memory/ldt.c

   1 /*
   2  * LDT manipulation functions
   3  *
   4  * Copyright 1993 Robert J. Amstadt
   5  * Copyright 1995 Alexandre Julliard
   6  */
   7
   8 #include "config.h"
   9
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <errno.h>
  13 #include "ldt.h"
  14 #include "debugtools.h"
  15
  16 DEFAULT_DEBUG_CHANNEL(ldt)
  17
  18 #ifdef __i386__
  19
  20 #ifdef linux
  21
  22 #ifdef HAVE_SYS_SYSCALL_H
  23 # include <sys/syscall.h>
  24 #endif
  25
  26 struct modify_ldt_s
  27 {
  28     unsigned int  entry_number;
  29     unsigned long base_addr;
  30     unsigned int  limit;
  31     unsigned int  seg_32bit : 1;
  32     unsigned int  contents : 2;
  33     unsigned int  read_exec_only : 1;
  34     unsigned int  limit_in_pages : 1;
  35     unsigned int  seg_not_present : 1;
  36 };
  37
  38 static inline int modify_ldt( int func, struct modify_ldt_s *ptr,
  39                                   unsigned long count )
  40 {
  41     int res;
  42 #ifdef __PIC__
  43     __asm__ __volatile__( "pushl %%ebx\n\t"
  44                           "movl %2,%%ebx\n\t"
  45                           "int $0x80\n\t"
  46                           "popl %%ebx"
  47                           : "=a" (res)
  48                           : "0" (SYS_modify_ldt),
  49                             "r" (func),
  50                             "c" (ptr),
  51                             "d" (count) );
  52 #else
  53     __asm__ __volatile__("int $0x80"
  54                          : "=a" (res)
  55                          : "0" (SYS_modify_ldt),
  56                            "b" (func),
  57                            "c" (ptr),
  58                            "d" (count) );
  59 #endif  /* __PIC__ */
  60     if (res >= 0) return res;
  61     errno = -res;
  62     return -1;
  63 }
  64
  65 #endif  /* linux */
  66
  67 #if defined(__svr4__) || defined(_SCO_DS)
  68 #include <sys/sysi86.h>
  69 extern int sysi86(int,void*);
  70 #ifndef __sun__
  71 #include <sys/seg.h>
  72 #endif
  73 #endif
  74
  75 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
  76 #include <machine/segments.h>
  77
  78 extern int i386_get_ldt(int, union descriptor *, int);
  79 extern int i386_set_ldt(int, union descriptor *, int);
  80 #endif  /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
  81
  82 #endif  /* __i386__ */
  83
  84
  85 ldt_copy_entry ldt_copy[LDT_SIZE];
  86 unsigned char ldt_flags_copy[LDT_SIZE];
  87
  88
  89 /***********************************************************************
  90  *           LDT_BytesToEntry
  91  *
  92  * Convert the raw bytes of the descriptor to an ldt_entry structure.
  93  */
  94 void LDT_BytesToEntry( const unsigned long *buffer, ldt_entry *content )
  95 {
  96     content->base  = (*buffer >> 16) & 0x0000ffff;
  97     content->limit = *buffer & 0x0000ffff;
  98     buffer++;
  99     content->base  |= (*buffer & 0xff000000) | ((*buffer << 16) & 0x00ff0000);
 100     content->limit |= (*buffer & 0x000f0000);
 101     content->type           = (*buffer >> 10) & 3;
 102     content->seg_32bit      = (*buffer & 0x00400000) != 0;
 103     content->read_only      = (*buffer & 0x00000200) == 0;
 104     content->limit_in_pages = (*buffer & 0x00800000) != 0;
 105 }
 106
 107
 108 /***********************************************************************
 109  *           LDT_EntryToBytes
 110  *
 111  * Convert an ldt_entry structure to the raw bytes of the descriptor.
