[PATCH 0/1] __libc_start_main() now uses auxv to obtain phdr's address [BZ #29864]

[Florian Weimer]

* Yago Gutiérrez:

> diff --git a/sysdeps/unix/sysv/linux/dl-parse_auxv.h b/sysdeps/unix/sysv/linux/dl-parse_auxv.h
> index bf9374371e..f1a964ec1d 100644
> --- a/sysdeps/unix/sysv/linux/dl-parse_auxv.h
> +++ b/sysdeps/unix/sysv/linux/dl-parse_auxv.h
> @@ -52,6 +52,9 @@ void _dl_parse_auxv (ElfW(auxv_t) *av, dl_parse_auxv_t auxv_values)
>    _dl_random = (void *) auxv_values[AT_RANDOM];
>    GLRO(dl_minsigstacksize) = auxv_values[AT_MINSIGSTKSZ];
>    GLRO(dl_sysinfo_dso) = (void *) auxv_values[AT_SYSINFO_EHDR];
> +#ifndef SHARED
> +  GL(dl_phdr) = (void*) auxv_values[AT_PHDR];
> +#endif
>  #ifdef NEED_DL_SYSINFO
>    if (GLRO(dl_sysinfo_dso) != NULL)
>      GLRO(dl_sysinfo) = auxv_values[AT_SYSINFO];

The dynamic linker calls _dl_parse_auxv via _dl_sysdep_parse_arguments.
This gives direct access to all auxv entries.  I wonder if we should
abolish _dl_aux_init and call _dl_parse_auxv here.  It shouldn't be
necessary to duplicate this data in _dl_main_map and separate variables
(see _dl_non_dynamic_init).

Can we assume that AT_PHDR and AT_PHNUM are always present on Linux?

Thanks,
Florian