[PATCH] bpf, powerpc: fix jit for seccomp_data access

[Mark Lord]

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;
-- 
Mark Lord
Real-Time Remedies Inc.
mlord at pobox.com