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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 | */ | |
54 | static 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 | */ | |
63 | static 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 | */ | |
76 | static 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 | */ | |
86 | static 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 | */ | |
96 | static 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 | ||
104 | atomic_long_t _totalhigh_pages __read_mostly; | |
105 | EXPORT_SYMBOL(_totalhigh_pages); | |
106 | ||
107 | unsigned 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 | ||
120 | static int pkmap_count[LAST_PKMAP]; | |
121 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); | |
122 | ||
123 | pte_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 | ||
144 | struct 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 | } | |
156 | EXPORT_SYMBOL(__kmap_to_page); | |
157 | ||
158 | static 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 | ||
198 | void __kmap_flush_unused(void) | |
199 | { | |
200 | lock_kmap(); | |
201 | flush_all_zero_pkmaps(); | |
202 | unlock_kmap(); | |
203 | } | |
204 | ||
205 | static 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 | ||
212 | start: | |
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 | */ | |
267 | void *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 | } | |
284 | EXPORT_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 | */ | |
297 | void *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 | */ | |
319 | void 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 | } | |
361 | EXPORT_SYMBOL(kunmap_high); | |
362 | ||
363 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | |
364 | void 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 | } | |
419 | EXPORT_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 | ||
437 | static inline int kmap_local_idx_push(void) | |
438 | { | |
439 | WARN_ON_ONCE(in_hardirq() && !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 | ||
445 | static inline int kmap_local_idx(void) | |
446 | { | |
447 | return current->kmap_ctrl.idx - 1; | |
448 | } | |
449 | ||
450 | static 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 | |
477 | static 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() */ | |
489 | static 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 | ||
500 | static inline int kmap_local_calc_idx(int idx) | |
501 | { | |
502 | return idx + KM_MAX_IDX * smp_processor_id(); | |
503 | } | |
504 | ||
505 | static pte_t *__kmap_pte; | |
506 | ||
507 | static pte_t *kmap_get_pte(unsigned long vaddr, int idx) | |
508 | { | |
509 | if (IS_ENABLED(CONFIG_KMAP_LOCAL_NON_LINEAR_PTE_ARRAY)) | |
510 | /* | |
511 | * Set by the arch if __kmap_pte[-idx] does not produce | |
512 | * the correct entry. | |
513 | */ | |
514 | return virt_to_kpte(vaddr); | |
515 | if (!__kmap_pte) | |
516 | __kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN)); | |
517 | return &__kmap_pte[-idx]; | |
518 | } | |
519 | ||
520 | void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot) | |
521 | { | |
522 | pte_t pteval, *kmap_pte; | |
523 | unsigned long vaddr; | |
524 | int idx; | |
525 | ||
526 | /* | |
527 | * Disable migration so resulting virtual address is stable | |
528 | * across preemption. | |
529 | */ | |
530 | migrate_disable(); | |
531 | preempt_disable(); | |
532 | idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn); | |
533 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
534 | kmap_pte = kmap_get_pte(vaddr, idx); | |
535 | BUG_ON(!pte_none(*kmap_pte)); | |
536 | pteval = pfn_pte(pfn, prot); | |
537 | arch_kmap_local_set_pte(&init_mm, vaddr, kmap_pte, pteval); | |
538 | arch_kmap_local_post_map(vaddr, pteval); | |
539 | current->kmap_ctrl.pteval[kmap_local_idx()] = pteval; | |
540 | preempt_enable(); | |
541 | ||
542 | return (void *)vaddr; | |
543 | } | |
544 | EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot); | |
545 | ||
546 | void *__kmap_local_page_prot(struct page *page, pgprot_t prot) | |
547 | { | |
548 | void *kmap; | |
549 | ||
550 | /* | |
551 | * To broaden the usage of the actual kmap_local() machinery always map | |
552 | * pages when debugging is enabled and the architecture has no problems | |
