gdb/addrmap.c

   1 /* addrmap.c --- implementation of address map data structure.
   2
   3    Copyright (C) 2007-2024 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program 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
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "gdbsupport/gdb_obstack.h"
  22 #include "addrmap.h"
  23 #include "gdbsupport/selftest.h"
  24
  25 /* Make sure splay trees can actually hold the values we want to
  26    store in them.  */
  27 static_assert (sizeof (splay_tree_key) >= sizeof (CORE_ADDR *));
  28 static_assert (sizeof (splay_tree_value) >= sizeof (void *));
  29
  30 \f
  31 /* Fixed address maps.  */
  32
  33 void *
  34 addrmap_fixed::do_find (CORE_ADDR addr) const
  35 {
  36   const struct addrmap_transition *bottom = &transitions[0];
  37   const struct addrmap_transition *top = &transitions[num_transitions - 1];
  38
  39   while (bottom < top)
  40     {
  41       /* This needs to round towards top, or else when top = bottom +
  42          1 (i.e., two entries are under consideration), then mid ==
  43          bottom, and then we may not narrow the range when (mid->addr
  44          < addr).  */
  45       const addrmap_transition *mid = top - (top - bottom) / 2;
  46
  47       if (mid->addr == addr)
  48         {
  49           bottom = mid;
  50           break;
  51         }
  52       else if (mid->addr < addr)
  53         /* We don't eliminate mid itself here, since each transition
  54            covers all subsequent addresses until the next.  This is why
  55            we must round up in computing the midpoint.  */
  56         bottom = mid;
  57       else
  58         top = mid - 1;
  59     }
  60
  61   return bottom->value;
  62 }
  63
  64
  65 void
  66 addrmap_fixed::relocate (CORE_ADDR offset)
  67 {
  68   size_t i;
  69
  70   for (i = 0; i < num_transitions; i++)
  71     transitions[i].addr += offset;
  72 }
  73
  74
  75 int
  76 addrmap_fixed::do_foreach (addrmap_foreach_fn fn) const
  77 {
  78   size_t i;
  79
  80   for (i = 0; i < num_transitions; i++)
  81     {
  82       int res = fn (transitions[i].addr, transitions[i].value);
  83
  84       if (res != 0)
  85         return res;
  86     }
  87
  88   return 0;
  89 }
  90
  91
  92 \f
  93 /* Mutable address maps.  */
  94
  95 /* Allocate a copy of CORE_ADDR.  */
  96 splay_tree_key
  97 addrmap_mutable::allocate_key (CORE_ADDR addr)
  98 {
  99   CORE_ADDR *key = XNEW (CORE_ADDR);
 100
 101   *key = addr;
 102   return (splay_tree_key) key;
 103 }
 104
 105
 106 /* Type-correct wrappers for splay tree access.  */
 107 splay_tree_node
 108 addrmap_mutable::splay_tree_lookup (CORE_ADDR addr) const
 109 {
 110   return ::splay_tree_lookup (tree, (splay_tree_key) &addr);
 111 }
 112
 113
 114 splay_tree_node
 115 addrmap_mutable::splay_tree_predecessor (CORE_ADDR addr) const
 116 {
 117   return ::splay_tree_predecessor (tree, (splay_tree_key) &addr);
 118 }
 119
 120
 121 splay_tree_node
 122 addrmap_mutable::splay_tree_successor (CORE_ADDR addr)
 123 {
 124   return ::splay_tree_successor (tree, (splay_tree_key) &addr);
 125 }
 126
 127
 128 void
 129 addrmap_mutable::splay_tree_remove (CORE_ADDR addr)
 130 {
 131   ::splay_tree_remove (tree, (splay_tree_key) &addr);
 132 }
 133
 134
 135 static CORE_ADDR
 136 addrmap_node_key (splay_tree_node node)
 137 {
 138   return * (CORE_ADDR *) node->key;
 139 }
 140
 141
 142 static void *
 143 addrmap_node_value (splay_tree_node node)
 144 {
 145   return (void *) node->value;
 146 }
 147
 148
 149 static void
 150 addrmap_node_set_value (splay_tree_node node, void *value)
 151 {
 152   node->value = (splay_tree_value) value;
 153 }
 154
 155
 156 void
 157 addrmap_mutable::splay_tree_insert (CORE_ADDR key, void *value)
 158 {
 159   ::splay_tree_insert (tree,
 160                        allocate_key (key),
 161                        (splay_tree_value) value);
 162 }
 163
 164
 165 /* Without changing the mapping of any address, ensure that there is a
 166    tree node at ADDR, even if it would represent a "transition" from
 167    one value to the same value.  */
 168 void
 169 addrmap_mutable::force_transition (CORE_ADDR addr)
 170 {
 171   splay_tree_node n = splay_tree_lookup (addr);
 172
 173   if (! n)
 174     {
 175       n = splay_tree_predecessor (addr);
 176       splay_tree_insert (addr, n ? addrmap_node_value (n) : NULL);
 177     }
 178 }
 179
 180
 181 void
 182 addrmap_mutable::set_empty (CORE_ADDR start, CORE_ADDR end_inclusive,
 183                             void *obj)
 184 {
 185   splay_tree_node n, next;
 186   void *prior_value;
 187
 188   /* If we're being asked to set all empty portions of the given
 189      address range to empty, then probably the caller is confused.
