[RFC bpf-next 4/5] selftests/bpf: Convert xskxceiver to use custom program

[Stanislav Fomichev <sdf@google.com>]

No functional changes (in theory): convert libxsk-generated
program bytecode to the C code to better illustrate kfunc
metadata (see next patch in the series).

There is also a bunch of unrelated changes, ignore them for the
sake of demo:
- stats.rx_dopped == 2048 vs 2047 ?
- buggy ksft_print_msg calls
- test is limited only to
  TEST_MODE_DRV+TEST_TYPE_RUN_TO_COMPLETION_SINGLE_PKT

Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: Maryam Tahhan <mtahhan@redhat.com>
Cc: xdp-hints@xdp-project.net
Cc: netdev@vger.kernel.org
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/testing/selftests/bpf/Makefile          |  1 +
 .../testing/selftests/bpf/progs/xskxceiver.c  | 21 ++++
 tools/testing/selftests/bpf/xskxceiver.c      | 98 +++++++++++++++----
 tools/testing/selftests/bpf/xskxceiver.h      |  5 +-
 4 files changed, 105 insertions(+), 20 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/xskxceiver.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 79edef1dbda4..3cab2e1b0e74 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -378,6 +378,7 @@ linked_maps.skel.h-deps := linked_maps1.bpf.o linked_maps2.bpf.o
 test_subskeleton.skel.h-deps := test_subskeleton_lib2.bpf.o test_subskeleton_lib.bpf.o test_subskeleton.bpf.o
 test_subskeleton_lib.skel.h-deps := test_subskeleton_lib2.bpf.o test_subskeleton_lib.bpf.o
 test_usdt.skel.h-deps := test_usdt.bpf.o test_usdt_multispec.bpf.o
+xskxceiver-deps := xskxceiver.bpf.o
 
 LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 
diff --git a/tools/testing/selftests/bpf/progs/xskxceiver.c b/tools/testing/selftests/bpf/progs/xskxceiver.c
new file mode 100644
index 000000000000..b135daddad3a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/xskxceiver.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_XSKMAP);
+	__uint(max_entries, 4);
+	__type(key, __u32);
+	__type(value, __u32);
+} xsk SEC(".maps");
+
+SEC("xdp")
+int rx(struct xdp_md *ctx)
+{
+	return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS);
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/xskxceiver.c b/tools/testing/selftests/bpf/xskxceiver.c
index 681a5db80dae..066bd691db13 100644
--- a/tools/testing/selftests/bpf/xskxceiver.c
+++ b/tools/testing/selftests/bpf/xskxceiver.c
@@ -399,6 +399,58 @@ static void usage(const char *prog)
 	ksft_print_msg(str, prog);
 }
 
+static void bpf_update_xsk_map(struct ifobject *ifobject, __u32 queue_id)
+{
+	int map_fd;
+	int sock_fd;
+	int ret;
+
+	map_fd = bpf_map__fd(ifobject->bpf_obj->maps.xsk);
+	sock_fd = xsk_socket__fd(ifobject->xsk->xsk);
+
+	(void)bpf_map_delete_elem(map_fd, &queue_id);
+	ret = bpf_map_update_elem(map_fd, &queue_id, &sock_fd, 0);
+	if (ret)
+		exit_with_error(-ret);
+}
+
+static int bpf_attach(struct ifobject *ifobject)
+{
+	__u32 prog_id = 0;
+
+	bpf_xdp_query_id(ifobject->ifindex, ifobject->xdp_flags, &prog_id);
+	if (prog_id)
+		return 0;
+
+	int ret = bpf_xdp_attach(ifobject->ifindex,
+				 bpf_program__fd(ifobject->bpf_obj->progs.rx),
+				 ifobject->xdp_flags, NULL);
+	if (ret < 0) {
+		if (errno != EEXIST && errno != EBUSY) {
+			exit_with_error(errno);
+		}
+	}
+
+	bpf_update_xsk_map(ifobject, 0);
+
+	return 0;
+}
+
+static void bpf_detach(struct ifobject *ifobject)
+{
+	int my_ns = open("/proc/self/ns/net", O_RDONLY);
+
+	/* Make sure we're in the right namespace when detaching.
+	 * Relevant only for TEST_TYPE_BIDI.
+	 */
+	if (ifobject->ns_fd > 0)
+		setns(ifobject->ns_fd, 0);
+
+	bpf_xdp_detach(ifobject->ifindex, ifobject->xdp_flags, NULL);
+
+	setns(my_ns, 0);
+}
+
 static int switch_namespace(const char *nsname)
 {
 	char fqns[26] = "/var/run/netns/";
@@ -1141,9 +1193,10 @@ static int validate_rx_dropped(struct ifobject *ifobject)
 	if (err)
 		return TEST_FAILURE;
 
