binutils-gdb/ld
Maciej W. Rozycki 3c7687b9cd MIPS/LD: Accept high-part relocations in PIC code with absolute symbols
Accept R_MIPS_HI16, R_MIPS_HIGHER and R_MIPS_HIGHEST relocations and
their compressed counterparts in PIC code where the symbol referred is
absolute.  Such an operation is meaningful, because an absolute symbol
effectively is a constant the calculation of the value of which has been
deferred to the static link time, and which is not going to change any
further at the dynamic load time.  Therefore there is no need ever to
refuse the use of these relocations with such symbols, as the resulting
run-time value observed by the program will be correct even in PIC code.

This is not the case with R_MIPS_26 and its compressed counterparts,
because the run-time value calculated by the instructions these
relocations are used with depends on the address of the instruction
itself, and that can change according to the base address used by the
dynamic loader.  Therefore these relocations have to continue being
rejected in PIC code even with absolute symbols.

This allows successful linking of code that relies on previous linker
behavior up to commit 861fb55ab5 ("Defer allocation of R_MIPS_REL32
GOT slots"), <https://sourceware.org/ml/binutils/2008-08/msg00096.html>,
which introduced the problematic check missing this special exception
for absolute symbols.

	bfd/
	* elfxx-mips.c (_bfd_mips_elf_check_relocs) <R_MIPS16_HI16>
	<R_MIPS_HI16, R_MIPS_HIGHER, R_MIPS_HIGHEST, R_MICROMIPS_HI16>
	<R_MICROMIPS_HIGHER, R_MICROMIPS_HIGHEST>: Also accept an
	absolute symbol in PIC code.

