binutils-gdb/ld
H.J. Lu aec6b87e0b [x86] Resolve non-PIC undefweak symbols in executable
For i386 and x86-64, non-PIC references to undefined weak symbols are
resolved without dynamic relocation when creating executable.  Resolved
undefined weak symbols are removed from the dynamic symbol table in
executable.  One exception is on i386, we need resolved undefined weak
symbols in the dynamic symbol table in PIE if input relocatable files
contain branchs without PLT so that we can branch to 0 with dynamic
relocation in text section.

This makes behaviors of dynamic executable and position independent
executable predictable with mixed PIC and non-PIC references to undefined
weak symbols.  If all references to undefined weak symbols are PIC,
dynamic relocations against undefined weak symbols will be generated
in executable unless -z nodynamic-undefined-weak is passed to linker.

bfd/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* elf32-i386.c (UNDEFINED_WEAK_RESOLVED_TO_ZERO): New.
	(elf_i386_link_hash_entry): Add has_got_reloc and
	has_non_got_reloc.
	(elf_i386_link_hash_table): Add interp.
	(elf_i386_link_hash_newfunc): Initialize has_got_reloc and
	has_non_got_reloc.
	(elf_i386_copy_indirect_symbol): Copy has_got_reloc and
	has_non_got_reloc.
	(elf_i386_check_relocs): Set has_got_reloc and has_non_got_reloc.
	(elf_i386_fixup_symbol): New function.
	(elf_i386_pie_finish_undefweak_symbol): Likewise.
	(elf_i386_allocate_dynrelocs): Don't allocate space for dynamic
	relocations and discard relocations against resolved undefined
	weak symbols in executable.  Don't make resolved undefined weak
	symbols in executable dynamic.  Keep dynamic non-GOT/non-PLT
	relocation against undefined weak symbols in PIE.
	(elf_i386_size_dynamic_sections): Set interp to .interp section.
	(elf_i386_relocate_section): Don't generate dynamic relocations
	against resolved undefined weak symbols in PIE, except for
	R_386_PC32.
	(elf_i386_finish_dynamic_symbol): Keep PLT/GOT entries without
	dynamic PLT/GOT relocations for resolved undefined weak symbols.
	Don't generate dynamic relocation against resolved undefined weak
	symbol in executable.
	(elf_i386_finish_dynamic_sections): Call
	elf_i386_pie_finish_undefweak_symbol on all symbols in PIE.
	(elf_backend_fixup_symbol): New.
	* elf64-x86-64.c (UNDEFINED_WEAK_RESOLVED_TO_ZERO): New.
	(elf_x86_64_link_hash_entry): Add has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_link_hash_table): Add interp.
	(elf_x86_64_link_hash_newfunc): Initialize has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_copy_indirect_symbol): Copy has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_check_relocs): Set has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_fixup_symbol): New function.
	(elf_x86_64_pie_finish_undefweak_symbol): Likewise.
	(elf_x86_64_allocate_dynrelocs): Don't allocate space for dynamic
	relocations and discard relocations against resolved undefined
	weak symbols in executable.  Don't make resolved undefined weak
	symbols in executable dynamic.
	(elf_x86_64_size_dynamic_sections): Set interp to .interp section.
	(elf_x86_64_relocate_section): Check relocation overflow for
	dynamic relocations against unresolved weak undefined symbols.
	Don't generate dynamic relocations against resolved weak
	undefined symbols in PIE.
	(elf_x86_64_finish_dynamic_symbol): Keep PLT/GOT entries without
	dynamic PLT/GOT relocations for resolved undefined weak symbols.
	Don't generate dynamic relocation against resolved undefined weak
	symbol in executable.
	(elf_x86_64_finish_dynamic_sections): Call
	elf_x86_64_pie_finish_undefweak_symbol on all symbols in PIE.
	(elf_backend_fixup_symbol): New.

include/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* bfdlink.h (bfd_link_info): Add dynamic_undefined_weak.

ld/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* Makefile.am (ELF_X86_DEPS): Add dynamic_undefined_weak.sh.
	* Makefile.in: Regenerated.
