boot/freeldr/freeldr/arch/i386/int386.S

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1998-2002  Brian Palmer  <brianp@sginet.com>
   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 #include <arch.h>
  25
  26 /* Only these flags are propagated into Int386() */
  27 #define FLAGS_PROP      (I386FLAG_CF | \
  28                      I386FLAG_ZF | \
  29                      I386FLAG_SF)
  30
  31 Int386_REGS:
  32
  33 Int386_eax:
  34         .long 0
  35 Int386_ebx:
  36         .long 0
  37 Int386_ecx:
  38         .long 0
  39 Int386_edx:
  40         .long 0
  41
  42 Int386_esi:
  43         .long 0
  44 Int386_edi:
  45         .long 0
  46
  47 Int386_ds:
  48         .word 0
  49 Int386_es:
  50         .word 0
  51 Int386_fs:
  52         .word 0
  53 Int386_gs:
  54         .word 0
  55
  56 Int386_eflags:
  57         .long 0
  58
  59 Int386_vector:
  60         .long 0
  61 Int386_regsin:
  62         .long 0
  63 Int386_regsout:
  64         .long 0
  65
  66 /*
  67  * int Int386(int ivec, REGS* in, REGS* out);
  68  */
  69 EXTERN(_Int386)
  70         .code32
  71
  72         /* Get the function parameters */
  73         movl    0x04(%esp),%eax
  74         movl    %eax,Int386_vector
  75         movb    %al,Int386_vector_opcode
  76         movl    0x08(%esp),%eax
  77         movl    %eax,Int386_regsin
  78         movl    0x0c(%esp),%eax
  79         movl    %eax,Int386_regsout
  80
  81         /* Save all registers + segment registers */
  82         pushw   %ds
  83         pushw   %es
  84         pushw   %fs
  85         pushw   %gs
  86         pushal
  87
  88         /* Copy the input regs to our variables */
  89         movl    $Int386_REGS,%edi
  90         movl    Int386_regsin,%esi
  91         movl    $0x24,%ecx
  92         cld
  93         rep
  94         movsb
  95
  96         call    switch_to_real
  97         .code16
  98
  99         /* Setup the registers */
 100         movw    %cs:Int386_ds,%ax
 101         movw    %ax,%ds                                 /* DS register */
 102         movw    %cs:Int386_es,%ax
 103         movw    %ax,%es                                 /* ES register */
 104         movw    %cs:Int386_fs,%ax
 105         movw    %ax,%fs                                 /* FS register */
 106         movw    %cs:Int386_gs,%ax
 107         movw    %ax,%gs                                 /* GS register */
 108
 109         /* Prepare EFLAGS for recover */
 110         pushf
 111         movw    %cs:Int386_eflags, %ax
 112         popw    %cx
 113         andw    $FLAGS_PROP, %ax
 114         andw    $~FLAGS_PROP, %cx
 115         orw             %cx, %ax
 116         pushw   %ax
 117
 118         /* Recover general purpose registers */
 119         movl    %cs:Int386_eax,%eax             /* EAX register */
 120         movl    %cs:Int386_ebx,%ebx             /* EBX register */
 121         movl    %cs:Int386_ecx,%ecx             /* ECX register */
 122         movl    %cs:Int386_edx,%edx             /* EDX register */
 123
 124         movl    %cs:Int386_esi,%esi             /* ESI register */
 125         movl    %cs:Int386_edi,%edi             /* EDI register */
 126
 127         /* Recover previously prepared flags */
 128         popf
 129
 130         /* Do not set the flags register */
 131         /* only return its value in regsout */
 132         //pushl Int386_eflags
 133         //popfl                                                 /* EFLAGS register */
 134
 135         /* Call the interrupt vector */
 136         /*int           Int386_vector*/
 137 Int386_int_opcode:
 138         .byte   0xcd
 139 Int386_vector_opcode:
 140         .byte   0x00
 141
 142         /* Save the registers */
 143         movl    %eax,%cs:Int386_eax             /* EAX register */
 144         movl    %ebx,%cs:Int386_ebx             /* EBX register */
 145         movl    %ecx,%cs:Int386_ecx             /* ECX register */
 146         movl    %edx,%cs:Int386_edx             /* EDX register */
 147
 148         movl    %esi,%cs:Int386_esi             /* ESI register */
 149         movl    %edi,%cs:Int386_edi             /* EDI register */
 150
 151         movw    %ds,%ax                                 /* DS register */
 152         movw    %ax,%cs:Int386_ds
 153         movw    %es,%ax                                 /* ES register */
 154         movw    %ax,%cs:Int386_es
 155         movw    %fs,%ax                                 /* FS register */
 156         movw    %ax,%cs:Int386_fs
 157         movw    %gs,%ax                                 /* GS register */
 158         movw    %ax,%cs:Int386_gs
 159
 160         pushf
 161         popw    %cs:Int386_eflags               /* EFLAGS register */
 162
 163         call    switch_to_prot
 164         .code32
 165
 166         /* Copy the variables to the output regs */
 167         movl    $Int386_REGS,%esi
 168         movl    Int386_regsout,%edi
 169         movl    $0x24,%ecx
 170         cld
 171         rep
 172         movsb
 173
 174         /* Restore segment and all other registers */
 175
 176
 177         popal
 178         popw    %gs
 179         popw    %fs
 180         popw    %es
 181         popw    %ds
 182
 183         /* Get return value */
 184         movl    Int386_eax,%eax
 185
 186         ret