binutils-gdb/ld
H.J. Lu 233cc9c13a Don't generate PLT for IFUNC GOT/pointer reference
If a backend supports it, PLT entry isn't needed when all references
to a STT_GNU_IFUNC symbols are done via GOT or static function pointers.
For GOT entries, We generate dynamic R_*_GLOB_DAT relocations for
preemptable symbols and R_*_IRELATIVE relocations for non-preemptable
symbols to update them with real function address.  For static pointer
pointers, we generate dynamic pointer relocations and store them in:

1. .rel[a].ifunc section in PIC object.
2. .rel[a].got section in dynamic executable.
3. .rel[a].iplt section in static executable.

We don't allocate GOT entry if it isn't used.

bfd/

	PR ld/20253
	* elf-bfd.h (_bfd_elf_allocate_ifunc_dyn_relocs): Add an
	bfd_boolean argument.
	* elf-ifunc.c (_bfd_elf_create_ifunc_sections): Replace
	"shared object" with "PIC object" in comments.
	(_bfd_elf_allocate_ifunc_dyn_relocs): Updated.  Replace
	"shared object" with "PIC object" in comments.  Avoid PLT if
	requested.  Generate dynamic relocations for non-GOT references.
	Make room for the special first entry in PLT and allocate PLT
	entry only for PLT and PC-relative references.  Store dynamic
	GOT relocations in .rel[a].iplt section for static executables.
	If PLT isn't used, always use GOT for symbol value.  Don't
	allocate GOT entry if it isn't used.
	* elf32-i386.c (elf_i386_check_relocs): Increment PLT reference
	count only in the code section.  Allocate dynamic pointer
	relocation against STT_GNU_IFUNC symbol in the non-code section.
	(elf_i386_adjust_dynamic_symbol): Increment PLT reference count
	only for PC-relative references.
	(elf_i386_allocate_dynrelocs): Pass TRUE to
	_bfd_elf_allocate_ifunc_dyn_relocs.
	(elf_i386_relocate_section): Allow R_386_GOT32/R_386_GOT32X
	relocations against STT_GNU_IFUNC symbols without PLT.  Generate
	dynamic pointer relocation against STT_GNU_IFUNC symbol in
	the non-code section and store it in the proper REL section.
	Don't allow non-pointer relocation against STT_GNU_IFUNC symbol
	without PLT.
	(elf_i386_finish_dynamic_symbol): Generate dynamic
	R_386_IRELATIVE and R_386_GLOB_DAT GOT relocations against
	STT_GNU_IFUNC symbols without PLT.
	(elf_i386_finish_dynamic_sections): Don't handle local
	STT_GNU_IFUNC symbols here.
	(elf_i386_output_arch_local_syms): Handle local STT_GNU_IFUNC
	symbols here.
	(elf_backend_output_arch_local_syms): New.
	* elf32-x86-64.c (elf_i386_check_relocs): Increment PLT reference
	count only in the code section.  Allocate dynamic pointer
	relocation against STT_GNU_IFUNC symbol in the non-code section.
	(elf_x86_64_adjust_dynamic_symbol): Increment PLT reference
	count only for PC-relative references.
	(elf_x86_64_allocate_dynrelocs): Pass TRUE to
	_bfd_elf_allocate_ifunc_dyn_relocs.
	(elf_x86_64_relocate_section): Allow R_X86_64_GOTPCREL,
	R_X86_64_GOTPCRELX, R_X86_64_REX_GOTPCRELX and
	R_X86_64_GOTPCREL64 relocations against STT_GNU_IFUNC symbols
	without PLT.  Generate dynamic pointer relocation against
	STT_GNU_IFUNC symbol in the non-code section and store it in
	the proper RELA section.  Don't allow non-pointer relocation
	against STT_GNU_IFUNC symbol without PLT.
	(elf_x86_64_finish_dynamic_symbol): Generate dynamic
	R_X86_64_IRELATIVE and R_X86_64_GLOB_DAT GOT relocations against
	STT_GNU_IFUNC symbols without PLT.
	(elf_x86_64_finish_dynamic_sections): Don't handle local
	STT_GNU_IFUNC symbols here.
	(elf_x86_64_output_arch_local_syms): Handle local STT_GNU_IFUNC
	symbols here.
	(elf_backend_output_arch_local_syms): New.
	* elfnn-aarch64.c (elfNN_aarch64_allocate_ifunc_dynrelocs):
	Pass FALSE to _bfd_elf_allocate_ifunc_dyn_relocs.

