Complement commit d345186d05 ("Check if GNU_RELRO segment is is
generated") and exclude the presence of a `.got' section from implying
the creation of a GNU_RELRO segment for targets which place the section
along with small data, and therefore as it stands cannot have the
section assigned to GNU_RELRO. This is because we currently only
support a single GNU_RELRO segment and we place it at the beginning of
regular data which is then separated from small data by read-write data.
Currently the list of such targets consists of Alpha, Linux HPPA, NetBSD
HPPA, OpenBSD HPPA, Meta, MIPS, Nios II, OpenRISC 1000, RISC-V, SH and
X86-64, as determined by examining default linker scripts produced in a
`--enable-targets=all' build for those that have DATA_SEGMENT_RELRO_END
set and `.got' placed beyond. These targets do not set NO_SMALL_DATA or
DATA_GOT in their respective files in ld/emulparams/*, hovever checking
for the absence of these settings on its own is not very feasible due to
the structure of these files and the lack of support for GNU_RELRO by
some targets in the first place.
Add a separate control for `.got.plt' which does get placed in GNU_RELRO
on MIPS targets even though `.got' does not.
ld/
* testsuite/ld-elf/binutils.exp (binutils_test): Make the
expectation for `.got' in GNU_RELRO segment target-specific.
Handle `.got.plt' separately.
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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.
927960f053