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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. If and only if 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 |
476 |
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