boehm-gc/mark_rts.c

   1 /*
   2  * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
   3  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
   4  *
   5  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   6  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   7  *
   8  * Permission is hereby granted to use or copy this program
   9  * for any purpose,  provided the above notices are retained on all copies.
  10  * Permission to modify the code and to distribute modified code is granted,
  11  * provided the above notices are retained, and a notice that the code was
  12  * modified is included with the above copyright notice.
  13  */
  14 # include <stdio.h>
  15 # include "private/gc_priv.h"
  16
  17 /* Data structure for list of root sets.                                */
  18 /* We keep a hash table, so that we can filter out duplicate additions. */
  19 /* Under Win32, we need to do a better job of filtering overlaps, so    */
  20 /* we resort to sequential search, and pay the price.                   */
  21 /* This is really declared in gc_priv.h:
  22 struct roots {
  23         ptr_t r_start;
  24         ptr_t r_end;
  25  #      if !defined(MSWIN32) && !defined(MSWINCE)
  26           struct roots * r_next;
  27  #      endif
  28         GC_bool r_tmp;
  29                 -- Delete before registering new dynamic libraries
  30 };
  31
  32 struct roots GC_static_roots[MAX_ROOT_SETS];
  33 */
  34
  35 int GC_no_dls = 0;      /* Register dynamic library data segments.      */
  36
  37 static int n_root_sets = 0;
  38
  39         /* GC_static_roots[0..n_root_sets) contains the valid root sets. */
  40
  41 # if !defined(NO_DEBUGGING)
  42 /* For debugging:       */
  43 void GC_print_static_roots()
  44 {
  45     register int i;
  46     size_t total = 0;
  47
  48     for (i = 0; i < n_root_sets; i++) {
  49         GC_printf2("From 0x%lx to 0x%lx ",
  50                    (unsigned long) GC_static_roots[i].r_start,
  51                    (unsigned long) GC_static_roots[i].r_end);
  52         if (GC_static_roots[i].r_tmp) {
  53             GC_printf0(" (temporary)\n");
  54         } else {
  55             GC_printf0("\n");
  56         }
  57         total += GC_static_roots[i].r_end - GC_static_roots[i].r_start;
  58     }
  59     GC_printf1("Total size: %ld\n", (unsigned long) total);
  60     if (GC_root_size != total) {
  61         GC_printf1("GC_root_size incorrect: %ld!!\n",
  62                    (unsigned long) GC_root_size);
  63     }
  64 }
  65 # endif /* NO_DEBUGGING */
  66
  67 /* Primarily for debugging support:     */
  68 /* Is the address p in one of the registered static                     */
  69 /* root sections?                                                       */
  70 GC_bool GC_is_static_root(p)
  71 ptr_t p;
  72 {
  73     static int last_root_set = MAX_ROOT_SETS;
  74     register int i;
  75
  76
  77     if (last_root_set < n_root_sets
  78         && p >= GC_static_roots[last_root_set].r_start
  79         && p < GC_static_roots[last_root_set].r_end) return(TRUE);
  80     for (i = 0; i < n_root_sets; i++) {
  81         if (p >= GC_static_roots[i].r_start
  82             && p < GC_static_roots[i].r_end) {
  83             last_root_set = i;
  84             return(TRUE);
  85         }
  86     }
  87     return(FALSE);
  88 }
  89
  90 #if !defined(MSWIN32) && !defined(MSWINCE)
  91 /*
  92 #   define LOG_RT_SIZE 6
  93 #   define RT_SIZE (1 << LOG_RT_SIZE)  -- Power of 2, may be != MAX_ROOT_SETS
  94
  95     struct roots * GC_root_index[RT_SIZE];
  96         -- Hash table header.  Used only to check whether a range is
  97         -- already present.
