blob: 59db3223a5d62a9ea26f506ed3fd9fe6d54d2cf2 [file] [log] [blame]
Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
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>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040021#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#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>
Jason Wesseleac790052010-08-05 09:22:24 -050030#include <linux/kgdb.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <asm/tlbflush.h>
32
Peter Zijlstraa8e23a22010-10-27 15:32:57 -070033
34#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
35DEFINE_PER_CPU(int, __kmap_atomic_idx);
36#endif
37
Linus Torvalds1da177e2005-04-16 15:20:36 -070038/*
39 * Virtual_count is not a pure "count".
40 * 0 means that it is not mapped, and has not been mapped
41 * since a TLB flush - it is usable.
42 * 1 means that there are no users, but it has been mapped
43 * since the last TLB flush - so we can't use it.
44 * n means that there are (n-1) current users of it.
45 */
46#ifdef CONFIG_HIGHMEM
Al Viro260b2362005-10-21 03:22:44 -040047
Max Filippov15de36a2014-08-06 16:08:23 -070048/*
49 * Architecture with aliasing data cache may define the following family of
50 * helper functions in its asm/highmem.h to control cache color of virtual
51 * addresses where physical memory pages are mapped by kmap.
52 */
53#ifndef get_pkmap_color
54
55/*
56 * Determine color of virtual address where the page should be mapped.
57 */
58static inline unsigned int get_pkmap_color(struct page *page)
59{
60 return 0;
61}
62#define get_pkmap_color get_pkmap_color
63
64/*
65 * Get next index for mapping inside PKMAP region for page with given color.
66 */
67static inline unsigned int get_next_pkmap_nr(unsigned int color)
68{
69 static unsigned int last_pkmap_nr;
70
71 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
72 return last_pkmap_nr;
73}
74
75/*
76 * Determine if page index inside PKMAP region (pkmap_nr) of given color
77 * has wrapped around PKMAP region end. When this happens an attempt to
78 * flush all unused PKMAP slots is made.
79 */
80static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)
81{
82 return pkmap_nr == 0;
83}
84
85/*
86 * Get the number of PKMAP entries of the given color. If no free slot is
87 * found after checking that many entries, kmap will sleep waiting for
88 * someone to call kunmap and free PKMAP slot.
89 */
90static inline int get_pkmap_entries_count(unsigned int color)
91{
92 return LAST_PKMAP;
93}
94
95/*
96 * Get head of a wait queue for PKMAP entries of the given color.
97 * Wait queues for different mapping colors should be independent to avoid
98 * unnecessary wakeups caused by freeing of slots of other colors.
99 */
100static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
101{
102 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
103
104 return &pkmap_map_wait;
105}
106#endif
107
Christoph Lameterc1f60a52006-09-25 23:31:11 -0700108unsigned long totalhigh_pages __read_mostly;
David S. Millerdb7a94d2008-07-19 22:39:46 -0700109EXPORT_SYMBOL(totalhigh_pages);
Christoph Lameterc1f60a52006-09-25 23:31:11 -0700110
Peter Zijlstra3e4d3af2010-10-26 14:21:51 -0700111
Peter Zijlstra3e4d3af2010-10-26 14:21:51 -0700112EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);
113
Christoph Lameterc1f60a52006-09-25 23:31:11 -0700114unsigned int nr_free_highpages (void)
115{
Joonsoo Kim33499bf2016-05-19 17:12:26 -0700116 struct zone *zone;
Christoph Lameterc1f60a52006-09-25 23:31:11 -0700117 unsigned int pages = 0;
118
Joonsoo Kim33499bf2016-05-19 17:12:26 -0700119 for_each_populated_zone(zone) {
120 if (is_highmem(zone))
121 pages += zone_page_state(zone, NR_FREE_PAGES);
Mel Gorman2a1e2742007-07-17 04:03:12 -0700122 }
Christoph Lameterc1f60a52006-09-25 23:31:11 -0700123
124 return pages;
125}
126
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127static int pkmap_count[LAST_PKMAP];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
129
130pte_t * pkmap_page_table;
131
Nicolas Pitre3297e762009-03-04 22:49:41 -0500132/*
133 * Most architectures have no use for kmap_high_get(), so let's abstract
134 * the disabling of IRQ out of the locking in that case to save on a
135 * potential useless overhead.
