selftests/bpf: Add a test for attaching a bpf fentry/fexit trace to an XDP program

// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

#include <net/if.h>

#include "test_xdp.skel.h"

#include "test_xdp_bpf2bpf.skel.h"

void test_xdp_bpf2bpf(void)

{

	__u32 duration = 0, retval, size;

	char buf[128];

	int err, pkt_fd, map_fd;

	struct iphdr *iph = (void *)buf + sizeof(struct ethhdr);

	struct iptnl_info value4 = {.family = AF_INET};

	struct test_xdp *pkt_skel = NULL;

	struct test_xdp_bpf2bpf *ftrace_skel = NULL;

	struct vip key4 = {.protocol = 6, .family = AF_INET};

	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);

	/* Load XDP program to introspect */

	pkt_skel = test_xdp__open_and_load();

	if (CHECK(!pkt_skel, "pkt_skel_load", "test_xdp skeleton failed\n"))

		return;

	pkt_fd = bpf_program__fd(pkt_skel->progs._xdp_tx_iptunnel);

	map_fd = bpf_map__fd(pkt_skel->maps.vip2tnl);

	bpf_map_update_elem(map_fd, &key4, &value4, 0);

	/* Load trace program */

	opts.attach_prog_fd = pkt_fd,

	ftrace_skel = test_xdp_bpf2bpf__open_opts(&opts);

	if (CHECK(!ftrace_skel, "__open", "ftrace skeleton failed\n"))

		goto out;

	err = test_xdp_bpf2bpf__load(ftrace_skel);

	if (CHECK(err, "__load", "ftrace skeleton failed\n"))

		goto out;

	err = test_xdp_bpf2bpf__attach(ftrace_skel);

	if (CHECK(err, "ftrace_attach", "ftrace attach failed: %d\n", err))

		goto out;

	/* Run test program */

	err = bpf_prog_test_run(pkt_fd, 1, &pkt_v4, sizeof(pkt_v4),

				buf, &size, &retval, &duration);

	if (CHECK(err || retval != XDP_TX || size != 74 ||

		  iph->protocol != IPPROTO_IPIP, "ipv4",

		  "err %d errno %d retval %d size %d\n",

		  err, errno, retval, size))

		goto out;

	/* Verify test results */

	if (CHECK(ftrace_skel->bss->test_result_fentry != if_nametoindex("lo"),

		  "result", "fentry failed err %llu\n",

		  ftrace_skel->bss->test_result_fentry))

		goto out;

	CHECK(ftrace_skel->bss->test_result_fexit != XDP_TX, "result",

	      "fexit failed err %llu\n", ftrace_skel->bss->test_result_fexit);

out:

	test_xdp__destroy(pkt_skel);

	test_xdp_bpf2bpf__destroy(ftrace_skel);

}

// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>

#include "bpf_helpers.h"

#include "bpf_trace_helpers.h"

struct net_device {

	/* Structure does not need to contain all entries,

	 * as "preserve_access_index" will use BTF to fix this...

	 */

	int ifindex;

} __attribute__((preserve_access_index));

struct xdp_rxq_info {

	/* Structure does not need to contain all entries,

	 * as "preserve_access_index" will use BTF to fix this...

	 */

	struct net_device *dev;

	__u32 queue_index;

} __attribute__((preserve_access_index));

struct xdp_buff {

	void *data;

	void *data_end;

	void *data_meta;

	void *data_hard_start;

	unsigned long handle;

	struct xdp_rxq_info *rxq;

} __attribute__((preserve_access_index));

__u64 test_result_fentry = 0;

SEC("fentry/_xdp_tx_iptunnel")

int BPF_PROG(trace_on_entry, struct xdp_buff *xdp)

{

	test_result_fentry = xdp->rxq->dev->ifindex;

	return 0;

}

__u64 test_result_fexit = 0;

SEC("fexit/_xdp_tx_iptunnel")

int BPF_PROG(trace_on_exit, struct xdp_buff *xdp, int ret)

{

	test_result_fexit = ret;

	return 0;

}