[PATCH net-next 6/6] net/bpf: split VLAN_PRESENT bit handling from VLAN_TCI

[Michał Mirosław]

Signed-off-by: Michał Mirosław <mirq-li...@rere.qmqm.pl>
---
v2: save an insn on big-endiands

 net/core/filter.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 1969b3f118c1..7caf0bbbd092 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -188,22 +188,21 @@ static u32 convert_skb_access(int skb_field, int dst_reg, 
int src_reg,
                break;
 
        case SKF_AD_VLAN_TAG:
-       case SKF_AD_VLAN_TAG_PRESENT:
                BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
-               BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
 
                /* dst_reg = *(u16 *) (src_reg + offsetof(vlan_tci)) */
                *insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg,
                                      offsetof(struct sk_buff, vlan_tci));
-               if (skb_field == SKF_AD_VLAN_TAG) {
-                       *insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg,
-                                               ~VLAN_TAG_PRESENT);
-               } else {
-                       /* dst_reg >>= 12 */
-                       *insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, 12);
-                       /* dst_reg &= 1 */
+#ifdef VLAN_TAG_PRESENT
+               *insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, ~VLAN_TAG_PRESENT);
+#endif
+               break;
+       case SKF_AD_VLAN_TAG_PRESENT:
+               *insn++ = BPF_LDX_MEM(BPF_B, dst_reg, src_reg, 
PKT_VLAN_PRESENT_OFFSET());
+               if (PKT_VLAN_PRESENT_BIT)
+                       *insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, 
PKT_VLAN_PRESENT_BIT);
+               if (PKT_VLAN_PRESENT_BIT < 7)
                        *insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, 1);
-               }
                break;
        }
 
-- 
2.11.0