bpf, selftest: test global data/bss/rodata sections

Add tests for libbpf relocation of static variable references
into the .data, .rodata and .bss sections of the ELF, also add
read-only test for .rodata. All passing:

  # ./test_progs
  [...]
  test_global_data:PASS:load program 0 nsec
  test_global_data:PASS:pass global data run 925 nsec
  test_global_data_number:PASS:relocate .bss reference 925 nsec
  test_global_data_number:PASS:relocate .data reference 925 nsec
  test_global_data_number:PASS:relocate .rodata reference 925 nsec
  test_global_data_number:PASS:relocate .bss reference 925 nsec
  test_global_data_number:PASS:relocate .data reference 925 nsec
  test_global_data_number:PASS:relocate .rodata reference 925 nsec
  test_global_data_number:PASS:relocate .bss reference 925 nsec
  test_global_data_number:PASS:relocate .bss reference 925 nsec
  test_global_data_number:PASS:relocate .rodata reference 925 nsec
  test_global_data_number:PASS:relocate .rodata reference 925 nsec
  test_global_data_number:PASS:relocate .rodata reference 925 nsec
  test_global_data_string:PASS:relocate .rodata reference 925 nsec
  test_global_data_string:PASS:relocate .data reference 925 nsec
  test_global_data_string:PASS:relocate .bss reference 925 nsec
  test_global_data_string:PASS:relocate .data reference 925 nsec
  test_global_data_string:PASS:relocate .bss reference 925 nsec
  test_global_data_struct:PASS:relocate .rodata reference 925 nsec
  test_global_data_struct:PASS:relocate .bss reference 925 nsec
  test_global_data_struct:PASS:relocate .rodata reference 925 nsec
  test_global_data_struct:PASS:relocate .data reference 925 nsec
  test_global_data_rdonly:PASS:test .rodata read-only map 925 nsec
  [...]
  Summary: 229 PASSED, 0 FAILED

Note map helper signatures have been changed to avoid warnings
when passing in const data.

