On Fri, Aug 30, 2024 at 10:34 AM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> Create a BTF with endianness different from host, make a distilled
> base/split BTF pair from it, dump as raw bytes, import again and
> verify that endianness is preserved.
>
> Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
> ---
> .../selftests/bpf/prog_tests/btf_distill.c | 73 +++++++++++++++++++
> 1 file changed, 73 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/btf_distill.c b/tools/testing/selftests/bpf/prog_tests/btf_distill.c
> index bfbe795823a2..810b2e434562 100644
> --- a/tools/testing/selftests/bpf/prog_tests/btf_distill.c
> +++ b/tools/testing/selftests/bpf/prog_tests/btf_distill.c
> @@ -535,6 +535,77 @@ static void test_distilled_base_vmlinux(void)
> btf__free(vmlinux_btf);
> }
>
> +static bool is_host_big_endian(void)
> +{
> + return htons(0x1234) == 0x1234;
> +}
> +
> +/* Split and new base BTFs should inherit endianness from source BTF. */
> +static void test_distilled_endianness(void)
> +{
> + struct btf *base = NULL, *split = NULL, *new_base = NULL, *new_split = NULL;
> + struct btf *new_base1 = NULL, *new_split1 = NULL;
> + enum btf_endianness inverse_endianness;
> + const void *raw_data;
> + __u32 size;
> +
> + printf("is_host_big_endian? %d\n", is_host_big_endian());
removed printf
> + inverse_endianness = is_host_big_endian() ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN;
> + base = btf__new_empty();
> + btf__set_endianness(base, inverse_endianness);
> + if (!ASSERT_OK_PTR(base, "empty_main_btf"))
moved check before set_endianness
applied to bpf-next after Tony's endianness fix, thanks!
> + return;
> + btf__add_int(base, "int", 4, BTF_INT_SIGNED); /* [1] int */
> + VALIDATE_RAW_BTF(
> + base,
> + "[1] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED");
> + split = btf__new_empty_split(base);
> + if (!ASSERT_OK_PTR(split, "empty_split_btf"))
> + goto cleanup;
> + btf__add_ptr(split, 1);
[...]
