1 /*
   2  * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "logging/log.hpp"
  27 #include "memory/resourceArea.hpp"
  28 #include "memory/virtualspace.hpp"
  29 #include "oops/compressedOops.hpp"
  30 #include "oops/markWord.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "runtime/globals_extension.hpp"
  33 #include "runtime/java.hpp"
  34 #include "runtime/os.hpp"
  35 #include "services/memTracker.hpp"
  36 #include "utilities/align.hpp"
  37 #include "utilities/formatBuffer.hpp"
  38 #include "utilities/powerOfTwo.hpp"
  39 
  40 // ReservedSpace
  41 
  42 // Dummy constructor
  43 ReservedSpace::ReservedSpace() : _base(NULL), _size(0), _noaccess_prefix(0),
  44     _alignment(0), _special(false), _fd_for_heap(-1), _executable(false) {
  45 }
  46 
  47 ReservedSpace::ReservedSpace(size_t size) : _fd_for_heap(-1) {
  48   // Want to use large pages where possible. If the size is
  49   // not large page aligned the mapping will be a mix of
  50   // large and normal pages.
  51   size_t page_size = os::page_size_for_region_unaligned(size, 1);
  52   size_t alignment = os::vm_allocation_granularity();
  53   initialize(size, alignment, page_size, NULL, false);
  54 }
  55 
  56 ReservedSpace::ReservedSpace(size_t size, size_t preferred_page_size) : _fd_for_heap(-1) {
  57   // When a page size is given we don't want to mix large
  58   // and normal pages. If the size is not a multiple of the
  59   // page size it will be aligned up to achieve this.
  60   size_t alignment = os::vm_allocation_granularity();;
  61   if (preferred_page_size != (size_t)os::vm_page_size()) {
  62     alignment = MAX2(preferred_page_size, alignment);
  63     size = align_up(size, alignment);
  64   }
  65   initialize(size, alignment, preferred_page_size, NULL, false);
  66 }
  67 
  68 ReservedSpace::ReservedSpace(size_t size,
  69                              size_t alignment,
  70                              size_t page_size,
  71                              char* requested_address) : _fd_for_heap(-1) {
  72   initialize(size, alignment, page_size, requested_address, false);
  73 }
  74 
  75 ReservedSpace::ReservedSpace(char* base, size_t size, size_t alignment, size_t page_size,
  76                              bool special, bool executable) : _fd_for_heap(-1) {
  77   assert((size % os::vm_allocation_granularity()) == 0,
  78          "size not allocation aligned");
  79   initialize_members(base, size, alignment, page_size, special, executable);
  80 }
  81 
  82 // Helper method
  83 static char* attempt_map_or_reserve_memory_at(char* base, size_t size, int fd, bool executable) {
  84   if (fd != -1) {
  85     return os::attempt_map_memory_to_file_at(base, size, fd);
  86   }
  87   return os::attempt_reserve_memory_at(base, size, executable);
  88 }
  89 
  90 // Helper method
  91 static char* map_or_reserve_memory(size_t size, int fd, bool executable) {
  92   if (fd != -1) {
  93     return os::map_memory_to_file(size, fd);
  94   }
  95   return os::reserve_memory(size, executable);
  96 }
  97 
  98 // Helper method
  99 static char* map_or_reserve_memory_aligned(size_t size, size_t alignment, int fd, bool executable) {
 100   if (fd != -1) {
 101     return os::map_memory_to_file_aligned(size, alignment, fd);
 102   }
 103   return os::reserve_memory_aligned(size, alignment, executable);
 104 }
 105 
 106 // Helper method
 107 static void unmap_or_release_memory(char* base, size_t size, bool is_file_mapped) {
 108   if (is_file_mapped) {
 109     if (!os::unmap_memory(base, size)) {
 110       fatal("os::unmap_memory failed");
 111     }
 112   } else if (!os::release_memory(base, size)) {
 113     fatal("os::release_memory failed");
 114   }
 115 }
 116 
 117 // Helper method
 118 static bool failed_to_reserve_as_requested(char* base, char* requested_address) {
 119   if (base == requested_address || requested_address == NULL) {
 120     return false; // did not fail
 121   }
 122 
 123   if (base != NULL) {
 124     // Different reserve address may be acceptable in other cases
 125     // but for compressed oops heap should be at requested address.
 126     assert(UseCompressedOops, "currently requested address used only for compressed oops");
 127     log_debug(gc, heap, coops)("Reserved memory not at requested address: " PTR_FORMAT " vs " PTR_FORMAT, p2i(base), p2i(requested_address));
 128   }
 129   return true;
 130 }
 131 
 132 static bool use_explicit_large_pages(size_t page_size) {
 133   return !os::can_commit_large_page_memory() &&
 134          page_size != (size_t) os::vm_page_size();
 135 }
 136 
 137 static bool large_pages_requested() {
 138   return UseLargePages &&
 139          (!FLAG_IS_DEFAULT(UseLargePages) || !FLAG_IS_DEFAULT(LargePageSizeInBytes));
 140 }
 141 
 142 static void log_on_large_pages_failure(char* req_addr, size_t bytes) {
 143   if (large_pages_requested()) {
 144     // Compressed oops logging.
 145     log_debug(gc, heap, coops)("Reserve regular memory without large pages");
 146     // JVM style warning that we did not succeed in using large pages.
 147     char msg[128];
 148     jio_snprintf(msg, sizeof(msg), "Failed to reserve and commit memory using large pages. "
 149                                    "req_addr: " PTR_FORMAT " bytes: " SIZE_FORMAT,
 150                                    req_addr, bytes);
 151     warning("%s", msg);
 152   }
 153 }
 154 
 155 static char* reserve_memory(char* requested_address, const size_t size,
 156                             const size_t alignment, int fd, bool exec) {
 157   char* base;
 158   // If the memory was requested at a particular address, use
 159   // os::attempt_reserve_memory_at() to avoid mapping over something
 160   // important.  If the reservation fails, return NULL.
