subr_kmem.c revision 1.74
1 /* $NetBSD: subr_kmem.c,v 1.74 2019/03/26 20:05:18 maxv Exp $ */ 2 3 /*- 4 * Copyright (c) 2009-2015 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Andrew Doran and Maxime Villard. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /*- 33 * Copyright (c)2006 YAMAMOTO Takashi, 34 * All rights reserved. 35 * 36 * Redistribution and use in source and binary forms, with or without 37 * modification, are permitted provided that the following conditions 38 * are met: 39 * 1. Redistributions of source code must retain the above copyright 40 * notice, this list of conditions and the following disclaimer. 41 * 2. Redistributions in binary form must reproduce the above copyright 42 * notice, this list of conditions and the following disclaimer in the 43 * documentation and/or other materials provided with the distribution. 44 * 45 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 46 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 47 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 48 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 49 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 50 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 51 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 52 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 53 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 54 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 55 * SUCH DAMAGE. 56 */ 57 58 /* 59 * Allocator of kernel wired memory. This allocator has some debug features 60 * enabled with "option DIAGNOSTIC" and "option DEBUG". 61 */ 62 63 /* 64 * KMEM_SIZE: detect alloc/free size mismatch bugs. 65 * Prefix each allocations with a fixed-sized, aligned header and record 66 * the exact user-requested allocation size in it. When freeing, compare 67 * it with kmem_free's "size" argument. 68 * 69 * This option enabled on DIAGNOSTIC. 70 * 71 * |CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK| 72 * +-----+-----+-----+-----+-----+-----+-----+-----+-----+---+-+ 73 * |/////| | | | | | | | | |U| 74 * |/HSZ/| | | | | | | | | |U| 75 * |/////| | | | | | | | | |U| 76 * +-----+-----+-----+-----+-----+-----+-----+-----+-----+---+-+ 77 * |Size | Buffer usable by the caller (requested size) |Unused\ 78 */ 79 80 /* 81 * KMEM_GUARD 82 * A kernel with "option DEBUG" has "kmem_guard" debugging feature compiled 83 * in. See the comment below for what kind of bugs it tries to detect. Even 84 * if compiled in, it's disabled by default because it's very expensive. 85 * You can enable it on boot by: 86 * boot -d 87 * db> w kmem_guard_depth 0t30000 88 * db> c 89 * 90 * The default value of kmem_guard_depth is 0, which means disabled. 91 * It can be changed by KMEM_GUARD_DEPTH kernel config option. 