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 #include "wine/asm.h"
  36
  37 #ifdef __i386__
  38
  39 #ifdef __linux__
  40
  41 #ifdef HAVE_SYS_SYSCALL_H
  42 # include <sys/syscall.h>
  43 #endif
  44
  45 struct modify_ldt_s
  46 {
  47     unsigned int  entry_number;
  48     unsigned long base_addr;
  49     unsigned int  limit;
  50     unsigned int  seg_32bit : 1;
  51     unsigned int  contents : 2;
  52     unsigned int  read_exec_only : 1;
  53     unsigned int  limit_in_pages : 1;
  54     unsigned int  seg_not_present : 1;
  55     unsigned int  usable : 1;
  56     unsigned int  garbage : 25;
  57 };
  58
  59 static inline void fill_modify_ldt_struct( struct modify_ldt_s *ptr, const LDT_ENTRY *entry )
  60 {
  61     ptr->base_addr       = (unsigned long)wine_ldt_get_base(entry);
  62     ptr->limit           = entry->LimitLow | (entry->HighWord.Bits.LimitHi << 16);
  63     ptr->seg_32bit       = entry->HighWord.Bits.Default_Big;
  64     ptr->contents        = (entry->HighWord.Bits.Type >> 2) & 3;
  65     ptr->read_exec_only  = !(entry->HighWord.Bits.Type & 2);
  66     ptr->limit_in_pages  = entry->HighWord.Bits.Granularity;
  67     ptr->seg_not_present = !entry->HighWord.Bits.Pres;
  68     ptr->usable          = entry->HighWord.Bits.Sys;
  69     ptr->garbage         = 0;
  70 }
  71
  72 static inline int modify_ldt( int func, struct modify_ldt_s *ptr, unsigned long count )
  73 {
  74     return syscall( 123 /* SYS_modify_ldt */, func, ptr, count );
  75 }
  76
  77 static inline int set_thread_area( struct modify_ldt_s *ptr )
  78 {
  79     return syscall( 243 /* SYS_set_thread_area */, ptr );
  80 }
  81
  82 #endif  /* linux */
  83
  84 #if defined(__svr4__) || defined(_SCO_DS)
  85 #include <sys/sysi86.h>
  86 #ifndef __sun__
  87 #include <sys/seg.h>
  88 #endif
  89 #endif
  90
  91 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__DragonFly__)
  92 #include <machine/segments.h>
  93 #include <machine/sysarch.h>
  94 #endif  /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
  95
  96 #ifdef __GNU__
  97 #include <mach/i386/mach_i386.h>
  98 #include <mach/mach_traps.h>
  99 #endif
 100
 101 #ifdef __APPLE__
 102 #include <i386/user_ldt.h>
 103 #endif
 104
 105 /* local copy of the LDT */
 106 #ifdef __APPLE__
 107 struct __wine_ldt_copy wine_ldt_copy = { { 0, 0, 0 } };
 108 #else
 109 struct __wine_ldt_copy wine_ldt_copy;
 110 #endif
 111
 112 static const LDT_ENTRY null_entry;  /* all-zeros, used to clear LDT entries */
 113
 114 #define LDT_FIRST_ENTRY 512
 115 #define LDT_SIZE 8192
 116
 117 /* empty function for default locks */
 118 static void nop(void) { }
 119
 120 static void (*lock_ldt)(void) = nop;
 121 static void (*unlock_ldt)(void) = nop;
 122
 123
 124 static inline int is_gdt_sel( unsigned short sel ) { return !(sel & 4); }
 125
 126 /***********************************************************************
 127  *           wine_ldt_init_locking
 128  *
 129  * Set the LDT locking/unlocking functions.
 130  */
 131 void wine_ldt_init_locking( void (*lock_func)(void), void (*unlock_func)(void) )
 132 {
 133     lock_ldt = lock_func;
 134     unlock_ldt = unlock_func;
 135 }
 136
 137
 138 /***********************************************************************
 139  *           wine_ldt_get_entry
 140  *
 141  * Retrieve an LDT entry. Return a null entry if selector is not allocated.
