Re: [PATCH v2 25/28] target/ppc/mmu_common.c: Simplify ppc_booke_xlate()

["Nicholas Piggin" <npiggin@gmail.com>]

Will review this if we can get -4 case removed...

Don't know if I'm too keen on doing the fetch branch first
and asymmetric (if vs switch) checking of ret in the fetch
vs data cases. I think with -4 case removed things will
look much nicer.

Thanks,
Nick

On Thu May 2, 2024 at 9:43 AM AEST, BALATON Zoltan wrote:
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> ---
>  target/ppc/mmu_common.c | 147 +++++++++++++++-------------------------
>  1 file changed, 56 insertions(+), 91 deletions(-)
>
> diff --git a/target/ppc/mmu_common.c b/target/ppc/mmu_common.c
> index d61c41d8c9..b76611da80 100644
> --- a/target/ppc/mmu_common.c
> +++ b/target/ppc/mmu_common.c
> @@ -1261,106 +1261,71 @@ static bool ppc_booke_xlate(PowerPCCPU *cpu, vaddr eaddr,
>      }
>  
>      log_cpu_state_mask(CPU_LOG_MMU, cs, 0);
> +    env->error_code = 0;
> +    if (env->mmu_model == POWERPC_MMU_BOOKE206 && ret == -1) {
> +        booke206_update_mas_tlb_miss(env, eaddr, access_type, mmu_idx);
> +    }
>      if (access_type == MMU_INST_FETCH) {
> -        switch (ret) {
> -        case -1:
> +        if (ret == -1) {
>              /* No matches in page tables or TLB */
> -            switch (env->mmu_model) {
> -            case POWERPC_MMU_BOOKE206:
> -                booke206_update_mas_tlb_miss(env, eaddr, access_type, mmu_idx);
> -                /* fall through */
> -            case POWERPC_MMU_BOOKE:
> -                cs->exception_index = POWERPC_EXCP_ITLB;
> -                env->error_code = 0;
> -                env->spr[SPR_BOOKE_DEAR] = eaddr;
> -                env->spr[SPR_BOOKE_ESR] = mmubooke206_esr(mmu_idx, access_type);
> -                break;
> -            default:
> -                g_assert_not_reached();
> -            }
> -            break;
> -        case -2:
> -            /* Access rights violation */
> -            cs->exception_index = POWERPC_EXCP_ISI;
> -            env->error_code = 0;
> -            break;
> -        case -3:
> -            /* No execute protection violation */
> -            cs->exception_index = POWERPC_EXCP_ISI;
> -            env->spr[SPR_BOOKE_ESR] = 0;
> -            env->error_code = 0;
> -            break;
> -        case -4:
> -            /* Direct store exception */
> -            /* No code fetch is allowed in direct-store areas */
> +            cs->exception_index = POWERPC_EXCP_ITLB;
> +            env->spr[SPR_BOOKE_DEAR] = eaddr;
> +            env->spr[SPR_BOOKE_ESR] = mmubooke206_esr(mmu_idx, access_type);
> +        } else {
>              cs->exception_index = POWERPC_EXCP_ISI;
> -            env->error_code = 0;
> -            break;
> -        }
> -    } else {
> -        switch (ret) {
> -        case -1:
> -            /* No matches in page tables or TLB */
> -            switch (env->mmu_model) {
> -            case POWERPC_MMU_BOOKE206:
> -                booke206_update_mas_tlb_miss(env, eaddr, access_type, mmu_idx);
> -                /* fall through */
> -            case POWERPC_MMU_BOOKE:
> -                cs->exception_index = POWERPC_EXCP_DTLB;
> -                env->error_code = 0;
> -                env->spr[SPR_BOOKE_DEAR] = eaddr;
> -                env->spr[SPR_BOOKE_ESR] = mmubooke206_esr(mmu_idx, access_type);
> -                break;
> -            default:
> -                g_assert_not_reached();
> +            if (ret == -3) {
> +                /* No execute protection violation */
> +                env->spr[SPR_BOOKE_ESR] = 0;
>              }
> +        }
> +        return false;
> +    }
> +
> +    switch (ret) {