 161   if (requested_address != 0) {
 162     assert(is_aligned(requested_address, alignment),
 163            "Requested address " PTR_FORMAT " must be aligned to " SIZE_FORMAT,
 164            p2i(requested_address), alignment);
 165     base = attempt_map_or_reserve_memory_at(requested_address, size, fd, exec);
 166   } else {
 167     // Optimistically assume that the OS returns an aligned base pointer.
 168     // When reserving a large address range, most OSes seem to align to at
 169     // least 64K.
 170     base = map_or_reserve_memory(size, fd, exec);
 171     // Check alignment constraints. This is only needed when there is
 172     // no requested address.
 173     if (!is_aligned(base, alignment)) {
 174       // Base not aligned, retry.
 175       unmap_or_release_memory(base, size, fd != -1 /*is_file_mapped*/);
 176       // Map using the requested alignment.
 177       base = map_or_reserve_memory_aligned(size, alignment, fd, exec);
 178     }
 179   }
 180 
 181   return base;
 182 }
 183 
 184 static char* reserve_memory_special(char* requested_address, const size_t size,
 185                                     const size_t alignment, const size_t page_size, bool exec) {
 186 
 187   log_trace(pagesize)("Attempt special mapping: size: " SIZE_FORMAT "%s, "
 188                       "alignment: " SIZE_FORMAT "%s",
 189                       byte_size_in_exact_unit(size), exact_unit_for_byte_size(size),
 190                       byte_size_in_exact_unit(alignment), exact_unit_for_byte_size(alignment));
 191 
 192   char* base = os::reserve_memory_special(size, alignment, page_size, requested_address, exec);
 193   if (base != NULL) {
 194     // Check alignment constraints.
 195     assert(is_aligned(base, alignment),
 196            "reserve_memory_special() returned an unaligned address, base: " PTR_FORMAT
 197            " alignment: " SIZE_FORMAT_HEX,
 198            p2i(base), alignment);
 199   }
 200   return base;
 201 }
 202 
 203 void ReservedSpace::clear_members() {
 204   initialize_members(NULL, 0, 0, 0, false, false);
 205 }
 206 
 207 void ReservedSpace::initialize_members(char* base, size_t size, size_t alignment,
 208                                        size_t page_size, bool special, bool executable) {
 209   _base = base;
 210   _size = size;
 211   _alignment = alignment;
 212   _page_size = page_size;
 213   _special = special;
 214   _executable = executable;
 215   _noaccess_prefix = 0;
 216 }
 217 
 218 void ReservedSpace::reserve(size_t size,
 219                             size_t alignment,
 220                             size_t page_size,
 221                             char* requested_address,
 222                             bool executable) {
 223   assert(is_aligned(size, alignment), "Size must be aligned to the requested alignment");
 224 
 225   // There are basically three different cases that we need to handle below:
 226   // - Mapping backed by a file
 227   // - Mapping backed by explicit large pages
 228   // - Mapping backed by normal pages or transparent huge pages
 229   // The first two have restrictions that requires the whole mapping to be
 230   // committed up front. To record this the ReservedSpace is marked 'special'.
 231 
 232   if (_fd_for_heap != -1) {
 233     // When there is a backing file directory for this space then whether
 234     // large pages are allocated is up to the filesystem of the backing file.
 235     // So UseLargePages is not taken into account for this reservation.
 236     char* base = reserve_memory(requested_address, size, alignment, _fd_for_heap, executable);
 237     if (base != NULL) {
 238       initialize_members(base, size, alignment, os::vm_page_size(), true, executable);
 239     }
 240     // Always return, not possible to fall back to reservation not using a file.
 241     return;
 242   } else if (use_explicit_large_pages(page_size)) {
 243     // System can't commit large pages i.e. use transparent huge pages and
 244     // the caller requested large pages. To satisfy this request we use
 245     // explicit large pages and these have to be committed up front to ensure
 246     // no reservations are lost.
 247     size_t used_page_size = page_size;
 248     char* base = NULL;
 249 
 250     do {
 251       base = reserve_memory_special(requested_address, size, alignment, used_page_size, executable);
 252       if (base != NULL) {
 253         break;
 254       }
 255       used_page_size = os::page_sizes().next_smaller(used_page_size);
 256     } while (used_page_size > (size_t) os::vm_page_size());
 257 
 258     if (base != NULL) {
 259       // Successful reservation using large pages.
 260       initialize_members(base, size, alignment, used_page_size, true, executable);
 261       return;
 262     }
 263     // Failed to reserve explicit large pages, do proper logging.
 264     log_on_large_pages_failure(requested_address, size);
 265     // Now fall back to normal reservation.
 266     page_size = os::vm_page_size();
 267   }
 268 
 269   // Not a 'special' reservation.
 270   char* base = reserve_memory(requested_address, size, alignment, -1, executable);
 271   if (base != NULL) {
 272     // Successful mapping.
 273     initialize_members(base, size, alignment, page_size, false, executable);
 274   }
 275 }
 276 
 277 void ReservedSpace::initialize(size_t size,
 278                                size_t alignment,
 279                                size_t page_size,
 280                                char* requested_address,
 281                                bool executable) {
 282   const size_t granularity = os::vm_allocation_granularity();
 283   assert((size & (granularity - 1)) == 0,
 284          "size not aligned to os::vm_allocation_granularity()");
 285   assert((alignment & (granularity - 1)) == 0,
 286          "alignment not aligned to os::vm_allocation_granularity()");
 287   assert(alignment == 0 || is_power_of_2((intptr_t)alignment),
 288          "not a power of 2");
 289   assert(page_size >= (size_t) os::vm_page_size(), "Invalid page size");
 290   assert(is_power_of_2(page_size), "Invalid page size");
 291 
 292   clear_members();
 293 
 294   if (size == 0) {
 295     return;
 296   }
 297 
 298   // Adjust alignment to not be 0.
