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Commit | Line | Data |
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1da177e4 LT |
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> | |
eac79005 | 29 | #include <linux/kgdb.h> |
1da177e4 LT |
30 | #include <asm/tlbflush.h> |
31 | ||
1da177e4 LT |
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 | |
260b2367 | 41 | |
c1f60a5a | 42 | unsigned long totalhigh_pages __read_mostly; |
db7a94d6 | 43 | EXPORT_SYMBOL(totalhigh_pages); |
c1f60a5a | 44 | |
3e4d3af5 PZ |
45 | |
46 | DEFINE_PER_CPU(int, __kmap_atomic_idx); | |
47 | EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx); | |
48 | ||
c1f60a5a CL |
49 | unsigned int nr_free_highpages (void) |
50 | { | |
51 | pg_data_t *pgdat; | |
52 | unsigned int pages = 0; | |
53 | ||
2a1e274a | 54 | for_each_online_pgdat(pgdat) { |
d23ad423 CL |
55 | pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM], |
56 | NR_FREE_PAGES); | |
2a1e274a MG |
57 | if (zone_movable_is_highmem()) |
58 | pages += zone_page_state( | |
59 | &pgdat->node_zones[ZONE_MOVABLE], | |
60 | NR_FREE_PAGES); | |
61 | } | |
c1f60a5a CL |
62 | |
63 | return pages; | |
64 | } | |
65 | ||
1da177e4 LT |
66 | static int pkmap_count[LAST_PKMAP]; |
67 | static unsigned int last_pkmap_nr; | |
68 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); | |
69 | ||
70 | pte_t * pkmap_page_table; | |
71 | ||
72 | static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); | |
73 | ||
3297e760 NP |
74 | /* |
75 | * Most architectures have no use for kmap_high_get(), so let's abstract | |
76 | * the disabling of IRQ out of the locking in that case to save on a | |
77 | * potential useless overhead. | |
78 | */ | |
79 | #ifdef ARCH_NEEDS_KMAP_HIGH_GET | |
80 | #define lock_kmap() spin_lock_irq(&kmap_lock) | |
81 | #define unlock_kmap() spin_unlock_irq(&kmap_lock) | |
82 | #define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags) | |
83 | #define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags) | |
84 | #else | |
85 | #define lock_kmap() spin_lock(&kmap_lock) | |
86 | #define unlock_kmap() spin_unlock(&kmap_lock) | |
87 | #define lock_kmap_any(flags) \ | |
88 | do { spin_lock(&kmap_lock); (void)(flags); } while (0) | |
89 | #define unlock_kmap_any(flags) \ | |
90 | do { spin_unlock(&kmap_lock); (void)(flags); } while (0) | |
91 | #endif | |
92 | ||
1da177e4 LT |
93 | static void flush_all_zero_pkmaps(void) |
94 | { | |
95 | int i; | |
5843d9a4 | 96 | int need_flush = 0; |
1da177e4 LT |
97 | |
98 | flush_cache_kmaps(); | |
99 | ||
100 | for (i = 0; i < LAST_PKMAP; i++) { | |
101 | struct page *page; | |
102 | ||
103 | /* | |
104 | * zero means we don't have anything to do, | |
105 | * >1 means that it is still in use. Only | |
106 | * a count of 1 means that it is free but | |
107 | * needs to be unmapped | |
108 | */ | |
109 | if (pkmap_count[i] != 1) | |
110 | continue; | |
111 | pkmap_count[i] = 0; | |
112 | ||
113 | /* sanity check */ | |
75babcac | 114 | BUG_ON(pte_none(pkmap_page_table[i])); |
1da177e4 LT |
115 | |
116 | /* | |
117 | * Don't need an atomic fetch-and-clear op here; | |
118 | * no-one has the page mapped, and cannot get at | |
119 | * its virtual address (and hence PTE) without first | |
120 | * getting the kmap_lock (which is held here). | |
121 | * So no dangers, even with speculative execution. | |
122 | */ | |
