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Source at commit b05a5adf03613de371c77c3235f7d970d7cd0c71 created 13 years 1 month ago. By Lars-Peter Clausen, NAND: Optimize reading the eec data for the JZ4740 (evil hack) | |
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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 | #if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32) |
34 | DEFINE_PER_CPU(int, __kmap_atomic_idx); |
35 | #endif |
36 | |
37 | /* |
38 | * Virtual_count is not a pure "count". |
39 | * 0 means that it is not mapped, and has not been mapped |
40 | * since a TLB flush - it is usable. |
41 | * 1 means that there are no users, but it has been mapped |
42 | * since the last TLB flush - so we can't use it. |
43 | * n means that there are (n-1) current users of it. |
44 | */ |
45 | #ifdef CONFIG_HIGHMEM |
46 | |
47 | unsigned long totalhigh_pages __read_mostly; |
48 | EXPORT_SYMBOL(totalhigh_pages); |
49 | |
50 | |
51 | EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx); |
52 | |
53 | unsigned int nr_free_highpages (void) |
54 | { |
55 | pg_data_t *pgdat; |
56 | unsigned int pages = 0; |
57 | |
58 | for_each_online_pgdat(pgdat) { |
59 | pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM], |
60 | NR_FREE_PAGES); |
61 | if (zone_movable_is_highmem()) |
62 | pages += zone_page_state( |
63 | &pgdat->node_zones[ZONE_MOVABLE], |
64 | NR_FREE_PAGES); |
65 | } |
66 | |
67 | return pages; |
68 | } |
69 | |
70 | static int pkmap_count[LAST_PKMAP]; |
71 | static unsigned int last_pkmap_nr; |
72 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); |
73 | |
74 | pte_t * pkmap_page_table; |
75 | |
76 | static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); |
77 | |
78 | /* |
79 | * Most architectures have no use for kmap_high_get(), so let's abstract |
80 | * the disabling of IRQ out of the locking in that case to save on a |
81 | * potential useless overhead. |
82 | */ |
83 | #ifdef ARCH_NEEDS_KMAP_HIGH_GET |
84 | #define lock_kmap() spin_lock_irq(&kmap_lock) |
85 | #define unlock_kmap() spin_unlock_irq(&kmap_lock) |
86 | #define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags) |
87 | #define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags) |
88 | #else |
89 | #define lock_kmap() spin_lock(&kmap_lock) |
90 | #define unlock_kmap() spin_unlock(&kmap_lock) |
91 | #define lock_kmap_any(flags) \ |
92 | do { spin_lock(&kmap_lock); (void)(flags); } while (0) |
93 | #define unlock_kmap_any(flags) \ |
94 | do { spin_unlock(&kmap_lock); (void)(flags); } while (0) |
95 | #endif |
96 | |
97 | static void flush_all_zero_pkmaps(void) |
98 | { |
99 | int i; |
100 | int need_flush = 0; |
101 | |
102 | flush_cache_kmaps(); |
103 | |
104 | for (i = 0; i < LAST_PKMAP; i++) { |
105 | struct page *page; |
106 | |
107 | /* |
108 | * zero means we don't have anything to do, |
109 | * >1 means that it is still in use. Only |
110 | * a count of 1 means that it is free but |
111 | * needs to be unmapped |
112 | */ |
113 | if (pkmap_count[i] != 1) |
114 | continue; |
115 | pkmap_count[i] = 0; |
116 | |
117 | /* sanity check */ |
118 | BUG_ON(pte_none(pkmap_page_table[i])); |
119 | |
120 | /* |
121 | * Don't need an atomic fetch-and-clear op here; |
122 | * no-one has the page mapped, and cannot get at |
123 | * its virtual address (and hence PTE) without first |
124 | * getting the kmap_lock (which is held here). |
125 | * So no dangers, even with speculative execution. |
126 | */ |
127 | page = pte_page(pkmap_page_table[i]); |
128 | pte_clear(&init_mm, (unsigned long)page_address(page), |
129 | &pkmap_page_table[i]); |
130 | |
131 | set_page_address(page, NULL); |
132 | need_flush = 1; |
133 | } |
134 | if (need_flush) |
135 | flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP)); |
136 | } |
137 | |
138 | /** |
139 | * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings |
140 | */ |
141 | void kmap_flush_unused(void) |
142 | { |
143 | lock_kmap(); |
144 | flush_all_zero_pkmaps(); |
145 | unlock_kmap(); |
146 | } |
147 | |
148 | static inline unsigned long map_new_virtual(struct page *page) |
149 | { |
150 | unsigned long vaddr; |
151 | int count; |
152 | |
153 | start: |
154 | count = LAST_PKMAP; |
