1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * High memory handling common code and variables. 4 * 5 * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de 6 * Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de 7 * 8 * 9 * Redesigned the x86 32-bit VM architecture to deal with 10 * 64-bit physical space. With current x86 CPUs this 11 * means up to 64 Gigabytes physical RAM. 12 * 13 * Rewrote high memory support to move the page cache into 14 * high memory. Implemented permanent (schedulable) kmaps 15 * based on Linus' idea. 16 * 17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> 18 */ 19 20 #include <linux/mm.h> 21 #include <linux/export.h> 22 #include <linux/swap.h> 23 #include <linux/bio.h> 24 #include <linux/pagemap.h> 25 #include <linux/mempool.h> 26 #include <linux/init.h> 27 #include <linux/hash.h> 28 #include <linux/highmem.h> 29 #include <linux/kgdb.h> 30 #include <asm/tlbflush.h> 31 #include <linux/vmalloc.h> 32 33 #ifdef CONFIG_KMAP_LOCAL 34 static inline int kmap_local_calc_idx(int idx) 35 { 36 return idx + KM_MAX_IDX * smp_processor_id(); 37 } 38 39 #ifndef arch_kmap_local_map_idx 40 #define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx) 41 #endif 42 #endif /* CONFIG_KMAP_LOCAL */ 43 44 /* 45 * Virtual_count is not a pure "count". 46 * 0 means that it is not mapped, and has not been mapped 47 * since a TLB flush - it is usable. 48 * 1 means that there are no users, but it has been mapped 49 * since the last TLB flush - so we can't use it. 50 * n means that there are (n-1) current users of it. 51 */ 52 #ifdef CONFIG_HIGHMEM 53 54 /* 55 * Architecture with aliasing data cache may define the following family of 56 * helper functions in its asm/highmem.h to control cache color of virtual 57 * addresses where physical memory pages are mapped by kmap. 58 */ 59 #ifndef get_pkmap_color 60 61 /* 62 * Determine color of virtual address where the page should be mapped. 63 */ 64 static inline unsigned int get_pkmap_color(struct page *page) 65 { 66 return 0; 67 } 68 #define get_pkmap_color get_pkmap_color 69 70 /* 71 * Get next index for mapping inside PKMAP region for page with given color. 72 */ 73 static inline unsigned int get_next_pkmap_nr(unsigned int color) 74 { 75 static unsigned int last_pkmap_nr; 76 77 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK; 78 return last_pkmap_nr; 79 } 80 81 /* 82 * Determine if page index inside PKMAP region (pkmap_nr) of given color 83 * has wrapped around PKMAP region end. When this happens an attempt to 84 * flush all unused PKMAP slots is made. 85 */ 86 static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color) 87 { 88 return pkmap_nr == 0; 89 } 90 91 /* 92 * Get the number of PKMAP entries of the given color. If no free slot is 93 * found after checking that many entries, kmap will sleep waiting for 94 * someone to call kunmap and free PKMAP slot. 95 */ 96 static inline int get_pkmap_entries_count(unsigned int color) 97 { 98 return LAST_PKMAP; 99 } 100 101 /* 102 * Get head of a wait queue for PKMAP entries of the given color. 103 * Wait queues for different mapping colors should be independent to avoid 104 * unnecessary wakeups caused by freeing of slots of other colors. 105 */ 106 static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color) 107 { 108 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); 109 110 return &pkmap_map_wait; 111 } 112 #endif 113 114 unsigned long __nr_free_highpages(void) 115 { 116 unsigned long pages = 0; 117 struct zone *zone; 118 119 for_each_populated_zone(zone) { 120 if (is_highmem(zone)) 121 pages += zone_page_state(zone, NR_FREE_PAGES); 122 } 123 124 return pages; 125 } 126 127 unsigned long __totalhigh_pages(void) 128 { 129 unsigned long pages = 0; 130 struct zone *zone; 131 132 for_each_populated_zone(zone) { 133 if (is_highmem(zone)) 134 pages += zone_managed_pages(zone); 135 } 136 137 return pages; 138 } 139 EXPORT_SYMBOL(__totalhigh_pages); 140 141 static int pkmap_count[LAST_PKMAP]; 142 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); 143 144 pte_t *pkmap_page_table; 145 146 /* 147 * Most architectures have no use for kmap_high_get(), so let's abstract 148 * the disabling of IRQ out of the locking in that case to save on a 149 * potential useless overhead. 