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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 <asm/tlbflush.h> | |
30 | ||
31 | /* | |
32 | * Virtual_count is not a pure "count". | |
33 | * 0 means that it is not mapped, and has not been mapped | |
34 | * since a TLB flush - it is usable. | |
35 | * 1 means that there are no users, but it has been mapped | |
36 | * since the last TLB flush - so we can't use it. | |
37 | * n means that there are (n-1) current users of it. | |
38 | */ | |
39 | #ifdef CONFIG_HIGHMEM | |
40 | ||
41 | unsigned long totalhigh_pages __read_mostly; | |
42 | EXPORT_SYMBOL(totalhigh_pages); | |
43 | ||
44 | unsigned int nr_free_highpages (void) | |
45 | { | |
46 | pg_data_t *pgdat; | |
47 | unsigned int pages = 0; | |
48 | ||
49 | for_each_online_pgdat(pgdat) { | |
50 | pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM], | |
51 | NR_FREE_PAGES); | |
52 | if (zone_movable_is_highmem()) | |
53 | pages += zone_page_state( | |
54 | &pgdat->node_zones[ZONE_MOVABLE], | |
55 | NR_FREE_PAGES); | |
56 | } | |
57 | ||
58 | return pages; | |
59 | } | |
60 | ||
61 | static int pkmap_count[LAST_PKMAP]; | |
62 | static unsigned int last_pkmap_nr; | |
63 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); | |
64 | ||
65 | pte_t * pkmap_page_table; | |
66 | ||
67 | static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); | |
68 | ||
69 | /* | |
70 | * Most architectures have no use for kmap_high_get(), so let's abstract | |
71 | * the disabling of IRQ out of the locking in that case to save on a | |
72 | * potential useless overhead. | |
73 | */ | |
74 | #ifdef ARCH_NEEDS_KMAP_HIGH_GET | |
75 | #define lock_kmap() spin_lock_irq(&kmap_lock) | |
76 | #define unlock_kmap() spin_unlock_irq(&kmap_lock) | |
77 | #define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags) | |
78 | #define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags) | |
79 | #else | |
80 | #define lock_kmap() spin_lock(&kmap_lock) | |
81 | #define unlock_kmap() spin_unlock(&kmap_lock) | |
82 | #define lock_kmap_any(flags) \ | |
83 | do { spin_lock(&kmap_lock); (void)(flags); } while (0) | |
84 | #define unlock_kmap_any(flags) \ | |
85 | do { spin_unlock(&kmap_lock); (void)(flags); } while (0) | |
86 | #endif | |
87 | ||
88 | static void flush_all_zero_pkmaps(void) | |
89 | { | |
90 | int i; | |
91 | int need_flush = 0; | |
92 | ||
93 | flush_cache_kmaps(); | |
94 | ||
95 | for (i = 0; i < LAST_PKMAP; i++) { | |
96 | struct page *page; | |
97 | ||
98 | /* | |
99 | * zero means we don't have anything to do, | |
100 | * >1 means that it is still in use. Only | |
101 | * a count of 1 means that it is free but | |
102 | * needs to be unmapped | |
103 | */ | |
104 | if (pkmap_count[i] != 1) | |
105 | continue; | |
106 | pkmap_count[i] = 0; | |
107 | ||
108 | /* sanity check */ | |
109 | BUG_ON(pte_none(pkmap_page_table[i])); | |
110 | ||
111 | /* | |
112 | * Don't need an atomic fetch-and-clear op here; | |
113 | * no-one has the page mapped, and cannot get at | |
114 | * its virtual address (and hence PTE) without first | |
115 | * getting the kmap_lock (which is held here). | |
116 | * So no dangers, even with speculative execution. | |
117 | */ | |
118 | page = pte_page(pkmap_page_table[i]); | |
119 | pte_clear(&init_mm, (unsigned long)page_address(page), | |
120 | &pkmap_page_table[i]); | |
121 | ||
122 | set_page_address(page, NULL); | |
123 | need_flush = 1; | |
124 | } | |
125 | if (need_flush) | |
126 | flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP)); | |
127 | } | |
128 | ||
129 | /** | |
130 | * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings | |
131 | */ | |
132 | void kmap_flush_unused(void) | |
133 | { | |
134 | lock_kmap(); | |
135 | flush_all_zero_pkmaps(); | |
136 | unlock_kmap(); | |
137 | } | |
138 | ||
139 | static inline unsigned long map_new_virtual(struct page *page) | |
140 | { | |
141 | unsigned long vaddr; | |
142 | int count; | |
143 | ||
144 | start: | |
145 | count = LAST_PKMAP; | |
146 | /* Find an empty entry */ | |
147 | for (;;) { | |
148 | last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK; | |
149 | if (!last_pkmap_nr) { | |
150 | flush_all_zero_pkmaps(); | |
151 | count = LAST_PKMAP; | |
152 | } | |
153 | if (!pkmap_count[last_pkmap_nr]) | |
154 | break; /* Found a usable entry */ | |
155 | if (--count) | |
156 | continue; | |
157 | ||
158 | /* | |
159 | * Sleep for somebody else to unmap their entries | |
160 | */ | |
161 | { | |
162 | DECLARE_WAITQUEUE(wait, current); | |
163 | ||
164 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
165 | add_wait_queue(&pkmap_map_wait, &wait); | |
166 | unlock_kmap(); | |
167 | schedule(); | |
168 | remove_wait_queue(&pkmap_map_wait, &wait); | |
169 | lock_kmap(); | |
170 | ||
171 | /* Somebody else might have mapped it while we slept */ | |
172 | if (page_address(page)) | |
173 | return (unsigned long)page_address(page); | |
174 | ||
175 | /* Re-start */ | |
176 | goto start; | |
177 | } | |
178 | } | |
179 | vaddr = PKMAP_ADDR(last_pkmap_nr); | |
180 | set_pte_at(&init_mm, vaddr, | |
181 | &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot)); | |
182 | ||
183 | pkmap_count[last_pkmap_nr] = 1; | |
184 | set_page_address(page, (void *)vaddr); | |
185 | ||
186 | return vaddr; | |
187 | } | |
188 | ||
189 | /** | |
190 | * kmap_high - map a highmem page into memory | |
191 | * @page: &struct page to map | |
192 | * | |
193 | * Returns the page's virtual memory address. | |
194 | * | |
195 | * We cannot call this from interrupts, as it may block. | |
196 | */ | |
197 | void *kmap_high(struct page *page) | |
198 | { | |
199 | unsigned long vaddr; | |
200 | ||
201 | /* | |
202 | * For highmem pages, we can't trust "virtual" until | |
203 | * after we have the lock. | |
204 | */ | |
205 | lock_kmap(); | |
206 | vaddr = (unsigned long)page_address(page); | |
207 | if (!vaddr) | |
208 | vaddr = map_new_virtual(page); | |
209 | pkmap_count[PKMAP_NR(vaddr)]++; | |
210 | BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2); | |
211 | unlock_kmap(); | |
212 | return (void*) vaddr; | |
213 | } | |
214 | ||
215 | EXPORT_SYMBOL(kmap_high); | |
216 | ||
217 | #ifdef ARCH_NEEDS_KMAP_HIGH_GET | |
218 | /** | |
219 | * kmap_high_get - pin a highmem page into memory | |
220 | * @page: &struct page to pin | |
221 | * | |
222 | * Returns the page's current virtual memory address, or NULL if no mapping | |
223 | * exists. When and only when a non null address is returned then a | |
224 | * matching call to kunmap_high() is necessary. | |
225 | * | |
226 | * This can be called from any context. | |
227 | */ | |
228 | void *kmap_high_get(struct page *page) | |
229 | { | |
230 | unsigned long vaddr, flags; | |
231 | ||
232 | lock_kmap_any(flags); | |
233 | vaddr = (unsigned long)page_address(page); | |
234 | if (vaddr) { | |
235 | BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1); | |
236 | pkmap_count[PKMAP_NR(vaddr)]++; | |
237 | } | |
238 | unlock_kmap_any(flags); | |
239 | return (void*) vaddr; | |
240 | } | |
241 | #endif | |
242 | ||
243 | /** | |
244 | * kunmap_high - map a highmem page into memory | |
245 | * @page: &struct page to unmap | |
246 | * | |
247 | * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called | |
248 | * only from user context. | |
