dlls/winedos/himem.c

   1 /*
   2  * DOS upper memory management.
   3  *
   4  * Copyright 2002 Jukka Heinonen
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  */
  20
  21 #include "dosexe.h"
  22 #include "wine/debug.h"
  23
  24 WINE_DEFAULT_DEBUG_CHANNEL(dosmem);
  25
  26 /*
  27  * Wine DOS memory layout above 640k:
  28  *
  29  *   a0000 - affff : VGA graphics         (vga.c)
  30  *   b0000 - bffff : Monochrome text      (unused)
  31  *   b8000 - bffff : VGA text             (vga.c)
  32  *   c0000 - cffff : EMS frame            (int67.c)
  33  *   d0000 - effff : Free memory for UMBs (himem.c)
  34  *   f0000 - fffff : BIOS stuff           (msdos/dosmem.c)
  35  *  100000 -10ffff : High memory area     (unused)
  36  */
  37
  38 /*
  39  * Table of real mode segments and protected mode selectors
  40  * for code stubs and other miscellaneous storage.
  41  */
  42 struct DPMI_segments *DOSVM_dpmi_segments = NULL;
  43
  44 /*
  45  * First and last address available for upper memory blocks.
  46  */
  47 #define DOSVM_UMB_BOTTOM 0xd0000
  48 #define DOSVM_UMB_TOP    0xeffff
  49
  50 /*
  51  * First free address for upper memory blocks.
  52  */
  53 static DWORD DOSVM_umb_free = DOSVM_UMB_BOTTOM;
  54
  55
  56 /***********************************************************************
  57  *           DOSVM_AllocUMB
  58  *
  59  * Allocate upper memory block (UMB) from upper memory.
  60  * Returned pointer is aligned to 16-byte (paragraph) boundary.
  61  *
  62  * This routine is only for allocating static storage for
  63  * Wine internal uses. Allocated memory can be accessed from
  64  * real mode, memory is taken from area already mapped and reserved
  65  * by Wine and the allocation has very little memory and speed
  66  * overhead. Use of this routine also preserves precious DOS
  67  * conventional memory.
  68  */
  69 LPVOID DOSVM_AllocUMB( DWORD size )
  70 {
  71   LPVOID ptr = (LPVOID)DOSVM_umb_free;
  72
  73   size = ((size + 15) >> 4) << 4;
  74
  75   if(DOSVM_umb_free + size - 1 > DOSVM_UMB_TOP) {
  76     ERR("Out of upper memory area.\n");
  77     return 0;
  78   }
  79
  80   DOSVM_umb_free += size;
  81   return ptr;
  82 }
  83
  84
  85 /**********************************************************************
  86  *          alloc_selector
  87  *
  88  * Allocate a selector corresponding to a real mode address.
  89  * size must be < 64k.
  90  */
  91 static WORD alloc_selector( void *base, DWORD size, unsigned char flags )
  92 {
  93     WORD sel = wine_ldt_alloc_entries( 1 );
  94
  95     if (sel)
  96     {
  97         LDT_ENTRY entry;
  98         wine_ldt_set_base( &entry, base );
  99         wine_ldt_set_limit( &entry, size - 1 );
 100         wine_ldt_set_flags( &entry, flags );
 101         wine_ldt_set_entry( sel, &entry );
 102     }
 103     return sel;
 104 }
 105
 106
 107 /***********************************************************************
 108  *           DOSVM_AllocCodeUMB
 109  *
 110  * Allocate upper memory block for storing code stubs.
 111  * Initializes real mode segment and 16-bit protected mode selector
 112  * for the allocated code block.
 113  *
 114  * FIXME: should allocate a single PM selector for the whole UMB range.
