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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 | /* * Copyright (c) 2021 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ #if defined(__LP64__) /* * Userspace functions for manipulating the reclaim buffer. */ #include <inttypes.h> #include <stdbool.h> #include <stdlib.h> #include <mach/error.h> #include <mach/kern_return.h> #include <mach/mach.h> #include <mach/mach_time.h> #include <mach/mach_traps.h> #include <mach/mach_vm.h> #include <mach/vm_reclaim_private.h> #undef _mach_vm_user_ #include <mach/mach_vm_internal.h> #include <mach/vm_map.h> #include <mach/vm_page_size.h> #include <os/atomic_private.h> #include <os/overflow.h> #include <sys/param.h> #include <TargetConditionals.h> #pragma mark Utilities #define _assert(__op, __condition, __cause) \ do { \ if (!(__condition)) { \ __builtin_trap(); \ } \ } while (false) #define _abort(__op, __cause) \ do { \ __builtin_trap(); \ } while(false) _Static_assert(VM_RECLAIM_MAX_CAPACITY <= UINT32_MAX, "Max capacity must fit in mach_vm_reclaim_count_t"); static inline struct mach_vm_reclaim_entry_s construct_entry( mach_vm_address_t start_addr, uint32_t size, mach_vm_reclaim_action_t behavior) { struct mach_vm_reclaim_entry_s entry = {0ULL}; entry.address = start_addr; entry.size = size; entry.behavior = behavior; return entry; } static uint64_t max_buffer_len_for_size(mach_vm_size_t size) { mach_vm_size_t entries_size = size - offsetof(struct mach_vm_reclaim_ring_s, entries); return entries_size / sizeof(struct mach_vm_reclaim_entry_s); } static mach_vm_reclaim_count_t round_buffer_len(mach_vm_reclaim_count_t count) { mach_vm_reclaim_count_t rounded_count; mach_vm_size_t buffer_size = offsetof(struct mach_vm_reclaim_ring_s, entries) + (count * sizeof(struct mach_vm_reclaim_entry_s)); mach_vm_size_t rounded_size = mach_vm_round_page(buffer_size); uint64_t num_entries = max_buffer_len_for_size(rounded_size); if (os_convert_overflow(num_entries, &rounded_count)) { return UINT32_MAX; } return rounded_count; } mach_vm_reclaim_error_t mach_vm_reclaim_ring_allocate( mach_vm_reclaim_ring_t *ring_out, mach_vm_reclaim_count_t initial_capacity, mach_vm_reclaim_count_t max_capacity) { kern_return_t kr; mach_vm_address_t vm_addr = 0; uint64_t next_deadline = 0, now; if (ring_out == NULL || max_capacity < initial_capacity || initial_capacity == 0 || max_capacity == 0) { return VM_RECLAIM_INVALID_ARGUMENT; } if (max_capacity > VM_RECLAIM_MAX_CAPACITY) { return VM_RECLAIM_INVALID_CAPACITY; } *ring_out = NULL; now = mach_absolute_time(); kr = mach_vm_deferred_reclamation_buffer_allocate(mach_task_self(), &vm_addr, &next_deadline, initial_capacity, max_capacity); if (kr == ERR_SUCCESS) { mach_vm_reclaim_ring_t ring = (mach_vm_reclaim_ring_t)vm_addr; ring->len = initial_capacity; ring->max_len = max_capacity; os_atomic_store(&ring->last_sample_abs, now, relaxed); os_atomic_store(&ring->reclaimable_bytes, 0, relaxed); os_atomic_store(&ring->reclaimable_bytes_min, 0, relaxed); os_atomic_store(&ring->next_sample_deadline_abs, next_deadline, relaxed); *ring_out = ring; } return kr; } mach_vm_reclaim_error_t mach_vm_reclaim_ring_resize( mach_vm_reclaim_ring_t ring, mach_vm_reclaim_count_t capacity) { mach_error_t err; mach_vm_size_t bytes_reclaimed = 0; uint64_t next_deadline; if (ring == NULL) { return VM_RECLAIM_INVALID_RING; } if (capacity == 0 || capacity > ring->max_len) { return VM_RECLAIM_INVALID_CAPACITY; } err = mach_vm_deferred_reclamation_buffer_resize(mach_task_self(), capacity, &bytes_reclaimed, &next_deadline); if (err == ERR_SUCCESS) { ring->len = capacity; size_t reclaimable_bytes = os_atomic_sub(&ring->reclaimable_bytes, bytes_reclaimed, relaxed); os_atomic_min(&ring->reclaimable_bytes_min, reclaimable_bytes, relaxed); os_atomic_max(&ring->next_sample_deadline_abs, next_deadline, relaxed); } return err; } mach_vm_reclaim_count_t mach_vm_reclaim_round_capacity( mach_vm_reclaim_count_t count) { if (count > VM_RECLAIM_MAX_CAPACITY) { return VM_RECLAIM_MAX_CAPACITY; } return round_buffer_len(count); } mach_vm_reclaim_error_t mach_vm_reclaim_try_enter( mach_vm_reclaim_ring_t ring, mach_vm_address_t region_start, mach_vm_size_t region_size, mach_vm_reclaim_action_t action, mach_vm_reclaim_id_t *id, bool *should_update_kernel_accounting) { mach_vm_reclaim_id_t tail = 0, head = 0, original_tail = 0, busy = 0; mach_vm_reclaim_entry_t entries = ring->entries; uint64_t buffer_len = (uint64_t)ring->len; *should_update_kernel_accounting = false; if (ring == NULL) { return VM_RECLAIM_INVALID_RING; } if (id == NULL) { return VM_RECLAIM_INVALID_ID; } uint32_t size32; if (os_convert_overflow(region_size, &size32)) { /* regions must fit in 32-bits */ *id = VM_RECLAIM_ID_NULL; return VM_RECLAIM_INVALID_REGION_SIZE; } mach_vm_reclaim_id_t requested_id = *id; *id = VM_RECLAIM_ID_NULL; if (requested_id == VM_RECLAIM_ID_NULL) { tail = os_atomic_load_wide(&ring->tail, relaxed); head = os_atomic_load_wide(&ring->head, relaxed); if (tail % buffer_len == head % buffer_len && tail > head) { /* Buffer is full */ return VM_RECLAIM_SUCCESS; } /* * idx must be >= head & the buffer is not full so it's not possible for the kernel to be acting on the entry at (tail + 1) % size. * Thus we don't need to check the busy pointer here. */ struct mach_vm_reclaim_entry_s entry = construct_entry(region_start, size32, action); entries[tail % buffer_len] = entry; os_atomic_thread_fence(seq_cst); // tail increment can not be seen before the entry is cleared in the buffer os_atomic_inc(&ring->tail, relaxed); *id = tail; } else { head = os_atomic_load_wide(&ring->head, relaxed); if (requested_id < head) { /* * This is just a fast path for the case where the buffer has wrapped. * It's not strictly necessary beacuse idx must also be < busy. * That's why we can use a relaxed load for the head ptr. */ return VM_RECLAIM_SUCCESS; } /* Attempt to move tail to idx */ original_tail = os_atomic_load_wide(&ring->tail, relaxed); _assert("mach_vm_reclaim_mark_free_with_id", requested_id < original_tail, original_tail); os_atomic_store_wide(&ring->tail, requested_id, relaxed); os_atomic_thread_fence(seq_cst); // Our write to tail must happen before our read of busy busy = os_atomic_load_wide(&ring->busy, relaxed); if (requested_id < busy) { /* Kernel is acting on this entry. Undo. */ os_atomic_store_wide(&ring->tail, original_tail, relaxed); return VM_RECLAIM_SUCCESS; } mach_vm_reclaim_entry_t entry = &entries[requested_id % buffer_len]; _assert("mach_vm_reclaim_try_enter", entry->address == 0 && entry->size == 0, entry->address); /* Sucessfully moved tail back. Can now overwrite the entry */ *entry = construct_entry(region_start, size32, action); /* Tail increment can not be seen before the entry is set in the buffer */ os_atomic_thread_fence(seq_cst); /* Reset tail. */ os_atomic_store_wide(&ring->tail, original_tail, relaxed); *id = requested_id; } size_t reclaimable_bytes = os_atomic_add(&ring->reclaimable_bytes, region_size, relaxed); os_atomic_min(&ring->reclaimable_bytes_min, reclaimable_bytes, relaxed); uint64_t