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