filter: add XOR operation

Add XOR instruction fo BPF machine. Needed for computing packet hashes.
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/filter.h

@@ -126,7 +126,8 @@ struct sock_fprog {	/* Required for SO_ATTACH_FILTER. */
 #define SKF_AD_HATYPE	28
 #define SKF_AD_RXHASH	32
 #define SKF_AD_CPU	36
-#define SKF_AD_MAX	40
+#define SKF_AD_ALU_XOR_X	40
+#define SKF_AD_MAX	44
 #define SKF_NET_OFF   (-0x100000)
 #define SKF_LL_OFF    (-0x200000)
 
@@ -231,6 +232,7 @@ enum {
 	BPF_S_ANC_HATYPE,
 	BPF_S_ANC_RXHASH,
 	BPF_S_ANC_CPU,
+	BPF_S_ANC_ALU_XOR_X,
 };
 
 #endif /* __KERNEL__ */

net/core/filter.c

@@ -315,6 +315,9 @@ unsigned int sk_run_filter(const struct sk_buff *skb,
 		case BPF_S_ANC_CPU:
 			A = raw_smp_processor_id();
 			continue;
+		case BPF_S_ANC_ALU_XOR_X:
+			A ^= X;
+			continue;
 		case BPF_S_ANC_NLATTR: {
 			struct nlattr *nla;
 
@@ -559,6 +562,7 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
 			ANCILLARY(HATYPE);
 			ANCILLARY(RXHASH);
 			ANCILLARY(CPU);
+			ANCILLARY(ALU_XOR_X);
 			}
 		}
 		ftest->code = code;