1 /* $NetBSD: subr_kmem.c,v 1.65 2017/11/09 23:20:12 riastradh 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 * KMEM_REDZONE: detect overrun bugs. 70 * Add a 2-byte pattern (allocate one more memory chunk if needed) at the 71 * end of each allocated buffer. Check this pattern on kmem_free. 72 * 73 * These options are enabled on DIAGNOSTIC. 74 * 75 * |CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK|CHUNK| 76 * +-----+-----+-----+-----+-----+-----+-----+-----+-----+---+-+--+--+ 77 * |/////| | | | | | | | | |*|**|UU| 78 * |/HSZ/| | | | | | | | | |*|**|UU| 79 * |/////| | | | | | | | | |*|**|UU| 80 * +-----+-----+-----+-----+-----+-----+-----+-----+-----+---+-+--+--+ 81 * |Size | Buffer usable by the caller (requested size) |RedZ|Unused\ 82 */ 83 84 /* 85 * KMEM_POISON: detect modify-after-free bugs. 86 * Fill freed (in the sense of kmem_free) memory with a garbage pattern. 87 * Check the pattern on allocation. 88 * 89 * KMEM_GUARD 90 * A kernel with "option DEBUG" has "kmem_guard" debugging feature compiled 91 * in. See the comment below for what kind of bugs it tries to detect. Even 92 * if compiled in, it's disabled by default because it's very expensive. 93 * You can enable it on boot by: 94 * boot -d 95 * db> w kmem_guard_depth 0t30000 96 * db> c 97 * 98 * The default value of kmem_guard_depth is 0, which means disabled. 99 * It can be changed by KMEM_GUARD_DEPTH kernel config option. 100 */ 101 102 #include <sys/cdefs.h> 103 __KERNEL_RCSID(0, "$NetBSD: subr_kmem.c,v 1.65 2017/11/09 23:20:12 riastradh Exp $"); 104 105 #ifdef _KERNEL_OPT 106 #include "opt_kmem.h" 107 #endif 108 109 #include <sys/param.h> 110 #include <sys/callback.h> 111 #include <sys/kmem.h> 112 #include <sys/pool.h> 113 #include <sys/debug.h> 114 #include <sys/lockdebug.h> 115 #include <sys/cpu.h> 116 117 #include <uvm/uvm_extern.h> 118 #include <uvm/uvm_map.h> 119 120 #include <lib/libkern/libkern.h> 121 122 struct kmem_cache_info { 123 size_t kc_size; 124 const char * kc_name; 125 }; 126 127 static const struct kmem_cache_info kmem_cache_sizes[] = { 128 { 8, "kmem-8" }, 129 { 16, "kmem-16" }, 130 { 24, "kmem-24" }, 131 { 32, "kmem-32" }, 132 { 40, "kmem-40" }, 133 { 48, "kmem-48" }, 134 { 56, "kmem-56" }, 135 { 64, "kmem-64" }, 136 { 80, "kmem-80" }, 137 { 96, "kmem-96" }, 138 { 112, "kmem-112" }, 139 { 128, "kmem-128" }, 140 { 160, "kmem-160" }, 141 { 192, "kmem-192" }, 142 { 224, "kmem-224" }, 143 { 256, "kmem-256" }, 144 { 320, "kmem-320" }, 145 { 384, "kmem-384" }, 146 { 448, "kmem-448" }, 147 { 512, "kmem-512" }, 148 { 768, "kmem-768" }, 149 { 1024, "kmem-1024" }, 150 { 0, NULL } 151 }; 152 153 static const struct kmem_cache_info kmem_cache_big_sizes[] = { 154 { 2048, "kmem-2048" }, 155 { 4096, "kmem-4096" }, 156 { 8192, "kmem-8192" }, 157 { 16384, "kmem-16384" }, 158 { 0, NULL } 159 }; 160 161 /* 162 * KMEM_ALIGN is the smallest guaranteed alignment and also the 163 * smallest allocateable quantum. 