	* NEWS: Mention -z nodynamic-undefined-weak.
	* ld.texinfo: Document -z nodynamic-undefined-weak.
	* ldmain.c (main): Initialize dynamic_undefined_weak to -1.
	* emulparams/dynamic_undefined_weak.sh: New file.
	* emulparams/elf32_x86_64.sh: Source dynamic_undefined_weak.sh.
	* emulparams/elf_i386.sh: Likewise.
	* emulparams/elf_i386_be.sh: Likewise.
	* emulparams/elf_i386_chaos.sh: Likewise.
	* emulparams/elf_i386_ldso.sh: Likewise.
	* emulparams/elf_i386_vxworks.sh: Likewise.
	* emulparams/elf_iamcu.sh: Likewise.
	* emulparams/elf_k1om.sh: Likewise.
	* emulparams/elf_l1om.sh: Likewise.
	* emulparams/elf_x86_64.sh: Likewise.
	* emulparams/extern_protected_data.sh (PARSE_AND_LIST_OPTIONS):
	Append.
	(PARSE_AND_LIST_ARGS_CASE_Z): Likewise.
	* testsuite/ld-elf/pr19719a.c: New file.
	* testsuite/ld-elf/pr19719b.c: Likewise.
	* testsuite/ld-elf/pr19719c.c: Likewise.
	* testsuite/ld-elf/pr19719d.c: Likewise.
	* testsuite/ld-i386/pr19636-1.s: Likewise.
	* testsuite/ld-i386/pr19636-1a.d: Likewise.
	* testsuite/ld-i386/pr19636-1b.d: Likewise.
	* testsuite/ld-i386/pr19636-1c.d: Likewise.
	* testsuite/ld-i386/pr19636-1d-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-1d.d: Likewise.
	* testsuite/ld-i386/pr19636-1e.d: Likewise.
	* testsuite/ld-i386/pr19636-1f.d: Likewise.
	* testsuite/ld-i386/pr19636-1g.d: Likewise.
	* testsuite/ld-i386/pr19636-1h.d: Likewise.
	* testsuite/ld-i386/pr19636-1i.d: Likewise.
	* testsuite/ld-i386/pr19636-2.s: Likewise.
	* testsuite/ld-i386/pr19636-2a.d: Likewise.
	* testsuite/ld-i386/pr19636-2b.d: Likewise.
	* testsuite/ld-i386/pr19636-2c-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2c.d: Likewise.
	* testsuite/ld-i386/pr19636-2d-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2d.d: Likewise.
	* testsuite/ld-i386/pr19636-2e-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2e.d: Likewise.
	* testsuite/ld-i386/pr19636-3.s: Likewise.
	* testsuite/ld-i386/pr19636-3a.d: Likewise.
	* testsuite/ld-i386/pr19636-3b.d: Likewise.
	* testsuite/ld-i386/pr19636-3c.d: Likewise.
	* testsuite/ld-i386/pr19636-3d.d: Likewise.
	* testsuite/ld-i386/pr19636-3e.d: Likewise.
	* testsuite/ld-i386/pr19636-3f.d: Likewise.
	* testsuite/ld-i386/pr19636-3g.d: Likewise.
	* testsuite/ld-i386/pr19636-4.s: Likewise.
	* testsuite/ld-i386/pr19636-4a.d: Likewise.
	* testsuite/ld-i386/pr19636-4b.d: Likewise.
	* testsuite/ld-i386/pr19636-4c.d: Likewise.
	* testsuite/ld-i386/pr19636-4d.d: Likewise.
	* testsuite/ld-i386/pr19704.out: Likewise.
	* testsuite/ld-i386/pr19704a.c: Likewise.
	* testsuite/ld-i386/pr19704b.c: Likewise.
	* testsuite/ld-x86-64/pr19636-1.s: Likewise.
	* testsuite/ld-x86-64/pr19636-1a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1d.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1e.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1f.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1g.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2.s: Likewise.
	* testsuite/ld-x86-64/pr19636-2a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2d-nacl.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2d.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2e.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2f.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2g.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2h.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2i.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3.s: Likewise.
