It has been a long practice for software using IEEE 754 floating-point
arithmetic run on MIPS processors to use an encoding of Not-a-Number
(NaN) data different to one used by software run on other processors.
And as of IEEE 754-2008 revision [1] this encoding does not follow one
recommended in the standard, as specified in section 6.2.1, where it
is stated that quiet NaNs should have the first bit (d1) of their
significand set to 1 while signalling NaNs should have that bit set to
0, but MIPS software interprets the two bits in the opposite manner.
As from revision 3.50 [2][3] the MIPS Architecture provides for
processors that support the IEEE 754-2008 preferred NaN encoding format.
As the two formats (further referred to as "legacy NaN" and "2008 NaN")
are incompatible to each other, tools have to provide support for the
two formats to help people avoid using incompatible binary modules.
The change is comprised of two functional groups of features, both of
which are required for correct support.
1. Dynamic linker support.
To enforce the NaN encoding requirement in dynamic linking a new ELF
file header flag has been defined. This flag is set for 2008-NaN
shared modules and executables and clear for legacy-NaN ones. The
dynamic linker silently ignores any incompatible modules it
encounters in dependency processing.
To avoid unnecessary processing of incompatible modules in the
presence of a shared module cache, a set of new cache flags has been
defined to mark 2008-NaN modules for the three ABIs supported.
Changes to sysdeps/unix/sysv/linux/mips/readelflib.c have been made
following an earlier code quality suggestion made here:
http://sourceware.org/ml/libc-ports/2009-03/msg00036.html
and are therefore a little bit more extensive than the minimum
required.
Finally a new name has been defined for the dynamic linker so that
2008-NaN and legacy-NaN binaries can coexist on a single system that
supports dual-mode operation and that a legacy dynamic linker that
does not support verifying the 2008-NaN ELF file header flag is not
chosen to interpret a 2008-NaN binary by accident.
2. Floating environment support.
IEEE 754-2008 features are controlled in the Floating-Point Control
and Status (FCSR) register and updates are needed to floating
environment support so that the 2008-NaN flag is set correctly and
the kernel default, inferred from the 2008-NaN ELF file header flag
at the time an executable is loaded, respected.
As the NaN encoding format is a property of GCC code generation that is
both a user-selected GCC configuration default and can be overridden
with GCC options, code that needs to know what NaN encoding standard it
has been configured for checks for the __mips_nan2008 macro that is
defined internally by GCC whenever the 2008-NaN mode has been selected.
This mode is determined at the glibc configuration time and therefore a
few consistency checks have been added to catch cases where compilation
flags have been overridden by the user.
The 2008 NaN set of features relies on kernel support as the in-kernel
floating-point emulator needs to be aware of the NaN encoding used even
on hard-float processors and configure the FPU context according to the
value of the 2008 NaN ELF file header flag of the executable being
started. As at this time work on kernel support is still in progress
and the relevant changes have not made their way yet to linux.org master
repository.
Therefore the minimum version supported has been artificially set to
10.0.0 so that 2008-NaN code is not accidentally run on a Linux kernel
that does not suppport it. It is anticipated that the version is
adjusted later on to the actual initial linux.org kernel version to
support this feature. Legacy NaN encoding support is unaffected, older
kernel versions remain supported.
[1] "IEEE Standard for Floating-Point Arithmetic", IEEE Computer
Society, IEEE Std 754-2008, 29 August 2008
[2] "MIPS Architecture For Programmers, Volume I-A: Introduction to the
MIPS32 Architecture", MIPS Technologies, Inc., Document Number:
MD00082, Revision 3.50, September 20, 2012
[3] "MIPS Architecture For Programmers, Volume I-A: Introduction to the
MIPS64 Architecture", MIPS Technologies, Inc., Document Number:
MD00083, Revision 3.50, September 20, 2012
These prototypes are duplicated in many places. Add a dedicated
header for holding prototypes for program-specific functions to
avoid that.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
ARM now supports loading unmarked objects from
the dynamic loader cache. Unmarked objects can
be used with the hard-float or soft-float ABI.
We must support loading unmarked objects during
the transition period from a binutils that does
not mark objects to one that does mark them with
the correct ELF flags.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
* sysdeps/generic/ldconfig.h (FLAG_AARCH64_LIB64): New macro.
* elf/cache.c (print_entry): Print ",AArch64" for
FLAG_AARCH64_LIB64.
Signed-off-by: Steve McIntyre <steve.mcintyre@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@systemhalted.org>
* sysdeps/generic/ldconfig.h (FLAG_ARM_LIBHF): New macro.
* elf/cache.c (print_entry): Print ",hard-float" for
FLAG_ARM_LIBHF.
Signed-off-by: Steve McIntyre <steve.mcintyre@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@systemhalted.org>
* elf/cache.c (print_entry): Add case for FLAG_POWERPC_LIB64.
Remove per-machine conditionals for FLAG_* cases.
* sysdeps/unix/sysv/linux/powerpc/ldconfig.h: New file.
* sysdeps/unix/sysv/linux/powerpc/readelflib.c: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/dl-cache.h: New file.
2001-07-06 Paul Eggert <eggert@twinsun.com>
* manual/argp.texi: Remove ignored LGPL copyright notice; it's
not appropriate for documentation anyway.
