On Tue, Nov 26, 2024 at 11:31 AM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> On Tue, 2024-11-26 at 11:26 -0800, Andrii Nakryiko wrote:
> > On Thu, Nov 21, 2024 at 11:02 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
> > >
> > > btf_encoder__tag_kfuncs() reads .BTF_ids section to identify a set of
> > > kfuncs present in the ELF being processed. This section consists of
> > > records of the following shape:
> > >
> > > struct btf_id_and_flag {
> > > uint32_t id;
> > > uint32_t flags;
> > > };
> > >
> >
> > Can we just set data->d_type to ELF_T_WORD and let libelf handle the byte swap?
>
> When I tried 'data->d_type = ELF_T_WORD' + gelf_xlatetom() snippet
> suggested by Tony Ambardar some time ago, I got a write protection error.
> Concluded that this is so, because file is opened in O_RDONLY mode.
Ok, maybe don't follow my words *exactly*, just in spirit ;) I see
there is elf_getdata_rawchunk() API in libelf, which seems useful:
/* Get data translated from a chunk of the file contents as section data
would be for TYPE. The resulting Elf_Data pointer is valid until
elf_end (ELF) is called. */
extern Elf_Data *elf_getdata_rawchunk (Elf *__elf,
int64_t __offset, size_t __size,
Elf_Type __type);
I don't know the surrounding code, I was just hoping to leverage
libelf's byte swapping support (which I think I learned from Tony as
well). But if it's too inconvenient, so be it.
>
> (Also please note v2 of this patch).
>
> [...]
>