123 | page = pte_page(pkmap_page_table[i]); | |
124 | pte_clear(&init_mm, (unsigned long)page_address(page), | |
125 | &pkmap_page_table[i]); | |
126 | ||
127 | set_page_address(page, NULL); | |
5843d9a4 | 128 | need_flush = 1; |
1da177e4 | 129 | } |
5843d9a4 NP |
130 | if (need_flush) |
131 | flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP)); | |
1da177e4 LT |
132 | } |
133 | ||
77f6078a RD |
134 | /** |
135 | * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings | |
136 | */ | |
ce6234b5 JF |
137 | void kmap_flush_unused(void) |
138 | { | |
3297e760 | 139 | lock_kmap(); |
ce6234b5 | 140 | flush_all_zero_pkmaps(); |
3297e760 | 141 | unlock_kmap(); |
ce6234b5 JF |
142 | } |
143 | ||
1da177e4 LT |
144 | static inline unsigned long map_new_virtual(struct page *page) |
145 | { | |
146 | unsigned long vaddr; | |
147 | int count; | |
148 | ||
149 | start: | |
150 | count = LAST_PKMAP; | |
151 | /* Find an empty entry */ | |
152 | for (;;) { | |
153 | last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK; | |
154 | if (!last_pkmap_nr) { | |
155 | flush_all_zero_pkmaps(); | |
156 | count = LAST_PKMAP; | |
157 | } | |
158 | if (!pkmap_count[last_pkmap_nr]) | |
159 | break; /* Found a usable entry */ | |
160 | if (--count) | |
161 | continue; | |
162 | ||
163 | /* | |
164 | * Sleep for somebody else to unmap their entries | |
165 | */ | |
166 | { | |
167 | DECLARE_WAITQUEUE(wait, current); | |
168 | ||
169 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
170 | add_wait_queue(&pkmap_map_wait, &wait); | |
3297e760 | 171 | unlock_kmap(); |
1da177e4 LT |
172 | schedule(); |
173 | remove_wait_queue(&pkmap_map_wait, &wait); | |
3297e760 | 174 | lock_kmap(); |
1da177e4 LT |
175 | |
176 | /* Somebody else might have mapped it while we slept */ | |
177 | if (page_address(page)) | |
178 | return (unsigned long)page_address(page); | |
179 | ||
180 | /* Re-start */ | |
181 | goto start; | |
182 | } | |
183 | } | |
184 | vaddr = PKMAP_ADDR(last_pkmap_nr); | |
185 | set_pte_at(&init_mm, vaddr, | |
186 | &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot)); | |
187 | ||
188 | pkmap_count[last_pkmap_nr] = 1; | |
189 | set_page_address(page, (void *)vaddr); | |
190 | ||
191 | return vaddr; | |
192 | } | |
193 | ||
77f6078a RD |
194 | /** |
195 | * kmap_high - map a highmem page into memory | |
196 | * @page: &struct page to map | |
197 | * | |
198 | * Returns the page's virtual memory address. | |
199 | * | |
200 | * We cannot call this from interrupts, as it may block. | |
201 | */ | |
920c7a5d | 202 | void *kmap_high(struct page *page) |
1da177e4 LT |
203 | { |
204 | unsigned long vaddr; | |
205 | ||
206 | /* | |
207 | * For highmem pages, we can't trust "virtual" until | |
208 | * after we have the lock. | |
1da177e4 | 209 | */ |
3297e760 | 210 | lock_kmap(); |
1da177e4 LT |
211 | vaddr = (unsigned long)page_address(page); |
212 | if (!vaddr) | |
213 | vaddr = map_new_virtual(page); | |
214 | pkmap_count[PKMAP_NR(vaddr)]++; | |
75babcac | 215 | BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2); |
3297e760 | 216 | unlock_kmap(); |
1da177e4 LT |
217 | return (void*) vaddr; |
218 | } | |
219 | ||
220 | EXPORT_SYMBOL(kmap_high); | |
221 | ||
3297e760 NP |
222 | #ifdef ARCH_NEEDS_KMAP_HIGH_GET |
223 | /** | |
224 | * kmap_high_get - pin a highmem page into memory | |
225 | * @page: &struct page to pin | |
226 | * | |
