Merge tag 'x86-urgent-2022-08-13' of git://git.kernel.org/pub/scm/linux/kernel/git...
[platform/kernel/linux-starfive.git] / mm / highmem.c
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 /*
34  * Virtual_count is not a pure "count".
35  *  0 means that it is not mapped, and has not been mapped
36  *    since a TLB flush - it is usable.
37  *  1 means that there are no users, but it has been mapped
38  *    since the last TLB flush - so we can't use it.
39  *  n means that there are (n-1) current users of it.
40  */
41 #ifdef CONFIG_HIGHMEM
42
43 /*
44  * Architecture with aliasing data cache may define the following family of
45  * helper functions in its asm/highmem.h to control cache color of virtual
46  * addresses where physical memory pages are mapped by kmap.
47  */
48 #ifndef get_pkmap_color
49
50 /*
51  * Determine color of virtual address where the page should be mapped.
52  */
53 static inline unsigned int get_pkmap_color(struct page *page)
54 {
55         return 0;
56 }
57 #define get_pkmap_color get_pkmap_color
58
59 /*
60  * Get next index for mapping inside PKMAP region for page with given color.
61  */
62 static inline unsigned int get_next_pkmap_nr(unsigned int color)
63 {
64         static unsigned int last_pkmap_nr;
65
66         last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
67         return last_pkmap_nr;
68 }
69
70 /*
71  * Determine if page index inside PKMAP region (pkmap_nr) of given color
72  * has wrapped around PKMAP region end. When this happens an attempt to
73  * flush all unused PKMAP slots is made.
74  */
75 static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)
76 {
77         return pkmap_nr == 0;
78 }
79
80 /*
81  * Get the number of PKMAP entries of the given color. If no free slot is
82  * found after checking that many entries, kmap will sleep waiting for
83  * someone to call kunmap and free PKMAP slot.
84  */
85 static inline int get_pkmap_entries_count(unsigned int color)
86 {
87         return LAST_PKMAP;
88 }
89
90 /*
91  * Get head of a wait queue for PKMAP entries of the given color.
92  * Wait queues for different mapping colors should be independent to avoid
93  * unnecessary wakeups caused by freeing of slots of other colors.
94  */
95 static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
96 {
97         static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
98
99         return &pkmap_map_wait;
100 }
101 #endif
102
103 atomic_long_t _totalhigh_pages __read_mostly;
104 EXPORT_SYMBOL(_totalhigh_pages);
105
106 unsigned int __nr_free_highpages(void)
107 {
108         struct zone *zone;
109         unsigned int pages = 0;
110
111         for_each_populated_zone(zone) {
112                 if (is_highmem(zone))
113                         pages += zone_page_state(zone, NR_FREE_PAGES);
114         }
115
116         return pages;
117 }
118
119 static int pkmap_count[LAST_PKMAP];
120 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
121
122 pte_t *pkmap_page_table;
123
124 /*
125  * Most architectures have no use for kmap_high_get(), so let's abstract
126  * the disabling of IRQ out of the locking in that case to save on a
127  * potential useless overhead.
128  */
129 #ifdef ARCH_NEEDS_KMAP_HIGH_GET
130 #define lock_kmap()             spin_lock_irq(&kmap_lock)
131 #define unlock_kmap()           spin_unlock_irq(&kmap_lock)
132 #define lock_kmap_any(flags)    spin_lock_irqsave(&kmap_lock, flags)
133 #define unlock_kmap_any(flags)  spin_unlock_irqrestore(&kmap_lock, flags)
134 #else
135 #define lock_kmap()             spin_lock(&kmap_lock)
136 #define unlock_kmap()           spin_unlock(&kmap_lock)
137 #define lock_kmap_any(flags)    \
138                 do { spin_lock(&kmap_lock); (void)(flags); } while (0)
139 #define unlock_kmap_any(flags)  \
140                 do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
141 #endif
142
143 struct page *__kmap_to_page(void *vaddr)
144 {
145         unsigned long addr = (unsigned long)vaddr;
146
147         if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
148                 int i = PKMAP_NR(addr);
149
150                 return pte_page(pkmap_page_table[i]);
151         }
152
153         return virt_to_page(vaddr);
154 }
155 EXPORT_SYMBOL(__kmap_to_page);
156
157 static void flush_all_zero_pkmaps(void)
158 {
159         int i;
160         int need_flush = 0;
161
162         flush_cache_kmaps();
163
164         for (i = 0; i < LAST_PKMAP; i++) {
165                 struct page *page;
166
167                 /*
168                  * zero means we don't have anything to do,
169                  * >1 means that it is still in use. Only
170                  * a count of 1 means that it is free but
171                  * needs to be unmapped
172                  */
173                 if (pkmap_count[i] != 1)
174                         continue;
175                 pkmap_count[i] = 0;
176
177                 /* sanity check */
178                 BUG_ON(pte_none(pkmap_page_table[i]));
179
180                 /*
181                  * Don't need an atomic fetch-and-clear op here;
182                  * no-one has the page mapped, and cannot get at
183                  * its virtual address (and hence PTE) without first
184                  * getting the kmap_lock (which is held here).
