[PATCH v2 bpf-next 04/12] selftests/bpf: add CO-RE relocs testing setup

Andrii Nakryiko
2019-07-30T19:54:51Z

Add CO-RE relocation test runner. Add one simple test validating that
libbpf's logic for searching for kernel image and loading BTF out of it
works.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
---
.../selftests/bpf/prog_tests/core_reloc.c | 125 ++++++++++++++++++
.../bpf/progs/test_core_reloc_kernel.c | 36 +++++
2 files changed, 161 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/core_reloc.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c

diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
new file mode 100644
index 000000000000..fab7492a8714
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+struct core_reloc_test_case {
+ const char *case_name;
+ const char *bpf_obj_file;
+ const char *btf_src_file;
+ const char *input;
+ int input_len;
+ const char *output;
+ int output_len;
+ bool fails;
+};
+
+static struct core_reloc_test_case test_cases[] = {
+ /* validate we can find kernel image and use its BTF for relocs */
+ {
+ .case_name = "kernel",
+ .bpf_obj_file = "test_core_reloc_kernel.o",
+ .btf_src_file = NULL, /* load from /lib/modules/$(uname -r) */
+ .input = "",
+ .input_len = 0,
+ .output = "\1", /* true */
+ .output_len = 1,
+ },
+};
+
+struct data {
+ char in[256];
+ char out[256];
+};
+
+void test_core_reloc(void)
+{
+ const char *probe_name = "raw_tracepoint/sys_enter";
+ struct bpf_object_load_attr load_attr = {};
+ struct core_reloc_test_case *test_case;
+ int err, duration = 0, i, equal;
+ struct bpf_link *link = NULL;
+ struct bpf_map *data_map;
+ struct bpf_program *prog;
+ struct bpf_object *obj;
+ const int zero = 0;
+ struct data data;
+
+ for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
+ test_case = &test_cases[i];
+
+ if (!test__start_subtest(test_case->case_name))
+ continue;
+
+ obj = bpf_object__open(test_case->bpf_obj_file);
+ if (CHECK(IS_ERR_OR_NULL(obj), "obj_open",
+ "failed to open '%s': %ld\n",
+ test_case->bpf_obj_file, PTR_ERR(obj)))
+ continue;
+
+ prog = bpf_object__find_program_by_title(obj, probe_name);
+ if (CHECK(!prog, "find_probe",
+ "prog '%s' not found\n", probe_name))
+ goto cleanup;
+ bpf_program__set_type(prog, BPF_PROG_TYPE_RAW_TRACEPOINT);
+
+ load_attr.obj = obj;
+ load_attr.log_level = 0;
+ load_attr.target_btf_path = test_case->btf_src_file;
+ err = bpf_object__load_xattr(&load_attr);
+ if (test_case->fails) {
+ CHECK(!err, "obj_load_fail",
+ "should fail to load prog '%s'\n", probe_name);
+ goto cleanup;
+ } else {
+ if (CHECK(err, "obj_load",
+ "failed to load prog '%s': %d\n",
+ probe_name, err))
+ goto cleanup;
+ }
+
+ link = bpf_program__attach_raw_tracepoint(prog, "sys_enter");
+ if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n",
+ PTR_ERR(link)))
+ goto cleanup;
+
+ data_map = bpf_object__find_map_by_name(obj, "test_cor.bss");
+ if (CHECK(!data_map, "find_data_map", "data map not found\n"))
+ goto cleanup;
+
+ memset(&data, 0, sizeof(data));
+ memcpy(data.in, test_case->input, test_case->input_len);
+
+ err = bpf_map_update_elem(bpf_map__fd(data_map),
+ &zero, &data, 0);
+ if (CHECK(err, "update_data_map",
+ "failed to update .data map: %d\n", err))
+ goto cleanup;
+
+ /* trigger test run */
+ usleep(1);
+
+ err = bpf_map_lookup_elem(bpf_map__fd(data_map), &zero, &data);
+ if (CHECK(err, "get_result",
+ "failed to get output data: %d\n", err))
+ goto cleanup;
+
+ equal = memcmp(data.out, test_case->output,
+ test_case->output_len) == 0;
+ if (CHECK(!equal, "check_result",
+ "input/output data don't match\n")) {
+ int j;
+
+ for (j = 0; j < test_case->output_len; j++) {
+ test__printf("byte #%d, EXP 0x%02hhx GOT 0x%02hhx\n",
+ j, test_case->output[j], data.out[j]);
+ }
+ goto cleanup;
+ }
+
+cleanup:
+ if (!IS_ERR_OR_NULL(link)) {
+ bpf_link__destroy(link);
+ link = NULL;
+ }
+ bpf_object__close(obj);
+ }
+}
diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
new file mode 100644
index 000000000000..37e02aa3f0c8
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+static volatile struct data {
+ char in[256];
+ char out[256];
+} data;
+
+struct task_struct {
+ int pid;
+ int tgid;
+};
+
+SEC("raw_tracepoint/sys_enter")
+int test_core_kernel(void *ctx)
+{
+ struct task_struct *task = (void *)bpf_get_current_task();
+ uint64_t pid_tgid = bpf_get_current_pid_tgid();
+ int pid, tgid;
+
+ if (BPF_CORE_READ(&pid, &task->pid) ||
+ BPF_CORE_READ(&tgid, &task->tgid))
+ return 1;
+
+ /* validate pid + tgid matches */
+ data.out[0] = (((uint64_t)pid << 32) | tgid) == pid_tgid;
+
+ return 0;
+}
+
--
2.17.1