net: dsa: qca8k: fix inband mgmt for big-endian systems

The header and the data of the skb for the inband mgmt requires
to be in little-endian. This is problematic for big-endian system
as the mgmt header is written in the cpu byte order.

Fix this by converting each value for the mgmt header and data to
little-endian, and convert to cpu byte order the mgmt header and
data sent by the switch.

Fixes: 5950c7c0 ("net: dsa: qca8k: add support for mgmt read/write in Ethernet packet")
Tested-by: Pawel Dembicki <paweldembicki@gmail.com>
Tested-by: Lech Perczak <lech.perczak@gmail.com>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Lech Perczak <lech.perczak@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/qca/qca8k-8xxx.c

@@ -137,27 +137,42 @@ static void qca8k_rw_reg_ack_handler(struct dsa_switch *ds, struct sk_buff *skb)
 	struct qca8k_mgmt_eth_data *mgmt_eth_data;
 	struct qca8k_priv *priv = ds->priv;
 	struct qca_mgmt_ethhdr *mgmt_ethhdr;
+	u32 command;
 	u8 len, cmd;
+	int i;
 
 	mgmt_ethhdr = (struct qca_mgmt_ethhdr *)skb_mac_header(skb);
 	mgmt_eth_data = &priv->mgmt_eth_data;
 
-	cmd = FIELD_GET(QCA_HDR_MGMT_CMD, mgmt_ethhdr->command);
-	len = FIELD_GET(QCA_HDR_MGMT_LENGTH, mgmt_ethhdr->command);
+	command = get_unaligned_le32(&mgmt_ethhdr->command);
+	cmd = FIELD_GET(QCA_HDR_MGMT_CMD, command);
+	len = FIELD_GET(QCA_HDR_MGMT_LENGTH, command);
 
 	/* Make sure the seq match the requested packet */
-	if (mgmt_ethhdr->seq == mgmt_eth_data->seq)
+	if (get_unaligned_le32(&mgmt_ethhdr->seq) == mgmt_eth_data->seq)
 		mgmt_eth_data->ack = true;
 
 	if (cmd == MDIO_READ) {
-		mgmt_eth_data->data[0] = mgmt_ethhdr->mdio_data;
+		u32 *val = mgmt_eth_data->data;
+
+		*val = get_unaligned_le32(&mgmt_ethhdr->mdio_data);
 
 		/* Get the rest of the 12 byte of data.
 		 * The read/write function will extract the requested data.
 		 */
-		if (len > QCA_HDR_MGMT_DATA1_LEN)
-			memcpy(mgmt_eth_data->data + 1, skb->data,
-			       QCA_HDR_MGMT_DATA2_LEN);
+		if (len > QCA_HDR_MGMT_DATA1_LEN) {
+			__le32 *data2 = (__le32 *)skb->data;
+			int data_len = min_t(int, QCA_HDR_MGMT_DATA2_LEN,
+					     len - QCA_HDR_MGMT_DATA1_LEN);
+
+			val++;
+
+			for (i = sizeof(u32); i <= data_len; i += sizeof(u32)) {
+				*val = get_unaligned_le32(data2);
+				val++;
+				data2++;
+			}
+		}
 	}
 
 	complete(&mgmt_eth_data->rw_done);
@@ -169,8 +184,10 @@ static struct sk_buff *qca8k_alloc_mdio_header(enum mdio_cmd cmd, u32 reg, u32 *
 	struct qca_mgmt_ethhdr *mgmt_ethhdr;
 	unsigned int real_len;
 	struct sk_buff *skb;
-	u32 *data2;
+	__le32 *data2;
+	u32 command;
 	u16 hdr;
+	int i;
 
 	skb = dev_alloc_skb(QCA_HDR_MGMT_PKT_LEN);
 	if (!skb)
@@ -199,20 +216,32 @@ static struct sk_buff *qca8k_alloc_mdio_header(enum mdio_cmd cmd, u32 reg, u32 *
 	hdr |= FIELD_PREP(QCA_HDR_XMIT_DP_BIT, BIT(0));
 	hdr |= FIELD_PREP(QCA_HDR_XMIT_CONTROL, QCA_HDR_XMIT_TYPE_RW_REG);
 