150 */ 151 #ifdef ARCH_NEEDS_KMAP_HIGH_GET 152 #define lock_kmap() spin_lock_irq(&kmap_lock) 153 #define unlock_kmap() spin_unlock_irq(&kmap_lock) 154 #define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags) 155 #define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags) 156 #else 157 #define lock_kmap() spin_lock(&kmap_lock) 158 #define unlock_kmap() spin_unlock(&kmap_lock) 159 #define lock_kmap_any(flags) \ 160 do { spin_lock(&kmap_lock); (void)(flags); } while (0) 161 #define unlock_kmap_any(flags) \ 162 do { spin_unlock(&kmap_lock); (void)(flags); } while (0) 163 #endif 164 165 struct page *__kmap_to_page(void *vaddr) 166 { 167 unsigned long base = (unsigned long) vaddr & PAGE_MASK; 168 struct kmap_ctrl *kctrl = ¤t->kmap_ctrl; 169 unsigned long addr = (unsigned long)vaddr; 170 int i; 171 172 /* kmap() mappings */ 173 if (WARN_ON_ONCE(addr >= PKMAP_ADDR(0) && 174 addr < PKMAP_ADDR(LAST_PKMAP))) 175 return pte_page(ptep_get(&pkmap_page_table[PKMAP_NR(addr)])); 176 177 /* kmap_local_page() mappings */ 178 if (WARN_ON_ONCE(base >= __fix_to_virt(FIX_KMAP_END) && 179 base < __fix_to_virt(FIX_KMAP_BEGIN))) { 180 for (i = 0; i < kctrl->idx; i++) { 181 unsigned long base_addr; 182 int idx; 183 184 idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); 185 base_addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 186 187 if (base_addr == base) 188 return pte_page(kctrl->pteval[i]); 189 } 190 } 191 192 return virt_to_page(vaddr); 193 } 194 EXPORT_SYMBOL(__kmap_to_page); 195 196 static void flush_all_zero_pkmaps(void) 197 { 198 int i; 199 int need_flush = 0; 200 201 flush_cache_kmaps(); 202 203 for (i = 0; i < LAST_PKMAP; i++) { 204 struct page *page; 205 pte_t ptent; 206 207 /* 208 * zero means we don't have anything to do, 209 * >1 means that it is still in use. Only 210 * a count of 1 means that it is free but 211 * needs to be unmapped 212 */ 213 if (pkmap_count[i] != 1) 214 continue; 215 pkmap_count[i] = 0; 216 217 /* sanity check */ 218 ptent = ptep_get(&pkmap_page_table[i]); 219 BUG_ON(pte_none(ptent)); 220 221 /* 222 * Don't need an atomic fetch-and-clear op here; 223 * no-one has the page mapped, and cannot get at 224 * its virtual address (and hence PTE) without first 225 * getting the kmap_lock (which is held here). 226 * So no dangers, even with speculative execution. 227 */ 228 page = pte_page(ptent); 229 pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]); 230 231 set_page_address(page, NULL); 232 need_flush = 1; 233 } 234 if (need_flush) 235 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP)); 236 } 237 238 void __kmap_flush_unused(void) 239 { 240 lock_kmap(); 241 flush_all_zero_pkmaps(); 242 unlock_kmap(); 243 } 244 245 static inline unsigned long map_new_virtual(struct page *page) 246 { 247 unsigned long vaddr; 248 int count; 249 unsigned int last_pkmap_nr; 250 unsigned int color = get_pkmap_color(page); 251 252 start: 253 count = get_pkmap_entries_count(color); 254 /* Find an empty entry */ 255 for (;;) { 256 last_pkmap_nr = get_next_pkmap_nr(color); 257 if (no_more_pkmaps(last_pkmap_nr, color)) { 258 flush_all_zero_pkmaps(); 259 count = get_pkmap_entries_count(color); 260 } 261 if (!pkmap_count[last_pkmap_nr]) 262 break; /* Found a usable entry */ 263 if (--count) 264 continue; 265 266 /* 267 * Sleep for somebody else to unmap their entries 268 */ 269 { 270 DECLARE_WAITQUEUE(wait, current); 