92 */ 93 94 #include <sys/cdefs.h> 95 __KERNEL_RCSID(0, "$NetBSD: subr_kmem.c,v 1.74 2019/03/26 20:05:18 maxv Exp $"); 96 97 #ifdef _KERNEL_OPT 98 #include "opt_kmem.h" 99 #endif 100 101 #include <sys/param.h> 102 #include <sys/callback.h> 103 #include <sys/kmem.h> 104 #include <sys/pool.h> 105 #include <sys/debug.h> 106 #include <sys/lockdebug.h> 107 #include <sys/cpu.h> 108 #include <sys/asan.h> 109 110 #include <uvm/uvm_extern.h> 111 #include <uvm/uvm_map.h> 112 113 #include <lib/libkern/libkern.h> 114 115 struct kmem_cache_info { 116 size_t kc_size; 117 const char * kc_name; 118 }; 119 120 static const struct kmem_cache_info kmem_cache_sizes[] = { 121 { 8, "kmem-8" }, 122 { 16, "kmem-16" }, 123 { 24, "kmem-24" }, 124 { 32, "kmem-32" }, 125 { 40, "kmem-40" }, 126 { 48, "kmem-48" }, 127 { 56, "kmem-56" }, 128 { 64, "kmem-64" }, 129 { 80, "kmem-80" }, 130 { 96, "kmem-96" }, 131 { 112, "kmem-112" }, 132 { 128, "kmem-128" }, 133 { 160, "kmem-160" }, 134 { 192, "kmem-192" }, 135 { 224, "kmem-224" }, 136 { 256, "kmem-256" }, 137 { 320, "kmem-320" }, 138 { 384, "kmem-384" }, 139 { 448, "kmem-448" }, 140 { 512, "kmem-512" }, 141 { 768, "kmem-768" }, 142 { 1024, "kmem-1024" }, 143 { 0, NULL } 144 }; 145 146 static const struct kmem_cache_info kmem_cache_big_sizes[] = { 147 { 2048, "kmem-2048" }, 148 { 4096, "kmem-4096" }, 149 { 8192, "kmem-8192" }, 150 { 16384, "kmem-16384" }, 151 { 0, NULL } 152 }; 153 154 /* 155 * KMEM_ALIGN is the smallest guaranteed alignment and also the 156 * smallest allocateable quantum. 157 * Every cache size >= CACHE_LINE_SIZE gets CACHE_LINE_SIZE alignment. 158 */ 159 #define KMEM_ALIGN 8 160 #define KMEM_SHIFT 3 161 #define KMEM_MAXSIZE 1024 162 #define KMEM_CACHE_COUNT (KMEM_MAXSIZE >> KMEM_SHIFT) 163 164 static pool_cache_t kmem_cache[KMEM_CACHE_COUNT] __cacheline_aligned; 165 static size_t kmem_cache_maxidx __read_mostly; 166 167 #define KMEM_BIG_ALIGN 2048 168 #define KMEM_BIG_SHIFT 11 169 #define KMEM_BIG_MAXSIZE 16384 170 #define KMEM_CACHE_BIG_COUNT (KMEM_BIG_MAXSIZE >> KMEM_BIG_SHIFT) 171 172 static pool_cache_t kmem_cache_big[KMEM_CACHE_BIG_COUNT] __cacheline_aligned; 173 static size_t kmem_cache_big_maxidx __read_mostly; 174 175 #if defined(DIAGNOSTIC) && defined(_HARDKERNEL) 176 #define KMEM_SIZE 177 #endif 178 179 #if defined(DEBUG) && defined(_HARDKERNEL) 180 #define KMEM_SIZE 181 #define KMEM_GUARD 182 static void *kmem_freecheck; 183 #endif 184 185 #if defined(KMEM_SIZE) 186 struct kmem_header { 187 size_t size; 188 } __aligned(KMEM_ALIGN); 189 #define SIZE_SIZE sizeof(struct kmem_header) 190 static void kmem_size_set(void *, size_t); 191 static void kmem_size_check(void *, size_t); 192 #else 193 #define SIZE_SIZE 0 194 #define kmem_size_set(p, sz) /* nothing */ 195 #define kmem_size_check(p, sz) /* nothing */ 196 #endif 197 198 #if defined(KMEM_GUARD) 199 #ifndef KMEM_GUARD_DEPTH 200 #define KMEM_GUARD_DEPTH 0 201 #endif 202 struct kmem_guard { 203 u_int kg_depth; 204 intptr_t * kg_fifo; 205 u_int kg_rotor; 206 vmem_t * kg_vmem; 207 }; 208 static bool kmem_guard_init(struct kmem_guard *, u_int, vmem_t *); 209 static void *kmem_guard_alloc(struct kmem_guard *, size_t, bool); 210 static void kmem_guard_free(struct kmem_guard *, size_t, void *); 211 int kmem_guard_depth = KMEM_GUARD_DEPTH; 212 static bool kmem_guard_enabled; 213 static struct kmem_guard kmem_guard; 214 #endif /* defined(KMEM_GUARD) */ 215 216 CTASSERT(KM_SLEEP == PR_WAITOK); 217 CTASSERT(KM_NOSLEEP == PR_NOWAIT); 218 219 /* 220 * kmem_intr_alloc: allocate wired memory. 