l4/pkg/l4util/include/ARCH-x86/cpu.h

   1 /**
   2  * \file
   3  * \brief  CPU related functions
   4  *
   5  * \author Frank Mehnert <fm3@os.inf.tu-dresden.de> */
   6
   7 /*
   8  * (c) 2004-2009 Author(s)
   9  *     economic rights: Technische Universität Dresden (Germany)
  10  * This file is part of TUD:OS and distributed under the terms of the
  11  * GNU Lesser General Public License 2.1.
  12  * Please see the COPYING-LGPL-2.1 file for details.
  13  */
  14
  15 #ifndef __L4_UTIL_CPU_H
  16 #define __L4_UTIL_CPU_H
  17
  18 #include <l4/sys/compiler.h>
  19
  20 EXTERN_C_BEGIN
  21
  22 /**
  23  * \defgroup l4util_cpu CPU related functions
  24  * \ingroup l4util_api
  25  */
  26 /*@{*/
  27
  28 /**
  29  * Check whether the CPU supports the "cpuid" instruction.
  30  *
  31  * \return 1 if it has, 0 if it has not
  32  */
  33 L4_INLINE int          l4util_cpu_has_cpuid(void);
  34
  35 /**
  36  * Returns the CPU capabilities if the "cpuid" instruction is available.
  37  *
  38  * \return CPU capabilities if the "cpuid" instruction is available,
  39  *         0 if the "cpuid" instruction is not supported.
  40  */
  41 L4_INLINE unsigned int l4util_cpu_capabilities(void);
  42
  43 /**
  44  * Returns the CPU capabilities.
  45  *
  46  * \return CPU capabilities.
  47  */
  48 L4_INLINE unsigned int l4util_cpu_capabilities_nocheck(void);
  49
  50 /**
  51  * Generic CPUID access function.
  52  */
  53 L4_INLINE void
  54 l4util_cpu_cpuid(unsigned long mode,
  55                  unsigned long *eax, unsigned long *ebx,
  56                  unsigned long *ecx, unsigned long *edx);
  57
  58 /*@}*/
  59 static inline void
  60 l4util_cpu_pause(void)
  61 {
  62   __asm__ __volatile__ ("rep; nop");
  63 }
  64
  65 L4_INLINE int
  66 l4util_cpu_has_cpuid(void)
  67 {
  68   unsigned long eax;
  69
  70   asm volatile("pushl %%ebx             \t\n"
  71                "pushfl                  \t\n"
  72                "popl %%eax              \t\n" /* get eflags */
  73                "movl %%eax, %%ebx       \t\n" /* save it */
  74                "xorl $0x200000, %%eax   \t\n" /* toggle ID bit */
  75                "pushl %%eax             \t\n"
  76                "popfl                   \t\n" /* set again */
  77                "pushfl                  \t\n"
  78                "popl %%eax              \t\n" /* get it again */
  79                "xorl %%eax, %%ebx       \t\n"
  80                "pushl %%ebx             \t\n"
  81                "popfl                   \t\n" /* restore saved flags */
  82                "popl %%ebx              \t\n"
  83                : "=a" (eax)
  84                : /* no input */
  85                );
  86
  87   return eax & 0x200000;
  88 }
  89
  90 L4_INLINE void
  91 l4util_cpu_cpuid(unsigned long mode,
  92                  unsigned long *eax, unsigned long *ebx,
  93                  unsigned long *ecx, unsigned long *edx)
  94 {
  95   asm volatile("pushl %%ebx      \t\n"
  96                "cpuid            \t\n"
  97                "mov %%ebx, %[b]  \t\n"
  98                "popl %%ebx       \t\n"
  99                :     "=a" (*eax),
 100                  [b] "=m" (*ebx),
 101                      "=c" (*ecx),
 102                      "=d" (*edx)
 103                : "a"  (mode)
 104                );
 105 }
 106
 107 L4_INLINE unsigned int
 108 l4util_cpu_capabilities_nocheck(void)
 109 {
 110   unsigned long dummy, capability;
 111
 112   /* get CPU capabilities */
 113   l4util_cpu_cpuid(1, &dummy, &dummy, &dummy, &capability);
 114
 115   return capability;
 116 }
 117
 118 L4_INLINE unsigned int
 119 l4util_cpu_capabilities(void)
 120 {
 121   if (!l4util_cpu_has_cpuid())
 122     return 0; /* CPU has not cpuid instruction */
 123
 124   return l4util_cpu_capabilities_nocheck();
 125 }
 126
 127 EXTERN_C_END
 128
 129 #endif
 130