Re: [PATCH bpf-next 2/4] bpf/selftests: introduce bptool test runner and a first test

Quentin Monnet
2026-01-15T11:37:36Z

2026-01-14 09:59 UTC+0100 ~ "Alexis Lothoré (eBPF Foundation)"
<alexis.lothore@bootlin.com>
> The tools/testing/selftests/bpf directory contains multiple scripts
> (shell, python, c code, etc) that aim to test some specific features
> from bpftool. Those isolated tests are currently not executed by any CI
> automation. Create a dedicated runner for any bpftool-related test that
> can then be added to the list of executed runners in bpf CI automation.
> This new runner (and the corresponding Makefile tooling) is highly
> inspired from test_progs, but kept a bit simpler. This version supports
> the following features:
>
> - autodetection of bpftool test stored in the in bpftool_tests

(Typo: "in the in")

> directory
> - bpftool binary under test is passed as runner argument
> - a few helpers to allow to easily run abpftool commands while possibly

(Typo: abpftool)

> collecting the output
> - usage of assert macros shared with test_progs
> - basic sub-tests management
> - logs collection, logs being dumped only for failed tests
> - exit code reflecting whether all tests have passed or not
>
> As this runner needs at least one test to be implemented to properly
> compile, also bring bpftool_metadata, which is the conversion of
> test_bpftool_metadata.sh: this test validates that the output of some
> basic prog/map listings done with bpftool properly returns the metadata
> collected from the .rodata section of eBPF programs.
>
> This new runner gives an output similar to the one generated by
> test_progs:
>
> #2/1 metadata/metadata_unused: OK
> #2/2 metadata/metadata_used: OK
> #2 metadata: OK
> Summary: 1 PASSED, 0 FAILED
>
> Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>

Thanks a lot for this! It looks good, I only have a few minor comments.