185                  * So no dangers, even with speculative execution.
186                  */
187                 page = pte_page(pkmap_page_table[i]);
188                 pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]);
189
190                 set_page_address(page, NULL);
191                 need_flush = 1;
192         }
193         if (need_flush)
194                 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
195 }
196
197 void __kmap_flush_unused(void)
198 {
199         lock_kmap();
200         flush_all_zero_pkmaps();
201         unlock_kmap();
202 }
203
204 static inline unsigned long map_new_virtual(struct page *page)
205 {
206         unsigned long vaddr;
207         int count;
208         unsigned int last_pkmap_nr;
209         unsigned int color = get_pkmap_color(page);
210
211 start:
212         count = get_pkmap_entries_count(color);
213         /* Find an empty entry */
214         for (;;) {
215                 last_pkmap_nr = get_next_pkmap_nr(color);
216                 if (no_more_pkmaps(last_pkmap_nr, color)) {
217                         flush_all_zero_pkmaps();
218                         count = get_pkmap_entries_count(color);
219                 }
220                 if (!pkmap_count[last_pkmap_nr])
221                         break;  /* Found a usable entry */
222                 if (--count)
223                         continue;
224
225                 /*
226                  * Sleep for somebody else to unmap their entries
227                  */
228                 {
229                         DECLARE_WAITQUEUE(wait, current);
230                         wait_queue_head_t *pkmap_map_wait =
231                                 get_pkmap_wait_queue_head(color);
232
233                         __set_current_state(TASK_UNINTERRUPTIBLE);
234                         add_wait_queue(pkmap_map_wait, &wait);
235                         unlock_kmap();
236                         schedule();
237                         remove_wait_queue(pkmap_map_wait, &wait);
238                         lock_kmap();
239
240                         /* Somebody else might have mapped it while we slept */
241                         if (page_address(page))
242                                 return (unsigned long)page_address(page);
243
244                         /* Re-start */
245                         goto start;
246                 }
247         }
248         vaddr = PKMAP_ADDR(last_pkmap_nr);
249         set_pte_at(&init_mm, vaddr,
250                    &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
251
252         pkmap_count[last_pkmap_nr] = 1;
253         set_page_address(page, (void *)vaddr);
254
255         return vaddr;
256 }
257
258 /**
259  * kmap_high - map a highmem page into memory
260  * @page: &struct page to map
261  *
262  * Returns the page's virtual memory address.
263  *
264  * We cannot call this from interrupts, as it may block.
265  */
266 void *kmap_high(struct page *page)
267 {
268         unsigned long vaddr;
269
270         /*
271          * For highmem pages, we can't trust "virtual" until
272          * after we have the lock.
273          */
274         lock_kmap();
275         vaddr = (unsigned long)page_address(page);
276         if (!vaddr)
277                 vaddr = map_new_virtual(page);
278         pkmap_count[PKMAP_NR(vaddr)]++;
279         BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
280         unlock_kmap();
281         return (void *) vaddr;
282 }
283 EXPORT_SYMBOL(kmap_high);
284
285 #ifdef ARCH_NEEDS_KMAP_HIGH_GET
286 /**
287  * kmap_high_get - pin a highmem page into memory
288  * @page: &struct page to pin
289  *
290  * Returns the page's current virtual memory address, or NULL if no mapping
291  * exists.  If and only if a non null address is returned then a
292  * matching call to kunmap_high() is necessary.
