blob: 7a0aa1be4993521f7d55da731b3f69f8a59ea7c7 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * High memory handling common code and variables.
3 *
4 * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de
5 * Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de
6 *
7 *
8 * Redesigned the x86 32-bit VM architecture to deal with
9 * 64-bit physical space. With current x86 CPUs this
10 * means up to 64 Gigabytes physical RAM.
11 *
12 * Rewrote high memory support to move the page cache into
13 * high memory. Implemented permanent (schedulable) kmaps
14 * based on Linus' idea.
15 *
16 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
17 */
18
19#include <linux/mm.h>
20#include <linux/module.h>
21#include <linux/swap.h>
22#include <linux/bio.h>
23#include <linux/pagemap.h>
24#include <linux/mempool.h>
25#include <linux/blkdev.h>
26#include <linux/init.h>
27#include <linux/hash.h>
28#include <linux/highmem.h>
Jason Wesseleac790052010-08-05 09:22:24 -050029#include <linux/kgdb.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <asm/tlbflush.h>
31
Linus Torvalds1da177e2005-04-16 15:20:36 -070032/*
33 * Virtual_count is not a pure "count".
34 * 0 means that it is not mapped, and has not been mapped
35 * since a TLB flush - it is usable.
36 * 1 means that there are no users, but it has been mapped
37 * since the last TLB flush - so we can't use it.
38 * n means that there are (n-1) current users of it.
39 */
40#ifdef CONFIG_HIGHMEM
Al Viro260b2362005-10-21 03:22:44 -040041
Christoph Lameterc1f60a52006-09-25 23:31:11 -070042unsigned long totalhigh_pages __read_mostly;
David S. Millerdb7a94d2008-07-19 22:39:46 -070043EXPORT_SYMBOL(totalhigh_pages);
Christoph Lameterc1f60a52006-09-25 23:31:11 -070044
45unsigned int nr_free_highpages (void)
46{
47 pg_data_t *pgdat;
48 unsigned int pages = 0;
49
Mel Gorman2a1e2742007-07-17 04:03:12 -070050 for_each_online_pgdat(pgdat) {
Christoph Lameterd23ad422007-02-10 01:43:02 -080051 pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
52 NR_FREE_PAGES);
Mel Gorman2a1e2742007-07-17 04:03:12 -070053 if (zone_movable_is_highmem())
54 pages += zone_page_state(
55 &pgdat->node_zones[ZONE_MOVABLE],
56 NR_FREE_PAGES);
57 }
Christoph Lameterc1f60a52006-09-25 23:31:11 -070058
59 return pages;
60}
61
Linus Torvalds1da177e2005-04-16 15:20:36 -070062static int pkmap_count[LAST_PKMAP];
63static unsigned int last_pkmap_nr;
64static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
65
66pte_t * pkmap_page_table;
67
68static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
69
Nicolas Pitre3297e762009-03-04 22:49:41 -050070/*
71 * Most architectures have no use for kmap_high_get(), so let's abstract
72 * the disabling of IRQ out of the locking in that case to save on a
73 * potential useless overhead.
74 */
75#ifdef ARCH_NEEDS_KMAP_HIGH_GET
76#define lock_kmap() spin_lock_irq(&kmap_lock)
77#define unlock_kmap() spin_unlock_irq(&kmap_lock)
78#define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags)
79#define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags)
80#else
81#define lock_kmap() spin_lock(&kmap_lock)
82#define unlock_kmap() spin_unlock(&kmap_lock)
83#define lock_kmap_any(flags) \
84 do { spin_lock(&kmap_lock); (void)(flags); } while (0)
85#define unlock_kmap_any(flags) \
86 do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
87#endif
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089static void flush_all_zero_pkmaps(void)
90{
91 int i;
Nick Piggin5843d9a2008-08-01 03:15:21 +020092 int need_flush = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070093
94 flush_cache_kmaps();
95
96 for (i = 0; i < LAST_PKMAP; i++) {
97 struct page *page;
98
99 /*
100 * zero means we don't have anything to do,
101 * >1 means that it is still in use. Only
102 * a count of 1 means that it is free but
103 * needs to be unmapped
104 */
105 if (pkmap_count[i] != 1)
106 continue;
107 pkmap_count[i] = 0;
108
109 /* sanity check */
Eric Sesterhenn75babca2006-04-02 13:47:35 +0200110 BUG_ON(pte_none(pkmap_page_table[i]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111
112 /*
113 * Don't need an atomic fetch-and-clear op here;
114 * no-one has the page mapped, and cannot get at
115 * its virtual address (and hence PTE) without first
116 * getting the kmap_lock (which is held here).
