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x86: Use dl-symbol-redir-ifunc.h on cpu-tunables
The dl-symbol-redir-ifunc.h redirects compiler-generated libcalls to arch-specific memory implementations to avoid ifunc calls where it is not yet possible. The memcmp-isa-default-impl.h aims to fix the same issue by calling the specific memset implementation directly. Using the memcmp symbol directly allows the compiler to inline the memset calls (especially because _dl_tunable_set_hwcaps uses constants values), generating better code. Checked on x86_64-linux-gnu. Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com> Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
This commit is contained in:
Adhemerval Zanella
parent
eb9291aaa6
commit
4862d546c0
@ -19,6 +19,11 @@
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#ifndef _DL_IFUNC_GENERIC_H
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#define _DL_IFUNC_GENERIC_H
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#ifndef SHARED
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asm ("memset = __memset_ia32");
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asm ("memcmp = __memcmp_ia32");
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#endif /* SHARED */
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#endif
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@ -24,24 +24,11 @@
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#include <string.h>
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#include <cpu-features.h>
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#include <ldsodefs.h>
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/* We can't use IFUNC memcmp nor strlen in init_cpu_features from libc.a
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since IFUNC must be set up by init_cpu_features. */
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#if defined USE_MULTIARCH && !defined SHARED
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# ifdef __x86_64__
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/* DEFAULT_MEMCMP by sysdeps/x86_64/memcmp-isa-default-impl.h. */
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# include <sysdeps/x86_64/memcmp-isa-default-impl.h>
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# else
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# define DEFAULT_MEMCMP __memcmp_ia32
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# endif
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extern __typeof (memcmp) DEFAULT_MEMCMP;
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#else
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# define DEFAULT_MEMCMP memcmp
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#endif
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#include <dl-symbol-redir-ifunc.h>
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#define CHECK_GLIBC_IFUNC_CPU_OFF(f, cpu_features, name, len) \
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_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
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if (!DEFAULT_MEMCMP (f, #name, len)) \
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if (memcmp (f, #name, len) == 0) \
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{ \
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CPU_FEATURE_UNSET (cpu_features, name) \
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break; \
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@ -51,7 +38,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
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which isn't available. */
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#define CHECK_GLIBC_IFUNC_PREFERRED_OFF(f, cpu_features, name, len) \
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_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
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if (!DEFAULT_MEMCMP (f, #name, len)) \
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if (memcmp (f, #name, len) == 0) \
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{ \
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cpu_features->preferred[index_arch_##name] \
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&= ~bit_arch_##name; \
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@ -62,7 +49,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
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#define CHECK_GLIBC_IFUNC_PREFERRED_BOTH(f, cpu_features, name, \
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disable, len) \
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_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
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if (!DEFAULT_MEMCMP (f, #name, len)) \
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if (memcmp (f, #name, len) == 0) \
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{ \
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if (disable) \
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cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
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@ -76,7 +63,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
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#define CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH(f, cpu_features, name, \
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need, disable, len) \
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_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
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if (!DEFAULT_MEMCMP (f, #name, len)) \
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if (memcmp (f, #name, len) == 0) \
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{ \
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if (disable) \
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cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
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@ -177,7 +164,7 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
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CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, POPCNT, 6);
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CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_1, 6);
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CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_2, 6);
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if (!DEFAULT_MEMCMP (n, "XSAVEC", 6))
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if (memcmp (n, "XSAVEC", 6) == 0)
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{
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/* Update xsave_state_size to XSAVE state size. */
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cpu_features->xsave_state_size
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@ -290,12 +277,11 @@ attribute_hidden
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void
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TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *valp)
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{
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if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
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if (memcmp (valp->strval, "on", sizeof ("on")) == 0)
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GL(dl_x86_feature_control).ibt = cet_always_on;
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else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
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else if (memcmp (valp->strval, "off", sizeof ("off")) == 0)
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GL(dl_x86_feature_control).ibt = cet_always_off;
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else if (DEFAULT_MEMCMP (valp->strval, "permissive",
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sizeof ("permissive")) == 0)
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else if (memcmp (valp->strval, "permissive", sizeof ("permissive")) == 0)
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GL(dl_x86_feature_control).ibt = cet_permissive;
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}
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@ -303,12 +289,11 @@ attribute_hidden
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void
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TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *valp)
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{
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if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
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if (memcmp (valp->strval, "on", sizeof ("on")) == 0)
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GL(dl_x86_feature_control).shstk = cet_always_on;
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else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
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else if (memcmp (valp->strval, "off", sizeof ("off")) == 0)
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GL(dl_x86_feature_control).shstk = cet_always_off;
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else if (DEFAULT_MEMCMP (valp->strval, "permissive",
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sizeof ("permissive")) == 0)
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else if (memcmp (valp->strval, "permissive", sizeof ("permissive")) == 0)
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GL(dl_x86_feature_control).shstk = cet_permissive;
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}
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#endif
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@ -1,28 +0,0 @@
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/* Set default memcmp impl based on ISA level.
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Copyright (C) 2022-2023 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <isa-level.h>
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#if MINIMUM_X86_ISA_LEVEL == 1 || MINIMUM_X86_ISA_LEVEL == 2
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# define DEFAULT_MEMCMP __memcmp_sse2
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#elif MINIMUM_X86_ISA_LEVEL == 3
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# define DEFAULT_MEMCMP __memcmp_avx2_movbe
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#elif MINIMUM_X86_ISA_LEVEL == 4
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# define DEFAULT_MEMCMP __memcmp_evex_movbe
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#else
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# error "Unknown default memcmp implementation"
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#endif
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@ -19,6 +19,8 @@
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#ifndef _DL_IFUNC_GENERIC_H
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#define _DL_IFUNC_GENERIC_H
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#ifndef SHARED
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#include <isa-level.h>
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#if MINIMUM_X86_ISA_LEVEL >= 4
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@ -31,4 +33,17 @@
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asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC);
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#if MINIMUM_X86_ISA_LEVEL >= 4
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# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_evex_movbe"
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#elif MINIMUM_X86_ISA_LEVEL == 3
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# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_avx2_movbe"
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#else
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# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_sse2"
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#endif
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asm ("memcmp = " HAVE_MEMCMP_IFUNC_GENERIC);
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#endif /* SHARED */
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#endif
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