249 | */ | |
250 | void kunmap_high(struct page *page) | |
251 | { | |
252 | unsigned long vaddr; | |
253 | unsigned long nr; | |
254 | unsigned long flags; | |
255 | int need_wakeup; | |
256 | ||
257 | lock_kmap_any(flags); | |
258 | vaddr = (unsigned long)page_address(page); | |
259 | BUG_ON(!vaddr); | |
260 | nr = PKMAP_NR(vaddr); | |
261 | ||
262 | /* | |
263 | * A count must never go down to zero | |
264 | * without a TLB flush! | |
265 | */ | |
266 | need_wakeup = 0; | |
267 | switch (--pkmap_count[nr]) { | |
268 | case 0: | |
269 | BUG(); | |
270 | case 1: | |
271 | /* | |
272 | * Avoid an unnecessary wake_up() function call. | |
273 | * The common case is pkmap_count[] == 1, but | |
274 | * no waiters. | |
275 | * The tasks queued in the wait-queue are guarded | |
276 | * by both the lock in the wait-queue-head and by | |
277 | * the kmap_lock. As the kmap_lock is held here, | |
278 | * no need for the wait-queue-head's lock. Simply | |
279 | * test if the queue is empty. | |
280 | */ | |
281 | need_wakeup = waitqueue_active(&pkmap_map_wait); | |
282 | } | |
283 | unlock_kmap_any(flags); | |
284 | ||
285 | /* do wake-up, if needed, race-free outside of the spin lock */ | |
286 | if (need_wakeup) | |
287 | wake_up(&pkmap_map_wait); | |
288 | } | |
289 | ||
290 | EXPORT_SYMBOL(kunmap_high); | |
291 | #endif | |
292 | ||
293 | #if defined(HASHED_PAGE_VIRTUAL) | |
294 | ||
295 | #define PA_HASH_ORDER 7 | |
296 | ||
297 | /* | |
298 | * Describes one page->virtual association | |
299 | */ | |
300 | struct page_address_map { | |
301 | struct page *page; | |
302 | void *virtual; | |
303 | struct list_head list; | |
304 | }; | |
305 | ||
306 | /* | |
307 | * page_address_map freelist, allocated from page_address_maps. | |
308 | */ | |
309 | static struct list_head page_address_pool; /* freelist */ | |
310 | static spinlock_t pool_lock; /* protects page_address_pool */ | |
311 | ||
312 | /* | |
313 | * Hash table bucket | |
314 | */ | |
315 | static struct page_address_slot { | |
316 | struct list_head lh; /* List of page_address_maps */ | |
317 | spinlock_t lock; /* Protect this bucket's list */ | |
318 | } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER]; | |
319 | ||
320 | static struct page_address_slot *page_slot(struct page *page) | |
321 | { | |
322 | return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)]; | |
323 | } | |
324 | ||
325 | /** | |
326 | * page_address - get the mapped virtual address of a page | |
327 | * @page: &struct page to get the virtual address of | |
328 | * | |
329 | * Returns the page's virtual address. | |
330 | */ | |
331 | void *page_address(struct page *page) | |
332 | { | |
333 | unsigned long flags; | |
334 | void *ret; | |
335 | struct page_address_slot *pas; | |
336 | ||
337 | if (!PageHighMem(page)) | |
338 | return lowmem_page_address(page); | |
339 | ||
340 | pas = page_slot(page); | |
341 | ret = NULL; | |
342 | spin_lock_irqsave(&pas->lock, flags); | |
343 | if (!list_empty(&pas->lh)) { | |
344 | struct page_address_map *pam; | |
345 | ||
346 | list_for_each_entry(pam, &pas->lh, list) { | |
347 | if (pam->page == page) { | |
348 | ret = pam->virtual; | |
349 | goto done; | |
350 | } | |
351 | } | |
352 | } | |
353 | done: | |
354 | spin_unlock_irqrestore(&pas->lock, flags); | |
355 | return ret; | |
356 | } | |
357 | ||
358 | EXPORT_SYMBOL(page_address); | |
359 | ||
360 | /** | |
361 | * set_page_address - set a page's virtual address | |
362 | * @page: &struct page to set | |
363 | * @virtual: virtual address to use | |
364 | */ | |
365 | void set_page_address(struct page *page, void *virtual) | |
366 | { | |
