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