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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 static mempool_t *page_pool, *isa_page_pool;
32
33 static void *page_pool_alloc_isa(gfp_t gfp_mask, void *data)
34 {
35 return alloc_page(gfp_mask | GFP_DMA);
36 }
37
38 static void page_pool_free(void *page, void *data)
39 {
40 __free_page(page);
41 }
42
43 /*
44 * Virtual_count is not a pure "count".
45 * 0 means that it is not mapped, and has not been mapped
46 * since a TLB flush - it is usable.
47 * 1 means that there are no users, but it has been mapped
48 * since the last TLB flush - so we can't use it.
49 * n means that there are (n-1) current users of it.
50 */
51 #ifdef CONFIG_HIGHMEM
52
53 static void *page_pool_alloc(gfp_t gfp_mask, void *data)
54 {
55 return alloc_page(gfp_mask);
56 }
57
58 static int pkmap_count[LAST_PKMAP];
59 static unsigned int last_pkmap_nr;
60 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
61
62 pte_t * pkmap_page_table;
63
64 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
65
66 static void flush_all_zero_pkmaps(void)
67 {
68 int i;
69
70 flush_cache_kmaps();
71
72 for (i = 0; i < LAST_PKMAP; i++) {
73 struct page *page;
74
75 /*
76 * zero means we don't have anything to do,
77 * >1 means that it is still in use. Only
78 * a count of 1 means that it is free but
79 * needs to be unmapped
80 */
81 if (pkmap_count[i] != 1)
82 continue;
83 pkmap_count[i] = 0;
84
85 /* sanity check */
86 if (pte_none(pkmap_page_table[i]))
87 BUG();
88
89 /*
90 * Don't need an atomic fetch-and-clear op here;
91 * no-one has the page mapped, and cannot get at
92 * its virtual address (and hence PTE) without first
93 * getting the kmap_lock (which is held here).
94 * So no dangers, even with speculative execution.
95 */
96 page = pte_page(pkmap_page_table[i]);
97 pte_clear(&init_mm, (unsigned long)page_address(page),
98 &pkmap_page_table[i]);
99
100 set_page_address(page, NULL);
101 }
102 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
103 }
104
105 static inline unsigned long map_new_virtual(struct page *page)
106 {
107 unsigned long vaddr;
108 int count;
109
110 start:
111 count = LAST_PKMAP;
112 /* Find an empty entry */
113 for (;;) {
114 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
115 if (!last_pkmap_nr) {
116 flush_all_zero_pkmaps();
117 count = LAST_PKMAP;
118 }
119 if (!pkmap_count[last_pkmap_nr])
120 break; /* Found a usable entry */
121 if (--count)
122 continue;
123
124 /*
125 * Sleep for somebody else to unmap their entries
126 */
127 {
128 DECLARE_WAITQUEUE(wait, current);
129
130 __set_current_state(TASK_UNINTERRUPTIBLE);
131 add_wait_queue(&pkmap_map_wait, &wait);
132 spin_unlock(&kmap_lock);
133 schedule();
134 remove_wait_queue(&pkmap_map_wait, &wait);
135 spin_lock(&kmap_lock);
136
137 /* Somebody else might have mapped it while we slept */
138 if (page_address(page))
139 return (unsigned long)page_address(page);
140
141 /* Re-start */
142 goto start;
143 }
144 }
145 vaddr = PKMAP_ADDR(last_pkmap_nr);
146 set_pte_at(&init_mm, vaddr,
147 &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
148
149 pkmap_count[last_pkmap_nr] = 1;
150 set_page_address(page, (void *)vaddr);
151
152 return vaddr;
153 }
154
155 void fastcall *kmap_high(struct page *page)
156 {
157 unsigned long vaddr;
158
159 /*
160 * For highmem pages, we can't trust "virtual" until
161 * after we have the lock.