553 | * with alias mappings. | |
554 | */ | |
555 | if (!IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) && !PageHighMem(page)) | |
556 | return page_address(page); | |
557 | ||
558 | /* Try kmap_high_get() if architecture has it enabled */ | |
559 | kmap = arch_kmap_local_high_get(page); | |
560 | if (kmap) | |
561 | return kmap; | |
562 | ||
563 | return __kmap_local_pfn_prot(page_to_pfn(page), prot); | |
564 | } | |
565 | EXPORT_SYMBOL(__kmap_local_page_prot); | |
566 | ||
567 | void kunmap_local_indexed(void *vaddr) | |
568 | { | |
569 | unsigned long addr = (unsigned long) vaddr & PAGE_MASK; | |
570 | pte_t *kmap_pte; | |
571 | int idx; | |
572 | ||
573 | if (addr < __fix_to_virt(FIX_KMAP_END) || | |
574 | addr > __fix_to_virt(FIX_KMAP_BEGIN)) { | |
575 | if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP)) { | |
576 | /* This _should_ never happen! See above. */ | |
577 | WARN_ON_ONCE(1); | |
578 | return; | |
579 | } | |
580 | /* | |
581 | * Handle mappings which were obtained by kmap_high_get() | |
582 | * first as the virtual address of such mappings is below | |
583 | * PAGE_OFFSET. Warn for all other addresses which are in | |
584 | * the user space part of the virtual address space. | |
585 | */ | |
586 | if (!kmap_high_unmap_local(addr)) | |
587 | WARN_ON_ONCE(addr < PAGE_OFFSET); | |
588 | return; | |
589 | } | |
590 | ||
591 | preempt_disable(); | |
592 | idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr); | |
593 | WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); | |
594 | ||
595 | kmap_pte = kmap_get_pte(addr, idx); | |
596 | arch_kmap_local_pre_unmap(addr); | |
597 | pte_clear(&init_mm, addr, kmap_pte); | |
598 | arch_kmap_local_post_unmap(addr); | |
599 | current->kmap_ctrl.pteval[kmap_local_idx()] = __pte(0); | |
600 | kmap_local_idx_pop(); | |
601 | preempt_enable(); | |
602 | migrate_enable(); | |
603 | } | |
604 | EXPORT_SYMBOL(kunmap_local_indexed); | |
605 | ||
606 | /* | |
607 | * Invoked before switch_to(). This is safe even when during or after | |
608 | * clearing the maps an interrupt which needs a kmap_local happens because | |
609 | * the task::kmap_ctrl.idx is not modified by the unmapping code so a | |
610 | * nested kmap_local will use the next unused index and restore the index | |
611 | * on unmap. The already cleared kmaps of the outgoing task are irrelevant | |
612 | * because the interrupt context does not know about them. The same applies | |
613 | * when scheduling back in for an interrupt which happens before the | |
614 | * restore is complete. | |
615 | */ | |
616 | void __kmap_local_sched_out(void) | |
617 | { | |
618 | struct task_struct *tsk = current; | |
619 | pte_t *kmap_pte; | |
620 | int i; | |
621 | ||
622 | /* Clear kmaps */ | |
623 | for (i = 0; i < tsk->kmap_ctrl.idx; i++) { | |
624 | pte_t pteval = tsk->kmap_ctrl.pteval[i]; | |
625 | unsigned long addr; | |
626 | int idx; | |
627 | ||
628 | /* With debug all even slots are unmapped and act as guard */ | |
629 | if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { | |
630 | WARN_ON_ONCE(pte_val(pteval) != 0); | |
631 | continue; | |
632 | } | |
633 | if (WARN_ON_ONCE(pte_none(pteval))) | |
634 | continue; | |
635 | ||
636 | /* | |
637 | * This is a horrible hack for XTENSA to calculate the | |
638 | * coloured PTE index. Uses the PFN encoded into the pteval | |
639 | * and the map index calculation because the actual mapped | |
640 | * virtual address is not stored in task::kmap_ctrl. | |
641 | * For any sane architecture this is optimized out. | |
642 | */ | |
643 | idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); | |
644 | ||
645 | addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
646 | kmap_pte = kmap_get_pte(addr, idx); | |
647 | arch_kmap_local_pre_unmap(addr); | |
648 | pte_clear(&init_mm, addr, kmap_pte); | |
649 | arch_kmap_local_post_unmap(addr); | |
650 | } | |
651 | } | |
652 | ||
653 | void __kmap_local_sched_in(void) | |
654 | { | |
655 | struct task_struct *tsk = current; | |
656 | pte_t *kmap_pte; | |
657 | int i; | |
658 | ||
659 | /* Restore kmaps */ | |
660 | for (i = 0; i < tsk->kmap_ctrl.idx; i++) { | |
661 | pte_t pteval = tsk->kmap_ctrl.pteval[i]; | |
662 | unsigned long addr; | |
663 | int idx; | |
664 | ||
