318 lines
9.6 KiB
C
318 lines
9.6 KiB
C
|
/* x86 CPU feature tuning.
|
||
|
|
This file is part of the GNU C Library.
|
||
|
|
Copyright (C) 2017-2022 Free Software Foundation, Inc.
|
||
|
|
|
||
|
|
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
|
||
|
|
<https://www.gnu.org/licenses/>. */
|
||
|
|
|
||
|
|
#if HAVE_TUNABLES
|
||
|
|
# define TUNABLE_NAMESPACE cpu
|
||
|
|
# include <stdbool.h>
|
||
|
|
# include <stdint.h>
|
||
|
|
# include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
|
||
|
|
# include <elf/dl-tunables.h>
|
||
|
|
# include <string.h>
|
||
|
|
# include <cpu-features.h>
|
||
|
|
# include <ldsodefs.h>
|
||
|
|
|
||
|
|
/* We can't use IFUNC memcmp nor strlen in init_cpu_features from libc.a
|
||
|
|
since IFUNC must be set up by init_cpu_features. */
|
||
|
|
# if defined USE_MULTIARCH && !defined SHARED
|
||
|
|
# ifdef __x86_64__
|
||
|
|
/* DEFAULT_MEMCMP by sysdeps/x86_64/memcmp-isa-default-impl.h. */
|
||
|
|
# include <sysdeps/x86_64/memcmp-isa-default-impl.h>
|
||
|
|
# else
|
||
|
|
# define DEFAULT_MEMCMP __memcmp_ia32
|
||
|
|
# endif
|
||
|
|
extern __typeof (memcmp) DEFAULT_MEMCMP;
|
||
|
|
# else
|
||
|
|
# define DEFAULT_MEMCMP memcmp
|
||
|
|
# endif
|
||
|
|
|
||
|
|
# define CHECK_GLIBC_IFUNC_CPU_OFF(f, cpu_features, name, len) \
|
||
|
|
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
|
||
|
|
if (!DEFAULT_MEMCMP (f, #name, len)) \
|
||
|
|
{ \
|
||
|
|
CPU_FEATURE_UNSET (cpu_features, name) \
|
||
|
|
break; \
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Disable a preferred feature NAME. We don't enable a preferred feature
|
||
|
|
which isn't available. */
|
||
|
|
# define CHECK_GLIBC_IFUNC_PREFERRED_OFF(f, cpu_features, name, len) \
|
||
|
|
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
|
||
|
|
if (!DEFAULT_MEMCMP (f, #name, len)) \
|
||
|
|
{ \
|
||
|
|
cpu_features->preferred[index_arch_##name] \
|
||
|
|
&= ~bit_arch_##name; \
|
||
|
|
break; \
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Enable/disable a preferred feature NAME. */
|
||
|
|
# define CHECK_GLIBC_IFUNC_PREFERRED_BOTH(f, cpu_features, name, \
|
||
|
|
disable, len) \
|
||
|
|
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
|
||
|
|
if (!DEFAULT_MEMCMP (f, #name, len)) \
|
||
|
|
{ \
|
||
|
|
if (disable) \
|
||
|
|
cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
|
||
|
|
else \
|
||
|
|
cpu_features->preferred[index_arch_##name] |= bit_arch_##name; \
|
||
|
|
break; \
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Enable/disable a preferred feature NAME. Enable a preferred feature
|
||
|
|
only if the feature NEED is usable. */
|
||
|
|
# define CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH(f, cpu_features, name, \
|
||
|
|
need, disable, len) \
|
||
|
|
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
|
||
|
|
if (!DEFAULT_MEMCMP (f, #name, len)) \
|
||
|
|
{ \
|
||
|
|
if (disable) \
|
||
|
|
cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
|
||
|
|
else if (CPU_FEATURE_USABLE_P (cpu_features, need)) \
|
||
|
|
cpu_features->preferred[index_arch_##name] |= bit_arch_##name; \
|
||
|
|
break; \
|
||
|
|
}
|
||
|
|
|
||
|
|
attribute_hidden
|
||
|
|
void
|
||
|
|
TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
|
||
|
|
{
|
||
|
|
/* The current IFUNC selection is based on microbenchmarks in glibc.
|
||
|
|
It should give the best performance for most workloads. But other
|
||
|
|
choices may have better performance for a particular workload or on
|
||
|
|
the hardware which wasn't available when the selection was made.
|
||
|
|
The environment variable:
|
||
|
|
|
||
|
|
GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,-zzz,....
|
||
|
|
|
||
|
|
can be used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature
|
||
|
|
yyy and zzz, where the feature name is case-sensitive and has to
|
||
|
|
match the ones in cpu-features.h. It can be used by glibc developers
|
||
|
|
to tune for a new processor or override the IFUNC selection to
|
||
|
|
improve performance for a particular workload.
|
||
|
|
|
||
|
|
NOTE: the IFUNC selection may change over time. Please check all
|
||
|
|
multiarch implementations when experimenting. */
|
||
|
|
|
||
|
|
const char *p = valp->strval;
|
||
|
|
struct cpu_features *cpu_features = &GLRO(dl_x86_cpu_features);
|
||
|
|
size_t len;
|
||
|
|
|
||
|
|
do
|
||
|
|
{
|
||
|
|
const char *c, *n;
|
||
|
|
bool disable;
|
||
|
|
size_t nl;
|
||
|
|
|
||
|
|
for (c = p; *c != ','; c++)
|
||
|
|
if (*c == '\0')
|
||
|
|
break;
|
||
|
|
|
||
|
|
len = c - p;
|
||
|
|
disable = *p == '-';
|
||
|
|
if (disable)
|
||
|
|
{
|
||
|
|
n = p + 1;
|
||
|
|
nl = len - 1;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
n = p;
|
||
|
|
nl = len;
|
||
|
|
}
|
||
|
|
switch (nl)
|
||
|
|
{
|
||
|
|
default:
|
||
|
|
break;
|
||
|
|
case 3:
|
||
|
|
if (disable)
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX, 3);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, CX8, 3);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, FMA, 3);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, HTT, 3);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, IBT, 3);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, RTM, 3);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 4:
|
||
|
|
if (disable)
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX2, 4);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, BMI1, 4);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, BMI2, 4);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, CMOV, 4);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, ERMS, 4);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, FMA4, 4);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE2, 4);
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_OFF (n, cpu_features, I586, 4);
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_OFF (n, cpu_features, I686, 4);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 5:
|
||
|
|
if (disable)
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, LZCNT, 5);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, MOVBE, 5);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SHSTK, 5);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSSE3, 5);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, XSAVE, 5);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 6:
|
||
|
|
if (disable)
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, POPCNT, 6);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_1, 6);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_2, 6);
|
||
|
|
if (!DEFAULT_MEMCMP (n, "XSAVEC", 6))
|
||
|
|
{
|
||
|
|
/* Update xsave_state_size to XSAVE state size. */
|
||
|
|
cpu_features->xsave_state_size
|
||
|
|
= cpu_features->xsave_state_full_size;
|
||
|
|
CPU_FEATURE_UNSET (cpu_features, XSAVEC);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 7:
|
||
|
|
if (disable)
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512F, 7);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, OSXSAVE, 7);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 8:
|
||
|
|
if (disable)
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512CD, 8);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512BW, 8);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512DQ, 8);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512ER, 8);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512PF, 8);
|
||
|
|
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, AVX512VL, 8);
|
||
|
|
}
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_BOTH (n, cpu_features, Slow_BSF,
|
||
|
|
disable, 8);
|
||
|
|
break;
|
||
|
|
case 11:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_BOTH (n, cpu_features,
|
||
|
|
Prefer_ERMS,
|
||
|
|
disable, 11);
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_BOTH (n, cpu_features,
|
||
|
|
Prefer_FSRM,
|
||
|
|
disable, 11);
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH (n, cpu_features,
|
||
|
|
Slow_SSE4_2,
|
||
|
|
SSE4_2,
|
||
|
|
disable, 11);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 15:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_BOTH (n, cpu_features,
|
||
|
|
Fast_Rep_String,
|
||
|
|
disable, 15);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 16:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH
|
||
|
|
(n, cpu_features, Prefer_No_AVX512, AVX512F,
|
||
|
|
disable, 16);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 18:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_BOTH (n, cpu_features,
|
||
|
|
Fast_Copy_Backward,
|
||
|
|
disable, 18);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 19:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_BOTH (n, cpu_features,
|
||
|
|
Fast_Unaligned_Load,
|
||
|
|
disable, 19);
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_BOTH (n, cpu_features,
|
||
|
|
Fast_Unaligned_Copy,
|
||
|
|
disable, 19);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 20:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH
|
||
|
|
(n, cpu_features, Prefer_No_VZEROUPPER, AVX, disable,
|
||
|
|
20);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 23:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH
|
||
|
|
(n, cpu_features, AVX_Fast_Unaligned_Load, AVX,
|
||
|
|
disable, 23);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 24:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH
|
||
|
|
(n, cpu_features, MathVec_Prefer_No_AVX512, AVX512F,
|
||
|
|
disable, 24);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case 26:
|
||
|
|
{
|
||
|
|
CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH
|
||
|
|
(n, cpu_features, Prefer_PMINUB_for_stringop, SSE2,
|
||
|
|
disable, 26);
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
p += len + 1;
|
||
|
|
}
|
||
|
|
while (*p != '\0');
|
||
|
|
}
|
||
|
|
|
||
|
|
# if CET_ENABLED
|
||
|
|
|
||
|
|
attribute_hidden
|
||
|
|
void
|
||
|
|
TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *valp)
|
||
|
|
{
|
||
|
|
if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
|
||
|
|
GL(dl_x86_feature_control).ibt = cet_always_on;
|
||
|
|
else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
|
||
|
|
GL(dl_x86_feature_control).ibt = cet_always_off;
|
||
|
|
else if (DEFAULT_MEMCMP (valp->strval, "permissive",
|
||
|
|
sizeof ("permissive")) == 0)
|
||
|
|
GL(dl_x86_feature_control).ibt = cet_permissive;
|
||
|
|
}
|
||
|
|
|
||
|
|
attribute_hidden
|
||
|
|
void
|
||
|
|
TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *valp)
|
||
|
|
{
|
||
|
|
if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
|
||
|
|
GL(dl_x86_feature_control).shstk = cet_always_on;
|
||
|
|
else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
|
||
|
|
GL(dl_x86_feature_control).shstk = cet_always_off;
|
||
|
|
else if (DEFAULT_MEMCMP (valp->strval, "permissive",
|
||
|
|
sizeof ("permissive")) == 0)
|
||
|
|
GL(dl_x86_feature_control).shstk = cet_permissive;
|
||
|
|
}
|
||
|
|
# endif
|
||
|
|
#endif
|