162 *
163 * We cannot call this from interrupts, as it may block
164 */
165 spin_lock(&kmap_lock);
166 vaddr = (unsigned long)page_address(page);
167 if (!vaddr)
168 vaddr = map_new_virtual(page);
169 pkmap_count[PKMAP_NR(vaddr)]++;
170 if (pkmap_count[PKMAP_NR(vaddr)] < 2)
171 BUG();
172 spin_unlock(&kmap_lock);
173 return (void*) vaddr;
174 }
175
176 EXPORT_SYMBOL(kmap_high);
177
178 void fastcall kunmap_high(struct page *page)
179 {
180 unsigned long vaddr;
181 unsigned long nr;
182 int need_wakeup;
183
184 spin_lock(&kmap_lock);
185 vaddr = (unsigned long)page_address(page);
186 if (!vaddr)
187 BUG();
188 nr = PKMAP_NR(vaddr);
189
190 /*
191 * A count must never go down to zero
192 * without a TLB flush!
193 */
194 need_wakeup = 0;
195 switch (--pkmap_count[nr]) {
196 case 0:
197 BUG();
198 case 1:
199 /*
200 * Avoid an unnecessary wake_up() function call.
201 * The common case is pkmap_count[] == 1, but
202 * no waiters.
203 * The tasks queued in the wait-queue are guarded
204 * by both the lock in the wait-queue-head and by
205 * the kmap_lock. As the kmap_lock is held here,
206 * no need for the wait-queue-head's lock. Simply
207 * test if the queue is empty.
208 */
209 need_wakeup = waitqueue_active(&pkmap_map_wait);
210 }
211 spin_unlock(&kmap_lock);
212
213 /* do wake-up, if needed, race-free outside of the spin lock */
214 if (need_wakeup)
215 wake_up(&pkmap_map_wait);
216 }
217
218 EXPORT_SYMBOL(kunmap_high);
219
220 #define POOL_SIZE 64
221
222 static __init int init_emergency_pool(void)
223 {
224 struct sysinfo i;
225 si_meminfo(&i);
226 si_swapinfo(&i);
227
228 if (!i.totalhigh)
229 return 0;
230
231 page_pool = mempool_create(POOL_SIZE, page_pool_alloc, page_pool_free, NULL);
232 if (!page_pool)
233 BUG();
234 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
235
236 return 0;
237 }
238
239 __initcall(init_emergency_pool);
240
241 /*
242 * highmem version, map in to vec
243 */
244 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
245 {
246 unsigned long flags;
247 unsigned char *vto;
248
249 local_irq_save(flags);
250 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
251 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
252 kunmap_atomic(vto, KM_BOUNCE_READ);
253 local_irq_restore(flags);
254 }
255
256 #else /* CONFIG_HIGHMEM */
257
258 #define bounce_copy_vec(to, vfrom) \
259 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
260
261 #endif
262
263 #define ISA_POOL_SIZE 16
264
265 /*
266 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
267 * as the max address, so check if the pool has already been created.
268 */
269 int init_emergency_isa_pool(void)
270 {
271 if (isa_page_pool)
272 return 0;
273
274 isa_page_pool = mempool_create(ISA_POOL_SIZE, page_pool_alloc_isa, page_pool_free, NULL);
275 if (!isa_page_pool)
276 BUG();
277
278 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
279 return 0;
280 }
281
282 /*
283 * Simple bounce buffer support for highmem pages. Depending on the
284 * queue gfp mask set, *to may or may not be a highmem page. kmap it
285 * always, it will do the Right Thing
286 */
287 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
288 {
289 unsigned char *vfrom;
290 struct bio_vec *tovec, *fromvec;
291 int i;
292
293 __bio_for_each_segment(tovec, to, i, 0) {
294 fromvec = from->bi_io_vec + i;
295
296 /*
297 * not bounced
298 */
299 if (tovec->bv_page == fromvec->bv_page)
300 continue;
301
302 /*
303 * fromvec->bv_offset and fromvec->bv_len might have been
304 * modified by the block layer, so use the original copy,
305 * bounce_copy_vec already uses tovec->bv_len
306 */
307 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
308
309 flush_dcache_page(tovec->bv_page);
