libs/wine/ldt.c

   1 /*
   2  * LDT manipulation functions
   3  *
   4  * Copyright 1993 Robert J. Amstadt
   5  * Copyright 1995 Alexandre Julliard
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  20  */
  21
  22 #include "config.h"
  23 #include "wine/port.h"
  24
  25 #include <assert.h>
  26 #include <stdlib.h>
  27 #include <stdarg.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30 #include <errno.h>
  31
  32 #include "windef.h"
  33 #include "winbase.h"
  34 #include "wine/library.h"
  35
  36 #if defined(__i386__) && !defined(__MINGW32__) && !defined(_MSC_VER)
  37
  38 #ifdef __linux__
  39
  40 #ifdef HAVE_SYS_SYSCALL_H
  41 # include <sys/syscall.h>
  42 #endif
  43
  44 struct modify_ldt_s
  45 {
  46     unsigned int  entry_number;
  47     unsigned long base_addr;
  48     unsigned int  limit;
  49     unsigned int  seg_32bit : 1;
  50     unsigned int  contents : 2;
  51     unsigned int  read_exec_only : 1;
  52     unsigned int  limit_in_pages : 1;
  53     unsigned int  seg_not_present : 1;
  54     unsigned int  usable : 1;
  55     unsigned int  garbage : 25;
  56 };
  57
  58 static inline void fill_modify_ldt_struct( struct modify_ldt_s *ptr, const LDT_ENTRY *entry )
  59 {
  60     ptr->base_addr       = (unsigned long)wine_ldt_get_base(entry);
  61     ptr->limit           = entry->LimitLow | (entry->HighWord.Bits.LimitHi << 16);
  62     ptr->seg_32bit       = entry->HighWord.Bits.Default_Big;
  63     ptr->contents        = (entry->HighWord.Bits.Type >> 2) & 3;
  64     ptr->read_exec_only  = !(entry->HighWord.Bits.Type & 2);
  65     ptr->limit_in_pages  = entry->HighWord.Bits.Granularity;
  66     ptr->seg_not_present = !entry->HighWord.Bits.Pres;
  67     ptr->usable          = entry->HighWord.Bits.Sys;
  68     ptr->garbage         = 0;
  69 }
  70
  71 static inline int modify_ldt( int func, struct modify_ldt_s *ptr, unsigned long count )
  72 {
  73     return syscall( SYS_modify_ldt, func, ptr, count );
  74 }
  75
  76 static inline int set_thread_area( struct modify_ldt_s *ptr )
  77 {
  78     return syscall( 243 /* SYS_set_thread_area */, ptr );
  79 }
  80
  81 #endif  /* linux */
  82
  83 #if defined(__svr4__) || defined(_SCO_DS)
  84 #include <sys/sysi86.h>
  85 #ifndef __sun__
  86 #include <sys/seg.h>
  87 #endif
  88 #endif
  89
  90 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__DragonFly__)
  91 #include <machine/segments.h>
  92 #include <machine/sysarch.h>
  93 #endif  /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
  94
  95 #ifdef __APPLE__
  96 #include <i386/user_ldt.h>
  97 #endif
  98
  99 /* local copy of the LDT */
 100 #ifdef __APPLE__
 101 struct __wine_ldt_copy wine_ldt_copy = { { 0, 0, 0 } };
 102 #else
 103 struct __wine_ldt_copy wine_ldt_copy;
 104 #endif
 105
 106 static const LDT_ENTRY null_entry;  /* all-zeros, used to clear LDT entries */
 107
 108 #define LDT_FIRST_ENTRY 512
 109 #define LDT_SIZE 8192
 110
 111 /* empty function for default locks */
 112 static void nop(void) { }
 113
 114 static void (*lock_ldt)(void) = nop;
 115 static void (*unlock_ldt)(void) = nop;
 116
 117
 118 static inline int is_gdt_sel( unsigned short sel ) { return !(sel & 4); }
 119
 120 /***********************************************************************
 121  *           wine_ldt_init_locking
 122  *
 123  * Set the LDT locking/unlocking functions.
 124  */
 125 void wine_ldt_init_locking( void (*lock_func)(void), void (*unlock_func)(void) )
 126 {
 127     lock_ldt = lock_func;
 128     unlock_ldt = unlock_func;
 129 }
 130
 131
 132 /***********************************************************************
 133  *           wine_ldt_get_entry
 134  *
 135  * Retrieve an LDT entry. Return a null entry if selector is not allocated.
