Add support for packet-sniffing tracers to cxgbe(4). This works with

all T4 and T5 based cards and is useful for analyzing TSO, LRO, TOE, and
for general purpose monitoring without tapping any cxgbe or cxl ifnet
directly.

Tracers on the T4/T5 chips provide access to Ethernet frames exactly as
they were received from or transmitted on the wire.  On transmit, a
tracer will capture a frame after TSO segmentation, hw VLAN tag
insertion, hw L3 & L4 checksum insertion, etc.  It will also capture
frames generated by the TCP offload engine (TOE traffic is normally
invisible to the kernel).  On receive, a tracer will capture a frame
before hw VLAN extraction, runt filtering, other badness filtering,
before the steering/drop/L2-rewrite filters or the TOE have had a go at
it, and of course before sw LRO in the driver.

There are 4 tracers on a chip.  A tracer can trace only in one direction
(tx or rx).  For now cxgbetool will set up tracers to capture the first
128B of every transmitted or received frame on a given port.  This is a
small subset of what the hardware can do.  A pseudo ifnet with the same
name as the nexus driver (t4nex0 or t5nex0) will be created for tracing.
The data delivered to this ifnet is an additional copy made inside the
chip.  Normal delivery to cxgbe<n> or cxl<n> will be made as usual.

/* watch cxl0, which is the first port hanging off t5nex0. */
# cxgbetool t5nex0 tracer 0 tx0  (watch what cxl0 is transmitting)
# cxgbetool t5nex0 tracer 1 rx0  (watch what cxl0 is receiving)
# cxgbetool t5nex0 tracer list
# tcpdump -i t5nex0   <== all that cxl0 sees and puts on the wire

If you were doing TSO, a tcpdump on cxl0 may have shown you ~64K
"frames" with no L3/L4 checksum but this will show you the frames that
were actually transmitted.

/* all done */
# cxgbetool t5nex0 tracer 0 disable
# cxgbetool t5nex0 tracer 1 disable
# cxgbetool t5nex0 tracer list
# ifconfig t5nex0 destroy

1 files changed, 202 insertions, 0 deletions

diff --git a/tools/tools/cxgbetool/cxgbetool.c b/tools/tools/cxgbetool/cxgbetool.c
index a97cf1f..44c4b2d 100644
--- a/tools/tools/cxgbetool/cxgbetool.c
+++ b/tools/tools/cxgbetool/cxgbetool.c
@@ -98,6 +98,9 @@ usage(FILE *fp)
 	    "\tregdump [<module>] ...              dump registers\n"
 	    "\tstdio                               interactive mode\n"
 	    "\ttcb <tid>                           read TCB\n"
+	    "\ttracer <idx> tx<n>|rx<n>            set and enable a tracer)\n"
+	    "\ttracer <idx> disable|enable         disable or enable a tracer\n"
+	    "\ttracer list                         list all tracers\n"
 	    );
 }
 