155 | /* Find an empty entry */ |
156 | for (;;) { |
157 | last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK; |
158 | if (!last_pkmap_nr) { |
159 | flush_all_zero_pkmaps(); |
160 | count = LAST_PKMAP; |
161 | } |
162 | if (!pkmap_count[last_pkmap_nr]) |
163 | break; /* Found a usable entry */ |
164 | if (--count) |
165 | continue; |
166 | |
167 | /* |
168 | * Sleep for somebody else to unmap their entries |
169 | */ |
170 | { |
171 | DECLARE_WAITQUEUE(wait, current); |
172 | |
173 | __set_current_state(TASK_UNINTERRUPTIBLE); |
174 | add_wait_queue(&pkmap_map_wait, &wait); |
175 | unlock_kmap(); |
176 | schedule(); |
177 | remove_wait_queue(&pkmap_map_wait, &wait); |
178 | lock_kmap(); |
179 | |
180 | /* Somebody else might have mapped it while we slept */ |
181 | if (page_address(page)) |
182 | return (unsigned long)page_address(page); |
183 | |
184 | /* Re-start */ |
185 | goto start; |
186 | } |
187 | } |
188 | vaddr = PKMAP_ADDR(last_pkmap_nr); |
189 | set_pte_at(&init_mm, vaddr, |
190 | &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot)); |
191 | |
192 | pkmap_count[last_pkmap_nr] = 1; |
193 | set_page_address(page, (void *)vaddr); |
194 | |
195 | return vaddr; |
196 | } |
197 | |
198 | /** |
199 | * kmap_high - map a highmem page into memory |
200 | * @page: &struct page to map |
201 | * |
202 | * Returns the page's virtual memory address. |
203 | * |
204 | * We cannot call this from interrupts, as it may block. |
205 | */ |
206 | void *kmap_high(struct page *page) |
207 | { |
208 | unsigned long vaddr; |
209 | |
210 | /* |
211 | * For highmem pages, we can't trust "virtual" until |
212 | * after we have the lock. |
213 | */ |
214 | lock_kmap(); |
215 | vaddr = (unsigned long)page_address(page); |
216 | if (!vaddr) |
217 | vaddr = map_new_virtual(page); |
218 | pkmap_count[PKMAP_NR(vaddr)]++; |
219 | BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2); |
220 | unlock_kmap(); |
221 | return (void*) vaddr; |
222 | } |
223 | |
224 | EXPORT_SYMBOL(kmap_high); |
225 | |
226 | #ifdef ARCH_NEEDS_KMAP_HIGH_GET |
227 | /** |
228 | * kmap_high_get - pin a highmem page into memory |
229 | * @page: &struct page to pin |
230 | * |
231 | * Returns the page's current virtual memory address, or NULL if no mapping |
232 | * exists. If and only if a non null address is returned then a |
233 | * matching call to kunmap_high() is necessary. |
234 | * |
235 | * This can be called from any context. |
236 | */ |
237 | void *kmap_high_get(struct page *page) |
238 | { |
239 | unsigned long vaddr, flags; |
240 | |
241 | lock_kmap_any(flags); |
242 | vaddr = (unsigned long)page_address(page); |
243 | if (vaddr) { |
244 | BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1); |
245 | pkmap_count[PKMAP_NR(vaddr)]++; |
246 | } |
247 | unlock_kmap_any(flags); |
248 | return (void*) vaddr; |
249 | } |
250 | #endif |
251 | |
252 | /** |
253 | * kunmap_high - map a highmem page into memory |
254 | * @page: &struct page to unmap |
255 | * |
256 | * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called |
257 | * only from user context. |
258 | */ |
259 | void kunmap_high(struct page *page) |
260 | { |
261 | unsigned long vaddr; |
262 | unsigned long nr; |
263 | unsigned long flags; |
264 | int need_wakeup; |
265 | |
266 | lock_kmap_any(flags); |
267 | vaddr = (unsigned long)page_address(page); |
268 | BUG_ON(!vaddr); |
269 | nr = PKMAP_NR(vaddr); |
270 | |
271 | /* |
272 | * A count must never go down to zero |
273 | * without a TLB flush! |
274 | */ |
275 | need_wakeup = 0; |
276 | switch (--pkmap_count[nr]) { |
277 | case 0: |
278 | BUG(); |
279 | case 1: |
280 | /* |
281 | * Avoid an unnecessary wake_up() function call. |
282 | * The common case is pkmap_count[] == 1, but |
283 | * no waiters. |
284 | * The tasks queued in the wait-queue are guarded |
285 | * by both the lock in the wait-queue-head and by |
286 | * the kmap_lock. As the kmap_lock is held here, |
287 | * no need for the wait-queue-head's lock. Simply |
288 | * test if the queue is empty. |
289 | */ |
290 | need_wakeup = waitqueue_active(&pkmap_map_wait); |
291 | } |
292 | unlock_kmap_any(flags); |
293 | |
294 | /* do wake-up, if needed, race-free outside of the spin lock */ |