-	if (stats.rx_dropped == ifobject->pkt_stream->nb_pkts / 2)
+	if (stats.rx_dropped == ifobject->pkt_stream->nb_pkts / 2 - 1)
 		return TEST_PASS;
 
+	printf("%lld != %d\n", stats.rx_dropped, ifobject->pkt_stream->nb_pkts / 2 - 1);
 	return TEST_FAILURE;
 }
 
@@ -1239,7 +1292,6 @@ static void thread_common_ops_tx(struct test_spec *test, struct ifobject *ifobje
 {
 	xsk_configure_socket(test, ifobject, test->ifobj_rx->umem, true);
 	ifobject->xsk = &ifobject->xsk_arr[0];
-	ifobject->xsk_map_fd = test->ifobj_rx->xsk_map_fd;
 	memcpy(ifobject->umem, test->ifobj_rx->umem, sizeof(struct xsk_umem_info));
 }
 
@@ -1284,6 +1336,14 @@ static void thread_common_ops(struct test_spec *test, struct ifobject *ifobject)
 
 	ifobject->ns_fd = switch_namespace(ifobject->nsname);
 
+	ifindex = if_nametoindex(ifobject->ifname);
+	if (!ifindex)
+		exit_with_error(errno);
+
+	ifobject->bpf_obj = xskxceiver__open_and_load();
+	if (libbpf_get_error(ifobject->bpf_obj))
+		exit_with_error(libbpf_get_error(ifobject->bpf_obj));
+
 	if (ifobject->umem->unaligned_mode)
 		mmap_flags |= MAP_HUGETLB;
 
@@ -1307,11 +1367,8 @@ static void thread_common_ops(struct test_spec *test, struct ifobject *ifobject)
 	if (!ifobject->rx_on)
 		return;
 
-	ifindex = if_nametoindex(ifobject->ifname);
-	if (!ifindex)
-		exit_with_error(errno);
-
-	ret = xsk_setup_xdp_prog_xsk(ifobject->xsk->xsk, &ifobject->xsk_map_fd);
+	ifobject->ifindex = ifindex;
+	ret = bpf_attach(ifobject);
 	if (ret)
 		exit_with_error(-ret);
 
@@ -1321,19 +1378,17 @@ static void thread_common_ops(struct test_spec *test, struct ifobject *ifobject)
 
 	if (ifobject->xdp_flags & XDP_FLAGS_SKB_MODE) {
 		if (opts.attach_mode != XDP_ATTACHED_SKB) {
-			ksft_print_msg("ERROR: [%s] XDP prog not in SKB mode\n");
+			ksft_print_msg("ERROR: XDP prog not in SKB mode\n");
 			exit_with_error(-EINVAL);
 		}
 	} else if (ifobject->xdp_flags & XDP_FLAGS_DRV_MODE) {
 		if (opts.attach_mode != XDP_ATTACHED_DRV) {
-			ksft_print_msg("ERROR: [%s] XDP prog not in DRV mode\n");
+			ksft_print_msg("ERROR: XDP prog not in DRV mode\n");
 			exit_with_error(-EINVAL);
 		}
 	}
 