271 wait_queue_head_t *pkmap_map_wait = 272 get_pkmap_wait_queue_head(color); 273 274 __set_current_state(TASK_UNINTERRUPTIBLE); 275 add_wait_queue(pkmap_map_wait, &wait); 276 unlock_kmap(); 277 schedule(); 278 remove_wait_queue(pkmap_map_wait, &wait); 279 lock_kmap(); 280 281 /* Somebody else might have mapped it while we slept */ 282 if (page_address(page)) 283 return (unsigned long)page_address(page); 284 285 /* Re-start */ 286 goto start; 287 } 288 } 289 vaddr = PKMAP_ADDR(last_pkmap_nr); 290 set_pte_at(&init_mm, vaddr, 291 &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot)); 292 293 pkmap_count[last_pkmap_nr] = 1; 294 set_page_address(page, (void *)vaddr); 295 296 return vaddr; 297 } 298 299 /** 300 * kmap_high - map a highmem page into memory 301 * @page: &struct page to map 302 * 303 * Returns the page's virtual memory address. 304 * 305 * We cannot call this from interrupts, as it may block. 306 */ 307 void *kmap_high(struct page *page) 308 { 309 unsigned long vaddr; 310 311 /* 312 * For highmem pages, we can't trust "virtual" until 313 * after we have the lock. 314 */ 315 lock_kmap(); 316 vaddr = (unsigned long)page_address(page); 317 if (!vaddr) 318 vaddr = map_new_virtual(page); 319 pkmap_count[PKMAP_NR(vaddr)]++; 320 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2); 321 unlock_kmap(); 322 return (void *) vaddr; 323 } 324 EXPORT_SYMBOL(kmap_high); 325 326 #ifdef ARCH_NEEDS_KMAP_HIGH_GET 327 /** 328 * kmap_high_get - pin a highmem page into memory 329 * @page: &struct page to pin 330 * 331 * Returns the page's current virtual memory address, or NULL if no mapping 332 * exists. If and only if a non null address is returned then a 333 * matching call to kunmap_high() is necessary. 334 * 335 * This can be called from any context. 336 */ 337 void *kmap_high_get(struct page *page) 338 { 339 unsigned long vaddr, flags; 340 341 lock_kmap_any(flags); 342 vaddr = (unsigned long)page_address(page); 343 if (vaddr) { 344 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1); 345 pkmap_count[PKMAP_NR(vaddr)]++; 346 } 347 unlock_kmap_any(flags); 348 return (void *) vaddr; 349 } 350 #endif 351 352 /** 353 * kunmap_high - unmap a highmem page into memory 354 * @page: &struct page to unmap 355 * 356 * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called 357 * only from user context. 358 */ 359 void kunmap_high(struct page *page) 360 { 361 unsigned long vaddr; 362 unsigned long nr; 363 unsigned long flags; 364 int need_wakeup; 365 unsigned int color = get_pkmap_color(page); 366 wait_queue_head_t *pkmap_map_wait; 367 368 lock_kmap_any(flags); 369 vaddr = (unsigned long)page_address(page); 370 BUG_ON(!vaddr); 371 nr = PKMAP_NR(vaddr); 372 373 /* 374 * A count must never go down to zero 375 * without a TLB flush! 376 */ 377 need_wakeup = 0; 378 switch (--pkmap_count[nr]) { 379 case 0: 380 BUG(); 381 case 1: 382 /* 383 * Avoid an unnecessary wake_up() function call. 384 * The common case is pkmap_count[] == 1, but 385 * no waiters. 386 * The tasks queued in the wait-queue are guarded 387 * by both the lock in the wait-queue-head and by 388 * the kmap_lock. As the kmap_lock is held here, 389 * no need for the wait-queue-head's lock. Simply 390 * test if the queue is empty. 391 */ 392 pkmap_map_wait = get_pkmap_wait_queue_head(color); 393 need_wakeup = waitqueue_active(pkmap_map_wait); 394 } 395 unlock_kmap_any(flags); 396 397 /* do wake-up, if needed, race-free outside of the spin lock */ 398 if (need_wakeup) 399 wake_up(pkmap_map_wait); 400 } 401 EXPORT_SYMBOL(kunmap_high); 402 403 void zero_user_segments(struct page *page, unsigned start1, unsigned end1, 404 unsigned start2, unsigned end2) 405 { 406 unsigned int i; 407 408 BUG_ON(end1 > page_size(page) || end2 > page_size(page)); 409 410 if (start1 >= end1) 411 start1 = end1 = 0; 412 if (start2 >= end2) 