 112  */
 113 void LDT_EntryToBytes( unsigned long *buffer, const ldt_entry *content )
 114 {
 115     *buffer++ = ((content->base & 0x0000ffff) << 16) |
 116                  (content->limit & 0x0ffff);
 117     *buffer = (content->base & 0xff000000) |
 118               ((content->base & 0x00ff0000)>>16) |
 119               (content->limit & 0xf0000) |
 120               (content->type << 10) |
 121               ((content->read_only == 0) << 9) |
 122               ((content->seg_32bit != 0) << 22) |
 123               ((content->limit_in_pages != 0) << 23) |
 124               0xf000;
 125 }
 126
 127
 128 /***********************************************************************
 129  *           LDT_GetEntry
 130  *
 131  * Retrieve an LDT entry.
 132  */
 133 int LDT_GetEntry( int entry, ldt_entry *content )
 134 {
 135     int ret = 0;
 136
 137     content->base           = ldt_copy[entry].base;
 138     content->limit          = ldt_copy[entry].limit;
 139     content->type           = (ldt_flags_copy[entry] & LDT_FLAGS_TYPE);
 140     content->seg_32bit      = (ldt_flags_copy[entry] & LDT_FLAGS_32BIT) != 0;
 141     content->read_only      = (ldt_flags_copy[entry] & LDT_FLAGS_READONLY) !=0;
 142     content->limit_in_pages = (ldt_flags_copy[entry] & LDT_FLAGS_BIG) !=0;
 143     if (content->limit_in_pages) content->limit >>= 12;
 144     return ret;
 145 }
 146
 147
 148 /***********************************************************************
 149  *           LDT_SetEntry
 150  *
 151  * Set an LDT entry.
 152  */
 153 int LDT_SetEntry( int entry, const ldt_entry *content )
 154 {
 155     int ret = 0;
 156
 157     TRACE("entry=%04x base=%08lx limit=%05lx %s %d-bit "
 158                  "flags=%c%c%c\n", entry, content->base, content->limit,
 159                  content->limit_in_pages ? "pages" : "bytes",
 160                  content->seg_32bit ? 32 : 16,
 161                  content->read_only && (content->type & SEGMENT_CODE) ? '-' : 'r',
 162                  content->read_only || (content->type & SEGMENT_CODE) ? '-' : 'w',
 163                  (content->type & SEGMENT_CODE) ? 'x' : '-' );
 164
 165     /* Entry 0 must not be modified; its base and limit are always 0 */
 166     if (!entry) return 0;
 167
 168 #ifdef __i386__
 169
 170 #ifdef linux
 171     {
 172         struct modify_ldt_s ldt_info;
 173
 174         ldt_info.entry_number    = entry;
 175         ldt_info.base_addr       = content->base;
 176         ldt_info.limit           = content->limit;
 177         ldt_info.seg_32bit       = content->seg_32bit != 0;
 178         ldt_info.contents        = content->type;
 179         ldt_info.read_exec_only  = content->read_only != 0;
 180         ldt_info.limit_in_pages  = content->limit_in_pages != 0;
 181         ldt_info.seg_not_present = 0;
 182         /* Make sure the info will be accepted by the kernel */
 183         /* This is ugly, but what can I do? */
 184         if (content->type == SEGMENT_STACK)
 185         {
 186             /* FIXME */
 187         }
 188         else
 189         {
 190             if (ldt_info.base_addr >= 0xc0000000)
 191             {
 192                 WARN("Invalid base addr %08lx\n",
 193                          ldt_info.base_addr );
 194                 return -1;
 195             }
 196             if (content->limit_in_pages)
 197             {
 198                 if ((ldt_info.limit << 12) + 0xfff >
 199                                                0xc0000000 - ldt_info.base_addr)
 200                     ldt_info.limit = (0xc0000000 - 0xfff - ldt_info.base_addr) >> 12;
 201             }
 202             else
