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f0158f4416
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Alan Modra f0158f4416 PowerPC dynamic relocations 
This patch fixes a number of issues with powerpc dynamic relocations.

1) Both ppc and ppc64 were emitting more dynamic symbols and
relocations than necessary, due to not supporting static linker
resolution of tls_index entries for __tls_get_addr_opt.  This meant
that any @got@tlsgd or @got@tlsld reloc needed to make their symbols
dynamic and generate dptmod and dtprel relocs for the dynamic linker.
That would have been passable, but what happened was that practically
all @got relocations resulted in their symbols being made dynamic and
dynamic relocations emitted against the GOT entries.  (Mostly visible
on ppc32 executables since ppc64 gcc really only uses @got style
relocs for TLS.)

2) The PowerOpen syntax was not supported with __tls_get_addr_opt.
DTPMOD/DTPREL relocs on tls_index TOC entries did not use the trick of
forcing dynamic symbols and relocations so those entries always
resulted in the full __tls_get_addr processing.  gcc doesn't use the
PowerOpen syntax for TLS, and normally such code would be optimized to
TLS IE or LE so the impact of missing this support was minimal.

3) In an executable, relocations against GNU indirect functions always
used the value of their PLT stub.   While this is correct, it is
better in some cases to use a dynamic relocation.  An extra dynamic
relocation can mean that calls via function pointers need not bounce
through the PLT stub at runtime.

The patch also tidies the PLT handling code in ppc32
allocate_dynrelocs.  Allocating PLT entries after other dynamic relocs
allows the PLT loop to omit special handling for undefined weak
symbols, and that in turn allows the loop to be simplified.

bfd/
	* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Merge two cases
	where dynamic relocs are preferable.  Allow ifunc too.
	(ensure_undefweak_dynamic): New function.
	(allocate_dynrelocs): Use it here.  Move plt handling last and
	don't make symbols dynamic, simplifying loop.  Only make undef
	weak symbols with GOT entries dynamic.  Correct condition
	for GOT relocs.  Handle dynamic relocs on ifuncs.  Correct
	comments.  Remove goto.
	(ppc_elf_relocate_section): Correct test for using dynamic
	symbol on GOT relocs.  Rearrange test for emitting GOT relocs
	to suit.  Set up explicit tls_index entries and implicit GOT
	tls_index entries resolvable at link time for
	__tls_get_addr_opt.  Simplify test to clear mem for prelink.
	* elf64-ppc.c (allocate_got): Correct condition for GOT relocs.
	(ensure_undefweak_dynamic): New function.
	(allocate_dynrelocs): Use it here.  Only make undef weak symbols
	with GOT entries dynamic.  Remove unnecessary test of
	WILL_CALL_FINISH_DYNAMIC_SYMBOL in PLT handling.
	(ppc64_elf_relocate_section): Correct test for using dynamic
	symbol on GOT relocs.  Rearrange test for emitting GOT relocs
	to suit.  Set up explicit tls_index entries and implicit GOT
	tls_index entries resolvable at link time for __tls_get_addr_opt.
	Simplify expression to clear mem for prelink.
ld/
	* testsuite/ld-powerpc/tlsexe.r: Update for fewer dynamic relocs
	and symbols.
	* testsuite/ld-powerpc/tlsexe.d: Likewise.
	* testsuite/ld-powerpc/tlsexe.g: Likewise.
2017-01-24 12:15:54 +10:30
..
emulparams X32: Place .plt.got section after .plt section 2017-01-10 13:57:39 -08:00
emultempl Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
po Updated Irish translation for ld and Swedish translation for gas. 2017-01-23 13:32:12 +00:00
scripttempl Support -z relro on hppa 2017-01-02 22:42:45 +10:30
testsuite PowerPC dynamic relocations 2017-01-24 12:15:54 +10:30
.gitignore
aclocal.m4
ChangeLog PowerPC dynamic relocations 2017-01-24 12:15:54 +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 rotation 2017-01-02 13:55:05 +10:30
ChangeLog-9197
ChangeLog-9899
config.in
configure Run more ld tests when not native 2017-01-02 23:48:08 +10:30
configure.ac Run more ld tests when not native 2017-01-02 23:48:08 +10:30
configure.host Run more ld tests when not native 2017-01-02 23:48:08 +10:30
configure.tgt Add support for x86/64 redox target. 2017-01-11 15:05:53 +00:00
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 Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ld.texinfo Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
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 Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldfile.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldgram.y Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldint.texinfo Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldlang.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
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 Use noyywrap option in lex files. 2017-01-04 16:05:22 +00:00
ldlex.l Use noyywrap option in lex files. 2017-01-04 16:05:22 +00:00
ldmain.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldmain.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ldmisc.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
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 Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
MAINTAINERS Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
Makefile.am [ARC] Add new linker emulation for nps 2017-01-10 10:55:13 +00:00
Makefile.in [ARC] Add new linker emulation for nps 2017-01-10 10:55:13 +00:00
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 Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
pe-dll.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
pe-dll.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
pep-dll.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
pep-dll.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
plugin.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
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
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
testplug.c Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
TODO

README

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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.