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107e6a3c22
Support usable check for all CPU features with the following changes:
1. Change struct cpu_features to
struct cpuid_features
{
struct cpuid_registers cpuid;
struct cpuid_registers usable;
};
struct cpu_features
{
struct cpu_features_basic basic;
struct cpuid_features features[COMMON_CPUID_INDEX_MAX];
unsigned int preferred[PREFERRED_FEATURE_INDEX_MAX];
...
};
so that there is a usable bit for each cpuid bit.
2. After the cpuid bits have been initialized, copy the known bits to the
usable bits. EAX/EBX from INDEX_1 and EAX from INDEX_7 aren't used for
CPU feature detection.
3. Clear the usable bits which require OS support.
4. If the feature is supported by OS, copy its cpuid bit to its usable
bit.
5. Replace HAS_CPU_FEATURE and CPU_FEATURES_CPU_P with CPU_FEATURE_USABLE
and CPU_FEATURE_USABLE_P to check if a feature is usable.
6. Add DEPR_FPU_CS_DS for INDEX_7_EBX_13.
7. Unset MPX feature since it has been deprecated.
The results are
1. If the feature is known and doesn't requre OS support, its usable bit
is copied from the cpuid bit.
2. Otherwise, its usable bit is copied from the cpuid bit only if the
feature is known to supported by OS.
3. CPU_FEATURE_USABLE/CPU_FEATURE_USABLE_P are used to check if the
feature can be used.
4. HAS_CPU_FEATURE/CPU_FEATURE_CPU_P are used to check if CPU supports
the feature.
55 lines
1.7 KiB
C
55 lines
1.7 KiB
C
/* Set the FPU control word for x86.
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Copyright (C) 2003-2020 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 <math.h>
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#include <fpu_control.h>
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#include <fenv.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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#include <dl-procinfo.h>
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void
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__setfpucw (fpu_control_t set)
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{
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fpu_control_t cw;
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/* Fetch the current control word. */
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__asm__ ("fnstcw %0" : "=m" (*&cw));
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/* Preserve the reserved bits, and set the rest as the user
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specified (or the default, if the user gave zero). */
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cw &= _FPU_RESERVED;
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cw |= set & ~_FPU_RESERVED;
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__asm__ ("fldcw %0" : : "m" (*&cw));
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/* If the CPU supports SSE, we set the MXCSR as well. */
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if (CPU_FEATURE_USABLE (SSE))
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{
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unsigned int xnew_exc;
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/* Get the current MXCSR. */
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__asm__ ("stmxcsr %0" : "=m" (*&xnew_exc));
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xnew_exc &= ~((0xc00 << 3) | (FE_ALL_EXCEPT << 7));
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xnew_exc |= ((set & 0xc00) << 3) | ((set & FE_ALL_EXCEPT) << 7);
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__asm__ ("ldmxcsr %0" : : "m" (*&xnew_exc));
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}
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}
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