004fb7809c
PR ld/10433 * elf-ifunc.c (_bfd_elf_allocate_ifunc_dyn_relocs): Set got to htab->init_got_offset and plt to htab->init_plt_offset when discarding space for dynamic relocations.
289 lines
8.5 KiB
C
289 lines
8.5 KiB
C
/* ELF STT_GNU_IFUNC support.
|
|
Copyright 2009
|
|
Free Software Foundation, Inc.
|
|
|
|
This file is part of BFD, the Binary File Descriptor library.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
|
|
MA 02110-1301, USA. */
|
|
|
|
#include "sysdep.h"
|
|
#include "bfd.h"
|
|
#include "bfdlink.h"
|
|
#include "libbfd.h"
|
|
#define ARCH_SIZE 0
|
|
#include "elf-bfd.h"
|
|
#include "safe-ctype.h"
|
|
#include "libiberty.h"
|
|
#include "objalloc.h"
|
|
|
|
/* Create sections needed by STT_GNU_IFUNC symbol. */
|
|
|
|
bfd_boolean
|
|
_bfd_elf_create_ifunc_sections (bfd *abfd, struct bfd_link_info *info)
|
|
{
|
|
flagword flags, pltflags;
|
|
asection *s;
|
|
const struct elf_backend_data *bed = get_elf_backend_data (abfd);
|
|
struct elf_link_hash_table *htab = elf_hash_table (info);
|
|
|
|
if (htab->irelifunc != NULL || htab->iplt != NULL)
|
|
return TRUE;
|
|
|
|
flags = bed->dynamic_sec_flags;
|
|
pltflags = flags;
|
|
if (bed->plt_not_loaded)
|
|
/* We do not clear SEC_ALLOC here because we still want the OS to
|
|
allocate space for the section; it's just that there's nothing
|
|
to read in from the object file. */
|
|
pltflags &= ~ (SEC_CODE | SEC_LOAD | SEC_HAS_CONTENTS);
|
|
else
|
|
pltflags |= SEC_ALLOC | SEC_CODE | SEC_LOAD;
|
|
if (bed->plt_readonly)
|
|
pltflags |= SEC_READONLY;
|
|
|
|
if (info->shared)
|
|
{
|
|
/* We need to create .rel[a].ifunc for shared objects. */
|
|
const char *rel_sec = (bed->rela_plts_and_copies_p
|
|
? ".rela.ifunc" : ".rel.ifunc");
|
|
|
|
s = bfd_make_section_with_flags (abfd, rel_sec,
|
|
flags | SEC_READONLY);
|
|
if (s == NULL
|
|
|| ! bfd_set_section_alignment (abfd, s,
|
|
bed->s->log_file_align))
|
|
return FALSE;
|
|
htab->irelifunc = s;
|
|
}
|
|
else
|
|
{
|
|
/* We need to create .iplt, .rel[a].iplt, .igot and .igot.plt
|
|
for static executables. */
|
|
s = bfd_make_section_with_flags (abfd, ".iplt", pltflags);
|
|
if (s == NULL
|
|
|| ! bfd_set_section_alignment (abfd, s, bed->plt_alignment))
|
|
return FALSE;
|
|
htab->iplt = s;
|
|
|
|
s = bfd_make_section_with_flags (abfd,
|
|
(bed->rela_plts_and_copies_p
|
|
? ".rela.iplt" : ".rel.iplt"),
