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 static mempool_t *page_pool, *isa_page_pool;
32
33 static void *page_pool_alloc(int gfp_mask, void *data)
34 {
35 int gfp = gfp_mask | (int) (long) data;
36
37 return alloc_page(gfp);
38 }
39
40 static void page_pool_free(void *page, void *data)
41 {
42 __free_page(page);
43 }
44
45 /*
46 * Virtual_count is not a pure "count".
47 * 0 means that it is not mapped, and has not been mapped
48 * since a TLB flush - it is usable.
49 * 1 means that there are no users, but it has been mapped
50 * since the last TLB flush - so we can't use it.
51 * n means that there are (n-1) current users of it.
52 */
53 #ifdef CONFIG_HIGHMEM
54 static int pkmap_count[LAST_PKMAP];
55 static unsigned int last_pkmap_nr;
56 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
57
58 pte_t * pkmap_page_table;
59
60 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
61
62 static void flush_all_zero_pkmaps(void)
63 {
64 int i;
65
66 flush_cache_kmaps();
67
68 for (i = 0; i < LAST_PKMAP; i++) {
69 struct page *page;
70
71 /*
72 * zero means we don't have anything to do,
73 * >1 means that it is still in use. Only
74 * a count of 1 means that it is free but
75 * needs to be unmapped
76 */
77 if (pkmap_count[i] != 1)
78 continue;
79 pkmap_count[i] = 0;
80
81 /* sanity check */
82 if (pte_none(pkmap_page_table[i]))
83 BUG();
84
85 /*
86 * Don't need an atomic fetch-and-clear op here;
87 * no-one has the page mapped, and cannot get at
88 * its virtual address (and hence PTE) without first
89 * getting the kmap_lock (which is held here).
90 * So no dangers, even with speculative execution.
91 */
92 page = pte_page(pkmap_page_table[i]);
93 pte_clear(&pkmap_page_table[i]);
94
95 set_page_address(page, NULL);
96 }
97 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
98 }
99
100 static inline unsigned long map_new_virtual(struct page *page)
101 {
102 unsigned long vaddr;
103 int count;
104
105 start:
106 count = LAST_PKMAP;
107 /* Find an empty entry */
108 for (;;) {
109 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
110 if (!last_pkmap_nr) {
111 flush_all_zero_pkmaps();
112 count = LAST_PKMAP;
113 }
114 if (!pkmap_count[last_pkmap_nr])
115 break; /* Found a usable entry */
116 if (--count)
117 continue;
118
119 /*
120 * Sleep for somebody else to unmap their entries
121 */
122 {
123 DECLARE_WAITQUEUE(wait, current);
124
125 __set_current_state(TASK_UNINTERRUPTIBLE);
126 add_wait_queue(&pkmap_map_wait, &wait);
127 spin_unlock(&kmap_lock);
128 schedule();
129 remove_wait_queue(&pkmap_map_wait, &wait);
130 spin_lock(&kmap_lock);
131
132 /* Somebody else might have mapped it while we slept */
133 if (page_address(page))
134 return (unsigned long)page_address(page);
135
136 /* Re-start */
137 goto start;
138 }
139 }
140 vaddr = PKMAP_ADDR(last_pkmap_nr);
141 set_pte(&(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
142
143 pkmap_count[last_pkmap_nr] = 1;
144 set_page_address(page, (void *)vaddr);
145
146 return vaddr;
147 }
148
149 void fastcall *kmap_high(struct page *page)
150 {
151 unsigned long vaddr;
152
153 /*
154 * For highmem pages, we can't trust "virtual" until
155 * after we have the lock.