164 * Every cache size >= CACHE_LINE_SIZE gets CACHE_LINE_SIZE alignment. 165 */ 166 #define KMEM_ALIGN 8 167 #define KMEM_SHIFT 3 168 #define KMEM_MAXSIZE 1024 169 #define KMEM_CACHE_COUNT (KMEM_MAXSIZE >> KMEM_SHIFT) 170 171 static pool_cache_t kmem_cache[KMEM_CACHE_COUNT] __cacheline_aligned; 172 static size_t kmem_cache_maxidx __read_mostly; 173 174 #define KMEM_BIG_ALIGN 2048 175 #define KMEM_BIG_SHIFT 11 176 #define KMEM_BIG_MAXSIZE 16384 177 #define KMEM_CACHE_BIG_COUNT (KMEM_BIG_MAXSIZE >> KMEM_BIG_SHIFT) 178 179 static pool_cache_t kmem_cache_big[KMEM_CACHE_BIG_COUNT] __cacheline_aligned; 180 static size_t kmem_cache_big_maxidx __read_mostly; 181 182 #if defined(DIAGNOSTIC) && defined(_HARDKERNEL) 183 #define KMEM_SIZE 184 #define KMEM_REDZONE 185 #endif /* defined(DIAGNOSTIC) */ 186 187 #if defined(DEBUG) && defined(_HARDKERNEL) 188 #define KMEM_SIZE 189 #define KMEM_POISON 190 #define KMEM_GUARD 191 static void *kmem_freecheck; 192 #endif /* defined(DEBUG) */ 193 194 #if defined(KMEM_POISON) 195 static int kmem_poison_ctor(void *, void *, int); 196 static void kmem_poison_fill(void *, size_t); 197 static void kmem_poison_check(void *, size_t); 198 #else /* defined(KMEM_POISON) */ 199 #define kmem_poison_fill(p, sz) /* nothing */ 200 #define kmem_poison_check(p, sz) /* nothing */ 201 #endif /* defined(KMEM_POISON) */ 202 203 #if defined(KMEM_REDZONE) 204 #define REDZONE_SIZE 2 205 static void kmem_redzone_fill(void *, size_t); 206 static void kmem_redzone_check(void *, size_t); 207 #else /* defined(KMEM_REDZONE) */ 208 #define REDZONE_SIZE 0 209 #define kmem_redzone_fill(p, sz) /* nothing */ 210 #define kmem_redzone_check(p, sz) /* nothing */ 211 #endif /* defined(KMEM_REDZONE) */ 212 213 #if defined(KMEM_SIZE) 214 struct kmem_header { 215 size_t size; 216 } __aligned(KMEM_ALIGN); 217 #define SIZE_SIZE sizeof(struct kmem_header) 218 static void kmem_size_set(void *, size_t); 219 static void kmem_size_check(void *, size_t); 220 #else 221 #define SIZE_SIZE 0 222 #define kmem_size_set(p, sz) /* nothing */ 223 #define kmem_size_check(p, sz) /* nothing */ 224 #endif 225 226 #if defined(KMEM_GUARD) 227 #ifndef KMEM_GUARD_DEPTH 228 #define KMEM_GUARD_DEPTH 0 229 #endif 230 struct kmem_guard { 231 u_int kg_depth; 232 intptr_t * kg_fifo; 233 u_int kg_rotor; 234 vmem_t * kg_vmem; 235 }; 236 237 static bool kmem_guard_init(struct kmem_guard *, u_int, vmem_t *); 238 static void *kmem_guard_alloc(struct kmem_guard *, size_t, bool); 239 static void kmem_guard_free(struct kmem_guard *, size_t, void *); 240 241 int kmem_guard_depth = KMEM_GUARD_DEPTH; 242 static bool kmem_guard_enabled; 243 static struct kmem_guard kmem_guard; 244 #endif /* defined(KMEM_GUARD) */ 245 246 CTASSERT(KM_SLEEP == PR_WAITOK); 247 CTASSERT(KM_NOSLEEP == PR_NOWAIT); 248 249 /* 250 * kmem_intr_alloc: allocate wired memory. 