BPF: Add sample code for new ib_umad tracepoint

Provide a count of class types for a summary of MAD packets.  The example
shows one way to filter the trace data based on management class.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

samples/bpf/ibumad_user.c

@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+
+/**
+ * ibumad BPF sample user side
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * Copyright(c) 2018 Ira Weiny, Intel Corporation
+ */
+
+#include <linux/bpf.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <limits.h>
+
+#include <sys/resource.h>
+#include <getopt.h>
+#include <net/if.h>
+
+#include "bpf_load.h"
+#include "bpf_util.h"
+#include "bpf/libbpf.h"
+
+static void dump_counts(int fd)
+{
+	__u32 key;
+	__u64 value;
+
+	for (key = 0; key < 256; key++) {
+		if (bpf_map_lookup_elem(fd, &key, &value)) {
+			printf("failed to read key %u\n", key);
+			continue;
+		}
+		if (value)
+			printf("0x%02x : %llu\n", key, value);
+	}
+}
+
+static void dump_all_counts(void)
+{
+	printf("Read 'Class : count'\n");
+	dump_counts(map_fd[0]);
+	printf("Write 'Class : count'\n");
+	dump_counts(map_fd[1]);
+}
+
+static void dump_exit(int sig)
+{
+	dump_all_counts();
+	exit(0);
+}
+
+static const struct option long_options[] = {
+	{"help",      no_argument,       NULL, 'h'},
+	{"delay",     required_argument, NULL, 'd'},
+};
+
+static void usage(char *cmd)
+{
+	printf("eBPF test program to count packets from various IP addresses\n"
+		"Usage: %s <options>\n"
+		"       --help,   -h  this menu\n"
+		"       --delay,  -d  <delay>  wait <delay> sec between prints [1 - 1000000]\n"
+		, cmd
+		);
+}
+
+int main(int argc, char **argv)
+{
+	unsigned long delay = 5;
+	int longindex = 0;
+	int opt;
+	char bpf_file[256];
+
+	/* Create the eBPF kernel code path name.
+	 * This follows the pattern of all of the other bpf samples
+	 */
+	snprintf(bpf_file, sizeof(bpf_file), "%s_kern.o", argv[0]);
+
+	/* Do one final dump when exiting */
+	signal(SIGINT, dump_exit);
+	signal(SIGTERM, dump_exit);
+
+	while ((opt = getopt_long(argc, argv, "hd:rSw",
+				  long_options, &longindex)) != -1) {
+		switch (opt) {
+		case 'd':
+			delay = strtoul(optarg, NULL, 0);
+			if (delay == ULONG_MAX || delay < 0 ||
+			    delay > 1000000) {
+				fprintf(stderr, "ERROR: invalid delay : %s\n",
+					optarg);
+				usage(argv[0]);
+				return 1;
+			}
+			break;
+		default:
+		case 'h':
+			usage(argv[0]);
+			return 1;
+		}
+	}
+
+	if (load_bpf_file(bpf_file)) {
+		fprintf(stderr, "ERROR: failed to load eBPF from file : %s\n",
+			bpf_file);
+		return 1;
+	}
+
+	while (1) {
+		sleep(delay);
+		dump_all_counts();
+	}
+
+	return 0;
+}