ld/

	PR ld/20253
	* testsuite/ld-i386/i386.exp: Run PR ld/20253 tests.
	* testsuite/ld-i386/no-plt.exp: Likewise.
	* testsuite/ld-x86-64/no-plt.exp: Likewise.
	* testsuite/ld-i386/pr13302.d: Remove .rel.plt section.
	* testsuite/ld-ifunc/ifunc-13-i386.d: Likewise.
	* testsuite/ld-ifunc/ifunc-13-x86-64.d: Likewise.
	* testsuite/ld-ifunc/ifunc-15-i386.d: Likewise.
	* testsuite/ld-ifunc/ifunc-15-x86-64.d: Likewise.
	* testsuite/ld-x86-64/pr13082-5a.d: Likewise.
	* testsuite/ld-x86-64/pr13082-5b.d: Likewise.
	* testsuite/ld-x86-64/pr13082-6a.d: Likewise.
	* testsuite/ld-x86-64/pr13082-6b.d: Likewise.
	* testsuite/ld-i386/pr20244-2a.d: Remove .plt section.
	* testsuite/ld-ifunc/ifunc-21-i386.d: Likewise.
	* testsuite/ld-ifunc/ifunc-21-x86-64.d: Likewise.
	* testsuite/ld-ifunc/ifunc-22-i386.d: Likewise.
	* testsuite/ld-ifunc/ifunc-22-x86-64.d: Likewise.
	* testsuite/ld-i386/pr20244-2b.d: Updated.
	* testsuite/ld-i386/pr20244-2c.d: Likewise.
	* testsuite/ld-ifunc/ifunc-18a-i386.d: Likewise.
	* testsuite/ld-ifunc/ifunc-18a-x86-64.d: Likewise.
	* testsuite/ld-ifunc/ifunc-18b-i386.d: Likewise.
	* testsuite/ld-ifunc/ifunc-18b-x86-64.d: Likewise.
	* testsuite/ld-i386/pr20253-1a.c: New file.
	* testsuite/ld-i386/pr20253-1b.S: Likewise.
	* testsuite/ld-i386/pr20253-1c.S: Likewise.
	* testsuite/ld-i386/pr20253-1d.S: Likewise.
	* testsuite/ld-i386/pr20253-2a.c: Likewise.
	* testsuite/ld-i386/pr20253-2b.S: Likewise.
	* testsuite/ld-i386/pr20253-2c.S: Likewise.
	* testsuite/ld-i386/pr20253-2d.S: Likewise.
	* testsuite/ld-i386/pr20253-3.d: Likewise.
	* testsuite/ld-i386/pr20253-3.s: Likewise.
	* testsuite/ld-i386/pr20253-4.s: Likewise.
	* testsuite/ld-i386/pr20253-4a.d: Likewise.
	* testsuite/ld-i386/pr20253-4b.d: Likewise.
	* testsuite/ld-i386/pr20253-4c.d: Likewise.
	* testsuite/ld-i386/pr20253-5.d: Likewise.
	* testsuite/ld-i386/pr20253-5.s: Likewise.
	* testsuite/ld-ifunc/ifunc-23-x86.s: Likewise.
	* testsuite/ld-ifunc/ifunc-23a-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-23b-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-23c-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-24-x86.s: Likewise.
	* testsuite/ld-ifunc/ifunc-24a-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-24b-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-24c-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-25-x86.s: Likewise.
	* testsuite/ld-ifunc/ifunc-25a-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-25b-x86.d: Likewise.
	* testsuite/ld-ifunc/ifunc-25c-x86.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1.s: Likewise.
	* testsuite/ld-x86-64/pr20253-1a.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1b.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1c.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1d.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1e.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1f.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1g.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1h.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1i.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1j.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1k.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1l.d: Likewise.
	* testsuite/ld-x86-64/pr20253-2a.c: Likewise.
	* testsuite/ld-x86-64/pr20253-2b.S: Likewise.
	* testsuite/ld-x86-64/pr20253-2c.S: Likewise.
	* testsuite/ld-x86-64/pr20253-2d.S: Likewise.
	* testsuite/ld-x86-64/pr20253-3.d: Likewise.
	* testsuite/ld-x86-64/pr20253-3.s: Likewise.