221 */ 222 223 void * 224 kmem_intr_alloc(size_t requested_size, km_flag_t kmflags) 225 { 226 #ifdef KASAN 227 const size_t origsize = requested_size; 228 #endif 229 size_t allocsz, index; 230 size_t size; 231 pool_cache_t pc; 232 uint8_t *p; 233 234 KASSERT(requested_size > 0); 235 236 KASSERT((kmflags & KM_SLEEP) || (kmflags & KM_NOSLEEP)); 237 KASSERT(!(kmflags & KM_SLEEP) || !(kmflags & KM_NOSLEEP)); 238 239 #ifdef KMEM_GUARD 240 if (kmem_guard_enabled) { 241 return kmem_guard_alloc(&kmem_guard, requested_size, 242 (kmflags & KM_SLEEP) != 0); 243 } 244 #endif 245 246 kasan_add_redzone(&requested_size); 247 size = kmem_roundup_size(requested_size); 248 allocsz = size + SIZE_SIZE; 249 250 if ((index = ((allocsz -1) >> KMEM_SHIFT)) 251 < kmem_cache_maxidx) { 252 pc = kmem_cache[index]; 253 } else if ((index = ((allocsz - 1) >> KMEM_BIG_SHIFT)) 254 < kmem_cache_big_maxidx) { 255 pc = kmem_cache_big[index]; 256 } else { 257 int ret = uvm_km_kmem_alloc(kmem_va_arena, 258 (vsize_t)round_page(size), 259 ((kmflags & KM_SLEEP) ? VM_SLEEP : VM_NOSLEEP) 260 | VM_INSTANTFIT, (vmem_addr_t *)&p); 261 if (ret) { 262 return NULL; 263 } 264 FREECHECK_OUT(&kmem_freecheck, p); 265 return p; 266 } 267 268 p = pool_cache_get(pc, kmflags); 269 270 if (__predict_true(p != NULL)) { 271 FREECHECK_OUT(&kmem_freecheck, p); 272 kmem_size_set(p, requested_size); 273 p += SIZE_SIZE; 274 kasan_mark(p, origsize, size); 275 return p; 276 } 277 return p; 278 } 279 280 /* 281 * kmem_intr_zalloc: allocate zeroed wired memory. 282 */ 283 284 void * 285 kmem_intr_zalloc(size_t size, km_flag_t kmflags) 286 { 287 void *p; 288 289 p = kmem_intr_alloc(size, kmflags); 290 if (p != NULL) { 291 memset(p, 0, size); 292 } 293 return p; 294 } 295 296 /* 297 * kmem_intr_free: free wired memory allocated by kmem_alloc. 298 */ 299 300 void 301 kmem_intr_free(void *p, size_t requested_size) 302 { 303 size_t allocsz, index; 304 size_t size; 305 pool_cache_t pc; 306 307 KASSERT(p != NULL); 308 KASSERT(requested_size > 0); 309 310 #ifdef KMEM_GUARD 311 if (kmem_guard_enabled) { 312 kmem_guard_free(&kmem_guard, requested_size, p); 313 return; 314 } 315 #endif 316 317 kasan_add_redzone(&requested_size); 318 size = kmem_roundup_size(requested_size); 319 allocsz = size + SIZE_SIZE; 320 321 if ((index = ((allocsz -1) >> KMEM_SHIFT)) 322 < kmem_cache_maxidx) { 323 pc = kmem_cache[index]; 324 } else if ((index = ((allocsz - 1) >> KMEM_BIG_SHIFT)) 325 < kmem_cache_big_maxidx) { 326 pc = kmem_cache_big[index]; 327 } else { 328 FREECHECK_IN(&kmem_freecheck, p); 329 uvm_km_kmem_free(kmem_va_arena, (vaddr_t)p, 330 round_page(size)); 331 return; 332 } 333 334 kasan_mark(p, size, size); 335 336 p = (uint8_t *)p - SIZE_SIZE; 337 kmem_size_check(p, requested_size); 338 FREECHECK_IN(&kmem_freecheck, p); 339 LOCKDEBUG_MEM_CHECK(p, size); 340 341 pool_cache_put(pc, p); 342 } 343 344 /* ---- kmem API */ 345 346 /* 347 * kmem_alloc: allocate wired memory. 348 * => must not be called from interrupt context. 