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 matches the asked-for feature.
  11 // - 1 if the machine does not.
  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,
  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)         /* 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, &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, cmask = 0, dmask = 0, a, b, c, d;
  74    Bool require_amd = False;
  75    Bool require_xgetbv = False;
  76    if        ( strcmp( cpu, "x86-fpu" ) == 0 ) {
  77      level = 1;
  78      dmask = 1 << 0;
  79    } else if ( strcmp( cpu, "x86-cmov" ) == 0 ) {
  80      level = 1;
  81      dmask = 1 << 15;
  82    } else if ( strcmp( cpu, "x86-mmx" ) == 0 ) {
  83      level = 1;
  84      dmask = 1 << 23;
  85    } else if ( strcmp( cpu, "x86-mmxext" ) == 0 ) {
  86      level = 0x80000001;
  87      dmask = 1 << 22;
  88    } else if ( strcmp( cpu, "x86-sse" ) == 0 ) {
  89      level = 1;
  90      dmask = 1 << 25;
  91    } else if ( strcmp( cpu, "x86-sse2" ) == 0 ) {
  92      level = 1;
  93      dmask = 1 << 26;
  94    } else if ( strcmp( cpu, "x86-sse3" ) == 0 ) {
  95      level = 1;
  96      cmask = 1 << 0;
  97    } else if ( strcmp( cpu, "x86-ssse3" ) == 0 ) {
  98      level = 1;
  99      cmask = 1 << 9;
 100    } else if ( strcmp( cpu, "x86-lzcnt" ) == 0 ) {
 101      level = 0x80000001;
 102      cmask = 1 << 5;
 103      require_amd = True;
 104 #if defined(VGA_amd64)
 105    } else if ( strcmp( cpu, "amd64-sse3" ) == 0 ) {
 106      level = 1;
 107      cmask = 1 << 0;
 108    } else if ( strcmp( cpu, "amd64-pclmulqdq" ) == 0 ) {
 109      level = 1;
 110      cmask = 1 << 1;
 111    } else if ( strcmp( cpu, "amd64-ssse3" ) == 0 ) {
 112      level = 1;
 113      cmask = 1 << 9;
 114    } else if ( strcmp( cpu, "amd64-cx16" ) == 0 ) {
 115      level = 1;
 116      cmask = 1 << 13;
 117    } else if ( strcmp( cpu, "amd64-lzcnt" ) == 0 ) {
 118      level = 0x80000001;
 119      cmask = 1 << 5;
 120      require_amd = True;
 121    } else if ( strcmp( cpu, "amd64-sse42" ) == 0 ) {
 122      level = 1;
 123      cmask = 1 << 20;
 124    } else if ( strcmp( cpu, "amd64-avx" ) == 0 ) {
 125      level = 1;
 126      cmask = (1 << 27) | (1 << 28);
 127      require_xgetbv = True;
 128    } else if (strcmp (cpu,  "amd64-fma4" ) == 0) {
 129      level = 0x80000001;
 130      cmask = 1 << 16;
 131      require_amd = True;
 132 #endif
 133    } else {
 134      return UNRECOGNISED_FEATURE;
 135    }
 136
 137    assert( !(cmask != 0 && dmask != 0) );
 138    assert( !(cmask == 0 && dmask == 0) );
 139
 140    if (require_amd && !vendorStringEquals("AuthenticAMD"))
 141       return FEATURE_NOT_PRESENT;
 142       // regardless of what that feature actually is
 143
 144    cpuid( level & 0x80000000, &a, &b, &c, &d );
 145
 146    if ( a >= level ) {
 147       cpuid( level, &a, &b, &c, &d );
 148
 149       if (dmask > 0 && (d & dmask) == dmask) {
 150          if (require_xgetbv && !have_xgetbv())
 151             return FEATURE_NOT_PRESENT;
 152          else
 153             return FEATURE_PRESENT;
 154       }
 155       if (cmask > 0 && (c & cmask) == cmask) {
 156          if (require_xgetbv && !have_xgetbv())
 157             return FEATURE_NOT_PRESENT;
 158          else
 159             return FEATURE_PRESENT;
 160       }
 161    }
 162    return FEATURE_NOT_PRESENT;
 163 }
 164
 165 #else
 166
 167 static Bool go(char* cpu)
 168 {
 169    // Feature not recognised (non-x86/AMD64 machine!)
 170    return UNRECOGNISED_FEATURE;
 171 }
 172
 173 #endif   // defined(VGA_x86)  || defined(VGA_amd64)
 174
 175
 176 //---------------------------------------------------------------------------
 177 // main
 178 //---------------------------------------------------------------------------
 179 int main(int argc, char **argv)
 180 {
 181    if ( argc != 2 ) {
 182       fprintf( stderr, "usage: x86_amd64_features <feature>\n" );
 183       exit(USAGE_ERROR);
 184    }
 185    return go(argv[1]);
 186 }