 136  */
 137 void wine_ldt_get_entry( unsigned short sel, LDT_ENTRY *entry )
 138 {
 139     int index = sel >> 3;
 140
 141     if (is_gdt_sel(sel))
 142     {
 143         *entry = null_entry;
 144         return;
 145     }
 146     lock_ldt();
 147     if (wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_ALLOCATED)
 148     {
 149         wine_ldt_set_base(  entry, wine_ldt_copy.base[index] );
 150         wine_ldt_set_limit( entry, wine_ldt_copy.limit[index] );
 151         wine_ldt_set_flags( entry, wine_ldt_copy.flags[index] );
 152     }
 153     else *entry = null_entry;
 154     unlock_ldt();
 155 }
 156
 157
 158 /***********************************************************************
 159  *           internal_set_entry
 160  *
 161  * Set an LDT entry, without locking. For internal use only.
 162  */
 163 static int internal_set_entry( unsigned short sel, const LDT_ENTRY *entry )
 164 {
 165     int ret = 0, index = sel >> 3;
 166
 167     if (index < LDT_FIRST_ENTRY) return 0;  /* cannot modify reserved entries */
 168
 169 #ifdef linux
 170     {
 171         struct modify_ldt_s ldt_info;
 172
 173         ldt_info.entry_number = index;
 174         fill_modify_ldt_struct( &ldt_info, entry );
 175         if ((ret = modify_ldt(0x11, &ldt_info, sizeof(ldt_info))) < 0)
 176             perror( "modify_ldt" );
 177     }
 178 #elif defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__DragonFly__)
 179     {
 180         LDT_ENTRY entry_copy = *entry;
 181         /* The kernel will only let us set LDTs with user priority level */
 182         if (entry_copy.HighWord.Bits.Pres
 183             && entry_copy.HighWord.Bits.Dpl != 3)
 184                 entry_copy.HighWord.Bits.Dpl = 3;
 185         ret = i386_set_ldt(index, (union descriptor *)&entry_copy, 1);
 186         if (ret < 0)
 187         {
 188             perror("i386_set_ldt");
 189             fprintf( stderr, "Did you reconfigure the kernel with \"options USER_LDT\"?\n" );
 190             exit(1);
 191         }
 192     }
 193 #elif defined(__svr4__) || defined(_SCO_DS)
 194     {
 195         struct ssd ldt_mod;
 196         ldt_mod.sel  = sel;
 197         ldt_mod.bo   = (unsigned long)wine_ldt_get_base(entry);
 198         ldt_mod.ls   = entry->LimitLow | (entry->HighWord.Bits.LimitHi << 16);
 199         ldt_mod.acc1 = entry->HighWord.Bytes.Flags1;
 200         ldt_mod.acc2 = entry->HighWord.Bytes.Flags2 >> 4;
 201         if ((ret = sysi86(SI86DSCR, &ldt_mod)) == -1) perror("sysi86");
 202     }
 203 #elif defined(__APPLE__)
 204     if ((ret = i386_set_ldt(index, (union ldt_entry *)entry, 1)) < 0)
 205         perror("i386_set_ldt");
 206 #else
 207     fprintf( stderr, "No LDT support on this platform\n" );
 208     exit(1);
 209 #endif
 210
 211     if (ret >= 0)
 212     {
 213         wine_ldt_copy.base[index]  = wine_ldt_get_base(entry);
 214         wine_ldt_copy.limit[index] = wine_ldt_get_limit(entry);
 215         wine_ldt_copy.flags[index] = (entry->HighWord.Bits.Type |
 216                                  (entry->HighWord.Bits.Default_Big ? WINE_LDT_FLAGS_32BIT : 0) |
 217                                  (wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_ALLOCATED));
 218     }
 219     return ret;
 220 }
 221
 222
 223 /***********************************************************************
 224  *           wine_ldt_set_entry
 225  *
 226  * Set an LDT entry.
 227  */
 228 int wine_ldt_set_entry( unsigned short sel, const LDT_ENTRY *entry )
 229 {
 230     int ret;
 231
 232     lock_ldt();
 233     ret = internal_set_entry( sel, entry );
 234     unlock_ldt();
 235     return ret;
 236 }
 237
 238
 239 /***********************************************************************
 240  *           wine_ldt_is_system
 241  *
 242  * Check if the selector is a system selector (i.e. not managed by Wine).
 243  */
 244 int wine_ldt_is_system( unsigned short sel )
 245 {
 246     return is_gdt_sel(sel) || ((sel >> 3) < LDT_FIRST_ENTRY);
 247 }
 248
 249
 250 /***********************************************************************
 251  *           wine_ldt_get_ptr
 252  *
 253  * Convert a segment:offset pair to a linear pointer.
 254  * Note: we don't lock the LDT since this has to be fast.
 255  */
 256 void *wine_ldt_get_ptr( unsigned short sel, unsigned long offset )
 257 {
 258     int index;
 259
 260     if (is_gdt_sel(sel))  /* GDT selector */
 261         return (void *)offset;
 262     if ((index = (sel >> 3)) < LDT_FIRST_ENTRY)  /* system selector */
 263         return (void *)offset;
 264     if (!(wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_32BIT)) offset &= 0xffff;
 265     return (char *)wine_ldt_copy.base[index] + offset;
 266 }
 267
 268
 269 /***********************************************************************
 270  *           wine_ldt_alloc_entries
 271  *
 272  * Allocate a number of consecutive ldt entries, without setting the LDT contents.
 273  * Return a selector for the first entry.
 274  */
 275 unsigned short wine_ldt_alloc_entries( int count )
 276 {
 277     int i, index, size = 0;
 278
 279     if (count <= 0) return 0;
 280     lock_ldt();
 281     for (i = LDT_FIRST_ENTRY; i < LDT_SIZE; i++)
 282     {
 283         if (wine_ldt_copy.flags[i] & WINE_LDT_FLAGS_ALLOCATED) size = 0;
 284         else if (++size >= count)  /* found a large enough block */
 285         {
 286             index = i - size + 1;
 287
 288             /* mark selectors as allocated */
 289             for (i = 0; i < count; i++) wine_ldt_copy.flags[index + i] |= WINE_LDT_FLAGS_ALLOCATED;
 290             unlock_ldt();
 291             return (index << 3) | 7;
 292         }
 293     }
 294     unlock_ldt();
 295     return 0;
 296 }
 297
 298
 299 /***********************************************************************
 300  *           wine_ldt_realloc_entries
 301  *
 302  * Reallocate a number of consecutive ldt entries, without changing the LDT contents.
 303  * Return a selector for the first entry.
 304  */
 305 unsigned short wine_ldt_realloc_entries( unsigned short sel, int oldcount, int newcount )
 306 {
 307     int i;
 308
 309     if (oldcount < newcount)  /* we need to add selectors */
 310     {
 311         int index = sel >> 3;
 312
 313         lock_ldt();
 314         /* check if the next selectors are free */
 315         if (index + newcount > LDT_SIZE) i = oldcount;
 316         else
 317             for (i = oldcount; i < newcount; i++)
 318                 if (wine_ldt_copy.flags[index+i] & WINE_LDT_FLAGS_ALLOCATED) break;
 319
 320         if (i < newcount)  /* they are not free */
 321         {
 322             wine_ldt_free_entries( sel, oldcount );
 323             sel = wine_ldt_alloc_entries( newcount );
 324         }
 325         else  /* mark the selectors as allocated */
 326         {
 327             for (i = oldcount; i < newcount; i++)
 328                 wine_ldt_copy.flags[index+i] |= WINE_LDT_FLAGS_ALLOCATED;
 329         }
 330         unlock_ldt();
 331     }
 332     else if (oldcount > newcount) /* we need to remove selectors */
 333     {
 334         wine_ldt_free_entries( sel + (newcount << 3), newcount - oldcount );
 335     }
 336     return sel;
 337 }
 338
 339
 340 /***********************************************************************
 341  *           wine_ldt_free_entries
 342  *
 343  * Free a number of consecutive ldt entries and clear their contents.
 344  */
 345 void wine_ldt_free_entries( unsigned short sel, int count )
 346 {
 347     int index;
 348
 349     lock_ldt();
 350     for (index = sel >> 3; count > 0; count--, index++)
 351     {
 352         internal_set_entry( sel, &null_entry );
 353         wine_ldt_copy.flags[index] = 0;
 354     }
 355     unlock_ldt();
 356 }
 357
 358
 359 static int global_fs_sel = -1;  /* global selector for %fs shared among all threads */
 360
 361 /***********************************************************************
 362  *           wine_ldt_alloc_fs
 363  *
 364  * Allocate an LDT entry for a %fs selector, reusing a global
 365  * GDT selector if possible. Return the selector value.