117 * So no dangers, even with speculative execution.
118 */
119 page = pte_page(pkmap_page_table[i]);
120 pte_clear(&init_mm, (unsigned long)page_address(page),
121 &pkmap_page_table[i]);
122
123 set_page_address(page, NULL);
Nick Piggin5843d9a2008-08-01 03:15:21 +0200124 need_flush = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 }
Nick Piggin5843d9a2008-08-01 03:15:21 +0200126 if (need_flush)
127 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128}
129
Randy Dunlap77f60782008-03-19 17:00:42 -0700130/**
131 * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings
132 */
Jeremy Fitzhardingece6234b2007-05-02 19:27:15 +0200133void kmap_flush_unused(void)
134{
Nicolas Pitre3297e762009-03-04 22:49:41 -0500135 lock_kmap();
Jeremy Fitzhardingece6234b2007-05-02 19:27:15 +0200136 flush_all_zero_pkmaps();
Nicolas Pitre3297e762009-03-04 22:49:41 -0500137 unlock_kmap();
Jeremy Fitzhardingece6234b2007-05-02 19:27:15 +0200138}
139
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140static inline unsigned long map_new_virtual(struct page *page)
141{
142 unsigned long vaddr;
143 int count;
144
145start:
146 count = LAST_PKMAP;
147 /* Find an empty entry */
148 for (;;) {
149 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
150 if (!last_pkmap_nr) {
151 flush_all_zero_pkmaps();
152 count = LAST_PKMAP;
153 }
154 if (!pkmap_count[last_pkmap_nr])
155 break; /* Found a usable entry */
156 if (--count)
157 continue;
158
159 /*
160 * Sleep for somebody else to unmap their entries
161 */
162 {
163 DECLARE_WAITQUEUE(wait, current);
164
165 __set_current_state(TASK_UNINTERRUPTIBLE);
166 add_wait_queue(&pkmap_map_wait, &wait);
Nicolas Pitre3297e762009-03-04 22:49:41 -0500167 unlock_kmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 schedule();
169 remove_wait_queue(&pkmap_map_wait, &wait);
Nicolas Pitre3297e762009-03-04 22:49:41 -0500170 lock_kmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171
172 /* Somebody else might have mapped it while we slept */
173 if (page_address(page))
174 return (unsigned long)page_address(page);
175
176 /* Re-start */
177 goto start;
178 }
179 }
180 vaddr = PKMAP_ADDR(last_pkmap_nr);
181 set_pte_at(&init_mm, vaddr,
182 &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
183
184 pkmap_count[last_pkmap_nr] = 1;
185 set_page_address(page, (void *)vaddr);
186
187 return vaddr;
188}
189
Randy Dunlap77f60782008-03-19 17:00:42 -0700190/**
191 * kmap_high - map a highmem page into memory
192 * @page: &struct page to map
193 *
194 * Returns the page's virtual memory address.
195 *
196 * We cannot call this from interrupts, as it may block.
197 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800198void *kmap_high(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199{
200 unsigned long vaddr;
201
202 /*
203 * For highmem pages, we can't trust "virtual" until
204 * after we have the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 */
Nicolas Pitre3297e762009-03-04 22:49:41 -0500206 lock_kmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 vaddr = (unsigned long)page_address(page);
208 if (!vaddr)
209 vaddr = map_new_virtual(page);
210 pkmap_count[PKMAP_NR(vaddr)]++;
Eric Sesterhenn75babca2006-04-02 13:47:35 +0200211 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
Nicolas Pitre3297e762009-03-04 22:49:41 -0500212 unlock_kmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 return (void*) vaddr;
214}
215
216EXPORT_SYMBOL(kmap_high);
217
Nicolas Pitre3297e762009-03-04 22:49:41 -0500218#ifdef ARCH_NEEDS_KMAP_HIGH_GET
219/**
220 * kmap_high_get - pin a highmem page into memory
221 * @page: &struct page to pin
222 *
223 * Returns the page's current virtual memory address, or NULL if no mapping
Uwe Kleine-König5e39df52010-01-25 21:38:09 +0100224 * exists. If and only if a non null address is returned then a
Nicolas Pitre3297e762009-03-04 22:49:41 -0500225 * matching call to kunmap_high() is necessary.
226 *
227 * This can be called from any context.