> ---
> tools/testing/selftests/bpf/.gitignore | 1 +
> tools/testing/selftests/bpf/Makefile | 14 ++-
> tools/testing/selftests/bpf/bpftool_helpers.c | 114 ++++++++++++++++++
> tools/testing/selftests/bpf/bpftool_helpers.h | 19 +++
> .../testing/selftests/bpf/bpftool_tests/.gitignore | 2 +
> .../selftests/bpf/bpftool_tests/bpftool_metadata.c | 128 +++++++++++++++++++++
> tools/testing/selftests/bpf/test_bpftool.c | 126 ++++++++++++++++++++
> tools/testing/selftests/bpf/test_bpftool.h | 36 ++++++
> 8 files changed, 439 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
> index b8bf51b7a0b0..9498cc11de97 100644
> --- a/tools/testing/selftests/bpf/.gitignore
> +++ b/tools/testing/selftests/bpf/.gitignore
> @@ -2,6 +2,7 @@
> bpftool
> bpf-helpers*
> bpf-syscall*
> +test_bpftool
> test_verifier
> test_maps
> test_lru_map
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index fd42b7193d4e..a1fe94efa53c 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -76,7 +76,8 @@ endif
> TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_progs \
> test_sockmap \
> test_tcpnotify_user \
> - test_progs-no_alu32
> + test_progs-no_alu32 \
> + test_bpftool
> TEST_INST_SUBDIRS := no_alu32
>
> # Also test bpf-gcc, if present
> @@ -791,6 +792,17 @@ TRUNNER_BPF_BUILD_RULE := $$(error no BPF objects should be built)
> TRUNNER_BPF_CFLAGS :=
> $(eval $(call DEFINE_TEST_RUNNER,test_maps))
>
> +# Define bpftool test runner.
> +TRUNNER_TESTS_DIR := bpftool_tests
> +TRUNNER_BPF_PROGS_DIR := progs
> +TRUNNER_EXTRA_SOURCES := test_bpftool.c \
> + bpftool_helpers.c
> +TRUNNER_LIB_SOURCES :=
> +TRUNNER_EXTRA_FILES :=
> +TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
> +TRUNNER_BPF_CFLAGS :=
> +$(eval $(call DEFINE_TEST_RUNNER,test_bpftool))
> +
> # Define test_verifier test runner.
> # It is much simpler than test_maps/test_progs and sufficiently different from
> # them (e.g., test.h is using completely pattern), that it's worth just
> diff --git a/tools/testing/selftests/bpf/bpftool_helpers.c b/tools/testing/selftests/bpf/bpftool_helpers.c
> new file mode 100644
> index 000000000000..ff8084d9a121
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/bpftool_helpers.c
> @@ -0,0 +1,114 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include "bpftool_helpers.h"
> +#include "test_bpftool.h"
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <stdbool.h>
> +
> +#define BPFTOOL_PATH "./tools/sbin/bpftool"
> +#define BPFTOOL_CMD_MAX_LEN 256
> +
> +static int run_command(char *command, bool get_output, char *output_buf, size_t output_max_len)
> +{
> + FILE *f;
> + int ret;
> +
> + f = popen(command, "r");
> + if (!f)
> + return 1;
> +
> + if (get_output)
> + fread(output_buf, 1, output_max_len, f);
> + ret = pclose(f);
> +
> + return ret;
> +}
> +
> +int run_bpftool_command(char *args)
> +{
> + char cmd[BPFTOOL_CMD_MAX_LEN];
> + int ret;
> +
> + ret = snprintf(cmd, BPFTOOL_CMD_MAX_LEN, "%s %s > /dev/null 2>&1",
> + env.bpftool_path, args);
> + if (ret !=
> + strlen(env.bpftool_path) + 1 + strlen(args) + strlen(" > /dev/null 2>&1")) {
> + fprintf(stderr, "Failed to generate bpftool command\n");
> + return 1;
> + }
> +
> + return run_command(cmd, false, NULL, 0);
> +}
> +
> +int get_bpftool_command_output(char *args, char *output_buf, size_t output_max_len)
> +{
> + int ret;
> + char cmd[BPFTOOL_CMD_MAX_LEN];
> +
> + ret = snprintf(cmd, BPFTOOL_CMD_MAX_LEN, "%s %s", env.bpftool_path,
> + args);
> + if (ret != strlen(args) + strlen(env.bpftool_path) + 1) {
> + fprintf(stderr, "Failed to generate bpftool command");
> + return 1;
> + }
> +
> + return run_command(cmd, true, output_buf, output_max_len);
> +}
> +
> +void hijack_stdio(void)
> +{
> + fflush(stdout);
> + fflush(stderr);
> + if (env.current_subtest) {
> + env.current_test->saved_stdout = stdout;
> + env.current_test->saved_stderr = stderr;
> + stdout = open_memstream(&env.current_subtest->log,
> + &env.current_subtest->log_size);

Missing check on open_memstream() return value? Same below.

> +

Nit: blank line

> + } else {
> + env.saved_stdout = stdout;
> + env.saved_stderr = stderr;
> + stdout = open_memstream(&env.current_test->log,
> + &env.current_test->log_size);
> + }
> + stderr = stdout;
> +}
> +
> +void restore_stdio(void)
> +{
> + fclose(stdout);
> + if (env.current_subtest) {
> + stdout = env.current_test->saved_stdout;
> + stderr = env.current_test->saved_stderr;
> +

Nit: blank line

> + } else {
> + stdout = env.saved_stdout;
> + stderr = env.saved_stderr;
> + }
> +

Nit: blank line again

> +}
> +
> +void test__start_subtest(const char *subtest_name)
> +{
> + test__end_subtest();
> + env.current_test->subtests_count++;
> + env.subtest_states = realloc(env.subtest_states,
> + env.current_test->subtests_count *
> + sizeof(struct subtest_state));

Missing check on realloc()'s return value?

