1 /* $NetBSD: pmap_segtab.c,v 1.23 2020/08/22 15:34:51 skrll Exp $ */ 2 3 /*- 4 * Copyright (c) 1998, 2001 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center and by Chris G. Demetriou. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * Copyright (c) 1992, 1993 35 * The Regents of the University of California. All rights reserved. 36 * 37 * This code is derived from software contributed to Berkeley by 38 * the Systems Programming Group of the University of Utah Computer 39 * Science Department and Ralph Campbell. 40 * 41 * Redistribution and use in source and binary forms, with or without 42 * modification, are permitted provided that the following conditions 43 * are met: 44 * 1. Redistributions of source code must retain the above copyright 45 * notice, this list of conditions and the following disclaimer. 46 * 2. Redistributions in binary form must reproduce the above copyright 47 * notice, this list of conditions and the following disclaimer in the 48 * documentation and/or other materials provided with the distribution. 49 * 3. Neither the name of the University nor the names of its contributors 50 * may be used to endorse or promote products derived from this software 51 * without specific prior written permission. 52 * 53 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 54 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 55 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 56 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 57 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 58 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 59 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 60 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 61 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 62 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 63 * SUCH DAMAGE. 64 * 65 * @(#)pmap.c 8.4 (Berkeley) 1/26/94 66 */ 67 68 #include <sys/cdefs.h> 69 70 __KERNEL_RCSID(0, "$NetBSD: pmap_segtab.c,v 1.23 2020/08/22 15:34:51 skrll Exp $"); 71 72 /* 73 * Manages physical address maps. 74 * 75 * In addition to hardware address maps, this 76 * module is called upon to provide software-use-only 77 * maps which may or may not be stored in the same 78 * form as hardware maps. These pseudo-maps are 79 * used to store intermediate results from copy 80 * operations to and from address spaces. 81 * 82 * Since the information managed by this module is 83 * also stored by the logical address mapping module, 84 * this module may throw away valid virtual-to-physical 85 * mappings at almost any time. However, invalidations 86 * of virtual-to-physical mappings must be done as 87 * requested. 88 * 89 * In order to cope with hardware architectures which 90 * make virtual-to-physical map invalidates expensive, 91 * this module may delay invalidate or reduced protection 92 * operations until such time as they are actually 93 * necessary. This module is given full information as 94 * to which processors are currently using which maps, 95 * and to when physical maps must be made correct. 