 115  */
 116 LPVOID DOSVM_AllocCodeUMB( DWORD size, WORD *segment, WORD *selector )
 117 {
 118   LPVOID ptr = DOSVM_AllocUMB( size );
 119
 120   if (segment)
 121     *segment = (DWORD)ptr >> 4;
 122
 123   if (selector)
 124     *selector = alloc_selector( ptr, size, WINE_LDT_FLAGS_CODE );
 125
 126   return ptr;
 127 }
 128
 129
 130 /***********************************************************************
 131  *           DOSVM_AllocDataUMB
 132  *
 133  * Allocate upper memory block for storing data.
 134  * Initializes real mode segment and 16-bit protected mode selector
 135  * for the allocated data block.
 136  */
 137 LPVOID DOSVM_AllocDataUMB( DWORD size, WORD *segment, WORD *selector )
 138 {
 139   LPVOID ptr = DOSVM_AllocUMB( size );
 140
 141   if (segment)
 142     *segment = (DWORD)ptr >> 4;
 143
 144   if (selector)
 145     *selector = alloc_selector( ptr, size, WINE_LDT_FLAGS_DATA );
 146
 147   return ptr;
 148 }
 149
 150
 151 /***********************************************************************
 152  *           DOSVM_InitSegments
 153  *
 154  * Initializes DOSVM_dpmi_segments. Allocates required memory and
 155  * sets up segments and selectors for accessing the memory.
 156  */
 157 void DOSVM_InitSegments( void )
 158 {
 159     LPSTR ptr;
 160     int   i;
 161
 162     static const char wrap_code[]={
 163      0xCD,0x31, /* int $0x31 */
 164      0xCB       /* lret */
 165     };
 166
 167     static const char enter_xms[]=
 168     {
 169         /* XMS hookable entry point */
 170         0xEB,0x03,           /* jmp entry */
 171         0x90,0x90,0x90,      /* nop;nop;nop */
 172                              /* entry: */
 173         /* real entry point */
 174         /* for simplicity, we'll just use the same hook as DPMI below */
 175         0xCD,0x31,           /* int $0x31 */
 176         0xCB                 /* lret */
 177     };
 178
 179     static const char enter_pm[]=
 180     {
 181         0x50,                /* pushw %ax */
 182         0x52,                /* pushw %dx */
 183         0x55,                /* pushw %bp */
 184         0x89,0xE5,           /* movw %sp,%bp */
 185         /* get return CS */
 186         0x8B,0x56,0x08,      /* movw 8(%bp),%dx */
 187         /* just call int 31 here to get into protected mode... */
 188         /* it'll check whether it was called from dpmi_seg... */
 189         0xCD,0x31,           /* int $0x31 */
 190         /* we are now in the context of a 16-bit relay call */
 191         /* need to fixup our stack;
 192          * 16-bit relay return address will be lost,
 193          * but we won't worry quite yet
 194          */
 195         0x8E,0xD0,           /* movw %ax,%ss */
 196         0x66,0x0F,0xB7,0xE5, /* movzwl %bp,%esp */
 197         /* set return CS */
 198         0x89,0x56,0x08,      /* movw %dx,8(%bp) */
 199         0x5D,                /* popw %bp */
 200         0x5A,                /* popw %dx */
 201         0x58,                /* popw %ax */
 202         0xfb,                /* sti, enable and check virtual interrupts */
 203         0xCB                 /* lret */
 204     };
 205
 206     static const char relay[]=
 207     {
 208         0xca, 0x04, 0x00, /* 16-bit far return and pop 4 bytes (relay void* arg) */
 209         0xcd, 0x31,       /* int 31 */
 210         0xfb, 0x66, 0xcb  /* sti and 32-bit far return */
 211     };
 212
 213     /*
 214      * Allocate pointer array.
 215      */
 216     DOSVM_dpmi_segments = DOSVM_AllocUMB( sizeof(struct DPMI_segments) );
 217
 218     /*
 219      * RM / offset 0: Exit from real mode.
 220      * RM / offset 2: Points to lret opcode.
