samples/bpf: Remove the xdp_sample_pkts utility

The functionality of this utility is covered by the xdpdump utility in
xdp-tools.

There's a slight difference in usage as the xdpdump utility's main focus is
to dump packets before or after they are processed by an existing XDP
program. However, xdpdump also has the --load-xdp-program switch, which
will make it attach its own program if no existing program is loaded. With
this, xdp_sample_pkts usage can be converted as:

xdp_sample_pkts eth0
  --> xdpdump --load-xdp-program eth0

To get roughly equivalent behaviour.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20230824102255.1561885-6-toke@redhat.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf/Makefile

@@ -44,7 +44,6 @@ tprogs-y += cpustat
 tprogs-y += xdp_adjust_tail
 tprogs-y += xdp_fwd
 tprogs-y += task_fd_query
-tprogs-y += xdp_sample_pkts
 tprogs-y += ibumad
 tprogs-y += hbm
 
@@ -95,7 +94,6 @@ cpustat-objs := cpustat_user.o
 xdp_adjust_tail-objs := xdp_adjust_tail_user.o
 xdp_fwd-objs := xdp_fwd_user.o
 task_fd_query-objs := task_fd_query_user.o $(TRACE_HELPERS)
-xdp_sample_pkts-objs := xdp_sample_pkts_user.o
 ibumad-objs := ibumad_user.o
 hbm-objs := hbm.o $(CGROUP_HELPERS)
 
@@ -148,7 +146,6 @@ always-y += cpustat_kern.o
 always-y += xdp_adjust_tail_kern.o
 always-y += xdp_fwd_kern.o
 always-y += task_fd_query_kern.o
-always-y += xdp_sample_pkts_kern.o
 always-y += ibumad_kern.o
 always-y += hbm_out_kern.o
 always-y += hbm_edt_kern.o

samples/bpf/xdp_sample_pkts_kern.c

-// SPDX-License-Identifier: GPL-2.0
-#include <linux/ptrace.h>
-#include <linux/version.h>
-#include <uapi/linux/bpf.h>
-#include <bpf/bpf_helpers.h>
-
-#define SAMPLE_SIZE 64ul
-
-struct {
-	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
-	__uint(key_size, sizeof(int));
-	__uint(value_size, sizeof(u32));
-} my_map SEC(".maps");
-
-SEC("xdp_sample")
-int xdp_sample_prog(struct xdp_md *ctx)
-{
-	void *data_end = (void *)(long)ctx->data_end;
-	void *data = (void *)(long)ctx->data;
-
-	/* Metadata will be in the perf event before the packet data. */
-	struct S {
-		u16 cookie;
-		u16 pkt_len;
-	} __packed metadata;
-
-	if (data < data_end) {
-		/* The XDP perf_event_output handler will use the upper 32 bits
-		 * of the flags argument as a number of bytes to include of the
-		 * packet payload in the event data. If the size is too big, the
-		 * call to bpf_perf_event_output will fail and return -EFAULT.
-		 *
-		 * See bpf_xdp_event_output in net/core/filter.c.
-		 *
-		 * The BPF_F_CURRENT_CPU flag means that the event output fd
-		 * will be indexed by the CPU number in the event map.
-		 */
-		u64 flags = BPF_F_CURRENT_CPU;
-		u16 sample_size;
-		int ret;
-
-		metadata.cookie = 0xdead;
-		metadata.pkt_len = (u16)(data_end - data);
-		sample_size = min(metadata.pkt_len, SAMPLE_SIZE);
-		flags |= (u64)sample_size << 32;
-
-		ret = bpf_perf_event_output(ctx, &my_map, flags,
-					    &metadata, sizeof(metadata));
-		if (ret)
-			bpf_printk("perf_event_output failed: %d\n", ret);
-	}
-
-	return XDP_PASS;
-}
-
-char _license[] SEC("license") = "GPL";
-u32 _version SEC("version") = LINUX_VERSION_CODE;

