[v6,5/9] target/ppc: Simplify syscall exception handlers

After previous changes the hypercall handling in 7xx and 74xx
exception handlers can be folded into one if statement to simpilfy
this code. Also add "unlikely" to mark the less freqiently used branch
for the compiler.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
---
 target/ppc/excp_helper.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

On 22/2/24 12:33, BALATON Zoltan wrote:
> After previous changes the hypercall handling in 7xx and 74xx
> exception handlers can be folded into one if statement to simpilfy

"simplify"

> this code. Also add "unlikely" to mark the less freqiently used branch

"frequently"

> for the compiler.
> 
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> ---
>   target/ppc/excp_helper.c | 24 ++++++++----------------
>   1 file changed, 8 insertions(+), 16 deletions(-)

On Thu, 22 Feb 2024, Philippe Mathieu-Daudé wrote:
> On 22/2/24 12:33, BALATON Zoltan wrote:
>> After previous changes the hypercall handling in 7xx and 74xx
>> exception handlers can be folded into one if statement to simpilfy
>
> "simplify"
>
>> this code. Also add "unlikely" to mark the less freqiently used branch
>
> "frequently"

Could these be fixed up when merging please? I'd not resend again unless 
there's some other things need fixing.

Regards,
BALATON Zoltan

>> for the compiler.
>> 
>> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
>> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
>> ---
>>   target/ppc/excp_helper.c | 24 ++++++++----------------
>>   1 file changed, 8 insertions(+), 16 deletions(-)
>
>
>

On Thu Feb 22, 2024 at 9:33 PM AEST, BALATON Zoltan wrote:
> After previous changes the hypercall handling in 7xx and 74xx
> exception handlers can be folded into one if statement to simpilfy
> this code. Also add "unlikely" to mark the less freqiently used branch
> for the compiler.
>
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> ---
>  target/ppc/excp_helper.c | 24 ++++++++----------------
>  1 file changed, 8 insertions(+), 16 deletions(-)
>
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 411d67376c..035a9fd968 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -762,26 +762,22 @@ static void powerpc_excp_7xx(PowerPCCPU *cpu, int excp)
>      case POWERPC_EXCP_SYSCALL:   /* System call exception                    */
>      {
>          int lev = env->error_code;
> -
> -        if (lev == 1 && cpu->vhyp) {
> -            dump_hcall(env);
> -        } else {
> -            dump_syscall(env);
> -        }
>          /*
>           * The Virtual Open Firmware (VOF) relies on the 'sc 1'
>           * instruction to communicate with QEMU. The pegasos2 machine
>           * uses VOF and the 7xx CPUs, so although the 7xx don't have
>           * HV mode, we need to keep hypercall support.
>           */
> -        if (lev == 1 && cpu->vhyp) {
> +        if (unlikely(lev == 1 && cpu->vhyp)) {
>              PPCVirtualHypervisorClass *vhc =
>                  PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp);
> +            dump_hcall(env);
>              vhc->hypercall(cpu->vhyp, cpu);
>              powerpc_reset_excp_state(cpu);
>              return;
> +        } else {
> +            dump_syscall(env);
>          }
> -
>          break;

You could avoid the else statement for these because the
hcall branch returns.

Actually books could be changed similarly too, I think dump_hcall can be
done in the books_vhyp_handles_hcall() branch. But you don't need to
change that in your patch since it's behaviour change.

Thanks,
Nick

On Thu Feb 22, 2024 at 10:20 PM AEST, BALATON Zoltan wrote:
> On Thu, 22 Feb 2024, Philippe Mathieu-Daudé wrote:
> > On 22/2/24 12:33, BALATON Zoltan wrote:
> >> After previous changes the hypercall handling in 7xx and 74xx
> >> exception handlers can be folded into one if statement to simpilfy
> >
> > "simplify"
> >
> >> this code. Also add "unlikely" to mark the less freqiently used branch
> >
> > "frequently"
>
> Could these be fixed up when merging please? I'd not resend again unless 
> there's some other things need fixing.

Main thing was the gen_exception_err code shraing with sc. If you
wouldn't mind resending the series with all fixups. I'll plan to
get another ppc PR in before soft freeze in ~ 2 weeks so and I'll
grab this if possible.

Thanks,
Nick