now = mach_absolute_time(); if (now >= os_atomic_load(&ring->next_sample_deadline_abs, relaxed)) { *should_update_kernel_accounting = true; } return VM_RECLAIM_SUCCESS; } mach_vm_reclaim_error_t mach_vm_reclaim_try_cancel( mach_vm_reclaim_ring_t ring, mach_vm_reclaim_id_t id, mach_vm_address_t region_start, mach_vm_size_t region_size, mach_vm_reclaim_action_t behavior, mach_vm_reclaim_state_t *state, bool *should_update_kernel_accounting) { mach_vm_reclaim_entry_t entries = ring->entries; uint64_t buffer_len = (uint64_t)ring->len; uint64_t head = 0, busy = 0, original_tail = 0; if (ring == NULL) { return VM_RECLAIM_INVALID_RING; } if (id == VM_RECLAIM_ID_NULL) { /* The entry was never put in the reclaim ring buffer */ return VM_RECLAIM_INVALID_ID; } if (state == NULL || should_update_kernel_accounting == NULL) { return VM_RECLAIM_INVALID_ARGUMENT; } *should_update_kernel_accounting = false; uint32_t size32; if (os_convert_overflow(region_size, &size32)) { /* Regions must fit in 32-bits */ return VM_RECLAIM_INVALID_REGION_SIZE; } head = os_atomic_load_wide(&ring->head, relaxed); if (id < head) { /* * This is just a fast path for the case where the buffer has wrapped. * It's not strictly necessary beacuse idx must also be < busy. * That's why we can use a relaxed load for the head ptr. */ switch (behavior) { case VM_RECLAIM_DEALLOCATE: /* Entry has been deallocated and is not safe to re-use */ *state = VM_RECLAIM_DEALLOCATED; break; case VM_RECLAIM_FREE: /* Entry has been freed, the virtual region is now safe to re-use */ *state = VM_RECLAIM_FREED; break; default: return VM_RECLAIM_INVALID_ARGUMENT; } return VM_RECLAIM_SUCCESS; } /* Attempt to move tail to idx */ original_tail = os_atomic_load_wide(&ring->tail, relaxed); _assert("mach_vm_reclaim_mark_used", id < original_tail, original_tail); os_atomic_store_wide(&ring->tail, id, relaxed); /* Our write to tail must happen before our read of busy */ os_atomic_thread_fence(seq_cst); busy = os_atomic_load_wide(&ring->busy, relaxed); if (id < busy) { /* * This entry is in the process of being reclaimed. It is * never safe to re-use while in this state. */ os_atomic_store_wide(&ring->tail, original_tail, relaxed); *state = VM_RECLAIM_BUSY; return VM_RECLAIM_SUCCESS; } mach_vm_reclaim_entry_t entry = &entries[id % buffer_len]; _assert("mach_vm_reclaim_mark_used", entry->size == region_size, entry->size); _assert("mach_vm_reclaim_mark_used", entry->address == region_start, entry->address); _assert("mach_vm_reclaim_mark_used", entry->behavior == behavior, entry->behavior); /* Sucessfully moved tail back. Can now overwrite the entry */ memset(entry, 0, sizeof(struct mach_vm_reclaim_entry_s)); /* tail increment can not be seen before the entry is cleared in the buffer */ os_atomic_thread_fence(seq_cst); /* Reset tail. */ os_atomic_store_wide(&ring->tail, original_tail, relaxed); size_t reclaimable_bytes = os_atomic_sub(&ring->reclaimable_bytes, region_size, relaxed); os_atomic_min(&ring->reclaimable_bytes_min, reclaimable_bytes, relaxed); uint64_t now = mach_absolute_time(); if (now >= os_atomic_load(&ring->next_sample_deadline_abs, relaxed)) { *should_update_kernel_accounting = true; } *state = VM_RECLAIM_UNRECLAIMED; return VM_RECLAIM_SUCCESS; } mach_vm_reclaim_error_t mach_vm_reclaim_query_state( mach_vm_reclaim_ring_t ring, mach_vm_reclaim_id_t id, mach_vm_reclaim_action_t action, mach_vm_reclaim_state_t *state) { if (ring == NULL) { return VM_RECLAIM_INVALID_RING; } if (id == VM_RECLAIM_ID_NULL) { return