cpu.h

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/*
 * (c) 2004-2009 Author(s)
 *     economic rights: Technische Universität Dresden (Germany)
 * This file is part of TUD:OS and distributed under the terms of the
 * GNU Lesser General Public License 2.1.
 * Please see the COPYING-LGPL-2.1 file for details.
 */
 
#ifndef __L4_UTIL_CPU_H
#define __L4_UTIL_CPU_H
 
#include <l4/sys/compiler.h>
 
EXTERN_C_BEGIN
 
L4_INLINE int          l4util_cpu_has_cpuid(void);
 
L4_INLINE unsigned int l4util_cpu_capabilities(void);
 
L4_INLINE unsigned int l4util_cpu_capabilities_nocheck(void);
 
L4_INLINE void
l4util_cpu_cpuid(unsigned long mode,
                 unsigned long *eax, unsigned long *ebx,
                 unsigned long *ecx, unsigned long *edx);
 
static inline void
l4util_cpu_pause(void)
{
  __asm__ __volatile__ ("rep; nop");
}
 
L4_INLINE int
l4util_cpu_has_cpuid(void)
{
  unsigned long eax;
 
  asm volatile("pushl %%ebx             \t\n"
               "pushfl      \t\n"
               "popl %%eax    \t\n" /* get eflags */
               "movl %%eax, %%ebx \t\n" /* save it */
               "xorl $0x200000, %%eax \t\n" /* toggle ID bit */
               "pushl %%eax   \t\n"
               "popfl     \t\n" /* set again */
               "pushfl      \t\n"
               "popl %%eax    \t\n" /* get it again */
               "xorl %%ebx, %%eax \t\n"
               "pushl %%ebx   \t\n"
               "popfl     \t\n" /* restore saved flags */
               "popl %%ebx              \t\n"
               : "=a" (eax)
               : /* no input */
               );
 
  return eax & 0x200000;
}
 
L4_INLINE void
l4util_cpu_cpuid(unsigned long mode,
                 unsigned long *eax, unsigned long *ebx,
                 unsigned long *ecx, unsigned long *edx)
{
  asm volatile("pushl %%ebx      \t\n"
               "cpuid            \t\n"
               "mov %%ebx, %%esi \t\n"
               "popl %%ebx       \t\n"
               : "=a" (*eax),
                 "=S" (*ebx),
                 "=c" (*ecx),
                 "=d" (*edx)
               : "a"  (mode));
}
 
L4_INLINE unsigned int
l4util_cpu_capabilities_nocheck(void)
{
  unsigned long dummy, capability;
 
  /* get CPU capabilities */
  l4util_cpu_cpuid(1, &dummy, &dummy, &dummy, &capability);
 
  return capability;
}
 
L4_INLINE unsigned int
l4util_cpu_capabilities(void)
{
  if (!l4util_cpu_has_cpuid())
    return 0; /* CPU has not cpuid instruction */
 
  return l4util_cpu_capabilities_nocheck();
}
 
EXTERN_C_END
 
#endif