H.J. Lu ee2fdd6f36 x86: Support Intel IBT with IBT property and IBT-enable PLT
To support IBT in Intel Control-flow Enforcement Technology (CET)
instructions:

https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf

 #define GNU_PROPERTY_X86_FEATURE_1_AND 0xc0000002

 #define GNU_PROPERTY_X86_FEATURE_1_IBT (1U << 0)

are added to GNU program properties to indicate that all executable
sections are compatible with IBT when ENDBR instruction starts each
valid target where an indirect branch instruction can land.

GNU_PROPERTY_X86_FEATURE_1_IBT is set on output only if it is set on
all relocatable inputs.

The followings changes are made to the Procedure Linkage Table (PLT):

1. For 64-bit x86-64,  PLT is changed to

PLT0:  push       GOT[1]
       bnd jmp    *GOT[2]
       nop
...
PLTn:  endbr64
       push       namen_reloc_index
       bnd jmp    PLT0

together with the second PLT section:

PLTn:  endbr64
       bnd jmp   *GOT[namen_index]
       nop

BND prefix is also added so that IBT-enabled PLT is compatible with MPX.

2. For 32-bit x86-64 (x32) and i386,  PLT is changed to

PLT0:  push       GOT[1]
       jmp        *GOT[2]
       nop
...
PLTn:  endbr64                                 # endbr32 for i386.
       push       namen_reloc_index
       jmp        PLT0

together with the second PLT section:

PLTn:  endbr64                                 # endbr32 for i386.
       jmp       *GOT[namen_index]
       nop

BND prefix isn't used since MPX isn't supported on x32 and BND registers
aren't used in parameter passing on i386.

GOT is an array of addresses.  Initially, GOT[namen_index] is filled
with the address of the ENDBR instruction of the corresponding entry
in the first PLT section.  The function, namen, is called via the
ENDBR instruction in the second PLT entry.  GOT[namen_index] is updated
to the actual address of the function, namen, at run-time.

2 linker command line options are added:

1. -z ibtplt: Generate IBT-enabled PLT.
2. -z ibt: Generate GNU_PROPERTY_X86_FEATURE_1_IBT in GNU program
properties as well as IBT-enabled PLT.

bfd/

	* elf32-i386.c (elf_i386_lazy_ibt_plt0_entry): New.
	(elf_i386_lazy_ibt_plt_entry): Likewise.
	(elf_i386_pic_lazy_ibt_plt0_entry): Likewise.
	(elf_i386_non_lazy_ibt_plt_entry): Likewise.
	(elf_i386_pic_non_lazy_ibt_plt_entry): Likewise.
	(elf_i386_eh_frame_lazy_ibt_plt): Likewise.
	(elf_i386_lazy_plt_layout): Likewise.
	(elf_i386_non_lazy_plt_layout): Likewise.
	(elf_i386_link_hash_entry): Add plt_second.
	(elf_i386_link_hash_table): Add plt_second and
	plt_second_eh_frame.
	(elf_i386_allocate_dynrelocs): Use the second PLT if needed.
	(elf_i386_size_dynamic_sections): Use .plt.got unwind info for
	the second PLT.  Check the second PLT.
	(elf_i386_relocate_section): Use the second PLT to resolve
	PLT reference if needed.
	(elf_i386_finish_dynamic_symbol): Fill and use the second PLT if
	needed.
	(elf_i386_finish_dynamic_sections): Set sh_entsize on the
	second PLT.  Generate unwind info for the second PLT.
	(elf_i386_plt_type): Add plt_second.
	(elf_i386_get_synthetic_symtab): Support the second PLT.
	(elf_i386_parse_gnu_properties): Support
	GNU_PROPERTY_X86_FEATURE_1_AND.
	(elf_i386_merge_gnu_properties): Support
	GNU_PROPERTY_X86_FEATURE_1_AND.  If info->ibt is set, turn
	on GNU_PROPERTY_X86_FEATURE_1_IBT
	(elf_i386_link_setup_gnu_properties): If info->ibt is set,
	turn on GNU_PROPERTY_X86_FEATURE_1_IBT.  Use IBT-enabled PLT
	for info->ibtplt, info->ibt or GNU_PROPERTY_X86_FEATURE_1_IBT
	is set on all relocatable inputs.
	* elf64-x86-64.c (elf_x86_64_lazy_ibt_plt_entry): New.
	(elf_x32_lazy_ibt_plt_entry): Likewise.
	(elf_x86_64_non_lazy_ibt_plt_entry): Likewise.
	(elf_x32_non_lazy_ibt_plt_entry): Likewise.
	(elf_x86_64_eh_frame_lazy_ibt_plt): Likewise.
	(elf_x32_eh_frame_lazy_ibt_plt): Likewise.
	(elf_x86_64_lazy_ibt_plt): Likewise.
	(elf_x32_lazy_ibt_plt): Likewise.
	(elf_x86_64_non_lazy_ibt_plt): Likewise.
	(elf_x32_non_lazy_ibt_plt): Likewise.
	(elf_x86_64_get_synthetic_symtab): Support the second PLT.
	(elf_x86_64_parse_gnu_properties): Support
	GNU_PROPERTY_X86_FEATURE_1_AND.
	(elf_x86_64_merge_gnu_properties): Support
	GNU_PROPERTY_X86_FEATURE_1_AND.  If info->ibt is set, turn
	on GNU_PROPERTY_X86_FEATURE_1_IBT
	(elf_x86_64_link_setup_gnu_properties): If info->ibt is set,
	turn on GNU_PROPERTY_X86_FEATURE_1_IBT.  Use IBT-enabled PLT
	for info->ibtplt, info->ibt or GNU_PROPERTY_X86_FEATURE_1_IBT
	is set on all relocatable inputs.

binutils/

	* readelf.c (decode_x86_feature): New.
	(print_gnu_property_note): Call decode_x86_feature on
	GNU_PROPERTY_X86_FEATURE_1_AND.
	* testsuite/binutils-all/i386/empty.d: New file.
	* testsuite/binutils-all/i386/empty.s: Likewise.
	* testsuite/binutils-all/i386/ibt.d: Likewise.
	* testsuite/binutils-all/i386/ibt.s: Likewise.
	* testsuite/binutils-all/x86-64/empty-x32.d: Likewise.
	* testsuite/binutils-all/x86-64/empty.d: Likewise.
	* testsuite/binutils-all/x86-64/empty.s: Likewise.
	* testsuite/binutils-all/x86-64/ibt-x32.d: Likewise.
	* testsuite/binutils-all/x86-64/ibt.d: Likewise.
	* testsuite/binutils-all/x86-64/ibt.s: Likewise.

include/

	* bfdlink.h (bfd_link_info): Add ibtplt and ibt.
	* elf/common.h (GNU_PROPERTY_X86_FEATURE_1_AND): New.
	(GNU_PROPERTY_X86_FEATURE_1_IBT): Likewise.

ld/

	* Makefile.am (ELF_X86_DEPS): Add $(srcdir)/emulparams/cet.sh.
	* Makefile.in: Regenerated.
	* NEWS: Mention GNU_PROPERTY_X86_FEATURE_1_IBT, -z ibtplt
	and -z ibt.
	* emulparams/cet.sh: New file.
	* testsuite/ld-i386/ibt-plt-1.d: Likewise.
	* testsuite/ld-i386/ibt-plt-1.s: Likewise.
	* testsuite/ld-i386/ibt-plt-2.s: Likewise.
	* testsuite/ld-i386/ibt-plt-2a.d: Likewise.
	* testsuite/ld-i386/ibt-plt-2b.d: Likewise.
	* testsuite/ld-i386/ibt-plt-2c.d: Likewise.
	* testsuite/ld-i386/ibt-plt-2d.d: Likewise.
	* testsuite/ld-i386/ibt-plt-3.s: Likewise.
	* testsuite/ld-i386/ibt-plt-3a.d: Likewise.
	* testsuite/ld-i386/ibt-plt-3b.d: Likewise.
	* testsuite/ld-i386/ibt-plt-3c.d: Likewise.
	* testsuite/ld-i386/ibt-plt-3d.d: Likewise.
	* testsuite/ld-i386/plt-main-ibt.dd: Likewise.
	* testsuite/ld-i386/plt-pie-ibt.dd: Likewise.
	* testsuite/ld-i386/property-x86-empty.s: Likewise.
	* testsuite/ld-i386/property-x86-ibt.s: Likewise.
	* testsuite/ld-i386/property-x86-ibt1a.d: Likewise.
	* testsuite/ld-i386/property-x86-ibt1b.d: Likewise.
	* testsuite/ld-i386/property-x86-ibt2.d: Likewise.
	* testsuite/ld-i386/property-x86-ibt3a.d: Likewise.
	* testsuite/ld-i386/property-x86-ibt3b.d: Likewise.
	* testsuite/ld-i386/property-x86-ibt4.d: Likewise.
	* testsuite/ld-i386/property-x86-ibt5.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-1-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-1.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-1.s: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2.s: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2a-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2a.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2b-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2b.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2c-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2c.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2d-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2d.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3.s: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3a-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3a.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3b-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3b.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3c-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3c.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3d-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3d.d: Likewise.
	* testsuite/ld-x86-64/plt-main-ibt-now.rd: Likewise.
	* testsuite/ld-x86-64/plt-main-ibt-x32.dd: Likewise.
	* testsuite/ld-x86-64/plt-main-ibt.dd: Likewise.
	* testsuite/ld-x86-64/property-x86-empty.s: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt.s: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt1a-x32.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt1a.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt1b-x32.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt1b.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt2-x32.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt2.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt3a-x32.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt3a.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt3b-x32.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt3b.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt4-x32.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt4.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt5-x32.d: Likewise.
	* testsuite/ld-x86-64/property-x86-ibt5.d: Likewise.
	* emulparams/elf32_x86_64.sh: Source emulparams/cet.sh.
	(TINY_READONLY_SECTION): Add .plt.sec.
	* emulparams/elf_i386.sh: Likewise.
	* emulparams/elf_x86_64.sh: Source emulparams/cet.sh.
	* ld.texinfo: Document -z ibtplt and -z ibt.
	* testsuite/ld-i386/i386.exp: Run IBT and IBT PLT tests.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-x86-64/pr21481b.S (check): Updated for x32.
2017-06-22 05:44:53 -07:00
2017-06-02 08:04:59 -07:00

		   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.
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