251 */ 252 253 void * 254 kmem_intr_alloc(size_t requested_size, km_flag_t kmflags) 255 { 256 size_t allocsz, index; 257 size_t size; 258 pool_cache_t pc; 259 uint8_t *p; 260 261 KASSERT(requested_size > 0); 262 263 KASSERT((kmflags & KM_SLEEP) || (kmflags & KM_NOSLEEP)); 264 KASSERT(!(kmflags & KM_SLEEP) || !(kmflags & KM_NOSLEEP)); 265 266 #ifdef KMEM_GUARD 267 if (kmem_guard_enabled) { 268 return kmem_guard_alloc(&kmem_guard, requested_size, 269 (kmflags & KM_SLEEP) != 0); 270 } 271 #endif 272 size = kmem_roundup_size(requested_size); 273 allocsz = size + SIZE_SIZE; 274 275 #ifdef KMEM_REDZONE 276 if (size - requested_size < REDZONE_SIZE) { 277 /* If there isn't enough space in the padding, allocate 278 * one more memory chunk for the red zone. */ 279 allocsz += kmem_roundup_size(REDZONE_SIZE); 280 } 281 #endif 282 283 if ((index = ((allocsz -1) >> KMEM_SHIFT)) 284 < kmem_cache_maxidx) { 285 pc = kmem_cache[index]; 286 } else if ((index = ((allocsz - 1) >> KMEM_BIG_SHIFT)) 287 < kmem_cache_big_maxidx) { 288 pc = kmem_cache_big[index]; 289 } else { 290 int ret = uvm_km_kmem_alloc(kmem_va_arena, 291 (vsize_t)round_page(size), 292 ((kmflags & KM_SLEEP) ? VM_SLEEP : VM_NOSLEEP) 293 | VM_INSTANTFIT, (vmem_addr_t *)&p); 294 if (ret) { 295 return NULL; 296 } 297 FREECHECK_OUT(&kmem_freecheck, p); 298 return p; 299 } 300 301 p = pool_cache_get(pc, kmflags); 302 303 if (__predict_true(p != NULL)) { 304 kmem_poison_check(p, allocsz); 305 FREECHECK_OUT(&kmem_freecheck, p); 306 kmem_size_set(p, requested_size); 307 kmem_redzone_fill(p, requested_size + SIZE_SIZE); 308 309 return p + SIZE_SIZE; 310 } 311 return p; 312 } 313 314 /* 315 * kmem_intr_zalloc: allocate zeroed wired memory. 316 */ 317 318 void * 319 kmem_intr_zalloc(size_t size, km_flag_t kmflags) 320 { 321 void *p; 322 323 p = kmem_intr_alloc(size, kmflags); 324 if (p != NULL) { 325 memset(p, 0, size); 326 } 327 return p; 328 } 329 330 /* 331 * kmem_intr_free: free wired memory allocated by kmem_alloc. 332 */ 333 334 void 335 kmem_intr_free(void *p, size_t requested_size) 336 { 337 size_t allocsz, index; 338 size_t size; 339 pool_cache_t pc; 340 341 KASSERT(p != NULL); 342 KASSERT(requested_size > 0); 343 344 #ifdef KMEM_GUARD 345 if (kmem_guard_enabled) { 346 kmem_guard_free(&kmem_guard, requested_size, p); 347 return; 348 } 349 #endif 350 351 size = kmem_roundup_size(requested_size); 352 allocsz = size + SIZE_SIZE; 353 354 #ifdef KMEM_REDZONE 355 if (size - requested_size < REDZONE_SIZE) { 356 allocsz += kmem_roundup_size(REDZONE_SIZE); 357 } 358 #endif 359 360 if ((index = ((allocsz -1) >> KMEM_SHIFT)) 361 < kmem_cache_maxidx) { 362 pc = kmem_cache[index]; 363 } else if ((index = ((allocsz - 1) >> KMEM_BIG_SHIFT)) 364 < kmem_cache_big_maxidx) { 365 pc = kmem_cache_big[index]; 366 } else { 367 FREECHECK_IN(&kmem_freecheck, p); 368 uvm_km_kmem_free(kmem_va_arena, (vaddr_t)p, 369 round_page(size)); 370 return; 371 } 372 373 p = (uint8_t *)p - SIZE_SIZE; 374 kmem_size_check(p, requested_size); 375 kmem_redzone_check(p, requested_size + SIZE_SIZE); 376 FREECHECK_IN(&kmem_freecheck, p); 377 LOCKDEBUG_MEM_CHECK(p, size); 378 kmem_poison_fill(p, allocsz); 379 380 pool_cache_put(pc, p); 381 } 382 383 /* ---- kmem API */ 384 385 /* 386 * kmem_alloc: allocate wired memory. 