[1/3] elf: rtld_multiple_ref is always true

  For a long time, libc.so.6 has dependend on ld.so, which
means that there is a reference to ld.so in all processes,
and rtld_multiple_ref is always true.  In fact, if
rtld_multiple_ref were false, some of the ld.so setup code
would not run.
---
 elf/rtld.c | 104 +++++++++++++++++++++++++----------------------------
 1 file changed, 48 insertions(+), 56 deletions(-)
  

LGTM
Reviewed-by: DJ Delorie <dj@redhat.com>

Florian Weimer <fweimer@redhat.com> writes:
> diff --git a/elf/rtld.c b/elf/rtld.c

> -  bool rtld_multiple_ref = false;
> -  if (__glibc_likely (i < main_map->l_searchlist.r_nlist))
> -    {
> -      /* Some DT_NEEDED entry referred to the interpreter object itself, so
> -	 put it back in the list of visible objects.  We insert it into the
> -	 chain in symbol search order because gdb uses the chain's order as
> -	 its symbol search order.  */
> -      rtld_multiple_ref = true;

This takes out the rtld_multiple_ref logic, ok.

> -      GL(dl_rtld_map).l_prev = main_map->l_searchlist.r_list[i - 1];
> -      if (__glibc_likely (state.mode == rtld_mode_normal))
> -	{
> -	  GL(dl_rtld_map).l_next = (i + 1 < main_map->l_searchlist.r_nlist
> -				    ? main_map->l_searchlist.r_list[i + 1]
> -				    : NULL);

> +  /* Insert the link map for the dynamic loader into the chain in
> +     symbol search order because gdb uses the chain's order as its
> +     symbol search order.  */
> +  GL(dl_rtld_map).l_prev = main_map->l_searchlist.r_list[i - 1];
> +  if (__glibc_likely (state.mode == rtld_mode_normal))
> +    {
> +      GL(dl_rtld_map).l_next = (i + 1 < main_map->l_searchlist.r_nlist
> +				? main_map->l_searchlist.r_list[i + 1]
> +				: NULL);

Reindent, ok.

>  #ifdef NEED_DL_SYSINFO_DSO
> -	  if (GLRO(dl_sysinfo_map) != NULL
> -	      && GL(dl_rtld_map).l_prev->l_next == GLRO(dl_sysinfo_map)
> -	      && GL(dl_rtld_map).l_next != GLRO(dl_sysinfo_map))
> -	    GL(dl_rtld_map).l_prev = GLRO(dl_sysinfo_map);
> +      if (GLRO(dl_sysinfo_map) != NULL
> +	  && GL(dl_rtld_map).l_prev->l_next == GLRO(dl_sysinfo_map)
> +	  && GL(dl_rtld_map).l_next != GLRO(dl_sysinfo_map))
> +	GL(dl_rtld_map).l_prev = GLRO(dl_sysinfo_map);
>  #endif

Reindent, ok.

> -	}
> -      else
> -	/* In trace mode there might be an invisible object (which we
> -	   could not find) after the previous one in the search list.
> -	   In this case it doesn't matter much where we put the
> -	   interpreter object, so we just initialize the list pointer so
> -	   that the assertion below holds.  */
> -	GL(dl_rtld_map).l_next = GL(dl_rtld_map).l_prev->l_next;
> -
> -      assert (GL(dl_rtld_map).l_prev->l_next == GL(dl_rtld_map).l_next);
> -      GL(dl_rtld_map).l_prev->l_next = &GL(dl_rtld_map);
> -      if (GL(dl_rtld_map).l_next != NULL)
> -	{
> -	  assert (GL(dl_rtld_map).l_next->l_prev == GL(dl_rtld_map).l_prev);
> -	  GL(dl_rtld_map).l_next->l_prev = &GL(dl_rtld_map);
> -	}
> +    }
> +  else
> +    /* In trace mode there might be an invisible object (which we
> +       could not find) after the previous one in the search list.
> +       In this case it doesn't matter much where we put the
> +       interpreter object, so we just initialize the list pointer so
> +       that the assertion below holds.  */
> +    GL(dl_rtld_map).l_next = GL(dl_rtld_map).l_prev->l_next;
> +
> +  assert (GL(dl_rtld_map).l_prev->l_next == GL(dl_rtld_map).l_next);
> +  GL(dl_rtld_map).l_prev->l_next = &GL(dl_rtld_map);
> +  if (GL(dl_rtld_map).l_next != NULL)
> +    {
> +      assert (GL(dl_rtld_map).l_next->l_prev == GL(dl_rtld_map).l_prev);
> +      GL(dl_rtld_map).l_next->l_prev = &GL(dl_rtld_map);
>      }

Reindent, ok.


> -  if (rtld_multiple_ref)
> -    {
> -      /* There was an explicit ref to the dynamic linker as a shared lib.
> -	 Re-relocate ourselves with user-controlled symbol definitions.
> +  /* Re-relocate ourselves with user-controlled symbol definitions.

Reindent without conditional, ok.

> -	 We must do this after TLS initialization in case after this
> -	 re-relocation, we might call a user-supplied function
> -	 (e.g. calloc from _dl_relocate_object) that uses TLS data.  */
> +     We must do this after TLS initialization in case after this
> +     re-relocation, we might call a user-supplied function
> +     (e.g. calloc from _dl_relocate_object) that uses TLS data.  */

Reindent, ok.

> -      /* Set up the object lookup structures.  */
> -      _dl_find_object_init ();
> +  /* Set up the object lookup structures.  */
> +  _dl_find_object_init ();

Reindent, ok.

> -      /* The malloc implementation has been relocated, so resolving
> -	 its symbols (and potentially calling IFUNC resolvers) is safe
> -	 at this point.  */
> -      __rtld_malloc_init_real (main_map);
> +  /* The malloc implementation has been relocated, so resolving
> +     its symbols (and potentially calling IFUNC resolvers) is safe
> +     at this point.  */
> +  __rtld_malloc_init_real (main_map);

Reindent, ok.

> -      /* Likewise for the locking implementation.  */
> -      __rtld_mutex_init ();
> +  /* Likewise for the locking implementation.  */
> +  __rtld_mutex_init ();

Reindent, ok.

> -      RTLD_TIMING_VAR (start);
> -      rtld_timer_start (&start);
> +  {
> +    RTLD_TIMING_VAR (start);
> +    rtld_timer_start (&start);
>  
> -      /* Mark the link map as not yet relocated again.  */
> -      GL(dl_rtld_map).l_relocated = 0;
> -      _dl_relocate_object (&GL(dl_rtld_map), main_map->l_scope, 0, 0);
> +    /* Mark the link map as not yet relocated again.  */
> +    GL(dl_rtld_map).l_relocated = 0;
> +    _dl_relocate_object (&GL(dl_rtld_map), main_map->l_scope, 0, 0);
>  
> -      rtld_timer_accum (&relocate_time, start);
> -    }
> +    rtld_timer_accum (&relocate_time, start);
> +  }

Re-wrap in its own braces for scoping, ok.

>    /* Relocation is complete.  Perform early libc initialization.  This
>       is the initial libc, even if audit modules have been loaded with
>