293  *
294  * This can be called from any context.
295  */
296 void *kmap_high_get(struct page *page)
297 {
298         unsigned long vaddr, flags;
299
300         lock_kmap_any(flags);
301         vaddr = (unsigned long)page_address(page);
302         if (vaddr) {
303                 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
304                 pkmap_count[PKMAP_NR(vaddr)]++;
305         }
306         unlock_kmap_any(flags);
307         return (void *) vaddr;
308 }
309 #endif
310
311 /**
312  * kunmap_high - unmap a highmem page into memory
313  * @page: &struct page to unmap
314  *
315  * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
316  * only from user context.
317  */
318 void kunmap_high(struct page *page)
319 {
320         unsigned long vaddr;
321         unsigned long nr;
322         unsigned long flags;
323         int need_wakeup;
324         unsigned int color = get_pkmap_color(page);
325         wait_queue_head_t *pkmap_map_wait;
326
327         lock_kmap_any(flags);
328         vaddr = (unsigned long)page_address(page);
329         BUG_ON(!vaddr);
330         nr = PKMAP_NR(vaddr);
331
332         /*
333          * A count must never go down to zero
334          * without a TLB flush!
335          */
336         need_wakeup = 0;
337         switch (--pkmap_count[nr]) {
338         case 0:
339                 BUG();
340         case 1:
341                 /*
342                  * Avoid an unnecessary wake_up() function call.
343                  * The common case is pkmap_count[] == 1, but
344                  * no waiters.
345                  * The tasks queued in the wait-queue are guarded
346                  * by both the lock in the wait-queue-head and by
347                  * the kmap_lock.  As the kmap_lock is held here,
348                  * no need for the wait-queue-head's lock.  Simply
349                  * test if the queue is empty.
350                  */
351                 pkmap_map_wait = get_pkmap_wait_queue_head(color);
352                 need_wakeup = waitqueue_active(pkmap_map_wait);
353         }
354         unlock_kmap_any(flags);
355
356         /* do wake-up, if needed, race-free outside of the spin lock */
357         if (need_wakeup)
358                 wake_up(pkmap_map_wait);
359 }
360 EXPORT_SYMBOL(kunmap_high);
361
362 void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
363                 unsigned start2, unsigned end2)
364 {
365         unsigned int i;
366
367         BUG_ON(end1 > page_size(page) || end2 > page_size(page));
368
369         if (start1 >= end1)
370                 start1 = end1 = 0;
371         if (start2 >= end2)
372                 start2 = end2 = 0;
373
374         for (i = 0; i < compound_nr(page); i++) {
375                 void *kaddr = NULL;
376
377                 if (start1 >= PAGE_SIZE) {
378                         start1 -= PAGE_SIZE;
379                         end1 -= PAGE_SIZE;
380                 } else {
381                         unsigned this_end = min_t(unsigned, end1, PAGE_SIZE);
382
383                         if (end1 > start1) {
384                                 kaddr = kmap_local_page(page + i);
385                                 memset(kaddr + start1, 0, this_end - start1);
386                         }
387                         end1 -= this_end;
388                         start1 = 0;
389                 }
390
391                 if (start2 >= PAGE_SIZE) {
392                         start2 -= PAGE_SIZE;
393                         end2 -= PAGE_SIZE;
394                 } else {
395                         unsigned this_end = min_t(unsigned, end2, PAGE_SIZE);
396
397                         if (end2 > start2) {
398                                 if (!kaddr)
399                                         kaddr = kmap_local_page(page + i);
400                                 memset(kaddr + start2, 0, this_end - start2);
401                         }
402                         end2 -= this_end;
403                         start2 = 0;
404                 }
405
406                 if (kaddr) {
407                         kunmap_local(kaddr);
408                         flush_dcache_page(page + i);
409                 }
410
411                 if (!end1 && !end2)
412                         break;
413         }
414
