[RFC PATCH bpf-next 4/4] selftests/bpf: add bpf_trace_btf helper tests

[Alan Maguire <alan.maguire@oracle.com>]

Basic tests verifying various flag combinations for bpf_trace_btf()
using a tp_btf program to trace skb data.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 tools/testing/selftests/bpf/prog_tests/trace_btf.c | 45 ++++++++++++++++++++++
 .../selftests/bpf/progs/netif_receive_skb.c        | 43 +++++++++++++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/trace_btf.c
 create mode 100644 tools/testing/selftests/bpf/progs/netif_receive_skb.c

diff --git a/tools/testing/selftests/bpf/prog_tests/trace_btf.c b/tools/testing/selftests/bpf/prog_tests/trace_btf.c
new file mode 100644
index 0000000..e64b69d
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/trace_btf.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+#include "netif_receive_skb.skel.h"
+
+void test_trace_btf(void)
+{
+	struct netif_receive_skb *skel;
+	struct netif_receive_skb__bss *bss;
+	int err, duration = 0;
+
+	skel = netif_receive_skb__open();
+	if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+		return;
+
+	err = netif_receive_skb__load(skel);
+	if (CHECK(err, "skel_load", "failed to load skeleton: %d\n", err))
+		goto cleanup;
+
+	bss = skel->bss;
+
+	err = netif_receive_skb__attach(skel);
+	if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
+		goto cleanup;
+
+	/* generate receive event */
+	system("ping -c 10 127.0.0.1");
+
+	/*
+	 * Make sure netif_receive_skb program was triggered
+	 * and it set expected return values from bpf_trace_printk()s
+	 * and all tests ran.
+	 */
+	if (CHECK(bss->ret <= 0,
+		  "bpf_trace_btf: got return value",
+		  "ret <= 0 %ld test %d\n", bss->ret, bss->num_subtests))
+		goto cleanup;
+
+	CHECK(bss->num_subtests != bss->ran_subtests, "check all subtests ran",
+	      "only ran %d of %d tests\n", bss->num_subtests,
+	      bss->ran_subtests);
+
+cleanup:
+	netif_receive_skb__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/netif_receive_skb.c b/tools/testing/selftests/bpf/progs/netif_receive_skb.c
new file mode 100644
index 0000000..cab764e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/netif_receive_skb.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020, Oracle and/or its affiliates. */
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+long ret = 0;
+int num_subtests = 0;
+int ran_subtests = 0;
+
+#define CHECK_TRACE(_p, flags)						 \
+	do {								 \
+		++num_subtests;						 \
+		if (ret >= 0) {						 \
+			++ran_subtests;					 \
+			ret = bpf_trace_btf(_p, sizeof(*(_p)), 0, flags);\
+		}							 \
+	} while (0)
+
+/* TRACE_EVENT(netif_receive_skb,
+ *	TP_PROTO(struct sk_buff *skb),
+ */
+SEC("tp_btf/netif_receive_skb")
+int BPF_PROG(trace_netif_receive_skb, struct sk_buff *skb)
+{
+	static const char skb_type[] = "struct sk_buff";
+	static struct btf_ptr p = { };
+
+	p.ptr = skb;
+	p.type = skb_type;
+
+	CHECK_TRACE(&p, 0);
+	CHECK_TRACE(&p, BTF_TRACE_F_COMPACT);
+	CHECK_TRACE(&p, BTF_TRACE_F_NONAME);
+	CHECK_TRACE(&p, BTF_TRACE_F_PTR_RAW);
+	CHECK_TRACE(&p, BTF_TRACE_F_ZERO);
+	CHECK_TRACE(&p, BTF_TRACE_F_COMPACT | BTF_TRACE_F_NONAME |
+		    BTF_TRACE_F_PTR_RAW | BTF_TRACE_F_ZERO);
+
+	return 0;
+}
-- 
1.8.3.1