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