[binutils-gdb] Add extern_protected_data and set it for x86

[sergiodj+buildbot at redhat dot com]

*** TEST RESULTS FOR COMMIT f74839702efcea048ac61374b1539ae81e7c86cc ***

Author: H.J. Lu <hjl.tools@gmail.com>
Branch: master
Commit: f74839702efcea048ac61374b1539ae81e7c86cc

Add extern_protected_data and set it for x86
Re-apply: commit ca3fe95e469b9daec153caa2c90665f5daaec2b5

With copy relocation, address of protected data defined in the shared
library may be external.  This patch adds extern_protected_data and
changes _bfd_elf_symbol_refs_local_p to return false for protected data
if extern_protected_data is true.

This patch will break building shared libraries with protected data
symbols using GCCs older than GCC 5 without the bug fix for

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

GCC backport request should be made in the GCC bug report above.

To get correct run-time behavior on Linux, glibc 2.22 or above are
required, which have the bug fix for

https://sourceware.org/bugzilla/show_bug.cgi?id=17711

Backports for glibc 2.21, 2.20, 2.19 and 2.18 are on hjl/pr17711/2.21,
hjl/pr17711/2.20, hjl/pr17711/2.19 and hjl/pr17711/2.18 branches,
respectively, at

https://sourceware.org/git/?p=glibc.git;a=summary

bfd/

	PR ld/pr15228
	PR ld/pr17709
	* elf-bfd.h (elf_backend_data): Add extern_protected_data.
	* elf32-i386.c (elf_backend_extern_protected_data): New.
	Defined to 1.
	* elf64-x86-64.c (elf_backend_extern_protected_data): Likewise.
	* elflink.c (_bfd_elf_adjust_dynamic_copy): Don't error on
	copy relocs against protected symbols if extern_protected_data
	is true.
	(_bfd_elf_symbol_refs_local_p): Don't return true on protected
	non-function symbols if extern_protected_data is true.
	* elfxx-target.h (elf_backend_extern_protected_data): New.
	Default to 0.
	(elfNN_bed): Initialize extern_protected_data with
	elf_backend_extern_protected_data.

ld/testsuite/

	PR ld/pr15228
	PR ld/pr17709
	* ld-i386/i386.exp (i386tests): Add a test for PR ld/17709.
	* ld-i386/pr17709-nacl.rd: New file.
	* ld-i386/pr17709.rd: Likewise.
	* ld-i386/pr17709a.s: Likewise.
	* ld-i386/pr17709b.s: Likewise.
	* ld-i386/protected3.d: Updated.
	* ld-i386/protected3.s: Likewise.
	* ld-x86-64/pr17709-nacl.rd: New file.
	* ld-x86-64/pr17709.rd: Likewise.
	* ld-x86-64/pr17709a.s: Likewise.
	* ld-x86-64/pr17709b.s: Likewise.
	* ld-x86-64/protected3.d: Updated.
	* ld-x86-64/protected3.s: Likewise.
	* ld-x86-64/x86-64.exp (x86_64tests): Add a test for PR ld/17709.