binutils-gdb/ld
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
..
emulparams x86: Support Intel IBT with IBT property and IBT-enable PLT 2017-06-22 05:44:53 -07:00
emultempl Rewrite __start and __stop symbol handling 2017-06-16 23:38:28 +09:30
po Add Serbian translation for the LD directory. 2017-01-27 11:27:50 +00:00
scripttempl Move location of .jumptables section and add .hightext section to AVR linker script. 2017-06-14 12:23:39 +01:00
testsuite x86: Support Intel IBT with IBT property and IBT-enable PLT 2017-06-22 05:44:53 -07:00
.gitignore
aclocal.m4 Regenerate Makefile.in/aclocal.m4 automake 1.11.6 2016-04-15 16:20:55 -07:00
ChangeLog x86: Support Intel IBT with IBT property and IBT-enable PLT 2017-06-22 05:44:53 -07:00
ChangeLog-0001
ChangeLog-0203
ChangeLog-2004
ChangeLog-2005
ChangeLog-2006
ChangeLog-2007
ChangeLog-2008 strip off +x bits on non-executable/script files 2013-12-07 02:03:03 -05:00
ChangeLog-2009 Remove trailing spaces in ld 2015-08-12 04:46:43 -07:00
ChangeLog-2010
ChangeLog-2011
ChangeLog-2012
ChangeLog-2013 New Year - binutils ChangeLog rotation 2014-01-08 05:32:12 -08:00
ChangeLog-2014 ChangeLog rotatation and copyright year update 2015-01-02 00:53:45 +10:30
ChangeLog-2015 binutils ChangeLog rotation 2016-01-01 22:59:17 +10:30
ChangeLog-2016 ChangeLog rotation 2017-01-02 13:55:05 +10:30
ChangeLog-9197 Remove trailing spaces in ld 2015-08-12 04:46:43 -07:00
ChangeLog-9899
config.in Introduce --enable-new-dtags configure option. 2017-06-05 09:58:05 +09:30
configure Introduce --enable-new-dtags configure option. 2017-06-05 09:58:05 +09:30
configure.ac Introduce --enable-new-dtags configure option. 2017-06-05 09:58:05 +09:30
configure.host Run more ld tests when not native 2017-01-02 23:48:08 +10:30
configure.tgt Accept more epiphany targets 2017-06-14 06:59:37 +02:00
deffile.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
deffilep.y Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
dep-in.sed
elf-hints-local.h
fdl.texi
gen-doc.texi Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
genscrba.sh
genscripts.sh Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
h8-doc.texi Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ld.h ld: Fix spelling mistake in comment. 2017-06-06 10:15:27 +01:00
ld.texinfo x86: Support Intel IBT with IBT property and IBT-enable PLT 2017-06-22 05:44:53 -07:00
ldbuildid.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldbuildid.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldcref.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldctor.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldctor.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldemul.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldemul.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldexp.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldexp.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldfile.c Treat a prefix of "$SYSROOT" in the same way as "=" when parsing linker search paths. 2017-05-18 15:07:59 +01:00
ldfile.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldgram.y ld: Allow section groups to be resolved as part of a relocatable link 2017-06-06 09:53:38 +01:00
ldint.texinfo Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldlang.c Rewrite __start and __stop symbol handling 2017-06-16 23:38:28 +09:30
ldlang.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldlex-wrapper.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldlex.h ld: Allow section groups to be resolved as part of a relocatable link 2017-06-06 09:53:38 +01:00
ldlex.l ld: Allow section groups to be resolved as part of a relocatable link 2017-06-06 09:53:38 +01:00
ldmain.c ld: Allow section groups to be resolved as part of a relocatable link 2017-06-06 09:53:38 +01:00
ldmain.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldmisc.c LD: vfinfo: Make clever formatters consistent WRT function name reporting 2017-02-15 13:41:51 +00:00
ldmisc.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldver.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldver.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldwrite.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldwrite.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
lexsup.c Correct "ld --help" to display "-z stack-size=SIZE" 2017-06-15 12:30:53 -07:00
MAINTAINERS Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
Makefile.am x86: Support Intel IBT with IBT property and IBT-enable PLT 2017-06-22 05:44:53 -07:00
Makefile.in x86: Support Intel IBT with IBT property and IBT-enable PLT 2017-06-22 05:44:53 -07:00
mri.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
mri.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
NEWS x86: Support Intel IBT with IBT property and IBT-enable PLT 2017-06-22 05:44:53 -07:00
pe-dll.c Support pe-bigobj-x86-64 as an output format in 64-bit PE based linkers. 2017-05-09 14:42:43 +01:00
pe-dll.h PR 21274, ld segfaults linking PE DLL 2017-04-11 19:49:13 +09:30
pep-dll.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
pep-dll.h PR 21274, ld segfaults linking PE DLL 2017-04-11 19:49:13 +09:30
plugin.c Rename non_ir_ref to non_ir_ref_regular 2017-05-16 10:35:02 +09:30
plugin.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
README Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
stamp-h.in
sysdep.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
testplug.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
testplug2.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
testplug3.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
testplug4.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
TODO

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		README for LD

This is the GNU linker.  It is distributed with other "binary
utilities" which should be in ../binutils.  See ../binutils/README for
more general notes, including where to send bug reports.

There are many features of the linker:

* The linker uses a Binary File Descriptor library (../bfd)
  that it uses to read and write object files.  This helps
  insulate the linker itself from the format of object files.

* The linker supports a number of different object file
  formats.  It can even handle multiple formats at once:
  Read two input formats and write a third.

* The linker can be configured for cross-linking.

* The linker supports a control language.

* There is a user manual (ld.texinfo), as well as the
  beginnings of an internals manual (ldint.texinfo).

Installation
============

See ../binutils/README.

If you want to make a cross-linker, you may want to specify
a different search path of -lfoo libraries than the default.
You can do this by setting the LIB_PATH variable in ./Makefile
or using the --with-lib-path configure switch.

To build just the linker, make the target all-ld from the top level
directory (one directory above this one).

Porting to a new target
=======================

See the ldint.texinfo manual.

Reporting bugs etc
===========================

See ../binutils/README.

Known problems
==============

The Solaris linker normally exports all dynamic symbols from an
executable.  The GNU linker does not do this by default.  This is
because the GNU linker tries to present the same interface for all
similar targets (in this case, all native ELF targets).  This does not
matter for normal programs, but it can make a difference for programs
which try to dlopen an executable, such as PERL or Tcl.  You can make
the GNU linker export all dynamic symbols with the -E or
--export-dynamic command line option.

HP/UX 9.01 has a shell bug that causes the linker scripts to be
generated incorrectly.  The symptom of this appears to be "fatal error
- scanner input buffer overflow" error messages.  There are various
workarounds to this:
  * Build and install bash, and build with "make SHELL=bash".
  * Update to a version of HP/UX with a working shell (e.g., 9.05).
  * Replace "(. ${srcdir}/scripttempl/${SCRIPT_NAME}.sc)" in
    genscripts.sh with "sh ${srcdir}..." (no parens) and make sure the
    emulparams script used exports any shell variables it sets.

Copyright (C) 2012-2017 Free Software Foundation, Inc.

Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.