 190      (If that turns out to be useful in some cases, then we can change
 191      this to simply return, since overriding NULL with NULL is a
 192      no-op.)  */
 193   gdb_assert (obj);
 194
 195   /* We take a two-pass approach, for simplicity.
 196      - Establish transitions where we think we might need them.
 197      - First pass: change all NULL regions to OBJ.
 198      - Second pass: remove any unnecessary transitions.  */
 199
 200   /* Establish transitions at the start and end.  */
 201   force_transition (start);
 202   if (end_inclusive < CORE_ADDR_MAX)
 203     force_transition (end_inclusive + 1);
 204
 205   /* Walk the area, changing all NULL regions to OBJ.  */
 206   for (n = splay_tree_lookup (start), gdb_assert (n);
 207        n && addrmap_node_key (n) <= end_inclusive;
 208        n = splay_tree_successor (addrmap_node_key (n)))
 209     {
 210       if (! addrmap_node_value (n))
 211         addrmap_node_set_value (n, obj);
 212     }
 213
 214   /* Walk the area again, removing transitions from any value to
 215      itself.  Be sure to visit both the transitions we forced
 216      above.  */
 217   n = splay_tree_predecessor (start);
 218   prior_value = n ? addrmap_node_value (n) : NULL;
 219   for (n = splay_tree_lookup (start), gdb_assert (n);
 220        n && (end_inclusive == CORE_ADDR_MAX
 221              || addrmap_node_key (n) <= end_inclusive + 1);
 222        n = next)
 223     {
 224       next = splay_tree_successor (addrmap_node_key (n));
 225       if (addrmap_node_value (n) == prior_value)
 226         splay_tree_remove (addrmap_node_key (n));
 227       else
 228         prior_value = addrmap_node_value (n);
 229     }
 230 }
 231
 232
 233 void *
 234 addrmap_mutable::do_find (CORE_ADDR addr) const
 235 {
 236   splay_tree_node n = splay_tree_lookup (addr);
 237   if (n != nullptr)
 238     {
 239       gdb_assert (addrmap_node_key (n) == addr);
 240       return addrmap_node_value (n);
 241     }
 242
 243   n = splay_tree_predecessor (addr);
 244   if (n != nullptr)
 245     {
 246       gdb_assert (addrmap_node_key (n) < addr);
 247       return addrmap_node_value (n);
 248     }
 249
 250   return nullptr;
 251 }
 252
 253
 254 addrmap_fixed::addrmap_fixed (struct obstack *obstack, addrmap_mutable *mut)
 255 {
 256   size_t transition_count = 0;
 257
 258   /* Count the number of transitions in the tree.  */
 259   mut->foreach ([&] (CORE_ADDR start, void *obj)
 260     {
 261       ++transition_count;
 262       return 0;
 263     });
 264
 265   /* Include an extra entry for the transition at zero (which fixed
 266      maps have, but mutable maps do not.)  */
 267   transition_count++;
 268
 269   num_transitions = 1;
 270   transitions = XOBNEWVEC (obstack, struct addrmap_transition,
 271                            transition_count);
 272   transitions[0].addr = 0;
 273   transitions[0].value = NULL;
 274
 275   /* Copy all entries from the splay tree to the array, in order
 276      of increasing address.  */
 277   mut->foreach ([&] (CORE_ADDR start, void *obj)
 278     {
 279       transitions[num_transitions].addr = start;
 280       transitions[num_transitions].value = obj;
 281       ++num_transitions;
 282       return 0;
 283     });
 284
 285   /* We should have filled the array.  */
 286   gdb_assert (num_transitions == transition_count);
 287 }
 288
 289
 290 void
 291 addrmap_mutable::relocate (CORE_ADDR offset)
 292 {
 293   /* Not needed yet.  */
 294   internal_error (_("addrmap_relocate is not implemented yet "
 295                     "for mutable addrmaps"));
 296 }
 297
 298
 299 /* This is a splay_tree_foreach_fn.  */
 300
 301 static int
 302 addrmap_mutable_foreach_worker (splay_tree_node node, void *data)
 303 {
 304   addrmap_foreach_fn *fn = (addrmap_foreach_fn *) data;
 305
 306   return (*fn) (addrmap_node_key (node), addrmap_node_value (node));
 307 }
 308
 309
 310 int
 311 addrmap_mutable::do_foreach (addrmap_foreach_fn fn) const
 312 {
 313   return splay_tree_foreach (tree, addrmap_mutable_foreach_worker, &fn);
 314 }
 315
 316
 317 /* Compare keys as CORE_ADDR * values.  */
 318 static int
 319 splay_compare_CORE_ADDR_ptr (splay_tree_key ak, splay_tree_key bk)
 320 {
 321   CORE_ADDR a = * (CORE_ADDR *) ak;
 322   CORE_ADDR b = * (CORE_ADDR *) bk;
 323
 324   /* We can't just return a-b here, because of over/underflow.  */
 325   if (a < b)
 326     return -1;
 327   else if (a == b)
 328     return 0;
 329   else
 330     return 1;
 331 }
 332
 333
 334 static void
 335 xfree_wrapper (splay_tree_key key)
 336 {
 337   xfree ((void *) key);
 338 }
 339
 340 addrmap_mutable::addrmap_mutable ()
 341   : tree (splay_tree_new (splay_compare_CORE_ADDR_ptr, xfree_wrapper,
 342                           nullptr /* no delete value */))
 343 {
 344 }
 345
 346 addrmap_mutable::~addrmap_mutable ()
 347 {
 348   splay_tree_delete (tree);
 349 }
 350
 351
 352 /* See addrmap.h.  */
 353
 354 void
 355 addrmap_dump (struct addrmap *map, struct ui_file *outfile, void *payload)
 356 {
 357   /* True if the previously printed addrmap entry was for PAYLOAD.
 358      If so, we want to print the next one as well (since the next
 359      addrmap entry defines the end of the range).  */
 360   bool previous_matched = false;
 361
 362   auto callback = [&] (CORE_ADDR start_addr, const void *obj)
 363   {
 364     QUIT;
 365
 366     bool matches = payload == nullptr || payload == obj;
 367     const char *addr_str = nullptr;
 368     if (matches)
 369       addr_str = host_address_to_string (obj);
 370     else if (previous_matched)
 371       addr_str = "<ends here>";
 372
 373     if (matches || previous_matched)
 374       gdb_printf (outfile, "  %s%s %s\n",
 375                   payload != nullptr ? "  " : "",
 376                   core_addr_to_string (start_addr),
 377                   addr_str);
 378
 379     previous_matched = matches;
 380
 381     return 0;
 382   };
 383
 384   map->foreach (callback);
 385 }
 386
 387 #if GDB_SELF_TEST
 388 namespace selftests {
 389
 390 /* Convert P to CORE_ADDR.  */
 391
 392 static CORE_ADDR
 393 core_addr (void *p)
 394 {
 395   return (CORE_ADDR)(uintptr_t)p;
 396 }
 397
 398 /* Check that &ARRAY[LOW]..&ARRAY[HIGH] has VAL in MAP.  */
 399
 400 #define CHECK_ADDRMAP_FIND(MAP, ARRAY, LOW, HIGH, VAL)                  \
 401   do                                                                    \
 402     {                                                                   \
 403       for (unsigned i = LOW; i <= HIGH; ++i)                            \
 404         SELF_CHECK (MAP->find (core_addr (&ARRAY[i])) == VAL);          \
 405     }                                                                   \
 406   while (0)
 407
 408 /* Entry point for addrmap unit tests.  */
 409
 410 static void
 411 test_addrmap ()
 412 {
 413   /* We'll verify using the addresses of the elements of this array.  */
 414   char array[20];
 415
 416   /* We'll verify using these values stored into the map.  */
 417   void *val1 = &array[1];
 418   void *val2 = &array[2];
 419
 420   /* Create mutable addrmap.  */
 421   auto_obstack temp_obstack;
 422   auto map = std::make_unique<struct addrmap_mutable> ();
 423   SELF_CHECK (map != nullptr);
 424
 425   /* Check initial state.  */
 426   CHECK_ADDRMAP_FIND (map, array, 0, 19, nullptr);
 427
 428   /* Insert address range into mutable addrmap.  */
 429   map->set_empty (core_addr (&array[10]), core_addr (&array[12]), val1);
 430   CHECK_ADDRMAP_FIND (map, array, 0, 9, nullptr);
 431   CHECK_ADDRMAP_FIND (map, array, 10, 12, val1);
 432   CHECK_ADDRMAP_FIND (map, array, 13, 19, nullptr);
 433
 434   /* Create corresponding fixed addrmap.  */
 435   struct addrmap *map2
 436     = new (&temp_obstack) addrmap_fixed (&temp_obstack, map.get ());
 437   SELF_CHECK (map2 != nullptr);
 438   CHECK_ADDRMAP_FIND (map2, array, 0, 9, nullptr);
 439   CHECK_ADDRMAP_FIND (map2, array, 10, 12, val1);
 440   CHECK_ADDRMAP_FIND (map2, array, 13, 19, nullptr);
 441
 442   /* Iterate over both addrmaps.  */
 443   auto callback = [&] (CORE_ADDR start_addr, void *obj)
 444     {
 445       if (start_addr == core_addr (nullptr))
 446         SELF_CHECK (obj == nullptr);
 447       else if (start_addr == core_addr (&array[10]))
 448         SELF_CHECK (obj == val1);
 449       else if (start_addr == core_addr (&array[13]))
 450         SELF_CHECK (obj == nullptr);
 451       else
 452         SELF_CHECK (false);
 453       return 0;
 454     };
 455   SELF_CHECK (map->foreach (callback) == 0);
 456   SELF_CHECK (map2->foreach (callback) == 0);
 457
 458   /* Relocate fixed addrmap.  */
 459   map2->relocate (1);
 460   CHECK_ADDRMAP_FIND (map2, array, 0, 10, nullptr);
 461   CHECK_ADDRMAP_FIND (map2, array, 11, 13, val1);
 462   CHECK_ADDRMAP_FIND (map2, array, 14, 19, nullptr);
 463
 464   /* Insert partially overlapping address range into mutable addrmap.  */
 465   map->set_empty (core_addr (&array[11]), core_addr (&array[13]), val2);
 466   CHECK_ADDRMAP_FIND (map, array, 0, 9, nullptr);
 467   CHECK_ADDRMAP_FIND (map, array, 10, 12, val1);
 468   CHECK_ADDRMAP_FIND (map, array, 13, 13, val2);
 469   CHECK_ADDRMAP_FIND (map, array, 14, 19, nullptr);
 470 }
 471
 472 } // namespace selftests
 473 #endif /* GDB_SELF_TEST */
 474
 475 void _initialize_addrmap ();
 476 void
 477 _initialize_addrmap ()
 478 {
 479 #if GDB_SELF_TEST
 480   selftests::register_test ("addrmap", selftests::test_addrmap);
 481 #endif /* GDB_SELF_TEST */
 482 }