 299   alignment = MAX2(alignment, (size_t)os::vm_page_size());
 300 
 301   // Reserve the memory.
 302   reserve(size, alignment, page_size, requested_address, executable);
 303 
 304   // Check that the requested address is used if given.
 305   if (failed_to_reserve_as_requested(_base, requested_address)) {
 306     // OS ignored the requested address, release the reservation.
 307     release();
 308     return;
 309   }
 310 }
 311 
 312 ReservedSpace ReservedSpace::first_part(size_t partition_size, size_t alignment) {
 313   assert(partition_size <= size(), "partition failed");
 314   ReservedSpace result(base(), partition_size, alignment, page_size(), special(), executable());
 315   return result;
 316 }
 317 
 318 
 319 ReservedSpace
 320 ReservedSpace::last_part(size_t partition_size, size_t alignment) {
 321   assert(partition_size <= size(), "partition failed");
 322   ReservedSpace result(base() + partition_size, size() - partition_size,
 323                        alignment, page_size(), special(), executable());
 324   return result;
 325 }
 326 
 327 
 328 size_t ReservedSpace::page_align_size_up(size_t size) {
 329   return align_up(size, os::vm_page_size());
 330 }
 331 
 332 
 333 size_t ReservedSpace::page_align_size_down(size_t size) {
 334   return align_down(size, os::vm_page_size());
 335 }
 336 
 337 
 338 size_t ReservedSpace::allocation_align_size_up(size_t size) {
 339   return align_up(size, os::vm_allocation_granularity());
 340 }
 341 
 342 void ReservedSpace::release() {
 343   if (is_reserved()) {
 344     char *real_base = _base - _noaccess_prefix;
 345     const size_t real_size = _size + _noaccess_prefix;
 346     if (special()) {
 347       if (_fd_for_heap != -1) {
 348         os::unmap_memory(real_base, real_size);
 349       } else {
 350         os::release_memory_special(real_base, real_size);
 351       }
 352     } else{
 353       os::release_memory(real_base, real_size);
 354     }
 355     clear_members();
 356   }
 357 }
 358 
 359 static size_t noaccess_prefix_size(size_t alignment) {
 360   return lcm(os::vm_page_size(), alignment);
 361 }
 362 
 363 void ReservedHeapSpace::establish_noaccess_prefix() {
 364   assert(_alignment >= (size_t)os::vm_page_size(), "must be at least page size big");
 365   _noaccess_prefix = noaccess_prefix_size(_alignment);
 366 
 367   if (base() && base() + _size > (char *)OopEncodingHeapMax) {
 368     if (true
 369         WIN64_ONLY(&& !UseLargePages)
 370         AIX_ONLY(&& os::vm_page_size() != 64*K)) {
 371       // Protect memory at the base of the allocated region.
 372       // If special, the page was committed (only matters on windows)
 373       if (!os::protect_memory(_base, _noaccess_prefix, os::MEM_PROT_NONE, _special)) {
 374         fatal("cannot protect protection page");
 375       }
 376       log_debug(gc, heap, coops)("Protected page at the reserved heap base: "
 377                                  PTR_FORMAT " / " INTX_FORMAT " bytes",
 378                                  p2i(_base),
 379                                  _noaccess_prefix);
 380       assert(CompressedOops::use_implicit_null_checks() == true, "not initialized?");
 381     } else {
 382       CompressedOops::set_use_implicit_null_checks(false);
 383     }
 384   }
 385 
 386   _base += _noaccess_prefix;
 387   _size -= _noaccess_prefix;
 388   assert(((uintptr_t)_base % _alignment == 0), "must be exactly of required alignment");
 389 }
 390 
 391 // Tries to allocate memory of size 'size' at address requested_address with alignment 'alignment'.
 392 // Does not check whether the reserved memory actually is at requested_address, as the memory returned
 393 // might still fulfill the wishes of the caller.
 394 // Assures the memory is aligned to 'alignment'.
 395 // NOTE: If ReservedHeapSpace already points to some reserved memory this is freed, first.
 396 void ReservedHeapSpace::try_reserve_heap(size_t size,
 397                                          size_t alignment,
 398                                          size_t page_size,
 399                                          char* requested_address) {
 400   if (_base != NULL) {
 401     // We tried before, but we didn't like the address delivered.
 402     release();
 403   }
 404 
 405   // Try to reserve the memory for the heap.
 406   log_trace(gc, heap, coops)("Trying to allocate at address " PTR_FORMAT
 407                              " heap of size " SIZE_FORMAT_HEX,
 408                              p2i(requested_address),
 409                              size);
 410 
 411   reserve(size, alignment, page_size, requested_address, false);
 412 
 413   // Check alignment constraints.
 414   if (is_reserved() && !is_aligned(_base, _alignment)) {
 415     // Base not aligned, retry.
 416     release();
 417   }
 418 }
 419 
 420 void ReservedHeapSpace::try_reserve_range(char *highest_start,
 421                                           char *lowest_start,
 422                                           size_t attach_point_alignment,
 423                                           char *aligned_heap_base_min_address,
 424                                           char *upper_bound,
 425                                           size_t size,
 426                                           size_t alignment,
 427                                           size_t page_size) {
 428   const size_t attach_range = highest_start - lowest_start;
 429   // Cap num_attempts at possible number.
 430   // At least one is possible even for 0 sized attach range.
 431   const uint64_t num_attempts_possible = (attach_range / attach_point_alignment) + 1;
 432   const uint64_t num_attempts_to_try   = MIN2((uint64_t)HeapSearchSteps, num_attempts_possible);
 433 
 434   const size_t stepsize = (attach_range == 0) ? // Only one try.
 435     (size_t) highest_start : align_up(attach_range / num_attempts_to_try, attach_point_alignment);
 436 
 437   // Try attach points from top to bottom.