96 */ 97 98 #define __PMAP_PRIVATE 99 100 #include "opt_multiprocessor.h" 101 102 #include <sys/param.h> 103 104 #include <sys/atomic.h> 105 #include <sys/mutex.h> 106 #include <sys/proc.h> 107 #include <sys/systm.h> 108 109 #include <uvm/uvm.h> 110 111 CTASSERT(NBPG >= sizeof(pmap_segtab_t)); 112 113 struct pmap_segtab_info { 114 pmap_segtab_t *free_segtab; /* free list kept locally */ 115 #ifdef DEBUG 116 uint32_t nget_segtab; 117 uint32_t nput_segtab; 118 uint32_t npage_segtab; 119 #define SEGTAB_ADD(n, v) (pmap_segtab_info.n ## _segtab += (v)) 120 #else 121 #define SEGTAB_ADD(n, v) ((void) 0) 122 #endif 123 #ifdef PMAP_PTP_CACHE 124 struct pgflist ptp_pgflist; /* Keep a list of idle page tables. */ 125 #endif 126 } pmap_segtab_info = { 127 #ifdef PMAP_PTP_CACHE 128 .ptp_pgflist = LIST_HEAD_INITIALIZER(pmap_segtab_info.ptp_pgflist), 129 #endif 130 }; 131 132 kmutex_t pmap_segtab_lock __cacheline_aligned; 133 134 /* 135 * Check that a seg_tab[] array is empty. 136 * 137 * This is used when allocating or freeing a pmap_segtab_t. The stp 138 * should be unused -- meaning, none of the seg_tab[] pointers are 139 * not NULL, as it transitions from either freshly allocated segtab from 140 * pmap pool, an unused allocated page segtab alloc from the SMP case, 141 * where two CPUs attempt to allocate the same underlying segtab, the 142 * release of a segtab entry to the freelist, or for SMP, where reserve 143 * also frees a freshly allocated but unused entry. 144 */ 145 static void 146 pmap_check_stp(pmap_segtab_t *stp, const char *caller, const char *why) 147 { 148 #ifdef DEBUG 149 for (size_t i = 0; i < PMAP_SEGTABSIZE; i++) { 150 if (stp->seg_tab[i] != NULL) { 151 #define DEBUG_NOISY 152 #ifdef DEBUG_NOISY 153 UVMHIST_FUNC(__func__); 154 UVMHIST_CALLARGS(pmapsegtabhist, "stp=%#jx", 155 (uintptr_t)stp, 0, 0, 0); 156 for (size_t j = i; j < PMAP_SEGTABSIZE; j++) 157 if (stp->seg_tab[j] != NULL) 158 printf("%s: stp->seg_tab[%zu] = %p\n", 159 caller, j, stp->seg_tab[j]); 160 #endif 161 panic("%s: pm_segtab.seg_tab[%zu] != 0 (%p): %s", 162 caller, i, stp->seg_tab[i], why); 163 } 164 } 165 #endif 166 } 167 168 /* 169 * Check that an array of ptes is actually zero. 170 */ 171 static void 172 pmap_check_ptes(pt_entry_t *pte, const char *caller) 173 { 174 /* 175 * All pte arrays should be page aligned. 176 */ 177 if (((uintptr_t)pte & PAGE_MASK) != 0) { 178 panic("%s: pte entry at %p not page aligned", caller, pte); 179 } 180 181 #ifdef DEBUG 182 for (size_t i = 0; i < NPTEPG; i++) 183 if (pte[i] != 0) { 184 #ifdef DEBUG_NOISY 185 UVMHIST_FUNC(__func__); 186 UVMHIST_CALLARGS(pmapsegtabhist, "pte=%#jx", 187 (uintptr_t)pte, 0, 0, 0); 188 for (size_t j = i + 1; j < NPTEPG; j++) 189 if (pte[j] != 0) 190 UVMHIST_LOG(pmapsegtabhist, 191 "pte[%zu] = %#"PRIxPTE, 192 j, pte_value(pte[j]), 0, 0); 193 #endif 194 panic("%s: pte[%zu] entry at %p not 0 (%#"PRIxPTE")", 195 caller, i, &pte[i], pte_value(pte[i])); 196 } 197 #endif 198 } 199 200 static inline struct vm_page * 201 pmap_pte_pagealloc(void) 202 { 203 struct vm_page *pg; 204 205 pg = PMAP_ALLOC_POOLPAGE(UVM_PGA_ZERO|UVM_PGA_USERESERVE); 206 if (pg) { 207 #ifdef UVM_PAGE_TRKOWN 208 pg->owner_tag = NULL; 209 #endif 210 UVM_PAGE_OWN(pg, "pmap-ptp"); 211 } 212 213 return pg; 214 } 215 216 static inline pt_entry_t * 217 pmap_segmap(struct pmap *pmap, vaddr_t va) 218 { 219 pmap_segtab_t *stp = pmap->pm_segtab; 220 KASSERTMSG(pmap != pmap_kernel() || !pmap_md_direct_mapped_vaddr_p(va), 221 "pmap %p va %#" PRIxVADDR, pmap, va); 222 #ifdef _LP64 223 stp = stp->seg_seg[(va >> XSEGSHIFT) & (NSEGPG - 1)]; 224 if (stp == NULL) 225 return NULL; 226 #endif 227 228 return stp->seg_tab[(va >> SEGSHIFT) & (PMAP_SEGTABSIZE - 1)]; 229 } 230 231 pt_entry_t * 232 pmap_pte_lookup(pmap_t pmap, vaddr_t va) 233 { 234 pt_entry_t *pte = pmap_segmap(pmap, va); 235 if (pte == NULL) 236 return NULL; 237 238 return pte + ((va >> PGSHIFT) & (NPTEPG - 1)); 239 } 240 241 /* 242 * Insert the segtab into the segtab freelist. 