415         BUG_ON((start1 | start2 | end1 | end2) != 0);
416 }
417 EXPORT_SYMBOL(zero_user_segments);
418 #endif /* CONFIG_HIGHMEM */
419
420 #ifdef CONFIG_KMAP_LOCAL
421
422 #include <asm/kmap_size.h>
423
424 /*
425  * With DEBUG_KMAP_LOCAL the stack depth is doubled and every second
426  * slot is unused which acts as a guard page
427  */
428 #ifdef CONFIG_DEBUG_KMAP_LOCAL
429 # define KM_INCR        2
430 #else
431 # define KM_INCR        1
432 #endif
433
434 static inline int kmap_local_idx_push(void)
435 {
436         WARN_ON_ONCE(in_hardirq() && !irqs_disabled());
437         current->kmap_ctrl.idx += KM_INCR;
438         BUG_ON(current->kmap_ctrl.idx >= KM_MAX_IDX);
439         return current->kmap_ctrl.idx - 1;
440 }
441
442 static inline int kmap_local_idx(void)
443 {
444         return current->kmap_ctrl.idx - 1;
445 }
446
447 static inline void kmap_local_idx_pop(void)
448 {
449         current->kmap_ctrl.idx -= KM_INCR;
450         BUG_ON(current->kmap_ctrl.idx < 0);
451 }
452
453 #ifndef arch_kmap_local_post_map
454 # define arch_kmap_local_post_map(vaddr, pteval)        do { } while (0)
455 #endif
456
457 #ifndef arch_kmap_local_pre_unmap
458 # define arch_kmap_local_pre_unmap(vaddr)               do { } while (0)
459 #endif
460
461 #ifndef arch_kmap_local_post_unmap
462 # define arch_kmap_local_post_unmap(vaddr)              do { } while (0)
463 #endif
464
465 #ifndef arch_kmap_local_map_idx
466 #define arch_kmap_local_map_idx(idx, pfn)       kmap_local_calc_idx(idx)
467 #endif
468
469 #ifndef arch_kmap_local_unmap_idx
470 #define arch_kmap_local_unmap_idx(idx, vaddr)   kmap_local_calc_idx(idx)
471 #endif
472
473 #ifndef arch_kmap_local_high_get
474 static inline void *arch_kmap_local_high_get(struct page *page)
475 {
476         return NULL;
477 }
478 #endif
479
480 #ifndef arch_kmap_local_set_pte
481 #define arch_kmap_local_set_pte(mm, vaddr, ptep, ptev)  \
482         set_pte_at(mm, vaddr, ptep, ptev)
483 #endif
484
485 /* Unmap a local mapping which was obtained by kmap_high_get() */
486 static inline bool kmap_high_unmap_local(unsigned long vaddr)
487 {
488 #ifdef ARCH_NEEDS_KMAP_HIGH_GET
489         if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
490                 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
491                 return true;
492         }
493 #endif
494         return false;
495 }
496
497 static inline int kmap_local_calc_idx(int idx)
498 {
499         return idx + KM_MAX_IDX * smp_processor_id();
500 }
501
502 static pte_t *__kmap_pte;
503
504 static pte_t *kmap_get_pte(unsigned long vaddr, int idx)
505 {
506         if (IS_ENABLED(CONFIG_KMAP_LOCAL_NON_LINEAR_PTE_ARRAY))
507                 /*
508                  * Set by the arch if __kmap_pte[-idx] does not produce
509                  * the correct entry.
510                  */
511                 return virt_to_kpte(vaddr);
512         if (!__kmap_pte)
513                 __kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
514         return &__kmap_pte[-idx];
515 }
516
517 void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
518 {
519         pte_t pteval, *kmap_pte;
520         unsigned long vaddr;
521         int idx;
522
523         /*
524          * Disable migration so resulting virtual address is stable
525          * across preemption.
526          */
527         migrate_disable();
528         preempt_disable();
529         idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn);
530         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
531         kmap_pte = kmap_get_pte(vaddr, idx);
532         BUG_ON(!pte_none(*kmap_pte));
533         pteval = pfn_pte(pfn, prot);
534         arch_kmap_local_set_pte(&init_mm, vaddr, kmap_pte, pteval);
535         arch_kmap_local_post_map(vaddr, pteval);
536         current->kmap_ctrl.pteval[kmap_local_idx()] = pteval;
537         preempt_enable();
538
539         return (void *)vaddr;
540 }
541 EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot);
542
543 void *__kmap_local_page_prot(struct page *page, pgprot_t prot)
544 {
545         void *kmap;
546
547         /*
548          * To broaden the usage of the actual kmap_local() machinery always map
549          * pages when debugging is enabled and the architecture has no problems
550          * with alias mappings.
