mirror of
https://github.com/PSI-Rockin/DobieStation.git
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140 lines
4 KiB
C
140 lines
4 KiB
C
/*
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* x86/cpu_features.c - feature detection for x86 processors
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*
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* Copyright 2016 Eric Biggers
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following
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* conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "cpu_features.h"
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#if X86_CPU_FEATURES_ENABLED
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volatile u32 _cpu_features = 0;
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/* With old GCC versions we have to manually save and restore the x86_32 PIC
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* register (ebx). See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47602 */
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#if defined(__i386__) && defined(__PIC__)
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# define EBX_CONSTRAINT "=r"
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#else
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# define EBX_CONSTRAINT "=b"
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#endif
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/* Execute the CPUID instruction. */
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static inline void
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cpuid(u32 leaf, u32 subleaf, u32 *a, u32 *b, u32 *c, u32 *d)
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{
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__asm__(".ifnc %%ebx, %1; mov %%ebx, %1; .endif\n"
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"cpuid \n"
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".ifnc %%ebx, %1; xchg %%ebx, %1; .endif\n"
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: "=a" (*a), EBX_CONSTRAINT (*b), "=c" (*c), "=d" (*d)
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: "a" (leaf), "c" (subleaf));
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}
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/* Read an extended control register. */
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static inline u64
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read_xcr(u32 index)
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{
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u32 edx, eax;
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/* Execute the "xgetbv" instruction. Old versions of binutils do not
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* recognize this instruction, so list the raw bytes instead. */
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__asm__ (".byte 0x0f, 0x01, 0xd0" : "=d" (edx), "=a" (eax) : "c" (index));
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return ((u64)edx << 32) | eax;
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}
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#undef BIT
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#define BIT(nr) (1UL << (nr))
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#define XCR0_BIT_SSE BIT(1)
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#define XCR0_BIT_AVX BIT(2)
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#define XCR0_BIT_OPMASK BIT(5)
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#define XCR0_BIT_ZMM_HI256 BIT(6)
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#define XCR0_BIT_HI16_ZMM BIT(7)
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#define IS_SET(reg, nr) ((reg) & BIT(nr))
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#define IS_ALL_SET(reg, mask) (((reg) & (mask)) == (mask))
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/* Initialize _cpu_features with bits for interesting processor features. */
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void setup_cpu_features(void)
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{
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u32 features = 0;
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u32 dummy1, dummy2, dummy3, dummy4;
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u32 max_function;
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u32 features_1, features_2, features_3, features_4;
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bool os_avx_support = false;
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bool os_avx512_support = false;
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/* Get maximum supported function */
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cpuid(0, 0, &max_function, &dummy2, &dummy3, &dummy4);
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if (max_function < 1)
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goto out;
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/* Standard feature flags */
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cpuid(1, 0, &dummy1, &dummy2, &features_2, &features_1);
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if (IS_SET(features_1, 26))
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features |= X86_CPU_FEATURE_SSE2;
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if (IS_SET(features_2, 1))
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features |= X86_CPU_FEATURE_PCLMULQDQ;
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if (IS_SET(features_2, 27)) { /* OSXSAVE set? */
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u64 xcr0 = read_xcr(0);
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os_avx_support = IS_ALL_SET(xcr0,
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XCR0_BIT_SSE |
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XCR0_BIT_AVX);
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os_avx512_support = IS_ALL_SET(xcr0,
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XCR0_BIT_SSE |
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XCR0_BIT_AVX |
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XCR0_BIT_OPMASK |
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XCR0_BIT_ZMM_HI256 |
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XCR0_BIT_HI16_ZMM);
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}
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if (os_avx_support && IS_SET(features_2, 28))
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features |= X86_CPU_FEATURE_AVX;
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if (max_function < 7)
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goto out;
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/* Extended feature flags */
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cpuid(7, 0, &dummy1, &features_3, &features_4, &dummy4);
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if (os_avx_support && IS_SET(features_3, 5))
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features |= X86_CPU_FEATURE_AVX2;
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if (IS_SET(features_3, 8))
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features |= X86_CPU_FEATURE_BMI2;
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if (os_avx512_support && IS_SET(features_3, 30))
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features |= X86_CPU_FEATURE_AVX512BW;
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out:
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_cpu_features = features | X86_CPU_FEATURES_KNOWN;
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}
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#endif /* X86_CPU_FEATURES_ENABLED */
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