 221      */
 222     ptr = DOSVM_AllocCodeUMB( sizeof(wrap_code),
 223                               &DOSVM_dpmi_segments->wrap_seg, 0 );
 224     memcpy( ptr, wrap_code, sizeof(wrap_code) );
 225
 226     /*
 227      * RM / offset 0: XMS driver entry.
 228      */
 229     ptr = DOSVM_AllocCodeUMB( sizeof(enter_xms),
 230                               &DOSVM_dpmi_segments->xms_seg, 0 );
 231     memcpy( ptr, enter_xms, sizeof(enter_xms) );
 232
 233     /*
 234      * RM / offset 0: Switch to DPMI.
 235      * PM / offset 8: DPMI raw mode switch.
 236      */
 237     ptr = DOSVM_AllocCodeUMB( sizeof(enter_pm),
 238                               &DOSVM_dpmi_segments->dpmi_seg,
 239                               &DOSVM_dpmi_segments->dpmi_sel );
 240     memcpy( ptr, enter_pm, sizeof(enter_pm) );
 241
 242     /*
 243      * PM / offset N*6: Interrupt N in DPMI32.
 244      */
 245     ptr = DOSVM_AllocCodeUMB( 6 * 256,
 246                               0, &DOSVM_dpmi_segments->int48_sel );
 247     for(i=0; i<256; i++) {
 248         /*
 249          * Each 32-bit interrupt handler is 6 bytes:
 250          * 0xCD,<i>            = int <i> (nested 16-bit interrupt)
 251          * 0x66,0xCA,0x04,0x00 = ret 4   (32-bit far return and pop 4 bytes / eflags)
 252          */
 253         ptr[i * 6 + 0] = 0xCD;
 254         ptr[i * 6 + 1] = i;
 255         ptr[i * 6 + 2] = 0x66;
 256         ptr[i * 6 + 3] = 0xCA;
 257         ptr[i * 6 + 4] = 0x04;
 258         ptr[i * 6 + 5] = 0x00;
 259     }
 260
 261     /*
 262      * PM / offset N*5: Interrupt N in 16-bit protected mode.
 263      */
 264     ptr = DOSVM_AllocCodeUMB( 5 * 256,
 265                               0, &DOSVM_dpmi_segments->int16_sel );
 266     for(i=0; i<256; i++) {
 267         /*
 268          * Each 16-bit interrupt handler is 5 bytes:
 269          * 0xCD,<i>       = int <i> (interrupt)
 270          * 0xCA,0x02,0x00 = ret 2   (16-bit far return and pop 2 bytes / eflags)
 271          */
 272         ptr[i * 5 + 0] = 0xCD;
 273         ptr[i * 5 + 1] = i;
 274         ptr[i * 5 + 2] = 0xCA;
 275         ptr[i * 5 + 3] = 0x02;
 276         ptr[i * 5 + 4] = 0x00;
 277     }
 278
 279     /*
 280      * PM / offset 0: Stub where __wine_call_from_16_regs returns.
 281      * PM / offset 3: Stub which swaps back to 32-bit application code/stack.
 282      * PM / offset 5: Stub which enables interrupts
 283      */
 284     ptr = DOSVM_AllocCodeUMB( sizeof(relay),
 285                               0,  &DOSVM_dpmi_segments->relay_code_sel);
 286     memcpy( ptr, relay, sizeof(relay) );
 287
 288     /*
 289      * Space for 16-bit stack used by relay code.
 290      */
 291     ptr = DOSVM_AllocDataUMB( DOSVM_RELAY_DATA_SIZE,
 292                               0, &DOSVM_dpmi_segments->relay_data_sel);
 293     memset( ptr, 0, DOSVM_RELAY_DATA_SIZE );
 294
 295     /*
 296      * As we store code in UMB we should make sure it is executable
 297      */
 298     VirtualProtect((void *)DOSVM_UMB_BOTTOM, DOSVM_UMB_TOP - DOSVM_UMB_BOTTOM, PAGE_EXECUTE_READWRITE, NULL);
 299 }