]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - mm/highmem.c
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux...
[mirror_ubuntu-bionic-kernel.git] / mm / highmem.c
1 /*
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>
29 #include <linux/blktrace_api.h>
30 #include <asm/tlbflush.h>
31
32 /*
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
41
42 unsigned long totalhigh_pages __read_mostly;
43 EXPORT_SYMBOL(totalhigh_pages);
44
45 unsigned int nr_free_highpages (void)
46 {
47 pg_data_t *pgdat;
48 unsigned int pages = 0;
49
50 for_each_online_pgdat(pgdat) {
51 pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
52 NR_FREE_PAGES);
53 if (zone_movable_is_highmem())
54 pages += zone_page_state(
55 &pgdat->node_zones[ZONE_MOVABLE],
56 NR_FREE_PAGES);
57 }
58
59 return pages;
60 }
61
62 static int pkmap_count[LAST_PKMAP];
63 static unsigned int last_pkmap_nr;
64 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
65
66 pte_t * pkmap_page_table;
67
68 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
69
70 /*
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
89 static void flush_all_zero_pkmaps(void)
90 {
91 int i;
92 int need_flush = 0;
93
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 */
110 BUG_ON(pte_none(pkmap_page_table[i]));
111
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);
124 need_flush = 1;
125 }
126 if (need_flush)
127 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
128 }
129
130 /**
131 * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings
132 */
133 void kmap_flush_unused(void)
134 {
135 lock_kmap();
136 flush_all_zero_pkmaps();
137 unlock_kmap();
138 }
139
140 static inline unsigned long map_new_virtual(struct page *page)
141 {
142 unsigned long vaddr;
143 int count;
144
145 start:
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);
167 unlock_kmap();
168 schedule();
169 remove_wait_queue(&pkmap_map_wait, &wait);
170 lock_kmap();
171
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
190 /**
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 */
198 void *kmap_high(struct page *page)
199 {
200 unsigned long vaddr;
201
202 /*
203 * For highmem pages, we can't trust "virtual" until
204 * after we have the lock.
205 */
206 lock_kmap();
207 vaddr = (unsigned long)page_address(page);
208 if (!vaddr)
209 vaddr = map_new_virtual(page);
210 pkmap_count[PKMAP_NR(vaddr)]++;
211 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
212 unlock_kmap();
213 return (void*) vaddr;
214 }
215
216 EXPORT_SYMBOL(kmap_high);
217
218 #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
224 * exists. When and only when a non null address is returned then a
225 * matching call to kunmap_high() is necessary.
226 *
227 * This can be called from any context.
228 */
229 void *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
244 /**
245 * kunmap_high - map a highmem page into memory
246 * @page: &struct page to unmap
247 *
248 * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
249 * only from user context.
250 */
251 void kunmap_high(struct page *page)
252 {
253 unsigned long vaddr;
254 unsigned long nr;
255 unsigned long flags;
256 int need_wakeup;
257
258 lock_kmap_any(flags);
259 vaddr = (unsigned long)page_address(page);
260 BUG_ON(!vaddr);
261 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 }
284 unlock_kmap_any(flags);
285
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
291 EXPORT_SYMBOL(kunmap_high);
292 #endif
293
294 #if defined(HASHED_PAGE_VIRTUAL)
295
296 #define PA_HASH_ORDER 7
297
298 /*
299 * Describes one page->virtual association
300 */
301 struct 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 */
310 static struct list_head page_address_pool; /* freelist */
311 static spinlock_t pool_lock; /* protects page_address_pool */
312
313 /*
314 * Hash table bucket
315 */
316 static 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
321 static struct page_address_slot *page_slot(struct page *page)
322 {
323 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
324 }
325
326 /**
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 */
332 void *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 }
354 done:
355 spin_unlock_irqrestore(&pas->lock, flags);
356 return ret;
357 }
358
359 EXPORT_SYMBOL(page_address);
360
361 /**
362 * set_page_address - set a page's virtual address
363 * @page: &struct page to set
364 * @virtual: virtual address to use
365 */
366 void 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 }
404 done:
405 return;
406 }
407
408 static struct page_address_map page_address_maps[LAST_PKMAP];
409
410 void __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) */
425
426 #if defined(CONFIG_DEBUG_HIGHMEM) && defined(CONFIG_TRACE_IRQFLAGS_SUPPORT)
427
428 void debug_kmap_atomic(enum km_type type)
429 {
430 static unsigned warn_count = 10;
431
432 if (unlikely(warn_count == 0))
433 return;
434
435 if (unlikely(in_interrupt())) {
436 if (in_irq()) {
437 if (type != KM_IRQ0 && type != KM_IRQ1 &&
438 type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
439 type != KM_BOUNCE_READ) {
440 WARN_ON(1);
441 warn_count--;
442 }
443 } else if (!irqs_disabled()) { /* softirq */
444 if (type != KM_IRQ0 && type != KM_IRQ1 &&
445 type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
446 type != KM_SKB_SUNRPC_DATA &&
447 type != KM_SKB_DATA_SOFTIRQ &&
448 type != KM_BOUNCE_READ) {
449 WARN_ON(1);
450 warn_count--;
451 }
452 }
453 }
454
455 if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
456 type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ) {
457 if (!irqs_disabled()) {
458 WARN_ON(1);
459 warn_count--;
460 }
461 } else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
462 if (irq_count() == 0 && !irqs_disabled()) {
463 WARN_ON(1);
464 warn_count--;
465 }
466 }
467 }
468
469 #endif