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Under certain conditions the linker rewrites: - GOT access using lgrl to larl, changing the GOTENT to a PC32DBL reloc - GOT access using lg to larl, changing the GOT20 to a PC32DBL reloc - Relative long addressing instructions of weak symbols, which definitively resolve to zero to either (1) load address of zero, (2) a NOP, or (3) a trapping instruction, changing the relocation to a NONE reloc. Suppress rewriting of non-TLS instructions and related relocations in linker if option --no-relax is specified. This aligns with LLVM linker behavior on s390. Like x86-64 do not actually enable the linker relaxation option by default, as other targets would do using ENABLE_RELAXATION or TARGET_ENABLE_RELAXATION in their linker emulation scripts. Instead perform linker instruction/relocation rewrites by default unless linker option --no-relax is explicitly specified by the user. This ensures no functional change unless --no-relax is used. bfd/ * elf64-s390.c (elf_s390_relocate_section): Do not rewrite non-TLS instructions and related relocations if --no-relax. * elf32-s390.c (elf_s390_relocate_section): Likewise. ld/testsuite/ * ld-s390/s390.exp: New tests. Same as gotreloc_*-1a and weakundef-*a, but with linker option --no-relax, to verify suppression of linker non-TLS insn and reloc rewrites. * ld-s390/gotreloc_31-1b.dd: Likewise. * ld-s390/gotreloc_31-no-pie-1b.dd: Likewise. * ld-s390/gotreloc_64-no-pie-1b.dd: Likewise. * ld-s390/gotreloc_64-norelro-1b.dd: Likewise. * ld-s390/gotreloc_64-relro-1b.dd: Likewise. * ld-s390/weakundef-1b.d: Likewise. Check for expected reloc overflows. * ld-s390/weakundef-2b.d: Likewise. Signed-off-by: Jens Remus <jremus@linux.ibm.com>
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) 2012-2025 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.