tests/x86_amd64_features.c

   1
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <assert.h>
   6
   7 // This file determines x86/AMD64 features a processor supports.
   8 //
   9 // We return:
  10 // - 0 if the machine has the asked-for feature.
  11 // - 1 if the machine doesn't have the asked-for feature.
  12 // - 2 if the asked-for feature isn't recognised (this will be the case for
  13 //     any feature if run on a non-x86/AMD64 machine).
  14 // - 3 if there was a usage error (it also prints an error message).
  15 // viz:
  16 #define FEATURE_PRESENT       0
  17 #define FEATURE_NOT_PRESENT   1
  18 #define UNRECOGNISED_FEATURE  2
  19 #define USAGE_ERROR           3
  20
  21
  22 #define False  0
  23 #define True   1
  24 typedef int    Bool;
  25
  26
  27 #if defined(VGA_x86) || defined(VGA_amd64)
  28 static void cpuid ( unsigned int n, unsigned int m,
  29                     unsigned int* a, unsigned int* b,
  30                     unsigned int* c, unsigned int* d )
  31 {
  32    __asm__ __volatile__ (
  33       "cpuid"
  34       : "=a" (*a), "=b" (*b), "=c" (*c), "=d" (*d)      /* output */
  35       : "0" (n), "2" (m)         /* input */
  36    );
  37 }
  38
  39 static Bool vendorStringEquals ( char* str )
  40 {
  41    char vstr[13];
  42    unsigned int a, b, c, d;
  43    cpuid(0, 0, &a, &b, &c, &d);
  44    memcpy(&vstr[0], &b, 4);
  45    memcpy(&vstr[4], &d, 4);
  46    memcpy(&vstr[8], &c, 4);
  47    vstr[12] = 0;
  48    return 0 == strcmp(vstr, str);
  49 }
  50
  51 static Bool have_xgetbv ( void )
  52 {
  53 #if defined(VGA_amd64)
  54    unsigned long long int w;
  55    __asm__ __volatile__("movq $0,%%rcx ; "
  56                         ".byte 0x0F,0x01,0xD0 ; " /* xgetbv */
  57                         "movq %%rax,%0"
  58                         :/*OUT*/"=r"(w) :/*IN*/
  59                         :/*TRASH*/"rdx","rcx");
  60    if ((w & 6) == 6) {
  61       /* OS has enabled both XMM and YMM state support */
  62       return True;
  63    } else {
  64       return False;
  65    }
  66 #else
  67    return False;
  68 #endif
  69 }
  70
  71 static Bool go(char* cpu)
  72 {
  73    unsigned int level = 0, sublevel = 0;
  74    unsigned int amask = 0, bmask = 0, cmask = 0, dmask = 0;
  75    unsigned int a, b, c, d;
  76    Bool require_amd = False;
  77    Bool require_xgetbv = False;
  78    if        ( strcmp( cpu, "x86-fpu" ) == 0 ) {
  79      level = 1;
  80      dmask = 1 << 0;
  81    } else if ( strcmp( cpu, "x86-cmov" ) == 0 ) {
  82      level = 1;
  83      dmask = 1 << 15;
  84    } else if ( strcmp( cpu, "x86-mmx" ) == 0 ) {
  85      level = 1;
  86      dmask = 1 << 23;
  87    } else if ( strcmp( cpu, "x86-mmxext" ) == 0 ) {
  88      level = 0x80000001;
  89      dmask = 1 << 22;
  90    } else if ( strcmp( cpu, "x86-sse" ) == 0 ) {
  91      level = 1;
  92      dmask = 1 << 25;
  93    } else if ( strcmp( cpu, "x86-sse2" ) == 0 ) {
  94      level = 1;
  95      dmask = 1 << 26;
  96    } else if ( strcmp( cpu, "x86-sse3" ) == 0 ) {
  97      level = 1;
  98      cmask = 1 << 0;
  99    } else if ( strcmp( cpu, "x86-ssse3" ) == 0 ) {
 100      level = 1;
 101      cmask = 1 << 9;
 102    } else if ( strcmp( cpu, "x86-lzcnt" ) == 0 ) {
