powerpc/bpf/jit: Fix 32-bit JIT for seccomp_data access

[ Upstream commit 083b20907185b076f21c265b30fe5b5f24c03d8c ]

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.

Fixes: eb84bab0fb38 ("ppc: Kconfig: Enable BPF JIT on ppc32")
Signed-off-by: Mark Lord <mlord@pobox.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index f9941b3b5770fca641d2f4a8cf70dbb727fe8b70..f760494ecd66d6fd9eb33a478e0534bd4fc355cd 100644 (file)
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -329,6 +329,9 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
                        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;