samples: bpf: Add basic infrastructure for XDP samples

This file implements some common helpers to consolidate differences in
features and functionality between the various XDP samples and give them
a consistent look, feel, and reporting capabilities.

This commit only adds support for receive statistics, which does not
rely on any tracepoint, but on the XDP program installed on the device
by each XDP redirect sample.

Some of the key features are:
 * A concise output format accompanied by helpful text explaining its
   fields.
 * An elaborate output format building upon the concise one, and folding
   out details in case of errors and staying out of view otherwise.
 * Printing driver names for devices redirecting packets.
 * Getting mac address for interface.
 * Printing summarized total statistics for the entire session.
 * Ability to dynamically switch between concise and verbose mode, using
   SIGQUIT (Ctrl + \).

In later patches, the support will be extended for each tracepoint with
its own custom output in concise and verbose mode.
Signed-off-by: NKumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210821002010.845777-4-memxor@gmail.com

samples/bpf/xdp_sample_shared.h

+// SPDX-License-Identifier: GPL-2.0-only
+#ifndef _XDP_SAMPLE_SHARED_H
+#define _XDP_SAMPLE_SHARED_H
+
+struct datarec {
+	size_t processed;
+	size_t dropped;
+	size_t issue;
+	union {
+		size_t xdp_pass;
+		size_t info;
+	};
+	size_t xdp_drop;
+	size_t xdp_redirect;
+} __attribute__((aligned(64)));
+
+#endif

samples/bpf/xdp_sample_user.c

+// SPDX-License-Identifier: GPL-2.0-only
+#define _GNU_SOURCE
+
+#include <arpa/inet.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <linux/ethtool.h>
+#include <linux/hashtable.h>
+#include <linux/if_link.h>
+#include <linux/jhash.h>
+#include <linux/limits.h>
+#include <linux/list.h>
+#include <linux/sockios.h>
+#include <locale.h>
+#include <math.h>
+#include <net/if.h>
+#include <poll.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <sys/signalfd.h>
+#include <sys/sysinfo.h>
+#include <sys/timerfd.h>
+#include <sys/utsname.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "bpf_util.h"
+#include "xdp_sample_user.h"
+
+#define __sample_print(fmt, cond, ...)                                         \
+	({                                                                     \
+		if (cond)                                                      \
+			printf(fmt, ##__VA_ARGS__);                            \
+	})
+
+#define print_always(fmt, ...) __sample_print(fmt, 1, ##__VA_ARGS__)
+#define print_default(fmt, ...)                                                \
+	__sample_print(fmt, sample_log_level & LL_DEFAULT, ##__VA_ARGS__)
+#define __print_err(err, fmt, ...)                                             \
+	({                                                                     \
+		__sample_print(fmt, err > 0 || sample_log_level & LL_DEFAULT,  \
+			       ##__VA_ARGS__);                                 \
+		sample_err_exp = sample_err_exp ? true : err > 0;              \
+	})
+#define print_err(err, fmt, ...) __print_err(err, fmt, ##__VA_ARGS__)
+
+#define __COLUMN(x) "%'10" x " %-13s"
+#define FMT_COLUMNf __COLUMN(".0f")
+#define FMT_COLUMNd __COLUMN("d")
+#define FMT_COLUMNl __COLUMN("llu")
+#define RX(rx) rx, "rx/s"
+#define PPS(pps) pps, "pkt/s"
+#define DROP(drop) drop, "drop/s"
+#define ERR(err) err, "error/s"
+#define HITS(hits) hits, "hit/s"
+#define XMIT(xmit) xmit, "xmit/s"
+#define PASS(pass) pass, "pass/s"
+#define REDIR(redir) redir, "redir/s"
+#define NANOSEC_PER_SEC 1000000000 /* 10^9 */
+
+#define XDP_UNKNOWN (XDP_REDIRECT + 1)
+#define XDP_ACTION_MAX (XDP_UNKNOWN + 1)
+#define XDP_REDIRECT_ERR_MAX 7
+
+enum map_type {
+	MAP_RX,
+	NUM_MAP,
+};
+
+enum log_level {
+	LL_DEFAULT = 1U << 0,
+	LL_SIMPLE = 1U << 1,
+	LL_DEBUG = 1U << 2,
+};
+
+struct record {
+	__u64 timestamp;
+	struct datarec total;
+	struct datarec *cpu;
+};
+
+struct map_entry {
+	struct hlist_node node;
+	__u64 pair;
+	struct record val;
+};
+
+struct stats_record {
+	struct record rx_cnt;
+};
+
+struct sample_output {
+	struct {
+		__u64 rx;
+	} totals;
+	struct {
+		__u64 pps;
+		__u64 drop;
+		__u64 err;
+	} rx_cnt;
+};
+
+struct xdp_desc {
+	int ifindex;
+	__u32 prog_id;
+	int flags;
+} sample_xdp_progs[32];
+
+struct datarec *sample_mmap[NUM_MAP];
+struct bpf_map *sample_map[NUM_MAP];
+size_t sample_map_count[NUM_MAP];
+enum log_level sample_log_level;
+struct sample_output sample_out;
+unsigned long sample_interval;
+bool sample_err_exp;
+int sample_xdp_cnt;
+int sample_n_cpus;
+int sample_sig_fd;
+int sample_mask;
+
+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);
+		return UINT64_MAX;
+	}
+	return (__u64)t.tv_sec * NANOSEC_PER_SEC + t.tv_nsec;
+}
+
+static void sample_print_help(int mask)
+{
+	printf("Output format description\n\n"
+	       "By default, redirect success statistics are disabled, use -s to enable.\n"
+	       "The terse output mode is default, verbose mode can be activated using -v\n"
+	       "Use SIGQUIT (Ctrl + \\) to switch the mode dynamically at runtime\n\n"
+	       "Terse mode displays at most the following fields:\n"
+	       "  rx/s        Number of packets received per second\n"
+	       "  redir/s     Number of packets successfully redirected per second\n"
+	       "  err,drop/s  Aggregated count of errors per second (including dropped packets)\n"
+	       "  xmit/s      Number of packets transmitted on the output device per second\n\n"
+	       "Output description for verbose mode:\n"
+	       "  FIELD                 DESCRIPTION\n");
+
+	if (mask & SAMPLE_RX_CNT) {
+		printf("  receive\t\tDisplays the number of packets received & errors encountered\n"
+		       " \t\t\tWhenever an error or packet drop occurs, details of per CPU error\n"
+		       " \t\t\tand drop statistics will be expanded inline in terse mode.\n"
+		       " \t\t\t\tpkt/s     - Packets received per second\n"
+		       " \t\t\t\tdrop/s    - Packets dropped per second\n"
+		       " \t\t\t\terror/s   - Errors encountered per second\n\n");
+	}
+}
+
+void sample_usage(char *argv[], const struct option *long_options,
+		  const char *doc, int mask, bool error)
+{
+	int i;
+
+	if (!error)
+		sample_print_help(mask);
+
+	printf("\n%s\nOption for %s:\n", doc, argv[0]);
+	for (i = 0; long_options[i].name != 0; i++) {
+		printf(" --%-15s", long_options[i].name);
+		if (long_options[i].flag != NULL)
+			printf(" flag (internal value: %d)",
+			       *long_options[i].flag);
+		else
+			printf("\t short-option: -%c", long_options[i].val);
+		printf("\n");
+	}
+	printf("\n");
+}
+
+static struct datarec *alloc_record_per_cpu(void)
+{
+	unsigned int nr_cpus = libbpf_num_possible_cpus();
+	struct datarec *array;
+
+	array = calloc(nr_cpus, sizeof(*array));
+	if (!array) {
+		fprintf(stderr, "Failed to allocate memory (nr_cpus: %u)\n",
+			nr_cpus);
+		return NULL;
+	}
+	return array;
+}
+
+static int map_entry_init(struct map_entry *e, __u64 pair)
+{
+	e->pair = pair;
+	INIT_HLIST_NODE(&e->node);
+	e->val.timestamp = gettime();
+	e->val.cpu = alloc_record_per_cpu();
+	if (!e->val.cpu)
+		return -ENOMEM;
+	return 0;
+}
+
+static void map_collect_percpu(struct datarec *values, struct record *rec)
+{
+	/* For percpu maps, userspace gets a value per possible CPU */
+	unsigned int nr_cpus = libbpf_num_possible_cpus();
+	__u64 sum_xdp_redirect = 0;
+	__u64 sum_processed = 0;
+	__u64 sum_xdp_pass = 0;
+	__u64 sum_xdp_drop = 0;
+	__u64 sum_dropped = 0;
+	__u64 sum_issue = 0;
+	int i;
+
+	/* 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 = READ_ONCE(values[i].processed);
+		rec->cpu[i].dropped = READ_ONCE(values[i].dropped);
+		rec->cpu[i].issue = READ_ONCE(values[i].issue);
+		rec->cpu[i].xdp_pass = READ_ONCE(values[i].xdp_pass);
+		rec->cpu[i].xdp_drop = READ_ONCE(values[i].xdp_drop);
+		rec->cpu[i].xdp_redirect = READ_ONCE(values[i].xdp_redirect);
+
+		sum_processed += rec->cpu[i].processed;
+		sum_dropped += rec->cpu[i].dropped;
+		sum_issue += rec->cpu[i].issue;
+		sum_xdp_pass += rec->cpu[i].xdp_pass;
+		sum_xdp_drop += rec->cpu[i].xdp_drop;
+		sum_xdp_redirect += rec->cpu[i].xdp_redirect;
+	}
+
+	rec->total.processed = sum_processed;
+	rec->total.dropped = sum_dropped;
+	rec->total.issue = sum_issue;
+	rec->total.xdp_pass = sum_xdp_pass;
+	rec->total.xdp_drop = sum_xdp_drop;
+	rec->total.xdp_redirect = sum_xdp_redirect;
+}
+
+static struct stats_record *alloc_stats_record(void)
+{
+	struct stats_record *rec;
+	int i;
+
+	rec = calloc(1, sizeof(*rec) + sample_n_cpus * sizeof(struct record));
+	if (!rec) {
+		fprintf(stderr, "Failed to allocate memory\n");
+		return NULL;
+	}
+
+	if (sample_mask & SAMPLE_RX_CNT) {
+		rec->rx_cnt.cpu = alloc_record_per_cpu();
+		if (!rec->rx_cnt.cpu) {
+			fprintf(stderr,
+				"Failed to allocate rx_cnt per-CPU array\n");
+			goto end_rec;
+		}
+	}
+
+	return rec;
+end_rec:
+	free(rec);
+	return NULL;
+}
+
+static void free_stats_record(struct stats_record *r)
+{
+	struct hlist_node *tmp;
+	struct map_entry *e;
+	int i;
+
+	free(r->rx_cnt.cpu);
+	free(r);
+}
+
+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 double sample_round(double val)
+{
+	if (val - floor(val) < 0.5)
+		return floor(val);
+	return ceil(val);
+}
+
+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 = sample_round(packets / period_);
+	}
+	return pps;
+}
+
+static __u64 calc_drop_pps(struct datarec *r, struct datarec *p, double period_)
+{
+	__u64 packets = 0;
+	__u64 pps = 0;
+
+	if (period_ > 0) {
+		packets = r->dropped - p->dropped;
+		pps = sample_round(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 = sample_round(packets / period_);
+	}
+	return pps;
+}
+
+static __u64 calc_info_pps(struct datarec *r, struct datarec *p, double period_)
+{
+	__u64 packets = 0;
+	__u64 pps = 0;
+
+	if (period_ > 0) {
+		packets = r->info - p->info;
+		pps = sample_round(packets / period_);
+	}
+	return pps;
+}
+
+static void calc_xdp_pps(struct datarec *r, struct datarec *p, double *xdp_pass,
+			 double *xdp_drop, double *xdp_redirect, double period_)
+{
+	*xdp_pass = 0, *xdp_drop = 0, *xdp_redirect = 0;
+	if (period_ > 0) {
+		*xdp_redirect = (r->xdp_redirect - p->xdp_redirect) / period_;
+		*xdp_pass = (r->xdp_pass - p->xdp_pass) / period_;
+		*xdp_drop = (r->xdp_drop - p->xdp_drop) / period_;
+	}
+}
+
+static void stats_get_rx_cnt(struct stats_record *stats_rec,
+			     struct stats_record *stats_prev,
+			     unsigned int nr_cpus, struct sample_output *out)
+{
+	struct record *rec, *prev;
+	double t, pps, drop, err;
+	int i;
+
+	rec = &stats_rec->rx_cnt;
+	prev = &stats_prev->rx_cnt;
+	t = calc_period(rec, prev);
+
+	for (i = 0; i < nr_cpus; i++) {
+		struct datarec *r = &rec->cpu[i];
+		struct datarec *p = &prev->cpu[i];
+		char str[64];
+
+		pps = calc_pps(r, p, t);
+		drop = calc_drop_pps(r, p, t);
+		err = calc_errs_pps(r, p, t);
+		if (!pps && !drop && !err)
+			continue;
+
+		snprintf(str, sizeof(str), "cpu:%d", i);
+		print_default("    %-18s " FMT_COLUMNf FMT_COLUMNf FMT_COLUMNf
+			      "\n",
+			      str, PPS(pps), DROP(drop), ERR(err));
+	}
+
+	if (out) {
+		pps = calc_pps(&rec->total, &prev->total, t);
+		drop = calc_drop_pps(&rec->total, &prev->total, t);
+		err = calc_errs_pps(&rec->total, &prev->total, t);
+
+		out->rx_cnt.pps = pps;
+		out->rx_cnt.drop = drop;
+		out->rx_cnt.err = err;
+		out->totals.rx += pps;
+		out->totals.drop += drop;
+		out->totals.err += err;
+	}
+}
+
+
+static void stats_print(const char *prefix, int mask, struct stats_record *r,
+			struct stats_record *p, struct sample_output *out)
+{
+	int nr_cpus = libbpf_num_possible_cpus();
+	const char *str;
+
+	print_always("%-23s", prefix ?: "Summary");
+	if (mask & SAMPLE_RX_CNT)
+		print_always(FMT_COLUMNl, RX(out->totals.rx));
+	printf("\n");
+
+	if (mask & SAMPLE_RX_CNT) {
+		str = (sample_log_level & LL_DEFAULT) && out->rx_cnt.pps ?
+				    "receive total" :
+				    "receive";
+		print_err((out->rx_cnt.err || out->rx_cnt.drop),
+			  "  %-20s " FMT_COLUMNl FMT_COLUMNl FMT_COLUMNl "\n",
+			  str, PPS(out->rx_cnt.pps), DROP(out->rx_cnt.drop),
+			  ERR(out->rx_cnt.err));
+
+		stats_get_rx_cnt(r, p, nr_cpus, NULL);
+	}
+
+	if (sample_log_level & LL_DEFAULT ||
+	    ((sample_log_level & LL_SIMPLE) && sample_err_exp)) {
+		sample_err_exp = false;
+		printf("\n");
+	}
+}
+
+int sample_setup_maps(struct bpf_map **maps)
+{
+	sample_n_cpus = libbpf_num_possible_cpus();
+
+	for (int i = 0; i < NUM_MAP; i++) {
+		sample_map[i] = maps[i];
+
+		switch (i) {
+		case MAP_RX:
+			sample_map_count[i] = sample_n_cpus;
+			break;
+		default:
+			return -EINVAL;
+		}
+		if (bpf_map__resize(sample_map[i], sample_map_count[i]) < 0)
+			return -errno;
+	}
+	return 0;
+}
+
+static int sample_setup_maps_mappings(void)
+{
+	for (int i = 0; i < NUM_MAP; i++) {
+		size_t size = sample_map_count[i] * sizeof(struct datarec);
+
+		sample_mmap[i] = mmap(NULL, size, PROT_READ | PROT_WRITE,
+				      MAP_SHARED, bpf_map__fd(sample_map[i]), 0);
+		if (sample_mmap[i] == MAP_FAILED)
+			return -errno;
+	}
+	return 0;
+}
+
+int __sample_init(int mask)
+{
+	sigset_t st;
+
+	sigemptyset(&st);
+	sigaddset(&st, SIGQUIT);
+	sigaddset(&st, SIGINT);
+	sigaddset(&st, SIGTERM);
+
+	if (sigprocmask(SIG_BLOCK, &st, NULL) < 0)
+		return -errno;
+
+	sample_sig_fd = signalfd(-1, &st, SFD_CLOEXEC | SFD_NONBLOCK);
+	if (sample_sig_fd < 0)
+		return -errno;
+
+	sample_mask = mask;
+
+	return sample_setup_maps_mappings();
+}
+
+static int __sample_remove_xdp(int ifindex, __u32 prog_id, int xdp_flags)
+{
+	__u32 cur_prog_id = 0;
+	int ret;
+
+	if (prog_id) {
+		ret = bpf_get_link_xdp_id(ifindex, &cur_prog_id, xdp_flags);
+		if (ret < 0)
+			return -errno;
+
+		if (prog_id != cur_prog_id) {
+			print_always(
+				"Program on ifindex %d does not match installed "
+				"program, skipping unload\n",
+				ifindex);
+			return -ENOENT;
+		}
+	}
+
+	return bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+}
+
+int sample_install_xdp(struct bpf_program *xdp_prog, int ifindex, bool generic,
+		       bool force)
+{
+	int ret, xdp_flags = 0;
+	__u32 prog_id = 0;
+
+	if (sample_xdp_cnt == 32) {
+		fprintf(stderr,
+			"Total limit for installed XDP programs in a sample reached\n");
+		return -ENOTSUP;
+	}
+
+	xdp_flags |= !force ? XDP_FLAGS_UPDATE_IF_NOEXIST : 0;
+	xdp_flags |= generic ? XDP_FLAGS_SKB_MODE : XDP_FLAGS_DRV_MODE;
+	ret = bpf_set_link_xdp_fd(ifindex, bpf_program__fd(xdp_prog),
+				  xdp_flags);
+	if (ret < 0) {
+		ret = -errno;
+		fprintf(stderr,
+			"Failed to install program \"%s\" on ifindex %d, mode = %s, "
+			"force = %s: %s\n",
+			bpf_program__name(xdp_prog), ifindex,
+			generic ? "skb" : "native", force ? "true" : "false",
+			strerror(-ret));
+		return ret;
+	}
+
+	ret = bpf_get_link_xdp_id(ifindex, &prog_id, xdp_flags);
+	if (ret < 0) {
+		ret = -errno;
+		fprintf(stderr,
+			"Failed to get XDP program id for ifindex %d, removing program: %s\n",
+			ifindex, strerror(errno));
+		__sample_remove_xdp(ifindex, 0, xdp_flags);
+		return ret;
+	}
+	sample_xdp_progs[sample_xdp_cnt++] =
+		(struct xdp_desc){ ifindex, prog_id, xdp_flags };
+
+	return 0;
+}
+
+static void sample_summary_print(void)
+{
+	double period = sample_out.rx_cnt.pps;
+
+	if (sample_out.totals.rx) {
+		double pkts = sample_out.totals.rx;
+
+		print_always("  Packets received    : %'-10llu\n",
+			     sample_out.totals.rx);
+		print_always("  Average packets/s   : %'-10.0f\n",
+			     sample_round(pkts / period));
+	}
+}
+
+void sample_exit(int status)
+{
+	size_t size;
+
+	for (int i = 0; i < NUM_MAP; i++) {
+		size = sample_map_count[i] * sizeof(**sample_mmap);
+		munmap(sample_mmap[i], size);
+	}
+	while (sample_xdp_cnt--) {
+		int i = sample_xdp_cnt, ifindex, xdp_flags;
+		__u32 prog_id;
+
+		prog_id = sample_xdp_progs[i].prog_id;
+		ifindex = sample_xdp_progs[i].ifindex;
+		xdp_flags = sample_xdp_progs[i].flags;
+
+		__sample_remove_xdp(ifindex, prog_id, xdp_flags);
+	}
+	sample_summary_print();
+	close(sample_sig_fd);
+	exit(status);
+}
+
+static int sample_stats_collect(struct stats_record *rec)
+{
+	int i;
+
+	if (sample_mask & SAMPLE_RX_CNT)
+		map_collect_percpu(sample_mmap[MAP_RX], &rec->rx_cnt);
+
+	return 0;
+}
+
+static void sample_summary_update(struct sample_output *out, int interval)
+{
+	sample_out.totals.rx += out->totals.rx;
+	sample_out.rx_cnt.pps += interval;
+}
+
+static void sample_stats_print(int mask, struct stats_record *cur,
+			       struct stats_record *prev, char *prog_name,
+			       int interval)
+{
+	struct sample_output out = {};
+
+	if (mask & SAMPLE_RX_CNT)
+		stats_get_rx_cnt(cur, prev, 0, &out);
+	sample_summary_update(&out, interval);
+
+	stats_print(prog_name, mask, cur, prev, &out);
+}
+
+void sample_switch_mode(void)
+{
+	sample_log_level ^= LL_DEBUG - 1;
+}
+
+static int sample_signal_cb(void)
+{
+	struct signalfd_siginfo si;
+	int r;
+
+	r = read(sample_sig_fd, &si, sizeof(si));
+	if (r < 0)
+		return -errno;
+
+	switch (si.ssi_signo) {
+	case SIGQUIT:
+		sample_switch_mode();
+		printf("\n");
+		break;
+	default:
+		printf("\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+/* Pointer swap trick */
+static void swap(struct stats_record **a, struct stats_record **b)
+{
+	struct stats_record *tmp;
+
+	tmp = *a;
+	*a = *b;
+	*b = tmp;
+}
+
+static int sample_timer_cb(int timerfd, struct stats_record **rec,
+			   struct stats_record **prev, int interval)
+{
+	char line[64] = "Summary";
+	int ret;
+	__u64 t;
+
+	ret = read(timerfd, &t, sizeof(t));
+	if (ret < 0)
+		return -errno;
+
+	swap(prev, rec);
+	ret = sample_stats_collect(*rec);
+	if (ret < 0)
+		return ret;
+
+	if (sample_xdp_cnt == 2) {
+		char fi[IFNAMSIZ];
+		char to[IFNAMSIZ];
+		const char *f, *t;
+
+		f = t = NULL;
+		if (if_indextoname(sample_xdp_progs[0].ifindex, fi))
+			f = fi;
+		if (if_indextoname(sample_xdp_progs[1].ifindex, to))
+			t = to;
+
+		snprintf(line, sizeof(line), "%s->%s", f ?: "?", t ?: "?");
+	}
+
+	sample_stats_print(sample_mask, *rec, *prev, line, interval);
+	return 0;
+}
+
+int sample_run(int interval, void (*post_cb)(void *), void *ctx)
+{
+	struct timespec ts = { interval, 0 };
+	struct itimerspec its = { ts, ts };
+	struct stats_record *rec, *prev;
+	struct pollfd pfd[2] = {};
+	int timerfd, ret;
+
+	if (!interval) {
+		fprintf(stderr, "Incorrect interval 0\n");
+		return -EINVAL;
+	}
+	sample_interval = interval;
+	/* Pretty print numbers */
+	setlocale(LC_NUMERIC, "en_US.UTF-8");
+
+	timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC | TFD_NONBLOCK);
+	if (timerfd < 0)
+		return -errno;
+	timerfd_settime(timerfd, 0, &its, NULL);
+
+	pfd[0].fd = sample_sig_fd;
+	pfd[0].events = POLLIN;
+
+	pfd[1].fd = timerfd;
+	pfd[1].events = POLLIN;
+
+	ret = -ENOMEM;
+	rec = alloc_stats_record();
+	if (!rec)
+		goto end;
+	prev = alloc_stats_record();
+	if (!prev)
+		goto end_rec;
+
+	ret = sample_stats_collect(rec);
+	if (ret < 0)
+		goto end_rec_prev;
+
+	for (;;) {
+		ret = poll(pfd, 2, -1);
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+			else
+				break;
+		}
+
+		if (pfd[0].revents & POLLIN)
+			ret = sample_signal_cb();
+		else if (pfd[1].revents & POLLIN)
+			ret = sample_timer_cb(timerfd, &rec, &prev, interval);
+
+		if (ret)
+			break;
+
+		if (post_cb)
+			post_cb(ctx);
+	}
+
+end_rec_prev:
+	free_stats_record(prev);
+end_rec:
+	free_stats_record(rec);
+end:
+	close(timerfd);
+
+	return ret;
+}
+
+const char *get_driver_name(int ifindex)
+{
+	struct ethtool_drvinfo drv = {};
+	char ifname[IF_NAMESIZE];
+	static char drvname[32];
+	struct ifreq ifr = {};
+	int fd, r = 0;
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0)
+		return "[error]";
+
+	if (!if_indextoname(ifindex, ifname))
+		goto end;
+
+	drv.cmd = ETHTOOL_GDRVINFO;
+	safe_strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+	ifr.ifr_data = (void *)&drv;
+
+	r = ioctl(fd, SIOCETHTOOL, &ifr);
+	if (r)
+		goto end;
+
+	safe_strncpy(drvname, drv.driver, sizeof(drvname));
+
+	close(fd);
+	return drvname;
+
+end:
+	r = errno;
+	close(fd);
+	return r == EOPNOTSUPP ? "loopback" : "[error]";
+}
+
+int get_mac_addr(int ifindex, void *mac_addr)
+{
+	char ifname[IF_NAMESIZE];
+	struct ifreq ifr = {};
+	int fd, r;
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0)
+		return -errno;
+
+	if (!if_indextoname(ifindex, ifname)) {
+		r = -errno;
+		goto end;
+	}
+
+	safe_strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+
+	r = ioctl(fd, SIOCGIFHWADDR, &ifr);
+	if (r) {
+		r = -errno;
+		goto end;
+	}
+
+	memcpy(mac_addr, ifr.ifr_hwaddr.sa_data, 6 * sizeof(char));
+
+end:
+	close(fd);
+	return r;
+}
+
+__attribute__((constructor)) static void sample_ctor(void)
+{
+	if (libbpf_set_strict_mode(LIBBPF_STRICT_ALL) < 0) {
+		fprintf(stderr, "Failed to set libbpf strict mode: %s\n",
+			strerror(errno));
+		/* Just exit, nothing to cleanup right now */
+		exit(EXIT_FAIL_BPF);
+	}
+}

samples/bpf/xdp_sample_user.h

+// SPDX-License-Identifier: GPL-2.0-only
+#ifndef XDP_SAMPLE_USER_H
+#define XDP_SAMPLE_USER_H
+
+#include <bpf/libbpf.h>
+#include <linux/compiler.h>
+
+#include "xdp_sample_shared.h"
+
+enum stats_mask {
+	_SAMPLE_REDIRECT_MAP        = 1U << 0,
+	SAMPLE_RX_CNT               = 1U << 1,
+};
+
+/* 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
+
+int sample_setup_maps(struct bpf_map **maps);
+int __sample_init(int mask);
+void sample_exit(int status);
+int sample_run(int interval, void (*post_cb)(void *), void *ctx);
+
+void sample_switch_mode(void);
+int sample_install_xdp(struct bpf_program *xdp_prog, int ifindex, bool generic,
+		       bool force);
+void sample_usage(char *argv[], const struct option *long_options,
+		  const char *doc, int mask, bool error);
+
+const char *get_driver_name(int ifindex);
+int get_mac_addr(int ifindex, void *mac_addr);
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-truncation"
+__attribute__((unused))
+static inline char *safe_strncpy(char *dst, const char *src, size_t size)
+{
+	if (!size)
+		return dst;
+	strncpy(dst, src, size - 1);
+	dst[size - 1] = '\0';
+	return dst;
+}
+#pragma GCC diagnostic pop
+
+#define DEFINE_SAMPLE_INIT(name)                                               \
+	static int sample_init(struct name *skel, int mask)                    \
+	{                                                                      \
+		int ret;                                                       \
+		ret = __sample_init(mask);                                     \
+		if (ret < 0)                                                   \
+			return ret;                                            \
+		return 0;                                                      \
+	}
+
+#endif