 438   char* attach_point = highest_start;
 439   while (attach_point >= lowest_start  &&
 440          attach_point <= highest_start &&  // Avoid wrap around.
 441          ((_base == NULL) ||
 442           (_base < aligned_heap_base_min_address || _base + size > upper_bound))) {
 443     try_reserve_heap(size, alignment, page_size, attach_point);
 444     attach_point -= stepsize;
 445   }
 446 }
 447 
 448 #define SIZE_64K  ((uint64_t) UCONST64(      0x10000))
 449 #define SIZE_256M ((uint64_t) UCONST64(   0x10000000))
 450 #define SIZE_32G  ((uint64_t) UCONST64(  0x800000000))
 451 
 452 // Helper for heap allocation. Returns an array with addresses
 453 // (OS-specific) which are suited for disjoint base mode. Array is
 454 // NULL terminated.
 455 static char** get_attach_addresses_for_disjoint_mode() {
 456   static uint64_t addresses[] = {
 457      2 * SIZE_32G,
 458      3 * SIZE_32G,
 459      4 * SIZE_32G,
 460      8 * SIZE_32G,
 461     10 * SIZE_32G,
 462      1 * SIZE_64K * SIZE_32G,
 463      2 * SIZE_64K * SIZE_32G,
 464      3 * SIZE_64K * SIZE_32G,
 465      4 * SIZE_64K * SIZE_32G,
 466     16 * SIZE_64K * SIZE_32G,
 467     32 * SIZE_64K * SIZE_32G,
 468     34 * SIZE_64K * SIZE_32G,
 469     0
 470   };
 471 
 472   // Sort out addresses smaller than HeapBaseMinAddress. This assumes
 473   // the array is sorted.
 474   uint i = 0;
 475   while (addresses[i] != 0 &&
 476          (addresses[i] < OopEncodingHeapMax || addresses[i] < HeapBaseMinAddress)) {
 477     i++;
 478   }
 479   uint start = i;
 480 
 481   // Avoid more steps than requested.
 482   i = 0;
 483   while (addresses[start+i] != 0) {
 484     if (i == HeapSearchSteps) {
 485       addresses[start+i] = 0;
 486       break;
 487     }
 488     i++;
 489   }
 490 
 491   return (char**) &addresses[start];
 492 }
 493 
 494 void ReservedHeapSpace::initialize_compressed_heap(const size_t size, size_t alignment, size_t page_size) {
 495   guarantee(size + noaccess_prefix_size(alignment) <= OopEncodingHeapMax,
 496             "can not allocate compressed oop heap for this size");
 497   guarantee(alignment == MAX2(alignment, (size_t)os::vm_page_size()), "alignment too small");
 498 
 499   const size_t granularity = os::vm_allocation_granularity();
 500   assert((size & (granularity - 1)) == 0,
 501          "size not aligned to os::vm_allocation_granularity()");
 502   assert((alignment & (granularity - 1)) == 0,
 503          "alignment not aligned to os::vm_allocation_granularity()");
 504   assert(alignment == 0 || is_power_of_2((intptr_t)alignment),
 505          "not a power of 2");
 506 
 507   // The necessary attach point alignment for generated wish addresses.
 508   // This is needed to increase the chance of attaching for mmap and shmat.
 509   const size_t os_attach_point_alignment =
 510     AIX_ONLY(SIZE_256M)  // Known shm boundary alignment.
 511     NOT_AIX(os::vm_allocation_granularity());
 512   const size_t attach_point_alignment = lcm(alignment, os_attach_point_alignment);
 513 
 514   char *aligned_heap_base_min_address = (char *)align_up((void *)HeapBaseMinAddress, alignment);
 515   size_t noaccess_prefix = ((aligned_heap_base_min_address + size) > (char*)OopEncodingHeapMax) ?
 516     noaccess_prefix_size(alignment) : 0;
 517 
 518   // Attempt to alloc at user-given address.
 519   if (!FLAG_IS_DEFAULT(HeapBaseMinAddress)) {
 520     try_reserve_heap(size + noaccess_prefix, alignment, page_size, aligned_heap_base_min_address);
 521     if (_base != aligned_heap_base_min_address) { // Enforce this exact address.
 522       release();
 523     }
 524   }
 525 
 526   // Keep heap at HeapBaseMinAddress.
 527   if (_base == NULL) {
 528 
 529     // Try to allocate the heap at addresses that allow efficient oop compression.
 530     // Different schemes are tried, in order of decreasing optimization potential.
 531     //
 532     // For this, try_reserve_heap() is called with the desired heap base addresses.
 533     // A call into the os layer to allocate at a given address can return memory
 534     // at a different address than requested.  Still, this might be memory at a useful
 535     // address. try_reserve_heap() always returns this allocated memory, as only here
 536     // the criteria for a good heap are checked.
 537 
 538     // Attempt to allocate so that we can run without base and scale (32-Bit unscaled compressed oops).
 539     // Give it several tries from top of range to bottom.
 540     if (aligned_heap_base_min_address + size <= (char *)UnscaledOopHeapMax) {
 541 
 542       // Calc address range within we try to attach (range of possible start addresses).
 543       char* const highest_start = align_down((char *)UnscaledOopHeapMax - size, attach_point_alignment);
 544       char* const lowest_start  = align_up(aligned_heap_base_min_address, attach_point_alignment);
 545       try_reserve_range(highest_start, lowest_start, attach_point_alignment,
 546                         aligned_heap_base_min_address, (char *)UnscaledOopHeapMax, size, alignment, page_size);
 547     }
 548 
 549     // zerobased: Attempt to allocate in the lower 32G.
 550     // But leave room for the compressed class pointers, which is allocated above
 551     // the heap.




 552     char *zerobased_max = (char *)OopEncodingHeapMax;
 553     const size_t class_space = align_up(CompressedClassSpaceSize, alignment);
 554     // For small heaps, save some space for compressed class pointer
 555     // space so it can be decoded with no base.