665 | /* With debug all even slots are unmapped and act as guard */ | |
666 | if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { | |
667 | WARN_ON_ONCE(pte_val(pteval) != 0); | |
668 | continue; | |
669 | } | |
670 | if (WARN_ON_ONCE(pte_none(pteval))) | |
671 | continue; | |
672 | ||
673 | /* See comment in __kmap_local_sched_out() */ | |
674 | idx = arch_kmap_local_map_idx(i, pte_pfn(pteval)); | |
675 | addr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
676 | kmap_pte = kmap_get_pte(addr, idx); | |
677 | set_pte_at(&init_mm, addr, kmap_pte, pteval); | |
678 | arch_kmap_local_post_map(addr, pteval); | |
679 | } | |
680 | } | |
681 | ||
682 | void kmap_local_fork(struct task_struct *tsk) | |
683 | { | |
684 | if (WARN_ON_ONCE(tsk->kmap_ctrl.idx)) | |
685 | memset(&tsk->kmap_ctrl, 0, sizeof(tsk->kmap_ctrl)); | |
686 | } | |
687 | ||
688 | #endif | |
689 | ||
690 | #if defined(HASHED_PAGE_VIRTUAL) | |
691 | ||
692 | #define PA_HASH_ORDER 7 | |
693 | ||
694 | /* | |
695 | * Describes one page->virtual association | |
696 | */ | |
697 | struct page_address_map { | |
698 | struct page *page; | |
699 | void *virtual; | |
700 | struct list_head list; | |
701 | }; | |
702 | ||
703 | static struct page_address_map page_address_maps[LAST_PKMAP]; | |
704 | ||
705 | /* | |
706 | * Hash table bucket | |
707 | */ | |
708 | static struct page_address_slot { | |
709 | struct list_head lh; /* List of page_address_maps */ | |
710 | spinlock_t lock; /* Protect this bucket's list */ | |
711 | } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER]; | |
712 | ||
713 | static struct page_address_slot *page_slot(const struct page *page) | |
714 | { | |
715 | return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)]; | |
716 | } | |
717 | ||
718 | /** | |
719 | * page_address - get the mapped virtual address of a page | |
720 | * @page: &struct page to get the virtual address of | |
721 | * | |
722 | * Returns the page's virtual address. | |
723 | */ | |
724 | void *page_address(const struct page *page) | |
725 | { | |
726 | unsigned long flags; | |
727 | void *ret; | |
728 | struct page_address_slot *pas; | |
729 | ||
730 | if (!PageHighMem(page)) | |
731 | return lowmem_page_address(page); | |
732 | ||
733 | pas = page_slot(page); | |
734 | ret = NULL; | |
735 | spin_lock_irqsave(&pas->lock, flags); | |
736 | if (!list_empty(&pas->lh)) { | |
737 | struct page_address_map *pam; | |
738 | ||
739 | list_for_each_entry(pam, &pas->lh, list) { | |
740 | if (pam->page == page) { | |
741 | ret = pam->virtual; | |
742 | goto done; | |
743 | } | |
744 | } | |
745 | } | |
746 | done: | |
747 | spin_unlock_irqrestore(&pas->lock, flags); | |
748 | return ret; | |
749 | } | |
750 | EXPORT_SYMBOL(page_address); | |
751 | ||
752 | /** | |
753 | * set_page_address - set a page's virtual address | |
754 | * @page: &struct page to set | |
755 | * @virtual: virtual address to use | |
756 | */ | |
757 | void set_page_address(struct page *page, void *virtual) | |
758 | { | |
759 | unsigned long flags; | |
760 | struct page_address_slot *pas; | |
761 | struct page_address_map *pam; | |
762 | ||
763 | BUG_ON(!PageHighMem(page)); | |
764 | ||
765 | pas = page_slot(page); | |
766 | if (virtual) { /* Add */ | |
767 | pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)]; | |
768 | pam->page = page; | |
769 | pam->virtual = virtual; | |
770 | ||
771 | spin_lock_irqsave(&pas->lock, flags); | |
772 | list_add_tail(&pam->list, &pas->lh); | |
773 | spin_unlock_irqrestore(&pas->lock, flags); | |
774 | } else { /* Remove */ | |
775 | spin_lock_irqsave(&pas->lock, flags); | |
776 | list_for_each_entry(pam, &pas->lh, list) { | |
777 | if (pam->page == page) { | |
778 | list_del(&pam->list); | |
779 | spin_unlock_irqrestore(&pas->lock, flags); | |
780 | goto done; | |
781 | } | |
782 | } | |
783 | spin_unlock_irqrestore(&pas->lock, flags); | |
784 | } | |
785 | done: | |
786 | return; | |
787 | } | |
788 | ||
789 | void __init page_address_init(void) | |
790 | { | |
791 | int i; | |
792 | ||
793 | for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) { | |
794 | INIT_LIST_HEAD(&page_address_htable[i].lh); | |
795 | spin_lock_init(&page_address_htable[i].lock); | |
796 | } | |
797 | } | |
798 | ||
799 | #endif /* defined(HASHED_PAGE_VIRTUAL) */ |