MIPS: BPF: Use unsigned access for unsigned SKB fields.

The SKB vlan_tci and queue_mapping fields are unsigned, don't sign
extend these in the BPF JIT.  In the vlan_tci case, the value gets
masked so the change is not needed for correctness, but do it anyway
for agreement with the types defined in struct sk_buff.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Steven J. Hill <steven.hill@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15746/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/net/bpf_jit.c

@@ -1156,7 +1156,7 @@ jmp_cmp:
 			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
 						  vlan_tci) != 2);
 			off = offsetof(struct sk_buff, vlan_tci);
-			emit_half_load(r_s0, r_skb, off, ctx);
+			emit_half_load_unsigned(r_s0, r_skb, off, ctx);
 			if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) {
 				emit_andi(r_A, r_s0, (u16)~VLAN_TAG_PRESENT, ctx);
 			} else {
@@ -1183,7 +1183,7 @@ jmp_cmp:
 			BUILD_BUG_ON(offsetof(struct sk_buff,
 					      queue_mapping) > 0xff);
 			off = offsetof(struct sk_buff, queue_mapping);
-			emit_half_load(r_A, r_skb, off, ctx);
+			emit_half_load_unsigned(r_A, r_skb, off, ctx);
 			break;
 		default:
 			pr_debug("%s: Unhandled opcode: 0x%02x\n", __FILE__,