_SE;
> +        }
> +        if (dbcr0 & DBCR0_BRT) {
> +            hflags |= 1 << HFLAGS_BE;
> +        }
> +    } else {
> +        if (ppc_flags & POWERPC_FLAG_BE) {
> +            msr_mask |= 1 << MSR_BE;
> +        }
> +        if (ppc_flags & POWERPC_FLAG_SE) {
> +            msr_mask |= 1 << MSR_SE;
> +        }
>      }
>  
>      if (msr_is_64bit(env, msr)) {
> diff --git a/target/ppc/misc_helper.c b/target/ppc/misc_helper.c
> index b04b4d7c6e..a5ee1fd63c 100644
> --- a/target/ppc/misc_helper.c
> +++ b/target/ppc/misc_helper.c
> @@ -215,6 +215,9 @@ void helper_store_403_pbr(CPUPPCState *env, uint32_t num, 
> target_ulong value)
>  
>  void helper_store_40x_dbcr0(CPUPPCState *env, target_ulong val)
>  {
> +    /* Bits 26 & 27 affect single-stepping */
> +    hreg_compute_hflags(env);
> +    /* Bits 28 & 29 affect reset or shutdown. */
>      store_40x_dbcr0(env, val);
>  }
>  
> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
> index a85b890bb0..7912495f28 100644
> --- a/target/ppc/translate.c
> +++ b/target/ppc/translate.c
> @@ -7923,17 +7923,6 @@ static void ppc_tr_init_disas_context(DisasContextBase 
> *dcbase, CPUState *cs)
>      if ((hflags >> HFLAGS_BE) & 1) {
>          ctx->singlestep_enabled |= CPU_BRANCH_STEP;
>      }
> -    if ((env->flags & POWERPC_FLAG_DE) && msr_de) {
> -        ctx->singlestep_enabled = 0;
> -        target_ulong dbcr0 = env->spr[SPR_BOOKE_DBCR0];
> -        if (dbcr0 & DBCR0_ICMP) {
> -            ctx->singlestep_enabled |= CPU_SINGLE_STEP;
> -        }
> -        if (dbcr0 & DBCR0_BRT) {
> -            ctx->singlestep_enabled |= CPU_BRANCH_STEP;
> -        }
> -
> -    }
>      if (unlikely(ctx->base.singlestep_enabled)) {
>          ctx->singlestep_enabled |= GDBSTUB_SINGLE_STEP;
>      }

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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