136 */
137#ifdef ARCH_NEEDS_KMAP_HIGH_GET
138#define lock_kmap() spin_lock_irq(&kmap_lock)
139#define unlock_kmap() spin_unlock_irq(&kmap_lock)
140#define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags)
141#define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags)
142#else
143#define lock_kmap() spin_lock(&kmap_lock)
144#define unlock_kmap() spin_unlock(&kmap_lock)
145#define lock_kmap_any(flags) \
146 do { spin_lock(&kmap_lock); (void)(flags); } while (0)
147#define unlock_kmap_any(flags) \
148 do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
149#endif
150
Mel Gorman5a178112012-07-31 16:45:02 -0700151struct page *kmap_to_page(void *vaddr)
152{
153 unsigned long addr = (unsigned long)vaddr;
154
Will Deacon498c2282012-11-16 14:15:00 -0800155 if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
Joonsoo Kim4de22c02012-12-11 16:01:17 -0800156 int i = PKMAP_NR(addr);
Mel Gorman5a178112012-07-31 16:45:02 -0700157 return pte_page(pkmap_page_table[i]);
158 }
159
160 return virt_to_page(addr);
161}
Will Deaconf0263d22012-10-19 14:03:31 +0100162EXPORT_SYMBOL(kmap_to_page);
Mel Gorman5a178112012-07-31 16:45:02 -0700163
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164static void flush_all_zero_pkmaps(void)
165{
166 int i;
Nick Piggin5843d9a2008-08-01 03:15:21 +0200167 int need_flush = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
169 flush_cache_kmaps();
170
171 for (i = 0; i < LAST_PKMAP; i++) {
172 struct page *page;
173
174 /*
175 * zero means we don't have anything to do,
176 * >1 means that it is still in use. Only
177 * a count of 1 means that it is free but
178 * needs to be unmapped
179 */
180 if (pkmap_count[i] != 1)
181 continue;
182 pkmap_count[i] = 0;
183
184 /* sanity check */
Eric Sesterhenn75babca2006-04-02 13:47:35 +0200185 BUG_ON(pte_none(pkmap_page_table[i]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
187 /*
188 * Don't need an atomic fetch-and-clear op here;
189 * no-one has the page mapped, and cannot get at
190 * its virtual address (and hence PTE) without first
191 * getting the kmap_lock (which is held here).
192 * So no dangers, even with speculative execution.
193 */
194 page = pte_page(pkmap_page_table[i]);
Joonsoo Kimeb2db432012-12-11 16:01:24 -0800195 pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196
197 set_page_address(page, NULL);
Nick Piggin5843d9a2008-08-01 03:15:21 +0200198 need_flush = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 }
Nick Piggin5843d9a2008-08-01 03:15:21 +0200200 if (need_flush)
201 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202}
203
Randy Dunlap77f60782008-03-19 17:00:42 -0700204/**
205 * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings
206 */
Jeremy Fitzhardingece6234b2007-05-02 19:27:15 +0200207void kmap_flush_unused(void)
208{
Nicolas Pitre3297e762009-03-04 22:49:41 -0500209 lock_kmap();
Jeremy Fitzhardingece6234b2007-05-02 19:27:15 +0200210 flush_all_zero_pkmaps();
Nicolas Pitre3297e762009-03-04 22:49:41 -0500211 unlock_kmap();
Jeremy Fitzhardingece6234b2007-05-02 19:27:15 +0200212}
213
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214static inline unsigned long map_new_virtual(struct page *page)
215{
216 unsigned long vaddr;
217 int count;
Max Filippov15de36a2014-08-06 16:08:23 -0700218 unsigned int last_pkmap_nr;
219 unsigned int color = get_pkmap_color(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220
221start:
Max Filippov15de36a2014-08-06 16:08:23 -0700222 count = get_pkmap_entries_count(color);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 /* Find an empty entry */
224 for (;;) {
Max Filippov15de36a2014-08-06 16:08:23 -0700225 last_pkmap_nr = get_next_pkmap_nr(color);
226 if (no_more_pkmaps(last_pkmap_nr, color)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 flush_all_zero_pkmaps();
Max Filippov15de36a2014-08-06 16:08:23 -0700228 count = get_pkmap_entries_count(color);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 }
230 if (!pkmap_count[last_pkmap_nr])
231 break; /* Found a usable entry */
232 if (--count)
233 continue;
234
235 /*
236 * Sleep for somebody else to unmap their entries
237 */
238 {
239 DECLARE_WAITQUEUE(wait, current);
Max Filippov15de36a2014-08-06 16:08:23 -0700240 wait_queue_head_t *pkmap_map_wait =
