Re: [PATCH v1 2/2] target/microblaze: Improve transaction failure handling

[Luc Michel]

On 8/28/20 1:39 PM, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
>
> When the CPU has exceptions disabled, avoid unwinding CPU
> state and clobbering registers if we're not going to raise
> any exception.
>
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>

Reviewed-by: Luc Michel <luc.michel@greensocs.com>

> ---
>   target/microblaze/op_helper.c | 19 +++++++------------
>   1 file changed, 7 insertions(+), 12 deletions(-)
>
> diff --git a/target/microblaze/op_helper.c b/target/microblaze/op_helper.c
> index 13ac476199..190cd96c6a 100644
> --- a/target/microblaze/op_helper.c
> +++ b/target/microblaze/op_helper.c
> @@ -483,22 +483,17 @@ void mb_cpu_transaction_failed(CPUState *cs, hwaddr 
> physaddr, vaddr addr,
>       cpu = MICROBLAZE_CPU(cs);
>       env = &cpu->env;
>   
> -    cpu_restore_state(cs, retaddr, true);
>       if (!(env->sregs[SR_MSR] & MSR_EE)) {
>           return;
>       }
>   
> -    env->sregs[SR_EAR] = addr;
> -    if (access_type == MMU_INST_FETCH) {
> -        if (cpu->cfg.iopb_bus_exception) {
> -            env->sregs[SR_ESR] = ESR_EC_INSN_BUS;
> -            helper_raise_exception(env, EXCP_HW_EXCP);
> -        }
> -    } else {
> -        if (cpu->cfg.dopb_bus_exception) {
> -            env->sregs[SR_ESR] = ESR_EC_DATA_BUS;
> -            helper_raise_exception(env, EXCP_HW_EXCP);
> -        }
> +    if ((access_type == MMU_INST_FETCH && cpu->cfg.iopb_bus_exception) ||
> +        (access_type != MMU_INST_FETCH && cpu->cfg.dopb_bus_exception)) {
> +        cpu_restore_state(cs, retaddr, true);
> +        env->sregs[SR_ESR] = access_type == MMU_INST_FETCH ?
> +                             ESR_EC_INSN_BUS : ESR_EC_DATA_BUS;
> +        env->sregs[SR_EAR] = addr;
> +        helper_raise_exception(env, EXCP_HW_EXCP);
>       }
>   }
>   #endif