	* testsuite/ld-x86-64/pr19636-3a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3d.d: Likewise.
	* testsuite/ld-x86-64/pr19704.out: Likewise.
	* testsuite/ld-x86-64/pr19704a.c: Likewise.
	* testsuite/ld-x86-64/pr19704b.c: Likewise.
	* testsuite/ld-elf/shared.exp (mix_pic_and_non_pic): New.
	Run mix_pic_and_non_pic.
	* testsuite/ld-i386/i386.exp (undefined_weak): New.
	Run undefined_weak and PR ld/19636 tests.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-x86-64/pr13082-3b.d: Updated.
	* testsuite/ld-x86-64/pr13082-4b.d: Likewise.
2016-02-26 04:55:57 -08:00
..
emulparams [x86] Resolve non-PIC undefweak symbols in executable 2016-02-26 04:55:57 -08:00
emultempl MIPS/LD: Convert ELF linker emulation option macros to an enum 2016-01-04 23:35:03 +00:00
po Copyright update for binutils 2016-01-01 23:00:01 +10:30
scripttempl Prevent .noinit section from incorrect placement for AVR. 2016-01-25 22:33:25 +03:00
testsuite [x86] Resolve non-PIC undefweak symbols in executable 2016-02-26 04:55:57 -08:00
.gitignore
aclocal.m4
ChangeLog [x86] Resolve non-PIC undefweak symbols in executable 2016-02-26 04:55:57 -08:00
ChangeLog-0001
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 Replace == with = in ld/configure.ac 2016-01-29 07:49:18 -08:00
configure.ac Replace == with = in ld/configure.ac 2016-01-29 07:49:18 -08:00
configure.host Copyright update for binutils 2016-01-01 23:00:01 +10:30
configure.tgt Copyright update for binutils 2016-01-01 23:00:01 +10:30
deffile.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
deffilep.y Copyright update for binutils 2016-01-01 23:00:01 +10:30
dep-in.sed
elf-hints-local.h
fdl.texi
gen-doc.texi Copyright update for binutils 2016-01-01 23:00:01 +10:30
genscrba.sh
genscripts.sh Copyright update for binutils 2016-01-01 23:00:01 +10:30
h8-doc.texi Copyright update for binutils 2016-01-01 23:00:01 +10:30
ld.h Remove unused field from ld_config_type structure. 2016-02-25 10:33:29 +00:00
ld.texinfo [x86] Resolve non-PIC undefweak symbols in executable 2016-02-26 04:55:57 -08:00
ldbuildid.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldbuildid.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldcref.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldctor.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldctor.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldemul.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldemul.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldexp.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldexp.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldfile.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldfile.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldgram.y Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldint.texinfo Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldlang.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldlang.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldlex-wrapper.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldlex.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldlex.l Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldmain.c [x86] Resolve non-PIC undefweak symbols in executable 2016-02-26 04:55:57 -08:00
ldmain.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldmisc.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldmisc.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldver.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldver.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldwrite.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
ldwrite.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
lexsup.c Enable -Bsymbolic and -Bsymbolic-functions to PIE 2016-02-11 15:20:13 -08:00
MAINTAINERS Copyright update for binutils 2016-01-01 23:00:01 +10:30
Makefile.am [x86] Resolve non-PIC undefweak symbols in executable 2016-02-26 04:55:57 -08:00
Makefile.in [x86] Resolve non-PIC undefweak symbols in executable 2016-02-26 04:55:57 -08:00
mri.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
mri.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
NEWS [x86] Resolve non-PIC undefweak symbols in executable 2016-02-26 04:55:57 -08:00
pe-dll.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
pe-dll.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
pep-dll.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
pep-dll.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
plugin.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
plugin.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
README Copyright update for binutils 2016-01-01 23:00:01 +10:30
stamp-h.in
sysdep.h Copyright update for binutils 2016-01-01 23:00:01 +10:30
testplug2.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
testplug3.c Copyright update for binutils 2016-01-01 23:00:01 +10:30
testplug.c Copyright update for binutils 2016-01-01 23:00:01 +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) 2012-2016 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.