> +    case -1:
> +        /* No matches in page tables or TLB */
> +        cs->exception_index = POWERPC_EXCP_DTLB;
> +        env->spr[SPR_BOOKE_DEAR] = eaddr;
> +        env->spr[SPR_BOOKE_ESR] = mmubooke206_esr(mmu_idx, access_type);
> +        break;
> +    case -2:
> +        /* Access rights violation */
> +        cs->exception_index = POWERPC_EXCP_DSI;
> +        env->spr[SPR_BOOKE_DEAR] = eaddr;
> +        env->spr[SPR_BOOKE_ESR] = mmubooke206_esr(mmu_idx, access_type);
> +        break;
> +    case -4:
> +        /* Direct store exception */
> +        env->spr[SPR_DAR] = eaddr;
> +        switch (env->access_type) {
> +        case ACCESS_FLOAT:
> +            /* Floating point load/store */
> +            cs->exception_index = POWERPC_EXCP_ALIGN;
> +            env->error_code = POWERPC_EXCP_ALIGN_FP;
>              break;
> -        case -2:
> -            /* Access rights violation */
> +        case ACCESS_RES:
> +            /* lwarx, ldarx or stwcx. */
>              cs->exception_index = POWERPC_EXCP_DSI;
> -            env->error_code = 0;
> -            env->spr[SPR_BOOKE_DEAR] = eaddr;
> -            env->spr[SPR_BOOKE_ESR] = mmubooke206_esr(mmu_idx, access_type);
> +            if (access_type == MMU_DATA_STORE) {
> +                env->spr[SPR_DSISR] = 0x06000000;
> +            } else {
> +                env->spr[SPR_DSISR] = 0x04000000;
> +            }
>              break;
> -        case -4:
> -            /* Direct store exception */
> -            switch (env->access_type) {
> -            case ACCESS_FLOAT:
> -                /* Floating point load/store */
> -                cs->exception_index = POWERPC_EXCP_ALIGN;
> -                env->error_code = POWERPC_EXCP_ALIGN_FP;
> -                env->spr[SPR_DAR] = eaddr;
> -                break;
> -            case ACCESS_RES:
> -                /* lwarx, ldarx or stwcx. */
> -                cs->exception_index = POWERPC_EXCP_DSI;
> -                env->error_code = 0;
> -                env->spr[SPR_DAR] = eaddr;
> -                if (access_type == MMU_DATA_STORE) {
> -                    env->spr[SPR_DSISR] = 0x06000000;
> -                } else {
> -                    env->spr[SPR_DSISR] = 0x04000000;
> -                }
> -                break;
> -            case ACCESS_EXT:
> -                /* eciwx or ecowx */
> -                cs->exception_index = POWERPC_EXCP_DSI;
> -                env->error_code = 0;
> -                env->spr[SPR_DAR] = eaddr;
> -                if (access_type == MMU_DATA_STORE) {
> -                    env->spr[SPR_DSISR] = 0x06100000;
> -                } else {
> -                    env->spr[SPR_DSISR] = 0x04100000;
> -                }
> -                break;
> -            default:
> -                printf("DSI: invalid exception (%d)\n", ret);
> -                cs->exception_index = POWERPC_EXCP_PROGRAM;
> -                env->error_code = POWERPC_EXCP_INVAL | POWERPC_EXCP_INVAL_INVAL;
> -                env->spr[SPR_DAR] = eaddr;
> -                break;
> +        case ACCESS_EXT:
> +            /* eciwx or ecowx */
> +            cs->exception_index = POWERPC_EXCP_DSI;
> +            if (access_type == MMU_DATA_STORE) {
> +                env->spr[SPR_DSISR] = 0x06100000;
> +            } else {
> +                env->spr[SPR_DSISR] = 0x04100000;
>              }
>              break;
> +        default:
> +            printf("DSI: invalid exception (%d)\n", ret);
> +            cs->exception_index = POWERPC_EXCP_PROGRAM;
> +            env->error_code = POWERPC_EXCP_INVAL | POWERPC_EXCP_INVAL_INVAL;
> +            break;
>          }
>      }
>      return false;