PPC: bpf_jit_comp: add SKF_AD_PKTTYPE instruction

Add BPF extension SKF_AD_PKTTYPE to ppc JIT to load
skb->pkt_type field.

Before:
[   88.262622] test_bpf: #11 LD_IND_NET 86 97 99 PASS
[   88.265740] test_bpf: #12 LD_PKTTYPE 109 107 PASS

After:
[   80.605964] test_bpf: #11 LD_IND_NET 44 40 39 PASS
[   80.607370] test_bpf: #12 LD_PKTTYPE 9 9 PASS

CC: Alexei Starovoitov<alexei.starovoitov@gmail.com>
CC: Michael Ellerman<mpe@ellerman.id.au>
Cc: Matt Evans <matt@ozlabs.org>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>

v2: Added test rusults
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/powerpc/include/asm/ppc-opcode.h

@@ -204,6 +204,7 @@
 #define PPC_INST_ERATSX_DOT		0x7c000127
 
 /* Misc instructions for BPF compiler */
+#define PPC_INST_LBZ			0x88000000
 #define PPC_INST_LD			0xe8000000
 #define PPC_INST_LHZ			0xa0000000
 #define PPC_INST_LHBRX			0x7c00062c

arch/powerpc/net/bpf_jit.h

@@ -87,6 +87,9 @@ DECLARE_LOAD_FUNC(sk_load_byte_msh);
 #define PPC_STD(r, base, i)	EMIT(PPC_INST_STD | ___PPC_RS(r) |	      \
 				     ___PPC_RA(base) | ((i) & 0xfffc))
 
+
+#define PPC_LBZ(r, base, i)	EMIT(PPC_INST_LBZ | ___PPC_RT(r) |	      \
+				     ___PPC_RA(base) | IMM_L(i))
 #define PPC_LD(r, base, i)	EMIT(PPC_INST_LD | ___PPC_RT(r) |	      \
 				     ___PPC_RA(base) | IMM_L(i))
 #define PPC_LWZ(r, base, i)	EMIT(PPC_INST_LWZ | ___PPC_RT(r) |	      \
@@ -96,6 +99,10 @@ DECLARE_LOAD_FUNC(sk_load_byte_msh);
 #define PPC_LHBRX(r, base, b)	EMIT(PPC_INST_LHBRX | ___PPC_RT(r) |	      \
 				     ___PPC_RA(base) | ___PPC_RB(b))
 /* Convenience helpers for the above with 'far' offsets: */
+#define PPC_LBZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LBZ(r, base, i);   \
+		else {	PPC_ADDIS(r, base, IMM_HA(i));			      \
+			PPC_LBZ(r, r, IMM_L(i)); } } while(0)
+
 #define PPC_LD_OFFS(r, base, i) do { if ((i) < 32768) PPC_LD(r, base, i);     \
 		else {	PPC_ADDIS(r, base, IMM_HA(i));			      \
 			PPC_LD(r, r, IMM_L(i)); } } while(0)

arch/powerpc/net/bpf_jit_comp.c

@@ -407,6 +407,11 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
 			PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
 							  queue_mapping));
 			break;
+		case BPF_ANC | SKF_AD_PKTTYPE:
+			PPC_LBZ_OFFS(r_A, r_skb, PKT_TYPE_OFFSET());
+			PPC_ANDI(r_A, r_A, PKT_TYPE_MAX);
+			PPC_SRWI(r_A, r_A, 5);
+			break;
 		case BPF_ANC | SKF_AD_CPU:
 #ifdef CONFIG_SMP
 			/*