551          */
552         if (!IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) && !PageHighMem(page))
553                 return page_address(page);
554
555         /* Try kmap_high_get() if architecture has it enabled */
556         kmap = arch_kmap_local_high_get(page);
557         if (kmap)
558                 return kmap;
559
560         return __kmap_local_pfn_prot(page_to_pfn(page), prot);
561 }
562 EXPORT_SYMBOL(__kmap_local_page_prot);
563
564 void kunmap_local_indexed(const void *vaddr)
565 {
566         unsigned long addr = (unsigned long) vaddr & PAGE_MASK;
567         pte_t *kmap_pte;
568         int idx;
569
570         if (addr < __fix_to_virt(FIX_KMAP_END) ||
571             addr > __fix_to_virt(FIX_KMAP_BEGIN)) {
572                 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP)) {
573                         /* This _should_ never happen! See above. */
574                         WARN_ON_ONCE(1);
575                         return;
576                 }
577                 /*
578                  * Handle mappings which were obtained by kmap_high_get()
579                  * first as the virtual address of such mappings is below
580                  * PAGE_OFFSET. Warn for all other addresses which are in
581                  * the user space part of the virtual address space.
582                  */
583                 if (!kmap_high_unmap_local(addr))
584                         WARN_ON_ONCE(addr < PAGE_OFFSET);
585                 return;
586         }
587
588         preempt_disable();
589         idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);
590         WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
591
592         kmap_pte = kmap_get_pte(addr, idx);
593         arch_kmap_local_pre_unmap(addr);
594         pte_clear(&init_mm, addr, kmap_pte);
595         arch_kmap_local_post_unmap(addr);
596         current->kmap_ctrl.pteval[kmap_local_idx()] = __pte(0);
597         kmap_local_idx_pop();
598         preempt_enable();
599         migrate_enable();
600 }
601 EXPORT_SYMBOL(kunmap_local_indexed);
602
603 /*
604  * Invoked before switch_to(). This is safe even when during or after
605  * clearing the maps an interrupt which needs a kmap_local happens because
606  * the task::kmap_ctrl.idx is not modified by the unmapping code so a
607  * nested kmap_local will use the next unused index and restore the index
608  * on unmap. The already cleared kmaps of the outgoing task are irrelevant
609  * because the interrupt context does not know about them. The same applies
610  * when scheduling back in for an interrupt which happens before the
611  * restore is complete.
612  */
613 void __kmap_local_sched_out(void)
614 {
615         struct task_struct *tsk = current;
616         pte_t *kmap_pte;
617         int i;
618
619         /* Clear kmaps */
620         for (i = 0; i < tsk->kmap_ctrl.idx; i++) {
621                 pte_t pteval = tsk->kmap_ctrl.pteval[i];
622                 unsigned long addr;
623                 int idx;
624
625                 /* With debug all even slots are unmapped and act as guard */
626                 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) {
627                         WARN_ON_ONCE(pte_val(pteval) != 0);
628                         continue;
629                 }
630                 if (WARN_ON_ONCE(pte_none(pteval)))
631                         continue;
632
633                 /*
634                  * This is a horrible hack for XTENSA to calculate the
635                  * coloured PTE index. Uses the PFN encoded into the pteval
636                  * and the map index calculation because the actual mapped
637                  * virtual address is not stored in task::kmap_ctrl.
638                  * For any sane architecture this is optimized out.
