--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0
+ * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
+ */
+static const char *__doc__ = " XDP RX-queue info extract example\n\n"
+       "Monitor how many packets per sec (pps) are received\n"
+       "per NIC RX queue index and which CPU processed the packet\n"
+       ;
+
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <locale.h>
+#include <sys/resource.h>
+#include <getopt.h>
+#include <net/if.h>
+#include <time.h>
+
+#include <arpa/inet.h>
+#include <linux/if_link.h>
+
+#include "libbpf.h"
+#include "bpf_load.h"
+#include "bpf_util.h"
+
+static int ifindex = -1;
+static char ifname_buf[IF_NAMESIZE];
+static char *ifname;
+
+static __u32 xdp_flags;
+
+/* Exit return codes */
+#define EXIT_OK                0
+#define EXIT_FAIL              1
+#define EXIT_FAIL_OPTION       2
+#define EXIT_FAIL_XDP          3
+#define EXIT_FAIL_BPF          4
+#define EXIT_FAIL_MEM          5
+
+static const struct option long_options[] = {
+       {"help",        no_argument,            NULL, 'h' },
+       {"dev",         required_argument,      NULL, 'd' },
+       {"skb-mode",    no_argument,            NULL, 'S' },
+       {"sec",         required_argument,      NULL, 's' },
+       {"no-separators", no_argument,          NULL, 'z' },
+       {"action",      required_argument,      NULL, 'a' },
+       {0, 0, NULL,  0 }
+};
+
+static void int_exit(int sig)
+{
+       fprintf(stderr,
+               "Interrupted: Removing XDP program on ifindex:%d device:%s\n",
+               ifindex, ifname);
+       if (ifindex > -1)
+               set_link_xdp_fd(ifindex, -1, xdp_flags);
+       exit(EXIT_OK);
+}
+
+struct config {
+       __u32 action;
+       int ifindex;
+};
+#define XDP_ACTION_MAX (XDP_TX + 1)
+#define XDP_ACTION_MAX_STRLEN 11
+static const char *xdp_action_names[XDP_ACTION_MAX] = {
+       [XDP_ABORTED]   = "XDP_ABORTED",
+       [XDP_DROP]      = "XDP_DROP",
+       [XDP_PASS]      = "XDP_PASS",
+       [XDP_TX]        = "XDP_TX",
+};
+
+static const char *action2str(int action)
+{
+       if (action < XDP_ACTION_MAX)
+               return xdp_action_names[action];
+       return NULL;
+}
+
+static int parse_xdp_action(char *action_str)
+{
+       size_t maxlen;
+       __u64 action = -1;
+       int i;
+
+       for (i = 0; i < XDP_ACTION_MAX; i++) {
+               maxlen = XDP_ACTION_MAX_STRLEN;
+               if (strncmp(xdp_action_names[i], action_str, maxlen) == 0) {
+                       action = i;
+                       break;
+               }
+       }
+       return action;
+}
+
+static void list_xdp_actions(void)
+{
+       int i;
+
+       printf("Available XDP --action <options>\n");
+       for (i = 0; i < XDP_ACTION_MAX; i++)
+               printf("\t%s\n", xdp_action_names[i]);
+       printf("\n");
+}
+
+static void usage(char *argv[])
+{
+       int i;
+
+       printf("\nDOCUMENTATION:\n%s\n", __doc__);
+       printf(" Usage: %s (options-see-below)\n", argv[0]);
+       printf(" Listing options:\n");
+       for (i = 0; long_options[i].name != 0; i++) {
+               printf(" --%-12s", long_options[i].name);
+               if (long_options[i].flag != NULL)
+                       printf(" flag (internal value:%d)",
+                               *long_options[i].flag);
+               else
+                       printf(" short-option: -%c",
+                               long_options[i].val);
+               printf("\n");
+       }
+       printf("\n");
+       list_xdp_actions();
+}
+
+#define NANOSEC_PER_SEC 1000000000 /* 10^9 */
+static __u64 gettime(void)
+{
+       struct timespec t;
+       int res;
+
+       res = clock_gettime(CLOCK_MONOTONIC, &t);
+       if (res < 0) {
+               fprintf(stderr, "Error with gettimeofday! (%i)\n", res);
+               exit(EXIT_FAIL);
+       }
+       return (__u64) t.tv_sec * NANOSEC_PER_SEC + t.tv_nsec;
+}
+
+/* Common stats data record shared with _kern.c */
+struct datarec {
+       __u64 processed;
+       __u64 issue;
+};
+struct record {
+       __u64 timestamp;
+       struct datarec total;