VM_RECLAIM_INVALID_ID; } mach_vm_reclaim_id_t head = os_atomic_load_wide(&ring->head, relaxed); if (id < head) { switch (action) { case VM_RECLAIM_FREE: *state = VM_RECLAIM_FREED; break; case VM_RECLAIM_DEALLOCATE: *state = VM_RECLAIM_DEALLOCATED; break; default: return VM_RECLAIM_INVALID_ARGUMENT; } return VM_RECLAIM_SUCCESS; } mach_vm_reclaim_id_t busy = os_atomic_load_wide(&ring->busy, relaxed); if (id < busy) { *state = VM_RECLAIM_BUSY; } else { *state = VM_RECLAIM_UNRECLAIMED; } return VM_RECLAIM_SUCCESS; } mach_vm_reclaim_error_t mach_vm_reclaim_update_kernel_accounting(const mach_vm_reclaim_ring_t ring) { /* * The rmw on last_sample is an optimization to prevent a herd of threads * all calling into the kernel and contending on the kernel lock after the * deadline has expired and before any (potentially slow) reclamation * operations have completed */ uint64_t last_sample; uint64_t now = mach_absolute_time(); uint64_t prev_deadline = os_atomic_load(&ring->next_sample_deadline_abs, relaxed); os_atomic_rmw_loop(&ring->last_sample_abs, last_sample, now, relaxed, { if (last_sample >= prev_deadline) { /* Another thread beat us to taking a sample */ os_atomic_rmw_loop_give_up(return VM_RECLAIM_SUCCESS; ); } }); mach_error_t err; uint64_t bytes_reclaimed = 0; uint64_t next_deadline = 0; err = mach_vm_reclaim_update_kernel_accounting_trap(current_task(), &bytes_reclaimed, &next_deadline); mach_vm_size_t reclaimable_bytes = os_atomic_sub(&ring->reclaimable_bytes, bytes_reclaimed, relaxed); os_atomic_min(&ring->reclaimable_bytes_min, reclaimable_bytes, relaxed); if (err == ERR_SUCCESS) { os_atomic_max(&ring->next_sample_deadline_abs, next_deadline, relaxed); } return err; } bool mach_vm_reclaim_is_reusable( mach_vm_reclaim_state_t state) { switch (state) { case VM_RECLAIM_FREED: case VM_RECLAIM_UNRECLAIMED: return true; case VM_RECLAIM_DEALLOCATED: case VM_RECLAIM_BUSY: return false; default: return false; } } mach_vm_reclaim_error_t mach_vm_reclaim_ring_capacity(mach_vm_reclaim_ring_t ring, mach_vm_reclaim_count_t *capacity) { if (ring == NULL) { return VM_RECLAIM_INVALID_RING; } if (capacity == NULL) { return VM_RECLAIM_INVALID_ARGUMENT; } *capacity = ring->len; return VM_RECLAIM_SUCCESS; } mach_vm_reclaim_error_t mach_vm_reclaim_ring_flush( mach_vm_reclaim_ring_t ring, mach_vm_reclaim_count_t num_entries_to_reclaim) { mach_vm_size_t bytes_reclaimed; uint64_t next_deadline; mach_error_t err; if (ring == NULL) { return VM_RECLAIM_INVALID_RING; } if (num_entries_to_reclaim == 0) { return VM_RECLAIM_INVALID_ARGUMENT; } err = mach_vm_deferred_reclamation_buffer_flush(mach_task_self(), num_entries_to_reclaim, &bytes_reclaimed, &next_deadline); if (err == ERR_SUCCESS) { size_t reclaimable_bytes = os_atomic_sub(&ring->reclaimable_bytes, bytes_reclaimed, relaxed); os_atomic_min(&ring->reclaimable_bytes_min, reclaimable_bytes, relaxed); os_atomic_max(&ring->next_sample_deadline_abs, next_deadline, relaxed); } return err; } mach_vm_reclaim_error_t mach_vm_reclaim_get_rings_for_task( task_read_t task, mach_vm_reclaim_ring_ref_t refs_out, mach_vm_reclaim_count_t *count_inout) { /* * Technically, we could support multiple rings per task. But for now, we * only have one - so this is kind of a weird-looking shim that fakes that * behavior at the libsyscall layer to make things easier in case anything * changes. */ kern_return_t kr; mach_vm_address_t addr; mach_vm_size_t size; if (count_inout == NULL) { return VM_RECLAIM_INVALID_ARGUMENT; } kr = mach_vm_deferred_reclamation_buffer_query(task, &addr, &size); if (kr != KERN_SUCCESS) { switch (kr) { case KERN_NOT_SUPPORTED: return VM_RECLAIM_NOT_SUPPORTED; case KERN_INVALID_ARGUMENT: case KERN_INVALID_TASK: case KERN_INVALID_ADDRESS: return VM_RECLAIM_INVALID_ARGUMENT; default: return kr; } } /* Size query. If addr == NULL, it doesn't have a ring */ if (refs_out == NULL) { *count_inout = addr ? 