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PR 21847, PowerPC64 --plt-localentry again

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This makes ld warn about --plt-localentry if a version of glibc
without the necessary ld.so checks is detected, and revises the
documentation.

bfd/
	* elf64-ppc.c (ppc64_elf_tls_setup): Warn on --plt-localentry
	without ld.so checks.
gold/
	* powerpc.cc (Target_powerpc::scan_relocs): Warn on --plt-localentry
	without ld.so checks.
ld/
	* ld.texinfo (plt-localentry): Revise.
This commit is contained in:
Alan Modra 2017-07-31 10:18:46 +09:30
parent 93e0a1eab1
commit d44c746aed
6 changed files with 29 additions and 2 deletions
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5
bfd/ChangeLog
View File

@ -1,3 +1,8 @@
2017-07-31 Alan Modra <amodra@gmail.com>
* elf64-ppc.c (ppc64_elf_tls_setup): Warn on --plt-localentry
without ld.so checks.
2017-07-29 Alan Modra <amodra@gmail.com>
PR 21847

6
bfd/elf64-ppc.c
View File

@ -8372,6 +8372,12 @@ ppc64_elf_tls_setup (struct bfd_link_info *info)
--plt-localentry can cause trouble. */
if (htab->params->plt_localentry0 < 0)
htab->params->plt_localentry0 = 0;
if (htab->params->plt_localentry0
&& elf_link_hash_lookup (&htab->elf, "GLIBC_2.26",
FALSE, FALSE, FALSE) == NULL)
info->callbacks->einfo
(_("%P: warning: --plt-localentry is especially dangerous without "
"ld.so support to detect ABI violations.\n"));
htab->tls_get_addr = ((struct ppc_link_hash_entry *)
elf_link_hash_lookup (&htab->elf, ".__tls_get_addr",

5
gold/ChangeLog
View File

@ -1,3 +1,8 @@
2017-07-31 Alan Modra <amodra@gmail.com>
* powerpc.cc (Target_powerpc::scan_relocs): Warn on --plt-localentry
without ld.so checks.
2017-07-29 Alan Modra <amodra@gmail.com>
PR 21847

4
gold/powerpc.cc
View File

@ -7660,6 +7660,10 @@ Target_powerpc<size, big_endian>::scan_relocs(
{
if (parameters->options().user_set_plt_localentry())
plt_localentry0 = parameters->options().plt_localentry();
if (plt_localentry0
&& symtab->lookup("GLIBC_2.26", NULL) == NULL)
gold_warning(_("--plt-localentry is especially dangerous without "
"ld.so support to detect ABI violations"));
}
this->plt_localentry0_ = plt_localentry0;
this->plt_localentry0_init_ = true;

4
ld/ChangeLog
View File

@ -1,3 +1,7 @@
2017-07-31 Alan Modra <amodra@gmail.com>
* ld.texinfo (plt-localentry): Revise.
2017-07-29 Alan Modra <amodra@gmail.com>
* ld.texinfo (plt-localentry): Document.

7
ld/ld.texinfo
View File

@ -7613,8 +7613,11 @@ Such an external function can be called via the PLT without saving r2
or restoring it on return, avoiding a common load-hit-store for small
functions. The optimization is attractive, with up to 40% reduction
in execution time for a small function, but can result in symbol
interposition failures. Use with care. @option{--no-plt-localentry}
is the default.
interposition failures. Also, minor changes in a shared library,
including system libraries, can cause a function that was localentry:0
to become localentry:8. This will result in a dynamic loader
complaint and failure to run. The option is experimental, use with
care. @option{--no-plt-localentry} is the default.
@end table
@ifclear GENERIC