156 *
157 * We cannot call this from interrupts, as it may block
158 */
159 spin_lock(&kmap_lock);
160 vaddr = (unsigned long)page_address(page);
161 if (!vaddr)
162 vaddr = map_new_virtual(page);
163 pkmap_count[PKMAP_NR(vaddr)]++;
164 if (pkmap_count[PKMAP_NR(vaddr)] < 2)
165 BUG();
166 spin_unlock(&kmap_lock);
167 return (void*) vaddr;
168 }
169
170 EXPORT_SYMBOL(kmap_high);
171
172 void fastcall kunmap_high(struct page *page)
173 {
174 unsigned long vaddr;
175 unsigned long nr;
176 int need_wakeup;
177
178 spin_lock(&kmap_lock);
179 vaddr = (unsigned long)page_address(page);
180 if (!vaddr)
181 BUG();
182 nr = PKMAP_NR(vaddr);
183
184 /*
185 * A count must never go down to zero
186 * without a TLB flush!
187 */
188 need_wakeup = 0;
189 switch (--pkmap_count[nr]) {
190 case 0:
191 BUG();
192 case 1:
193 /*
194 * Avoid an unnecessary wake_up() function call.
195 * The common case is pkmap_count[] == 1, but
196 * no waiters.
197 * The tasks queued in the wait-queue are guarded
198 * by both the lock in the wait-queue-head and by
199 * the kmap_lock. As the kmap_lock is held here,
200 * no need for the wait-queue-head's lock. Simply
201 * test if the queue is empty.
202 */
203 need_wakeup = waitqueue_active(&pkmap_map_wait);
204 }
205 spin_unlock(&kmap_lock);
206
207 /* do wake-up, if needed, race-free outside of the spin lock */
208 if (need_wakeup)
209 wake_up(&pkmap_map_wait);
210 }
211
212 EXPORT_SYMBOL(kunmap_high);
213
214 #define POOL_SIZE 64
215
216 static __init int init_emergency_pool(void)
217 {
218 struct sysinfo i;
219 si_meminfo(&i);
220 si_swapinfo(&i);
221
222 if (!i.totalhigh)
223 return 0;
224
225 page_pool = mempool_create(POOL_SIZE, page_pool_alloc, page_pool_free, NULL);
226 if (!page_pool)
227 BUG();
228 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
229
230 return 0;
231 }
232
233 __initcall(init_emergency_pool);
234
235 /*
236 * highmem version, map in to vec
237 */
238 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
239 {
240 unsigned long flags;
241 unsigned char *vto;
242
243 local_irq_save(flags);
244 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
245 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
246 kunmap_atomic(vto, KM_BOUNCE_READ);
247 local_irq_restore(flags);
248 }
249
250 #else /* CONFIG_HIGHMEM */
251
252 #define bounce_copy_vec(to, vfrom) \
253 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
254
255 #endif
256
257 #define ISA_POOL_SIZE 16
258
259 /*
260 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
261 * as the max address, so check if the pool has already been created.
262 */
263 int init_emergency_isa_pool(void)
264 {
265 if (isa_page_pool)
266 return 0;
267
268 isa_page_pool = mempool_create(ISA_POOL_SIZE, page_pool_alloc, page_pool_free, (void *) __GFP_DMA);
269 if (!isa_page_pool)
270 BUG();
271
272 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
273 return 0;
274 }
275
276 /*
277 * Simple bounce buffer support for highmem pages. Depending on the
278 * queue gfp mask set, *to may or may not be a highmem page. kmap it
279 * always, it will do the Right Thing
280 */
281 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
282 {
283 unsigned char *vfrom;
284 struct bio_vec *tovec, *fromvec;
285 int i;
286
287 __bio_for_each_segment(tovec, to, i, 0) {
288 fromvec = from->bi_io_vec + i;
289
290 /*
291 * not bounced
292 */
293 if (tovec->bv_page == fromvec->bv_page)
294 continue;
295
296 /*
297 * fromvec->bv_offset and fromvec->bv_len might have been
298 * modified by the block layer, so use the original copy,
299 * bounce_copy_vec already uses tovec->bv_len
300 */
301 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
302
303 flush_dcache_page(tovec->bv_page);
304 bounce_copy_vec(tovec, vfrom);
305 }
306 }
307
308 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
309 {
310 struct bio *bio_orig = bio->bi_private;
311 struct bio_vec *bvec, *org_vec;
312 int i;
313
314 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
315 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
316
317 /*
318 * free up bounce indirect pages used
319 */
320 __bio_for_each_segment(bvec, bio, i, 0) {
