bpf/selftests: coverage for bpf_map_ops errors

These tests expose the issue of being unable to properly check for errors
returned from inlined bpf map helpers that make calls to the bpf_map_ops
functions. At best, a check for zero or non-zero can be done but these
tests show it is not possible to check for a negative value or for a
specific error value.

Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Tested-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230322194754.185781-2-inwardvessel@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 162 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/map_ops.c b/tools/testing/selftests/bpf/prog_tests/map_ops.c
new file mode 100644
index 000000000000..be5e42a413b4
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/map_ops.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <errno.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "test_map_ops.skel.h"
+#include "test_progs.h"
+
+static void map_update(void)
+{
+	(void)syscall(__NR_getpid);
+}
+
+static void map_delete(void)
+{
+	(void)syscall(__NR_getppid);
+}
+
+static void map_push(void)
+{
+	(void)syscall(__NR_getuid);
+}
+
+static void map_pop(void)
+{
+	(void)syscall(__NR_geteuid);
+}
+
+static void map_peek(void)
+{
+	(void)syscall(__NR_getgid);
+}
+
+static void map_for_each_pass(void)
+{
+	(void)syscall(__NR_gettid);
+}
+
+static void map_for_each_fail(void)
+{
+	(void)syscall(__NR_getpgid);
+}
+
+static int setup(struct test_map_ops **skel)
+{
+	int err = 0;
+
+	if (!skel)
+		return -1;
+
+	*skel = test_map_ops__open();
+	if (!ASSERT_OK_PTR(*skel, "test_map_ops__open"))
+		return -1;
+
+	(*skel)->rodata->pid = getpid();
+
+	err = test_map_ops__load(*skel);
+	if (!ASSERT_OK(err, "test_map_ops__load"))
+		return err;
+
+	err = test_map_ops__attach(*skel);
+	if (!ASSERT_OK(err, "test_map_ops__attach"))
+		return err;
+
+	return err;
+}
+
+static void teardown(struct test_map_ops **skel)
+{
+	if (skel && *skel)
+		test_map_ops__destroy(*skel);
+}
+
+static void map_ops_update_delete_subtest(void)
+{
+	struct test_map_ops *skel;
+
+	if (setup(&skel))
+		goto teardown;
+
+	map_update();
+	ASSERT_OK(skel->bss->err, "map_update_initial");
+
+	map_update();
+	ASSERT_LT(skel->bss->err, 0, "map_update_existing");
+	ASSERT_EQ(skel->bss->err, -EEXIST, "map_update_existing");
+
+	map_delete();
+	ASSERT_OK(skel->bss->err, "map_delete_existing");
+
+	map_delete();
+	ASSERT_LT(skel->bss->err, 0, "map_delete_non_existing");
+	ASSERT_EQ(skel->bss->err, -ENOENT, "map_delete_non_existing");
+
+teardown:
+	teardown(&skel);
+}
+
+static void map_ops_push_peek_pop_subtest(void)
+{
+	struct test_map_ops *skel;
+
+	if (setup(&skel))
+		goto teardown;
+
+	map_push();
+	ASSERT_OK(skel->bss->err, "map_push_initial");
+
+	map_push();
+	ASSERT_LT(skel->bss->err, 0, "map_push_when_full");
+	ASSERT_EQ(skel->bss->err, -E2BIG, "map_push_when_full");
+
+	map_peek();
+	ASSERT_OK(skel->bss->err, "map_peek");
+
+	map_pop();
+	ASSERT_OK(skel->bss->err, "map_pop");
+
+	map_peek();
+	ASSERT_LT(skel->bss->err, 0, "map_peek_when_empty");
+	ASSERT_EQ(skel->bss->err, -ENOENT, "map_peek_when_empty");
+
+	map_pop();
+	ASSERT_LT(skel->bss->err, 0, "map_pop_when_empty");
+	ASSERT_EQ(skel->bss->err, -ENOENT, "map_pop_when_empty");
+
+teardown:
+	teardown(&skel);
+}
+
+static void map_ops_for_each_subtest(void)
+{
+	struct test_map_ops *skel;
+
+	if (setup(&skel))
+		goto teardown;
+
+	map_for_each_pass();
+	/* expect to iterate over 1 element */
+	ASSERT_EQ(skel->bss->err, 1, "map_for_each_no_flags");
+
+	map_for_each_fail();
+	ASSERT_LT(skel->bss->err, 0, "map_for_each_with_flags");
+	ASSERT_EQ(skel->bss->err, -EINVAL, "map_for_each_with_flags");
+
+teardown:
+	teardown(&skel);
+}
+
+void test_map_ops(void)
+{
+	if (test__start_subtest("map_ops_update_delete"))
+		map_ops_update_delete_subtest();
+
+	if (test__start_subtest("map_ops_push_peek_pop"))
+		map_ops_push_peek_pop_subtest();
+
+	if (test__start_subtest("map_ops_for_each"))
+		map_ops_for_each_subtest();
+}