413 start2 = end2 = 0; 414 415 for (i = 0; i < compound_nr(page); i++) { 416 void *kaddr = NULL; 417 418 if (start1 >= PAGE_SIZE) { 419 start1 -= PAGE_SIZE; 420 end1 -= PAGE_SIZE; 421 } else { 422 unsigned this_end = min_t(unsigned, end1, PAGE_SIZE); 423 424 if (end1 > start1) { 425 kaddr = kmap_local_page(page + i); 426 memset(kaddr + start1, 0, this_end - start1); 427 } 428 end1 -= this_end; 429 start1 = 0; 430 } 431 432 if (start2 >= PAGE_SIZE) { 433 start2 -= PAGE_SIZE; 434 end2 -= PAGE_SIZE; 435 } else { 436 unsigned this_end = min_t(unsigned, end2, PAGE_SIZE); 437 438 if (end2 > start2) { 439 if (!kaddr) 440 kaddr = kmap_local_page(page + i); 441 memset(kaddr + start2, 0, this_end - start2); 442 } 443 end2 -= this_end; 444 start2 = 0; 445 } 446 447 if (kaddr) { 448 kunmap_local(kaddr); 449 flush_dcache_page(page + i); 450 } 451 452 if (!end1 && !end2) 453 break; 454 } 455 456 BUG_ON((start1 | start2 | end1 | end2) != 0); 457 } 458 EXPORT_SYMBOL(zero_user_segments); 459 #endif /* CONFIG_HIGHMEM */ 460 461 #ifdef CONFIG_KMAP_LOCAL 462 463 #include <asm/kmap_size.h> 464 465 /* 466 * With DEBUG_KMAP_LOCAL the stack depth is doubled and every second 467 * slot is unused which acts as a guard page 468 */ 469 #ifdef CONFIG_DEBUG_KMAP_LOCAL 470 # define KM_INCR 2 471 #else 472 # define KM_INCR 1 473 #endif 474 475 static inline int kmap_local_idx_push(void) 476 { 477 WARN_ON_ONCE(in_hardirq() && !irqs_disabled()); 478 current->kmap_ctrl.idx += KM_INCR; 479 BUG_ON(current->kmap_ctrl.idx >= KM_MAX_IDX); 480 return current->kmap_ctrl.idx - 1; 481 } 482 483 static inline int kmap_local_idx(void) 484 { 485 return current->kmap_ctrl.idx - 1; 486 } 487 488 static inline void kmap_local_idx_pop(void) 489 { 490 current->kmap_ctrl.idx -= KM_INCR; 491 BUG_ON(current->kmap_ctrl.idx < 0); 492 } 493 494 #ifndef arch_kmap_local_post_map 495 # define arch_kmap_local_post_map(vaddr, pteval) do { } while (0) 496 #endif 497 498 #ifndef arch_kmap_local_pre_unmap 499 # define arch_kmap_local_pre_unmap(vaddr) do { } while (0) 500 #endif 501 502 #ifndef arch_kmap_local_post_unmap 503 # define arch_kmap_local_post_unmap(vaddr) do { } while (0) 504 #endif 505 506 #ifndef arch_kmap_local_unmap_idx 507 #define arch_kmap_local_unmap_idx(idx, vaddr) kmap_local_calc_idx(idx) 508 #endif 509 510 #ifndef arch_kmap_local_high_get 511 static inline void *arch_kmap_local_high_get(struct page *page) 512 { 513 return NULL; 514 } 515 #endif 516 517 #ifndef arch_kmap_local_set_pte 518 #define arch_kmap_local_set_pte(mm, vaddr, ptep, ptev) \ 519 set_pte_at(mm, vaddr, ptep, ptev) 520 #endif 521 522 /* Unmap a local mapping which was obtained by kmap_high_get() */ 523 static inline bool kmap_high_unmap_local(unsigned long vaddr) 524 { 525 #ifdef ARCH_NEEDS_KMAP_HIGH_GET 526 if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) { 527 kunmap_high(pte_page(ptep_get(&pkmap_page_table[PKMAP_NR(vaddr)]))); 528 return true; 529 } 530 #endif 531 return false; 532 } 533 534 static pte_t *__kmap_pte; 535 536 static pte_t *kmap_get_pte(unsigned long vaddr, int idx) 537 { 538 if (IS_ENABLED(CONFIG_KMAP_LOCAL_NON_LINEAR_PTE_ARRAY)) 539 /* 540 * Set by the arch if __kmap_pte[-idx] does not produce 541 * the correct entry. 542 */ 543 return virt_to_kpte(vaddr); 544 if (!__kmap_pte) 545 __kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN)); 546 return &__kmap_pte[-idx]; 547 } 548 549 void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot) 550 { 551 pte_t pteval, *kmap_pte; 552 unsigned long vaddr; 553 int idx; 554 555 /* 556 * Disable migration so resulting virtual address is stable 557 * across preemption. 558 */ 559 migrate_disable(); 560 preempt_disable(); 561 idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn); 562 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 563 kmap_pte = kmap_get_pte(vaddr, idx); 564 BUG_ON(!pte_none(ptep_get(kmap_pte))); 565 pteval = pfn_pte(pfn, prot); 566 arch_kmap_local_set_pte(&init_mm, vaddr, kmap_pte, pteval); 567 arch_kmap_local_post_map(vaddr, pteval); 568 current->kmap_ctrl.pteval[kmap_local_idx()] = pteval; 569 preempt_enable(); 570 571 return (void *)vaddr; 572 } 573 EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot); 574 575 void *__kmap_local_page_prot(struct page *page, pgprot_t prot) 576 { 577 void *kmap; 578 579 /* 580 * To broaden the usage of the actual kmap_local() machinery always map 581 * pages when debugging is enabled and the architecture has no problems 582 * with alias mappings. 583 */ 584 if (!IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) && !PageHighMem(page)) 585 return page_address(page); 586 587 /* Try kmap_high_get() if architecture has it enabled */ 588 kmap = arch_kmap_local_high_get(page); 589 if (kmap) 590 return kmap; 591 592 return __kmap_local_pfn_prot(page_to_pfn(page), prot); 593 } 594 EXPORT_SYMBOL(__kmap_local_page_prot); 595 596 void kunmap_local_indexed(const void *vaddr) 597 { 598 unsigned long addr = (unsigned long) vaddr & PAGE_MASK; 599 pte_t *kmap_pte; 600 int idx; 601 602 if (addr < __fix_to_virt(FIX_KMAP_END) || 603 addr > __fix_to_virt(FIX_KMAP_BEGIN)) { 604 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP)) { 605 /* This _should_ never happen! See above. */ 606 WARN_ON_ONCE(1); 607 return; 608 } 609 /* 610 * Handle mappings which were obtained by kmap_high_get() 611 * first as the virtual address of such mappings is below 612 * PAGE_OFFSET. Warn for all other addresses which are in 613 * the user space part of the virtual address space. 614 */ 615 if (!kmap_high_unmap_local(addr)) 616 WARN_ON_ONCE(addr < PAGE_OFFSET); 617 return; 618 } 619 620 preempt_disable(); 621 idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr); 622 WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); 623 624 kmap_pte = kmap_get_pte(addr, idx); 625 arch_kmap_local_pre_unmap(addr); 626 pte_clear(&init_mm, addr, kmap_pte); 627 arch_kmap_local_post_unmap(addr); 628 current->kmap_ctrl.pteval[kmap_local_idx()] = __pte(0); 629 kmap_local_idx_pop(); 630 preempt_enable(); 631 migrate_enable(); 632 } 633 EXPORT_SYMBOL(kunmap_local_indexed); 634 635 /* 636 * Invoked before switch_to(). This is safe even when during or after 637 * clearing the maps an interrupt which needs a kmap_local happens because 638 * the task::kmap_ctrl.idx is not modified by the unmapping code so a 639 * nested kmap_local will use the next unused index and restore the index 640 * on unmap. The already cleared kmaps of the outgoing task are irrelevant 641 * because the interrupt context does not know about them. The same applies 642 * when scheduling back in for an interrupt which happens before the 643 * restore is complete. 644 */ 645 void __kmap_local_sched_out(void) 646 { 647 struct task_struct *tsk = current; 648 pte_t *kmap_pte; 649 int i; 650 651 /* Clear kmaps */ 652 for (i = 0; i < tsk->kmap_ctrl.idx; i++) { 653 pte_t pteval = tsk->kmap_ctrl.pteval[i]; 654 unsigned long addr; 655 int idx; 656 657 /* With debug all even slots are unmapped and act as guard */ 658 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { 659 WARN_ON_ONCE(pte_val(pteval) != 0); 660 continue; 661 } 662 if (WARN_ON_ONCE(pte_none(pteval))) 663 continue; 664 665 /* 666 * This is a horrible hack for XTENSA to calculate the 667 * coloured PTE index. Uses the PFN encoded into the pteval 668 * and the map index calculation because the actual mapped 669 * virtual address is not stored in task::kmap_ctrl. 670 * For any sane architecture this is optimized out. 671 */ 672 idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); 673 674 addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 675 kmap_pte = kmap_get_pte(addr, idx); 