321 org_vec = bio_orig->bi_io_vec + i;
322 if (bvec->bv_page == org_vec->bv_page)
323 continue;
324
325 mempool_free(bvec->bv_page, pool);
326 }
327
328 bio_endio(bio_orig, bio_orig->bi_size, err);
329 bio_put(bio);
330 }
331
332 static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done,int err)
333 {
334 if (bio->bi_size)
335 return 1;
336
337 bounce_end_io(bio, page_pool, err);
338 return 0;
339 }
340
341 static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err)
342 {
343 if (bio->bi_size)
344 return 1;
345
346 bounce_end_io(bio, isa_page_pool, err);
347 return 0;
348 }
349
350 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
351 {
352 struct bio *bio_orig = bio->bi_private;
353
354 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
355 copy_to_high_bio_irq(bio_orig, bio);
356
357 bounce_end_io(bio, pool, err);
358 }
359
360 static int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
361 {
362 if (bio->bi_size)
363 return 1;
364
365 __bounce_end_io_read(bio, page_pool, err);
366 return 0;
367 }
368
369 static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err)
370 {
371 if (bio->bi_size)
372 return 1;
373
374 __bounce_end_io_read(bio, isa_page_pool, err);
375 return 0;
376 }
377
378 static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig,
379 mempool_t *pool)
380 {
381 struct page *page;
382 struct bio *bio = NULL;
383 int i, rw = bio_data_dir(*bio_orig);
384 struct bio_vec *to, *from;
385
386 bio_for_each_segment(from, *bio_orig, i) {
387 page = from->bv_page;
388
389 /*
390 * is destination page below bounce pfn?
391 */
392 if (page_to_pfn(page) < q->bounce_pfn)
393 continue;
394
395 /*
396 * irk, bounce it
397 */
398 if (!bio)
399 bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
400
401 to = bio->bi_io_vec + i;
402
403 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
404 to->bv_len = from->bv_len;
405 to->bv_offset = from->bv_offset;
406
407 if (rw == WRITE) {
408 char *vto, *vfrom;
409
410 flush_dcache_page(from->bv_page);
411 vto = page_address(to->bv_page) + to->bv_offset;
412 vfrom = kmap(from->bv_page) + from->bv_offset;
413 memcpy(vto, vfrom, to->bv_len);
414 kunmap(from->bv_page);
415 }
416 }
417
418 /*
419 * no pages bounced
420 */
421 if (!bio)
422 return;
423
424 /*
425 * at least one page was bounced, fill in possible non-highmem
426 * pages
427 */
428 __bio_for_each_segment(from, *bio_orig, i, 0) {
429 to = bio_iovec_idx(bio, i);
430 if (!to->bv_page) {
431 to->bv_page = from->bv_page;
432 to->bv_len = from->bv_len;
433 to->bv_offset = from->bv_offset;
434 }
435 }
436
437 bio->bi_bdev = (*bio_orig)->bi_bdev;
438 bio->bi_flags |= (1 << BIO_BOUNCED);
439 bio->bi_sector = (*bio_orig)->bi_sector;
440 bio->bi_rw = (*bio_orig)->bi_rw;
441
442 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
443 bio->bi_idx = (*bio_orig)->bi_idx;
444 bio->bi_size = (*bio_orig)->bi_size;
445
446 if (pool == page_pool) {
447 bio->bi_end_io = bounce_end_io_write;
448 if (rw == READ)
449 bio->bi_end_io = bounce_end_io_read;
450 } else {
451 bio->bi_end_io = bounce_end_io_write_isa;
452 if (rw == READ)
453 bio->bi_end_io = bounce_end_io_read_isa;
454 }
455
456 bio->bi_private = *bio_orig;
457 *bio_orig = bio;
458 }
459
460 void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig)
461 {
462 mempool_t *pool;
463
464 /*
465 * for non-isa bounce case, just check if the bounce pfn is equal
466 * to or bigger than the highest pfn in the system -- in that case,
467 * don't waste time iterating over bio segments
468 */
469 if (!(q->bounce_gfp & GFP_DMA)) {
470 if (q->bounce_pfn >= blk_max_pfn)
471 return;
472 pool = page_pool;
473 } else {
474 BUG_ON(!isa_page_pool);
475 pool = isa_page_pool;
476 }
477
478 /*
479 * slow path
480 */
481 __blk_queue_bounce(q, bio_orig, pool);
482 }
483
484 EXPORT_SYMBOL(blk_queue_bounce);
485
486 #if defined(HASHED_PAGE_VIRTUAL)
487
488 #define PA_HASH_ORDER 7
489
490 /*
491 * Describes one page->virtual association
492 */
493 struct page_address_map {
494 struct page *page;
495 void *virtual;
496 struct list_head list;
497 };
498
499 /*
500 * page_address_map freelist, allocated from page_address_maps.
