src/arch/i386/core/cpu.c

   1 #include <stdint.h>
   2 #include <string.h>
   3 #include <cpu.h>
   4
   5 /** @file
   6  *
   7  * CPU identification
   8  *
   9  */
  10
  11 /**
  12  * Test to see if CPU flag is changeable
  13  *
  14  * @v flag              Flag to test
  15  * @ret can_change      Flag is changeable
  16  */
  17 static inline int flag_is_changeable ( unsigned int flag ) {
  18         uint32_t f1, f2;
  19
  20         __asm__ ( "pushfl\n\t"
  21                   "pushfl\n\t"
  22                   "popl %0\n\t"
  23                   "movl %0,%1\n\t"
  24                   "xorl %2,%0\n\t"
  25                   "pushl %0\n\t"
  26                   "popfl\n\t"
  27                   "pushfl\n\t"
  28                   "popl %0\n\t"
  29                   "popfl\n\t"
  30                   : "=&r" ( f1 ), "=&r" ( f2 )
  31                   : "ir" ( flag ) );
  32
  33         return ( ( ( f1 ^ f2 ) & flag ) != 0 );
  34 }
  35
  36 /**
  37  * Get CPU information
  38  *
  39  * @v cpu               CPU information structure to fill in
  40  */
  41 void get_cpuinfo ( struct cpuinfo_x86 *cpu ) {
  42         unsigned int cpuid_level;
  43         unsigned int cpuid_extlevel;
  44         unsigned int discard_1, discard_2, discard_3;
  45
  46         memset ( cpu, 0, sizeof ( *cpu ) );
  47
  48         /* Check for CPUID instruction */
  49         if ( ! flag_is_changeable ( X86_EFLAGS_ID ) ) {
  50                 DBG ( "CPUID not supported\n" );
  51                 return;
  52         }
  53
  54         /* Get features, if present */
  55         cpuid ( 0x00000000, &cpuid_level, &discard_1,
  56                 &discard_2, &discard_3 );
  57         if ( cpuid_level >= 0x00000001 ) {
  58                 cpuid ( 0x00000001, &discard_1, &discard_2,
  59                         &discard_3, &cpu->features );
  60         } else {
  61                 DBG ( "CPUID cannot return capabilities\n" );
  62         }
  63
  64         /* Get 64-bit features, if present */
  65         cpuid ( 0x80000000, &cpuid_extlevel, &discard_1,
  66                 &discard_2, &discard_3 );
  67         if ( ( cpuid_extlevel & 0xffff0000 ) == 0x80000000 ) {
  68                 if ( cpuid_extlevel >= 0x80000001 ) {
  69                         cpuid ( 0x80000001, &discard_1, &discard_2,
  70                                 &discard_3, &cpu->amd_features );
  71                 }
  72         }
  73 }