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Alan Modra 5474d94f03 dynrelro section for read-only dynamic symbols copied into executable
Variables defined in shared libraries are copied into an executable's
.bss section when code in the executable is non-PIC and thus would
require dynamic text relocations to access the variable directly in
the shared library.  Recent x86 toolchains also copy variables into
the executable to gain a small speed improvement.

The problem is that if the variable was originally read-only, the copy
in .bss is writable, potentially opening a security hole.  This patch
cures that problem by putting the copy in a section that becomes
read-only after ld.so relocation, provided -z relro is in force.

The patch also fixes a microblaze linker segfault on attempting to
use dynamic bss variables.

bfd/
	PR ld/20995
	* elf-bfd.h (struct elf_link_hash_table): Add sdynrelro and
	sreldynrelro.
	(struct elf_backend_data): Add want_dynrelro.
	* elfxx-target.h (elf_backend_want_dynrelro): Define.
	(elfNN_bed): Update initializer.
	* elflink.c (_bfd_elf_create_dynamic_sections): Create
	sdynrelro and sreldynrelro sections.
	* elf32-arm.c (elf32_arm_adjust_dynamic_symbol): Place variables
	copied into the executable from read-only sections into sdynrelro.
	(elf32_arm_size_dynamic_sections): Handle sdynrelro.
	(elf32_arm_finish_dynamic_symbol): Select sreldynrelro for
	dynamic relocs in sdynrelro.
	(elf_backend_want_dynrelro): Define.
	* elf32-hppa.c (elf32_hppa_adjust_dynamic_symbol)
	(elf32_hppa_size_dynamic_sections, elf32_hppa_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf32-i386.c (elf_i386_adjust_dynamic_symbol)
	(elf_i386_size_dynamic_sections, elf_i386_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf32-metag.c (elf_metag_adjust_dynamic_symbol)
	(elf_metag_size_dynamic_sections, elf_metag_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol)
	(microblaze_elf_size_dynamic_sections)
	(microblaze_elf_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf32-nios2.c (nios2_elf32_finish_dynamic_symbol)
	(nios2_elf32_adjust_dynamic_symbol)
	(nios2_elf32_size_dynamic_sections)
	(elf_backend_want_dynrelro): As above.
	* elf32-or1k.c (or1k_elf_finish_dynamic_symbol)
	(or1k_elf_adjust_dynamic_symbol, or1k_elf_size_dynamic_sections)
	(elf_backend_want_dynrelro): As above.
	* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol)
	(ppc_elf_size_dynamic_sections, ppc_elf_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf32-s390.c (elf_s390_adjust_dynamic_symbol)
	(elf_s390_size_dynamic_sections, elf_s390_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf32-tic6x.c (elf32_tic6x_adjust_dynamic_symbol)
	(elf32_tic6x_size_dynamic_sections)
	(elf32_tic6x_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf32-tilepro.c (tilepro_elf_adjust_dynamic_symbol)
	(tilepro_elf_size_dynamic_sections)
	(tilepro_elf_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol)
	(ppc64_elf_size_dynamic_sections, ppc64_elf_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf64-s390.c (elf_s390_adjust_dynamic_symbol)
	(elf_s390_size_dynamic_sections, elf_s390_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elf64-x86-64.c (elf_x86_64_adjust_dynamic_symbol)
	(elf_x86_64_size_dynamic_sections)
	(elf_x86_64_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elfnn-aarch64.c (elfNN_aarch64_adjust_dynamic_symbol)
	(elfNN_aarch64_size_dynamic_sections)
	(elfNN_aarch64_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elfnn-riscv.c (riscv_elf_adjust_dynamic_symbol)
	(riscv_elf_size_dynamic_sections, riscv_elf_finish_dynamic_symbol)
	(elf_backend_want_dynrelro): As above.
	* elfxx-mips.c (_bfd_mips_elf_adjust_dynamic_symbol)
	(_bfd_mips_elf_size_dynamic_sections)
	(_bfd_mips_vxworks_finish_dynamic_symbol): As above.
	* elfxx-sparc.c (_bfd_sparc_elf_adjust_dynamic_symbol)
	(_bfd_sparc_elf_size_dynamic_sections)
	(_bfd_sparc_elf_finish_dynamic_symbol): As above.
	* elfxx-tilegx.c (tilegx_elf_adjust_dynamic_symbol)
	(tilegx_elf_size_dynamic_sections)
	(tilegx_elf_finish_dynamic_symbol): As above.
	* elf32-mips.c (elf_backend_want_dynrelro): Define.
	* elf64-mips.c (elf_backend_want_dynrelro): Define.
	* elf32-sparc.c (elf_backend_want_dynrelro): Define.
	* elf64-sparc.c (elf_backend_want_dynrelro): Define.
	* elf32-tilegx.c (elf_backend_want_dynrelro): Define.
	* elf64-tilegx.c (elf_backend_want_dynrelro): Define.
	* elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol): Tidy.
	(microblaze_elf_size_dynamic_sections): Handle sdynbss.
	* elf32-nios2.c (nios2_elf32_size_dynamic_sections): Make use
	of linker shortcuts to dynamic sections rather than comparing
	names.  Correctly set "got" flag.
ld/
	PR ld/20995
	* testsuite/ld-arm/farcall-mixed-app-v5.d: Update to suit changed
	stub hash table traversal caused by section id increment.  Accept
	the previous output too.
	* testsuite/ld-arm/farcall-mixed-app.d: Likewise.
	* testsuite/ld-arm/farcall-mixed-lib-v4t.d: Likewise.
	* testsuite/ld-arm/farcall-mixed-lib.d: Likewise.
	* testsuite/ld-elf/pr20995a.s, * testsuite/ld-elf/pr20995b.s,
	* testsuite/ld-elf/pr20995.r: New test.
	* testsuite/ld-elf/elf.exp: Run it.
2016-12-26 13:47:51 +10:30
bfd dynrelro section for read-only dynamic symbols copied into executable 2016-12-26 13:47:51 +10:30
binutils MIPS16: Add ASMACRO instruction support 2016-12-23 19:55:21 +00:00
config sync binutils config/ with gcc 2016-12-08 21:35:11 +10:30
cpu Add fall through comment to source in cpu/ 2016-10-06 22:48:37 +10:30
elfcpp Add support for MIPS .rld_map section. 2016-06-20 12:16:26 -07:00
etc Fix compile time warning messages building with gcc v6.1.1 2016-06-13 10:49:26 +01:00
gas MIPS16: Add ASMACRO instruction support 2016-12-23 19:55:21 +00:00
gdb Fix more cases of improper test names 2016-12-23 10:52:18 -06:00
gold Bump gold version number to 1.14. 2016-12-23 08:00:13 -08:00
gprof Bump version to 2.28.51 2016-12-23 09:50:53 +01:00
include MIPS16: Add ASMACRO instruction support 2016-12-23 19:55:21 +00:00
intl Regen intl/configure 2015-08-31 12:53:36 +09:30
ld dynrelro section for read-only dynamic symbols copied into executable 2016-12-26 13:47:51 +10:30
libdecnumber Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
libiberty Port c++/78252 from GCC 2016-12-12 12:52:37 -05:00
opcodes MIPS16: Add ASMACRO instruction support 2016-12-23 19:55:21 +00:00
readline Improve MinGW support in Readline 2016-09-17 11:50:37 +03:00
sim Fix bugs with float compare and Inf operands. 2016-12-21 12:33:12 -08:00
texinfo
zlib sync binutils config/ with gcc 2016-12-08 21:35:11 +10:30
.cvsignore
.gitattributes
.gitignore Add archives and make stamps to the .gitignore file. 2016-09-27 15:10:42 +01:00
ChangeLog sync binutils config/ with gcc 2016-12-08 21:35:11 +10:30
compile
config-ml.in Sync toplevel files with GCC 2015-07-27 07:49:05 -07:00
config.guess Sync config.sub,config.guess with upstream. 2016-11-07 13:08:55 -08:00
config.rpath
config.sub Sync config.sub,config.guess with upstream. 2016-11-07 13:08:55 -08:00
configure sync binutils config/ with gcc 2016-12-08 21:35:11 +10:30
configure.ac Add support for Fushia OS. 2016-12-02 10:44:29 +00:00
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB
depcomp
djunpack.bat
install-sh
libtool.m4 Sync top-level btool.m4 with GCC 2016-01-12 08:44:52 -08:00
lt~obsolete.m4
ltgcc.m4
ltmain.sh
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS
Makefile.def Sync top-level Makefile.def with GCC 2016-01-12 08:34:40 -08:00
Makefile.in Add dependencies to configure rule 2016-05-28 22:36:04 +09:30
Makefile.tpl Add dependencies to configure rule 2016-05-28 22:36:04 +09:30
makefile.vms
missing
mkdep
mkinstalldirs
move-if-change
README
README-maintainer-mode
setup.com
src-release.sh fix gdb version parsing in src-release.sh 2016-01-17 10:01:55 +04:00
symlink-tree
ylwrap

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.