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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 <linux/kgdb.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. If and only if 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 | #ifdef CONFIG_DEBUG_HIGHMEM |
427 | |
428 | void debug_kmap_atomic(enum km_type type) |
429 | { |
430 | static int warn_count = 10; |
431 | |
432 | if (unlikely(warn_count < 0)) |
433 | return; |
434 | |
435 | if (unlikely(in_interrupt())) { |
436 | 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()) { |
442 | if (type != KM_IRQ0 && type != KM_IRQ1 && |
443 | type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ && |
444 | type != KM_BOUNCE_READ && type != KM_IRQ_PTE) { |
445 | 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 || |
461 | type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ || |
462 | type == KM_IRQ_PTE || type == KM_NMI || |
463 | type == KM_NMI_PTE ) { |
464 | 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 | } |
474 | #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 */ |
480 | } |
481 | |
482 | #endif |
483 |
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