A limitation on the new powerpc (32-bit) use of secure PLT instead of bss PLT?

[Mark Millard]

Looking around I ran into from a .../binutils-2_25_1/bfd/elf32-ppc.c :

	  /* Profiling of shared libs (and pies) is not supported with
	     secure plt, because ppc32 does profiling before a
	     function prologue and a secure plt pic call stubs needs
	     r30 to be set up.  */

A little more context for this in ppc_elf_select_plt_layout is:

  if (htab->plt_type == PLT_UNSET)
    {
      struct elf_link_hash_entry *h;
      if (htab->params->plt_style == PLT_OLD)
	htab->plt_type = PLT_OLD;
      else if (info->shared
	       && htab->elf.dynamic_sections_created
	       && (h = elf_link_hash_lookup (&htab->elf, "_mcount",
					     FALSE, FALSE, TRUE)) != NULL
	       && (h->type == STT_FUNC
		   || h->needs_plt)
	       && h->ref_regular
	       && !(SYMBOL_CALLS_LOCAL (info, h)
		    || (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT
			&& h->root.type == bfd_link_hash_undefweak)))
	{
	  /* Profiling of shared libs (and pies) is not supported with
	     secure plt, because ppc32 does profiling before a
	     function prologue and a secure plt pic call stubs needs
	     r30 to be set up.  */
	  htab->plt_type = PLT_OLD;
	}
      else
. . .



===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)