227 | * Returns the page's current virtual memory address, or NULL if no mapping | |
5e39df56 | 228 | * exists. If and only if a non null address is returned then a |
3297e760 NP |
229 | * matching call to kunmap_high() is necessary. |
230 | * | |
231 | * This can be called from any context. | |
232 | */ | |
233 | void *kmap_high_get(struct page *page) | |
234 | { | |
235 | unsigned long vaddr, flags; | |
236 | ||
237 | lock_kmap_any(flags); | |
238 | vaddr = (unsigned long)page_address(page); | |
239 | if (vaddr) { | |
240 | BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1); | |
241 | pkmap_count[PKMAP_NR(vaddr)]++; | |
242 | } | |
243 | unlock_kmap_any(flags); | |
244 | return (void*) vaddr; | |
245 | } | |
246 | #endif | |
247 | ||
77f6078a RD |
248 | /** |
249 | * kunmap_high - map a highmem page into memory | |
250 | * @page: &struct page to unmap | |
3297e760 NP |
251 | * |
252 | * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called | |
253 | * only from user context. | |
77f6078a | 254 | */ |
920c7a5d | 255 | void kunmap_high(struct page *page) |
1da177e4 LT |
256 | { |
257 | unsigned long vaddr; | |
258 | unsigned long nr; | |
3297e760 | 259 | unsigned long flags; |
1da177e4 LT |
260 | int need_wakeup; |
261 | ||
3297e760 | 262 | lock_kmap_any(flags); |
1da177e4 | 263 | vaddr = (unsigned long)page_address(page); |
75babcac | 264 | BUG_ON(!vaddr); |
1da177e4 LT |
265 | nr = PKMAP_NR(vaddr); |
266 | ||
267 | /* | |
268 | * A count must never go down to zero | |
269 | * without a TLB flush! | |
270 | */ | |
271 | need_wakeup = 0; | |
272 | switch (--pkmap_count[nr]) { | |
273 | case 0: | |
274 | BUG(); | |
275 | case 1: | |
276 | /* | |
277 | * Avoid an unnecessary wake_up() function call. | |
278 | * The common case is pkmap_count[] == 1, but | |
279 | * no waiters. | |
280 | * The tasks queued in the wait-queue are guarded | |
281 | * by both the lock in the wait-queue-head and by | |
282 | * the kmap_lock. As the kmap_lock is held here, | |
283 | * no need for the wait-queue-head's lock. Simply | |
284 | * test if the queue is empty. | |
285 | */ | |
286 | need_wakeup = waitqueue_active(&pkmap_map_wait); | |
287 | } | |
3297e760 | 288 | unlock_kmap_any(flags); |
1da177e4 LT |
289 | |
290 | /* do wake-up, if needed, race-free outside of the spin lock */ | |
291 | if (need_wakeup) | |
292 | wake_up(&pkmap_map_wait); | |
293 | } | |
294 | ||
295 | EXPORT_SYMBOL(kunmap_high); | |
1da177e4 LT |
296 | #endif |
297 | ||
1da177e4 LT |
298 | #if defined(HASHED_PAGE_VIRTUAL) |
299 | ||
300 | #define PA_HASH_ORDER 7 | |
301 | ||
302 | /* | |
303 | * Describes one page->virtual association | |
304 | */ | |
305 | struct page_address_map { | |
306 | struct page *page; | |
307 | void *virtual; | |
308 | struct list_head list; | |
309 | }; | |
310 | ||
311 | /* | |
312 | * page_address_map freelist, allocated from page_address_maps. | |
313 | */ | |
314 | static struct list_head page_address_pool; /* freelist */ | |
315 | static spinlock_t pool_lock; /* protects page_address_pool */ | |
316 | ||
317 | /* | |
318 | * Hash table bucket | |
319 | */ | |
320 | static struct page_address_slot { | |
321 | struct list_head lh; /* List of page_address_maps */ | |
322 | spinlock_t lock; /* Protect this bucket's list */ | |
323 | } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER]; | |
324 | ||
325 | static struct page_address_slot *page_slot(struct page *page) | |
