bpf: Add bpf_xdp_output() helper

Introduce new helper that reuses existing xdp perf_event output
implementation, but can be called from raw_tracepoint programs
that receive 'struct xdp_buff *' as a tracepoint argument.

Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158348514556.2239.11050972434793741444.stgit@xdp-tutorial

1 files changed, 53 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c
index 4ba011031d4c..a0f688c37023 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c
@@ -4,17 +4,51 @@
 #include "test_xdp.skel.h"
 #include "test_xdp_bpf2bpf.skel.h"
 
+struct meta {
+	int ifindex;
+	int pkt_len;
+};
+
+static void on_sample(void *ctx, int cpu, void *data, __u32 size)
+{
+	int duration = 0;
+	struct meta *meta = (struct meta *)data;
+	struct ipv4_packet *trace_pkt_v4 = data + sizeof(*meta);
+
+	if (CHECK(size < sizeof(pkt_v4) + sizeof(*meta),
+		  "check_size", "size %u < %zu\n",
+		  size, sizeof(pkt_v4) + sizeof(*meta)))
+		return;
+
+	if (CHECK(meta->ifindex != if_nametoindex("lo"), "check_meta_ifindex",
+		  "meta->ifindex = %d\n", meta->ifindex))
+		return;
+
+	if (CHECK(meta->pkt_len != sizeof(pkt_v4), "check_meta_pkt_len",
+		  "meta->pkt_len = %zd\n", sizeof(pkt_v4)))
+		return;
+
+	if (CHECK(memcmp(trace_pkt_v4, &pkt_v4, sizeof(pkt_v4)),
+		  "check_packet_content", "content not the same\n"))
+		return;
+
+	*(bool *)ctx = true;
+}
+
 void test_xdp_bpf2bpf(void)
 {
 	__u32 duration = 0, retval, size;
 	char buf[128];
 	int err, pkt_fd, map_fd;
+	bool passed = false;
 	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};
 	struct bpf_program *prog;
+	struct perf_buffer *pb = NULL;
+	struct perf_buffer_opts pb_opts = {};
 
 	/* Load XDP program to introspect */
 	pkt_skel = test_xdp__open_and_load();
@@ -50,6 +84,14 @@ void test_xdp_bpf2bpf(void)
 	if (CHECK(err, "ftrace_attach", "ftrace attach failed: %d\n", err))
 		goto out;
 
+	/* Set up perf buffer */
+	pb_opts.sample_cb = on_sample;
+	pb_opts.ctx = &passed;
+	pb = perf_buffer__new(bpf_map__fd(ftrace_skel->maps.perf_buf_map),
+			      1, &pb_opts);
+	if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
+		goto out;
+
 	/* Run test program */
 	err = bpf_prog_test_run(pkt_fd, 1, &pkt_v4, sizeof(pkt_v4),
 				buf, &size, &retval, &duration);
@@ -60,6 +102,15 @@ void test_xdp_bpf2bpf(void)
 		  err, errno, retval, size))
 		goto out;
 
+	/* Make sure bpf_xdp_output() was triggered and it sent the expected
+	 * data to the perf ring buffer.
+	 */
+	err = perf_buffer__poll(pb, 100);
+	if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
+		goto out;
+
+	CHECK_FAIL(!passed);
+
 	/* Verify test results */
 	if (CHECK(ftrace_skel->bss->test_result_fentry != if_nametoindex("lo"),
 		  "result", "fentry failed err %llu\n",
@@ -70,6 +121,8 @@ void test_xdp_bpf2bpf(void)
 	      "fexit failed err %llu\n", ftrace_skel->bss->test_result_fexit);
 
 out:
+	if (pb)
+		perf_buffer__free(pb);
 	test_xdp__destroy(pkt_skel);
 	test_xdp_bpf2bpf__destroy(ftrace_skel);
 }