 103      level = 0x80000001;
 104      cmask = 1 << 5;
 105      require_amd = True;
 106 #if defined(VGA_amd64)
 107    } else if ( strcmp( cpu, "amd64-sse3" ) == 0 ) {
 108      level = 1;
 109      cmask = 1 << 0;
 110    } else if ( strcmp( cpu, "amd64-pclmulqdq" ) == 0 ) {
 111      level = 1;
 112      cmask = 1 << 1;
 113    } else if ( strcmp( cpu, "amd64-ssse3" ) == 0 ) {
 114      level = 1;
 115      cmask = 1 << 9;
 116    } else if ( strcmp( cpu, "amd64-cx16" ) == 0 ) {
 117      level = 1;
 118      cmask = 1 << 13;
 119    } else if ( strcmp( cpu, "amd64-lzcnt" ) == 0 ) {
 120      level = 0x80000001;
 121      cmask = 1 << 5;
 122      require_amd = True;
 123    } else if ( strcmp( cpu, "amd64-sse42" ) == 0 ) {
 124      level = 1;
 125      cmask = 1 << 20;
 126    } else if ( strcmp( cpu, "amd64-avx" ) == 0 ) {
 127      level = 1;
 128      cmask = (1 << 27) | (1 << 28);
 129      require_xgetbv = True;
 130    } else if (strcmp (cpu,  "amd64-fma4" ) == 0) {
 131      level = 0x80000001;
 132      cmask = 1 << 16;
 133      require_amd = True;
 134    } else if (strcmp (cpu,  "amd64-f16c" ) == 0) {
 135       level = 1;
 136       cmask = 1 << 29;
 137    } else if (strcmp (cpu,  "amd64-rdrand" ) == 0) {
 138       level = 1;
 139       cmask = 1 << 30;
 140    } else if (strcmp (cpu,  "amd64-rdseed" ) == 0) {
 141       level = 7;
 142       bmask = 1 << 18;
 143 #endif
 144    } else {
 145      return UNRECOGNISED_FEATURE;
 146    }
 147
 148    assert( !(cmask != 0 && dmask != 0 && bmask != 0) );
 149    assert( !(cmask == 0 && dmask == 0 && bmask == 0) );
 150
 151    if (require_amd && !vendorStringEquals("AuthenticAMD"))
 152       return FEATURE_NOT_PRESENT;
 153       // regardless of what that feature actually is
 154
 155    cpuid( level & 0x80000000, 0, &a, &b, &c, &d );
 156
 157    if ( a >= level ) {
 158       cpuid( level, sublevel, &a, &b, &c, &d );
 159
 160       if (amask > 0 && (a & amask) == amask)
 161          return FEATURE_PRESENT;
 162
 163       if (bmask > 0 && (b & bmask) == bmask)
 164          return FEATURE_PRESENT;
 165
 166       if (dmask > 0 && (d & dmask) == dmask) {
 167          if (require_xgetbv && !have_xgetbv())
 168             return FEATURE_NOT_PRESENT;
 169          else
 170             return FEATURE_PRESENT;
 171       }
 172       if (cmask > 0 && (c & cmask) == cmask) {
 173          if (require_xgetbv && !have_xgetbv())
 174             return FEATURE_NOT_PRESENT;
 175          else
 176             return FEATURE_PRESENT;
 177       }
 178    }
 179    return FEATURE_NOT_PRESENT;
 180 }
 181
 182 #else
 183
 184 static Bool go(char* cpu)
 185 {
 186    // Feature not recognised (non-x86/AMD64 machine!)
 187    return UNRECOGNISED_FEATURE;
 188 }
 189
 190 #endif   // defined(VGA_x86)  || defined(VGA_amd64)
 191
 192
 193 //---------------------------------------------------------------------------
 194 // main
 195 //---------------------------------------------------------------------------
 196 int main(int argc, char **argv)
 197 {
 198    if ( argc != 2 ) {
 199       fprintf( stderr, "usage: x86_amd64_features <feature>\n" );
 200       exit(USAGE_ERROR);
 201    }
 202    return go(argv[1]);
 203 }