glibc/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h

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/* Processor capability information handling macros - aarch64 version.
Copyright (C) 2017-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
Prefer https to http for gnu.org and fsf.org URLs Also, change sources.redhat.com to sourceware.org. This patch was automatically generated by running the following shell script, which uses GNU sed, and which avoids modifying files imported from upstream: sed -ri ' s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g ' \ $(find $(git ls-files) -prune -type f \ ! -name '*.po' \ ! -name 'ChangeLog*' \ ! -path COPYING ! -path COPYING.LIB \ ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \ ! -path manual/texinfo.tex ! -path scripts/config.guess \ ! -path scripts/config.sub ! -path scripts/install-sh \ ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \ ! -path INSTALL ! -path locale/programs/charmap-kw.h \ ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \ ! '(' -name configure \ -execdir test -f configure.ac -o -f configure.in ';' ')' \ ! '(' -name preconfigure \ -execdir test -f preconfigure.ac ';' ')' \ -print) and then by running 'make dist-prepare' to regenerate files built from the altered files, and then executing the following to cleanup: chmod a+x sysdeps/unix/sysv/linux/riscv/configure # Omit irrelevant whitespace and comment-only changes, # perhaps from a slightly-different Autoconf version. git checkout -f \ sysdeps/csky/configure \ sysdeps/hppa/configure \ sysdeps/riscv/configure \ sysdeps/unix/sysv/linux/csky/configure # Omit changes that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines git checkout -f \ sysdeps/powerpc/powerpc64/ppc-mcount.S \ sysdeps/unix/sysv/linux/s390/s390-64/syscall.S # Omit change that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
2019-09-07 05:40:42 +00:00
<https://www.gnu.org/licenses/>. */
#ifndef _DL_PROCINFO_H
#define _DL_PROCINFO_H 1
#include <sys/auxv.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <sysdep.h>
/* We cannot provide a general printing function. */
#define _dl_procinfo(type, word) -1
/* No additional library search paths. */
aarch64: add HWCAP_ATOMICS to HWCAP_IMPORTANT This enables searching shared libraries in atomics/ when the hardware supports LSE atomics of armv8.1 so one can provide optimized variants of libraries in a portable way. LSE atomics does not affect library abi, the new instructions can interoperate with old ones. I considered the earlier comments on the patch https://sourceware.org/ml/libc-alpha/2018-04/msg00400.html https://sourceware.org/ml/libc-alpha/2018-04/msg00625.html It turns out that the way glibc dynamic linker decides on the search path is not very flexible: it wants to use hwcap bits and associated strings. So some targets reuse hwcap bits for glibc internal purposes to affect the search logic. But hwcap is an interface with the kernel, glibc should not allocate bits in it for its internal logic as that limits future hwcap extensions and confusing to users who expect to see hwcap bits in ifunc resolvers. Instead of rewriting the dynamic linker path logic (which affects all targets) this patch just uses the existing mechanism, however this means that the path name has to be the hwcap name "atomics" and cannot be changed to something more meaningful to users. It is hard to tell how much performance benefit this can give, in principle armv8.1 atomics can be better optimized in the hardware, so it can make a difference for synchronization heavy code. On some systems such multilib setup may be the only viable way to get optimized libraries used. * sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h (HWCAP_IMPORTANT): Add HWCAP_ATOMICS.
2018-06-28 14:30:32 +00:00
#define HWCAP_IMPORTANT HWCAP_ATOMICS
static inline const char *
__attribute__ ((unused))
_dl_hwcap_string (int idx)
{
return (unsigned)idx < _DL_HWCAP_COUNT ? GLRO(dl_aarch64_cap_flags)[idx] : "";
};
static inline int
__attribute__ ((unused))
_dl_string_hwcap (const char *str)
{
for (int i = 0; i < _DL_HWCAP_COUNT; i++)
{
if (strcmp (str, _dl_hwcap_string (i)) == 0)
return i;
}
return -1;
};
/* There're no platforms to filter out. */
#define _DL_HWCAP_PLATFORM 0
#define _dl_string_platform(str) (-1)
#endif /* dl-procinfo.h */