 203             {
 204                 if (ldt_info.limit > 0xc0000000 - ldt_info.base_addr)
 205                     ldt_info.limit = 0xc0000000 - ldt_info.base_addr;
 206             }
 207         }
 208         if ((ret = modify_ldt(1, &ldt_info, sizeof(ldt_info))) < 0)
 209             perror( "modify_ldt" );
 210     }
 211 #endif  /* linux */
 212
 213 #if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
 214     {
 215         long d[2];
 216
 217         LDT_EntryToBytes( d, content );
 218         ret = i386_set_ldt(entry, (union descriptor *)d, 1);
 219         if (ret < 0)
 220         {
 221             perror("i386_set_ldt");
 222             MESSAGE("Did you reconfigure the kernel with \"options USER_LDT\"?\n");
 223             exit(1);
 224         }
 225     }
 226 #endif  /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
 227
 228 #if defined(__svr4__) || defined(_SCO_DS)
 229     {
 230         struct ssd ldt_mod;
 231         int i;
 232         ldt_mod.sel = ENTRY_TO_SELECTOR(entry) | 4;
 233         ldt_mod.bo = content->base;
 234         ldt_mod.ls = content->limit;
 235         i = ((content->limit & 0xf0000) |
 236              (content->type << 10) |
 237              (((content->read_only != 0) ^ 1) << 9) |
 238              ((content->seg_32bit != 0) << 22) |
 239              ((content->limit_in_pages != 0)<< 23) |
 240              (1<<15) |
 241              0x7000);
 242
 243         ldt_mod.acc1 = (i & 0xff00) >> 8;
 244         ldt_mod.acc2 = (i & 0xf00000) >> 20;
 245
 246         if (content->base == 0)
 247         {
 248             ldt_mod.acc1 =  0;
 249             ldt_mod.acc2 = 0;
 250         }
 251         if ((ret = sysi86(SI86DSCR, &ldt_mod)) == -1) perror("sysi86");
 252     }
 253 #endif
 254
 255 #endif  /* __i386__ */
 256
 257     if (ret < 0) return ret;
 258     ldt_copy[entry].base = content->base;
 259     if (!content->limit_in_pages) ldt_copy[entry].limit = content->limit;
 260     else ldt_copy[entry].limit = (content->limit << 12) | 0x0fff;
 261     ldt_flags_copy[entry] = (content->type & LDT_FLAGS_TYPE) |
 262                             (content->read_only ? LDT_FLAGS_READONLY : 0) |
 263                             (content->seg_32bit ? LDT_FLAGS_32BIT : 0) |
 264                             (content->limit_in_pages ? LDT_FLAGS_BIG : 0) |
 265                             (ldt_flags_copy[entry] & LDT_FLAGS_ALLOCATED);
 266     return ret;
 267 }
 268
 269
 270 /***********************************************************************
 271  *           LDT_Print
 272  *
 273  * Print the content of the LDT on stdout.
 274  */
 275 void LDT_Print( int start, int length )
 276 {
 277     int i;
 278     char flags[3];
 279
 280     if (length == -1) length = LDT_SIZE - start;
 281     for (i = start; i < start + length; i++)
 282     {
 283         if (!ldt_copy[i].base && !ldt_copy[i].limit) continue; /* Free entry */
 284         if ((ldt_flags_copy[i] & LDT_FLAGS_TYPE) == SEGMENT_CODE)
 285         {
 286             flags[0] = (ldt_flags_copy[i] & LDT_FLAGS_EXECONLY) ? '-' : 'r';
 287             flags[1] = '-';
 288             flags[2] = 'x';
 289         }
 290         else
 291         {
 292             flags[0] = 'r';
 293             flags[1] = (ldt_flags_copy[i] & LDT_FLAGS_READONLY) ? '-' : 'w';
 294             flags[2] = '-';
 295         }
 296         MESSAGE("%04x: sel=%04x base=%08lx limit=%08lx %d-bit %c%c%c\n",
 297             i, ENTRY_TO_SELECTOR(i), ldt_copy[i].base, ldt_copy[i].limit,
 298             ldt_flags_copy[i] & LDT_FLAGS_32BIT ? 32 : 16,
 299             flags[0], flags[1], flags[2] );
 300     }
 301 }