243 */ 244 static void 245 pmap_segtab_free(pmap_segtab_t *stp) 246 { 247 UVMHIST_FUNC(__func__); 248 249 UVMHIST_CALLARGS(pmapsegtabhist, "stp=%#jx", stp, 0, 0, 0); 250 251 mutex_spin_enter(&pmap_segtab_lock); 252 stp->seg_seg[0] = pmap_segtab_info.free_segtab; 253 pmap_segtab_info.free_segtab = stp; 254 SEGTAB_ADD(nput, 1); 255 mutex_spin_exit(&pmap_segtab_lock); 256 } 257 258 static void 259 pmap_segtab_release(pmap_t pmap, pmap_segtab_t **stp_p, bool free_stp, 260 pte_callback_t callback, uintptr_t flags, 261 vaddr_t va, vsize_t vinc) 262 { 263 pmap_segtab_t *stp = *stp_p; 264 265 UVMHIST_FUNC(__func__); 266 UVMHIST_CALLARGS(pmapsegtabhist, "pm=%#jx stpp=%#jx free=%jd", 267 (uintptr_t)pmap, (uintptr_t)stp_p, free_stp, 0); 268 UVMHIST_LOG(pmapsegtabhist, " callback=%jx flags=%jx va=%jx vinc=%jx", 269 (uintptr_t)callback, flags, (uintptr_t)va, (uintptr_t)vinc); 270 for (size_t i = (va / vinc) & (PMAP_SEGTABSIZE - 1); 271 i < PMAP_SEGTABSIZE; 272 i++, va += vinc) { 273 #ifdef _LP64 274 if (vinc > NBSEG) { 275 if (stp->seg_seg[i] != NULL) { 276 UVMHIST_LOG(pmapsegtabhist, 277 " recursing %jd", i, 0, 0, 0); 278 pmap_segtab_release(pmap, &stp->seg_seg[i], 279 true, callback, flags, va, vinc / NSEGPG); 280 KASSERT(stp->seg_seg[i] == NULL); 281 } 282 continue; 283 } 284 #endif 285 KASSERT(vinc == NBSEG); 286 287 /* get pointer to segment map */ 288 pt_entry_t *pte = stp->seg_tab[i]; 289 if (pte == NULL) 290 continue; 291 pmap_check_ptes(pte, __func__); 292 293 /* 294 * If our caller wants a callback, do so. 295 */ 296 if (callback != NULL) { 297 (*callback)(pmap, va, va + vinc, pte, flags); 298 } 299 300 // PMAP_UNMAP_POOLPAGE should handle any VCA issues itself 301 paddr_t pa = PMAP_UNMAP_POOLPAGE((vaddr_t)pte); 302 struct vm_page *pg = PHYS_TO_VM_PAGE(pa); 303 #ifdef PMAP_PTP_CACHE 304 mutex_spin_enter(&pmap_segtab_lock); 305 LIST_INSERT_HEAD(&pmap_segtab_info.ptp_pgflist, pg, pageq.list); 306 mutex_spin_exit(&pmap_segtab_lock); 307 #else 308 uvm_pagefree(pg); 309 #endif 310 311 stp->seg_tab[i] = NULL; 312 UVMHIST_LOG(pmapsegtabhist, " zeroing tab[%jd]", i, 0, 0, 0); 313 } 314 315 if (free_stp) { 316 pmap_check_stp(stp, __func__, 317 vinc == NBSEG ? "release seg" : "release xseg"); 318 pmap_segtab_free(stp); 319 *stp_p = NULL; 320 } 321 } 322 323 /* 324 * Create and return a physical map. 325 * 326 * If the size specified for the map 327 * is zero, the map is an actual physical 328 * map, and may be referenced by the 329 * hardware. 