639                  */
640                 idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));
641
642                 addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
643                 kmap_pte = kmap_get_pte(addr, idx);
644                 arch_kmap_local_pre_unmap(addr);
645                 pte_clear(&init_mm, addr, kmap_pte);
646                 arch_kmap_local_post_unmap(addr);
647         }
648 }
649
650 void __kmap_local_sched_in(void)
651 {
652         struct task_struct *tsk = current;
653         pte_t *kmap_pte;
654         int i;
655
656         /* Restore kmaps */
657         for (i = 0; i < tsk->kmap_ctrl.idx; i++) {
658                 pte_t pteval = tsk->kmap_ctrl.pteval[i];
659                 unsigned long addr;
660                 int idx;
661
662                 /* With debug all even slots are unmapped and act as guard */
663                 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) {
664                         WARN_ON_ONCE(pte_val(pteval) != 0);
665                         continue;
666                 }
667                 if (WARN_ON_ONCE(pte_none(pteval)))
668                         continue;
669
670                 /* See comment in __kmap_local_sched_out() */
671                 idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));
672                 addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
673                 kmap_pte = kmap_get_pte(addr, idx);
674                 set_pte_at(&init_mm, addr, kmap_pte, pteval);
675                 arch_kmap_local_post_map(addr, pteval);
676         }
677 }
678
679 void kmap_local_fork(struct task_struct *tsk)
680 {
681         if (WARN_ON_ONCE(tsk->kmap_ctrl.idx))
682                 memset(&tsk->kmap_ctrl, 0, sizeof(tsk->kmap_ctrl));
683 }
684
685 #endif
686
687 #if defined(HASHED_PAGE_VIRTUAL)
688
689 #define PA_HASH_ORDER   7
690
691 /*
692  * Describes one page->virtual association
693  */
694 struct page_address_map {
695         struct page *page;
696         void *virtual;
697         struct list_head list;
698 };
699
700 static struct page_address_map page_address_maps[LAST_PKMAP];
701
702 /*
703  * Hash table bucket
704  */
705 static struct page_address_slot {
706         struct list_head lh;                    /* List of page_address_maps */
707         spinlock_t lock;                        /* Protect this bucket's list */
708 } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
709
710 static struct page_address_slot *page_slot(const struct page *page)
711 {
712         return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
713 }
714
715 /**
716  * page_address - get the mapped virtual address of a page
717  * @page: &struct page to get the virtual address of
718  *
719  * Returns the page's virtual address.
720  */
721 void *page_address(const struct page *page)
722 {
723         unsigned long flags;
724         void *ret;
725         struct page_address_slot *pas;
726
727         if (!PageHighMem(page))
728                 return lowmem_page_address(page);
729
730         pas = page_slot(page);
731         ret = NULL;
732         spin_lock_irqsave(&pas->lock, flags);
733         if (!list_empty(&pas->lh)) {
734                 struct page_address_map *pam;
735
736                 list_for_each_entry(pam, &pas->lh, list) {
737                         if (pam->page == page) {
738                                 ret = pam->virtual;
739                                 break;
740                         }
741                 }
742         }
743
744         spin_unlock_irqrestore(&pas->lock, flags);
745         return ret;
746 }
747 EXPORT_SYMBOL(page_address);
748
749 /**
750  * set_page_address - set a page's virtual address
751  * @page: &struct page to set
752  * @virtual: virtual address to use
753  */
754 void set_page_address(struct page *page, void *virtual)
755 {
756         unsigned long flags;
757         struct page_address_slot *pas;
758         struct page_address_map *pam;
759
760         BUG_ON(!PageHighMem(page));
761
762         pas = page_slot(page);
763         if (virtual) {          /* Add */
764                 pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)];
765                 pam->page = page;
766                 pam->virtual = virtual;
767
768                 spin_lock_irqsave(&pas->lock, flags);
769                 list_add_tail(&pam->list, &pas->lh);
770                 spin_unlock_irqrestore(&pas->lock, flags);
771         } else {                /* Remove */
772                 spin_lock_irqsave(&pas->lock, flags);
773                 list_for_each_entry(pam, &pas->lh, list) {
774                         if (pam->page == page) {
775                                 list_del(&pam->list);
776                                 break;
777                         }
778                 }
779                 spin_unlock_irqrestore(&pas->lock, flags);
780         }
781
782         return;
783 }
784
785 void __init page_address_init(void)
786 {
787         int i;
788
789         for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
790                 INIT_LIST_HEAD(&page_address_htable[i].lh);
791                 spin_lock_init(&page_address_htable[i].lock);
792         }
793 }
794
795 #endif  /* defined(HASHED_PAGE_VIRTUAL) */