On Fri, Aug 30, 2024 at 12:30 AM Tony Ambardar <tony.ambardar@xxxxxxxxx> wrote:
>
> Allow bpf_object__open() to access files of either endianness, and convert
> included BPF programs to native byte-order in-memory for introspection.
> Loading BPF objects of non-native byte-order is still disallowed however.
>
> Signed-off-by: Tony Ambardar <tony.ambardar@xxxxxxxxx>
> ---
> tools/lib/bpf/libbpf.c | 49 +++++++++++++++++++++++++++------
> tools/lib/bpf/libbpf_internal.h | 11 ++++++++
> 2 files changed, 52 insertions(+), 8 deletions(-)
>
[...]
>
> + /* Validate ELF object endianness... */
> + if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
> + ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
> + err = -LIBBPF_ERRNO__ENDIAN;
> + pr_warn("elf: '%s' has unknown byte order\n", obj->path);
> + goto errout;
> + }
> + /* and preserve outside lifetime of bpf_object_open() */
what does it mean "preserve outside lifetime" ?
> + obj->byteorder = ehdr->e_ident[EI_DATA];
> +
> +
> +
why so many empty lines?..
> if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) {
> pr_warn("elf: failed to get section names section index for %s: %s\n",
> obj->path, elf_errmsg(-1));
[...]
> err = bpf_object__elf_init(obj);
> - err = err ? : bpf_object__check_endianness(obj);
> err = err ? : bpf_object__elf_collect(obj);
> err = err ? : bpf_object__collect_externs(obj);
> err = err ? : bpf_object_fixup_btf(obj);
> @@ -8500,6 +8529,10 @@ static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const ch
>
> if (obj->gen_loader)
> bpf_gen__init(obj->gen_loader, extra_log_level, obj->nr_programs, obj->nr_maps);
nit: add {} around if, both sides should either have or not have {}
> + else if (!is_native_endianness(obj)) {
> + pr_warn("object '%s' is not native endianness\n", obj->name);
"object '%s': load is not supported in non-native endianness\n"
> + return libbpf_err(-LIBBPF_ERRNO__ENDIAN);
> + }
>
> err = bpf_object_prepare_token(obj);
> err = err ? : bpf_object__probe_loading(obj);
[...]
