realtek: l3: decode the route dump with the route readers

The debugfs dump kept a record of its own, otto_l3_930x_dump_rec, with a
copy of a route's attributes, and decoded host and prefix rows with its
own copies of the readers' field positions. Split the decoding out of
otto_l3_930x_host_route_read() and otto_l3_930x_route_read() into
decoders that work on a fetched row, use them in the readers, the dump
and the hit clearing, and keep in the record only where an entry sits
and the route it holds.

The dump prints the same. The two debug lines that showed the prefix
reader's intermediate host route, default route and mask bits go with
the decoding they sat in; the prefix length the reader still prints is
what they add up to.

Tested on a Hasivo S1100W-8XGT-SE (RTL9303) with IPv4 host routes and
IPv4 and IPv6 prefix routes, forwarding and trapping. The routes dump,
taken after traffic to the forwarding ones and again after
clear_route_hits, matches main field by field, 28 rows each. Left out of
the comparison are the ULA prefix each boot picks, and the hit bit
outside the three rows that carried the test traffic, which other
traffic can set at any moment. On those three rows the hit bit goes from
1 to 0.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Gennaro Cimmino <gcimmino@rayonra.net>
Link: https://github.com/openwrt/openwrt/pull/25669
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>

target/linux/realtek/files-6.18/drivers/net/dsa/rtl83xx/l3.c

@@ -261,20 +261,16 @@ static void otto_l3_930x_set_egress_mac(struct otto_l3_ctrl *ctrl, u32 idx, u64
 	otto_table_write(RTL9300_TBL_L3_EGR_INTF_MAC, idx, &data);
 }
 
-/* Read a host route entry from the table using its index. Only IPv4 and IPv6 unicast supported */
-static void otto_l3_930x_host_route_read(struct otto_l3_ctrl *ctrl, int idx, struct otto_l3_route *rt)
+/* Decode a host route entry fetched into @data. Returns false unless it is a
+ * valid unicast entry; valid is set for any entry, type for any valid one.
+ */
+static bool otto_l3_930x_host_route_decode(const u32 *data, struct otto_l3_route *rt)
 {
-	/* Only the unicast layout is handled below */
-	u32 data[5];
-	u32 v;
+	u32 v = data[0];
 
-	idx = ((idx / 6) * 8) + (idx % 6);
-
-	otto_table_read(RTL9300_TBL_L3_HOST_ROUTE_IPUC, idx, &data);
-	v = data[0];
 	rt->attr.valid = !!(v & BIT(31));
 	if (!rt->attr.valid)
-		return;
+		return false;
 	rt->attr.type = (v >> 29) & 0x3;
 	switch (rt->attr.type) {
 	case ROUTE_TYPE_IP4UC:
@@ -285,10 +281,8 @@ static void otto_l3_930x_host_route_read(struct otto_l3_ctrl *ctrl, int idx, str
 			      data[1], data[2],
 			      data[3], data[4]);
 		break;
-	case ROUTE_TYPE_IP4MC:
-	case ROUTE_TYPE_IP6MC:
-		dev_warn(ctrl->dev, "route type not supported\n");
-		return;
+	default:
+		return false;
 	}
 