  98         -- really defined in gc_priv.h
  99 */
 100
 101 static int rt_hash(addr)
 102 char * addr;
 103 {
 104     word result = (word) addr;
 105 #   if CPP_WORDSZ > 8*LOG_RT_SIZE
 106         result ^= result >> 8*LOG_RT_SIZE;
 107 #   endif
 108 #   if CPP_WORDSZ > 4*LOG_RT_SIZE
 109         result ^= result >> 4*LOG_RT_SIZE;
 110 #   endif
 111     result ^= result >> 2*LOG_RT_SIZE;
 112     result ^= result >> LOG_RT_SIZE;
 113     result &= (RT_SIZE-1);
 114     return(result);
 115 }
 116
 117 /* Is a range starting at b already in the table? If so return a        */
 118 /* pointer to it, else NIL.                                             */
 119 struct roots * GC_roots_present(b)
 120 char *b;
 121 {
 122     register int h = rt_hash(b);
 123     register struct roots *p = GC_root_index[h];
 124
 125     while (p != 0) {
 126         if (p -> r_start == (ptr_t)b) return(p);
 127         p = p -> r_next;
 128     }
 129     return(FALSE);
 130 }
 131
 132 /* Add the given root structure to the index. */
 133 static void add_roots_to_index(p)
 134 struct roots *p;
 135 {
 136     register int h = rt_hash(p -> r_start);
 137
 138     p -> r_next = GC_root_index[h];
 139     GC_root_index[h] = p;
 140 }
 141
 142 # else /* MSWIN32 || MSWINCE */
 143
 144 #   define add_roots_to_index(p)
 145
 146 # endif
 147
 148
 149
 150
 151 word GC_root_size = 0;
 152
 153 void GC_add_roots(b, e)
 154 char * b; char * e;
 155 {
 156     DCL_LOCK_STATE;
 157
 158     DISABLE_SIGNALS();
 159     LOCK();
 160     GC_add_roots_inner(b, e, FALSE);
 161     UNLOCK();
 162     ENABLE_SIGNALS();
 163 }
 164
 165
 166 /* Add [b,e) to the root set.  Adding the same interval a second time   */
 167 /* is a moderately fast noop, and hence benign.  We do not handle       */
 168 /* different but overlapping intervals efficiently.  (We do handle      */
 169 /* them correctly.)                                                     */
 170 /* Tmp specifies that the interval may be deleted before                */
 171 /* reregistering dynamic libraries.                                     */
 172 void GC_add_roots_inner(b, e, tmp)
 173 char * b; char * e;
 174 GC_bool tmp;
 175 {
 176     struct roots * old;
 177
 178 #   if defined(MSWIN32) || defined(MSWINCE)
 179       /* Spend the time to ensure that there are no overlapping */
 180       /* or adjacent intervals.                                 */
 181       /* This could be done faster with e.g. a                  */
 182       /* balanced tree.  But the execution time here is         */
 183       /* virtually guaranteed to be dominated by the time it    */
 184       /* takes to scan the roots.                               */
 185       {
 186         register int i;
 187
 188         for (i = 0; i < n_root_sets; i++) {
 189             old = GC_static_roots + i;
 190             if ((ptr_t)b <= old -> r_end && (ptr_t)e >= old -> r_start) {
 191                 if ((ptr_t)b < old -> r_start) {
 192                     old -> r_start = (ptr_t)b;
 193                     GC_root_size += (old -> r_start - (ptr_t)b);
 194                 }
 195                 if ((ptr_t)e > old -> r_end) {
 196                     old -> r_end = (ptr_t)e;
 197                     GC_root_size += ((ptr_t)e - old -> r_end);
 198                 }
 199                 old -> r_tmp &= tmp;
 200                 break;
 201             }
 202         }
 203         if (i < n_root_sets) {
 204           /* merge other overlapping intervals */
 205             struct roots *other;
 206
 207             for (i++; i < n_root_sets; i++) {
 208               other = GC_static_roots + i;
 209               b = (char *)(other -> r_start);
 210               e = (char *)(other -> r_end);
 211               if ((ptr_t)b <= old -> r_end && (ptr_t)e >= old -> r_start) {
 212                 if ((ptr_t)b < old -> r_start) {
 213                     old -> r_start = (ptr_t)b;
 214                     GC_root_size += (old -> r_start - (ptr_t)b);
 215                 }
 216                 if ((ptr_t)e > old -> r_end) {
 217                     old -> r_end = (ptr_t)e;
 218                     GC_root_size += ((ptr_t)e - old -> r_end);
 219                 }
 220                 old -> r_tmp &= other -> r_tmp;
 221                 /* Delete this entry. */
 222                   GC_root_size -= (other -> r_end - other -> r_start);
 223                   other -> r_start = GC_static_roots[n_root_sets-1].r_start;
 224                   other -> r_end = GC_static_roots[n_root_sets-1].r_end;
 225                                   n_root_sets--;
 226               }
 227             }
 228           return;
 229         }
 230       }
 231 #   else
 232       old = GC_roots_present(b);
 233       if (old != 0) {
 234         if ((ptr_t)e <= old -> r_end) /* already there */ return;
 235         /* else extend */
 236         GC_root_size += (ptr_t)e - old -> r_end;
 237         old -> r_end = (ptr_t)e;
 238         return;
 239       }
 240 #   endif
 241     if (n_root_sets == MAX_ROOT_SETS) {
 242         ABORT("Too many root sets\n");
 243     }
 244     GC_static_roots[n_root_sets].r_start = (ptr_t)b;
 245     GC_static_roots[n_root_sets].r_end = (ptr_t)e;
 246     GC_static_roots[n_root_sets].r_tmp = tmp;
 247 #   if !defined(MSWIN32) && !defined(MSWINCE)
 248       GC_static_roots[n_root_sets].r_next = 0;
 249 #   endif
 250     add_roots_to_index(GC_static_roots + n_root_sets);
 251     GC_root_size += (ptr_t)e - (ptr_t)b;
 252     n_root_sets++;
 253 }
 254
 255 static roots_were_cleared = FALSE;
 256
 257 void GC_clear_roots GC_PROTO((void))
 258 {
 259     DCL_LOCK_STATE;
 260
 261     DISABLE_SIGNALS();
 262     LOCK();
 263     roots_were_cleared = TRUE;
 264     n_root_sets = 0;
 265     GC_root_size = 0;
 266 #   if !defined(MSWIN32) && !defined(MSWINCE)
 267     {
 268         register int i;
 269
 270         for (i = 0; i < RT_SIZE; i++) GC_root_index[i] = 0;
 271     }
 272 #   endif
 273     UNLOCK();
 274     ENABLE_SIGNALS();
 275 }
 276
 277 /* Internal use only; lock held.        */
 278 void GC_remove_tmp_roots()
 279 {
 280     register int i;
 281
 282     for (i = 0; i < n_root_sets; ) {
 283         if (GC_static_roots[i].r_tmp) {
 284             GC_root_size -=
 285                 (GC_static_roots[i].r_end - GC_static_roots[i].r_start);
 286             GC_static_roots[i].r_start = GC_static_roots[n_root_sets-1].r_start;
 287             GC_static_roots[i].r_end = GC_static_roots[n_root_sets-1].r_end;
 288             GC_static_roots[i].r_tmp = GC_static_roots[n_root_sets-1].r_tmp;
 289             n_root_sets--;
 290         } else {
 291             i++;
 292         }
 293     }
 294 #   if !defined(MSWIN32) && !defined(MSWINCE)
 295     {
 296         register int i;
 297
 298         for (i = 0; i < RT_SIZE; i++) GC_root_index[i] = 0;
 299         for (i = 0; i < n_root_sets; i++)
 300                 add_roots_to_index(GC_static_roots + i);
 301     }
 302 #   endif
 303
 304 }
 305
 306 #if defined(MSWIN32) || defined(_WIN32_WCE_EMULATION)
 307 /* Workaround for the OS mapping and unmapping behind our back:         */
 308 /* Is the address p in one of the temporary static root sections?       */
 309 GC_bool GC_is_tmp_root(p)
 310 ptr_t p;
 311 {
 312     static int last_root_set = MAX_ROOT_SETS;
 313     register int i;
 314
 315     if (last_root_set < n_root_sets
 316         && p >= GC_static_roots[last_root_set].r_start
 317         && p < GC_static_roots[last_root_set].r_end)
 318         return GC_static_roots[last_root_set].r_tmp;
 319     for (i = 0; i < n_root_sets; i++) {
 320         if (p >= GC_static_roots[i].r_start
 321             && p < GC_static_roots[i].r_end) {
 322             last_root_set = i;
 323             return GC_static_roots[i].r_tmp;
 324         }
 325     }
 326     return(FALSE);
 327 }
 328 #endif /* MSWIN32 || _WIN32_WCE_EMULATION */
 329
 330 ptr_t GC_approx_sp()
 331 {
 332     word dummy;
 333
 334 #   ifdef _MSC_VER
 335 #     pragma warning(disable:4172)
 336 #   endif
 337     return((ptr_t)(&dummy));
 338 #   ifdef _MSC_VER
 339 #     pragma warning(default:4172)
 340 #   endif
 341 }
 342
 343 /*
 344  * Data structure for excluded static roots.
 345  * Real declaration is in gc_priv.h.
 346
 347 struct exclusion {
 348     ptr_t e_start;
 349     ptr_t e_end;
 350 };
 351
 352 struct exclusion GC_excl_table[MAX_EXCLUSIONS];
 353                                         -- Array of exclusions, ascending
 354                                         -- address order.