-	mgmt_ethhdr->command = FIELD_PREP(QCA_HDR_MGMT_ADDR, reg);
-	mgmt_ethhdr->command |= FIELD_PREP(QCA_HDR_MGMT_LENGTH, real_len);
-	mgmt_ethhdr->command |= FIELD_PREP(QCA_HDR_MGMT_CMD, cmd);
-	mgmt_ethhdr->command |= FIELD_PREP(QCA_HDR_MGMT_CHECK_CODE,
+	command = FIELD_PREP(QCA_HDR_MGMT_ADDR, reg);
+	command |= FIELD_PREP(QCA_HDR_MGMT_LENGTH, real_len);
+	command |= FIELD_PREP(QCA_HDR_MGMT_CMD, cmd);
+	command |= FIELD_PREP(QCA_HDR_MGMT_CHECK_CODE,
 					   QCA_HDR_MGMT_CHECK_CODE_VAL);
 
+	put_unaligned_le32(command, &mgmt_ethhdr->command);
+
 	if (cmd == MDIO_WRITE)
-		mgmt_ethhdr->mdio_data = *val;
+		put_unaligned_le32(*val, &mgmt_ethhdr->mdio_data);
 
 	mgmt_ethhdr->hdr = htons(hdr);
 
 	data2 = skb_put_zero(skb, QCA_HDR_MGMT_DATA2_LEN + QCA_HDR_MGMT_PADDING_LEN);
-	if (cmd == MDIO_WRITE && len > QCA_HDR_MGMT_DATA1_LEN)
-		memcpy(data2, val + 1, len - QCA_HDR_MGMT_DATA1_LEN);
+	if (cmd == MDIO_WRITE && len > QCA_HDR_MGMT_DATA1_LEN) {
+		int data_len = min_t(int, QCA_HDR_MGMT_DATA2_LEN,
+				     len - QCA_HDR_MGMT_DATA1_LEN);
+
+		val++;
+
+		for (i = sizeof(u32); i <= data_len; i += sizeof(u32)) {
+			put_unaligned_le32(*val, data2);
+			data2++;
+			val++;
+		}
+	}
 
 	return skb;
 }
@@ -220,9 +249,11 @@ static struct sk_buff *qca8k_alloc_mdio_header(enum mdio_cmd cmd, u32 reg, u32 *
 static void qca8k_mdio_header_fill_seq_num(struct sk_buff *skb, u32 seq_num)
 {
 	struct qca_mgmt_ethhdr *mgmt_ethhdr;
+	u32 seq;
 
+	seq = FIELD_PREP(QCA_HDR_MGMT_SEQ_NUM, seq_num);
 	mgmt_ethhdr = (struct qca_mgmt_ethhdr *)skb->data;
-	mgmt_ethhdr->seq = FIELD_PREP(QCA_HDR_MGMT_SEQ_NUM, seq_num);
+	put_unaligned_le32(seq, &mgmt_ethhdr->seq);
 }
 
 static int qca8k_read_eth(struct qca8k_priv *priv, u32 reg, u32 *val, int len)

include/linux/dsa/tag_qca.h

@@ -61,9 +61,9 @@ struct sk_buff;
 
 /* Special struct emulating a Ethernet header */
 struct qca_mgmt_ethhdr {
-	u32 command;		/* command bit 31:0 */
-	u32 seq;		/* seq 63:32 */
-	u32 mdio_data;		/* first 4byte mdio */
+	__le32 command;		/* command bit 31:0 */
+	__le32 seq;		/* seq 63:32 */
+	__le32 mdio_data;		/* first 4byte mdio */
 	__be16 hdr;		/* qca hdr */
 } __packed;