> + env.current_subtest =
> + &env.subtest_states[env.current_test->subtests_count - 1];
> + memset(env.current_subtest, 0, sizeof(struct subtest_state));
> + env.current_subtest->name = strdup(subtest_name);
> +
> + hijack_stdio();
> +}
> +
> +void test__end_subtest(void)
> +{
> + if (env.current_subtest) {
> + restore_stdio();
> + env.current_subtest = NULL;
> + }
> +}
> +
> diff --git a/tools/testing/selftests/bpf/bpftool_helpers.h b/tools/testing/selftests/bpf/bpftool_helpers.h
> new file mode 100644
> index 000000000000..1eacec7936ba
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/bpftool_helpers.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#pragma once
> +
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <stdbool.h>
> +
> +#define MAX_BPFTOOL_CMD_LEN (256)
> +
> +#ifndef ARRAY_SIZE
> +#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
> +#endif
> +
> +int run_bpftool_command(char *args);
> +int get_bpftool_command_output(char *args, char *output_buf, size_t output_max_len);
> +void test__start_subtest(const char *subtests_name);
> +void test__end_subtest(void);
> +void hijack_stdio(void);
> +void restore_stdio(void);
> diff --git a/tools/testing/selftests/bpf/bpftool_tests/.gitignore b/tools/testing/selftests/bpf/bpftool_tests/.gitignore
> new file mode 100644
> index 000000000000..89c4a3d37544
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/bpftool_tests/.gitignore
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +tests.h
> diff --git a/tools/testing/selftests/bpf/bpftool_tests/bpftool_metadata.c b/tools/testing/selftests/bpf/bpftool_tests/bpftool_metadata.c
> new file mode 100644
> index 000000000000..e7146b26f298
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/bpftool_tests/bpftool_metadata.c
> @@ -0,0 +1,128 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <bpftool_helpers.h>
> +#include <test_bpftool.h>
> +#include <assert_helpers.h>
> +#include <linux/bpf.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <fcntl.h>
> +#include <sys/stat.h>
> +#include <stdbool.h>
> +
> +#define BPFFS_DIR "/sys/fs/bpf/test_metadata"
> +#define BPFFS_USED BPFFS_DIR "/used"
> +#define BPFFS_UNUSED BPFFS_DIR "/unused"
> +
> +#define BPF_FILE_USED "metadata_used.bpf.o"
> +#define BPF_FILE_UNUSED "metadata_unused.bpf.o"
> +
> +#define MAX_BPFTOOL_OUTPUT_LEN (100*1000)

Maybe a power of 2 instead, 64k?

> +
> +#define MAX_TOKENS_TO_CHECK 3
> +static char output[MAX_BPFTOOL_OUTPUT_LEN];
> +
> +struct test_desc {
> + char *name;
> + char *bpf_prog;
> + char *bpffs_path;
> + char *expected_output[MAX_TOKENS_TO_CHECK];
> + char *expected_output_json[MAX_TOKENS_TO_CHECK];
> +};
> +
> +static int setup(struct test_desc *test)
> +{
> + return mkdir(BPFFS_DIR, 0700);
> +}
> +
> +static void cleanup(struct test_desc *test)
> +{
> + unlink(test->bpffs_path);
> + rmdir(BPFFS_DIR);
> +}
> +
> +static int check_metadata(char *buf, char * const *tokens, int count)
> +{
> + int i;
> +
> + for (i = 0; i < count && tokens[i]; i++)
> + if (!strstr(buf, tokens[i]))
> + return 1;
> +
> + return 0;
> +}
> +
> +static void run_test(struct test_desc *test)
> +{
> + int ret;
> + char cmd[MAX_BPFTOOL_CMD_LEN];
> +
> + snprintf(cmd, MAX_BPFTOOL_CMD_LEN, "prog load %s %s",
> + test->bpf_prog, test->bpffs_path);
> + ret = run_bpftool_command(cmd);
> + if (!ASSERT_OK(ret, "load program"))
> + return;
> +
> + /* Check output with default format */
> + ret = get_bpftool_command_output("prog show name prog", output,

I'd probably use "pinned" + pinned path rather than "name prog",
especially because the name for the program does not otherwise appear in
this file (and same below).