349 */ 350 351 void * 352 kmem_alloc(size_t size, km_flag_t kmflags) 353 { 354 void *v; 355 356 KASSERTMSG((!cpu_intr_p() && !cpu_softintr_p()), 357 "kmem(9) should not be used from the interrupt context"); 358 v = kmem_intr_alloc(size, kmflags); 359 KASSERT(v || (kmflags & KM_NOSLEEP) != 0); 360 return v; 361 } 362 363 /* 364 * kmem_zalloc: allocate zeroed wired memory. 365 * => must not be called from interrupt context. 366 */ 367 368 void * 369 kmem_zalloc(size_t size, km_flag_t kmflags) 370 { 371 void *v; 372 373 KASSERTMSG((!cpu_intr_p() && !cpu_softintr_p()), 374 "kmem(9) should not be used from the interrupt context"); 375 v = kmem_intr_zalloc(size, kmflags); 376 KASSERT(v || (kmflags & KM_NOSLEEP) != 0); 377 return v; 378 } 379 380 /* 381 * kmem_free: free wired memory allocated by kmem_alloc. 382 * => must not be called from interrupt context. 383 */ 384 385 void 386 kmem_free(void *p, size_t size) 387 { 388 KASSERT(!cpu_intr_p()); 389 KASSERT(!cpu_softintr_p()); 390 kmem_intr_free(p, size); 391 } 392 393 static size_t 394 kmem_create_caches(const struct kmem_cache_info *array, 395 pool_cache_t alloc_table[], size_t maxsize, int shift, int ipl) 396 { 397 size_t maxidx = 0; 398 size_t table_unit = (1 << shift); 399 size_t size = table_unit; 400 int i; 401 402 for (i = 0; array[i].kc_size != 0 ; i++) { 403 const char *name = array[i].kc_name; 404 size_t cache_size = array[i].kc_size; 405 struct pool_allocator *pa; 406 int flags = 0; 407 pool_cache_t pc; 408 size_t align; 409 410 if ((cache_size & (CACHE_LINE_SIZE - 1)) == 0) 411 align = CACHE_LINE_SIZE; 412 else if ((cache_size & (PAGE_SIZE - 1)) == 0) 413 align = PAGE_SIZE; 414 else 415 align = KMEM_ALIGN; 416 417 if (cache_size < CACHE_LINE_SIZE) 418 flags |= PR_NOTOUCH; 419 420 /* check if we reached the requested size */ 421 if (cache_size > maxsize || cache_size > PAGE_SIZE) { 422 break; 423 } 424 if ((cache_size >> shift) > maxidx) { 425 maxidx = cache_size >> shift; 426 } 427 428 if ((cache_size >> shift) > maxidx) { 429 maxidx = cache_size >> shift; 430 } 431 432 pa = &pool_allocator_kmem; 433 pc = pool_cache_init(cache_size, align, 0, flags, 434 name, pa, ipl, NULL, NULL, NULL); 435 436 while (size <= cache_size) { 437 alloc_table[(size - 1) >> shift] = pc; 438 size += table_unit; 439 } 440 } 441 return maxidx; 442 } 443 444 void 445 kmem_init(void) 446 { 447 #ifdef KMEM_GUARD 448 kmem_guard_enabled = kmem_guard_init(&kmem_guard, kmem_guard_depth, 449 kmem_va_arena); 450 #endif 451 kmem_cache_maxidx = kmem_create_caches(kmem_cache_sizes, 452 kmem_cache, KMEM_MAXSIZE, KMEM_SHIFT, IPL_VM); 453 kmem_cache_big_maxidx = kmem_create_caches(kmem_cache_big_sizes, 454 kmem_cache_big, PAGE_SIZE, KMEM_BIG_SHIFT, IPL_VM); 455 } 456 457 size_t 458 kmem_roundup_size(size_t size) 459 { 460 return (size + (KMEM_ALIGN - 1)) & ~(KMEM_ALIGN - 1); 461 } 462 463 /* 464 * Used to dynamically allocate string with kmem accordingly to format. 465 */ 466 char * 467 kmem_asprintf(const char *fmt, ...) 