Re: [PATCH 09/10] target/ppc: Simplify syscall exception handlers

[Nicholas Piggin]

On Mon Jun 12, 2023 at 8:42 AM 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.
>
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> ---
>  target/ppc/excp_helper.c | 26 ++++++++++----------------
>  1 file changed, 10 insertions(+), 16 deletions(-)
>
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 4f6a6dfb19..089417894e 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -738,26 +738,23 @@ static void powerpc_excp_7xx(PowerPCCPU *cpu, int excp)
>          break;
>      case POWERPC_EXCP_SYSCALL:   /* System call exception                    
> */
>      {
> -        int lev = env->error_code;
> +        PowerPCCPU *cpu = env_archcpu(env);

I prefer to keep lev. Makes sense to combine the tests though
I suppose. Although with powernv it's not really clear that we
want to dump_syscall. dump_hcall is probably better (powernv
could support a non-PAPR hypervisor with different hcall
semantics, but also it could support an OS with different
syscall semantics too). I guess that could be changed back
when necessary though.

Thanks,
Nick

>  
> -        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(env->error_code == 1 && cpu->vhyp)) {
>              PPCVirtualHypervisorClass *vhc =
>                  PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp);
> +            dump_hcall(env);
>              vhc->hypercall(cpu->vhyp, cpu);
>              return;
> +        } else {
> +            dump_syscall(env);
>          }
> -
>          break;
>      }
>      case POWERPC_EXCP_FPU:       /* Floating-point unavailable exception     
> */
> @@ -882,26 +879,23 @@ static void powerpc_excp_74xx(PowerPCCPU *cpu, int excp)
>          break;
>      case POWERPC_EXCP_SYSCALL:   /* System call exception                    
> */
>      {
> -        int lev = env->error_code;
> +        PowerPCCPU *cpu = env_archcpu(env);
>  
> -        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 74xx CPUs, so although the 74xx don't have
>           * HV mode, we need to keep hypercall support.
>           */
> -        if (lev == 1 && cpu->vhyp) {
> +        if (unlikely(env->error_code == 1 && cpu->vhyp)) {
>              PPCVirtualHypervisorClass *vhc =
>                  PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp);
> +            dump_hcall(env);
>              vhc->hypercall(cpu->vhyp, cpu);
>              return;
> +        } else {
> +            dump_syscall(env);
>          }
> -
>          break;
>      }
>      case POWERPC_EXCP_FPU:       /* Floating-point unavailable exception     
> */
> -- 
> 2.30.9