 142  */
 143 void wine_ldt_get_entry( unsigned short sel, LDT_ENTRY *entry )
 144 {
 145     int index = sel >> 3;
 146
 147     if (is_gdt_sel(sel))
 148     {
 149         *entry = null_entry;
 150         return;
 151     }
 152     lock_ldt();
 153     if (wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_ALLOCATED)
 154     {
 155         wine_ldt_set_base(  entry, wine_ldt_copy.base[index] );
 156         wine_ldt_set_limit( entry, wine_ldt_copy.limit[index] );
 157         wine_ldt_set_flags( entry, wine_ldt_copy.flags[index] );
 158     }
 159     else *entry = null_entry;
 160     unlock_ldt();
 161 }
 162
 163
 164 /***********************************************************************
 165  *           internal_set_entry
 166  *
 167  * Set an LDT entry, without locking. For internal use only.
 168  */
 169 static int internal_set_entry( unsigned short sel, const LDT_ENTRY *entry )
 170 {
 171     int ret = 0, index = sel >> 3;
 172
 173     if (index < LDT_FIRST_ENTRY) return 0;  /* cannot modify reserved entries */
 174
 175 #ifdef linux
 176     {
 177         struct modify_ldt_s ldt_info;
 178
 179         ldt_info.entry_number = index;
 180         fill_modify_ldt_struct( &ldt_info, entry );
 181         if ((ret = modify_ldt(0x11, &ldt_info, sizeof(ldt_info))) < 0)
 182             perror( "modify_ldt" );
 183     }
 184 #elif defined(__NetBSD__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__DragonFly__)
 185     {
 186         LDT_ENTRY entry_copy = *entry;
 187         /* The kernel will only let us set LDTs with user priority level */
 188         if (entry_copy.HighWord.Bits.Pres
 189             && entry_copy.HighWord.Bits.Dpl != 3)
 190                 entry_copy.HighWord.Bits.Dpl = 3;
 191         ret = i386_set_ldt(index, (union descriptor *)&entry_copy, 1);
 192         if (ret < 0)
 193         {
 194             perror("i386_set_ldt");
 195             fprintf( stderr, "Did you reconfigure the kernel with \"options USER_LDT\"?\n" );
 196             exit(1);
 197         }
 198     }
 199 #elif defined(__svr4__) || defined(_SCO_DS)
 200     {
 201         struct ssd ldt_mod;
 202         ldt_mod.sel  = sel;
 203         ldt_mod.bo   = (unsigned long)wine_ldt_get_base(entry);
 204         ldt_mod.ls   = entry->LimitLow | (entry->HighWord.Bits.LimitHi << 16);
 205         ldt_mod.acc1 = entry->HighWord.Bytes.Flags1;
 206         ldt_mod.acc2 = entry->HighWord.Bytes.Flags2 >> 4;
 207         if ((ret = sysi86(SI86DSCR, &ldt_mod)) == -1) perror("sysi86");
 208     }
 209 #elif defined(__APPLE__)
 210     if ((ret = i386_set_ldt(index, (union ldt_entry *)entry, 1)) < 0)
 211         perror("i386_set_ldt");
 212 #elif defined(__GNU__)
 213     if ((ret = i386_set_ldt(mach_thread_self(), sel, (descriptor_list_t)entry, 1)) != KERN_SUCCESS)
 214         perror("i386_set_ldt");
 215 #else
 216     fprintf( stderr, "No LDT support on this platform\n" );
 217     exit(1);
 218 #endif
 219
 220     if (ret >= 0)
 221     {
 222         wine_ldt_copy.base[index]  = wine_ldt_get_base(entry);
 223         wine_ldt_copy.limit[index] = wine_ldt_get_limit(entry);
 224         wine_ldt_copy.flags[index] = (entry->HighWord.Bits.Type |
 225                                  (entry->HighWord.Bits.Default_Big ? WINE_LDT_FLAGS_32BIT : 0) |
 226                                  (wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_ALLOCATED));
 227     }
 228     return ret;
 229 }
 230
 231
 232 /***********************************************************************
 233  *           wine_ldt_set_entry
 234  *
 235  * Set an LDT entry.
 236  */
 237 int wine_ldt_set_entry( unsigned short sel, const LDT_ENTRY *entry )
 238 {
 239     int ret;
 240
 241     lock_ldt();
 242     ret = internal_set_entry( sel, entry );
 243     unlock_ldt();
 244     return ret;
 245 }
 246
 247
 248 /***********************************************************************
 249  *           wine_ldt_is_system
 250  *
 251  * Check if the selector is a system selector (i.e. not managed by Wine).
 252  */
 253 int wine_ldt_is_system( unsigned short sel )
 254 {
 255     return is_gdt_sel(sel) || ((sel >> 3) < LDT_FIRST_ENTRY);
 256 }
 257
 258
 259 /***********************************************************************
 260  *           wine_ldt_get_ptr
 261  *
 262  * Convert a segment:offset pair to a linear pointer.
 263  * Note: we don't lock the LDT since this has to be fast.
 264  */
 265 void *wine_ldt_get_ptr( unsigned short sel, unsigned long offset )
 266 {
 267     int index;
 268
 269     if (is_gdt_sel(sel))  /* GDT selector */
 270         return (void *)offset;
 271     if ((index = (sel >> 3)) < LDT_FIRST_ENTRY)  /* system selector */
 272         return (void *)offset;
 273     if (!(wine_ldt_copy.flags[index] & WINE_LDT_FLAGS_32BIT)) offset &= 0xffff;
 274     return (char *)wine_ldt_copy.base[index] + offset;
 275 }
 276
 277
 278 /***********************************************************************
 279  *           wine_ldt_alloc_entries
 280  *
 281  * Allocate a number of consecutive ldt entries, without setting the LDT contents.
 282  * Return a selector for the first entry.
 283  */
 284 unsigned short wine_ldt_alloc_entries( int count )
 285 {
 286     int i, index, size = 0;
 287
 288     if (count <= 0) return 0;
 289     lock_ldt();
 290     for (i = LDT_FIRST_ENTRY; i < LDT_SIZE; i++)
 291     {
 292         if (wine_ldt_copy.flags[i] & WINE_LDT_FLAGS_ALLOCATED) size = 0;
 293         else if (++size >= count)  /* found a large enough block */
 294         {
 295             index = i - size + 1;
 296
 297             /* mark selectors as allocated */
 298             for (i = 0; i < count; i++) wine_ldt_copy.flags[index + i] |= WINE_LDT_FLAGS_ALLOCATED;
 299             unlock_ldt();
 300             return (index << 3) | 7;
 301         }
 302     }
 303     unlock_ldt();
 304     return 0;
 305 }
 306
 307
 308 /***********************************************************************
 309  *           wine_ldt_realloc_entries
 310  *
 311  * Reallocate a number of consecutive ldt entries, without changing the LDT contents.
 312  * Return a selector for the first entry.
 313  */
 314 unsigned short wine_ldt_realloc_entries( unsigned short sel, int oldcount, int newcount )
 315 {
 316     int i;
 317
 318     if (oldcount < newcount)  /* we need to add selectors */
 319     {
 320         int index = sel >> 3;
 321
 322         lock_ldt();
 323         /* check if the next selectors are free */
 324         if (index + newcount > LDT_SIZE) i = oldcount;
 325         else
 326             for (i = oldcount; i < newcount; i++)
 327                 if (wine_ldt_copy.flags[index+i] & WINE_LDT_FLAGS_ALLOCATED) break;
 328
 329         if (i < newcount)  /* they are not free */
 330         {
 331             wine_ldt_free_entries( sel, oldcount );
 332             sel = wine_ldt_alloc_entries( newcount );
 333         }
 334         else  /* mark the selectors as allocated */
 335         {
 336             for (i = oldcount; i < newcount; i++)
 337                 wine_ldt_copy.flags[index+i] |= WINE_LDT_FLAGS_ALLOCATED;
 338         }
 339         unlock_ldt();
 340     }
 341     else if (oldcount > newcount) /* we need to remove selectors */
 342     {
 343         wine_ldt_free_entries( sel + (newcount << 3), newcount - oldcount );
 344     }
 345     return sel;
 346 }
 347
 348
 349 /***********************************************************************
 350  *           wine_ldt_free_entries
 351  *
 352  * Free a number of consecutive ldt entries and clear their contents.
 353  */
 354 void wine_ldt_free_entries( unsigned short sel, int count )
 355 {
 356     int index;
 357
 358     lock_ldt();
 359     for (index = sel >> 3; count > 0; count--, index++)
 360     {
 361         internal_set_entry( sel, &null_entry );
 362         wine_ldt_copy.flags[index] = 0;
 363     }
 364     unlock_ldt();
 365 }
 366
 367
 368 static int global_fs_sel = -1;  /* global selector for %fs shared among all threads */
 369
 370 /***********************************************************************
 371  *           wine_ldt_alloc_fs
 372  *
 373  * Allocate an LDT entry for a %fs selector, reusing a global
 374  * GDT selector if possible. Return the selector value.
 375  */
 376 unsigned short wine_ldt_alloc_fs(void)
 377 {
 378     if (global_fs_sel == -1)
 379     {
 380 #ifdef __linux__
 381         struct modify_ldt_s ldt_info;
 382         int ret;
 383
 384         /* the preloader may have allocated it already */
 385         global_fs_sel = wine_get_fs();
 386         if (global_fs_sel && is_gdt_sel(global_fs_sel)) return global_fs_sel;
 387
 388         memset( &ldt_info, 0, sizeof(ldt_info) );
 389         ldt_info.entry_number = -1;
 390         ldt_info.seg_32bit = 1;
 391         ldt_info.usable = 1;
 392         if ((ret = set_thread_area( &ldt_info ) < 0))
 393         {
 394             global_fs_sel = 0;  /* don't try it again */
 395             if (errno != ENOSYS) perror( "set_thread_area" );
 396         }
 397         else global_fs_sel = (ldt_info.entry_number << 3) | 3;
 398 #elif defined(__FreeBSD__) || defined (__FreeBSD_kernel__)
 399         global_fs_sel = GSEL( GUFS_SEL, SEL_UPL );
 400 #endif
 401     }
 402     if (global_fs_sel > 0) return global_fs_sel;
 403     return wine_ldt_alloc_entries( 1 );
 404 }
 405
 406
 407 /***********************************************************************
 408  *           wine_ldt_init_fs
 409  *
 410  * Initialize the entry for the %fs selector of the current thread, and
 411  * set the thread %fs register.
 412  *
 413  * Note: this runs in the context of the new thread, so cannot acquire locks.
 414  */
 415 void wine_ldt_init_fs( unsigned short sel, const LDT_ENTRY *entry )
 416 {
 417     if ((sel & ~3) == (global_fs_sel & ~3))
 418     {
 419 #ifdef __linux__
 420         struct modify_ldt_s ldt_info;
 421         int ret;
 422
 423         ldt_info.entry_number = sel >> 3;
 424         fill_modify_ldt_struct( &ldt_info, entry );
 425         if ((ret = set_thread_area( &ldt_info ) < 0)) perror( "set_thread_area" );
 426 #elif defined(__FreeBSD__) || defined (__FreeBSD_kernel__) || defined(__DragonFly__)
 427         i386_set_fsbase( wine_ldt_get_base( entry ));
 428 #endif
 429     }
 430     else  /* LDT selector */
 431     {
 432         internal_set_entry( sel, entry );
 433     }
 434     wine_set_fs( sel );
 435 }
 436
 437
 438 /***********************************************************************
 439  *           wine_ldt_free_fs
 440  *
 441  * Free a %fs selector returned by wine_ldt_alloc_fs.
 442  */
 443 void wine_ldt_free_fs( unsigned short sel )
 444 {
 445     if (is_gdt_sel(sel)) return;  /* nothing to do */
 446     if (!((wine_get_fs() ^ sel) & ~3))
 447     {
 448         /* FIXME: if freeing current %fs we cannot acquire locks */
 449         wine_set_fs( 0 );
 450         internal_set_entry( sel, &null_entry );
 451         wine_ldt_copy.flags[sel >> 3] = 0;
 452     }
 453     else wine_ldt_free_entries( sel, 1 );
 454 }
 455
 456
 457 /***********************************************************************
 458  *           selector access functions
 459  */
 460 __ASM_GLOBAL_FUNC( wine_get_cs, "movw %cs,%ax\n\tret" )
 461 __ASM_GLOBAL_FUNC( wine_get_ds, "movw %ds,%ax\n\tret" )
 462 __ASM_GLOBAL_FUNC( wine_get_es, "movw %es,%ax\n\tret" )
 463 __ASM_GLOBAL_FUNC( wine_get_fs, "movw %fs,%ax\n\tret" )
 464 __ASM_GLOBAL_FUNC( wine_get_gs, "movw %gs,%ax\n\tret" )
 465 __ASM_GLOBAL_FUNC( wine_get_ss, "movw %ss,%ax\n\tret" )
 466 __ASM_GLOBAL_FUNC( wine_set_fs, "movl 4(%esp),%eax\n\tmovw %ax,%fs\n\tret" )
 467 __ASM_GLOBAL_FUNC( wine_set_gs, "movl 4(%esp),%eax\n\tmovw %ax,%gs\n\tret" )
 468
 469 #endif /* __i386__ */