 	rt->attr.hit = !!(v & BIT(20));
@@ -299,6 +293,25 @@ static void otto_l3_930x_host_route_read(struct otto_l3_ctrl *ctrl, int idx, str
 	rt->attr.ttl_check = !!(v & BIT(4));
 	rt->attr.qos_as = !!(v & BIT(3));
 	rt->attr.qos_prio =  v & 0x7;
+
+	return true;
+}
+
+/* Read a host route entry from the table using its index. Only IPv4 and IPv6 unicast supported */
+static void otto_l3_930x_host_route_read(struct otto_l3_ctrl *ctrl, int idx, struct otto_l3_route *rt)
+{
+	/* Only the unicast layout is handled below */
+	u32 data[5];
+
+	idx = ((idx / 6) * 8) + (idx % 6);
+
+	otto_table_read(RTL9300_TBL_L3_HOST_ROUTE_IPUC, idx, &data);
+	if (!otto_l3_930x_host_route_decode(data, rt)) {
+		if (rt->attr.valid)
+			dev_warn(ctrl->dev, "route type not supported\n");
+		return;
+	}
+
 	dev_dbg(ctrl->dev, "index %d is valid: %d\n", idx, rt->attr.valid);
 	dev_dbg(ctrl->dev, "next_hop: %d, hit: %d, action :%d, ttl_dec %d, ttl_check %d, dst_null %d\n",
 		rt->nh.id, rt->attr.hit, rt->attr.action, rt->attr.ttl_dec, rt->attr.ttl_check,
@@ -519,22 +532,18 @@ static int otto_l3_930x_mask6_len(const struct in6_addr *mask)
 	return len;
 }
 
-/* Read a prefix route entry from the L3_PREFIX_ROUTE_IPUC table
- * We currently only support IPv4 and IPv6 unicast route
+/* Decode a prefix route entry fetched into @data. Returns false unless it is
+ * a valid unicast entry; valid is set for any entry, type for any valid one.
  */
-static void otto_l3_930x_route_read(struct otto_l3_ctrl *ctrl, int idx, struct otto_l3_route *rt)
+static bool otto_l3_930x_route_decode(const u32 *data, struct otto_l3_route *rt)
 {
 	bool host_route, default_route;
 	struct in6_addr ip6_m;
-	u32 data[11];
-	u32 v, ip4_m;
+	u32 v;
 
-	dev_dbg(ctrl->dev, "%s\n", __func__);
-
-	otto_table_read(RTL9300_TBL_L3_PREFIX_ROUTE_IPUC, idx, &data);
 	rt->attr.valid = !!(data[0] & BIT(31));
 	if (!rt->attr.valid)
-		return;
+		return false;
 
 	rt->attr.type = (data[0] >> 29) & 0x3;
 
@@ -542,19 +551,16 @@ static void otto_l3_930x_route_read(struct otto_l3_ctrl *ctrl, int idx, struct o
 	host_route = !!(v & BIT(21));
 	default_route = !!(v & BIT(20));
 	rt->prefix_len = -1;
-	dev_dbg(ctrl->dev, "host route %d, default_route %d\n", host_route, default_route);
 
 	switch (rt->attr.type) {
 	case ROUTE_TYPE_IP4UC:
 		rt->dst_ip = data[4];
-		ip4_m = data[9];
-		dev_dbg(ctrl->dev, "Read ip4 mask: %08x\n", ip4_m);
 		if (host_route)
 			rt->prefix_len = 32;
 		else if (default_route)
 			rt->prefix_len = 0;
 		else
-			rt->prefix_len = inet_mask_len(ip4_m);
+			rt->prefix_len = inet_mask_len(data[9]);
 		break;
 	case ROUTE_TYPE_IP6UC:
 		ipv6_addr_set(&rt->dst_ip6,
@@ -570,10 +576,8 @@ static void otto_l3_930x_route_read(struct otto_l3_ctrl *ctrl, int idx, struct o
 		else
 			rt->prefix_len = otto_l3_930x_mask6_len(&ip6_m);
 		break;
-	case ROUTE_TYPE_IP4MC:
-	case ROUTE_TYPE_IP6MC:
-		dev_warn(ctrl->dev, "route type not supported\n");
-		return;
+	default:
+		return false;
 	}
 
 	rt->attr.hit = !!(v & BIT(22));
@@ -584,6 +588,26 @@ static void otto_l3_930x_route_read(struct otto_l3_ctrl *ctrl, int idx, struct o
 	rt->attr.dst_null = !!(v & BIT(4));
 	rt->attr.qos_as = !!(v & BIT(3));
 	rt->attr.qos_prio =  v & 0x7;
+
+	return true;
+}
+
+/* Read a prefix route entry from the L3_PREFIX_ROUTE_IPUC table
+ * We currently only support IPv4 and IPv6 unicast route
+ */
+static void otto_l3_930x_route_read(struct otto_l3_ctrl *ctrl, int idx, struct otto_l3_route *rt)
+{
+	u32 data[11];
+
+	dev_dbg(ctrl->dev, "%s\n", __func__);
+
+	otto_table_read(RTL9300_TBL_L3_PREFIX_ROUTE_IPUC, idx, &data);
+	if (!otto_l3_930x_route_decode(data, rt)) {
+		if (rt->attr.valid)
+			dev_warn(ctrl->dev, "route type not supported\n");
+		return;
+	}
+
 	dev_dbg(ctrl->dev, "index %d is valid: %d\n", idx, rt->attr.valid);
 	dev_dbg(ctrl->dev, "next_hop: %d, hit: %d, action :%d, ttl_dec %d, ttl_check %d, dst_null %d\n",
 		rt->nh.id, rt->attr.hit, rt->attr.action,
@@ -2990,9 +3014,8 @@ static int otto_l3_netevent_notifier(struct notifier_block *this, unsigned long
  * as every other L3 table, so only one of the two is ever held at a time
  * (otto_table_acquire() takes a mutex per register, not per table).
  *
- * Field positions below are taken from otto_l3_930x_host_route_read()/_write()
- * and otto_l3_930x_route_read()/_write() further up in this file, which are
- * mutually consistent.
+ * Rows are decoded by otto_l3_930x_host_route_decode() and
+ * otto_l3_930x_route_decode(), the decoders the route readers use.
  */
 
 static const char * const otto_l3_930x_dump_type_name[4] = {
@@ -3000,7 +3023,7 @@ static const char * const otto_l3_930x_dump_type_name[4] = {
 };
 
 /* Indexed by ROUTE_ACT_*; multicast entries never reach this, so it is only
- * ever indexed with a value produced by the unicast decode below.
+ * ever indexed with a value produced by the unicast decoders.
  */
 static const char * const otto_l3_930x_dump_action_name[4] = {
 	[ROUTE_ACT_FORWARD]  = "fwd",
@@ -3019,30 +3042,19 @@ static const char * const otto_l3_930x_dump_action_name[4] = {
  */
 static const u8 otto_l3_930x_prefix_widths[] = { 1, 2, V6_PREFIX_ROWS, 8 };
 
-/* One valid entry, decoded and ready to print. Multicast entries (type 1 and
- * 3) only carry what word 0 says (valid, type, hence width): no field
- * position beyond that is in this driver or in the GPL SDK excerpts it was
- * written against, so decoded stays false and the dump prints '-' for the
- * rest.
+/* One valid entry, where it sits and the route it holds. Multicast entries
+ * (type 1 and 3) only carry what word 0 says (valid, type, hence width): no
+ * field position beyond that is in this driver or in the GPL SDK excerpts it
+ * was written against, so decoded stays false and the dump prints '-' for
+ * the rest.
  */
 struct otto_l3_930x_dump_rec {
 	bool is_prefix;
 	bool decoded;
 	u32 addr;
 	u32 idx;
-	u8 type;
 	u8 width;
-	bool hit;
-	bool dst_null;
-	u8 action;
-	u16 nh_id;
-	bool ttl_dec;
-	bool ttl_check;
-	bool qos_as;
-	u8 qos_prio;
-	int prefix_len;
-	u32 ip4;
-	struct in6_addr ip6;
+	struct otto_l3_route rt;
 };
 
 /* Decode a host route row already fetched into @data (words 0-4 of the
@@ -3052,87 +3064,35 @@ struct otto_l3_930x_dump_rec {
 static bool otto_l3_930x_dump_decode_host(const u32 *data, u32 addr,
 					  struct otto_l3_930x_dump_rec *rec)
 {
-	u32 v = data[0];
-
-	if (!(v & BIT(31)))
+	memset(rec, 0, sizeof(*rec));
+	rec->decoded = otto_l3_930x_host_route_decode(data, &rec->rt);
+	if (!rec->rt.attr.valid)
 		return false;
 
-	memset(rec, 0, sizeof(*rec));
 	rec->addr = addr;
 	rec->idx = (addr / 8) * 6 + (addr % 8);
-	rec->type = (v >> 29) & 0x3;
-	rec->width = otto_l3_930x_slot_widths[rec->type];
-
-	if (rec->type != 0 && rec->type != 2)
-		return true; /* multicast: type/width only */
-
-	rec->decoded = true;
-	rec->hit = !!(v & BIT(20));
-	rec->dst_null = !!(v & BIT(19));
-	rec->action = (v >> 17) & 0x3;
-	rec->nh_id = (v >> 6) & 0x7ff;
-	rec->ttl_dec = !!(v & BIT(5));
-	rec->ttl_check = !!(v & BIT(4));
-	rec->qos_as = !!(v & BIT(3));
-	rec->qos_prio = v & 0x7;
-
-	if (rec->type == 0) {
-		rec->ip4 = data[4];
-		rec->prefix_len = 32;
-	} else {
-		ipv6_addr_set(&rec->ip6, data[1], data[2], data[3], data[4]);
-		rec->prefix_len = 128;
-	}
+	rec->width = otto_l3_930x_slot_widths[rec->rt.attr.type];
+	if (rec->decoded)
+		rec->rt.prefix_len = rec->rt.attr.type == ROUTE_TYPE_IP4UC ? 32 : 128;
 
 	return true;
 }
 
 /* Decode a prefix route row already fetched into @data (words 0-10 of the
- * RTL9300_TBL_L3_PREFIX_ROUTE_IPMC layout). Field positions match
- * otto_l3_930x_route_read() above exactly. Returns false if not valid.
+ * RTL9300_TBL_L3_PREFIX_ROUTE_IPMC layout). Returns false if not valid.
  */
 static bool otto_l3_930x_dump_decode_prefix(const u32 *data, u32 addr,
 					    struct otto_l3_930x_dump_rec *rec)
 {
-	bool host_route, default_route;
-	struct in6_addr ip6_m;
-	u32 v;
-
-	if (!(data[0] & BIT(31)))
+	memset(rec, 0, sizeof(*rec));
+	rec->decoded = otto_l3_930x_route_decode(data, &rec->rt);
+	if (!rec->rt.attr.valid)
 		return false;
 
-	memset(rec, 0, sizeof(*rec));
 	rec->is_prefix = true;
 	rec->addr = addr;
 	rec->idx = addr;
-	rec->type = (data[0] >> 29) & 0x3;
-	rec->width = otto_l3_930x_prefix_widths[rec->type];
-
-	if (rec->type != 0 && rec->type != 2)
-		return true; /* multicast: type/width only */
-
-	rec->decoded = true;
-	v = data[10];
-	host_route = !!(v & BIT(21));
-	default_route = !!(v & BIT(20));
-	rec->hit = !!(v & BIT(22));
-	rec->action = (v >> 18) & 0x3;
-	rec->nh_id = (v >> 7) & 0x7ff;
-	rec->ttl_dec = !!(v & BIT(6));
-	rec->ttl_check = !!(v & BIT(5));
-	rec->dst_null = !!(v & BIT(4));
-	rec->qos_as = !!(v & BIT(3));
-	rec->qos_prio = v & 0x7;
-
-	if (rec->type == 0) {
-		rec->ip4 = data[4];
-		rec->prefix_len = host_route ? 32 : default_route ? 0 : inet_mask_len(data[9]);
-	} else {
-		ipv6_addr_set(&rec->ip6, data[1], data[2], data[3], data[4]);
-		ipv6_addr_set(&ip6_m, data[6], data[7], data[8], data[9]);
-		rec->prefix_len = host_route ? 128 : default_route ? 0 :
-			otto_l3_930x_mask6_len(&ip6_m);
-	}
+	rec->width = otto_l3_930x_prefix_widths[rec->rt.attr.type];
 