@@ -1658,6 +1661,203 @@ clearstats(int argc, const char *argv[])
 }
 
 static int
+show_tracers(void)
+{
+	struct t4_tracer t;
+	char *s;
+	int rc, port_idx, i;
+	long long val;
+
+	/* Magic values: MPS_TRC_CFG = 0x9800. MPS_TRC_CFG[1:1] = TrcEn */
+	rc = read_reg(0x9800, 4, &val);
+	if (rc != 0)
+		return (rc);
+	printf("tracing is %s\n", val & 2 ? "ENABLED" : "DISABLED");
+
+	t.idx = 0;
+	for (t.idx = 0; ; t.idx++) {
+		rc = doit(CHELSIO_T4_GET_TRACER, &t);
+		if (rc != 0 || t.idx == 0xff)
+			break;
+
+		if (t.tp.port < 4) {
+			s = "Rx";
+			port_idx = t.tp.port;
+		} else if (t.tp.port < 8) {
+			s = "Tx";
+			port_idx = t.tp.port - 4;
+		} else if (t.tp.port < 12) {
+			s = "loopback";
+			port_idx = t.tp.port - 8;
+		} else if (t.tp.port < 16) {
+			s = "MPS Rx";
+			port_idx = t.tp.port - 12;
+		} else if (t.tp.port < 20) {
+			s = "MPS Tx";
+			port_idx = t.tp.port - 16;
+		} else {
+			s = "unknown";
+			port_idx = t.tp.port;
+		}
+
+		printf("\ntracer %u (currently %s) captures ", t.idx,
+		    t.enabled ? "ENABLED" : "DISABLED");
+		if (t.tp.port < 8)
+			printf("port %u %s, ", port_idx, s);
+		else
+			printf("%s %u, ", s, port_idx);
+		printf("snap length: %u, min length: %u\n", t.tp.snap_len,
+		    t.tp.min_len);
+		printf("packets captured %smatch filter\n",
+		    t.tp.invert ? "do not " : "");
+		if (t.tp.skip_ofst) {
+			printf("filter pattern: ");
+			for (i = 0; i < t.tp.skip_ofst * 2; i += 2)
+				printf("%08x%08x", t.tp.data[i],
+				    t.tp.data[i + 1]);
+			printf("/");
+			for (i = 0; i < t.tp.skip_ofst * 2; i += 2)
+				printf("%08x%08x", t.tp.mask[i],
+				    t.tp.mask[i + 1]);
+			printf("@0\n");
+		}
+		printf("filter pattern: ");
+		for (i = t.tp.skip_ofst * 2; i < T4_TRACE_LEN / 4; i += 2)
+			printf("%08x%08x", t.tp.data[i], t.tp.data[i + 1]);
+		printf("/");
+		for (i = t.tp.skip_ofst * 2; i < T4_TRACE_LEN / 4; i += 2)
+			printf("%08x%08x", t.tp.mask[i], t.tp.mask[i + 1]);
+		printf("@%u\n", (t.tp.skip_ofst + t.tp.skip_len) * 8);
+	}
+
+	return (rc);
+}
+
+static int
+tracer_onoff(uint8_t idx, int enabled)
+{
+	struct t4_tracer t;
+
+	t.idx = idx;
+	t.enabled = enabled;
+	t.valid = 0;
+
+	return doit(CHELSIO_T4_SET_TRACER, &t);
+}
+
+static void
+create_tracing_ifnet()
+{
+	char *cmd[] = {
+		"/sbin/ifconfig", __DECONST(char *, nexus), "create", NULL
+	};
+	char *env[] = {NULL};
+
+	if (vfork() == 0) {
+		close(STDERR_FILENO);
+		execve(cmd[0], cmd, env);
+		_exit(0);
+	}
+}
+
+/*
+ * XXX: Allow user to specify snaplen, minlen, and pattern (including inverted
+ * matching).  Right now this is a quick-n-dirty implementation that traces the
+ * first 128B of all tx or rx on a port
+ */
+static int
+set_tracer(uint8_t idx, int argc, const char *argv[])
+{
+	struct t4_tracer t;
+	int len, port;
+
+	bzero(&t, sizeof (t));
+	t.idx = idx;
+	t.enabled = 1;
+	t.valid = 1;
+
+	if (argc != 1) {
+		warnx("must specify tx<n> or rx<n>.");
+		return (EINVAL);
+	}
+
+	len = strlen(argv[0]);
+	if (len != 3) {
+		warnx("argument must be 3 characters (tx<n> or rx<n>)");
+		return (EINVAL);
+	}
+
+	if (strncmp(argv[0], "tx", 2) == 0) {
+		port = argv[0][2] - '0';
+		if (port < 0 || port > 3) {
+			warnx("'%c' in %s is invalid", argv[0][2], argv[0]);
+			return (EINVAL);
+		}
+		port += 4;
+	} else if (strncmp(argv[0], "rx", 2) == 0) {
+		port = argv[0][2] - '0';
+		if (port < 0 || port > 3) {
+			warnx("'%c' in %s is invalid", argv[0][2], argv[0]);
+			return (EINVAL);
+		}
+	} else {
+		warnx("argument '%s' isn't tx<n> or rx<n>", argv[0]);
+		return (EINVAL);
+	}
+
+	t.tp.snap_len = 128;
+	t.tp.min_len = 0;
+	t.tp.skip_ofst = 0;
+	t.tp.skip_len = 0;
+	t.tp.invert = 0;
+	t.tp.port = port;
+
+	create_tracing_ifnet();
+	return doit(CHELSIO_T4_SET_TRACER, &t);
+}
+
+static int
+tracer_cmd(int argc, const char *argv[])
+{
+	long long val;
+	uint8_t idx;
+	char *s;
+
+	if (argc == 0) {
+		warnx("tracer: no arguments.");
+		return (EINVAL);
+	};
+
+	/* list */
+	if (strcmp(argv[0], "list") == 0) {
+		if (argc != 1)
+			warnx("trailing arguments after \"list\" ignored.");
+
+		return show_tracers();
+	}
+
+	/* <idx> ... */
+	s = str_to_number(argv[0], NULL, &val);
+	if (*s || val > 0xff) {
+		warnx("\"%s\" is neither an index nor a tracer subcommand.",
+		    argv[0]);
+		return (EINVAL);
+	}
+	idx = (int8_t)val;
+
+	/* <idx> disable */
+	if (argc == 2 && strcmp(argv[1], "disable") == 0)
+		return tracer_onoff(idx, 0);
+
+	/* <idx> enable */
+	if (argc == 2 && strcmp(argv[1], "enable") == 0)
+		return tracer_onoff(idx, 1);
+
+	/* <idx> ... */
+	return set_tracer(idx, argc - 1, argv + 1);
+}
+
+static int
 run_cmd(int argc, const char *argv[])
 {
 	int rc = -1;
@@ -1687,6 +1887,8 @@ run_cmd(int argc, const char *argv[])
 		rc = read_i2c(argc, argv);
 	else if (!strcmp(cmd, "clearstats"))
 		rc = clearstats(argc, argv);
+	else if (!strcmp(cmd, "tracer"))
+		rc = tracer_cmd(argc, argv);
 	else {
 		rc = EINVAL;
 		warnx("invalid command \"%s\"", cmd);