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     int res;
  74     __asm__ __volatile__( "pushl %%ebx\n\t"
  75                           "movl %2,%%ebx\n\t"
  76                           "int $0x80\n\t"
  77                           "popl %%ebx"
  78                           : "=a" (res)
  79                           : "0" (SYS_modify_ldt),
  80                             "r" (func),
  81                             "c" (ptr),
  82                             "d" (count),
  83                             "m" (*ptr) );
  84     if (res >= 0) return res;
  85     errno = -res;
  86     return -1;
  87 }
  88
  89 static inline int set_thread_area( struct modify_ldt_s *ptr )
  90 {
  91     int res;
  92     __asm__ __volatile__( "pushl %%ebx\n\t"
  93                           "movl %3,%%ebx\n\t"
  94                           "int $0x80\n\t"
  95                           "popl %%ebx"
  96                           : "=a" (res), "=m" (*ptr)
  97                           : "0" (243) /* SYS_set_thread_area */, "q" (ptr), "m" (*ptr) );
  98     if (res >= 0) return res;
  99     errno = -res;
 100     return -1;
 101 }
 102
 103 #endif  /* linux */
 104
 105 #if defined(__svr4__) || defined(_SCO_DS)
 106 #include <sys/sysi86.h>
 107 #ifndef __sun__
 108 #include <sys/seg.h>
 109 #endif
 110 #endif
 111
 112 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__)
 113 #include <machine/segments.h>
 114 #include <machine/sysarch.h>
 115 #endif  /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
 116
 117 #ifdef __APPLE__
 118 #include <i386/user_ldt.h>
 119 #endif
 120
 121 /* local copy of the LDT */
 122 #ifdef __APPLE__
 123 struct __wine_ldt_copy wine_ldt_copy = { { 0, 0, 0 } };
 124 #else
 125 struct __wine_ldt_copy wine_ldt_copy;
 126 #endif
 127
 128 static const LDT_ENTRY null_entry;  /* all-zeros, used to clear LDT entries */
 129
 130 #define LDT_FIRST_ENTRY 512
 131 #define LDT_SIZE 8192
 132
 133 /* empty function for default locks */
 134 static void nop(void) { }
 135
 136 static void (*lock_ldt)(void) = nop;
 137 static void (*unlock_ldt)(void) = nop;
 138
 139
 140 static inline int is_gdt_sel( unsigned short sel ) { return !(sel & 4); }
 141
 142 /***********************************************************************
 143  *           wine_ldt_init_locking
 144  *
 145  * Set the LDT locking/unlocking functions.
 146  */
 147 void wine_ldt_init_locking( void (*lock_func)(void), void (*unlock_func)(void) )
 148 {
 149     lock_ldt = lock_func;
 150     unlock_ldt = unlock_func;
 151 }
 152
 153
 154 /***********************************************************************
 155  *           wine_ldt_get_entry
 156  *
 157  * Retrieve an LDT entry. Return a null entry if selector is not allocated.
 158  */
 159 void wine_ldt_get_entry( unsigned short sel, LDT_ENTRY *entry )
 160 {
 161     int index = sel >> 3;
 162
 163     if (is_gdt_sel(sel))
 164     {
 165         *entry = null_entry;
 166         return;
 167     }
 168     lock_ldt();
 169     if (wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_ALLOCATED)
 170     {
 171         wine_ldt_set_base(  entry, wine_ldt_copy.base[index] );
 172         wine_ldt_set_limit( entry, wine_ldt_copy.limit[index] );
 173         wine_ldt_set_flags( entry, wine_ldt_copy.flags[index] );
 174     }
 175     else *entry = null_entry;
 176     unlock_ldt();
 177 }
 178
 179
 180 /***********************************************************************
 181  *           internal_set_entry
 182  *
 183  * Set an LDT entry, without locking. For internal use only.