326 | { | |
327 | return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)]; | |
328 | } | |
329 | ||
77f6078a RD |
330 | /** |
331 | * page_address - get the mapped virtual address of a page | |
332 | * @page: &struct page to get the virtual address of | |
333 | * | |
334 | * Returns the page's virtual address. | |
335 | */ | |
1da177e4 LT |
336 | void *page_address(struct page *page) |
337 | { | |
338 | unsigned long flags; | |
339 | void *ret; | |
340 | struct page_address_slot *pas; | |
341 | ||
342 | if (!PageHighMem(page)) | |
343 | return lowmem_page_address(page); | |
344 | ||
345 | pas = page_slot(page); | |
346 | ret = NULL; | |
347 | spin_lock_irqsave(&pas->lock, flags); | |
348 | if (!list_empty(&pas->lh)) { | |
349 | struct page_address_map *pam; | |
350 | ||
351 | list_for_each_entry(pam, &pas->lh, list) { | |
352 | if (pam->page == page) { | |
353 | ret = pam->virtual; | |
354 | goto done; | |
355 | } | |
356 | } | |
357 | } | |
358 | done: | |
359 | spin_unlock_irqrestore(&pas->lock, flags); | |
360 | return ret; | |
361 | } | |
362 | ||
363 | EXPORT_SYMBOL(page_address); | |
364 | ||
77f6078a RD |
365 | /** |
366 | * set_page_address - set a page's virtual address | |
367 | * @page: &struct page to set | |
368 | * @virtual: virtual address to use | |
369 | */ | |
1da177e4 LT |
370 | void set_page_address(struct page *page, void *virtual) |
371 | { | |
372 | unsigned long flags; | |
373 | struct page_address_slot *pas; | |
374 | struct page_address_map *pam; | |
375 | ||
376 | BUG_ON(!PageHighMem(page)); | |
377 | ||
378 | pas = page_slot(page); | |
379 | if (virtual) { /* Add */ | |
380 | BUG_ON(list_empty(&page_address_pool)); | |
381 | ||
382 | spin_lock_irqsave(&pool_lock, flags); | |
383 | pam = list_entry(page_address_pool.next, | |
384 | struct page_address_map, list); | |
385 | list_del(&pam->list); | |
386 | spin_unlock_irqrestore(&pool_lock, flags); | |
387 | ||
388 | pam->page = page; | |
389 | pam->virtual = virtual; | |
390 | ||
391 | spin_lock_irqsave(&pas->lock, flags); | |
392 | list_add_tail(&pam->list, &pas->lh); | |
393 | spin_unlock_irqrestore(&pas->lock, flags); | |
394 | } else { /* Remove */ | |
395 | spin_lock_irqsave(&pas->lock, flags); | |
396 | list_for_each_entry(pam, &pas->lh, list) { | |
397 | if (pam->page == page) { | |
398 | list_del(&pam->list); | |
399 | spin_unlock_irqrestore(&pas->lock, flags); | |
400 | spin_lock_irqsave(&pool_lock, flags); | |
401 | list_add_tail(&pam->list, &page_address_pool); | |
402 | spin_unlock_irqrestore(&pool_lock, flags); | |
403 | goto done; | |
404 | } | |
405 | } | |
406 | spin_unlock_irqrestore(&pas->lock, flags); | |
407 | } | |
408 | done: | |
409 | return; | |
410 | } | |
411 | ||
412 | static struct page_address_map page_address_maps[LAST_PKMAP]; | |
413 | ||
414 | void __init page_address_init(void) | |
415 | { | |
416 | int i; | |
417 | ||
418 | INIT_LIST_HEAD(&page_address_pool); | |
419 | for (i = 0; i < ARRAY_SIZE(page_address_maps); i++) | |
420 | list_add(&page_address_maps[i].list, &page_address_pool); | |
421 | for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) { | |
422 | INIT_LIST_HEAD(&page_address_htable[i].lh); | |
423 | spin_lock_init(&page_address_htable[i].lock); | |
424 | } | |
425 | spin_lock_init(&pool_lock); | |
426 | } | |
427 | ||
428 | #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */ |