[PATCH net-next 12/12] nfp: bpf: support direct packet access in TC

[Jakub Kicinski]

Add support for direct packet access in TC, note that because
writing the packet will cause the verifier to generate a csum
fixup prologue we won't be able to offload packet writes from
TC, just yet, only the reads will work.

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
Reviewed-by: Simon Horman <simon.hor...@netronome.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/jit.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c 
b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index 139a4ebdc774..23fb11a41cc4 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -1135,12 +1135,25 @@ static int data_ind_ld4(struct nfp_prog *nfp_prog, 
struct nfp_insn_meta *meta)
 static int mem_ldx_skb(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
                       u8 size)
 {
+       swreg dst = reg_both(meta->insn.dst_reg * 2);
+
        switch (meta->insn.off) {
        case offsetof(struct sk_buff, len):
                if (size != FIELD_SIZEOF(struct sk_buff, len))
                        return -EOPNOTSUPP;
-               wrp_mov(nfp_prog,
-                       reg_both(meta->insn.dst_reg * 2), plen_reg(nfp_prog));
+               wrp_mov(nfp_prog, dst, plen_reg(nfp_prog));
+               break;
+       case offsetof(struct sk_buff, data):
+               if (size != sizeof(void *))
+                       return -EOPNOTSUPP;
+               wrp_mov(nfp_prog, dst, pptr_reg(nfp_prog));
+               break;
+       case offsetof(struct sk_buff, cb) +
+            offsetof(struct bpf_skb_data_end, data_end):
+               if (size != sizeof(void *))
+                       return -EOPNOTSUPP;
+               emit_alu(nfp_prog, dst,
+                        plen_reg(nfp_prog), ALU_OP_ADD, pptr_reg(nfp_prog));
                break;
        default:
                return -EOPNOTSUPP;
-- 
2.14.1