 556     if (UseCompressedClassPointers && !UseSharedSpaces &&
 557         OopEncodingHeapMax <= KlassEncodingMetaspaceMax &&
 558         (uint64_t)(aligned_heap_base_min_address + size + class_space) <= KlassEncodingMetaspaceMax) {
 559       zerobased_max = (char *)OopEncodingHeapMax - class_space;
 560     }
 561 
 562     // Give it several tries from top of range to bottom.
 563     if (aligned_heap_base_min_address + size <= zerobased_max &&    // Zerobased theoretical possible.
 564         ((_base == NULL) ||                        // No previous try succeeded.
 565          (_base + size > zerobased_max))) {        // Unscaled delivered an arbitrary address.
 566 
 567       // Calc address range within we try to attach (range of possible start addresses).
 568       char *const highest_start = align_down(zerobased_max - size, attach_point_alignment);
 569       // Need to be careful about size being guaranteed to be less
 570       // than UnscaledOopHeapMax due to type constraints.
 571       char *lowest_start = aligned_heap_base_min_address;
 572       uint64_t unscaled_end = UnscaledOopHeapMax - size;
 573       if (unscaled_end < UnscaledOopHeapMax) { // unscaled_end wrapped if size is large
 574         lowest_start = MAX2(lowest_start, (char*)unscaled_end);
 575       }
 576       lowest_start = align_up(lowest_start, attach_point_alignment);
 577       try_reserve_range(highest_start, lowest_start, attach_point_alignment,
 578                         aligned_heap_base_min_address, zerobased_max, size, alignment, page_size);
 579     }
 580 
 581     // Now we go for heaps with base != 0.  We need a noaccess prefix to efficiently
 582     // implement null checks.
 583     noaccess_prefix = noaccess_prefix_size(alignment);
 584 
 585     // Try to attach at addresses that are aligned to OopEncodingHeapMax. Disjointbase mode.
 586     char** addresses = get_attach_addresses_for_disjoint_mode();
 587     int i = 0;
 588     while (addresses[i] &&                                 // End of array not yet reached.
 589            ((_base == NULL) ||                             // No previous try succeeded.
 590             (_base + size >  (char *)OopEncodingHeapMax && // Not zerobased or unscaled address.
 591              !CompressedOops::is_disjoint_heap_base_address((address)_base)))) {  // Not disjoint address.
 592       char* const attach_point = addresses[i];
 593       assert(attach_point >= aligned_heap_base_min_address, "Flag support broken");
 594       try_reserve_heap(size + noaccess_prefix, alignment, page_size, attach_point);
 595       i++;
 596     }
 597 
 598     // Last, desperate try without any placement.
 599     if (_base == NULL) {
 600       log_trace(gc, heap, coops)("Trying to allocate at address NULL heap of size " SIZE_FORMAT_HEX, size + noaccess_prefix);
 601       initialize(size + noaccess_prefix, alignment, page_size, NULL, false);
 602     }
 603   }
 604 }
 605 
 606 ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment, size_t page_size, const char* heap_allocation_directory) : ReservedSpace() {
 607 
 608   if (size == 0) {
 609     return;
 610   }
 611 
 612   if (heap_allocation_directory != NULL) {
 613     _fd_for_heap = os::create_file_for_heap(heap_allocation_directory);
 614     if (_fd_for_heap == -1) {
 615       vm_exit_during_initialization(
 616         err_msg("Could not create file for Heap at location %s", heap_allocation_directory));
 617     }
 618     // When there is a backing file directory for this space then whether
 619     // large pages are allocated is up to the filesystem of the backing file.
 620     // If requested, let the user know that explicit large pages can't be used.
 621     if (use_explicit_large_pages(page_size) && large_pages_requested()) {
 622       log_debug(gc, heap)("Cannot allocate explicit large pages for Java Heap when AllocateHeapAt option is set.");
 623     }
 624   }
 625 
 626   // Heap size should be aligned to alignment, too.
 627   guarantee(is_aligned(size, alignment), "set by caller");
 628 
 629   if (UseCompressedOops) {
 630     initialize_compressed_heap(size, alignment, page_size);
 631     if (_size > size) {
 632       // We allocated heap with noaccess prefix.
 633       // It can happen we get a zerobased/unscaled heap with noaccess prefix,
 634       // if we had to try at arbitrary address.
 635       establish_noaccess_prefix();
 636     }
 637   } else {
 638     initialize(size, alignment, page_size, NULL, false);
 639   }
 640 
 641   assert(markWord::encode_pointer_as_mark(_base).decode_pointer() == _base,
 642          "area must be distinguishable from marks for mark-sweep");
 643   assert(markWord::encode_pointer_as_mark(&_base[size]).decode_pointer() == &_base[size],
 644          "area must be distinguishable from marks for mark-sweep");
 645 
 646   if (base() != NULL) {
 647     MemTracker::record_virtual_memory_type((address)base(), mtJavaHeap);
 648   }
 649 
 650   if (_fd_for_heap != -1) {
 651     ::close(_fd_for_heap);
 652   }
 653 }
 654 
 655 MemRegion ReservedHeapSpace::region() const {
 656   return MemRegion((HeapWord*)base(), (HeapWord*)end());
 657 }
 658 
 659 // Reserve space for code segment.  Same as Java heap only we mark this as
 660 // executable.