> + MAX_BPFTOOL_OUTPUT_LEN);
> + if (ASSERT_OK(ret, "get program info")) {
> + ret = check_metadata(output, test->expected_output,
> + ARRAY_SIZE(test->expected_output));
> + ASSERT_OK(ret, "find metadata");
> + }
> +
> + /* Check output with json format */
> + ret = get_bpftool_command_output("prog -j show name prog", output,
> + MAX_BPFTOOL_OUTPUT_LEN);
> + if (ASSERT_OK(ret, "get program info in json")) {
> + ret = check_metadata(output, test->expected_output_json,
> + ARRAY_SIZE(test->expected_output_json));
> + ASSERT_OK(ret, "find metadata in json");
> + }
> +

Nit: blank line

> +}
> +
> +struct test_desc tests[] = {
> + {
> + .name = "metadata_unused",
> + .bpf_prog = BPF_FILE_UNUSED,
> + .bpffs_path = BPFFS_UNUSED,
> + .expected_output = {
> + "a = \"foo\"",
> + "b = 1"
> + },
> + .expected_output_json = {
> + "\"metadata\":{\"a\":\"foo\",\"b\":1}"
> + }
> + },
> + {
> + .name = "metadata_used",
> + .bpf_prog = BPF_FILE_USED,
> + .bpffs_path = BPFFS_USED,
> + .expected_output = {
> + "a = \"bar\"",
> + "b = 2"
> + },
> + .expected_output_json = {
> + "\"metadata\":{\"a\":\"bar\",\"b\":2}"
> + }
> + }
> +};
> +
> +static const int tests_count = ARRAY_SIZE(tests);
> +
> +void test_metadata(void)
> +{
> + int i, ret;
> +
> + for (i = 0; i < tests_count; i++) {
> + test__start_subtest(tests[i].name);
> + ret = setup(&tests[i]);
> + if (!ASSERT_OK(ret, "setup bpffs pin dir"))
> + continue;
> + run_test(&tests[i]);
> + cleanup(&tests[i]);
> + }
> +

Nit: blank line

> +}
> +
> diff --git a/tools/testing/selftests/bpf/test_bpftool.c b/tools/testing/selftests/bpf/test_bpftool.c
> new file mode 100644
> index 000000000000..b5fb17d5ea2d
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_bpftool.c
> @@ -0,0 +1,126 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <test_bpftool.h>
> +#include <bpftool_helpers.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdbool.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +struct bpftool_runner_env env = {0};
> +
> +#define DEFINE_TEST(name) extern void test_##name(void);
> +#include <bpftool_tests/tests.h>
> +#undef DEFINE_TEST
> +
> +struct prog_test_def {
> + char *test_name;
> + void (*run_test)(void);
> +};
> +
> +static struct prog_test_def prog_test_defs[] = {
> +#define DEFINE_TEST(name) { \
> + .test_name = #name, \
> + .run_test = &test_##name, \
> +},
> +#include <bpftool_tests/tests.h>
> +#undef DEFINE_TEST
> +};
> +
> +
> +static const int tests_count = ARRAY_SIZE(prog_test_defs);
> +
> +/* Needed method for the assert macros exposed by assert_helpers.h */
> +void test__fail(void)
> +{
> + if (env.current_subtest)
> + env.current_subtest->failed = true;
> + if (!env.current_test->failed)
> + env.failure_cnt++;
> + env.current_test->failed = true;
> +}
> +
> +static void test_setup(struct test_state *test, char *name)
> +{
> + env.current_test = test;
> + env.current_test->name = strdup(name);
> +}
> +
> +static void dump_results(struct test_state *test, int test_index)

Would you mind renaming this function? It also frees the logs and names
and subtests states. Maybe "dump_results_and_cleanup"? Or move the all
the clean-up to test_teardown(). Even if we loop again over the
subtests, the overhead should be minimal, and I'd find it easier to follow.