367 | unsigned long flags; | |
368 | struct page_address_slot *pas; | |
369 | struct page_address_map *pam; | |
370 | ||
371 | BUG_ON(!PageHighMem(page)); | |
372 | ||
373 | pas = page_slot(page); | |
374 | if (virtual) { /* Add */ | |
375 | BUG_ON(list_empty(&page_address_pool)); | |
376 | ||
377 | spin_lock_irqsave(&pool_lock, flags); | |
378 | pam = list_entry(page_address_pool.next, | |
379 | struct page_address_map, list); | |
380 | list_del(&pam->list); | |
381 | spin_unlock_irqrestore(&pool_lock, flags); | |
382 | ||
383 | pam->page = page; | |
384 | pam->virtual = virtual; | |
385 | ||
386 | spin_lock_irqsave(&pas->lock, flags); | |
387 | list_add_tail(&pam->list, &pas->lh); | |
388 | spin_unlock_irqrestore(&pas->lock, flags); | |
389 | } else { /* Remove */ | |
390 | spin_lock_irqsave(&pas->lock, flags); | |
391 | list_for_each_entry(pam, &pas->lh, list) { | |
392 | if (pam->page == page) { | |
393 | list_del(&pam->list); | |
394 | spin_unlock_irqrestore(&pas->lock, flags); | |
395 | spin_lock_irqsave(&pool_lock, flags); | |
396 | list_add_tail(&pam->list, &page_address_pool); | |
397 | spin_unlock_irqrestore(&pool_lock, flags); | |
398 | goto done; | |
399 | } | |
400 | } | |
401 | spin_unlock_irqrestore(&pas->lock, flags); | |
402 | } | |
403 | done: | |
404 | return; | |
405 | } | |
406 | ||
407 | static struct page_address_map page_address_maps[LAST_PKMAP]; | |
408 | ||
409 | void __init page_address_init(void) | |
410 | { | |
411 | int i; | |
412 | ||
413 | INIT_LIST_HEAD(&page_address_pool); | |
414 | for (i = 0; i < ARRAY_SIZE(page_address_maps); i++) | |
415 | list_add(&page_address_maps[i].list, &page_address_pool); | |
416 | for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) { | |
417 | INIT_LIST_HEAD(&page_address_htable[i].lh); | |
418 | spin_lock_init(&page_address_htable[i].lock); | |
419 | } | |
420 | spin_lock_init(&pool_lock); | |
421 | } | |
422 | ||
423 | #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */ | |
424 | ||
425 | #if defined(CONFIG_DEBUG_HIGHMEM) && defined(CONFIG_TRACE_IRQFLAGS_SUPPORT) | |
426 | ||
427 | void debug_kmap_atomic(enum km_type type) | |
428 | { | |
429 | static int warn_count = 10; | |
430 | ||
431 | if (unlikely(warn_count < 0)) | |
432 | return; | |
433 | ||
434 | if (unlikely(in_interrupt())) { | |
435 | if (in_nmi()) { | |
436 | if (type != KM_NMI && type != KM_NMI_PTE) { | |
437 | WARN_ON(1); | |
438 | warn_count--; | |
439 | } | |
440 | } else if (in_irq()) { | |
441 | if (type != KM_IRQ0 && type != KM_IRQ1 && | |
442 | type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ && | |
443 | type != KM_BOUNCE_READ && type != KM_IRQ_PTE) { | |
444 | WARN_ON(1); | |
445 | warn_count--; | |
446 | } | |
447 | } else if (!irqs_disabled()) { /* softirq */ | |
448 | if (type != KM_IRQ0 && type != KM_IRQ1 && | |
449 | type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 && | |
450 | type != KM_SKB_SUNRPC_DATA && | |
451 | type != KM_SKB_DATA_SOFTIRQ && | |
452 | type != KM_BOUNCE_READ) { | |
453 | WARN_ON(1); | |
454 | warn_count--; | |
455 | } | |
456 | } | |
457 | } | |
458 | ||
459 | if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ || | |
460 | type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ || | |
461 | type == KM_IRQ_PTE || type == KM_NMI || | |
462 | type == KM_NMI_PTE ) { | |
463 | if (!irqs_disabled()) { | |
464 | WARN_ON(1); | |
465 | warn_count--; | |
466 | } | |
467 | } else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) { | |
468 | if (irq_count() == 0 && !irqs_disabled()) { | |
469 | WARN_ON(1); | |
470 | warn_count--; | |
471 | } | |
472 | } | |
473 | } | |
474 | ||
475 | #endif |