468 { 469 int size __diagused, len; 470 va_list va; 471 char *str; 472 473 va_start(va, fmt); 474 len = vsnprintf(NULL, 0, fmt, va); 475 va_end(va); 476 477 str = kmem_alloc(len + 1, KM_SLEEP); 478 479 va_start(va, fmt); 480 size = vsnprintf(str, len + 1, fmt, va); 481 va_end(va); 482 483 KASSERT(size == len); 484 485 return str; 486 } 487 488 char * 489 kmem_strdupsize(const char *str, size_t *lenp, km_flag_t flags) 490 { 491 size_t len = strlen(str) + 1; 492 char *ptr = kmem_alloc(len, flags); 493 if (ptr == NULL) 494 return NULL; 495 496 if (lenp) 497 *lenp = len; 498 memcpy(ptr, str, len); 499 return ptr; 500 } 501 502 char * 503 kmem_strndup(const char *str, size_t maxlen, km_flag_t flags) 504 { 505 KASSERT(str != NULL); 506 KASSERT(maxlen != 0); 507 508 size_t len = strnlen(str, maxlen); 509 char *ptr = kmem_alloc(len + 1, flags); 510 if (ptr == NULL) 511 return NULL; 512 513 memcpy(ptr, str, len); 514 ptr[len] = '\0'; 515 516 return ptr; 517 } 518 519 void 520 kmem_strfree(char *str) 521 { 522 if (str == NULL) 523 return; 524 525 kmem_free(str, strlen(str) + 1); 526 } 527 528 /* ------------------ DEBUG / DIAGNOSTIC ------------------ */ 529 530 #if defined(KMEM_SIZE) 531 static void 532 kmem_size_set(void *p, size_t sz) 533 { 534 struct kmem_header *hd; 535 hd = (struct kmem_header *)p; 536 hd->size = sz; 537 } 538 539 static void 540 kmem_size_check(void *p, size_t sz) 541 { 542 struct kmem_header *hd; 543 size_t hsz; 544 545 hd = (struct kmem_header *)p; 546 hsz = hd->size; 547 548 if (hsz != sz) { 549 panic("kmem_free(%p, %zu) != allocated size %zu", 550 (const uint8_t *)p + SIZE_SIZE, sz, hsz); 551 } 552 553 hd->size = -1; 554 } 555 #endif /* defined(KMEM_SIZE) */ 556 557 #if defined(KMEM_GUARD) 558 /* 559 * The ultimate memory allocator for debugging, baby. It tries to catch: 560 * 561 * 1. Overflow, in realtime. A guard page sits immediately after the 562 * requested area; a read/write overflow therefore triggers a page 563 * fault. 564 * 2. Invalid pointer/size passed, at free. A kmem_header structure sits 565 * just before the requested area, and holds the allocated size. Any 566 * difference with what is given at free triggers a panic. 567 * 3. Underflow, at free. If an underflow occurs, the kmem header will be 568 * modified, and 2. will trigger a panic. 569 * 4. Use-after-free. When freeing, the memory is unmapped, and depending 570 * on the value of kmem_guard_depth, the kernel will more or less delay 571 * the recycling of that memory. Which means that any ulterior read/write 572 * access to the memory will trigger a page fault, given it hasn't been 573 * recycled yet. 574 */ 575 576 #include <sys/atomic.h> 577 #include <uvm/uvm.h> 578 579 static bool 580 kmem_guard_init(struct kmem_guard *kg, u_int depth, vmem_t *vm) 581 { 582 vaddr_t va; 583 584 /* If not enabled, we have nothing to do. */ 585 if (depth == 0) { 586 return false; 587 } 588 depth = roundup(depth, PAGE_SIZE / sizeof(void *)); 589 KASSERT(depth != 0); 590 591 /* 592 * Allocate fifo. 593 */ 594 va = uvm_km_alloc(kernel_map, depth * sizeof(void *), PAGE_SIZE, 595 UVM_KMF_WIRED | UVM_KMF_ZERO); 596 if (va == 0) { 597 return false; 598 } 599 600 /* 601 * Init object. 