[PATCH bpf-next v3 4/4] selftests: Add tests for automatic map pinning

["Toke Høiland-Jørgensen" <toke@redhat.com>]

From: Toke Høiland-Jørgensen <toke@redhat.com>

This adds a new BPF selftest to exercise the new automatic map pinning
code.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 tools/testing/selftests/bpf/prog_tests/pinning.c |   91 ++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/test_pinning.c |   29 +++++++
 2 files changed, 120 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/pinning.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_pinning.c

diff --git a/tools/testing/selftests/bpf/prog_tests/pinning.c b/tools/testing/selftests/bpf/prog_tests/pinning.c
new file mode 100644
index 000000000000..d4a63de72f5a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/pinning.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <test_progs.h>
+
+__u32 get_map_id(struct bpf_object *obj, const char *name)
+{
+	__u32 map_info_len, duration, retval;
+	struct bpf_map_info map_info = {};
+	struct bpf_map *map;
+	int err;
+
+	map_info_len = sizeof(map_info);
+
+	map = bpf_object__find_map_by_name(obj, name);
+	if (!CHECK(!map, "find map", "NULL map")) {
+		err = bpf_obj_get_info_by_fd(bpf_map__fd(map),
+					     &map_info, &map_info_len);
+		CHECK(err, "get map info", "err %d errno %d", err, errno);
+		return map_info.id;
+	}
+	return 0;
+}
+
+void test_pinning(void)
+{
+	__u32 duration, retval, size, map_id, map_id2;
+	const char *custpinpath = "/sys/fs/bpf/custom/pinmap";
+	const char *nopinpath = "/sys/fs/bpf/nopinmap";
+	const char *custpath = "/sys/fs/bpf/custom";
+	const char *pinpath = "/sys/fs/bpf/pinmap";
+	const char *file = "./test_pinning.o";
+	struct stat statbuf = {};
+	struct bpf_object *obj;
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+		.auto_pin_path = custpath,
+	);
+
+	int err;
+	obj = bpf_object__open_file(file, NULL);
+	if (CHECK_FAIL(libbpf_get_error(obj)))
+		return;
+
+	err = bpf_object__load(obj);
+	CHECK(err, "default load", "err %d errno %d\n", err, errno);
+
+	/* check that pinmap was pinned */
+	err = stat(pinpath, &statbuf);
+	CHECK(err, "stat pinpath", "err %d errno %d\n", err, errno);
+
+        /* check that nopinmap was *not* pinned */
+	err = stat(nopinpath, &statbuf);
+	CHECK(errno != ENOENT, "stat nopinpath", "err %d errno %d\n", err, errno);
+
+        map_id = get_map_id(obj, "pinmap");
+	bpf_object__close(obj);
+
+	obj = bpf_object__open_file(file, NULL);
+	if (CHECK_FAIL(libbpf_get_error(obj)))
+		return;
+
+	err = bpf_object__load(obj);
+	CHECK(err, "default load", "err %d errno %d\n", err, errno);
+
+	/* check that same map ID was reused for second load */
+	map_id2 = get_map_id(obj, "pinmap");
+	CHECK(map_id != map_id2, "check reuse",
+	      "err %d errno %d id %d id2 %d\n", err, errno, map_id, map_id2);
+	unlink(pinpath);
+	bpf_object__close(obj);
+
+	err = mkdir(custpath, 0700);
+	CHECK(err, "mkdir custpath",  "err %d errno %d\n", err, errno);
+
+	obj = bpf_object__open_file(file, &opts);
+	if (CHECK_FAIL(libbpf_get_error(obj)))
+		return;
+
+	err = bpf_object__load(obj);
+	CHECK(err, "custom load", "err %d errno %d\n", err, errno);
+
+	/* check that pinmap was pinned at the custom path */
+	err = stat(custpinpath, &statbuf);
+	CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno);
+
+	unlink(custpinpath);
+	rmdir(custpath);
+	bpf_object__close(obj);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_pinning.c b/tools/testing/selftests/bpf/progs/test_pinning.c
new file mode 100644
index 000000000000..ff2d7447777e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_pinning.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+int _version SEC("version") = 1;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+	__uint(pinning, LIBBPF_PIN_BY_NAME);
+} pinmap SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} nopinmap SEC(".maps");
+
+SEC("xdp_prog")
+int _xdp_prog(struct xdp_md *xdp)
+{
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";