241 get_pkmap_wait_queue_head(color);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242
243 __set_current_state(TASK_UNINTERRUPTIBLE);
Max Filippov15de36a2014-08-06 16:08:23 -0700244 add_wait_queue(pkmap_map_wait, &wait);
Nicolas Pitre3297e762009-03-04 22:49:41 -0500245 unlock_kmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 schedule();
Max Filippov15de36a2014-08-06 16:08:23 -0700247 remove_wait_queue(pkmap_map_wait, &wait);
Nicolas Pitre3297e762009-03-04 22:49:41 -0500248 lock_kmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249
250 /* Somebody else might have mapped it while we slept */
251 if (page_address(page))
252 return (unsigned long)page_address(page);
253
254 /* Re-start */
255 goto start;
256 }
257 }
258 vaddr = PKMAP_ADDR(last_pkmap_nr);
259 set_pte_at(&init_mm, vaddr,
260 &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
261
262 pkmap_count[last_pkmap_nr] = 1;
263 set_page_address(page, (void *)vaddr);
264
265 return vaddr;
266}
267
Randy Dunlap77f60782008-03-19 17:00:42 -0700268/**
269 * kmap_high - map a highmem page into memory
270 * @page: &struct page to map
271 *
272 * Returns the page's virtual memory address.
273 *
274 * We cannot call this from interrupts, as it may block.
275 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800276void *kmap_high(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277{
278 unsigned long vaddr;
279
280 /*
281 * For highmem pages, we can't trust "virtual" until
282 * after we have the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 */
Nicolas Pitre3297e762009-03-04 22:49:41 -0500284 lock_kmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 vaddr = (unsigned long)page_address(page);
286 if (!vaddr)
287 vaddr = map_new_virtual(page);
288 pkmap_count[PKMAP_NR(vaddr)]++;
Eric Sesterhenn75babca2006-04-02 13:47:35 +0200289 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
Nicolas Pitre3297e762009-03-04 22:49:41 -0500290 unlock_kmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 return (void*) vaddr;
292}
293
294EXPORT_SYMBOL(kmap_high);
295
Nicolas Pitre3297e762009-03-04 22:49:41 -0500296#ifdef ARCH_NEEDS_KMAP_HIGH_GET
297/**
298 * kmap_high_get - pin a highmem page into memory
299 * @page: &struct page to pin
300 *
301 * Returns the page's current virtual memory address, or NULL if no mapping
Uwe Kleine-König5e39df52010-01-25 21:38:09 +0100302 * exists. If and only if a non null address is returned then a
Nicolas Pitre3297e762009-03-04 22:49:41 -0500303 * matching call to kunmap_high() is necessary.
304 *
305 * This can be called from any context.
306 */
307void *kmap_high_get(struct page *page)
308{
309 unsigned long vaddr, flags;
310
311 lock_kmap_any(flags);
312 vaddr = (unsigned long)page_address(page);
313 if (vaddr) {
314 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
315 pkmap_count[PKMAP_NR(vaddr)]++;
316 }
317 unlock_kmap_any(flags);
318 return (void*) vaddr;
319}
320#endif
321
Randy Dunlap77f60782008-03-19 17:00:42 -0700322/**
Li Haifeng4e9dc5d2011-10-31 17:09:09 -0700323 * kunmap_high - unmap a highmem page into memory
Randy Dunlap77f60782008-03-19 17:00:42 -0700324 * @page: &struct page to unmap
Nicolas Pitre3297e762009-03-04 22:49:41 -0500325 *
326 * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
327 * only from user context.
Randy Dunlap77f60782008-03-19 17:00:42 -0700328 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800329void kunmap_high(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330{
331 unsigned long vaddr;
332 unsigned long nr;
Nicolas Pitre3297e762009-03-04 22:49:41 -0500333 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 int need_wakeup;
Max Filippov15de36a2014-08-06 16:08:23 -0700335 unsigned int color = get_pkmap_color(page);
336 wait_queue_head_t *pkmap_map_wait;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
Nicolas Pitre3297e762009-03-04 22:49:41 -0500338 lock_kmap_any(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 vaddr = (unsigned long)page_address(page);
Eric Sesterhenn75babca2006-04-02 13:47:35 +0200340 BUG_ON(!vaddr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 nr = PKMAP_NR(vaddr);
342
343 /*
344 * A count must never go down to zero
345 * without a TLB flush!