 355 */
 356
 357 size_t GC_excl_table_entries = 0;       /* Number of entries in use.      */
 358
 359 /* Return the first exclusion range that includes an address >= start_addr */
 360 /* Assumes the exclusion table contains at least one entry (namely the     */
 361 /* GC data structures).                                                    */
 362 struct exclusion * GC_next_exclusion(start_addr)
 363 ptr_t start_addr;
 364 {
 365     size_t low = 0;
 366     size_t high = GC_excl_table_entries - 1;
 367     size_t mid;
 368
 369     while (high > low) {
 370         mid = (low + high) >> 1;
 371         /* low <= mid < high    */
 372         if ((word) GC_excl_table[mid].e_end <= (word) start_addr) {
 373             low = mid + 1;
 374         } else {
 375             high = mid;
 376         }
 377     }
 378     if ((word) GC_excl_table[low].e_end <= (word) start_addr) return 0;
 379     return GC_excl_table + low;
 380 }
 381
 382 void GC_exclude_static_roots(start, finish)
 383 GC_PTR start;
 384 GC_PTR finish;
 385 {
 386     struct exclusion * next;
 387     size_t next_index, i;
 388
 389     if (0 == GC_excl_table_entries) {
 390         next = 0;
 391     } else {
 392         next = GC_next_exclusion(start);
 393     }
 394     if (0 != next) {
 395       if ((word)(next -> e_start) < (word) finish) {
 396         /* incomplete error check. */
 397         ABORT("exclusion ranges overlap");
 398       }
 399       if ((word)(next -> e_start) == (word) finish) {
 400         /* extend old range backwards   */
 401           next -> e_start = (ptr_t)start;
 402           return;
 403       }
 404       next_index = next - GC_excl_table;
 405       for (i = GC_excl_table_entries; i > next_index; --i) {
 406         GC_excl_table[i] = GC_excl_table[i-1];
 407       }
 408     } else {
 409       next_index = GC_excl_table_entries;
 410     }
 411     if (GC_excl_table_entries == MAX_EXCLUSIONS) ABORT("Too many exclusions");
 412     GC_excl_table[next_index].e_start = (ptr_t)start;
 413     GC_excl_table[next_index].e_end = (ptr_t)finish;
 414     ++GC_excl_table_entries;
 415 }
 416
 417 /* Invoke push_conditional on ranges that are not excluded. */
 418 void GC_push_conditional_with_exclusions(bottom, top, all)
 419 ptr_t bottom;
 420 ptr_t top;
 421 int all;
 422 {
 423     struct exclusion * next;
 424     ptr_t excl_start;
 425
 426     while (bottom < top) {
 427         next = GC_next_exclusion(bottom);
 428         if (0 == next || (excl_start = next -> e_start) >= top) {
 429             GC_push_conditional(bottom, top, all);
 430             return;
 431         }
 432         if (excl_start > bottom) GC_push_conditional(bottom, excl_start, all);
 433         bottom = next -> e_end;
 434     }
 435 }
 436
 437 /*
 438  * In the absence of threads, push the stack contents.
 439  * In the presence of threads, push enough of the current stack
 440  * to ensure that callee-save registers saved in collector frames have been
 441  * seen.
 442  */
 443 void GC_push_current_stack(cold_gc_frame)
 444 ptr_t cold_gc_frame;
 445 {
 446 #   if defined(THREADS)
 447         if (0 == cold_gc_frame) return;
 448 #       ifdef STACK_GROWS_DOWN
 449           GC_push_all_eager(GC_approx_sp(), cold_gc_frame);
 450           /* For IA64, the register stack backing store is handled      */
 451           /* in the thread-specific code.                               */
 452 #       else
 453           GC_push_all_eager( cold_gc_frame, GC_approx_sp() );
 454 #       endif
 455 #   else
 456 #       ifdef STACK_GROWS_DOWN
 457             GC_push_all_stack_partially_eager( GC_approx_sp(), GC_stackbottom,
 458                                                cold_gc_frame );
 459 #           ifdef IA64
 460               /* We also need to push the register stack backing store. */
 461               /* This should really be done in the same way as the      */
 462               /* regular stack.  For now we fudge it a bit.             */
 463               /* Note that the backing store grows up, so we can't use  */
 464               /* GC_push_all_stack_partially_eager.                     */
 465               {
 466                 extern word GC_save_regs_ret_val;
 467                         /* Previously set to backing store pointer.     */
 468                 ptr_t bsp = (ptr_t) GC_save_regs_ret_val;
 469                 ptr_t cold_gc_bs_pointer;
 470                 if (GC_all_interior_pointers) {
 471                   cold_gc_bs_pointer = bsp - 2048;
 472                   if (cold_gc_bs_pointer < BACKING_STORE_BASE) {
 473                     cold_gc_bs_pointer = BACKING_STORE_BASE;
 474                   } else {
 475                     GC_push_all_stack(BACKING_STORE_BASE, cold_gc_bs_pointer);
 476                   }
 477                 } else {
 478                   cold_gc_bs_pointer = BACKING_STORE_BASE;
 479                 }
 480                 GC_push_all_eager(cold_gc_bs_pointer, bsp);
 481                 /* All values should be sufficiently aligned that we    */
 482                 /* dont have to worry about the boundary.               */
 483               }
 484 #           endif
 485 #       else
 486             GC_push_all_stack_partially_eager( GC_stackbottom, GC_approx_sp(),
 487                                                cold_gc_frame );
 488 #       endif
 489 #   endif /* !THREADS */
 490 }
 491
 492 /*
 493  * Push GC internal roots.  Only called if there is some reason to believe
 494  * these would not otherwise get registered.