387 * => must not be called from interrupt context. 388 */ 389 390 void * 391 kmem_alloc(size_t size, km_flag_t kmflags) 392 { 393 void *v; 394 395 KASSERTMSG((!cpu_intr_p() && !cpu_softintr_p()), 396 "kmem(9) should not be used from the interrupt context"); 397 v = kmem_intr_alloc(size, kmflags); 398 KASSERT(v || (kmflags & KM_NOSLEEP) != 0); 399 return v; 400 } 401 402 /* 403 * kmem_zalloc: allocate zeroed wired memory. 404 * => must not be called from interrupt context. 405 */ 406 407 void * 408 kmem_zalloc(size_t size, km_flag_t kmflags) 409 { 410 void *v; 411 412 KASSERTMSG((!cpu_intr_p() && !cpu_softintr_p()), 413 "kmem(9) should not be used from the interrupt context"); 414 v = kmem_intr_zalloc(size, kmflags); 415 KASSERT(v || (kmflags & KM_NOSLEEP) != 0); 416 return v; 417 } 418 419 /* 420 * kmem_free: free wired memory allocated by kmem_alloc. 421 * => must not be called from interrupt context. 422 */ 423 424 void 425 kmem_free(void *p, size_t size) 426 { 427 KASSERT(!cpu_intr_p()); 428 KASSERT(!cpu_softintr_p()); 429 kmem_intr_free(p, size); 430 } 431 432 static size_t 433 kmem_create_caches(const struct kmem_cache_info *array, 434 pool_cache_t alloc_table[], size_t maxsize, int shift, int ipl) 435 { 436 size_t maxidx = 0; 437 size_t table_unit = (1 << shift); 438 size_t size = table_unit; 439 int i; 440 441 for (i = 0; array[i].kc_size != 0 ; i++) { 442 const char *name = array[i].kc_name; 443 size_t cache_size = array[i].kc_size; 444 struct pool_allocator *pa; 445 int flags = PR_NOALIGN; 446 pool_cache_t pc; 447 size_t align; 448 449 if ((cache_size & (CACHE_LINE_SIZE - 1)) == 0) 450 align = CACHE_LINE_SIZE; 451 else if ((cache_size & (PAGE_SIZE - 1)) == 0) 452 align = PAGE_SIZE; 453 else 454 align = KMEM_ALIGN; 455 456 if (cache_size < CACHE_LINE_SIZE) 457 flags |= PR_NOTOUCH; 458 459 /* check if we reached the requested size */ 460 if (cache_size > maxsize || cache_size > PAGE_SIZE) { 461 break; 462 } 463 if ((cache_size >> shift) > maxidx) { 464 maxidx = cache_size >> shift; 465 } 466 467 if ((cache_size >> shift) > maxidx) { 468 maxidx = cache_size >> shift; 469 } 470 471 pa = &pool_allocator_kmem; 472 #if defined(KMEM_POISON) 473 pc = pool_cache_init(cache_size, align, 0, flags, 474 name, pa, ipl, kmem_poison_ctor, 475 NULL, (void *)cache_size); 476 #else /* defined(KMEM_POISON) */ 477 pc = pool_cache_init(cache_size, align, 0, flags, 478 name, pa, ipl, NULL, NULL, NULL); 479 #endif /* defined(KMEM_POISON) */ 480 481 while (size <= cache_size) { 482 alloc_table[(size - 1) >> shift] = pc; 483 size += table_unit; 484 } 485 } 486 return maxidx; 487 } 488 489 void 490 kmem_init(void) 491 { 492 #ifdef KMEM_GUARD 493 kmem_guard_enabled = kmem_guard_init(&kmem_guard, kmem_guard_depth, 494 