cpu_feature.c

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  Copyright (c) 2018, Intel Corporation

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        may be used to endorse or promote products derived from this software
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  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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#include <stdint.h>
#ifdef __WIN32
#include <intrin.h>
#endif

#include "cpu_feature.h"

struct cpuid_regs {
        uint32_t eax;
        uint32_t ebx;
        uint32_t ecx;
        uint32_t edx;
};

static struct cpuid_regs cpuid_1_0;
static struct cpuid_regs cpuid_7_0;

/*
 * A C wrapper for CPUID opcode
 *
 * Parameters:
 *    [in] leaf    - CPUID leaf number (EAX)
 *    [in] subleaf - CPUID sub-leaf number (ECX)
 *    [out] out    - registers structure to store results of CPUID into
 */
static void
__mbcpuid(const unsigned leaf, const unsigned subleaf, struct cpuid_regs *out)
{
#ifdef _WIN32
        /* Windows */
        int regs[4];

        __cpuidex(regs, leaf, subleaf);
        out->eax = regs[0];
        out->ebx = regs[1];
        out->ecx = regs[2];
        out->edx = regs[3];
#else
        /* Linux */
        asm volatile("mov %4, %%eax\n\t"
                     "mov %5, %%ecx\n\t"
                     "cpuid\n\t"
                     "mov %%eax, %0\n\t"
                     "mov %%ebx, %1\n\t"
                     "mov %%ecx, %2\n\t"
                     "mov %%edx, %3\n\t"
                     : "=g" (out->eax), "=g" (out->ebx), "=g" (out->ecx),
                       "=g" (out->edx)
                     : "g" (leaf), "g" (subleaf)
                     : "%eax", "%ebx", "%ecx", "%edx");
#endif /* Linux */
}

static uint32_t detect_shani(void)
{
        /* Check presence of SHANI - bit 29 of EBX */
        return (cpuid_7_0.ebx & (1 << 29));
}

static uint32_t detect_aesni(void)
{
        /* Check presence of AESNI - bit 25 of ECX */
        return (cpuid_1_0.ecx & (1 << 25));
}

static uint32_t detect_pclmulqdq(void)
{
        /* Check presence of PCLMULQDQ - bit 1 of ECX */
        return (cpuid_1_0.ecx & (1 << 1));
}

static uint32_t detect_cmov(void)
{
        /* Check presence of CMOV - bit 15 of EDX */
        return (cpuid_1_0.edx & (1 << 15));
}

static uint32_t detect_sse42(void)
{
        /* Check presence of SSE4.2 - bit 20 of ECX */
        return (cpuid_1_0.ecx & (1 << 20));
}

static uint32_t detect_avx(void)
{
        /* Check presence of AVX - bit 28 of ECX */
        return (cpuid_1_0.ecx & (1 << 28));
}

static uint32_t detect_avx2(void)
{
        /* Check presence of AVX2 - bit 5 of EBX */
        return (cpuid_7_0.ebx & (1 << 5));
}

static uint32_t detect_avx512f(void)
{
        /* Check presence of AVX512F - bit 16 of EBX */
        return (cpuid_7_0.ebx & (1 << 16));
}

static uint32_t detect_avx512dq(void)
{
        /* Check presence of AVX512DQ - bit 17 of EBX */
        return (cpuid_7_0.ebx & (1 << 17));
}

static uint32_t detect_avx512cd(void)
{
        /* Check presence of AVX512CD - bit 28 of EBX */
        return (cpuid_7_0.ebx & (1 << 28));
}

static uint32_t detect_avx512bw(void)
{
        /* Check presence of AVX512BW - bit 30 of EBX */
        return (cpuid_7_0.ebx & (1 << 30));
}

static uint32_t detect_avx512vl(void)
{
        /* Check presence of AVX512VL - bit 31 of EBX */
        return (cpuid_7_0.ebx & (1 << 31));
}

static uint32_t detect_vaes(void)
{
        /* Check presence of VAES - bit 9 of ECX */
        return (cpuid_7_0.ecx & (1 << 9));
}

static uint32_t detect_vpclmulqdq(void)
{
        /* Check presence of VAES - bit 10 of ECX */
        return (cpuid_7_0.ecx & (1 << 10));
}

uint64_t cpu_feature_detect(void)
{
        static const struct {
                unsigned req_leaf_number;
                uint64_t feat;
                uint32_t (*detect_fn)(void);
        } feat_tab[] = {
                { 7, IMB_FEATURE_SHANI, detect_shani },
                { 1, IMB_FEATURE_AESNI, detect_aesni },
                { 1, IMB_FEATURE_PCLMULQDQ, detect_pclmulqdq },
                { 1, IMB_FEATURE_CMOV, detect_cmov },
                { 1, IMB_FEATURE_SSE4_2, detect_sse42 },
                { 1, IMB_FEATURE_AVX, detect_avx },
                { 7, IMB_FEATURE_AVX2, detect_avx2 },
                { 7, IMB_FEATURE_AVX512F, detect_avx512f },
                { 7, IMB_FEATURE_AVX512DQ, detect_avx512dq },
                { 7, IMB_FEATURE_AVX512CD, detect_avx512cd },
                { 7, IMB_FEATURE_AVX512BW, detect_avx512bw },
                { 7, IMB_FEATURE_AVX512VL, detect_avx512vl },
                { 7, IMB_FEATURE_VAES, detect_vaes },
                { 7, IMB_FEATURE_VPCLMULQDQ, detect_vpclmulqdq },
        };
        struct cpuid_regs r;
        unsigned hi_leaf_number = 0;
        uint64_t features = 0;
        unsigned i;

        /* Get highest supported CPUID leaf number */
        __mbcpuid(0x0, 0x0, &r);
        hi_leaf_number = r.eax;

        /* Get the most common CPUID leafs to speed up the detection */
        if (hi_leaf_number >= 1)
                __mbcpuid(0x1, 0x0, &cpuid_1_0);

        if (hi_leaf_number >= 7)
                __mbcpuid(0x7, 0x0, &cpuid_7_0);

        for (i = 0; i < IMB_DIM(feat_tab); i++) {
                if (hi_leaf_number < feat_tab[i].req_leaf_number)
                        continue;

                if (feat_tab[i].detect_fn() != 0)
                        features |= feat_tab[i].feat;
        }

#ifdef SAFE_DATA
        features |= IMB_FEATURE_SAFE_DATA;
#endif
#ifdef SAFE_PARAM
        features |= IMB_FEATURE_SAFE_PARAM;
#endif

        return features;
}

uint64_t cpu_feature_adjust(const uint64_t flags, uint64_t features)
{
        if (flags & IMB_FLAG_SHANI_OFF)
                features &= ~IMB_FEATURE_SHANI;

        if (flags & IMB_FLAG_AESNI_OFF)
                features &= ~IMB_FEATURE_AESNI;

        return features;
}