* manual/libc-texinfo.sh: "Library General Public License" ->
"Lesser General Public License".
2001-07-06 Andreas Jaeger <aj@suse.de>
* All files under GPL/LGPL version 2: Place under LGPL version
2.1.
* elf/cache.c: Mark and have translated a few more messages.
2001-03-19 Martin Schwidefsky <schwidefsky@de.ibm.com>
* elf/cache.c: Add case for FLAG_S390_LIB64.
* sysdeps/generic/ldconfig.h: Add define for FLAG_S390_LIB64.
* sysdeps/unix/sysv/linux/s390/ldconfig.h: New file.
* sysdeps/unix/sysv/linux/s390/readelflib.c: New file.
2001-03-19 Ulrich Drepper <drepper@redhat.com>
2001-03-12 Jakub Jelinek <jakub@redhat.com>
* csu/Makefile (abi-tag.h): Define OS and version separately, allow
version to be overriden from config.h.
* csu/abi-note.S: Use OS and version separately, include config.h.
* elf/dl-load.c (_dl_osversion): New.
(_dl_map_object_from_fd): Kill some warnings.
(open_verify): Check .note.ABI-tag of the library if present.
* elf/Makefile (CPPFLAGS-dl-load.c): Add -I$(csu-objpfx).
* elf/cache.c (struct cache_entry): Add osversion.
(print_entry): Print osversion.
(print_cache): Pass osversion to it.
(compare): Sort according to osversion.
(save_cache): Set osversion.
(add_to_cache): Add osversion argument.
* sysdeps/generic/ldconfig.h (add_to_cache, process_file,
process_elf_file): Add osversion argument.
* elf/readlib.c (process_file): Likewise.
* sysdeps/generic/readelflib.c (process_elf_file): Likewise.
* sysdeps/unix/sysv/linux/ia64/readelflib.c (process_elf_file,
process_elf32_file, process_elf64_file): Likewise.
* sysdeps/unix/sysv/linux/i386/readelflib.c (process_elf_file,
process_elf32_file, process_elf64_file): Likewise.
* sysdeps/unix/sysv/linux/sparc/readelflib.c (process_elf_file,
process_elf32_file, process_elf64_file): Likewise.
* elf/ldconfig.c (manual_link): Pass it.
(search_dir): Issue diagnostic if two libs with the same soname in
the same directory have different .note.ABI-tag. Record osversion in
dlib_entry and use it from there.
(struct lib_entry): Remove.
(struct dlib_entry): Add osversion.
* sysdeps/generic/dl-cache.c (_dl_load_cache_lookup): Check
osversion.
* sysdeps/generic/dl-cache.h (struct file_entry_new): Replace __unused
field with osversion.
* sysdeps/generic/ldsodefs.h (_dl_osversion): Declare.
* sysdeps/unix/sysv/linux/init-first.c: Include ldsodefs.h.
* sysdeps/unix/sysv/linux/dl-osinfo.h (DL_SYSDEP_OSCHECK): Save kernel
version in _dl_osversion.
* sysdeps/unix/sysv/linux/configure.in: Define __ABI_TAG_VERSION.
* Makerules (build-shlib-helper, build-module-helper): New.
(build-shlib, build-module-helper): Make sure .note.ABI-tag comes
early.
* config.h.in (__ABI_TAG_VERSION): Add.
* elf/dl-minimal.c (__strtoul_internal): Set endptr on return.
* sysdeps/unix/sysv/linux/i386/dl-librecon.h (EXTRA_LD_ENVVARS):
Handle LD_ASSUME_KERNEL.
* sysdeps/unix/sysv/linux/dl-librecon.h: New.
2001-03-07 David Mosberger <davidm@hpl.hp.com>
* sysdeps/ia64/bits/fenv.h (FE_NONIEEE_ENV): New macro.
2001-03-07 Jes Sorensen <jes@linuxcare.com>
* sysdeps/unix/sysv/linux/ia64/ioperm.c (_ioperm): Remove unused
variables addr & len.
2001-02-22 Jes Sorensen <jes@linuxcare.com>
* sysdeps/ia64/fpu/feenablxcpt.c (feenableexcept): Remove
punctuation in asm constraint.
2001-03-07 Mark Kettenis <kettenis@gnu.org>
* resolv/netdb.h [__USE_GNU]: Define __need_timespec and include
<time.h> to get definition of `struct timespec'.
2001-03-08 Jakub Jelinek <jakub@redhat.com>
* elf/rtld.c (dl_main): If tracing, warn about undefined symbols if
LD_WARN=1, not if LD_WARN is unset.
2001-03-07 Andreas Schwab <schwab@suse.de>
* elf/ldconfig.h: Moved to ...
* sysdeps/generic/ldconfig.h: ... here.
* sysdeps/unix/sysv/linux/i386/ldconfig.h: New file.
* sysdeps/unix/sysv/linux/m68k/ldconfig.h: New file.
* sysdeps/unix/sysv/linux/ia64/ldconfig.h: New file.
* elf/readlib.c (interpreters, known_libs): Use
SYSDEP_KNOWN_INTERPRETER_NAMES and SYSDEP_KNOWN_LIBRARY_NAMES
instead of hard coding old names.
