glibc/sysdeps/unix/sysv/linux/aarch64
Szabolcs Nagy 397c54c1af 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.
2018-07-06 15:58:16 +01:00
..
bits Add AArch64 hwcap values from Linux 4.17. 2018-06-05 15:51:12 +00:00
sys Add PTRACE_SECCOMP_GET_METADATA from Linux 4.16 to sys/ptrace.h. 2018-04-24 12:11:35 +00:00
__read_tp.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
c++-types.data AArch64: Consolidate nptl/ subdirectories under linux/... 2014-06-26 09:29:24 -07:00
clone.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
configure LIBC_SLIBDIR_RTLDDIR: substitute arguments in single quotes 2018-01-25 17:20:28 +01:00
configure.ac Refactor handling of /lib64 etc. cases, move out of sysdeps/gnu/configure.ac. 2014-07-17 14:35:48 +00:00
cpu-features.c aarch64: Remove HWCAP_CPUID from HWCAP_IMPORTANT 2018-07-06 15:57:18 +01:00
cpu-features.h aarch64: add HXT Phecda core memory operation ifuncs 2018-06-12 21:29:11 +05:30
dl-cache.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
dl-procinfo.c Add AArch64 hwcap values from Linux 4.17. 2018-06-05 15:51:12 +00:00
dl-procinfo.h aarch64: add HWCAP_ATOMICS to HWCAP_IMPORTANT 2018-07-06 15:58:16 +01:00
dl-static.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
getcontext.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
gettimeofday.c aarch64: Use an ifunc/VDSO to implement gettimeofday in shared glibc. 2018-06-14 13:56:57 +01:00
Implies NPTL is no longer an add-on! 2014-07-07 09:29:06 -07:00
init-first.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
ioctl.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
ipc_priv.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
jmp_buf-macros.h Add jmp_buf-macros.h 2017-11-09 05:10:03 -08:00
kernel_rt_sigframe.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
kernel-features.h Refactor Linux ARCH_FORK implementation 2018-03-07 17:39:40 -03:00
ld.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
ldconfig.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
ldsodefs.h Remove tilegx port. 2018-04-27 19:11:24 +00:00
libanl.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libBrokenLocale.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libc-__read_tp.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
libc-start.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
libc-vdso.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
libc.abilist Add renameat2 function [BZ #17662] 2018-07-05 19:00:10 +02:00
libcrypt.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libdl.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libm.abilist Add narrowing divide functions. 2018-05-17 00:40:52 +00:00
libnsl.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libpthread.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libresolv.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
librt.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libthread_db.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
libutil.abilist Ignore absolute symbols in ABI tests. 2018-05-04 15:46:32 +00:00
localplt.data ld.so: Introduce struct dl_exception 2017-08-10 16:54:57 +02:00
makecontext.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Makefile Remove abi-*-options compiler flags 2017-08-28 17:16:53 +02:00
profil-counter.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
pt-vfork.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
readelflib.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
setcontext.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
shlib-versions Remove configuration name patterns from shlib-versions. 2014-09-12 12:28:47 +00:00
sigaction.c linux: Consolidate sigaction implementation 2018-04-05 17:09:50 -03:00
sigcontextinfo.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
swapcontext.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
syscall.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
sysconf.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
sysdep.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
sysdep.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
ucontext_i.sym aarch64: Revert the change of the __reserved member of mcontext_t 2018-01-24 11:53:30 +00:00
ucontext-internal.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Versions Revert {send,sendm,recv,recvm}msg conformance changes 2016-06-10 11:58:16 -03:00
vfork.S Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00