selftests: Add tests for automatic map pinning

This adds a new BPF selftest to exercise the new automatic map pinning
code.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157269298209.394725.15420085139296213182.stgit@toke.dk

tools/testing/selftests/bpf/prog_tests/pinning.c

+// 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)
+{
+	struct bpf_map_info map_info = {};
+	__u32 map_info_len, duration = 0;
+	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"))
+		return 0;
+
+	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;
+}
+
+void test_pinning(void)
+{
+	const char *file_invalid = "./test_pinning_invalid.o";
+	const char *custpinpath = "/sys/fs/bpf/custom/pinmap";
+	const char *nopinpath = "/sys/fs/bpf/nopinmap";
+	const char *nopinpath2 = "/sys/fs/bpf/nopinmap2";
+	const char *custpath = "/sys/fs/bpf/custom";
+	const char *pinpath = "/sys/fs/bpf/pinmap";
+	const char *file = "./test_pinning.o";
+	__u32 map_id, map_id2, duration = 0;
+	struct stat statbuf = {};
+	struct bpf_object *obj;
+	struct bpf_map *map;
+	int err;
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+		.pin_root_path = custpath,
+	);
+
+	/* check that opening fails with invalid pinning value in map def */
+	obj = bpf_object__open_file(file_invalid, NULL);
+	err = libbpf_get_error(obj);
+	if (CHECK(err != -EINVAL, "invalid open", "err %d errno %d\n", err, errno)) {
+		obj = NULL;
+		goto out;
+	}
+
+	/* open the valid object file  */
+	obj = bpf_object__open_file(file, NULL);
+	err = libbpf_get_error(obj);
+	if (CHECK(err, "default open", "err %d errno %d\n", err, errno)) {
+		obj = NULL;
+		goto out;
+	}
+
+	err = bpf_object__load(obj);
+	if (CHECK(err, "default load", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that pinmap was pinned */
+	err = stat(pinpath, &statbuf);
+	if (CHECK(err, "stat pinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that nopinmap was *not* pinned */
+	err = stat(nopinpath, &statbuf);
+	if (CHECK(!err || errno != ENOENT, "stat nopinpath",
+		  "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that nopinmap2 was *not* pinned */
+	err = stat(nopinpath2, &statbuf);
+	if (CHECK(!err || errno != ENOENT, "stat nopinpath2",
+		  "err %d errno %d\n", err, errno))
+		goto out;
+
+	map_id = get_map_id(obj, "pinmap");
+	if (!map_id)
+		goto out;
+
+	bpf_object__close(obj);
+
+	obj = bpf_object__open_file(file, NULL);
+	if (CHECK_FAIL(libbpf_get_error(obj))) {
+		obj = NULL;
+		goto out;
+	}
+
+	err = bpf_object__load(obj);
+	if (CHECK(err, "default load", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that same map ID was reused for second load */
+	map_id2 = get_map_id(obj, "pinmap");
+	if (CHECK(map_id != map_id2, "check reuse",
+		  "err %d errno %d id %d id2 %d\n", err, errno, map_id, map_id2))
+		goto out;
+
+	/* should be no-op to re-pin same map */
+	map = bpf_object__find_map_by_name(obj, "pinmap");
+	if (CHECK(!map, "find map", "NULL map"))
+		goto out;
+
+	err = bpf_map__pin(map, NULL);
+	if (CHECK(err, "re-pin map", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* but error to pin at different location */
+	err = bpf_map__pin(map, "/sys/fs/bpf/other");
+	if (CHECK(!err, "pin map different", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* unpin maps with a pin_path set */
+	err = bpf_object__unpin_maps(obj, NULL);
+	if (CHECK(err, "unpin maps", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* and re-pin them... */
+	err = bpf_object__pin_maps(obj, NULL);
+	if (CHECK(err, "pin maps", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* set pinning path of other map and re-pin all */
+	map = bpf_object__find_map_by_name(obj, "nopinmap");
+	if (CHECK(!map, "find map", "NULL map"))
+		goto out;
+
+	err = bpf_map__set_pin_path(map, custpinpath);
+	if (CHECK(err, "set pin path", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* should only pin the one unpinned map */
+	err = bpf_object__pin_maps(obj, NULL);
+	if (CHECK(err, "pin maps", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that nopinmap was pinned at the custom path */
+	err = stat(custpinpath, &statbuf);
+	if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* remove the custom pin path to re-test it with auto-pinning below */
+	err = unlink(custpinpath);
+	if (CHECK(err, "unlink custpinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = rmdir(custpath);
+	if (CHECK(err, "rmdir custpindir", "err %d errno %d\n", err, errno))
+		goto out;
+
+	bpf_object__close(obj);
+
+	/* open the valid object file again */
+	obj = bpf_object__open_file(file, NULL);
+	err = libbpf_get_error(obj);
+	if (CHECK(err, "default open", "err %d errno %d\n", err, errno)) {
+		obj = NULL;
+		goto out;
+	}
+
+	/* swap pin paths of the two maps */
+	bpf_object__for_each_map(map, obj) {
+		if (!strcmp(bpf_map__name(map), "nopinmap"))
+			err = bpf_map__set_pin_path(map, pinpath);
+		else if (!strcmp(bpf_map__name(map), "pinmap"))
+			err = bpf_map__set_pin_path(map, NULL);
+		else
+			continue;
+
+		if (CHECK(err, "set pin path", "err %d errno %d\n", err, errno))
+			goto out;
+	}
+
+	/* should fail because of map parameter mismatch */
+	err = bpf_object__load(obj);
+	if (CHECK(err != -EINVAL, "param mismatch load", "err %d errno %d\n", err, errno))
+		goto out;
+
+	bpf_object__close(obj);
+
+	/* test auto-pinning at custom path with open opt */
+	obj = bpf_object__open_file(file, &opts);
+	if (CHECK_FAIL(libbpf_get_error(obj))) {
+		obj = NULL;
+		goto out;
+	}
+
+	err = bpf_object__load(obj);
+	if (CHECK(err, "custom load", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that pinmap was pinned at the custom path */
+	err = stat(custpinpath, &statbuf);
+	if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+out:
+	unlink(pinpath);
+	unlink(nopinpath);
+	unlink(nopinpath2);
+	unlink(custpinpath);
+	rmdir(custpath);
+	if (obj)
+		bpf_object__close(obj);
+}

tools/testing/selftests/bpf/progs/test_pinning.c

+// 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_HASH);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} nopinmap SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+	__uint(pinning, LIBBPF_PIN_NONE);
+} nopinmap2 SEC(".maps");
+
+char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/test_pinning_invalid.c

+// 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, 2); /* invalid */
+} nopinmap3 SEC(".maps");
+
+char _license[] SEC("license") = "GPL";