 661 ReservedCodeSpace::ReservedCodeSpace(size_t r_size,
 662                                      size_t rs_align,
 663                                      size_t rs_page_size) : ReservedSpace() {
 664   initialize(r_size, rs_align, rs_page_size, /*requested address*/ NULL, /*executable*/ true);
 665   MemTracker::record_virtual_memory_type((address)base(), mtCode);
 666 }
 667 
 668 // VirtualSpace
 669 
 670 VirtualSpace::VirtualSpace() {
 671   _low_boundary           = NULL;
 672   _high_boundary          = NULL;
 673   _low                    = NULL;
 674   _high                   = NULL;
 675   _lower_high             = NULL;
 676   _middle_high            = NULL;
 677   _upper_high             = NULL;
 678   _lower_high_boundary    = NULL;
 679   _middle_high_boundary   = NULL;
 680   _upper_high_boundary    = NULL;
 681   _lower_alignment        = 0;
 682   _middle_alignment       = 0;
 683   _upper_alignment        = 0;
 684   _special                = false;
 685   _executable             = false;
 686 }
 687 
 688 
 689 bool VirtualSpace::initialize(ReservedSpace rs, size_t committed_size) {
 690   const size_t max_commit_granularity = os::page_size_for_region_unaligned(rs.size(), 1);
 691   return initialize_with_granularity(rs, committed_size, max_commit_granularity);
 692 }
 693 
 694 bool VirtualSpace::initialize_with_granularity(ReservedSpace rs, size_t committed_size, size_t max_commit_granularity) {
 695   if(!rs.is_reserved()) return false;  // allocation failed.
 696   assert(_low_boundary == NULL, "VirtualSpace already initialized");
 697   assert(max_commit_granularity > 0, "Granularity must be non-zero.");
 698 
 699   _low_boundary  = rs.base();
 700   _high_boundary = low_boundary() + rs.size();
 701 
 702   _low = low_boundary();
 703   _high = low();
 704 
 705   _special = rs.special();
 706   _executable = rs.executable();
 707 
 708   // When a VirtualSpace begins life at a large size, make all future expansion
 709   // and shrinking occur aligned to a granularity of large pages.  This avoids
 710   // fragmentation of physical addresses that inhibits the use of large pages
 711   // by the OS virtual memory system.  Empirically,  we see that with a 4MB
 712   // page size, the only spaces that get handled this way are codecache and
 713   // the heap itself, both of which provide a substantial performance
 714   // boost in many benchmarks when covered by large pages.
 715   //
 716   // No attempt is made to force large page alignment at the very top and
 717   // bottom of the space if they are not aligned so already.
 718   _lower_alignment  = os::vm_page_size();
 719   _middle_alignment = max_commit_granularity;
 720   _upper_alignment  = os::vm_page_size();
 721 
 722   // End of each region
 723   _lower_high_boundary = align_up(low_boundary(), middle_alignment());
 724   _middle_high_boundary = align_down(high_boundary(), middle_alignment());
 725   _upper_high_boundary = high_boundary();
 726 
 727   // High address of each region
 728   _lower_high = low_boundary();
 729   _middle_high = lower_high_boundary();
 730   _upper_high = middle_high_boundary();
 731 
 732   // commit to initial size
 733   if (committed_size > 0) {
 734     if (!expand_by(committed_size)) {
 735       return false;
 736     }
 737   }
 738   return true;
 739 }
 740 
 741 
 742 VirtualSpace::~VirtualSpace() {
 743   release();
 744 }
 745 
 746 
 747 void VirtualSpace::release() {
 748   // This does not release memory it reserved.
 749   // Caller must release via rs.release();
 750   _low_boundary           = NULL;
 751   _high_boundary          = NULL;
 752   _low                    = NULL;
 753   _high                   = NULL;
 754   _lower_high             = NULL;
 755   _middle_high            = NULL;
 756   _upper_high             = NULL;
 757   _lower_high_boundary    = NULL;
 758   _middle_high_boundary   = NULL;
 759   _upper_high_boundary    = NULL;
 760   _lower_alignment        = 0;
 761   _middle_alignment       = 0;
 762   _upper_alignment        = 0;
 763   _special                = false;
 764   _executable             = false;
 765 }
 766 
 767 
 768 size_t VirtualSpace::committed_size() const {
 769   return pointer_delta(high(), low(), sizeof(char));
 770 }
 771 
 772 
 773 size_t VirtualSpace::reserved_size() const {
 774   return pointer_delta(high_boundary(), low_boundary(), sizeof(char));
 775 }
 776 
 777 
 778 size_t VirtualSpace::uncommitted_size()  const {
 779   return reserved_size() - committed_size();
 780 }
 781 
 782 size_t VirtualSpace::actual_committed_size() const {
 783   // Special VirtualSpaces commit all reserved space up front.