330 * 331 * If the size specified is non-zero, 332 * the map will be used in software only, and 333 * is bounded by that size. 334 */ 335 static pmap_segtab_t * 336 pmap_segtab_alloc(void) 337 { 338 pmap_segtab_t *stp; 339 bool found_on_freelist = false; 340 341 UVMHIST_FUNC(__func__); 342 again: 343 mutex_spin_enter(&pmap_segtab_lock); 344 if (__predict_true((stp = pmap_segtab_info.free_segtab) != NULL)) { 345 pmap_segtab_info.free_segtab = stp->seg_seg[0]; 346 stp->seg_seg[0] = NULL; 347 SEGTAB_ADD(nget, 1); 348 found_on_freelist = true; 349 UVMHIST_CALLARGS(pmapsegtabhist, "freelist stp=%#jx", stp, 0, 0, 0); 350 } 351 mutex_spin_exit(&pmap_segtab_lock); 352 353 if (__predict_false(stp == NULL)) { 354 struct vm_page * const stp_pg = pmap_pte_pagealloc(); 355 356 if (__predict_false(stp_pg == NULL)) { 357 /* 358 * XXX What else can we do? Could we deadlock here? 359 */ 360 uvm_wait("segtab"); 361 goto again; 362 } 363 SEGTAB_ADD(npage, 1); 364 const paddr_t stp_pa = VM_PAGE_TO_PHYS(stp_pg); 365 366 stp = (pmap_segtab_t *)PMAP_MAP_POOLPAGE(stp_pa); 367 UVMHIST_CALLARGS(pmapsegtabhist, "new stp=%#jx", stp, 0, 0, 0); 368 const size_t n = NBPG / sizeof(*stp); 369 if (n > 1) { 370 /* 371 * link all the segtabs in this page together 372 */ 373 for (size_t i = 1; i < n - 1; i++) { 374 stp[i].seg_seg[0] = &stp[i+1]; 375 } 376 /* 377 * Now link the new segtabs into the free segtab list. 378 */ 379 mutex_spin_enter(&pmap_segtab_lock); 380 stp[n-1].seg_seg[0] = pmap_segtab_info.free_segtab; 381 pmap_segtab_info.free_segtab = stp + 1; 382 SEGTAB_ADD(nput, n - 1); 383 mutex_spin_exit(&pmap_segtab_lock); 384 } 385 } 386 387 pmap_check_stp(stp, __func__, 388 found_on_freelist ? "from free list" : "allocated"); 389 390 return stp; 391 } 392 393 /* 394 * Allocate the top segment table for the pmap. 395 */ 396 void 397 pmap_segtab_init(pmap_t pmap) 398 { 399 400 pmap->pm_segtab = pmap_segtab_alloc(); 401 } 402 403 /* 404 * Retire the given physical map from service. 405 * Should only be called if the map contains 406 * no valid mappings. 407 */ 408 void 409 pmap_segtab_destroy(pmap_t pmap, pte_callback_t func, uintptr_t flags) 410 { 411 if (pmap->pm_segtab == NULL) 412 return; 413 414 #ifdef _LP64 415 const vsize_t vinc = NBXSEG; 416 #else 417 const vsize_t vinc = NBSEG; 418 #endif 419 pmap_segtab_release(pmap, &pmap->pm_segtab, 420 func == NULL, func, flags, pmap->pm_minaddr, vinc); 421 } 422 423 /* 424 * Make a new pmap (vmspace) active for the given process. 425 */ 426 void 427 pmap_segtab_activate(struct pmap *pm, struct lwp *l) 428 { 429 if (l == curlwp) { 430 struct cpu_info * const ci = l->l_cpu; 431 pmap_md_xtab_activate(pm, l); 432 KASSERT(pm == l->l_proc->p_vmspace->vm_map.pmap); 433 if (pm == pmap_kernel()) { 434 ci->ci_pmap_user_segtab = PMAP_INVALID_SEGTAB_ADDRESS; 435 #ifdef _LP64 436 ci->ci_pmap_user_seg0tab = PMAP_INVALID_SEGTAB_ADDRESS; 437 #endif 438 } else { 439 ci->ci_pmap_user_segtab = pm->pm_segtab; 440 #ifdef _LP64 441 ci->ci_pmap_user_seg0tab = pm->pm_segtab->seg_seg[0]; 442 #endif 443 } 444 } 445 } 446 447 448 void 449 pmap_segtab_deactivate(pmap_t pm) 450 { 451 452 pmap_md_xtab_deactivate(pm); 453 454 curcpu()->ci_pmap_user_segtab = PMAP_INVALID_SEGTAB_ADDRESS; 455 #ifdef _LP64 456 curcpu()->ci_pmap_user_seg0tab = NULL; 457 #endif 458 459 } 460 461 /* 462 * Act on the given range of addresses from the specified map. 463 * 464 * It is assumed that the start and end are properly rounded to 465 * the page size. 466 */ 467 void 468 pmap_pte_process(pmap_t pmap, vaddr_t sva, vaddr_t eva, 469 pte_callback_t callback, uintptr_t flags) 470 { 471 #if 0 472 printf("%s: %p, %"PRIxVADDR", %"PRIxVADDR", %p, %"PRIxPTR"\n", 473 __func__, pmap, sva, eva, callback, flags); 474 #endif 475 while (sva < eva) { 476 vaddr_t lastseg_va = pmap_trunc_seg(sva) + NBSEG; 477 if (lastseg_va == 0 || lastseg_va > eva) 478 lastseg_va = eva; 479 480 /* 481 * If VA belongs to an unallocated segment, 482 * skip to the next segment boundary. 