228 */
229void *kmap_high_get(struct page *page)
230{
231 unsigned long vaddr, flags;
232
233 lock_kmap_any(flags);
234 vaddr = (unsigned long)page_address(page);
235 if (vaddr) {
236 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
237 pkmap_count[PKMAP_NR(vaddr)]++;
238 }
239 unlock_kmap_any(flags);
240 return (void*) vaddr;
241}
242#endif
243
Randy Dunlap77f60782008-03-19 17:00:42 -0700244/**
245 * kunmap_high - map a highmem page into memory
246 * @page: &struct page to unmap
Nicolas Pitre3297e762009-03-04 22:49:41 -0500247 *
248 * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
249 * only from user context.
Randy Dunlap77f60782008-03-19 17:00:42 -0700250 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800251void kunmap_high(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252{
253 unsigned long vaddr;
254 unsigned long nr;
Nicolas Pitre3297e762009-03-04 22:49:41 -0500255 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 int need_wakeup;
257
Nicolas Pitre3297e762009-03-04 22:49:41 -0500258 lock_kmap_any(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 vaddr = (unsigned long)page_address(page);
Eric Sesterhenn75babca2006-04-02 13:47:35 +0200260 BUG_ON(!vaddr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 nr = PKMAP_NR(vaddr);
262
263 /*
264 * A count must never go down to zero
265 * without a TLB flush!
266 */
267 need_wakeup = 0;
268 switch (--pkmap_count[nr]) {
269 case 0:
270 BUG();
271 case 1:
272 /*
273 * Avoid an unnecessary wake_up() function call.
274 * The common case is pkmap_count[] == 1, but
275 * no waiters.
276 * The tasks queued in the wait-queue are guarded
277 * by both the lock in the wait-queue-head and by
278 * the kmap_lock. As the kmap_lock is held here,
279 * no need for the wait-queue-head's lock. Simply
280 * test if the queue is empty.
281 */
282 need_wakeup = waitqueue_active(&pkmap_map_wait);
283 }
Nicolas Pitre3297e762009-03-04 22:49:41 -0500284 unlock_kmap_any(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
286 /* do wake-up, if needed, race-free outside of the spin lock */
287 if (need_wakeup)
288 wake_up(&pkmap_map_wait);
289}
290
291EXPORT_SYMBOL(kunmap_high);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292#endif
293
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294#if defined(HASHED_PAGE_VIRTUAL)
295
296#define PA_HASH_ORDER 7
297
298/*
299 * Describes one page->virtual association
300 */
301struct page_address_map {
302 struct page *page;
303 void *virtual;
304 struct list_head list;
305};
306
307/*
308 * page_address_map freelist, allocated from page_address_maps.
309 */
310static struct list_head page_address_pool; /* freelist */
311static spinlock_t pool_lock; /* protects page_address_pool */
312
313/*
314 * Hash table bucket
315 */
316static struct page_address_slot {
317 struct list_head lh; /* List of page_address_maps */
318 spinlock_t lock; /* Protect this bucket's list */
319} ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
320
321static struct page_address_slot *page_slot(struct page *page)
322{
323 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
324}
325
Randy Dunlap77f60782008-03-19 17:00:42 -0700326/**
327 * page_address - get the mapped virtual address of a page
328 * @page: &struct page to get the virtual address of
329 *
330 * Returns the page's virtual address.
331 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332void *page_address(struct page *page)
333{
334 unsigned long flags;
335 void *ret;
336 struct page_address_slot *pas;
337
338 if (!PageHighMem(page))
339 return lowmem_page_address(page);
340
341 pas = page_slot(page);
342 ret = NULL;
343 spin_lock_irqsave(&pas->lock, flags);
344 if (!list_empty(&pas->lh)) {
345 struct page_address_map *pam;
346
347 list_for_each_entry(pam, &pas->lh, list) {
348 if (pam->page == page) {
349 ret = pam->virtual;
350 goto done;
351 }
352 }
353 }
354done:
355 spin_unlock_irqrestore(&pas->lock, flags);
356 return ret;
357}
358
359EXPORT_SYMBOL(page_address);
360
Randy Dunlap77f60782008-03-19 17:00:42 -0700361/**