samples/bpf/xdp_sample_pkts_user.c

-// SPDX-License-Identifier: GPL-2.0
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <linux/perf_event.h>
-#include <linux/bpf.h>
-#include <net/if.h>
-#include <errno.h>
-#include <assert.h>
-#include <sys/sysinfo.h>
-#include <sys/ioctl.h>
-#include <signal.h>
-#include <bpf/libbpf.h>
-#include <bpf/bpf.h>
-#include <libgen.h>
-#include <linux/if_link.h>
-
-#include "perf-sys.h"
-
-static int if_idx;
-static char *if_name;
-static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
-static __u32 prog_id;
-static struct perf_buffer *pb = NULL;
-
-static int do_attach(int idx, int fd, const char *name)
-{
-	struct bpf_prog_info info = {};
-	__u32 info_len = sizeof(info);
-	int err;
-
-	err = bpf_xdp_attach(idx, fd, xdp_flags, NULL);
-	if (err < 0) {
-		printf("ERROR: failed to attach program to %s\n", name);
-		return err;
-	}
-
-	err = bpf_prog_get_info_by_fd(fd, &info, &info_len);
-	if (err) {
-		printf("can't get prog info - %s\n", strerror(errno));
-		return err;
-	}
-	prog_id = info.id;
-
-	return err;
-}
-
-static int do_detach(int idx, const char *name)
-{
-	__u32 curr_prog_id = 0;
-	int err = 0;
-
-	err = bpf_xdp_query_id(idx, xdp_flags, &curr_prog_id);
-	if (err) {
-		printf("bpf_xdp_query_id failed\n");
-		return err;
-	}
-	if (prog_id == curr_prog_id) {
-		err = bpf_xdp_detach(idx, xdp_flags, NULL);
-		if (err < 0)
-			printf("ERROR: failed to detach prog from %s\n", name);
-	} else if (!curr_prog_id) {
-		printf("couldn't find a prog id on a %s\n", name);
-	} else {
-		printf("program on interface changed, not removing\n");
-	}
-
-	return err;
-}
-
-#define SAMPLE_SIZE 64
-
-static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
-{
-	struct {
-		__u16 cookie;
-		__u16 pkt_len;
-		__u8  pkt_data[SAMPLE_SIZE];
-	} __packed *e = data;
-	int i;
-
-	if (e->cookie != 0xdead) {
-		printf("BUG cookie %x sized %d\n", e->cookie, size);
-		return;
-	}
-
-	printf("Pkt len: %-5d bytes. Ethernet hdr: ", e->pkt_len);
-	for (i = 0; i < 14 && i < e->pkt_len; i++)
-		printf("%02x ", e->pkt_data[i]);
-	printf("\n");
-}
-
-static void sig_handler(int signo)
-{
-	do_detach(if_idx, if_name);
-	perf_buffer__free(pb);
-	exit(0);
-}
-
-static void usage(const char *prog)
-{
-	fprintf(stderr,
-		"%s: %s [OPTS] <ifname|ifindex>\n\n"
-		"OPTS:\n"
-		"    -F    force loading prog\n"
-		"    -S    use skb-mode\n",
-		__func__, prog);
-}
-
-int main(int argc, char **argv)
-{
-	const char *optstr = "FS";
-	int prog_fd, map_fd, opt;
-	struct bpf_program *prog;
-	struct bpf_object *obj;
-	struct bpf_map *map;
-	char filename[256];
-	int ret, err;
-
-	while ((opt = getopt(argc, argv, optstr)) != -1) {
-		switch (opt) {
-		case 'F':
-			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
-			break;
-		case 'S':
-			xdp_flags |= XDP_FLAGS_SKB_MODE;
-			break;
-		default:
-			usage(basename(argv[0]));
-			return 1;
-		}
-	}
-
-	if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
-		xdp_flags |= XDP_FLAGS_DRV_MODE;
-
-	if (optind == argc) {
-		usage(basename(argv[0]));
-		return 1;
-	}
-
-	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
-
-	obj = bpf_object__open_file(filename, NULL);
-	if (libbpf_get_error(obj))
-		return 1;
-
-	prog = bpf_object__next_program(obj, NULL);
-	bpf_program__set_type(prog, BPF_PROG_TYPE_XDP);
-
-	err = bpf_object__load(obj);
-	if (err)
-		return 1;
-
-	prog_fd = bpf_program__fd(prog);
-
-	map = bpf_object__next_map(obj, NULL);
-	if (!map) {
-		printf("finding a map in obj file failed\n");
-		return 1;
-	}
-	map_fd = bpf_map__fd(map);
-
-	if_idx = if_nametoindex(argv[optind]);
-	if (!if_idx)
-		if_idx = strtoul(argv[optind], NULL, 0);
-
-	if (!if_idx) {
-		fprintf(stderr, "Invalid ifname\n");
-		return 1;
-	}
-	if_name = argv[optind];
-	err = do_attach(if_idx, prog_fd, if_name);
-	if (err)
-		return err;
-
-	if (signal(SIGINT, sig_handler) ||
-	    signal(SIGHUP, sig_handler) ||
-	    signal(SIGTERM, sig_handler)) {
-		perror("signal");
-		return 1;
-	}
-
-	pb = perf_buffer__new(map_fd, 8, print_bpf_output, NULL, NULL, NULL);
-	err = libbpf_get_error(pb);
-	if (err) {
-		perror("perf_buffer setup failed");
-		return 1;
-	}
-
-	while ((ret = perf_buffer__poll(pb, 1000)) >= 0) {
-	}
-
-	kill(0, SIGINT);
-	return ret;
-}