kmem_va_arena); 495 #endif 496 kmem_cache_maxidx = kmem_create_caches(kmem_cache_sizes, 497 kmem_cache, KMEM_MAXSIZE, KMEM_SHIFT, IPL_VM); 498 kmem_cache_big_maxidx = kmem_create_caches(kmem_cache_big_sizes, 499 kmem_cache_big, PAGE_SIZE, KMEM_BIG_SHIFT, IPL_VM); 500 } 501 502 size_t 503 kmem_roundup_size(size_t size) 504 { 505 return (size + (KMEM_ALIGN - 1)) & ~(KMEM_ALIGN - 1); 506 } 507 508 /* 509 * Used to dynamically allocate string with kmem accordingly to format. 510 */ 511 char * 512 kmem_asprintf(const char *fmt, ...) 513 { 514 int size __diagused, len; 515 va_list va; 516 char *str; 517 518 va_start(va, fmt); 519 len = vsnprintf(NULL, 0, fmt, va); 520 va_end(va); 521 522 str = kmem_alloc(len + 1, KM_SLEEP); 523 524 va_start(va, fmt); 525 size = vsnprintf(str, len + 1, fmt, va); 526 va_end(va); 527 528 KASSERT(size == len); 529 530 return str; 531 } 532 533 char * 534 kmem_strdupsize(const char *str, size_t *lenp, km_flag_t flags) 535 { 536 size_t len = strlen(str) + 1; 537 char *ptr = kmem_alloc(len, flags); 538 if (ptr == NULL) 539 return NULL; 540 541 if (lenp) 542 *lenp = len; 543 memcpy(ptr, str, len); 544 return ptr; 545 } 546 547 void 548 kmem_strfree(char *str) 549 { 550 if (str == NULL) 551 return; 552 553 kmem_free(str, strlen(str) + 1); 554 } 555 556 /* ------------------ DEBUG / DIAGNOSTIC ------------------ */ 557 558 #if defined(KMEM_POISON) || defined(KMEM_REDZONE) 559 #if defined(_LP64) 560 #define PRIME 0x9e37fffffffc0000UL 561 #else /* defined(_LP64) */ 562 #define PRIME 0x9e3779b1 563 #endif /* defined(_LP64) */ 564 565 static inline uint8_t 566 kmem_pattern_generate(const void *p) 567 { 568 return (uint8_t)(((uintptr_t)p) * PRIME 569 >> ((sizeof(uintptr_t) - sizeof(uint8_t))) * CHAR_BIT); 570 } 571 #endif /* defined(KMEM_POISON) || defined(KMEM_REDZONE) */ 572 573 #if defined(KMEM_POISON) 574 static int 575 kmem_poison_ctor(void *arg, void *obj, int flag) 576 { 577 size_t sz = (size_t)arg; 578 579 kmem_poison_fill(obj, sz); 580 581 return 0; 582 } 583 584 static void 585 kmem_poison_fill(void *p, size_t sz) 586 { 587 uint8_t *cp; 588 const uint8_t *ep; 589 590 cp = p; 591 ep = cp + sz; 592 while (cp < ep) { 593 *cp = kmem_pattern_generate(cp); 594 cp++; 595 } 596 } 597 598 static void 599 kmem_poison_check(void *p, size_t sz) 600 { 601 uint8_t *cp; 602 const uint8_t *ep; 603 604 cp = p; 605 ep = cp + sz; 606 while (cp < ep) { 607 const uint8_t expected = kmem_pattern_generate(cp); 608 609 if (*cp != expected) { 610 panic("%s: %p: 0x%02x != 0x%02x\n", 611 __func__, cp, *cp, expected); 612 } 613 cp++; 614 } 615 } 616 #endif /* defined(KMEM_POISON) */ 617 618 #if defined(KMEM_SIZE) 619 static void 620 kmem_size_set(void *p, size_t sz) 621 { 622 struct kmem_header *hd; 623 hd = (struct kmem_header *)p; 624 hd->size = sz; 625 } 626 627 static void 628 kmem_size_check(void *p, size_t sz) 629 { 630 struct kmem_header *hd; 631 size_t hsz; 632 633 hd = (struct kmem_header *)p; 634 hsz = hd->size; 635 636 if (hsz != sz) { 637 panic("kmem_free(%p, %zu) != allocated size %zu", 638 (const uint8_t *)p + SIZE_SIZE, sz, hsz); 639 } 640 } 641 #endif /* defined(KMEM_SIZE) */ 642 643 #if defined(KMEM_REDZONE) 644 #define STATIC_BYTE 0xFE 645 CTASSERT(REDZONE_SIZE > 1); 646 static void 647 kmem_redzone_fill(void *p, size_t sz) 648 { 649 uint8_t *cp, pat; 650 const uint8_t *ep; 651 652 cp = (uint8_t *)p + sz; 653 ep = cp + REDZONE_SIZE; 654 655 /* 656 * We really don't want the first byte of the red zone to be '\0'; 657 * an off-by-one in a string may not be properly detected. 658 */ 659 pat = kmem_pattern_generate(cp); 660 *cp = (pat == '\0') ? STATIC_BYTE: pat; 661 cp++; 662 663 while (cp < ep) { 664 *cp = kmem_pattern_generate(cp); 665 cp++; 666 } 667 } 668 669 static void 670 kmem_redzone_check(void *p, size_t sz) 671 { 672 uint8_t *cp, pat, expected; 673 const uint8_t *ep; 674 675 cp = (uint8_t *)p + sz; 676 ep = cp + REDZONE_SIZE; 677 678 pat = kmem_pattern_generate(cp); 679 expected = (pat == '\0') ? STATIC_BYTE: pat; 680 if (expected != *cp) { 681 panic("%s: %p: 0x%02x != 0x%02x\n", 682 __func__, cp, *cp, expected); 683 } 684 cp++; 685 686 while (cp < ep) { 687 expected = kmem_pattern_generate(cp); 688 if (*cp != expected) { 689 panic("%s: %p: 0x%02x != 0x%02x\n", 690 __func__, cp, *cp, expected); 691 } 692 cp++; 693 } 694 } 695 #endif /* defined(KMEM_REDZONE) */ 696 697 698 #if defined(KMEM_GUARD) 699 /* 700 * The ultimate memory allocator for debugging, baby. It tries to catch: 701 * 702 * 1. Overflow, in realtime. A guard page sits immediately after the 703 * requested area; a read/write overflow therefore triggers a page 704 * fault. 705 * 2. Invalid pointer/size passed, at free. A kmem_header structure sits 706 * just before the requested area, and holds the allocated size. Any 707 * difference with what is given at free triggers a panic. 708 * 3. Underflow, at free. If an underflow occurs, the kmem header will be 709 * modified, and 2. will trigger a panic. 710 * 4. Use-after-free. When freeing, the memory is unmapped, and depending 711 * on the value of kmem_guard_depth, the kernel will more or less delay 712 * the recycling of that memory. Which means that any ulterior read/write 713 * access to the memory will trigger a page fault, given it hasn't been 714 * recycled yet. 715 */ 716 717 #include <sys/atomic.h> 718 #include <uvm/uvm.h> 719 720 static bool 721 kmem_guard_init(struct kmem_guard *kg, u_int depth, vmem_t *vm) 722 { 723 vaddr_t va; 724 725 /* If not enabled, we have nothing to do. */ 726 if (depth == 0) { 727 return false; 728 } 729 depth = roundup(depth, PAGE_SIZE / sizeof(void *)); 730 KASSERT(depth != 0); 731 732 /* 733 * Allocate fifo. 734 */ 735 va = uvm_km_alloc(kernel_map, depth * sizeof(void *), PAGE_SIZE, 736 UVM_KMF_WIRED | UVM_KMF_ZERO); 737 if (va == 0) { 738 return false; 739 } 740 741 /* 742 * Init object. 