Re: [PATCH v2 08/19] target/ppc: Sign-extend large decrementer to 64-bits

[Cédric Le Goater]

Nick,

On 8/8/23 06:19, Nicholas Piggin wrote:
> When storing a large decrementer value with the most significant
> implemented bit set, it is to be treated as a negative and sign
> extended.
>
> This isn't hit for book3s DEC because of another bug, fixing it
> in the next patch exposes this one and can cause additional
> problems, so fix this first. It can be hit with HDECR and other
> edge triggered types.
>
> Fixes: a8dafa52518 ("target/ppc: Implement large decrementer support for TCG")
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>   hw/ppc/ppc.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> index a397820d9c..fb4784793c 100644
> --- a/hw/ppc/ppc.c
> +++ b/hw/ppc/ppc.c
> @@ -743,7 +743,9 @@ target_ulong cpu_ppc_load_decr(CPUPPCState *env)
>        * to 64 bits, otherwise it is a 32 bit value.
>        */
>       if (env->spr[SPR_LPCR] & LPCR_LD) {
> -        return decr;
> +        PowerPCCPU *cpu = env_archcpu(env);
> +        PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> +        return sextract64(decr, 0, pcc->lrg_decr_bits);
>       }
>       return (uint32_t) decr;
>   }
> @@ -762,7 +764,9 @@ target_ulong cpu_ppc_load_hdecr(CPUPPCState *env)
>        * extended to 64 bits, otherwise it is 32 bits.
>        */
>       if (pcc->lrg_decr_bits > 32) {
> -        return hdecr;
> +        PowerPCCPU *cpu = env_archcpu(env);
> +        PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);

Why are 'cpu' and 'ppc' duplicated ?

Thanks,

C.


> +        return sextract64(hdecr, 0, pcc->lrg_decr_bits);
>       }
>       return (uint32_t) hdecr;
>   }