This commit doesn't affect libc.so.6, its just housekeeping to prepare
for adding explicit ISA level support.
Tested build on x86_64 and x86_32 with/without multiarch.
This commit doesn't affect libc.so.6, its just housekeeping to prepare
for adding explicit ISA level support.
Because strcmp-sse2.S implements so many functions (more from
avx2/evex/sse42) add a new file 'strcmp-naming.h' to assist in
getting the correct symbol name for all the function across
multiarch/non-multiarch builds.
Tested build on x86_64 and x86_32 with/without multiarch.
The previous macro name can be confusing given that both
`__strcasecmp_l_nonascii` and `__strcasecmp_nonascii` are
functions and we use the `_l` version.
The intrinsics are not available before GCC7 and using standard
operators generates code of equivalent or better quality.
Removed:
_cvtmask64_u64
_kshiftri_mask64
_kand_mask64
Geometric Mean of 5 Runs of Full Benchmark Suite New / Old: 0.958
These functions all have optimized versions:
__strncat_sse2_unaligned, __strncpy_sse2_unaligned, and
stpncpy_sse2_unaligned which are faster than their respective generic
implementations. Since the sse2 versions can run on baseline x86_64,
we should use these as the baseline implementation and can remove the
generic implementations.
Geometric mean of N=20 runs of the entire benchmark suite on:
11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz (Tigerlake)
__strncat_sse2_unaligned / __strncat_generic: .944
__strncpy_sse2_unaligned / __strncpy_generic: .726
__stpncpy_sse2_unaligned / __stpncpy_generic: .650
Tested build with and without multiarch and full check with multiarch.
gas -mtune= may change NOP generating patterns but -mtune=i686 has no
difference from the default by inspecting .o and .os files.
Note: Clang doesn't support -Wa,-mtune=i686.
Remove redundant strcspn-generic, strpbrk-generic and strspn-generic
from sysdep_routines in sysdeps/x86_64/multiarch/Makefile added by
commit c69f960b01
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Sun Jul 3 21:28:07 2022 -0700
x86: Add support for building str{c|p}{brk|spn} with explicit ISA level
since they have been added to sysdep_routines in sysdeps/x86_64/Makefile.
This change provides implementations for the mbrtoc8 and c8rtomb
functions adopted for C++20 via WG21 P0482R6 and for C2X via WG14
N2653. It also provides the char8_t typedef from WG14 N2653.
The mbrtoc8 and c8rtomb functions are declared in uchar.h in C2X
mode or when the _GNU_SOURCE macro or C++20 __cpp_char8_t feature
test macro is defined.
The char8_t typedef is declared in uchar.h in C2X mode or when the
_GNU_SOURCE macro is defined and the C++20 __cpp_char8_t feature
test macro is not defined (if __cpp_char8_t is defined, then char8_t
is a builtin type).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
We found that string functions were using AND+ADDP
to find the nibble/syndrome mask but there is an easier
opportunity through `SHRN dst.8b, src.8h, 4` (shift
right every 2 bytes by 4 and narrow to 1 byte) and has
same latency on all SIMD ARMv8 targets as ADDP. There
are also possible gaps for memcmp but that's for
another patch.
We see 10-20% savings for small-mid size cases (<=128)
which are primary cases for general workloads.
1. Refactor files so that all implementations are in the multiarch
directory
- Moved the implementation portion of memcmp sse2 from memcmp.S to
multiarch/memcmp-sse2.S
- The non-multiarch file now only includes one of the
implementations in the multiarch directory based on the compiled
ISA level (only used for non-multiarch builds. Otherwise we go
through the ifunc selector).
2. Add ISA level build guards to different implementations.
- I.e memcmp-avx2-movsb.S which is ISA level 3 will only build if
compiled ISA level <= 3. Otherwise there is no reason to include
it as we will always use one of the ISA level 4
implementations (memcmp-evex-movbe.S).
