forked from Imagelibrary/binutils-gdb
13a3cad698
normally RELA relocs in BFD should not consider the contents of the relocated place. The aarch64 psABI is even stricter, it specifies (section 5.7.16) that all RELA relocs _must_ be idempotent. Since the inception of the aarch64 BFD backend all the relocs have a non-zero src_mask, and hence break this invariant. It's normally not a very visible problem as one can see it only when the relocated place already contains a non-zero value, which usually only happens sometimes when using 'ld -r' (or as in the testcase when jumping through hoops to generate the relocations). Or with alternative toolchains that do encode stuff in the relocated places with the assumption that a relocation to that place ignores whatever is there (as they can according to the psABI). Golang is such a toolchain and https://github.com/golang/go/issues/39927 is ultimately caused by this problem: the testcase testGCData failing is caused by the garbage collection data-structure to describe a type containing pointers to be wrong. It's wrong because a field that's supposed to contain a file-relative offset (to some gcbits) has a relocation applied and that relocation has an addend which also is already part of the go-produced object file (so the addend is implicitely applied twice). bfd/ PR ld/30437 * elfnn-aarch64.c (elfNN_aarch64_howto_table): Clear src_mask if all relocation descriptors. ld/ * testsuite/ld-aarch64/rela-idempotent.s: New testcase. * testsuite/ld-aarch64/rela-idempotent.d: New. * testsuite/ld-aarch64/aarch64-elf.exp: Run it.
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) 2012-2023 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.