 366  */
 367 unsigned short wine_ldt_alloc_fs(void)
 368 {
 369     if (global_fs_sel == -1)
 370     {
 371 #ifdef __linux__
 372         struct modify_ldt_s ldt_info;
 373         int ret;
 374
 375         /* the preloader may have allocated it already */
 376         global_fs_sel = wine_get_fs();
 377         if (global_fs_sel && is_gdt_sel(global_fs_sel)) return global_fs_sel;
 378
 379         ldt_info.entry_number = -1;
 380         fill_modify_ldt_struct( &ldt_info, &null_entry );
 381         if ((ret = set_thread_area( &ldt_info ) < 0))
 382         {
 383             global_fs_sel = 0;  /* don't try it again */
 384             if (errno != ENOSYS) perror( "set_thread_area" );
 385         }
 386         else global_fs_sel = (ldt_info.entry_number << 3) | 3;
 387 #elif defined(__FreeBSD__) || defined (__FreeBSD_kernel__)
 388         global_fs_sel = GSEL( GUFS_SEL, SEL_UPL );
 389 #endif
 390     }
 391     if (global_fs_sel > 0) return global_fs_sel;
 392     return wine_ldt_alloc_entries( 1 );
 393 }
 394
 395
 396 /***********************************************************************
 397  *           wine_ldt_init_fs
 398  *
 399  * Initialize the entry for the %fs selector of the current thread, and
 400  * set the thread %fs register.
 401  *
 402  * Note: this runs in the context of the new thread, so cannot acquire locks.
 403  */
 404 void wine_ldt_init_fs( unsigned short sel, const LDT_ENTRY *entry )
 405 {
 406     if ((sel & ~3) == (global_fs_sel & ~3))
 407     {
 408 #ifdef __linux__
 409         struct modify_ldt_s ldt_info;
 410         int ret;
 411
 412         ldt_info.entry_number = sel >> 3;
 413         fill_modify_ldt_struct( &ldt_info, entry );
 414         if ((ret = set_thread_area( &ldt_info ) < 0)) perror( "set_thread_area" );
 415 #elif defined(__FreeBSD__) || defined (__FreeBSD_kernel__) || defined(__DragonFly__)
 416         i386_set_fsbase( wine_ldt_get_base( entry ));
 417 #endif
 418     }
 419     else  /* LDT selector */
 420     {
 421         internal_set_entry( sel, entry );
 422     }
 423     wine_set_fs( sel );
 424 }
 425
 426
 427 /***********************************************************************
 428  *           wine_ldt_free_fs
 429  *
 430  * Free a %fs selector returned by wine_ldt_alloc_fs.
 431  */
 432 void wine_ldt_free_fs( unsigned short sel )
 433 {
 434     if (is_gdt_sel(sel)) return;  /* nothing to do */
 435     if (!((wine_get_fs() ^ sel) & ~3))
 436     {
 437         /* FIXME: if freeing current %fs we cannot acquire locks */
 438         wine_set_fs( 0 );
 439         internal_set_entry( sel, &null_entry );
 440         wine_ldt_copy.flags[sel >> 3] = 0;
 441     }
 442     else wine_ldt_free_entries( sel, 1 );
 443 }
 444
 445
 446 /***********************************************************************
 447  *           selector access functions
 448  */
 449 __ASM_GLOBAL_FUNC( wine_get_cs, "movw %cs,%ax\n\tret" )
 450 __ASM_GLOBAL_FUNC( wine_get_ds, "movw %ds,%ax\n\tret" )
 451 __ASM_GLOBAL_FUNC( wine_get_es, "movw %es,%ax\n\tret" )
 452 __ASM_GLOBAL_FUNC( wine_get_fs, "movw %fs,%ax\n\tret" )
 453 __ASM_GLOBAL_FUNC( wine_get_gs, "movw %gs,%ax\n\tret" )
 454 __ASM_GLOBAL_FUNC( wine_get_ss, "movw %ss,%ax\n\tret" )
 455 __ASM_GLOBAL_FUNC( wine_set_fs, "movl 4(%esp),%eax\n\tmovw %ax,%fs\n\tret" )
 456 __ASM_GLOBAL_FUNC( wine_set_gs, "movl 4(%esp),%eax\n\tmovw %ax,%gs\n\tret" )
 457
 458 #endif /* __i386__ */