1 : 0; return KERN_SUCCESS; } if (addr) { if (*count_inout >= 1) { refs_out->addr = addr; refs_out->size = size; } *count_inout = 1; } else { *count_inout = 0; } return KERN_SUCCESS; } static mach_vm_reclaim_error_t verify_ring_allocation_size(mach_vm_address_t addr, mach_vm_size_t size) { if (size < offsetof(struct mach_vm_reclaim_ring_s, entries)) { return VM_RECLAIM_INVALID_RING; } mach_vm_reclaim_ring_t ring = (mach_vm_reclaim_ring_t) addr; mach_vm_size_t supposed_size = offsetof(struct mach_vm_reclaim_ring_s, entries) + (ring->max_len * sizeof(struct mach_vm_reclaim_entry_s)); /* store allocation size in ring->_unused so that we can free it later */ ring->_unused = size; return (supposed_size <= size) ? VM_RECLAIM_SUCCESS : VM_RECLAIM_INVALID_RING; } mach_vm_reclaim_error_t mach_vm_reclaim_ring_copy( task_read_t task, mach_vm_reclaim_ring_ref_t ref, mach_vm_reclaim_ring_copy_t *ring_out) { mach_vm_address_t address; vm_prot_t curprot = VM_PROT_DEFAULT; vm_prot_t maxprot = VM_PROT_DEFAULT; kern_return_t kr = mach_vm_remap( mach_task_self(), &address, ref->size, 0, VM_FLAGS_ANYWHERE, task, ref->addr, TRUE, &curprot, &maxprot, VM_INHERIT_DEFAULT); switch (kr) { case KERN_INVALID_TASK: case KERN_INVALID_ADDRESS: case KERN_INVALID_ARGUMENT: return VM_RECLAIM_INVALID_ARGUMENT; case KERN_SUCCESS: break; default: return kr; } kr = verify_ring_allocation_size(address, ref->size); if (kr != VM_RECLAIM_SUCCESS) { return kr; } *ring_out = address; return VM_RECLAIM_SUCCESS; } mach_vm_reclaim_error_t mach_vm_reclaim_copied_ring_free( mach_vm_reclaim_ring_copy_t *cring) { kern_return_t kr; mach_vm_reclaim_ring_t ring = (mach_vm_reclaim_ring_t) *cring; kr = mach_vm_deallocate( mach_task_self(), (mach_vm_address_t) *cring, ring->_unused); if (kr == KERN_SUCCESS) { *cring = NULL; } return kr; } mach_vm_reclaim_error_t mach_vm_reclaim_copied_ring_query( mach_vm_reclaim_ring_copy_t *ring_copy, mach_vm_reclaim_region_t regions_out, mach_vm_reclaim_count_t *count_inout) { mach_vm_reclaim_id_t head, tail, idx, entry_idx; mach_vm_reclaim_entry_t entry; mach_vm_reclaim_count_t count; mach_vm_reclaim_ring_t ring = (mach_vm_reclaim_ring_t) *ring_copy; if (ring == NULL) { return VM_RECLAIM_INVALID_RING; } if (count_inout == NULL) { return VM_RECLAIM_INVALID_ARGUMENT; } head = os_atomic_load_wide(&ring->head, relaxed); tail = os_atomic_load_wide(&ring->tail, relaxed); if (tail < head) { *count_inout = 0; return VM_RECLAIM_SUCCESS; } count = (mach_vm_reclaim_count_t) (tail - head); /* Query size */ if (regions_out == NULL) { *count_inout = count; return VM_RECLAIM_SUCCESS; } count = (count < *count_inout) ? count : *count_inout; for (idx = 0; idx < count; idx++) { entry_idx = (head + idx) % ring->len; if (entry_idx > ring->max_len) { /* * Make sure we don't accidentally read outside of the mapped region * due to a malformed ring */ *count_inout = (mach_vm_reclaim_count_t) idx; return VM_RECLAIM_INVALID_CAPACITY; } entry = &ring->entries[entry_idx]; regions_out->vmrr_addr = entry->address; regions_out->vmrr_size = entry->size; regions_out->vmrr_behavior = entry->behavior; regions_out++; } *count_inout = count; return VM_RECLAIM_SUCCESS; } #endif /* defined(__LP64__) */ |