295 | if (need_wakeup) |
296 | wake_up(&pkmap_map_wait); |
297 | } |
298 | |
299 | EXPORT_SYMBOL(kunmap_high); |
300 | #endif |
301 | |
302 | #if defined(HASHED_PAGE_VIRTUAL) |
303 | |
304 | #define PA_HASH_ORDER 7 |
305 | |
306 | /* |
307 | * Describes one page->virtual association |
308 | */ |
309 | struct page_address_map { |
310 | struct page *page; |
311 | void *virtual; |
312 | struct list_head list; |
313 | }; |
314 | |
315 | /* |
316 | * page_address_map freelist, allocated from page_address_maps. |
317 | */ |
318 | static struct list_head page_address_pool; /* freelist */ |
319 | static spinlock_t pool_lock; /* protects page_address_pool */ |
320 | |
321 | /* |
322 | * Hash table bucket |
323 | */ |
324 | static struct page_address_slot { |
325 | struct list_head lh; /* List of page_address_maps */ |
326 | spinlock_t lock; /* Protect this bucket's list */ |
327 | } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER]; |
328 | |
329 | static struct page_address_slot *page_slot(struct page *page) |
330 | { |
331 | return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)]; |
332 | } |
333 | |
334 | /** |
335 | * page_address - get the mapped virtual address of a page |
336 | * @page: &struct page to get the virtual address of |
337 | * |
338 | * Returns the page's virtual address. |
339 | */ |
340 | void *page_address(struct page *page) |
341 | { |
342 | unsigned long flags; |
343 | void *ret; |
344 | struct page_address_slot *pas; |
345 | |
346 | if (!PageHighMem(page)) |
347 | return lowmem_page_address(page); |
348 | |
349 | pas = page_slot(page); |
350 | ret = NULL; |
351 | spin_lock_irqsave(&pas->lock, flags); |
352 | if (!list_empty(&pas->lh)) { |
353 | struct page_address_map *pam; |
354 | |
355 | list_for_each_entry(pam, &pas->lh, list) { |
356 | if (pam->page == page) { |
357 | ret = pam->virtual; |
358 | goto done; |
359 | } |
360 | } |
361 | } |
362 | done: |
363 | spin_unlock_irqrestore(&pas->lock, flags); |
364 | return ret; |
365 | } |
366 | |
367 | EXPORT_SYMBOL(page_address); |
368 | |
369 | /** |
370 | * set_page_address - set a page's virtual address |
371 | * @page: &struct page to set |
372 | * @virtual: virtual address to use |
373 | */ |
374 | void set_page_address(struct page *page, void *virtual) |
375 | { |
376 | unsigned long flags; |
377 | struct page_address_slot *pas; |
378 | struct page_address_map *pam; |
379 | |
380 | BUG_ON(!PageHighMem(page)); |
381 | |
382 | pas = page_slot(page); |
383 | if (virtual) { /* Add */ |
384 | BUG_ON(list_empty(&page_address_pool)); |
385 | |
386 | spin_lock_irqsave(&pool_lock, flags); |
387 | pam = list_entry(page_address_pool.next, |
388 | struct page_address_map, list); |
389 | list_del(&pam->list); |
390 | spin_unlock_irqrestore(&pool_lock, flags); |
391 | |
392 | pam->page = page; |
393 | pam->virtual = virtual; |
394 | |
395 | spin_lock_irqsave(&pas->lock, flags); |
396 | list_add_tail(&pam->list, &pas->lh); |
397 | spin_unlock_irqrestore(&pas->lock, flags); |
398 | } else { /* Remove */ |
399 | spin_lock_irqsave(&pas->lock, flags); |
400 | list_for_each_entry(pam, &pas->lh, list) { |
401 | if (pam->page == page) { |
402 | list_del(&pam->list); |
403 | spin_unlock_irqrestore(&pas->lock, flags); |
404 | spin_lock_irqsave(&pool_lock, flags); |
405 | list_add_tail(&pam->list, &page_address_pool); |
406 | spin_unlock_irqrestore(&pool_lock, flags); |
407 | goto done; |
408 | } |
409 | } |
410 | spin_unlock_irqrestore(&pas->lock, flags); |
411 | } |
412 | done: |
413 | return; |
414 | } |
415 | |
416 | static struct page_address_map page_address_maps[LAST_PKMAP]; |
417 | |
418 | void __init page_address_init(void) |
419 | { |
420 | int i; |
421 | |
422 | INIT_LIST_HEAD(&page_address_pool); |
423 | for (i = 0; i < ARRAY_SIZE(page_address_maps); i++) |
424 | list_add(&page_address_maps[i].list, &page_address_pool); |
425 | for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) { |
426 | INIT_LIST_HEAD(&page_address_htable[i].lh); |
427 | spin_lock_init(&page_address_htable[i].lock); |
428 | } |
429 | spin_lock_init(&pool_lock); |
430 | } |
431 | |
432 | #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */ |
433 |
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