 495  */
 496 void GC_push_gc_structures GC_PROTO((void))
 497 {
 498     GC_push_finalizer_structures();
 499     GC_push_stubborn_structures();
 500 #   if defined(THREADS)
 501       GC_push_thread_structures();
 502 #   endif
 503 }
 504
 505 #ifdef THREAD_LOCAL_ALLOC
 506   void GC_mark_thread_local_free_lists();
 507 #endif
 508
 509 /*
 510  * Call the mark routines (GC_tl_push for a single pointer, GC_push_conditional
 511  * on groups of pointers) on every top level accessible pointer.
 512  * If all is FALSE, arrange to push only possibly altered values.
 513  * Cold_gc_frame is an address inside a GC frame that
 514  * remains valid until all marking is complete.
 515  * A zero value indicates that it's OK to miss some
 516  * register values.
 517  */
 518 void GC_push_roots(all, cold_gc_frame)
 519 GC_bool all;
 520 ptr_t cold_gc_frame;
 521 {
 522     register int i;
 523
 524     /*
 525      * push registers - i.e., call GC_push_one(r) for each
 526      * register contents r.
 527      */
 528 #   ifdef USE_GENERIC_PUSH_REGS
 529         GC_generic_push_regs(cold_gc_frame);
 530 #   else
 531         GC_push_regs(); /* usually defined in machine_dep.c */
 532 #   endif
 533
 534     /*
 535      * Next push static data.  This must happen early on, since it's
 536      * not robust against mark stack overflow.
 537      */
 538      /* Reregister dynamic libraries, in case one got added.    */
 539 #      if (defined(DYNAMIC_LOADING) || defined(MSWIN32) || defined(MSWINCE) \
 540            || defined(PCR)) && !defined(SRC_M3)
 541          GC_remove_tmp_roots();
 542          if (!GC_no_dls) GC_register_dynamic_libraries();
 543 #      else
 544          GC_no_dls = TRUE;
 545 #      endif
 546
 547      /* Mark everything in static data areas                             */
 548        for (i = 0; i < n_root_sets; i++) {
 549          GC_push_conditional_with_exclusions(
 550                              GC_static_roots[i].r_start,
 551                              GC_static_roots[i].r_end, all);
 552        }
 553
 554      /* Mark from GC internal roots if those might otherwise have       */
 555      /* been excluded.                                                  */
 556        if (GC_no_dls || roots_were_cleared) {
 557            GC_push_gc_structures();
 558        }
 559
 560      /* Mark thread local free lists, even if their mark        */
 561      /* descriptor excludes the link field.                     */
 562 #      ifdef THREAD_LOCAL_ALLOC
 563          GC_mark_thread_local_free_lists();
 564 #      endif
 565
 566     /*
 567      * Now traverse stacks.
 568      */
 569 #   if !defined(USE_GENERIC_PUSH_REGS)
 570         GC_push_current_stack(cold_gc_frame);
 571         /* In the threads case, this only pushes collector frames.      */
 572         /* In the USE_GENERIC_PUSH_REGS case, this is done inside       */
 573         /* GC_push_regs, so that we catch callee-save registers saved   */
 574         /* inside the GC_push_regs frame.                               */
 575         /* In the case of linux threads on IA64, the hot section of     */
 576         /* the main stack is marked here, but the register stack        */
 577         /* backing store is handled in the threads-specific code.       */
 578 #   endif
 579     if (GC_push_other_roots != 0) (*GC_push_other_roots)();
 580         /* In the threads case, this also pushes thread stacks. */
 581 }
 582