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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
// This file determines x86/AMD64 features a processor supports.
//
// We return:
// - 0 if the machine matches the asked-for feature.
// - 1 if the machine does not.
// - 2 if the asked-for feature isn't recognised (this will be the case for
// any feature if run on a non-x86/AMD64 machine).
// - 3 if there was a usage error (it also prints an error message).
// viz:
#define FEATURE_PRESENT 0
#define FEATURE_NOT_PRESENT 1
#define UNRECOGNISED_FEATURE 2
#define USAGE_ERROR 3
#define False 0
#define True 1
typedef int Bool;
#if defined(VGA_x86) || defined(VGA_amd64)
static void cpuid ( unsigned int n,
unsigned int* a, unsigned int* b,
unsigned int* c, unsigned int* d )
{
__asm__ __volatile__ (
"cpuid"
: "=a" (*a), "=b" (*b), "=c" (*c), "=d" (*d) /* output */
: "0" (n) /* input */
);
}
static Bool vendorStringEquals ( char* str )
{
char vstr[13];
unsigned int a, b, c, d;
cpuid(0, &a, &b, &c, &d);
memcpy(&vstr[0], &b, 4);
memcpy(&vstr[4], &d, 4);
memcpy(&vstr[8], &c, 4);
vstr[12] = 0;
return 0 == strcmp(vstr, str);
}
static Bool have_xgetbv ( void )
{
#if defined(VGA_amd64)
unsigned long long int w;
__asm__ __volatile__("movq $0,%%rcx ; "
".byte 0x0F,0x01,0xD0 ; " /* xgetbv */
"movq %%rax,%0"
:/*OUT*/"=r"(w) :/*IN*/
:/*TRASH*/"rdx","rcx");
if ((w & 6) == 6) {
/* OS has enabled both XMM and YMM state support */
return True;
} else {
return False;
}
#else
return False;
#endif
}
static Bool go(char* cpu)
{
unsigned int level = 0, cmask = 0, dmask = 0, a, b, c, d;
Bool require_amd = False;
Bool require_xgetbv = False;
if ( strcmp( cpu, "x86-fpu" ) == 0 ) {
level = 1;
dmask = 1 << 0;
} else if ( strcmp( cpu, "x86-cmov" ) == 0 ) {
level = 1;
dmask = 1 << 15;
} else if ( strcmp( cpu, "x86-mmx" ) == 0 ) {
level = 1;
dmask = 1 << 23;
} else if ( strcmp( cpu, "x86-mmxext" ) == 0 ) {
level = 0x80000001;
dmask = 1 << 22;
} else if ( strcmp( cpu, "x86-sse" ) == 0 ) {
level = 1;
dmask = 1 << 25;
} else if ( strcmp( cpu, "x86-sse2" ) == 0 ) {
level = 1;
dmask = 1 << 26;
} else if ( strcmp( cpu, "x86-sse3" ) == 0 ) {
level = 1;
cmask = 1 << 0;
} else if ( strcmp( cpu, "x86-ssse3" ) == 0 ) {
level = 1;
cmask = 1 << 9;
} else if ( strcmp( cpu, "x86-lzcnt" ) == 0 ) {
level = 0x80000001;
cmask = 1 << 5;
require_amd = True;
#if defined(VGA_amd64)
} else if ( strcmp( cpu, "amd64-sse3" ) == 0 ) {
level = 1;
cmask = 1 << 0;
} else if ( strcmp( cpu, "amd64-pclmulqdq" ) == 0 ) {
level = 1;
cmask = 1 << 1;
} else if ( strcmp( cpu, "amd64-ssse3" ) == 0 ) {
level = 1;
cmask = 1 << 9;
} else if ( strcmp( cpu, "amd64-cx16" ) == 0 ) {
level = 1;
cmask = 1 << 13;
} else if ( strcmp( cpu, "amd64-lzcnt" ) == 0 ) {
level = 0x80000001;
cmask = 1 << 5;
require_amd = True;
} else if ( strcmp( cpu, "amd64-sse42" ) == 0 ) {
level = 1;
cmask = 1 << 20;
} else if ( strcmp( cpu, "amd64-avx" ) == 0 ) {
level = 1;
cmask = (1 << 27) | (1 << 28);
require_xgetbv = True;
#endif
} else {
return UNRECOGNISED_FEATURE;
}
assert( !(cmask != 0 && dmask != 0) );
assert( !(cmask == 0 && dmask == 0) );
if (require_amd && !vendorStringEquals("AuthenticAMD"))
return FEATURE_NOT_PRESENT;
// regardless of what that feature actually is
cpuid( level & 0x80000000, &a, &b, &c, &d );
if ( a >= level ) {
cpuid( level, &a, &b, &c, &d );
if (dmask > 0 && (d & dmask) == dmask) {
if (require_xgetbv && !have_xgetbv())
return FEATURE_NOT_PRESENT;
else
return FEATURE_PRESENT;
}
if (cmask > 0 && (c & cmask) == cmask) {
if (require_xgetbv && !have_xgetbv())
return FEATURE_NOT_PRESENT;
else
return FEATURE_PRESENT;
}
}
return FEATURE_NOT_PRESENT;
}
#else
static Bool go(char* cpu)
{
// Feature not recognised (non-x86/AMD64 machine!)
return UNRECOGNISED_FEATURE;
}
#endif // defined(VGA_x86) || defined(VGA_amd64)
//---------------------------------------------------------------------------
// main
//---------------------------------------------------------------------------
int main(int argc, char **argv)
{
if ( argc != 2 ) {
fprintf( stderr, "usage: x86_amd64_features <feature>\n" );
exit(USAGE_ERROR);
}
return go(argv[1]);
}
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