501 */
502 static struct list_head page_address_pool; /* freelist */
503 static spinlock_t pool_lock; /* protects page_address_pool */
504
505 /*
506 * Hash table bucket
507 */
508 static struct page_address_slot {
509 struct list_head lh; /* List of page_address_maps */
510 spinlock_t lock; /* Protect this bucket's list */
511 } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
512
513 static struct page_address_slot *page_slot(struct page *page)
514 {
515 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
516 }
517
518 void *page_address(struct page *page)
519 {
520 unsigned long flags;
521 void *ret;
522 struct page_address_slot *pas;
523
524 if (!PageHighMem(page))
525 return lowmem_page_address(page);
526
527 pas = page_slot(page);
528 ret = NULL;
529 spin_lock_irqsave(&pas->lock, flags);
530 if (!list_empty(&pas->lh)) {
531 struct page_address_map *pam;
532
533 list_for_each_entry(pam, &pas->lh, list) {
534 if (pam->page == page) {
535 ret = pam->virtual;
536 goto done;
537 }
538 }
539 }
540 done:
541 spin_unlock_irqrestore(&pas->lock, flags);
542 return ret;
543 }
544
545 EXPORT_SYMBOL(page_address);
546
547 void set_page_address(struct page *page, void *virtual)
548 {
549 unsigned long flags;
550 struct page_address_slot *pas;
551 struct page_address_map *pam;
552
553 BUG_ON(!PageHighMem(page));
554
555 pas = page_slot(page);
556 if (virtual) { /* Add */
557 BUG_ON(list_empty(&page_address_pool));
558
559 spin_lock_irqsave(&pool_lock, flags);
560 pam = list_entry(page_address_pool.next,
561 struct page_address_map, list);
562 list_del(&pam->list);
563 spin_unlock_irqrestore(&pool_lock, flags);
564
565 pam->page = page;
566 pam->virtual = virtual;
567
568 spin_lock_irqsave(&pas->lock, flags);
569 list_add_tail(&pam->list, &pas->lh);
570 spin_unlock_irqrestore(&pas->lock, flags);
571 } else { /* Remove */
572 spin_lock_irqsave(&pas->lock, flags);
573 list_for_each_entry(pam, &pas->lh, list) {
574 if (pam->page == page) {
575 list_del(&pam->list);
576 spin_unlock_irqrestore(&pas->lock, flags);
577 spin_lock_irqsave(&pool_lock, flags);
578 list_add_tail(&pam->list, &page_address_pool);
579 spin_unlock_irqrestore(&pool_lock, flags);
580 goto done;
581 }
582 }
583 spin_unlock_irqrestore(&pas->lock, flags);
584 }
585 done:
586 return;
587 }
588
589 static struct page_address_map page_address_maps[LAST_PKMAP];
590
591 void __init page_address_init(void)
592 {
593 int i;
594
595 INIT_LIST_HEAD(&page_address_pool);
596 for (i = 0; i < ARRAY_SIZE(page_address_maps); i++)
597 list_add(&page_address_maps[i].list, &page_address_pool);
598 for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
599 INIT_LIST_HEAD(&page_address_htable[i].lh);
600 spin_lock_init(&page_address_htable[i].lock);
601 }
602 spin_lock_init(&pool_lock);
603 }
604
605 #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */
606
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