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