 184  */
 185 static int internal_set_entry( unsigned short sel, const LDT_ENTRY *entry )
 186 {
 187     int ret = 0, index = sel >> 3;
 188
 189     if (index < LDT_FIRST_ENTRY) return 0;  /* cannot modify reserved entries */
 190
 191 #ifdef linux
 192     {
 193         struct modify_ldt_s ldt_info;
 194
 195         ldt_info.entry_number = index;
 196         fill_modify_ldt_struct( &ldt_info, entry );
 197         if ((ret = modify_ldt(0x11, &ldt_info, sizeof(ldt_info))) < 0)
 198             perror( "modify_ldt" );
 199     }
 200 #elif defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__)
 201     {
 202         LDT_ENTRY entry_copy = *entry;
 203         /* The kernel will only let us set LDTs with user priority level */
 204         if (entry_copy.HighWord.Bits.Pres
 205             && entry_copy.HighWord.Bits.Dpl != 3)
 206                 entry_copy.HighWord.Bits.Dpl = 3;
 207         ret = i386_set_ldt(index, (union descriptor *)&entry_copy, 1);
 208         if (ret < 0)
 209         {
 210             perror("i386_set_ldt");
 211             fprintf( stderr, "Did you reconfigure the kernel with \"options USER_LDT\"?\n" );
 212             exit(1);
 213         }
 214     }
 215 #elif defined(__svr4__) || defined(_SCO_DS)
 216     {
 217         struct ssd ldt_mod;
 218         ldt_mod.sel  = sel;
 219         ldt_mod.bo   = (unsigned long)wine_ldt_get_base(entry);
 220         ldt_mod.ls   = entry->LimitLow | (entry->HighWord.Bits.LimitHi << 16);
 221         ldt_mod.acc1 = entry->HighWord.Bytes.Flags1;
 222         ldt_mod.acc2 = entry->HighWord.Bytes.Flags2 >> 4;
 223         if ((ret = sysi86(SI86DSCR, &ldt_mod)) == -1) perror("sysi86");
 224     }
 225 #elif defined(__APPLE__)
 226     if ((ret = i386_set_ldt(index, (union ldt_entry *)entry, 1)) < 0)
 227         perror("i386_set_ldt");
 228 #else
 229     fprintf( stderr, "No LDT support on this platform\n" );
 230     exit(1);
 231 #endif
 232
 233     if (ret >= 0)
 234     {
 235         wine_ldt_copy.base[index]  = wine_ldt_get_base(entry);
 236         wine_ldt_copy.limit[index] = wine_ldt_get_limit(entry);
 237         wine_ldt_copy.flags[index] = (entry->HighWord.Bits.Type |
 238                                  (entry->HighWord.Bits.Default_Big ? WINE_LDT_FLAGS_32BIT : 0) |
 239                                  (wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_ALLOCATED));
 240     }
 241     return ret;
 242 }
 243
 244
 245 /***********************************************************************
 246  *           wine_ldt_set_entry
 247  *
 248  * Set an LDT entry.
 249  */
 250 int wine_ldt_set_entry( unsigned short sel, const LDT_ENTRY *entry )
 251 {
 252     int ret;
 253
 254     lock_ldt();
 255     ret = internal_set_entry( sel, entry );
 256     unlock_ldt();
 257     return ret;
 258 }
 259
 260
 261 /***********************************************************************
 262  *           wine_ldt_is_system
 263  *
 264  * Check if the selector is a system selector (i.e. not managed by Wine).
 265  */
 266 int wine_ldt_is_system( unsigned short sel )
 267 {
 268     return is_gdt_sel(sel) || ((sel >> 3) < LDT_FIRST_ENTRY);
 269 }
 270
 271
 272 /***********************************************************************
 273  *           wine_ldt_get_ptr
 274  *
 275  * Convert a segment:offset pair to a linear pointer.
 276  * Note: we don't lock the LDT since this has to be fast.
 277  */
 278 void *wine_ldt_get_ptr( unsigned short sel, unsigned long offset )
 279 {
 280     int index;
 281
 282     if (is_gdt_sel(sel))  /* GDT selector */
 283         return (void *)offset;
 284     if ((index = (sel >> 3)) < LDT_FIRST_ENTRY)  /* system selector */
 285         return (void *)offset;
 286     if (!(wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_32BIT)) offset &= 0xffff;
 287     return (char *)wine_ldt_copy.base[index] + offset;
 288 }
 289
 290
 291 /***********************************************************************
 292  *           wine_ldt_alloc_entries
 293  *
 294  * Allocate a number of consecutive ldt entries, without setting the LDT contents.
 295  * Return a selector for the first entry.
 296  */
 297 unsigned short wine_ldt_alloc_entries( int count )
 298 {
 299     int i, index, size = 0;
 300
 301     if (count <= 0) return 0;
 302     lock_ldt();
 303     for (i = LDT_FIRST_ENTRY; i < LDT_SIZE; i++)
 304     {
 305         if (wine_ldt_copy.flags[i] & WINE_LDT_FLAGS_ALLOCATED) size = 0;
 306         else if (++size >= count)  /* found a large enough block */
 307         {
 308             index = i - size + 1;
 309
 310             /* mark selectors as allocated */
 311             for (i = 0; i < count; i++) wine_ldt_copy.flags[index + i] |= WINE_LDT_FLAGS_ALLOCATED;
 312             unlock_ldt();
 313             return (index << 3) | 7;
 314         }
 315     }
 316     unlock_ldt();
 317     return 0;
 318 }
 319
 320
 321 /***********************************************************************
 322  *           wine_ldt_realloc_entries
 323  *
 324  * Reallocate a number of consecutive ldt entries, without changing the LDT contents.
 325  * Return a selector for the first entry.
 326  */
 327 unsigned short wine_ldt_realloc_entries( unsigned short sel, int oldcount, int newcount )
 328 {
 329     int i;
 330
 331     if (oldcount < newcount)  /* we need to add selectors */
 332     {
 333         int index = sel >> 3;
 334
 335         lock_ldt();
 336         /* check if the next selectors are free */
 337         if (index + newcount > LDT_SIZE) i = oldcount;
 338         else
 339             for (i = oldcount; i < newcount; i++)
 340                 if (wine_ldt_copy.flags[index+i] & WINE_LDT_FLAGS_ALLOCATED) break;
 341
 342         if (i < newcount)  /* they are not free */
 343         {
 344             wine_ldt_free_entries( sel, oldcount );
 345             sel = wine_ldt_alloc_entries( newcount );
 346         }
 347         else  /* mark the selectors as allocated */
 348         {
 349             for (i = oldcount; i < newcount; i++)
 350                 wine_ldt_copy.flags[index+i] |= WINE_LDT_FLAGS_ALLOCATED;
 351         }
 352         unlock_ldt();
 353     }
 354     else if (oldcount > newcount) /* we need to remove selectors */
 355     {
 356         wine_ldt_free_entries( sel + (newcount << 3), newcount - oldcount );
 357     }
 358     return sel;
 359 }
 360
 361
 362 /***********************************************************************
 363  *           wine_ldt_free_entries
 364  *
 365  * Free a number of consecutive ldt entries and clear their contents.
 366  */
 367 void wine_ldt_free_entries( unsigned short sel, int count )
 368 {
 369     int index;
 370
 371     lock_ldt();
 372     for (index = sel >> 3; count > 0; count--, index++)
 373     {
 374         internal_set_entry( sel, &null_entry );
 375         wine_ldt_copy.flags[index] = 0;
 376     }
 377     unlock_ldt();
 378 }
 379
 380
 381 static int global_fs_sel = -1;  /* global selector for %fs shared among all threads */
 382
 383 /***********************************************************************
 384  *           wine_ldt_alloc_fs
 385  *
 386  * Allocate an LDT entry for a %fs selector, reusing a global
 387  * GDT selector if possible. Return the selector value.
 388  */
 389 unsigned short wine_ldt_alloc_fs(void)
 390 {
 391     if (global_fs_sel == -1)
 392     {
 393 #ifdef __linux__
 394         struct modify_ldt_s ldt_info;
 395         int ret;
 396
 397         /* the preloader may have allocated it already */
 398         global_fs_sel = wine_get_fs();
 399         if (global_fs_sel && is_gdt_sel(global_fs_sel)) return global_fs_sel;
 400
 401         ldt_info.entry_number = -1;
 402         fill_modify_ldt_struct( &ldt_info, &null_entry );
 403         if ((ret = set_thread_area( &ldt_info ) < 0))
 404         {
 405             global_fs_sel = 0;  /* don't try it again */
 406             if (errno != ENOSYS) perror( "set_thread_area" );
 407         }
 408         else global_fs_sel = (ldt_info.entry_number << 3) | 3;
 409 #elif defined(__FreeBSD__)
 410         global_fs_sel = GSEL( GUFS_SEL, SEL_UPL );
 411 #endif
 412     }
 413     if (global_fs_sel > 0) return global_fs_sel;
 414     return wine_ldt_alloc_entries( 1 );
 415 }
 416
 417
 418 /***********************************************************************
 419  *           wine_ldt_init_fs
 420  *
 421  * Initialize the entry for the %fs selector of the current thread, and
 422  * set the thread %fs register.
 423  *
 424  * Note: this runs in the context of the new thread, so cannot acquire locks.
 425  */
 426 void wine_ldt_init_fs( unsigned short sel, const LDT_ENTRY *entry )
 427 {
 428     if ((sel & ~3) == (global_fs_sel & ~3))
 429     {
 430 #ifdef __linux__
 431         struct modify_ldt_s ldt_info;
 432         int ret;
 433
 434         ldt_info.entry_number = sel >> 3;
 435         fill_modify_ldt_struct( &ldt_info, entry );
 436         if ((ret = set_thread_area( &ldt_info ) < 0)) perror( "set_thread_area" );
 437 #elif defined(__FreeBSD__)
 438         i386_set_fsbase( wine_ldt_get_base( entry ));
 439 #endif
 440     }
 441     else  /* LDT selector */
 442     {
 443         internal_set_entry( sel, entry );
 444     }
 445     wine_set_fs( sel );
 446 }
 447
 448
 449 /***********************************************************************
 450  *           wine_ldt_free_fs
 451  *
 452  * Free a %fs selector returned by wine_ldt_alloc_fs.
 453  */
 454 void wine_ldt_free_fs( unsigned short sel )
 455 {
 456     if (is_gdt_sel(sel)) return;  /* nothing to do */
 457     if (!((wine_get_fs() ^ sel) & ~3))
 458     {
 459         /* FIXME: if freeing current %fs we cannot acquire locks */
 460         wine_set_fs( 0 );
 461         internal_set_entry( sel, &null_entry );
 462         wine_ldt_copy.flags[sel >> 3] = 0;
 463     }
 464     else wine_ldt_free_entries( sel, 1 );
 465 }
 466
 467
 468 /***********************************************************************
 469  *           selector access functions
 470  */
 471 __ASM_GLOBAL_FUNC( wine_get_cs, "movw %cs,%ax\n\tret" )
 472 __ASM_GLOBAL_FUNC( wine_get_ds, "movw %ds,%ax\n\tret" )
 473 __ASM_GLOBAL_FUNC( wine_get_es, "movw %es,%ax\n\tret" )
 474 __ASM_GLOBAL_FUNC( wine_get_fs, "movw %fs,%ax\n\tret" )
 475 __ASM_GLOBAL_FUNC( wine_get_gs, "movw %gs,%ax\n\tret" )
 476 __ASM_GLOBAL_FUNC( wine_get_ss, "movw %ss,%ax\n\tret" )
 477 __ASM_GLOBAL_FUNC( wine_set_fs, "movl 4(%esp),%eax\n\tmovw %ax,%fs\n\tret" )
 478 __ASM_GLOBAL_FUNC( wine_set_gs, "movl 4(%esp),%eax\n\tmovw %ax,%gs\n\tret" )
 479
 480 #endif /* __i386__ */