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xtensa: don't emit dynamic relocation for weak undefined symbol

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Resolved reference to a weak undefined symbol in PIE must not have
a dynamic relative relocation against itself, otherwise the value of a
reference will be changed from 0 to the base of executable, breaking
code like the following:

  void weak_function (void);
  if (weak_function)
    weak_function ();

This fixes tests for PR ld/22269 and a number of PIE tests in xtensa gcc
testsuite.

bfd/
2018-07-06  Max Filippov  <jcmvbkbc@gmail.com>

	* elf32-xtensa.c (elf_xtensa_allocate_dynrelocs): Don't allocate
	space for dynamic relocation for undefined weak symbol.
	(elf_xtensa_relocate_section): Don't emit R_XTENSA_RELATIVE
	relocation for undefined weak symbols.
	(shrink_dynamic_reloc_sections): Don't shrink dynamic relocation
	section for relocations against undefined weak symbols.
This commit is contained in:
Max Filippov 2018-07-02 11:12:44 -07:00
parent ad1cc4e492
commit c451bb34ae
2 changed files with 20 additions and 2 deletions
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9
bfd/ChangeLog
View File

@ -1,3 +1,12 @@
2018-07-06 Max Filippov <jcmvbkbc@gmail.com>
* elf32-xtensa.c (elf_xtensa_allocate_dynrelocs): Don't allocate
space for dynamic relocation for undefined weak symbol.
(elf_xtensa_relocate_section): Don't emit R_XTENSA_RELATIVE
relocation for undefined weak symbols.
(shrink_dynamic_reloc_sections): Don't shrink dynamic relocation
section for relocations against undefined weak symbols.
2018-07-06 Alan Hayward <alan.hayward@arm.com>
* elf.c (elfcore_grok_aarch_sve): New function.

13
bfd/elf32-xtensa.c
View File

@ -1437,6 +1437,10 @@ elf_xtensa_allocate_dynrelocs (struct elf_link_hash_entry *h, void *arg)
if (! elf_xtensa_dynamic_symbol_p (h, info))
elf_xtensa_make_sym_local (info, h);
if (! elf_xtensa_dynamic_symbol_p (h, info)
&& h->root.type == bfd_link_hash_undefweak)
return TRUE;
if (h->plt.refcount > 0)
htab->elf.srelplt->size += (h->plt.refcount * sizeof (Elf32_External_Rela));
@ -2777,12 +2781,16 @@ elf_xtensa_relocate_section (bfd *output_bfd,
}
unresolved_reloc = FALSE;
}
else
else if (!is_weak_undef)
{
/* Generate a RELATIVE relocation. */
outrel.r_info = ELF32_R_INFO (0, R_XTENSA_RELATIVE);
outrel.r_addend = 0;
}
else
{
continue;
}
}
loc = (srel->contents
@ -10013,7 +10021,8 @@ shrink_dynamic_reloc_sections (struct bfd_link_info *info,
if ((r_type == R_XTENSA_32 || r_type == R_XTENSA_PLT)
&& (input_section->flags & SEC_ALLOC) != 0
&& (dynamic_symbol || bfd_link_pic (info)))
&& (dynamic_symbol || bfd_link_pic (info))
&& (!h || h->root.type != bfd_link_hash_undefweak))
{
asection *srel;
bfd_boolean is_plt = FALSE;