bpf, powerpc: fix jit for seccomp_data access

[Michael Ellerman]

On Tue, 2018-02-20 at 19:49:20 UTC, Mark Lord wrote:
> I am using SECCOMP to filter syscalls on a ppc32 platform,
> and noticed that the JIT compiler was failing on the BPF
> even though the interpreter was working fine.
> 
> The issue was that the compiler was missing one of the instructions
> used by SECCOMP, so here is a patch to enable JIT for that instruction.
> 
> Signed-Off-By:  Mark Lord <mlord at pobox.com>
> 
> --- old/arch/powerpc/net/bpf_jit_comp.c 2018-02-16 14:07:01.000000000 -0500
> +++ linux/arch/powerpc/net/bpf_jit_comp.c       2018-02-20 14:41:20.805227494 -0500
> @@ -329,6 +329,9 @@ static int bpf_jit_build_body(struct bpf
>                         BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
>                         PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, len));
>                         break;
> +               case BPF_LDX | BPF_W | BPF_ABS: /* A = *((u32 *)(seccomp_data + K)); */
> +                       PPC_LWZ_OFFS(r_A, r_skb, K);
> +                       break;
>                 case BPF_LDX | BPF_W | BPF_LEN: /* X = skb->len; */
>                         PPC_LWZ_OFFS(r_X, r_skb, offsetof(struct sk_buff, len));
>                         break;

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/083b20907185b076f21c265b30fe5b

cheers