362 * set_page_address - set a page's virtual address
363 * @page: &struct page to set
364 * @virtual: virtual address to use
365 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366void set_page_address(struct page *page, void *virtual)
367{
368 unsigned long flags;
369 struct page_address_slot *pas;
370 struct page_address_map *pam;
371
372 BUG_ON(!PageHighMem(page));
373
374 pas = page_slot(page);
375 if (virtual) { /* Add */
376 BUG_ON(list_empty(&page_address_pool));
377
378 spin_lock_irqsave(&pool_lock, flags);
379 pam = list_entry(page_address_pool.next,
380 struct page_address_map, list);
381 list_del(&pam->list);
382 spin_unlock_irqrestore(&pool_lock, flags);
383
384 pam->page = page;
385 pam->virtual = virtual;
386
387 spin_lock_irqsave(&pas->lock, flags);
388 list_add_tail(&pam->list, &pas->lh);
389 spin_unlock_irqrestore(&pas->lock, flags);
390 } else { /* Remove */
391 spin_lock_irqsave(&pas->lock, flags);
392 list_for_each_entry(pam, &pas->lh, list) {
393 if (pam->page == page) {
394 list_del(&pam->list);
395 spin_unlock_irqrestore(&pas->lock, flags);
396 spin_lock_irqsave(&pool_lock, flags);
397 list_add_tail(&pam->list, &page_address_pool);
398 spin_unlock_irqrestore(&pool_lock, flags);
399 goto done;
400 }
401 }
402 spin_unlock_irqrestore(&pas->lock, flags);
403 }
404done:
405 return;
406}
407
408static struct page_address_map page_address_maps[LAST_PKMAP];
409
410void __init page_address_init(void)
411{
412 int i;
413
414 INIT_LIST_HEAD(&page_address_pool);
415 for (i = 0; i < ARRAY_SIZE(page_address_maps); i++)
416 list_add(&page_address_maps[i].list, &page_address_pool);
417 for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
418 INIT_LIST_HEAD(&page_address_htable[i].lh);
419 spin_lock_init(&page_address_htable[i].lock);
420 }
421 spin_lock_init(&pool_lock);
422}
423
424#endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */
Akinobu Mitaf4112de2009-03-31 15:23:25 -0700425
Akinobu Mitaff3d58c2010-05-24 14:32:46 -0700426#ifdef CONFIG_DEBUG_HIGHMEM
Akinobu Mitaf4112de2009-03-31 15:23:25 -0700427
428void debug_kmap_atomic(enum km_type type)
429{
Soeren Sandmann5ebd4c22009-10-28 18:55:36 +0100430 static int warn_count = 10;
Akinobu Mitaf4112de2009-03-31 15:23:25 -0700431
Soeren Sandmann5ebd4c22009-10-28 18:55:36 +0100432 if (unlikely(warn_count < 0))
Akinobu Mitaf4112de2009-03-31 15:23:25 -0700433 return;
434
435 if (unlikely(in_interrupt())) {
Soeren Sandmannd4515642009-10-28 18:56:35 +0100436 if (in_nmi()) {
437 if (type != KM_NMI && type != KM_NMI_PTE) {
438 WARN_ON(1);
439 warn_count--;
440 }
441 } else if (in_irq()) {
Akinobu Mitaf4112de2009-03-31 15:23:25 -0700442 if (type != KM_IRQ0 && type != KM_IRQ1 &&
443 type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
Soeren Sandmannd4515642009-10-28 18:56:35 +0100444 type != KM_BOUNCE_READ && type != KM_IRQ_PTE) {
Akinobu Mitaf4112de2009-03-31 15:23:25 -0700445 WARN_ON(1);
446 warn_count--;
447 }
448 } else if (!irqs_disabled()) { /* softirq */
449 if (type != KM_IRQ0 && type != KM_IRQ1 &&
450 type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
451 type != KM_SKB_SUNRPC_DATA &&
452 type != KM_SKB_DATA_SOFTIRQ &&
453 type != KM_BOUNCE_READ) {
454 WARN_ON(1);
455 warn_count--;
456 }
457 }
458 }
459
460 if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
Soeren Sandmannd4515642009-10-28 18:56:35 +0100461 type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ ||
462 type == KM_IRQ_PTE || type == KM_NMI ||
463 type == KM_NMI_PTE ) {
Akinobu Mitaf4112de2009-03-31 15:23:25 -0700464 if (!irqs_disabled()) {
465 WARN_ON(1);
466 warn_count--;
467 }
468 } else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
469 if (irq_count() == 0 && !irqs_disabled()) {
470 WARN_ON(1);
471 warn_count--;
472 }
473 }
Jason Wesseleac790052010-08-05 09:22:24 -0500474#ifdef CONFIG_KGDB_KDB
475 if (unlikely(type == KM_KDB && atomic_read(&kgdb_active) == -1)) {
476 WARN_ON(1);
477 warn_count--;
478 }
479#endif /* CONFIG_KGDB_KDB */
Akinobu Mitaf4112de2009-03-31 15:23:25 -0700480}
481
482#endif