 784   if (special()) {
 785     return reserved_size();
 786   }
 787 
 788   size_t committed_low    = pointer_delta(_lower_high,  _low_boundary,         sizeof(char));
 789   size_t committed_middle = pointer_delta(_middle_high, _lower_high_boundary,  sizeof(char));
 790   size_t committed_high   = pointer_delta(_upper_high,  _middle_high_boundary, sizeof(char));
 791 
 792 #ifdef ASSERT
 793   size_t lower  = pointer_delta(_lower_high_boundary,  _low_boundary,         sizeof(char));
 794   size_t middle = pointer_delta(_middle_high_boundary, _lower_high_boundary,  sizeof(char));
 795   size_t upper  = pointer_delta(_upper_high_boundary,  _middle_high_boundary, sizeof(char));
 796 
 797   if (committed_high > 0) {
 798     assert(committed_low == lower, "Must be");
 799     assert(committed_middle == middle, "Must be");
 800   }
 801 
 802   if (committed_middle > 0) {
 803     assert(committed_low == lower, "Must be");
 804   }
 805   if (committed_middle < middle) {
 806     assert(committed_high == 0, "Must be");
 807   }
 808 
 809   if (committed_low < lower) {
 810     assert(committed_high == 0, "Must be");
 811     assert(committed_middle == 0, "Must be");
 812   }
 813 #endif
 814 
 815   return committed_low + committed_middle + committed_high;
 816 }
 817 
 818 
 819 bool VirtualSpace::contains(const void* p) const {
 820   return low() <= (const char*) p && (const char*) p < high();
 821 }
 822 
 823 static void pretouch_expanded_memory(void* start, void* end) {
 824   assert(is_aligned(start, os::vm_page_size()), "Unexpected alignment");
 825   assert(is_aligned(end,   os::vm_page_size()), "Unexpected alignment");
 826 
 827   os::pretouch_memory(start, end);
 828 }
 829 
 830 static bool commit_expanded(char* start, size_t size, size_t alignment, bool pre_touch, bool executable) {
 831   if (os::commit_memory(start, size, alignment, executable)) {
 832     if (pre_touch || AlwaysPreTouch) {
 833       pretouch_expanded_memory(start, start + size);
 834     }
 835     return true;
 836   }
 837 
 838   debug_only(warning(
 839       "INFO: os::commit_memory(" PTR_FORMAT ", " PTR_FORMAT
 840       " size=" SIZE_FORMAT ", executable=%d) failed",
 841       p2i(start), p2i(start + size), size, executable);)
 842 
 843   return false;
 844 }
 845 
 846 /*
 847    First we need to determine if a particular virtual space is using large
 848    pages.  This is done at the initialize function and only virtual spaces
 849    that are larger than LargePageSizeInBytes use large pages.  Once we
 850    have determined this, all expand_by and shrink_by calls must grow and
 851    shrink by large page size chunks.  If a particular request
 852    is within the current large page, the call to commit and uncommit memory
 853    can be ignored.  In the case that the low and high boundaries of this
 854    space is not large page aligned, the pages leading to the first large
 855    page address and the pages after the last large page address must be
 856    allocated with default pages.
 857 */
 858 bool VirtualSpace::expand_by(size_t bytes, bool pre_touch) {
 859   if (uncommitted_size() < bytes) {
 860     return false;
 861   }
 862 
 863   if (special()) {
 864     // don't commit memory if the entire space is pinned in memory
 865     _high += bytes;
 866     return true;
 867   }
 868 
 869   char* previous_high = high();
 870   char* unaligned_new_high = high() + bytes;
 871   assert(unaligned_new_high <= high_boundary(), "cannot expand by more than upper boundary");
 872 
 873   // Calculate where the new high for each of the regions should be.  If
 874   // the low_boundary() and high_boundary() are LargePageSizeInBytes aligned
 875   // then the unaligned lower and upper new highs would be the
 876   // lower_high() and upper_high() respectively.
 877   char* unaligned_lower_new_high =  MIN2(unaligned_new_high, lower_high_boundary());
 878   char* unaligned_middle_new_high = MIN2(unaligned_new_high, middle_high_boundary());
 879   char* unaligned_upper_new_high =  MIN2(unaligned_new_high, upper_high_boundary());
 880 
 881   // Align the new highs based on the regions alignment.  lower and upper
 882   // alignment will always be default page size.  middle alignment will be
 883   // LargePageSizeInBytes if the actual size of the virtual space is in
 884   // fact larger than LargePageSizeInBytes.
 885   char* aligned_lower_new_high =  align_up(unaligned_lower_new_high, lower_alignment());
 886   char* aligned_middle_new_high = align_up(unaligned_middle_new_high, middle_alignment());
 887   char* aligned_upper_new_high =  align_up(unaligned_upper_new_high, upper_alignment());
 888 
 889   // Determine which regions need to grow in this expand_by call.
 890   // If you are growing in the lower region, high() must be in that
 891   // region so calculate the size based on high().  For the middle and
 892   // upper regions, determine the starting point of growth based on the
 893   // location of high().  By getting the MAX of the region's low address
 894   // (or the previous region's high address) and high(), we can tell if it
 895   // is an intra or inter region growth.
 896   size_t lower_needs = 0;
 897   if (aligned_lower_new_high > lower_high()) {
 898     lower_needs = pointer_delta(aligned_lower_new_high, lower_high(), sizeof(char));
 899   }
 900   size_t middle_needs = 0;
 901   if (aligned_middle_new_high > middle_high()) {
 902     middle_needs = pointer_delta(aligned_middle_new_high, middle_high(), sizeof(char));
 903   }
 904   size_t upper_needs = 0;
 905   if (aligned_upper_new_high > upper_high()) {
 906     upper_needs = pointer_delta(aligned_upper_new_high, upper_high(), sizeof(char));
 907   }
 908 
 909   // Check contiguity.
 910   assert(low_boundary() <= lower_high() && lower_high() <= lower_high_boundary(),
 911          "high address must be contained within the region");
 912   assert(lower_high_boundary() <= middle_high() && middle_high() <= middle_high_boundary(),
 913          "high address must be contained within the region");
 914   assert(middle_high_boundary() <= upper_high() && upper_high() <= upper_high_boundary(),
 915          "high address must be contained within the region");
 916 
 917   // Commit regions
 918   if (lower_needs > 0) {
 919     assert(lower_high() + lower_needs <= lower_high_boundary(), "must not expand beyond region");
 920     if (!commit_expanded(lower_high(), lower_needs, _lower_alignment, pre_touch, _executable)) {
 921       return false;
 922     }
 923     _lower_high += lower_needs;
 924   }
 925 
 926   if (middle_needs > 0) {
 927     assert(middle_high() + middle_needs <= middle_high_boundary(), "must not expand beyond region");
 928     if (!commit_expanded(middle_high(), middle_needs, _middle_alignment, pre_touch, _executable)) {
 929       return false;
 930     }
 931     _middle_high += middle_needs;
 932   }
 933 
 934   if (upper_needs > 0) {
 935     assert(upper_high() + upper_needs <= upper_high_boundary(), "must not expand beyond region");
 936     if (!commit_expanded(upper_high(), upper_needs, _upper_alignment, pre_touch, _executable)) {
 937       return false;
 938     }
 939     _upper_high += upper_needs;
 940   }
 941 
 942   _high += bytes;
 943   return true;
 944 }
 945 
 946 // A page is uncommitted if the contents of the entire page is deemed unusable.