483 */ 484 pt_entry_t * const ptep = pmap_pte_lookup(pmap, sva); 485 if (ptep != NULL) { 486 /* 487 * Callback to deal with the ptes for this segment. 488 */ 489 (*callback)(pmap, sva, lastseg_va, ptep, flags); 490 } 491 /* 492 * In theory we could release pages with no entries, 493 * but that takes more effort than we want here. 494 */ 495 sva = lastseg_va; 496 } 497 } 498 499 /* 500 * Return a pointer for the pte that corresponds to the specified virtual 501 * address (va) in the target physical map, allocating if needed. 502 */ 503 pt_entry_t * 504 pmap_pte_reserve(pmap_t pmap, vaddr_t va, int flags) 505 { 506 pmap_segtab_t *stp = pmap->pm_segtab; 507 pt_entry_t *pte; 508 UVMHIST_FUNC(__func__); 509 510 pte = pmap_pte_lookup(pmap, va); 511 if (__predict_false(pte == NULL)) { 512 #ifdef _LP64 513 pmap_segtab_t ** const stp_p = 514 &stp->seg_seg[(va >> XSEGSHIFT) & (NSEGPG - 1)]; 515 if (__predict_false((stp = *stp_p) == NULL)) { 516 pmap_segtab_t *nstp = pmap_segtab_alloc(); 517 #ifdef MULTIPROCESSOR 518 pmap_segtab_t *ostp = atomic_cas_ptr(stp_p, NULL, nstp); 519 if (__predict_false(ostp != NULL)) { 520 pmap_check_stp(nstp, __func__, "reserve"); 521 pmap_segtab_free(nstp); 522 nstp = ostp; 523 } 524 #else 525 *stp_p = nstp; 526 #endif /* MULTIPROCESSOR */ 527 stp = nstp; 528 } 529 KASSERT(stp == pmap->pm_segtab->seg_seg[(va >> XSEGSHIFT) & (NSEGPG - 1)]); 530 #endif /* _LP64 */ 531 struct vm_page *pg = NULL; 532 #ifdef PMAP_PTP_CACHE 533 mutex_spin_enter(&pmap_segtab_lock); 534 if ((pg = LIST_FIRST(&pmap_segtab_info.ptp_pgflist)) != NULL) { 535 LIST_REMOVE(pg, pageq.list); 536 KASSERT(LIST_FIRST(&pmap_segtab_info.ptp_pgflist) != pg); 537 } 538 mutex_spin_exit(&pmap_segtab_lock); 539 #endif 540 if (pg == NULL) 541 pg = pmap_pte_pagealloc(); 542 if (pg == NULL) { 543 if (flags & PMAP_CANFAIL) 544 return NULL; 545 panic("%s: cannot allocate page table page " 546 "for va %" PRIxVADDR, __func__, va); 547 } 548 549 const paddr_t pa = VM_PAGE_TO_PHYS(pg); 550 pte = (pt_entry_t *)PMAP_MAP_POOLPAGE(pa); 551 pt_entry_t ** const pte_p = 552 &stp->seg_tab[(va >> SEGSHIFT) & (PMAP_SEGTABSIZE - 1)]; 553 #ifdef MULTIPROCESSOR 554 pt_entry_t *opte = atomic_cas_ptr(pte_p, NULL, pte); 555 /* 556 * If another thread allocated the segtab needed for this va 557 * free the page we just allocated. 558 */ 559 if (__predict_false(opte != NULL)) { 560 #ifdef PMAP_PTP_CACHE 561 mutex_spin_enter(&pmap_segtab_lock); 562 LIST_INSERT_HEAD(&pmap_segtab_info.ptp_pgflist, 563 pg, pageq.list); 564 mutex_spin_exit(&pmap_segtab_lock); 565 #else 566 PMAP_UNMAP_POOLPAGE((vaddr_t)pte); 567 uvm_pagefree(pg); 568 #endif 569 pte = opte; 570 } 571 #else 572 *pte_p = pte; 573 #endif 574 KASSERT(pte == stp->seg_tab[(va >> SEGSHIFT) & (PMAP_SEGTABSIZE - 1)]); 575 UVMHIST_CALLARGS(pmapsegtabhist, "pm=%#jx va=%#jx -> tab[%jd]=%jx", 576 (uintptr_t)pmap, (uintptr_t)va, 577 (va >> SEGSHIFT) & (PMAP_SEGTABSIZE - 1), pte); 578 579 pmap_check_ptes(pte, __func__); 580 pte += (va >> PGSHIFT) & (NPTEPG - 1); 581 } 582 583 return pte; 584 } 585