Re: [PATCH bpf-next 3/3] selftests/bpf: Add tests for get_func_[arg|ret|arg_cnt] helpers

[Andrii Nakryiko <andriin@fb.com>]

On 12/4/21 6:07 AM, Jiri Olsa wrote:
> Adding tests for get_func_[arg|ret|arg_cnt] helpers.
> Using these helpers in fentry/fexit/fmod_ret programs.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>   .../bpf/prog_tests/get_func_args_test.c       |  38 ++++++
>   .../selftests/bpf/progs/get_func_args_test.c  | 112 ++++++++++++++++++
>   2 files changed, 150 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
>   create mode 100644 tools/testing/selftests/bpf/progs/get_func_args_test.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c b/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
> new file mode 100644
> index 000000000000..c24807ae4361
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
> @@ -0,0 +1,38 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <test_progs.h>
> +#include "get_func_args_test.skel.h"
> +
> +void test_get_func_args_test(void)
> +{
> +	struct get_func_args_test *skel = NULL;
> +	__u32 duration = 0, retval;
> +	int err, prog_fd;
> +
> +	skel = get_func_args_test__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "get_func_args_test__open_and_load"))
> +		return;
> +
> +	err = get_func_args_test__attach(skel);
> +	if (!ASSERT_OK(err, "get_func_args_test__attach"))
> +		goto cleanup;
> +
> +	prog_fd = bpf_program__fd(skel->progs.test1);
> +	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> +				NULL, NULL, &retval, &duration);
> +	ASSERT_OK(err, "test_run");
> +	ASSERT_EQ(retval, 0, "test_run");
> +
> +	prog_fd = bpf_program__fd(skel->progs.fmod_ret_test);
> +	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> +				NULL, NULL, &retval, &duration);
> +	ASSERT_OK(err, "test_run");
> +	ASSERT_EQ(retval, 1234, "test_run");


are the other two programs executed implicitly during one of those test 
runs? Can you please leave a small comment somewhere here if that's true?


> +
> +	ASSERT_EQ(skel->bss->test1_result, 1, "test1_result");
> +	ASSERT_EQ(skel->bss->test2_result, 1, "test2_result");
> +	ASSERT_EQ(skel->bss->test3_result, 1, "test3_result");
> +	ASSERT_EQ(skel->bss->test4_result, 1, "test4_result");
> +
> +cleanup:
> +	get_func_args_test__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/get_func_args_test.c b/tools/testing/selftests/bpf/progs/get_func_args_test.c
> new file mode 100644
> index 000000000000..0d0a67c849ae
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/get_func_args_test.c
> @@ -0,0 +1,112 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include <errno.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +__u64 test1_result = 0;
> +SEC("fentry/bpf_fentry_test1")
> +int BPF_PROG(test1)
> +{
> +	__u64 cnt = bpf_get_func_arg_cnt(ctx);
> +	__u64 a = 0, z = 0, ret = 0;
> +	__s64 err;
> +
> +	test1_result = cnt == 1;
> +
> +	/* valid arguments */
> +	err = bpf_get_func_arg(ctx, 0, &a);
> +	test1_result &= err == 0 && (int) a == 1;


int cast unnecessary? but some ()'s wouldn't hurt...


> +
> +	/* not valid argument */
> +	err = bpf_get_func_arg(ctx, 1, &z);
> +	test1_result &= err == -EINVAL;
> +
> +	/* return value fails in fentry */
> +	err = bpf_get_func_ret(ctx, &ret);
> +	test1_result &= err == -EINVAL;
> +	return 0;
> +}
> +
> +__u64 test2_result = 0;
> +SEC("fexit/bpf_fentry_test2")
> +int BPF_PROG(test2)
> +{
> +	__u64 cnt = bpf_get_func_arg_cnt(ctx);
> +	__u64 a = 0, b = 0, z = 0, ret = 0;
> +	__s64 err;
> +
> +	test2_result = cnt == 2;
> +
> +	/* valid arguments */
> +	err = bpf_get_func_arg(ctx, 0, &a);
> +	test2_result &= err == 0 && (int) a == 2;
> +
> +	err = bpf_get_func_arg(ctx, 1, &b);
> +	test2_result &= err == 0 && b == 3;
> +
> +	/* not valid argument */
> +	err = bpf_get_func_arg(ctx, 2, &z);
> +	test2_result &= err == -EINVAL;
> +
> +	/* return value */
> +	err = bpf_get_func_ret(ctx, &ret);
> +	test2_result &= err == 0 && ret == 5;
> +	return 0;
> +}
> +
> +__u64 test3_result = 0;
> +SEC("fmod_ret/bpf_modify_return_test")
> +int BPF_PROG(fmod_ret_test, int _a, int *_b, int _ret)
> +{
> +	__u64 cnt = bpf_get_func_arg_cnt(ctx);
> +	__u64 a = 0, b = 0, z = 0, ret = 0;
> +	__s64 err;
> +
> +	test3_result = cnt == 2;
> +
> +	/* valid arguments */
> +	err = bpf_get_func_arg(ctx, 0, &a);
> +	test3_result &= err == 0 && (int) a == 1;
> +
> +	err = bpf_get_func_arg(ctx, 1, &b);
> +	test3_result &= err == 0;


why no checking of b value here?


> +
> +	/* not valid argument */
> +	err = bpf_get_func_arg(ctx, 2, &z);
> +	test3_result &= err == -EINVAL;
> +
> +	/* return value */
> +	err = bpf_get_func_ret(ctx, &ret);
> +	test3_result &= err == 0 && ret == 0;
> +	return 1234;
> +}
> +
> +__u64 test4_result = 0;
> +SEC("fexit/bpf_modify_return_test")
> +int BPF_PROG(fexit_test, int _a, __u64 _b, int _ret)
> +{
> +	__u64 cnt = bpf_get_func_arg_cnt(ctx);
> +	__u64 a = 0, b = 0, z = 0, ret = 0;
> +	__s64 err;
> +
> +	test4_result = cnt == 2;
> +
> +	/* valid arguments */
> +	err = bpf_get_func_arg(ctx, 0, &a);
> +	test4_result &= err == 0 && (int) a == 1;
> +
> +	err = bpf_get_func_arg(ctx, 1, &b);
> +	test4_result &= err == 0;


same, for consistency, b should have been checked, no?


> +
> +	/* not valid argument */
> +	err = bpf_get_func_arg(ctx, 2, &z);
> +	test4_result &= err == -EINVAL;
> +
> +	/* return value */
> +	err = bpf_get_func_ret(ctx, &ret);
> +	test4_result &= err == 0 && ret == 1234;
> +	return 0;
> +}