	ld/
	* testsuite/ld-mips-elf/pic-reloc-0.d: New test.
	* testsuite/ld-mips-elf/pic-reloc-1.d: New test.
	* testsuite/ld-mips-elf/pic-reloc-2.d: New test.
	* testsuite/ld-mips-elf/pic-reloc-3.d: New test.
	* testsuite/ld-mips-elf/pic-reloc-4.d: New test.
	* testsuite/ld-mips-elf/pic-reloc-absolute-hi.ld: New test
	linker script.
	* testsuite/ld-mips-elf/pic-reloc-absolute-lo.ld: New test
	linker script.
	* testsuite/ld-mips-elf/pic-reloc-ordinary.ld: New test linker
	script.
	* testsuite/ld-mips-elf/pic-reloc-j.s: New test source.
	* testsuite/ld-mips-elf/pic-reloc-lui.s: New test source.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.
2018-11-27 16:34:03 +00:00
..
emulparams RISC-V: Adjust __global_pointer$ value to reduce code size. 2018-10-15 16:00:28 -07:00
emultempl Andes Technology has good news for you, we plan to update the nds32 port of binutils on upstream! 2018-09-20 13:32:58 +01:00
po (Another) Updated Spanish translation for the ld subdirectory. 2018-11-16 11:36:08 +00:00
scripttempl Allow for compilers that do not produce aligned .rdat sections in PE format files. 2018-11-09 11:13:50 +00:00
testsuite MIPS/LD: Accept high-part relocations in PIC code with absolute symbols 2018-11-27 16:34:03 +00:00
.gitignore
aclocal.m4 Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
ChangeLog MIPS/LD: Accept high-part relocations in PIC code with absolute symbols 2018-11-27 16:34:03 +00:00
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-2016 ChangeLog rotation 2017-01-02 13:55:05 +10:30
ChangeLog-2017 ChangeLog rotation 2018-01-03 17:49:42 +10:30
ChangeLog-9197
ChangeLog-9899
config.in Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
configure Regenerate configure and pot files with updated binutils version number. 2018-06-24 19:13:01 +01:00
configure.ac Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
configure.host Remove m88k support 2018-04-16 15:23:38 +09:30
configure.tgt Add support for the C_SKY series of processors. 2018-07-30 12:24:14 +01:00
deffile.h Speed up direct linking with DLLs on Windows (2/2). 2018-04-04 12:13:05 +02:00
deffilep.y Speed up direct linking with DLLs on Windows (2/2). 2018-04-04 12:13:05 +02:00
dep-in.sed
elf-hints-local.h
fdl.texi
gen-doc.texi Add support for the C_SKY series of processors. 2018-07-30 12:24:14 +01:00
genscrba.sh
genscripts.sh ld: Enable using separate linker script for -z relro 2018-07-18 13:20:06 +02:00
h8-doc.texi Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
ld.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ld.texi (Another) Updated Spanish translation for the ld subdirectory. 2018-11-16 11:36:08 +00:00
ldbuildid.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldbuildid.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldcref.c ld error/warning messages 2018-02-26 10:51:12 +10:30
ldctor.c ld error/warning messages 2018-02-26 10:51:12 +10:30
ldctor.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldemul.c powerpc common-page-size 2018-04-14 17:56:40 +09:30
ldemul.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldexp.c Separate header PT_LOAD for -z separate-code 2018-10-08 20:26:08 +10:30
ldexp.h Delay evaluation of alignment expressions in output sections 2018-08-26 22:45:59 +09:30
ldfile.c ld error/warning messages 2018-02-26 10:51:12 +10:30
ldfile.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldgram.y PR23648, Symbols based on MEMORY regions confuse --gc-sections 2018-09-19 15:08:48 +09:30
ldint.texi Fix use of "command line X" in binutils doc 2018-07-02 11:18:24 +01:00
ldlang.c Report scripts and libraries searched for ld --trace 2018-10-29 18:21:05 +10:30
ldlang.h Delay evaluation of alignment expressions in output sections 2018-08-26 22:45:59 +09:30
ldlex-wrapper.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldlex.h [MicroBlaze] PIC data text relative 2018-04-17 14:47:13 -07:00
ldlex.l Update PRU assembler to corect hardware register numbering for DWARF. 2018-08-03 10:02:39 +01:00
ldmain.c LD: Convert %P: %H:' to %H:' in error messages 2018-11-27 16:34:03 +00:00
ldmain.h Report scripts and libraries searched for ld --trace 2018-10-29 18:21:05 +10:30
ldmisc.c Report scripts and libraries searched for ld --trace 2018-10-29 18:21:05 +10:30
ldmisc.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldver.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldver.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldwrite.c ld error/warning messages 2018-02-26 10:51:12 +10:30
ldwrite.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
lexsup.c Report scripts and libraries searched for ld --trace 2018-10-29 18:21:05 +10:30
MAINTAINERS Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
Makefile.am ld -r script fixes 2018-10-29 17:50:40 +10:30
Makefile.in ld -r script fixes 2018-10-29 17:50:40 +10:30
mri.c Remove m68k-aout and m68k-coff support 2018-04-16 15:31:36 +09:30
mri.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
NEWS Add support for the C_SKY series of processors. 2018-07-30 12:24:14 +01:00
pe-dll.c Remove arm-epoc-pe support 2018-04-16 20:29:05 +09:30
pe-dll.h Speed up direct linking with DLLs on Windows (1/2). 2018-04-04 12:07:50 +02:00
pep-dll.c Speed up direct linking with DLLs on Windows (1/2). 2018-04-04 12:07:50 +02:00
pep-dll.h Speed up direct linking with DLLs on Windows (1/2). 2018-04-04 12:07:50 +02:00
plugin.c ld: Set non_ir_ref_regular for --undefined SYMBOL 2018-07-04 06:29:13 -07:00
plugin.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
README Bump to autoconf 2.69 and automake 1.15.1 2018-06-19 16:55:06 -04:00
stamp-h.in
sysdep.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
testplug2.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
testplug3.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
testplug4.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
testplug.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +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.texi), as well as the
  beginnings of an internals manual (ldint.texi).

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.texi 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) 2012-2018 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.