743 */ 744 kg->kg_vmem = vm; 745 kg->kg_fifo = (void *)va; 746 kg->kg_depth = depth; 747 kg->kg_rotor = 0; 748 749 printf("kmem_guard(%p): depth %d\n", kg, depth); 750 return true; 751 } 752 753 static void * 754 kmem_guard_alloc(struct kmem_guard *kg, size_t requested_size, bool waitok) 755 { 756 struct vm_page *pg; 757 vm_flag_t flags; 758 vmem_addr_t va; 759 vaddr_t loopva; 760 vsize_t loopsize; 761 size_t size; 762 void **p; 763 764 /* 765 * Compute the size: take the kmem header into account, and add a guard 766 * page at the end. 767 */ 768 size = round_page(requested_size + SIZE_SIZE) + PAGE_SIZE; 769 770 /* Allocate pages of kernel VA, but do not map anything in yet. */ 771 flags = VM_BESTFIT | (waitok ? VM_SLEEP : VM_NOSLEEP); 772 if (vmem_alloc(kg->kg_vmem, size, flags, &va) != 0) { 773 return NULL; 774 } 775 776 loopva = va; 777 loopsize = size - PAGE_SIZE; 778 779 while (loopsize) { 780 pg = uvm_pagealloc(NULL, loopva, NULL, 0); 781 if (__predict_false(pg == NULL)) { 782 if (waitok) { 783 uvm_wait("kmem_guard"); 784 continue; 785 } else { 786 uvm_km_pgremove_intrsafe(kernel_map, va, 787 va + size); 788 vmem_free(kg->kg_vmem, va, size); 789 return NULL; 790 } 791 } 792 793 pg->flags &= ~PG_BUSY; /* new page */ 794 UVM_PAGE_OWN(pg, NULL); 795 pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg), 796 VM_PROT_READ|VM_PROT_WRITE, PMAP_KMPAGE); 797 798 loopva += PAGE_SIZE; 799 loopsize -= PAGE_SIZE; 800 } 801 802 pmap_update(pmap_kernel()); 803 804 /* 805 * Offset the returned pointer so that the unmapped guard page sits 806 * immediately after the returned object. 807 */ 808 p = (void **)((va + (size - PAGE_SIZE) - requested_size) & ~(uintptr_t)ALIGNBYTES); 809 kmem_size_set((uint8_t *)p - SIZE_SIZE, requested_size); 810 return (void *)p; 811 } 812 813 static void 814 kmem_guard_free(struct kmem_guard *kg, size_t requested_size, void *p) 815 { 816 vaddr_t va; 817 u_int rotor; 818 size_t size; 819 uint8_t *ptr; 820 821 ptr = (uint8_t *)p - SIZE_SIZE; 822 kmem_size_check(ptr, requested_size); 823 va = trunc_page((vaddr_t)ptr); 824 size = round_page(requested_size + SIZE_SIZE) + PAGE_SIZE; 825 826 KASSERT(pmap_extract(pmap_kernel(), va, NULL)); 827 KASSERT(!pmap_extract(pmap_kernel(), va + (size - PAGE_SIZE), NULL)); 828 829 /* 830 * Unmap and free the pages. The last one is never allocated. 831 */ 832 uvm_km_pgremove_intrsafe(kernel_map, va, va + size); 833 pmap_update(pmap_kernel()); 834 835 #if 0 836 /* 837 * XXX: Here, we need to atomically register the va and its size in the 838 * fifo. 839 */ 840 841 /* 842 * Put the VA allocation into the list and swap an old one out to free. 843 * This behaves mostly like a fifo. 844 */ 845 rotor = atomic_inc_uint_nv(&kg->kg_rotor) % kg->kg_depth; 846 va = (vaddr_t)atomic_swap_ptr(&kg->kg_fifo[rotor], (void *)va); 847 if (va != 0) { 848 vmem_free(kg->kg_vmem, va, size); 849 } 850 #else 851 (void)rotor; 852 vmem_free(kg->kg_vmem, va, size); 853 #endif 854 } 855 856 #endif /* defined(KMEM_GUARD) */ 857