palacios/src/palacios/vmm_decoder.c

   1 /*
   2  * This file is part of the Palacios Virtual Machine Monitor developed
   3  * by the V3VEE Project with funding from the United States National
   4  * Science Foundation and the Department of Energy.
   5  *
   6  * The V3VEE Project is a joint project between Northwestern University
   7  * and the University of New Mexico.  You can find out more at
   8  * http://www.v3vee.org
   9  *
  10  * Copyright (c) 2008, Jack Lange <jarusl@cs.northwestern.edu>
  11  * Copyright (c) 2008, The V3VEE Project <http://www.v3vee.org>
  12  * All rights reserved.
  13  *
  14  * Author: Jack Lange <jarusl@cs.northwestern.edu>
  15  *
  16  * This is free software.  You are permitted to use,
  17  * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
  18  */
  19
  20
  21 #include <palacios/vmm_decoder.h>
  22
  23
  24
  25
  26
  27 void v3_get_prefixes(uchar_t * instr, struct x86_prefixes * prefixes) {
  28     while (1) {
  29         switch (*instr) {
  30             case 0xF0:      // lock
  31                 prefixes->lock = 1;
  32                 break;
  33
  34             case 0xF2:      // REPNE/REPNZ
  35                 prefixes->repnz = 1;
  36                 prefixes->repne = 1;
  37                 break;
  38
  39             case 0xF3:      // REP or REPE/REPZ
  40                 prefixes->rep = 1;
  41                 prefixes->repe = 1;
  42                 prefixes->repz = 1;
  43                 break;
  44
  45             case 0x2E:      // CS override or Branch hint not taken (with Jcc instrs)
  46                 prefixes->cs_override = 1;
  47                 prefixes->br_not_taken = 1;
  48                 break;
  49
  50             case 0x36:      // SS override
  51                 prefixes->ss_override = 1;
  52                 break;
  53
  54             case 0x3E:      // DS override or Branch hint taken (with Jcc instrs)
  55                 prefixes->ds_override = 1;
  56                 prefixes->br_taken = 1;
  57                 break;
  58
  59             case 0x26:      // ES override
  60                 prefixes->es_override = 1;
  61                 break;
  62
  63             case 0x64:      // FS override
  64                 prefixes->fs_override = 1;
  65                 break;
  66
  67             case 0x65:      // GS override
  68                 prefixes->gs_override = 1;
  69                 break;
  70
  71             case 0x66:      // operand size override
  72                 prefixes->op_size = 1;
  73                 break;
  74
  75             case 0x67:    // address size override
  76                 prefixes->addr_size = 1;
  77                 break;
  78
  79             default:
  80                 return;
  81         }
  82
  83         instr++;
  84     }
  85
  86 }
  87
  88 void v3_strip_rep_prefix(uchar_t * instr, int length) {
  89     int read_ctr = 0;
  90     int write_ctr = 0;
  91     int found = 0;
  92
  93     while (read_ctr < length) {
  94         if ((!found) &&
  95             ( (instr[read_ctr] == 0xF2) ||
  96               (instr[read_ctr] == 0xF3))) {
  97             read_ctr++;
  98             found = 1;
  99         } else {
 100             instr[write_ctr] = instr[read_ctr];
 101             write_ctr++;
 102             read_ctr++;
 103         }
 104     }
 105 }