+       struct datarec *cpu;
+};
+struct stats_record {
+       struct record stats;
+       struct record *rxq;
+};
+
+static struct datarec *alloc_record_per_cpu(void)
+{
+       unsigned int nr_cpus = bpf_num_possible_cpus();
+       struct datarec *array;
+       size_t size;
+
+       size = sizeof(struct datarec) * nr_cpus;
+       array = malloc(size);
+       memset(array, 0, size);
+       if (!array) {
+               fprintf(stderr, "Mem alloc error (nr_cpus:%u)\n", nr_cpus);
+               exit(EXIT_FAIL_MEM);
+       }
+       return array;
+}
+
+static struct record *alloc_record_per_rxq(void)
+{
+       unsigned int nr_rxqs = map_data[2].def.max_entries;
+       struct record *array;
+       size_t size;
+
+       size = sizeof(struct record) * nr_rxqs;
+       array = malloc(size);
+       memset(array, 0, size);
+       if (!array) {
+               fprintf(stderr, "Mem alloc error (nr_rxqs:%u)\n", nr_rxqs);
+               exit(EXIT_FAIL_MEM);
+       }
+       return array;
+}
+
+static struct stats_record *alloc_stats_record(void)
+{
+       unsigned int nr_rxqs = map_data[2].def.max_entries;
+       struct stats_record *rec;
+       int i;
+
+       rec = malloc(sizeof(*rec));
+       memset(rec, 0, sizeof(*rec));
+       if (!rec) {
+               fprintf(stderr, "Mem alloc error\n");
+               exit(EXIT_FAIL_MEM);
+       }
+       rec->rxq = alloc_record_per_rxq();
+       for (i = 0; i < nr_rxqs; i++)
+               rec->rxq[i].cpu = alloc_record_per_cpu();
+
+       rec->stats.cpu = alloc_record_per_cpu();
+       return rec;
+}
+
+static void free_stats_record(struct stats_record *r)
+{
+       unsigned int nr_rxqs = map_data[2].def.max_entries;
+       int i;
+
+       for (i = 0; i < nr_rxqs; i++)
+               free(r->rxq[i].cpu);
+
+       free(r->rxq);
+       free(r->stats.cpu);
+       free(r);
+}
+
+static bool map_collect_percpu(int fd, __u32 key, struct record *rec)
+{
+       /* For percpu maps, userspace gets a value per possible CPU */
+       unsigned int nr_cpus = bpf_num_possible_cpus();
+       struct datarec values[nr_cpus];
+       __u64 sum_processed = 0;
+       __u64 sum_issue = 0;
+       int i;
+
+       if ((bpf_map_lookup_elem(fd, &key, values)) != 0) {
+               fprintf(stderr,
+                       "ERR: bpf_map_lookup_elem failed key:0x%X\n", key);
+               return false;
+       }
+       /* Get time as close as possible to reading map contents */
+       rec->timestamp = gettime();
+
+       /* Record and sum values from each CPU */
+       for (i = 0; i < nr_cpus; i++) {
+               rec->cpu[i].processed = values[i].processed;
+               sum_processed        += values[i].processed;
+               rec->cpu[i].issue = values[i].issue;
+               sum_issue        += values[i].issue;
+       }
+       rec->total.processed = sum_processed;
+       rec->total.issue     = sum_issue;
+       return true;
+}
+
+static void stats_collect(struct stats_record *rec)
+{
+       int fd, i, max_rxqs;
+
+       fd = map_data[1].fd; /* map: stats_global_map */
+       map_collect_percpu(fd, 0, &rec->stats);
+
+       fd = map_data[2].fd; /* map: rx_queue_index_map */
+       max_rxqs = map_data[2].def.max_entries;
+       for (i = 0; i < max_rxqs; i++)
+               map_collect_percpu(fd, i, &rec->rxq[i]);
+}
+
+static double calc_period(struct record *r, struct record *p)
+{
+       double period_ = 0;
+       __u64 period = 0;
+
+       period = r->timestamp - p->timestamp;
+       if (period > 0)
+               period_ = ((double) period / NANOSEC_PER_SEC);
+
+       return period_;
+}
+
+static __u64 calc_pps(struct datarec *r, struct datarec *p, double period_)
+{
+       __u64 packets = 0;
+       __u64 pps = 0;
+
+       if (period_ > 0) {
+               packets = r->processed - p->processed;
+               pps = packets / period_;
+       }
+       return pps;
+}
+
+static __u64 calc_errs_pps(struct datarec *r,
+                           struct datarec *p, double period_)
+{
+       __u64 packets = 0;
+       __u64 pps = 0;
+
+       if (period_ > 0) {
+               packets = r->issue - p->issue;
+               pps = packets / period_;
+       }
+       return pps;
+}
+
+static void stats_print(struct stats_record *stats_rec,
+                       struct stats_record *stats_prev,
+                       int action)
+{
+       unsigned int nr_cpus = bpf_num_possible_cpus();
+       unsigned int nr_rxqs = map_data[2].def.max_entries;
+       double pps = 0, err = 0;
+       struct record *rec, *prev;
+       double t;
+       int rxq;
+       int i;
+
+       /* Header */
+       printf("\nRunning XDP on dev:%s (ifindex:%d) action:%s\n",
+              ifname, ifindex, action2str(action));
+
+       /* stats_global_map */
+       {
+               char *fmt_rx = "%-15s %-7d %'-11.0f %'-10.0f %s\n";
+               char *fm2_rx = "%-15s %-7s %'-11.0f\n";
+               char *errstr = "";
+
+               printf("%-15s %-7s %-11s %-11s\n",
+                      "XDP stats", "CPU", "pps", "issue-pps");
+
+               rec  =  &stats_rec->stats;
+               prev = &stats_prev->stats;
+               t = calc_period(rec, prev);
+               for (i = 0; i < nr_cpus; i++) {
+                       struct datarec *r = &rec->cpu[i];
+                       struct datarec *p = &prev->cpu[i];
+
+                       pps = calc_pps     (r, p, t);
+                       err = calc_errs_pps(r, p, t);
+                       if (err > 0)
+                               errstr = "invalid-ifindex";
+                       if (pps > 0)
+                               printf(fmt_rx, "XDP-RX CPU",
+                                       i, pps, err, errstr);
+               }
+               pps  = calc_pps     (&rec->total, &prev->total, t);
+               err  = calc_errs_pps(&rec->total, &prev->total, t);
+               printf(fm2_rx, "XDP-RX CPU", "total", pps, err);
+       }
+
+       /* rx_queue_index_map */
+       printf("\n%-15s %-7s %-11s %-11s\n",
+              "RXQ stats", "RXQ:CPU", "pps", "issue-pps");
+
+       for (rxq = 0; rxq < nr_rxqs; rxq++) {
+               char *fmt_rx = "%-15s %3d:%-3d %'-11.0f %'-10.0f %s\n";
+               char *fm2_rx = "%-15s %3d:%-3s %'-11.0f\n";
+               char *errstr = "";
+               int rxq_ = rxq;
+
+               /* Last RXQ in map catch overflows */
+               if (rxq_ == nr_rxqs - 1)
+                       rxq_ = -1;
+
+               rec  =  &stats_rec->rxq[rxq];
+               prev = &stats_prev->rxq[rxq];
+               t = calc_period(rec, prev);
+               for (i = 0; i < nr_cpus; i++) {
+                       struct datarec *r = &rec->cpu[i];
+                       struct datarec *p = &prev->cpu[i];
+
+                       pps = calc_pps     (r, p, t);
+                       err = calc_errs_pps(r, p, t);
+                       if (err > 0) {
+                               if (rxq_ == -1)
+                                       errstr = "map-overflow-RXQ";
+                               else
+                                       errstr = "err";
+                       }
+                       if (pps > 0)
+                               printf(fmt_rx, "rx_queue_index",
+                                      rxq_, i, pps, err, errstr);
+               }
+               pps  = calc_pps     (&rec->total, &prev->total, t);
+               err  = calc_errs_pps(&rec->total, &prev->total, t);
+               if (pps || err)
+                       printf(fm2_rx, "rx_queue_index", rxq_, "sum", pps, err);
+       }
+}
+
+
+/* Pointer swap trick */
+static inline void swap(struct stats_record **a, struct stats_record **b)
+{
+       struct stats_record *tmp;
+
+       tmp = *a;
+       *a = *b;
+       *b = tmp;
+}
+
+static void stats_poll(int interval, int action)
+{
+       struct stats_record *record, *prev;
+
+       record = alloc_stats_record();
+       prev   = alloc_stats_record();
+       stats_collect(record);
+
+       while (1) {
+               swap(&prev, &record);
+               stats_collect(record);
+               stats_print(record, prev, action);
+               sleep(interval);
+       }
+
+       free_stats_record(record);
+       free_stats_record(prev);
+}
+
+
+int main(int argc, char **argv)
+{
+       struct rlimit r = {10 * 1024 * 1024, RLIM_INFINITY};
+       bool use_separators = true;
+       struct config cfg = { 0 };
+       char filename[256];
+       int longindex = 0;
+       int interval = 2;
+       __u32 key = 0;
+       int opt, err;
+
+       char action_str_buf[XDP_ACTION_MAX_STRLEN + 1 /* for \0 */] = { 0 };
+       int action = XDP_PASS; /* Default action */
+       char *action_str = NULL;
+
+       snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+       if (setrlimit(RLIMIT_MEMLOCK, &r)) {
+               perror("setrlimit(RLIMIT_MEMLOCK)");
+               return 1;
+       }
+
+       if (load_bpf_file(filename)) {
+               fprintf(stderr, "ERR in load_bpf_file(): %s", bpf_log_buf);
+               return EXIT_FAIL;
+       }
+
+       if (!prog_fd[0]) {
+               fprintf(stderr, "ERR: load_bpf_file: %s\n", strerror(errno));
+               return EXIT_FAIL;
+       }
+
+       /* Parse commands line args */
+       while ((opt = getopt_long(argc, argv, "hSd:",
+                                 long_options, &longindex)) != -1) {
+               switch (opt) {
+               case 'd':
+                       if (strlen(optarg) >= IF_NAMESIZE) {
+                               fprintf(stderr, "ERR: --dev name too long\n");
+                               goto error;
+                       }
+                       ifname = (char *)&ifname_buf;
+                       strncpy(ifname, optarg, IF_NAMESIZE);
+                       ifindex = if_nametoindex(ifname);
+                       if (ifindex == 0) {
+                               fprintf(stderr,
+                                       "ERR: --dev name unknown err(%d):%s\n",
+                                       errno, strerror(errno));
+                               goto error;
+                       }
+                       break;
+               case 's':
+                       interval = atoi(optarg);
+                       break;
+               case 'S':
+                       xdp_flags |= XDP_FLAGS_SKB_MODE;
+                       break;
+               case 'z':
+                       use_separators = false;
+                       break;
+               case 'a':
+                       action_str = (char *)&action_str_buf;
+                       strncpy(action_str, optarg, XDP_ACTION_MAX_STRLEN);
+                       break;
+               case 'h':
+               error:
+               default:
+                       usage(argv);
+                       return EXIT_FAIL_OPTION;
+               }
+       }
+       /* Required option */
+       if (ifindex == -1) {
+               fprintf(stderr, "ERR: required option --dev missing\n");
+               usage(argv);
+               return EXIT_FAIL_OPTION;
+       }
+       cfg.ifindex = ifindex;
+
+       /* Parse action string */
+       if (action_str) {
+               action = parse_xdp_action(action_str);
+               if (action < 0) {
+                       fprintf(stderr, "ERR: Invalid XDP --action: %s\n",
+                               action_str);
+                       list_xdp_actions();
+                       return EXIT_FAIL_OPTION;
+               }
+       }
+       cfg.action = action;
+
+       /* Trick to pretty printf with thousands separators use %' */
+       if (use_separators)
+               setlocale(LC_NUMERIC, "en_US");
+
+       /* User-side setup ifindex in config_map */
+       err = bpf_map_update_elem(map_fd[0], &key, &cfg, 0);
+       if (err) {
+               fprintf(stderr, "Store config failed (err:%d)\n", err);
+               exit(EXIT_FAIL_BPF);
+       }
+
+       /* Remove XDP program when program is interrupted */
+       signal(SIGINT, int_exit);
+
+       if (set_link_xdp_fd(ifindex, prog_fd[0], xdp_flags) < 0) {
+               fprintf(stderr, "link set xdp fd failed\n");
+               return EXIT_FAIL_XDP;
+       }
+
+       stats_poll(interval, action);
+       return EXIT_OK;
+}