ARM: net: add support for BPF_ANC | SKF_AD_HATYPE in ARM JIT.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: nschichan

arch/arm/net/bpf_jit_32.c

@@ -857,7 +857,9 @@ static int build_body(struct jit_ctx *ctx)
 			emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
 			break;
 		case BPF_ANC | SKF_AD_IFINDEX:
+		case BPF_ANC | SKF_AD_HATYPE:
 			/* A = skb->dev->ifindex */
+			/* A = skb->dev->type */
 			ctx->seen |= SEEN_SKB;
 			off = offsetof(struct sk_buff, dev);
 			emit(ARM_LDR_I(r_scratch, r_skb, off), ctx);
@@ -867,8 +869,24 @@ static int build_body(struct jit_ctx *ctx)
 
 			BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
 						  ifindex) != 4);
-			off = offsetof(struct net_device, ifindex);
-			emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
+			BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
+						  type) != 2);
+
+			if (code == (BPF_ANC | SKF_AD_IFINDEX)) {
+				off = offsetof(struct net_device, ifindex);
+				emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
+			} else {
+				/*
+				 * offset of field "type" in "struct
+				 * net_device" is above what can be
+				 * used in the ldrh rd, [rn, #imm]
+				 * instruction, so load the offset in
+				 * a register and use ldrh rd, [rn, rm]
+				 */
+				off = offsetof(struct net_device, type);
+				emit_mov_i(ARM_R3, off, ctx);
+				emit(ARM_LDRH_R(r_A, r_scratch, ARM_R3), ctx);
+			}
 			break;
 		case BPF_ANC | SKF_AD_MARK:
 			ctx->seen |= SEEN_SKB;

arch/arm/net/bpf_jit_32.h

@@ -74,6 +74,7 @@
 #define ARM_INST_LDRB_I		0x05d00000
 #define ARM_INST_LDRB_R		0x07d00000
 #define ARM_INST_LDRH_I		0x01d000b0
+#define ARM_INST_LDRH_R		0x019000b0
 #define ARM_INST_LDR_I		0x05900000
 
 #define ARM_INST_LDM		0x08900000
@@ -160,6 +161,8 @@
 				 | (rm))
 #define ARM_LDRH_I(rt, rn, off)	(ARM_INST_LDRH_I | (rt) << 12 | (rn) << 16 \
 				 | (((off) & 0xf0) << 4) | ((off) & 0xf))
+#define ARM_LDRH_R(rt, rn, rm)	(ARM_INST_LDRH_R | (rt) << 12 | (rn) << 16 \
+				 | (rm))
 
 #define ARM_LDM(rn, regs)	(ARM_INST_LDM | (rn) << 16 | (regs))