 947 // Continue to decrement the high() pointer until it reaches a page boundary
 948 // in which case that particular page can now be uncommitted.
 949 void VirtualSpace::shrink_by(size_t size) {
 950   if (committed_size() < size)
 951     fatal("Cannot shrink virtual space to negative size");
 952 
 953   if (special()) {
 954     // don't uncommit if the entire space is pinned in memory
 955     _high -= size;
 956     return;
 957   }
 958 
 959   char* unaligned_new_high = high() - size;
 960   assert(unaligned_new_high >= low_boundary(), "cannot shrink past lower boundary");
 961 
 962   // Calculate new unaligned address
 963   char* unaligned_upper_new_high =
 964     MAX2(unaligned_new_high, middle_high_boundary());
 965   char* unaligned_middle_new_high =
 966     MAX2(unaligned_new_high, lower_high_boundary());
 967   char* unaligned_lower_new_high =
 968     MAX2(unaligned_new_high, low_boundary());
 969 
 970   // Align address to region's alignment
 971   char* aligned_upper_new_high =  align_up(unaligned_upper_new_high, upper_alignment());
 972   char* aligned_middle_new_high = align_up(unaligned_middle_new_high, middle_alignment());
 973   char* aligned_lower_new_high =  align_up(unaligned_lower_new_high, lower_alignment());
 974 
 975   // Determine which regions need to shrink
 976   size_t upper_needs = 0;
 977   if (aligned_upper_new_high < upper_high()) {
 978     upper_needs =
 979       pointer_delta(upper_high(), aligned_upper_new_high, sizeof(char));
 980   }
 981   size_t middle_needs = 0;
 982   if (aligned_middle_new_high < middle_high()) {
 983     middle_needs =
 984       pointer_delta(middle_high(), aligned_middle_new_high, sizeof(char));
 985   }
 986   size_t lower_needs = 0;
 987   if (aligned_lower_new_high < lower_high()) {
 988     lower_needs =
 989       pointer_delta(lower_high(), aligned_lower_new_high, sizeof(char));
 990   }
 991 
 992   // Check contiguity.
 993   assert(middle_high_boundary() <= upper_high() &&
 994          upper_high() <= upper_high_boundary(),
 995          "high address must be contained within the region");
 996   assert(lower_high_boundary() <= middle_high() &&
 997          middle_high() <= middle_high_boundary(),
 998          "high address must be contained within the region");
 999   assert(low_boundary() <= lower_high() &&
1000          lower_high() <= lower_high_boundary(),
1001          "high address must be contained within the region");
1002 
1003   // Uncommit
1004   if (upper_needs > 0) {
1005     assert(middle_high_boundary() <= aligned_upper_new_high &&
1006            aligned_upper_new_high + upper_needs <= upper_high_boundary(),
1007            "must not shrink beyond region");
1008     if (!os::uncommit_memory(aligned_upper_new_high, upper_needs, _executable)) {
1009       debug_only(warning("os::uncommit_memory failed"));
1010       return;
1011     } else {
1012       _upper_high -= upper_needs;
1013     }
1014   }
1015   if (middle_needs > 0) {
1016     assert(lower_high_boundary() <= aligned_middle_new_high &&
1017            aligned_middle_new_high + middle_needs <= middle_high_boundary(),
1018            "must not shrink beyond region");
1019     if (!os::uncommit_memory(aligned_middle_new_high, middle_needs, _executable)) {
1020       debug_only(warning("os::uncommit_memory failed"));
1021       return;
1022     } else {
1023       _middle_high -= middle_needs;
1024     }
1025   }
1026   if (lower_needs > 0) {
1027     assert(low_boundary() <= aligned_lower_new_high &&
1028            aligned_lower_new_high + lower_needs <= lower_high_boundary(),
1029            "must not shrink beyond region");
1030     if (!os::uncommit_memory(aligned_lower_new_high, lower_needs, _executable)) {
1031       debug_only(warning("os::uncommit_memory failed"));
1032       return;
1033     } else {
1034       _lower_high -= lower_needs;
1035     }
1036   }
1037 
1038   _high -= size;
1039 }
1040 
1041 #ifndef PRODUCT
1042 void VirtualSpace::check_for_contiguity() {
1043   // Check contiguity.
1044   assert(low_boundary() <= lower_high() &&
1045          lower_high() <= lower_high_boundary(),
1046          "high address must be contained within the region");
1047   assert(lower_high_boundary() <= middle_high() &&
1048          middle_high() <= middle_high_boundary(),
1049          "high address must be contained within the region");
1050   assert(middle_high_boundary() <= upper_high() &&
1051          upper_high() <= upper_high_boundary(),
1052          "high address must be contained within the region");
1053   assert(low() >= low_boundary(), "low");
1054   assert(low_boundary() <= lower_high_boundary(), "lower high boundary");
1055   assert(upper_high_boundary() <= high_boundary(), "upper high boundary");
1056   assert(high() <= upper_high(), "upper high");
1057 }
1058 
1059 void VirtualSpace::print_on(outputStream* out) const {
1060   out->print   ("Virtual space:");
1061   if (special()) out->print(" (pinned in memory)");
1062   out->cr();
1063   out->print_cr(" - committed: " SIZE_FORMAT, committed_size());
1064   out->print_cr(" - reserved:  " SIZE_FORMAT, reserved_size());
1065   out->print_cr(" - [low, high]:     [" INTPTR_FORMAT ", " INTPTR_FORMAT "]",  p2i(low()), p2i(high()));
1066   out->print_cr(" - [low_b, high_b]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]",  p2i(low_boundary()), p2i(high_boundary()));
1067 }
1068 
1069 void VirtualSpace::print() const {
1070   print_on(tty);
1071 }
1072 
1073 #endif
--- EOF ---