346 */
347 need_wakeup = 0;
348 switch (--pkmap_count[nr]) {
349 case 0:
350 BUG();
351 case 1:
352 /*
353 * Avoid an unnecessary wake_up() function call.
354 * The common case is pkmap_count[] == 1, but
355 * no waiters.
356 * The tasks queued in the wait-queue are guarded
357 * by both the lock in the wait-queue-head and by
358 * the kmap_lock. As the kmap_lock is held here,
359 * no need for the wait-queue-head's lock. Simply
360 * test if the queue is empty.
361 */
Max Filippov15de36a2014-08-06 16:08:23 -0700362 pkmap_map_wait = get_pkmap_wait_queue_head(color);
363 need_wakeup = waitqueue_active(pkmap_map_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 }
Nicolas Pitre3297e762009-03-04 22:49:41 -0500365 unlock_kmap_any(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366
367 /* do wake-up, if needed, race-free outside of the spin lock */
368 if (need_wakeup)
Max Filippov15de36a2014-08-06 16:08:23 -0700369 wake_up(pkmap_map_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370}
371
372EXPORT_SYMBOL(kunmap_high);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373#endif
374
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375#if defined(HASHED_PAGE_VIRTUAL)
376
377#define PA_HASH_ORDER 7
378
379/*
380 * Describes one page->virtual association
381 */
382struct page_address_map {
383 struct page *page;
384 void *virtual;
385 struct list_head list;
386};
387
Joonsoo Kima354e2c2012-12-11 16:01:23 -0800388static struct page_address_map page_address_maps[LAST_PKMAP];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389
390/*
391 * Hash table bucket
392 */
393static struct page_address_slot {
394 struct list_head lh; /* List of page_address_maps */
395 spinlock_t lock; /* Protect this bucket's list */
396} ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
397
Ian Campbellf9918792011-08-17 13:45:09 +0100398static struct page_address_slot *page_slot(const struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399{
400 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
401}
402
Randy Dunlap77f60782008-03-19 17:00:42 -0700403/**
404 * page_address - get the mapped virtual address of a page
405 * @page: &struct page to get the virtual address of
406 *
407 * Returns the page's virtual address.
408 */
Ian Campbellf9918792011-08-17 13:45:09 +0100409void *page_address(const struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410{
411 unsigned long flags;
412 void *ret;
413 struct page_address_slot *pas;
414
415 if (!PageHighMem(page))
416 return lowmem_page_address(page);
417
418 pas = page_slot(page);
419 ret = NULL;
420 spin_lock_irqsave(&pas->lock, flags);
421 if (!list_empty(&pas->lh)) {
422 struct page_address_map *pam;
423
424 list_for_each_entry(pam, &pas->lh, list) {
425 if (pam->page == page) {
426 ret = pam->virtual;
427 goto done;
428 }
429 }
430 }
431done:
432 spin_unlock_irqrestore(&pas->lock, flags);
433 return ret;
434}
435
436EXPORT_SYMBOL(page_address);
437
Randy Dunlap77f60782008-03-19 17:00:42 -0700438/**
439 * set_page_address - set a page's virtual address
440 * @page: &struct page to set
441 * @virtual: virtual address to use
442 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443void set_page_address(struct page *page, void *virtual)
444{
445 unsigned long flags;
446 struct page_address_slot *pas;
447 struct page_address_map *pam;
448
449 BUG_ON(!PageHighMem(page));
450
451 pas = page_slot(page);
452 if (virtual) { /* Add */
Joonsoo Kima354e2c2012-12-11 16:01:23 -0800453 pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 pam->page = page;
455 pam->virtual = virtual;
456
457 spin_lock_irqsave(&pas->lock, flags);
458 list_add_tail(&pam->list, &pas->lh);
459 spin_unlock_irqrestore(&pas->lock, flags);
460 } else { /* Remove */
461 spin_lock_irqsave(&pas->lock, flags);
462 list_for_each_entry(pam, &pas->lh, list) {
463 if (pam->page == page) {
464 list_del(&pam->list);
465 spin_unlock_irqrestore(&pas->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 goto done;
467 }
468 }
469 spin_unlock_irqrestore(&pas->lock, flags);
470 }
471done:
472 return;
473}
474
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475void __init page_address_init(void)
476{
477 int i;
478
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
480 INIT_LIST_HEAD(&page_address_htable[i].lh);
481 spin_lock_init(&page_address_htable[i].lock);
482 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483}
484
485#endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */