binutils-gdb/ld
Alan Modra 165f707ac8 PR22471, undefined reference to linker-defined symbols
This patch processes linker script assignment statements before ld
opens DT_NEEDED libraries, in order to define symbols like __bss_start
that might also be defined by a library, falsely triggering an error
about "DSO missing from command line".

The initial value won't be correct when assigning a symbol from dot,
and I make no attempt to handle all expressions.  For example, an
assignment like "_start_foo = ADDR (.foo)" isn't valid until sections
are laid out, so won't define _start_foo early.  What's here should be
enough for most common scripts, and hopefully won't perturb fragile
scripts.

bfd/
	PR 22471
	* elflink.c (_bfd_elf_merge_symbol): Allow weak symbols to override
	early passes over linker script symbols.
	* linker.c (_bfd_generic_link_add_one_symbol): Allow symbols to
	override early passes over linker script symbols.  Clear ldscript_def
	on symbol definitions.
ld/
	PR 22471
	* ldexp.c (struct definedness_hash_entry): Delete "by_script".  Make
	"iteration" an 8-bit field, and update mask in all uses.
	(definedness_newfunc): Don't init "by_script".
	(update_definedness): Test ldscript_def rather than by_script.
	(is_sym_value): Likewise.
	(fold_name <DEFINED>): Return a result for first phase.  Test
	ldscript_def.
	(fold_name <NAME>): Return a result for first phase.
	* ldlang.c (open_input_bfds): Process all assignments, not just
	defsym.
	(lang_process): Increment lang_statement_iteration before
	open_input_bfds.
	* testsuite/ld-mips-elf/tlsdyn-o32-1.d: Adjust for larger .dynsym.
	* testsuite/ld-mips-elf/tlsdyn-o32-1.got: Likewise.
	* testsuite/ld-mips-elf/tlsdyn-o32-2.d: Likewise.
	* testsuite/ld-mips-elf/tlsdyn-o32-2.got: Likewise.
	* testsuite/ld-mips-elf/tlsdyn-o32-3.d: Likewise.
	* testsuite/ld-mips-elf/tlsdyn-o32-3.got: Likewise.
2017-11-28 22:57:00 +10:30
..
emulparams ld: Add OTHER_PLT_SECTIONS 2017-11-12 07:25:36 -08:00
emultempl Stop the v850 linker from converting to other output formats whilst linking. 2017-11-21 14:15:51 +00:00
po ld whitespace fixes 2017-10-12 23:30:43 +10:30
scripttempl ld: Add OTHER_PLT_SECTIONS 2017-11-12 07:25:36 -08:00
testsuite PR22471, undefined reference to linker-defined symbols 2017-11-28 22:57:00 +10:30
.gitignore
aclocal.m4
ChangeLog PR22471, undefined reference to linker-defined symbols 2017-11-28 22:57:00 +10:30
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-2016
ChangeLog-9197
ChangeLog-9899
config.in
configure ld whitespace fixes 2017-10-12 23:30:43 +10:30
configure.ac ld whitespace fixes 2017-10-12 23:30:43 +10:30
configure.host
configure.tgt i386: Don't add elf32_x86_64 to supported emulations 2017-10-23 14:44:04 -07:00
deffile.h
deffilep.y ld whitespace fixes 2017-10-12 23:30:43 +10:30
dep-in.sed
elf-hints-local.h
fdl.texi
gen-doc.texi
genscrba.sh
genscripts.sh ld whitespace fixes 2017-10-12 23:30:43 +10:30
h8-doc.texi
ld.h ngettext support 2017-11-07 15:52:52 +10:30
ld.texinfo ld: Correct -z ibt documentation 2017-10-25 08:44:54 -07:00
ldbuildid.c
ldbuildid.h
ldcref.c ld internationalization fixes 2017-10-11 15:04:59 +10:30
ldctor.c
ldctor.h
ldemul.c ELF: Call check_relocs after opening all inputs 2017-10-16 03:50:13 -07:00
ldemul.h ELF: Call check_relocs after opening all inputs 2017-10-16 03:50:13 -07:00
ldexp.c PR22471, undefined reference to linker-defined symbols 2017-11-28 22:57:00 +10:30
ldexp.h Copying symbol type in ld script assignments 2017-11-28 22:56:59 +10:30
ldfile.c
ldfile.h
ldgram.y ld whitespace fixes 2017-10-12 23:30:43 +10:30
ldint.texinfo
ldlang.c PR22471, undefined reference to linker-defined symbols 2017-11-28 22:57:00 +10:30
ldlang.h
ldlex-wrapper.c
ldlex.h
ldlex.l ld whitespace fixes 2017-10-12 23:30:43 +10:30
ldmain.c ld internationalization fixes 2017-10-11 15:04:59 +10:30
ldmain.h
ldmisc.c ld einfo positional arg support 2017-11-15 13:35:03 +10:30
ldmisc.h
ldver.c
ldver.h
ldwrite.c
ldwrite.h
lexsup.c ld whitespace fixes 2017-10-12 23:30:43 +10:30
MAINTAINERS
Makefile.am Correct ld/Makefile earmelfb_fuchsia dependencies 2017-10-10 14:44:58 +10:30
Makefile.in Correct ld/Makefile earmelfb_fuchsia dependencies 2017-10-10 14:44:58 +10:30
mri.c
mri.h
NEWS ld whitespace fixes 2017-10-12 23:30:43 +10:30
pe-dll.c Add libmsvcrt, libmsvcrt-os and libucrtbase to the list of libraries for which the automatic generation of exported variables should be disabled. 2017-11-23 12:07:24 +00:00
pe-dll.h
pep-dll.c
pep-dll.h
plugin.c ld whitespace fixes 2017-10-12 23:30:43 +10:30
plugin.h
README
stamp-h.in
sysdep.h
testplug2.c
testplug3.c
testplug4.c
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) 2012-2017 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.