 	return true;
 }
@@ -3160,24 +3120,27 @@ static void otto_l3_930x_dump_print(struct seq_file *m, const struct otto_l3_930
 	}
 
 	if (r->decoded) {
-		snprintf(hit, sizeof(hit), "%d", r->hit);
-		snprintf(action, sizeof(action), "%s", otto_l3_930x_dump_action_name[r->action]);
-		snprintf(nh_id, sizeof(nh_id), "%u", r->nh_id);
-		snprintf(dst_null, sizeof(dst_null), "%d", r->dst_null);
-		snprintf(ttl, sizeof(ttl), "%s",
-			 otto_l3_930x_dump_ttl_label(r->ttl_dec, r->ttl_check));
-		if (r->qos_as)
-			snprintf(qos, sizeof(qos), "%u", r->qos_prio);
+		const struct otto_l3_route *rt = &r->rt;
 
-		if (r->type == 2)
-			snprintf(dest, sizeof(dest), "%pI6c/%d", &r->ip6, r->prefix_len);
+		snprintf(hit, sizeof(hit), "%d", rt->attr.hit);
+		snprintf(action, sizeof(action), "%s",
+			 otto_l3_930x_dump_action_name[rt->attr.action]);
+		snprintf(nh_id, sizeof(nh_id), "%u", rt->nh.id);
+		snprintf(dst_null, sizeof(dst_null), "%d", rt->attr.dst_null);
+		snprintf(ttl, sizeof(ttl), "%s",
+			 otto_l3_930x_dump_ttl_label(rt->attr.ttl_dec, rt->attr.ttl_check));
+		if (rt->attr.qos_as)
+			snprintf(qos, sizeof(qos), "%u", rt->attr.qos_prio);
+
+		if (rt->attr.type == ROUTE_TYPE_IP6UC)
+			snprintf(dest, sizeof(dest), "%pI6c/%d", &rt->dst_ip6, rt->prefix_len);
 		else
-			snprintf(dest, sizeof(dest), "%pI4/%d", &r->ip4, r->prefix_len);
+			snprintf(dest, sizeof(dest), "%pI4/%d", &rt->dst_ip, rt->prefix_len);
 	}
 
 	seq_printf(m, "%-7s%5u 0x%04x %4s %4s %5u 1 %-6s%4s %-48s %-7s%5s %4s %-8s %s\n",
 		   r->is_prefix ? "prefix" : "host", r->idx, r->addr, hash, slot, r->width,
-		   otto_l3_930x_dump_type_name[r->type], hit, dest, action, nh_id, dst_null,
+		   otto_l3_930x_dump_type_name[r->rt.attr.type], hit, dest, action, nh_id, dst_null,
 		   ttl, qos);
 }
 
@@ -3405,7 +3368,7 @@ static int otto_l3_930x_clear_hit_host(unsigned int *cleared, unsigned int *skip
 
 		if (!rec.decoded) {
 			(*skipped_mc)++;
-		} else if (rec.hit) {
+		} else if (rec.rt.attr.hit) {
 			data[0] &= ~BIT(20);
 			__otto_table_write(handle, addr, &data);
 			(*cleared)++;
@@ -3445,7 +3408,7 @@ static int otto_l3_930x_clear_hit_prefix(unsigned int *cleared, unsigned int *sk
 
 		if (!rec.decoded) {
 			(*skipped_mc)++;
-		} else if (rec.hit) {
+		} else if (rec.rt.attr.hit) {
 			data[10] &= ~BIT(22);
 			__otto_table_write(handle, addr, &data);
 			(*cleared)++;