-	ret = xsk_socket__update_xskmap(ifobject->xsk->xsk, ifobject->xsk_map_fd);
-	if (ret)
-		exit_with_error(-ret);
+	bpf_update_xsk_map(ifobject, 0);
 }
 
 static void *worker_testapp_validate_tx(void *arg)
@@ -1372,8 +1427,7 @@ static void *worker_testapp_validate_rx(void *arg)
 	if (test->current_step == 1) {
 		thread_common_ops(test, ifobject);
 	} else {
-		bpf_map_delete_elem(ifobject->xsk_map_fd, &id);
-		xsk_socket__update_xskmap(ifobject->xsk->xsk, ifobject->xsk_map_fd);
+		bpf_update_xsk_map(ifobject, id);
 	}
 
 	fds.fd = xsk_socket__fd(ifobject->xsk->xsk);
@@ -1481,6 +1535,8 @@ static int testapp_validate_traffic(struct test_spec *test)
 	if (test->total_steps == test->current_step || test->fail) {
 		xsk_socket__delete(ifobj_tx->xsk->xsk);
 		xsk_socket__delete(ifobj_rx->xsk->xsk);
+		bpf_detach(ifobj_tx);
+		bpf_detach(ifobj_rx);
 		testapp_clean_xsk_umem(ifobj_rx);
 		if (!ifobj_tx->shared_umem)
 			testapp_clean_xsk_umem(ifobj_tx);
@@ -1531,16 +1587,12 @@ static void testapp_bidi(struct test_spec *test)
 
 static void swap_xsk_resources(struct ifobject *ifobj_tx, struct ifobject *ifobj_rx)
 {
-	int ret;
-
 	xsk_socket__delete(ifobj_tx->xsk->xsk);
 	xsk_socket__delete(ifobj_rx->xsk->xsk);
 	ifobj_tx->xsk = &ifobj_tx->xsk_arr[1];
 	ifobj_rx->xsk = &ifobj_rx->xsk_arr[1];
 
-	ret = xsk_socket__update_xskmap(ifobj_rx->xsk->xsk, ifobj_rx->xsk_map_fd);
-	if (ret)
-		exit_with_error(-ret);
+	bpf_update_xsk_map(ifobj_tx, 0);
 }
 
 static void testapp_bpf_res(struct test_spec *test)
@@ -1635,6 +1687,8 @@ static bool testapp_unaligned(struct test_spec *test)
 {
 	if (!hugepages_present(test->ifobj_tx)) {
 		ksft_test_result_skip("No 2M huge pages present.\n");
+		bpf_detach(test->ifobj_tx);
+		bpf_detach(test->ifobj_rx);
 		return false;
 	}
 
@@ -1947,10 +2001,16 @@ int main(int argc, char **argv)
 
 	for (i = 0; i < modes; i++)
 		for (j = 0; j < TEST_TYPE_MAX; j++) {
+			if (j != TEST_TYPE_RUN_TO_COMPLETION_SINGLE_PKT) continue; // XXX
+			if (i != TEST_MODE_DRV) continue; // XXX
+
 			test_spec_init(&test, ifobj_tx, ifobj_rx, i);
 			run_pkt_test(&test, i, j);
 			usleep(USLEEP_MAX);
 
+			xskxceiver__destroy(ifobj_tx->bpf_obj);
+			xskxceiver__destroy(ifobj_rx->bpf_obj);
+
 			if (test.fail)
 				failed_tests++;
 		}
diff --git a/tools/testing/selftests/bpf/xskxceiver.h b/tools/testing/selftests/bpf/xskxceiver.h
index edb76d2def9f..c27dcbdb030f 100644
--- a/tools/testing/selftests/bpf/xskxceiver.h
+++ b/tools/testing/selftests/bpf/xskxceiver.h
@@ -5,6 +5,8 @@
 #ifndef XSKXCEIVER_H_
 #define XSKXCEIVER_H_
 
+#include "xskxceiver.skel.h"
+
 #ifndef SOL_XDP
 #define SOL_XDP 283
 #endif
@@ -134,6 +136,7 @@ typedef void *(*thread_func_t)(void *arg);
 struct ifobject {
 	char ifname[MAX_INTERFACE_NAME_CHARS];
 	char nsname[MAX_INTERFACES_NAMESPACE_CHARS];
+	struct xskxceiver *bpf_obj;
 	struct xsk_socket_info *xsk;
 	struct xsk_socket_info *xsk_arr;
 	struct xsk_umem_info *umem;
@@ -141,7 +144,7 @@ struct ifobject {
 	validation_func_t validation_func;
 	struct pkt_stream *pkt_stream;
 	int ns_fd;
-	int xsk_map_fd;
+	int ifindex;
 	u32 dst_ip;
 	u32 src_ip;
 	u32 xdp_flags;
-- 
2.38.1.273.g43a17bfeac-goog