Joint work with Daniel Borkmann.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 157 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/global_data.c b/tools/testing/selftests/bpf/prog_tests/global_data.c
new file mode 100644
index 000000000000..d011079fb0bf
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/global_data.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+static void test_global_data_number(struct bpf_object *obj, __u32 duration)
+{
+	int i, err, map_fd;
+	uint64_t num;
+
+	map_fd = bpf_find_map(__func__, obj, "result_number");
+	if (map_fd < 0) {
+		error_cnt++;
+		return;
+	}
+
+	struct {
+		char *name;
+		uint32_t key;
+		uint64_t num;
+	} tests[] = {
+		{ "relocate .bss reference",     0, 0 },
+		{ "relocate .data reference",    1, 42 },
+		{ "relocate .rodata reference",  2, 24 },
+		{ "relocate .bss reference",     3, 0 },
+		{ "relocate .data reference",    4, 0xffeeff },
+		{ "relocate .rodata reference",  5, 0xabab },
+		{ "relocate .bss reference",     6, 1234 },
+		{ "relocate .bss reference",     7, 0 },
+		{ "relocate .rodata reference",  8, 0xab },
+		{ "relocate .rodata reference",  9, 0x1111111111111111 },
+		{ "relocate .rodata reference", 10, ~0 },
+	};
+
+	for (i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+		err = bpf_map_lookup_elem(map_fd, &tests[i].key, &num);
+		CHECK(err || num != tests[i].num, tests[i].name,
+		      "err %d result %lx expected %lx\n",
+		      err, num, tests[i].num);
+	}
+}
+
+static void test_global_data_string(struct bpf_object *obj, __u32 duration)
+{
+	int i, err, map_fd;
+	char str[32];
+
+	map_fd = bpf_find_map(__func__, obj, "result_string");
+	if (map_fd < 0) {
+		error_cnt++;
+		return;
+	}
+
+	struct {
+		char *name;
+		uint32_t key;
+		char str[32];
+	} tests[] = {
+		{ "relocate .rodata reference", 0, "abcdefghijklmnopqrstuvwxyz" },
+		{ "relocate .data reference",   1, "abcdefghijklmnopqrstuvwxyz" },
+		{ "relocate .bss reference",    2, "" },
+		{ "relocate .data reference",   3, "abcdexghijklmnopqrstuvwxyz" },
+		{ "relocate .bss reference",    4, "\0\0hello" },
+	};
+
+	for (i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+		err = bpf_map_lookup_elem(map_fd, &tests[i].key, str);
+		CHECK(err || memcmp(str, tests[i].str, sizeof(str)),
+		      tests[i].name, "err %d result \'%s\' expected \'%s\'\n",
+		      err, str, tests[i].str);
+	}
+}
+
+struct foo {
+	__u8  a;
+	__u32 b;
+	__u64 c;
+};
+
+static void test_global_data_struct(struct bpf_object *obj, __u32 duration)
+{
+	int i, err, map_fd;
+	struct foo val;
+
+	map_fd = bpf_find_map(__func__, obj, "result_struct");
+	if (map_fd < 0) {
+		error_cnt++;
+		return;
+	}
+
+	struct {
+		char *name;
+		uint32_t key;
+		struct foo val;
+	} tests[] = {
+		{ "relocate .rodata reference", 0, { 42, 0xfefeefef, 0x1111111111111111ULL, } },
+		{ "relocate .bss reference",    1, { } },
+		{ "relocate .rodata reference", 2, { } },
+		{ "relocate .data reference",   3, { 41, 0xeeeeefef, 0x2111111111111111ULL, } },
+	};
+
+	for (i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+		err = bpf_map_lookup_elem(map_fd, &tests[i].key, &val);
+		CHECK(err || memcmp(&val, &tests[i].val, sizeof(val)),
+		      tests[i].name, "err %d result { %u, %u, %llu } expected { %u, %u, %llu }\n",
+		      err, val.a, val.b, val.c, tests[i].val.a, tests[i].val.b, tests[i].val.c);
+	}
+}
+
+static void test_global_data_rdonly(struct bpf_object *obj, __u32 duration)
+{
+	int err = -ENOMEM, map_fd, zero = 0;
+	struct bpf_map *map;
+	__u8 *buff;
+
+	map = bpf_object__find_map_by_name(obj, "test_glo.rodata");
+	if (!map || !bpf_map__is_internal(map)) {
+		error_cnt++;
+		return;
+	}
+
+	map_fd = bpf_map__fd(map);
+	if (map_fd < 0) {
+		error_cnt++;
+		return;
+	}
+
+	buff = malloc(bpf_map__def(map)->value_size);
+	if (buff)
+		err = bpf_map_update_elem(map_fd, &zero, buff, 0);
+	free(buff);
+	CHECK(!err || errno != EPERM, "test .rodata read-only map",
+	      "err %d errno %d\n", err, errno);
+}
+
+void test_global_data(void)
+{
+	const char *file = "./test_global_data.o";
+	__u32 duration = 0, retval;
+	struct bpf_object *obj;
+	int err, prog_fd;
+
+	err = bpf_prog_load(file, BPF_PROG_TYPE_SCHED_CLS, &obj, &prog_fd);
+	if (CHECK(err, "load program", "error %d loading %s\n", err, file))
+		return;
+
+	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
+				NULL, NULL, &retval, &duration);
+	CHECK(err || retval, "pass global data run",
+	      "err %d errno %d retval %d duration %d\n",
+	      err, errno, retval, duration);
+
+	test_global_data_number(obj, duration);
+	test_global_data_string(obj, duration);
+	test_global_data_struct(obj, duration);
+	test_global_data_rdonly(obj, duration);
+
+	bpf_object__close(obj);
+}