3. Add new multiarch/rtld-{w}memcmp{eq}.S that just include the
non-multiarch {w}memcmp{eq}.S which will in turn select the best
implementation based on the compiled ISA level.
4. Refactor the ifunc selector and ifunc implementation list to use
the ISA level aware wrapper macros that allow functions below the
compiled ISA level (with a guranteed replacement) to be skipped.
Tested with and without multiarch on x86_64 for ISA levels:
{generic, x86-64-v2, x86-64-v3, x86-64-v4}
And m32 with and without multiarch.
1. Refactor files so that all implementations are in the multiarch
directory
- Moved the implementation portion of memset sse2 from memset.S to
multiarch/memset-sse2.S
- The non-multiarch file now only includes one of the
implementations in the multiarch directory based on the compiled
ISA level (only used for non-multiarch builds. Otherwise we go
through the ifunc selector).
2. Add ISA level build guards to different implementations.
- I.e memset-avx2-unaligned-erms.S which is ISA level 3 will only
build if compiled ISA level <= 3. Otherwise there is no reason
to include it as we will always use one of the ISA level 4
implementations (memset-evex-unaligned-erms.S).
3. Add new multiarch/rtld-memset.S that just include the
non-multiarch memset.S which will in turn select the best
implementation based on the compiled ISA level.
4. Refactor the ifunc selector and ifunc implementation list to use
the ISA level aware wrapper macros that allow functions below the
compiled ISA level (with a guranteed replacement) to be skipped.
Tested with and without multiarch on x86_64 for ISA levels:
{generic, x86-64-v2, x86-64-v3, x86-64-v4}
And m32 with and without multiarch.
1. Refactor files so that all implementations are in the multiarch
directory
- Moved the implementation portion of memmove sse2 from memmove.S
to multiarch/memmove-sse2.S
- The non-multiarch file now only includes one of the
implementations in the multiarch directory based on the compiled
ISA level (only used for non-multiarch builds. Otherwise we go
through the ifunc selector).
2. Add ISA level build guards to different implementations.
- I.e memmove-avx2-unaligned-erms.S which is ISA level 3 will only
build if compiled ISA level <= 3. Otherwise there is no reason
to include it as we will always use one of the ISA level 4
implementations (memmove-evex-unaligned-erms.S).
3. Add new multiarch/rtld-memmove.S that just include the
non-multiarch memmove.S which will in turn select the best
implementation based on the compiled ISA level.
4. Refactor the ifunc selector and ifunc implementation list to use
the ISA level aware wrapper macros that allow functions below the
compiled ISA level (with a guranteed replacement) to be skipped.
Tested with and without multiarch on x86_64 for ISA levels:
{generic, x86-64-v2, x86-64-v3, x86-64-v4}
And m32 with and without multiarch.
isa raising memmove
The changes for these functions are different than the others because
the best implementation (sse4_2) requires the generic
implementation as a fallback to be built as well.
Changes are:
1. Add non-multiarch functions for str{c|p}{brk|spn}.c to statically
select the best implementation based on the configured ISA build
level.
2. Add stubs for str{c|p}{brk|spn}-generic and varshift.c to in the
sysdeps/x86_64 directory so that the the sse4 implementation will
have all of its dependencies for the non-multiarch / rtld build
when ISA level >= 2.
3. Add new multiarch/rtld-strcspn.c that just include the
non-multiarch strcspn.c which will in turn select the best
implementation based on the compiled ISA level.
4. Refactor the ifunc selector and ifunc implementation list to use
the ISA level aware wrapper macros that allow functions below the
compiled ISA level (with a guranteed replacement) to be skipped.
Tested with and without multiarch on x86_64 for ISA levels:
{generic, x86-64-v2, x86-64-v3, x86-64-v4}
And m32 with and without multiarch.
And also fixes the SINGLE_THREAD_P macro for SINGLE_THREAD_BY_GLOBAL,
since header inclusion single-thread.h is in the wrong order, the define
needs to come before including sysdeps/unix/sysdep.h. The macro
is now moved to a per-arch single-threade.h header.
The SINGLE_THREAD_P is used on some more places.
Checked on aarch64-linux-gnu and x86_64-linux-gnu.
It was added on Linux 5.12 (2a1867219c7b27f928e2545782b86daaf9ad50bd)
to allow change the properties of a mount or a mount tree using file
descriptors which the new mount api is based on.
Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The new mount API was added on Linux 5.2 with six new syscalls:
fsopen, fsconfig, fsmount, move_mount, fspick, and open_tree.
The new test verifies minimal functionality along with error paths
for specific arguments and their corner cases.
Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (a07b20004793d8926f78d63eb5980559f7813404)
to return a O_PATH-opened file descriptor to an existing mountpoint.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (cf3cba4a429be43e5527a3f78859b1bfd9ebc5fb)
that can be used to pick an existing mountpoint into an filesystem
context which can thereafter be used to reconfigure a superblock
with fsconfig syscall.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (ecdab150fddb42fe6a739335257949220033b782)
as a way to a configure filesystem creation context and trigger
actions upon it, to be used in conjunction with fsopen, fspick and
fsmount.
The fsconfig_command commands are currently only defined as an enum,
so they can't be checked on tst-mount-consts.py with current test
support.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The AFP feature (Alternate floating-point behavior) was added in armv8.7 and
introduced new FPCR bits.
Currently, HWCAP2_AFP bits (bit 0, 1, 2) in FPCR are preserved when fenv is
set to default environment. This is a deviation from standard behaviour.
Clear these bits when setting the fenv to default.
There is no libc API to modify the new FPCR bits. Restoring those bits matters
if the user changed them directly.
The main drive is to optimize the internal usage and required size
when sigset_t is embedded in other data structures. On Linux, the
current supported signal set requires up to 8 bytes (16 on mips),
was lower than the user defined sigset_t (128 bytes).
A new internal type internal_sigset_t is added, along with the
functions to operate on it similar to the ones for sigset_t. The
internal-signals.h is also refactored to remove unused functions
Besides small stack usage on some functions (posix_spawn, abort)
it lower the struct pthread by about 120 bytes (112 on mips).
Checked on x86_64-linux-gnu.
Reviewed-by: Arjun Shankar <arjun@redhat.com>
The new asymmetric mode is available when HWCAP2_MTE3 is set (support is
available), bit2 is set in the tunable (user request per application),
and the system is configured such that the asymmetric mode is preferred over
sync or async (per-cpu system-wide setting).
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
On success, mq_receive() and mq_timedreceive() return the number of
bytes in the received message, so it requires to check if the value
is larger than 0.
Checked on i686-linux-gnu.
Was missing to for the multiarch build rtld-strncmp-sse4_2.os was
being built and exporting symbols:
build/glibc/string/rtld-strncmp-sse4_2.os:
0000000000000000 T __strncmp_sse42
Introduced in:
commit 11ffcacb64
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Wed Jun 21 12:10:50 2017 -0700
x86-64: Implement strcmp family IFUNC selectors in C
Was missing to for the multiarch build rtld-strcspn-sse4.os was
being built and exporting symbols:
build/glibc/string/rtld-strcspn-sse4.os:
U ___m128i_shift_right
U __strcspn_generic
0000000000000000 T __strcspn_sse42
U strlen
build/glibc/string/rtld-varshift.os:
0000000000000000 R ___m128i_shift_right
Introduced in:
commit 06e51c8f3d
Author: H.J. Lu <hongjiu.lu@intel.com>
Date: Fri Jul 3 02:48:56 2009 -0700
Add SSE4.2 support for strcspn, strpbrk, and strspn on x86-64.
Was missing to for the multiarch build rtld-memmove-ssse3.os was
being built and exporting symbols:
>$ nm string/rtld-memmove-ssse3.os
U __GI___chk_fail
0000000000000020 T __memcpy_chk_ssse3
0000000000000040 T __memcpy_ssse3
0000000000000020 T __memmove_chk_ssse3
0000000000000040 T __memmove_ssse3
0000000000000000 T __mempcpy_chk_ssse3
0000000000000010 T __mempcpy_ssse3
U __x86_shared_cache_size_half
Introduced after 2.35 in:
commit 26b2478322
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Thu Apr 14 11:47:40 2022 -0500
x86: Reduce code size of mem{move|pcpy|cpy}-ssse3
1. Remove sse2 instructions when using the avx512 or avx version.
2. Fixup some format nits in how the address offsets where aligned.
3. Use more space efficient instructions in the conditional AVX
restoral.
- vpcmpeqq -> vpcmpeqb
- cmp imm32, r; jz -> inc r; jz
4. Use `rep movsb` instead of `rep movsq`. The former is guranteed to
be fast with the ERMS flags, the latter is not. The latter also
wastes an instruction in size setup.
The primary memmove_{impl}_unaligned_erms implementations don't
interact with this function. Putting them in same file both
wastes space and unnecessarily bloats a hot code section.
Implementation wise:
1. Remove the VZEROUPPER as memset_{impl}_unaligned_erms does not
use the L(stosb) label that was previously defined.
2. Don't give the hotpath (fallthrough) to zero size.
Code positioning wise:
Move memset_{chk}_erms to its own file. Leaving it in between the
memset_{impl}_unaligned both adds unnecessary complexity to the
file and wastes space in a relatively hot cache section.
These files simply include the sysdeps/posix implementations which would
be used even in the absence of the files. They have been unnecessary
since 7b17aeda0c when nice and signal were removed from the
syscalls.list file.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This maintains compatibility between <sys/mman.h> and <linux/uio.h>.
Before that, the addition of process_madvise made those two header
files incompatible. This has been observed resulting in a build
failure in LLDB's Process/Linux/NativeRegisterContextLinux_s390x.cpp
source file.
Fixes commit d19ee3473d
("linux: Add process_madvise").
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
When glibc is built with x86-64 ISA level v3, SSE run-time resolvers
aren't used. For x86-64 ISA level v4 build, both SSE and AVX resolvers
are unused. Check the minimum x86-64 ISA level to exclude the unused
run-time resolvers.
Add third argument to X86_ISA_CPU_FEATURES_ARCH_P macro so the runtime
CPU_FEATURES_ARCH_P check can be inverted if the
MINIMUM_X86_ISA_LEVEL is not high enough to constantly evaluate
the check.
Use this new macro to correct the backwards check in ifunc-evex.h
The function was tuned around 64-byte entry alignment and performs
better for all sizes with it.
As well different code boths where explicitly written to touch the
minimum number of cache line i.e sizes <= 32 touch only the entry
cache line.
By adding an internal alias to avoid the GOT indirection.
On some architecture, __libc_single_thread may be accessed through
copy relocations and thus it requires to update also the copies
default copy.
This is done by adding a new internal macro,
libc_hidden_data_{proto,def}, which has an addition argument that
specifies the alias name (instead of default __GI_ one).
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Fangrui Song <maskray@google.com>
It was added on Linux 5.2 (2db154b3ea8e14b04fee23e3fdfd5e9d17fbc6ae)
as way t move a mount from one place to another and, in the next
commit, allow to attach an unattached mount tree.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
It was added on 5.2 (93766fbd2696c2c4453dd8e1070977e9cd4e6b6d) to
provide a way by which a filesystem opened with fsopen and configured
by a series of fsconfig calls can have a detached mount object
created for it.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It was added on Linux 5.2 (24dcb3d90a1f67fe08c68a004af37df059d74005)
to start the process of preparing to create a superblock that will
then be mountable, using an fd as a context handle.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
