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Bring in 2 patches from binutils:

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From Alan Modra: Wed, 3 Jul 2013 11:51:56 +0930: powerpc64 call stubs:
    This brings powerpc64 ld in line with gold regarding calls allowed to
    go via a plt call stub or toc-adjusting stub without a following nop.
    A long time ago ld allowed tail calls, but this is wrong because we'll
    return to the caller's caller with the wrong toc pointer.  I fixed
    that for shared libraries but allowed tail calls in an executable for
    some reason.  Probably just muddy thinking on my part, because there's
    no difference between an executable and a shared library regarding the
    need to restore the toc pointer.  Perhaps it was because some testcase
    failed, most likely due to the g++ issue I comment on in the patch.

From Alan Modra: 29 Aug 2014 01:22:29 +0000: PowerPC64 call lacks nop error:
    Enough people accidentally or otherwise use -mcmodel=small then wonder
    why a call that is local is behaving as if it is going via the PLT.

	* elf64-ppc.c (ppc64_elf_relocate_section): Report a different
	error for calls via a toc adjusting stub without a nop.
This commit is contained in:
christos 2015-01-02 19:50:02 +00:00
parent 52e8eb1316
commit 88c1089d96
1 changed files with 76 additions and 44 deletions
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120
external/gpl3/binutils/dist/bfd/elf64-ppc.c vendored
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@ -3618,9 +3618,6 @@ struct ppc_stub_hash_entry {
struct ppc_link_hash_entry *h;
struct plt_entry *plt_ent;
/* And the reloc addend that this was derived from. */
bfd_vma addend;
/* Where this stub is being called from, or, in the case of combined
stub sections, the first input section in the group. */
asection *id_sec;
@ -11669,7 +11666,6 @@ ppc64_elf_size_stubs (struct bfd_link_info *info, bfd_signed_vma group_size,
}
stub_entry->h = hash;
stub_entry->plt_ent = plt_ent;
stub_entry->addend = irela->r_addend;
if (stub_entry->h != NULL)
htab->stub_globals += 1;
@ -12910,60 +12906,96 @@ ppc64_elf_relocate_section (bfd *output_bfd,
{
bfd_boolean can_plt_call = FALSE;
/* All of these stubs will modify r2, so there must be a
branch and link followed by a nop. The nop is
replaced by an insn to restore r2. */
if (rel->r_offset + 8 <= input_section->size)
{
unsigned long nop;
nop = bfd_get_32 (input_bfd, contents + rel->r_offset + 4);
if (nop == NOP
|| nop == CROR_151515 || nop == CROR_313131)
unsigned long br;
br = bfd_get_32 (input_bfd,
contents + rel->r_offset);
if ((br & 1) != 0)
{
if (h != NULL
&& (h == htab->tls_get_addr_fd
|| h == htab->tls_get_addr)
&& !htab->no_tls_get_addr_opt)
unsigned long nop;
nop = bfd_get_32 (input_bfd,
contents + rel->r_offset + 4);
if (nop == NOP
|| nop == CROR_151515 || nop == CROR_313131)
{
/* Special stub used, leave nop alone. */
if (h != NULL
&& (h == htab->tls_get_addr_fd
|| h == htab->tls_get_addr)
&& !htab->no_tls_get_addr_opt)
{
/* Special stub used, leave nop alone. */
}
else
bfd_put_32 (input_bfd, LD_R2_40R1,
contents + rel->r_offset + 4);
can_plt_call = TRUE;
}
else
bfd_put_32 (input_bfd, LD_R2_40R1,
contents + rel->r_offset + 4);
}
}
if (!can_plt_call && h != NULL)
{
const char *name = h->elf.root.root.string;
if (*name == '.')
++name;
if (strncmp (name, "__libc_start_main", 17) == 0
&& (name[17] == 0 || name[17] == '@'))
{
/* Allow crt1 branch to go via a toc adjusting
stub. Other calls that never return could do
the same, if we could detect such. */
can_plt_call = TRUE;
}
}
if (!can_plt_call)
{
/* g++ as of 20130507 emits self-calls without a
following nop. This is arguably wrong since we
have conflicting information. On the one hand a
global symbol and on the other a local call
sequence, but don't error for this special case.
It isn't possible to cheaply verify we have
exactly such a call. Allow all calls to the same
section. */
asection *code_sec = sec;
if (get_opd_info (sec) != NULL)
{
bfd_vma off = (relocation + addend
- sec->output_section->vma
- sec->output_offset);
opd_entry_value (sec, off, &code_sec, NULL, FALSE);
}
if (code_sec == input_section)
can_plt_call = TRUE;
}
if (!can_plt_call)
{
if (stub_entry->stub_type == ppc_stub_plt_call
|| stub_entry->stub_type == ppc_stub_plt_call_r2save)
{
/* If this is a plain branch rather than a branch
and link, don't require a nop. However, don't
allow tail calls in a shared library as they
will result in r2 being corrupted. */
unsigned long br;
br = bfd_get_32 (input_bfd, contents + rel->r_offset);
if (info->executable && (br & 1) == 0)
can_plt_call = TRUE;
else
stub_entry = NULL;
}
else if (h != NULL
&& strcmp (h->elf.root.root.string,
".__libc_start_main") == 0)
{
/* Allow crt1 branch to go via a toc adjusting stub. */
can_plt_call = TRUE;
}
info->callbacks->einfo
(_("%P: %H: call to `%T' lacks nop, can't restore toc; "
"recompile with -fPIC"),
input_bfd, input_section, rel->r_offset, sym_name);
else
{
info->callbacks->einfo
(_("%P: %H: call to `%T' lacks nop, can't restore toc; "
"recompile with -fPIC"),
input_bfd, input_section, rel->r_offset, sym_name);
bfd_set_error (bfd_error_bad_value);
ret = FALSE;
}
info->callbacks->einfo
(_("%P: %H: call to `%T' lacks nop, can't restore toc; "
"(-mcmodel=small toc adjust stub)"),
input_bfd, input_section, rel->r_offset, sym_name);
bfd_set_error (bfd_error_bad_value);
ret = FALSE;
}
if (can_plt_call