Re: [Qemu-devel] [Qemu-ppc] [V3 PATCH 9/9] target-ppc: Add Store Quadword Conditional

[Alexander Graf <agraf@suse.de>]

On 10.02.2014, at 18:27, Tom Musta <tommusta@gmail.com> wrote:

> This patch adds the Store Quadword Conditionl (stqcx.) instruction
> which is introduced in Power ISA 2.07.
> 
> Signed-off-by: Tom Musta <tommusta@gmail.com>
> ---
> V2: Updated linux-user/main.c to use the newly added reserve_val2.
> 
> V3: Fixed erroneousl val2 check per Alex Graf's review.
> 
> linux-user/main.c      |   18 +++++++++++++++++-
> target-ppc/translate.c |   21 +++++++++++++++++++++
> 2 files changed, 38 insertions(+), 1 deletions(-)
> 
> diff --git a/linux-user/main.c b/linux-user/main.c
> index cabc9e1..0cca37d 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -1490,7 +1490,7 @@ static int do_store_exclusive(CPUPPCState *env)
> {
>     target_ulong addr;
>     target_ulong page_addr;
> -    target_ulong val;
> +    target_ulong val, val2;
>     int flags;
>     int segv = 0;
> 
> @@ -1513,6 +1513,13 @@ static int do_store_exclusive(CPUPPCState *env)
>             case 4: segv = get_user_u32(val, addr); break;
> #if defined(TARGET_PPC64)
>             case 8: segv = get_user_u64(val, addr); break;
> +            case 16: {
> +                segv = get_user_u64(val, addr);
> +                if (!segv) {
> +                    segv = get_user_u64(val2, addr + 8);
> +                }
> +                break;
> +            }
> #endif
>             default: abort();
>             }
> @@ -1524,6 +1531,15 @@ static int do_store_exclusive(CPUPPCState *env)
>                 case 4: segv = put_user_u32(val, addr); break;
> #if defined(TARGET_PPC64)
>                 case 8: segv = put_user_u64(val, addr); break;
> +                case 16: {
> +                    if (val2 == env->reserve_val2) {
> +                        segv = put_user_u64(val, addr);
> +                        if (!segv) {
> +                            segv = put_user_u64(val2, addr + 8);
> +                        }
> +                    }
> +                    break;
> +                }
> #endif
>                 default: abort();
>                 }
> diff --git a/target-ppc/translate.c b/target-ppc/translate.c
> index 77de07a..cf0ebc7 100644
> --- a/target-ppc/translate.c
> +++ b/target-ppc/translate.c
> @@ -3329,6 +3329,20 @@ static void gen_conditional_store(DisasContext *ctx, TCGv EA,
>         gen_qemu_st32(ctx, cpu_gpr[reg], EA);
>     } else if (size == 2) {
>         gen_qemu_st16(ctx, cpu_gpr[reg], EA);
> +#if defined(TARGET_PPC64)
> +    } else if (size == 16) {
> +        TCGv gpr1, gpr2;
> +        if (unlikely(ctx->le_mode)) {
> +            gpr1 = cpu_gpr[reg+1];
> +            gpr2 = cpu_gpr[reg];
> +        } else {
> +            gpr1 = cpu_gpr[reg];
> +            gpr2 = cpu_gpr[reg+1];
> +        }
> +        gen_qemu_st64(ctx, gpr1, EA);
> +        gen_addr_add(ctx, EA, EA, 8);

Please send a follow-up patch on top of this one that creates a temporary in this case for EA+8. It's pretty counterintuitive to have an input variable come out with a different value out of a function.


Alex