676 arch_kmap_local_pre_unmap(addr); 677 pte_clear(&init_mm, addr, kmap_pte); 678 arch_kmap_local_post_unmap(addr); 679 } 680 } 681 682 void __kmap_local_sched_in(void) 683 { 684 struct task_struct *tsk = current; 685 pte_t *kmap_pte; 686 int i; 687 688 /* Restore kmaps */ 689 for (i = 0; i < tsk->kmap_ctrl.idx; i++) { 690 pte_t pteval = tsk->kmap_ctrl.pteval[i]; 691 unsigned long addr; 692 int idx; 693 694 /* With debug all even slots are unmapped and act as guard */ 695 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { 696 WARN_ON_ONCE(pte_val(pteval) != 0); 697 continue; 698 } 699 if (WARN_ON_ONCE(pte_none(pteval))) 700 continue; 701 702 /* See comment in __kmap_local_sched_out() */ 703 idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); 704 addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 705 kmap_pte = kmap_get_pte(addr, idx); 706 set_pte_at(&init_mm, addr, kmap_pte, pteval); 707 arch_kmap_local_post_map(addr, pteval); 708 } 709 } 710 711 void kmap_local_fork(struct task_struct *tsk) 712 { 713 if (WARN_ON_ONCE(tsk->kmap_ctrl.idx)) 714 memset(&tsk->kmap_ctrl, 0, sizeof(tsk->kmap_ctrl)); 715 } 716 717 #endif 718 719 #if defined(HASHED_PAGE_VIRTUAL) 720 721 #define PA_HASH_ORDER 7 722 723 /* 724 * Describes one page->virtual association 725 */ 726 struct page_address_map { 727 struct page *page; 728 void *virtual; 729 struct list_head list; 730 }; 731 732 static struct page_address_map page_address_maps[LAST_PKMAP]; 733 734 /* 735 * Hash table bucket 736 */ 737 static struct page_address_slot { 738 struct list_head lh; /* List of page_address_maps */ 739 spinlock_t lock; /* Protect this bucket's list */ 740 } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER]; 741 742 static struct page_address_slot *page_slot(const struct page *page) 743 { 744 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)]; 745 } 746 747 /** 748 * page_address - get the mapped virtual address of a page 749 * @page: &struct page to get the virtual address of 750 * 751 * Returns the page's virtual address. 752 */ 753 void *page_address(const struct page *page) 754 { 755 unsigned long flags; 756 void *ret; 757 struct page_address_slot *pas; 758 759 if (!PageHighMem(page)) 760 return lowmem_page_address(page); 761 762 pas = page_slot(page); 763 ret = NULL; 764 spin_lock_irqsave(&pas->lock, flags); 765 if (!list_empty(&pas->lh)) { 766 struct page_address_map *pam; 767 768 list_for_each_entry(pam, &pas->lh, list) { 769 if (pam->page == page) { 770 ret = pam->virtual; 771 break; 772 } 773 } 774 } 775 776 spin_unlock_irqrestore(&pas->lock, flags); 777 return ret; 778 } 779 EXPORT_SYMBOL(page_address); 780 781 /** 782 * set_page_address - set a page's virtual address 783 * @page: &struct page to set 784 * @virtual: virtual address to use 785 */ 786 void set_page_address(struct page *page, void *virtual) 787 { 788 unsigned long flags; 789 struct page_address_slot *pas; 790 struct page_address_map *pam; 791 792 BUG_ON(!PageHighMem(page)); 793 794 pas = page_slot(page); 795 if (virtual) { /* Add */ 796 pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)]; 797 pam->page = page; 798 pam->virtual = virtual; 799 800 spin_lock_irqsave(&pas->lock, flags); 801 list_add_tail(&pam->list, &pas->lh); 802 spin_unlock_irqrestore(&pas->lock, flags); 803 } else { /* Remove */ 804 spin_lock_irqsave(&pas->lock, flags); 805 list_for_each_entry(pam, &pas->lh, list) { 806 if (pam->page == page) { 807 list_del(&pam->list); 808 break; 809 } 810 } 811 spin_unlock_irqrestore(&pas->lock, flags); 812 } 813 } 814 815 void __init page_address_init(void) 816 { 817 int i; 818 819 for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) { 820 INIT_LIST_HEAD(&page_address_htable[i].lh); 821 spin_lock_init(&page_address_htable[i].lock); 822 } 823 } 824 825 #endif /* defined(HASHED_PAGE_VIRTUAL) */ 826