|
|
flags | SEC_READONLY);
|
|
if (s == NULL
|
|
|| ! bfd_set_section_alignment (abfd, s,
|
|
bed->s->log_file_align))
|
|
return FALSE;
|
|
htab->irelplt = s;
|
|
|
|
/* We don't need the .igot section if we have the .igot.plt
|
|
section. */
|
|
if (bed->want_got_plt)
|
|
s = bfd_make_section_with_flags (abfd, ".igot.plt", flags);
|
|
else
|
|
s = bfd_make_section_with_flags (abfd, ".igot", flags);
|
|
if (s == NULL
|
|
|| !bfd_set_section_alignment (abfd, s,
|
|
bed->s->log_file_align))
|
|
return FALSE;
|
|
htab->igotplt = s;
|
|
}
|
|
|
|
return TRUE;
|
|
}
|
|
|
|
/* For a STT_GNU_IFUNC symbol, create a dynamic reloc section, SRELOC,
|
|
for the input section, SEC, and append this reloc to HEAD. */
|
|
|
|
asection *
|
|
_bfd_elf_create_ifunc_dyn_reloc (bfd *abfd, struct bfd_link_info *info,
|
|
asection *sec, asection *sreloc,
|
|
struct elf_dyn_relocs **head)
|
|
{
|
|
struct elf_dyn_relocs *p;
|
|
struct elf_link_hash_table *htab = elf_hash_table (info);
|
|
|
|
if (sreloc == NULL)
|
|
{
|
|
const struct elf_backend_data *bed = get_elf_backend_data (abfd);
|
|
|
|
if (htab->dynobj == NULL)
|
|
htab->dynobj = abfd;
|
|
|
|
sreloc = _bfd_elf_make_dynamic_reloc_section (sec, htab->dynobj,
|
|
bed->s->log_file_align,
|
|
abfd,
|
|
bed->rela_plts_and_copies_p);
|
|
if (sreloc == NULL)
|
|
return NULL;
|
|
}
|
|
|
|
p = *head;
|
|
if (p == NULL || p->sec != sec)
|
|
{
|
|
bfd_size_type amt = sizeof *p;
|
|
|
|
p = ((struct elf_dyn_relocs *) bfd_alloc (htab->dynobj, amt));
|
|
if (p == NULL)
|
|
return NULL;
|
|
p->next = *head;
|
|
*head = p;
|
|
p->sec = sec;
|
|
p->count = 0;
|
|
p->pc_count = 0;
|
|
}
|
|
p->count += 1;
|
|
|
|
return sreloc;
|
|
}
|
|
|
|
/* Allocate space in .plt, .got and associated reloc sections for
|
|
dynamic relocs against a STT_GNU_IFUNC symbol definition. */
|
|
|
|
bfd_boolean
|
|
_bfd_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
|
|
struct elf_link_hash_entry *h,
|
|
struct elf_dyn_relocs **head,
|
|
unsigned int plt_entry_size,
|
|
unsigned int got_entry_size)
|
|
{
|
|
asection *plt, *gotplt, *relplt;
|
|
struct elf_dyn_relocs *p;
|
|
unsigned int sizeof_reloc;
|
|
const struct elf_backend_data *bed;
|
|
struct elf_link_hash_table *htab;
|
|
|
|
/* When a shared library references a STT_GNU_IFUNC symbol defined
|
|
in executable, the address of the resolved function may be used.