	* testsuite/ld-x86-64/pr20253-4.s: Likewise.
	* testsuite/ld-x86-64/pr20253-4a.d: Likewise.
	* testsuite/ld-x86-64/pr20253-4b.d: Likewise.
	* testsuite/ld-x86-64/pr20253-4c.d: Likewise.
	* testsuite/ld-x86-64/pr20253-4d.d: Likewise.
	* testsuite/ld-x86-64/pr20253-4e.d: Likewise.
	* testsuite/ld-x86-64/pr20253-4f.d: Likewise.
	* testsuite/ld-x86-64/pr20253-5.s: Likewise.
	* testsuite/ld-x86-64/pr20253-5a.d: Likewise.
	* testsuite/ld-x86-64/pr20253-5b.d: Likewise.
	* testsuite/ld-ifunc/ifunc-18a-i386.d: Remove extra IRELATIVE
	relocation.
	* testsuite/ld-ifunc/ifunc-18a-x86-64.d: Likewise.
	* testsuite/ld-ifunc/ifunc-18b-i386.d: Likewise.
	* testsuite/ld-ifunc/ifunc-18b-x86-64.d: Likewise.
	* testsuite/ld-ifunc/ifunc-18a.s: Fix a typo.
	* testsuite/ld-x86-64/x86-64.exp: Run pr20253-1 tests.
2016-06-18 09:17:25 -07:00
..
emulparams Add support for configuring for the ARM Phoenix target. 2016-05-23 13:53:07 +01:00
emultempl Return void from linker callbacks 2016-05-28 11:17:20 +09:30
po
scripttempl Provide the __bssstart and __bsssize symbols needed by the MSP430's crt0.o code. 2016-05-26 11:43:38 +01:00
testsuite Don't generate PLT for IFUNC GOT/pointer reference 2016-06-18 09:17:25 -07:00
.gitignore
aclocal.m4
ChangeLog Don't generate PLT for IFUNC GOT/pointer reference 2016-06-18 09:17:25 -07:00
ChangeLog-0001 Add copyright notices 2012-12-10 12:48:03 +00:00
ChangeLog-0203
ChangeLog-2004
ChangeLog-2005
ChangeLog-2006
ChangeLog-2007
ChangeLog-2008
ChangeLog-2009
ChangeLog-2010
ChangeLog-2011
ChangeLog-2012
ChangeLog-2013
ChangeLog-2014
ChangeLog-2015
ChangeLog-9197
ChangeLog-9899
config.in
configure Regenerate configure 2016-05-09 17:24:30 +09:30
configure.ac
configure.host
configure.tgt Allow ARC Linux targets that do not use uclibc. 2016-06-02 15:03:47 +01:00
deffile.h
deffilep.y
dep-in.sed
elf-hints-local.h
fdl.texi
gen-doc.texi
genscrba.sh
genscripts.sh
h8-doc.texi
ld.h
ld.texinfo [AArch64] Also puts value in place for R_AARCH64_RELATIVE 2016-05-03 11:59:37 +01:00
ldbuildid.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldbuildid.h
ldcref.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldctor.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldctor.h
ldemul.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldemul.h
ldexp.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldexp.h
ldfile.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldfile.h
ldgram.y
ldint.texinfo
ldlang.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldlang.h
ldlex-wrapper.c
ldlex.h
ldlex.l
ldmain.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldmain.h
ldmisc.c Delete bfd_my_archive macro 2016-06-14 13:24:37 +09:30
ldmisc.h
ldver.c
ldver.h
ldwrite.c Formatting fixes. 2016-06-14 13:25:21 +09:30
ldwrite.h
lexsup.c
MAINTAINERS
Makefile.am Add support for configuring for the ARM Phoenix target. 2016-05-23 13:53:07 +01:00
Makefile.in Add support for configuring for the ARM Phoenix target. 2016-05-23 13:53:07 +01:00
mri.c
mri.h
NEWS [AArch64] Also puts value in place for R_AARCH64_RELATIVE 2016-05-03 11:59:37 +01:00
pe-dll.c
pe-dll.h
pep-dll.c
pep-dll.h
plugin.c Delete bfd_my_archive macro 2016-06-14 13:24:37 +09:30
plugin.h
README
stamp-h.in
sysdep.h
testplug2.c Remove redundant sizeof on EXPECTED_VIEW_LENGTH 2016-05-14 05:51:28 -07:00
testplug3.c
testplug4.c Remove redundant sizeof on EXPECTED_VIEW_LENGTH 2016-05-14 05:51:28 -07:00
testplug.c
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) 2012-2016 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.