cpuid.c

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#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

#include "helpers/helpers.h"

static const char *cpu_vendor_table[X86_VENDOR_MAX] = {
    "Unknown", "GenuineIntel", "AuthenticAMD",
};

#if defined(__i386__) || defined(__x86_64__)

/* from gcc */
#include <cpuid.h>

/*
 * CPUID functions returning a single datum
 *
 * Define unsigned int cpuid_e[abcd]x(unsigned int op)
 */
#define cpuid_func(reg)                 \
    unsigned int cpuid_##reg(unsigned int op)   \
    {                       \
    unsigned int eax, ebx, ecx, edx;        \
    __cpuid(op, eax, ebx, ecx, edx);        \
    return reg;                 \
    }
cpuid_func(eax);
cpuid_func(ebx);
cpuid_func(ecx);
cpuid_func(edx);

#endif /* defined(__i386__) || defined(__x86_64__) */

/* get_cpu_info
 *
 * Extract CPU vendor, family, model, stepping info from /proc/cpuinfo
 *
 * Returns 0 on success or a negativ error code
 *
 * TBD: Should there be a cpuid alternative for this if /proc is not mounted?
 */
int get_cpu_info(unsigned int cpu, struct cpupower_cpu_info *cpu_info)
{
    FILE *fp;
    char value[64];
    unsigned int proc, x;
    unsigned int unknown = 0xffffff;
    unsigned int cpuid_level, ext_cpuid_level;

    int ret = -EINVAL;

    cpu_info->vendor        = X86_VENDOR_UNKNOWN;
    cpu_info->family        = unknown;
    cpu_info->model         = unknown;
    cpu_info->stepping      = unknown;
    cpu_info->caps          = 0;

    fp = fopen("/proc/cpuinfo", "r");
    if (!fp)
        return -EIO;

    while (!feof(fp)) {
        if (!fgets(value, 64, fp))
            continue;
        value[63 - 1] = '\0';

        if (!strncmp(value, "processor\t: ", 12))
            sscanf(value, "processor\t: %u", &proc);

        if (proc != cpu)
            continue;

        /* Get CPU vendor */
        if (!strncmp(value, "vendor_id", 9)) {
            for (x = 1; x < X86_VENDOR_MAX; x++) {
                if (strstr(value, cpu_vendor_table[x]))
                    cpu_info->vendor = x;
            }
        /* Get CPU family, etc. */
        } else if (!strncmp(value, "cpu family\t: ", 13)) {
            sscanf(value, "cpu family\t: %u",
                   &cpu_info->family);
        } else if (!strncmp(value, "model\t\t: ", 9)) {
            sscanf(value, "model\t\t: %u",
                   &cpu_info->model);
        } else if (!strncmp(value, "stepping\t: ", 10)) {
            sscanf(value, "stepping\t: %u",
                   &cpu_info->stepping);

            /* Exit -> all values must have been set */
            if (cpu_info->vendor == X86_VENDOR_UNKNOWN ||
                cpu_info->family == unknown ||
                cpu_info->model == unknown ||
                cpu_info->stepping == unknown) {
                ret = -EINVAL;
                goto out;
            }

            ret = 0;
            goto out;
        }
    }
    ret = -ENODEV;
out:
    fclose(fp);
    /* Get some useful CPU capabilities from cpuid */
    if (cpu_info->vendor != X86_VENDOR_AMD &&
        cpu_info->vendor != X86_VENDOR_INTEL)
        return ret;

    cpuid_level = cpuid_eax(0);
    ext_cpuid_level = cpuid_eax(0x80000000);

    /* Invariant TSC */
    if (ext_cpuid_level >= 0x80000007 &&
        (cpuid_edx(0x80000007) & (1 << 8)))
        cpu_info->caps |= CPUPOWER_CAP_INV_TSC;

    /* Aperf/Mperf registers support */
    if (cpuid_level >= 6 && (cpuid_ecx(6) & 0x1))
        cpu_info->caps |= CPUPOWER_CAP_APERF;

    /* AMD Boost state enable/disable register */
    if (cpu_info->vendor == X86_VENDOR_AMD) {
        if (ext_cpuid_level >= 0x80000007 &&
            (cpuid_edx(0x80000007) & (1 << 9)))
            cpu_info->caps |= CPUPOWER_CAP_AMD_CBP;
    }

    if (cpu_info->vendor == X86_VENDOR_INTEL) {
        if (cpuid_level >= 6 &&
            (cpuid_eax(6) & (1 << 1)))
            cpu_info->caps |= CPUPOWER_CAP_INTEL_IDA;
    }

    if (cpu_info->vendor == X86_VENDOR_INTEL) {
        /* Intel's perf-bias MSR support */
        if (cpuid_level >= 6 && (cpuid_ecx(6) & (1 << 3)))
            cpu_info->caps |= CPUPOWER_CAP_PERF_BIAS;

        /* Intel's Turbo Ratio Limit support */
        if (cpu_info->family == 6) {
            switch (cpu_info->model) {
            case 0x1A:  /* Core i7, Xeon 5500 series
                     * Bloomfield, Gainstown NHM-EP
                     */
            case 0x1E:  /* Core i7 and i5 Processor
                     * Clarksfield, Lynnfield, Jasper Forest
                     */
            case 0x1F:  /* Core i7 and i5 Processor - Nehalem */
            case 0x25:  /* Westmere Client
                     * Clarkdale, Arrandale
                     */
            case 0x2C:  /* Westmere EP - Gulftown */
                cpu_info->caps |= CPUPOWER_CAP_HAS_TURBO_RATIO;
            case 0x2A:  /* SNB */
            case 0x2D:  /* SNB Xeon */
                cpu_info->caps |= CPUPOWER_CAP_HAS_TURBO_RATIO;
                cpu_info->caps |= CPUPOWER_CAP_IS_SNB;
                break;
            case 0x2E:  /* Nehalem-EX Xeon - Beckton */
            case 0x2F:  /* Westmere-EX Xeon - Eagleton */
            default:
                break;
            }
        }
    }

    /*  printf("ID: %u - Extid: 0x%x - Caps: 0x%llx\n",
        cpuid_level, ext_cpuid_level, cpu_info->caps);
    */
    return ret;
}