|
|
But in non-shared executable, the address of its .plt slot may
|
|
be used. Pointer equality may not work correctly. PIE should
|
|
be used if pointer equality is required here. */
|
|
if (!info->shared
|
|
&& (h->dynindx != -1
|
|
|| info->export_dynamic)
|
|
&& h->pointer_equality_needed)
|
|
{
|
|
info->callbacks->einfo
|
|
(_("%F%P: dynamic STT_GNU_IFUNC symbol `%s' with pointer "
|
|
"equality in `%B' can not be used when making an "
|
|
"executable; recompile with -fPIE and relink with -pie\n"),
|
|
h->root.root.string,
|
|
h->root.u.def.section->owner);
|
|
bfd_set_error (bfd_error_bad_value);
|
|
return FALSE;
|
|
}
|
|
|
|
htab = elf_hash_table (info);
|
|
|
|
/* Return and discard space for dynamic relocations against it if
|
|
it is never referenced in a non-shared object. */
|
|
if (!h->ref_regular)
|
|
{
|
|
if (h->plt.refcount > 0
|
|
|| h->got.refcount > 0)
|
|
abort ();
|
|
h->got = htab->init_got_offset;
|
|
h->plt = htab->init_plt_offset;
|
|
*head = NULL;
|
|
return TRUE;
|
|
}
|
|
|
|
bed = get_elf_backend_data (info->output_bfd);
|
|
if (bed->rela_plts_and_copies_p)
|
|
sizeof_reloc = bed->s->sizeof_rela;
|
|
else
|
|
sizeof_reloc = bed->s->sizeof_rel;
|
|
|
|
/* When building a static executable, use .iplt, .igot.plt and
|
|
.rel[a].iplt sections for STT_GNU_IFUNC symbols. */
|
|
if (htab->splt != NULL)
|
|
{
|
|
plt = htab->splt;
|
|
gotplt = htab->sgotplt;
|
|
relplt = htab->srelplt;
|
|
|
|
/* If this is the first .plt entry, make room for the special
|
|
first entry. */
|
|
if (plt->size == 0)
|
|
plt->size += plt_entry_size;
|
|
}
|
|
else
|
|
{
|
|
plt = htab->iplt;
|
|
gotplt = htab->igotplt;
|
|
relplt = htab->irelplt;
|
|
}
|
|
|
|
/* Don't update value of STT_GNU_IFUNC symbol to PLT. We need
|
|
the original value for R_*_IRELATIVE. */
|
|
h->plt.offset = plt->size;
|
|
|
|
/* Make room for this entry in the .plt/.iplt section. */
|
|
plt->size += plt_entry_size;
|
|
|
|
/* We also need to make an entry in the .got.plt/.got.iplt section,
|
|
which will be placed in the .got section by the linker script. */
|
|
gotplt->size += got_entry_size;
|
|
|
|
/* We also need to make an entry in the .rel[a].plt/.rel[a].iplt
|
|
section. */
|
|
relplt->size += sizeof_reloc;
|
|
relplt->reloc_count++;
|
|
|
|
/* We need dynamic relocation for STT_GNU_IFUNC symbol only when
|
|
there is a non-GOT reference in a shared object. */
|
|
if (!info->shared
|
|
|| !h->non_got_ref)
|
|
*head = NULL;
|
|
|
|
/* Finally, allocate space. */
|
|
for (p = *head; p != NULL; p = p->next)
|
|
htab->irelifunc->size += p->count * sizeof_reloc;
|
|
|
|
/* For STT_GNU_IFUNC symbol, .got.plt has the real function addres
|
|
and .got has the PLT entry adddress. We will load the GOT entry
|
|
with the PLT entry in finish_dynamic_symbol if it is used. For
|
|
branch, it uses .got.plt. For symbol value,
|
|
1. Use .got.plt in a shared object if it is forced local or not
|
|
dynamic.
|
|
2. Use .got.plt in a non-shared object if pointer equality isn't
|
|
needed.
|
|
3. Use .got.plt in PIE.
|
|
4. Use .got.plt if .got isn't used.
|
|
5. Otherwise use .got so that it can be shared among different
|
|
objects at run-time.
|
|
We only need to relocate .got entry in shared object. */
|
|
if ((info->shared
|
|
&& (h->dynindx == -1
|
|
|| h->forced_local))
|
|
|| (!info->shared
|
|
&& !h->pointer_equality_needed)
|
|
|| (info->executable && info->shared)
|
|
|| htab->sgot == NULL)
|
|
{
|
|
/* Use .got.plt. */
|
|
h->got.offset = (bfd_vma) -1;
|
|
}
|
|
else
|
|
{
|
|
h->got.offset = htab->sgot->size;
|
|
htab->sgot->size += got_entry_size;
|
|
if (info->shared)
|
|
htab->srelgot->size += sizeof_reloc;
|
|
}
|
|
|
|
return TRUE;
|
|
}
|