602 */ 603 kg->kg_vmem = vm; 604 kg->kg_fifo = (void *)va; 605 kg->kg_depth = depth; 606 kg->kg_rotor = 0; 607 608 printf("kmem_guard(%p): depth %d\n", kg, depth); 609 return true; 610 } 611 612 static void * 613 kmem_guard_alloc(struct kmem_guard *kg, size_t requested_size, bool waitok) 614 { 615 struct vm_page *pg; 616 vm_flag_t flags; 617 vmem_addr_t va; 618 vaddr_t loopva; 619 vsize_t loopsize; 620 size_t size; 621 void **p; 622 623 /* 624 * Compute the size: take the kmem header into account, and add a guard 625 * page at the end. 626 */ 627 size = round_page(requested_size + SIZE_SIZE) + PAGE_SIZE; 628 629 /* Allocate pages of kernel VA, but do not map anything in yet. */ 630 flags = VM_BESTFIT | (waitok ? VM_SLEEP : VM_NOSLEEP); 631 if (vmem_alloc(kg->kg_vmem, size, flags, &va) != 0) { 632 return NULL; 633 } 634 635 loopva = va; 636 loopsize = size - PAGE_SIZE; 637 638 while (loopsize) { 639 pg = uvm_pagealloc(NULL, loopva, NULL, 0); 640 if (__predict_false(pg == NULL)) { 641 if (waitok) { 642 uvm_wait("kmem_guard"); 643 continue; 644 } else { 645 uvm_km_pgremove_intrsafe(kernel_map, va, 646 va + size); 647 vmem_free(kg->kg_vmem, va, size); 648 return NULL; 649 } 650 } 651 652 pg->flags &= ~PG_BUSY; /* new page */ 653 UVM_PAGE_OWN(pg, NULL); 654 pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg), 655 VM_PROT_READ|VM_PROT_WRITE, PMAP_KMPAGE); 656 657 loopva += PAGE_SIZE; 658 loopsize -= PAGE_SIZE; 659 } 660 661 pmap_update(pmap_kernel()); 662 663 /* 664 * Offset the returned pointer so that the unmapped guard page sits 665 * immediately after the returned object. 666 */ 667 p = (void **)((va + (size - PAGE_SIZE) - requested_size) & ~(uintptr_t)ALIGNBYTES); 668 kmem_size_set((uint8_t *)p - SIZE_SIZE, requested_size); 669 return (void *)p; 670 } 671 672 static void 673 kmem_guard_free(struct kmem_guard *kg, size_t requested_size, void *p) 674 { 675 vaddr_t va; 676 u_int rotor; 677 size_t size; 678 uint8_t *ptr; 679 680 ptr = (uint8_t *)p - SIZE_SIZE; 681 kmem_size_check(ptr, requested_size); 682 va = trunc_page((vaddr_t)ptr); 683 size = round_page(requested_size + SIZE_SIZE) + PAGE_SIZE; 684 685 KASSERT(pmap_extract(pmap_kernel(), va, NULL)); 686 KASSERT(!pmap_extract(pmap_kernel(), va + (size - PAGE_SIZE), NULL)); 687 688 /* 689 * Unmap and free the pages. The last one is never allocated. 690 */ 691 uvm_km_pgremove_intrsafe(kernel_map, va, va + size); 692 pmap_update(pmap_kernel()); 693 694 #if 0 695 /* 696 * XXX: Here, we need to atomically register the va and its size in the 697 * fifo. 698 */ 699 700 /* 701 * Put the VA allocation into the list and swap an old one out to free. 702 * This behaves mostly like a fifo. 703 */ 704 rotor = atomic_inc_uint_nv(&kg->kg_rotor) % kg->kg_depth; 705 va = (vaddr_t)atomic_swap_ptr(&kg->kg_fifo[rotor], (void *)va); 706 if (va != 0) { 707 vmem_free(kg->kg_vmem, va, size); 708 } 709 #else 710 (void)rotor; 711 vmem_free(kg->kg_vmem, va, size); 712 #endif 713 } 714 715 #endif /* defined(KMEM_GUARD) */ 716
Indexes created Sun Sep 21 20:09:37 GMT 2025