> +{
> + int j;

Let's use "i" rather than "j"

> +
> + if (test->failed)
> + fprintf(stdout, "%s\n", test->log);
> + free(test->log);
> + for (j = 0; j < test->subtests_count; j++) {
> + if (env.subtest_states[j].failed)
> + fprintf(stdout, "%s\n", env.subtest_states[j].log);
> + free(env.subtest_states[j].log);
> + fprintf(stdout, "#%d/%d\t%s/%s: %s\n", test_index+1, j+1,
> + env.current_test->name,
> + env.subtest_states[j].name,
> + env.subtest_states[j].failed ? "KO" : "OK");
> + free(env.subtest_states[j].name);
> + }
> + if (env.current_test->subtests_count) {
> + free(env.subtest_states);
> + env.subtest_states = NULL;
> + }
> + fprintf(stdout, "#%d\t%s: %s\n", test_index + 1, test->name,
> + test->failed ? "KO" : "OK");
> +}
> +
> +static void test_teardown(struct test_state *test, int test_index)
> +{
> + dump_results(test, test_index);
> + free(env.current_test->name);
> + env.current_test = NULL;
> +}
> +
> +static int parse_args(int argc, char *argv[])
> +{
> + if (argc != 2)
> + return 1;
> + if (access(argv[1], R_OK|X_OK))
> + return 1;
> + env.bpftool_path = argv[1];
> +
> + return 0;
> +}
> +
> +static void usage(char *prog)
> +{
> + fprintf(stdout, "Usage: %s <bpftool_path>\n", prog);
> + fprintf(stdout, "\t<bpftool_path>: path to the bpftool binary to test\n");
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + struct test_state *ctx = NULL;
> + int i;
> +
> + if (parse_args(argc, argv)) {
> + fprintf(stderr, "Invalid arguments\n");
> + usage(argv[0]);
> + exit(EXIT_FAILURE);
> + }
> +
> + ctx = calloc(tests_count, sizeof(struct test_state));
> + if (!ctx)
> + exit(EXIT_FAILURE);
> +
> + for (i = 0; i < tests_count; i++) {
> + test_setup(&ctx[i], prog_test_defs[i].test_name);
> + hijack_stdio();

Nit: Move hijack_stdio()/restore_stdio() to test_setup()/test_teardown()?

> + prog_test_defs[i].run_test();
> + test__end_subtest();
> + restore_stdio();
> + test_teardown(&ctx[i], i);
> + }
> +
> + fprintf(stdout, "Summary: %d PASSED, %d FAILED\n",
> + tests_count - env.failure_cnt, env.failure_cnt);
> + free(ctx);
> + return env.failure_cnt ? EXIT_FAILURE : EXIT_SUCCESS;
> +}
> diff --git a/tools/testing/selftests/bpf/test_bpftool.h b/tools/testing/selftests/bpf/test_bpftool.h
> new file mode 100644
> index 000000000000..a78659eeaf2b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_bpftool.h
> @@ -0,0 +1,36 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#pragma once
> +
> +#include <stdio.h>
> +#include <stdbool.h>
> +
> +extern struct bpftool_runner_env env;
> +
> +void test__fail(void);
> +
> +struct test_state {
> + char *name;
> + char *log;
> + size_t log_size;
> + bool failed;
> + int subtests_count;
> + int subtests_failures;
> + FILE *saved_stdout;
> + FILE *saved_stderr;
> +};
> +
> +struct subtest_state {
> + char *name;
> + char *log;
> + size_t log_size;
> + bool failed;
> +};
> +struct bpftool_runner_env {
> + char *bpftool_path;
> + int failure_cnt;
> + FILE *saved_stdout;
> + FILE *saved_stderr;
> + struct test_state *current_test;
> + struct subtest_state *current_subtest;
> + struct subtest_state *subtest_states;
> +};
>