Re: [Elftoolchain-developers] arch specific sections

[Peng F. <van...@gm...>]

Hi Joseph Koshy,

Thanks. I find that elf_rawdata does not check the section type. I'll try
it.
Is it needed to add arch specific sections support to elf_getdata or the
arch specific sections should be handled using elf_rawdata by the caller ?
I am not sure about this.

Regards,
Peng


2013/7/1 Joseph Koshy <jk...@us...>

> Hello Peng Fan,
>
> > I am trying to use elftoolchain to handle arm elf object files.
> > But I always get error when handling ".ARM.attributes, .ARM.exidx ,
> > .ARM.extab " sections.
> >
> > I traced the source code and found that it fails at elf_data.c line 93.
> > The following is a piece of code.
> >
> > if ((elftype = _libelf_xlate_shtype(sh_type)) < ELF_T_FIRST ||
> >    elftype > ELF_T_LAST || (sh_type != SHT_NOBITS &&
> >    sh_offset + sh_size > (uint64_t) e->e_rawsize)) {
> > LIBELF_SET_ERROR(SECTION, 0);
> > return (NULL);
> > }
> > The .ARM.* sections are specific to ARM and the _libelf_xlate_shtype
> > function does not handle such
> > arch specific sections.
> >
> > I have a question about how to add support for arch specific sections,
> not
> > only to arm, but also other archs.
> >
> > I added the following code before invoke  _libelf_xlate_shtype  to handle
> > arm specific sections, but I am not
> >  sure whether this is the right way.
> >
> >   if (s->s_elf->e_u.e_elf.e_ehdr.e_ehdr32->e_machine == EM_ARM) {
> >     if ((sh_type == 0x70000003) || (sh_type == 0x70000001)) {
> >       if ((d = _libelf_allocate_data(s)) == NULL)
> >         return (NULL);
> >       d->d_buf = 0;
> >       d->d_size = 0;
> >       return (d);
> >     }
> >   }
> >    if ((elftype = _libelf_xlate_shtype(sh_type)) < ELF_T_FIRST ||
> >
> > Thanks very much.
>
> libelf doesn't know how to translate processor specific sections like the
> above.
>
> You could try the elf_rawdata() API, if you need access to the raw
> data in these sections.
>
> HTH,
> Joseph Koshy
>