boot/freeldr/freeldr/arch/amd64/i386cpu.S

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 2003  Eric Kohl
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License along
  16  *  with this program; if not, write to the Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20         .text
  21         .code16
  22
  23 #define ASM
  24
  25 #include <arch.h>
  26
  27 /*
  28  * U32 CpuidSupported(VOID);
  29  *
  30  * RETURNS:
  31  *    0x00000001: CPU supports the CPUID instruction
  32  *    0x00000300: Found 80386 CPU
  33  *    0x00000400: Found 80486 CPU without CPUID support
  34  */
  35
  36 EXTERN(CpuidSupported)
  37         .code32
  38
  39         pushl   %ecx                    /* save ECX */
  40
  41         pushfl                          /* push original EFLAGS */
  42         popl    %eax                    /* get original EFLAGS */
  43         movl    %eax,%ecx               /* save original EFLAGS */
  44         xorl    $0x40000,%eax           /* flip AC bit in EFLAGS */
  45         pushl   %eax                    /* save new EFLAGS value on stack */
  46         popfl                           /* replace current EFLAGS value */
  47
  48         pushfl                          /* get new EFLAGS */
  49         popl    %eax                    /* store new EFLAGS in EAX */
  50         xorl    %ecx, %eax              /* can't toggle AC bit, processor=80386 */
  51
  52         movl    $0x300,%eax             /* return processor id */
  53         jz      NoCpuid                 /* jump if 80386 processor */
  54
  55         pushl   %ecx
  56         popfl                           /* restore AC bit in EFLAGS first */
  57
  58         movl    %ecx,%eax               /* get original EFLAGS */
  59         xorl    $0x200000,%eax          /* flip ID bit in EFLAGS */
  60         pushl   %eax                    /* save new EFLAGS value on stack */
  61         popfl                           /* replace current EFLAGS value */
  62         pushfl                          /* get new EFLAGS */
  63         popl    %eax                    /* store new EFLAGS in EAX */
  64         xorl    %ecx,%eax               /* can't toggle ID bit, */
  65
  66         movl    $0x400,%eax             /* return processor id */
  67         je      NoCpuid                 /* processor=80486 */
  68
  69         movl    $1,%eax                 /* CPUID supported */
  70
  71 NoCpuid:
  72         pushl   %ecx
  73         popfl                           /* restore EFLAGS */
  74         popl    %ecx                    /* retore ECX */
  75
  76         ret
  77
  78
  79 /*
  80  * VOID GetCpuid(U32 Level, U32 *eax, U32 *ebx, U32 *ecx, U32 *edx);
  81  */
  82
  83 EXTERN(GetCpuid)
  84         .code32
  85
  86         pushl   %ebp
  87         movl    %esp,%ebp
  88
  89         pushl   %eax
  90         pushl   %ebx
  91         pushl   %ecx
  92         pushl   %edx
  93         pushl   %esi
  94
  95         movl    0x08(%ebp),%eax
  96
  97         cpuid
  98
  99         movl    0x0C(%ebp),%esi
 100         movl    %eax,(%esi)
 101
 102         movl    0x10(%ebp),%esi
 103         movl    %ebx,(%esi)
 104
 105         movl    0x14(%ebp),%esi
 106         movl    %ecx,(%esi)
 107
 108         movl    0x18(%ebp),%esi
 109         movl    %edx,(%esi)
 110
 111         popl    %esi
 112         popl    %edx
 113         popl    %ecx
 114         popl    %ebx
 115         popl    %eax
 116
 117         movl    %ebp,%esp
 118         popl    %ebp
 119         ret
 120
 121
 122 /*
 123  * U64 RDTSC(VOID);
 124  */
 125
 126 EXTERN(RDTSC)
 127         .code32
 128         rdtsc
 129         ret
 130
 131 /* EOF */