310 bounce_copy_vec(tovec, vfrom);
311 }
312 }
313
314 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
315 {
316 struct bio *bio_orig = bio->bi_private;
317 struct bio_vec *bvec, *org_vec;
318 int i;
319
320 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
321 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
322
323 /*
324 * free up bounce indirect pages used
325 */
326 __bio_for_each_segment(bvec, bio, i, 0) {
327 org_vec = bio_orig->bi_io_vec + i;
328 if (bvec->bv_page == org_vec->bv_page)
329 continue;
330
331 mempool_free(bvec->bv_page, pool);
332 dec_page_state(nr_bounce);
333 }
334
335 bio_endio(bio_orig, bio_orig->bi_size, err);
336 bio_put(bio);
337 }
338
339 static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done,int err)
340 {
341 if (bio->bi_size)
342 return 1;
343
344 bounce_end_io(bio, page_pool, err);
345 return 0;
346 }
347
348 static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err)
349 {
350 if (bio->bi_size)
351 return 1;
352
353 bounce_end_io(bio, isa_page_pool, err);
354 return 0;
355 }
356
357 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
358 {
359 struct bio *bio_orig = bio->bi_private;
360
361 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
362 copy_to_high_bio_irq(bio_orig, bio);
363
364 bounce_end_io(bio, pool, err);
365 }
366
367 static int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
368 {
369 if (bio->bi_size)
370 return 1;
371
372 __bounce_end_io_read(bio, page_pool, err);
373 return 0;
374 }
375
376 static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err)
377 {
378 if (bio->bi_size)
379 return 1;
380
381 __bounce_end_io_read(bio, isa_page_pool, err);
382 return 0;
383 }
384
385 static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig,
386 mempool_t *pool)
387 {
388 struct page *page;
389 struct bio *bio = NULL;
390 int i, rw = bio_data_dir(*bio_orig);
391 struct bio_vec *to, *from;
392
393 bio_for_each_segment(from, *bio_orig, i) {
394 page = from->bv_page;
395
396 /*
397 * is destination page below bounce pfn?
398 */
399 if (page_to_pfn(page) < q->bounce_pfn)
400 continue;
401
402 /*
403 * irk, bounce it
404 */
405 if (!bio)
406 bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
407
408 to = bio->bi_io_vec + i;
409
410 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
411 to->bv_len = from->bv_len;
412 to->bv_offset = from->bv_offset;
413 inc_page_state(nr_bounce);
414
415 if (rw == WRITE) {
416 char *vto, *vfrom;
417
418 flush_dcache_page(from->bv_page);
419 vto = page_address(to->bv_page) + to->bv_offset;
420 vfrom = kmap(from->bv_page) + from->bv_offset;
421 memcpy(vto, vfrom, to->bv_len);
422 kunmap(from->bv_page);
423 }
424 }
425
426 /*
427 * no pages bounced
428 */
429 if (!bio)
430 return;
431
432 /*
433 * at least one page was bounced, fill in possible non-highmem
434 * pages
435 */
436 __bio_for_each_segment(from, *bio_orig, i, 0) {
437 to = bio_iovec_idx(bio, i);
438 if (!to->bv_page) {
439 to->bv_page = from->bv_page;
440 to->bv_len = from->bv_len;
441 to->bv_offset = from->bv_offset;
442 }
443 }
444
445 bio->bi_bdev = (*bio_orig)->bi_bdev;
446 bio->bi_flags |= (1 << BIO_BOUNCED);
447 bio->bi_sector = (*bio_orig)->bi_sector;
448 bio->bi_rw = (*bio_orig)->bi_rw;
449
450 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
451 bio->bi_idx = (*bio_orig)->bi_idx;
452 bio->bi_size = (*bio_orig)->bi_size;
453
454 if (pool == page_pool) {
455 bio->bi_end_io = bounce_end_io_write;
456 if (rw == READ)
457 bio->bi_end_io = bounce_end_io_read;
458 } else {
459 bio->bi_end_io = bounce_end_io_write_isa;
460 if (rw == READ)
461 bio->bi_end_io = bounce_end_io_read_isa;
462 }
463
464 bio->bi_private = *bio_orig;
465 *bio_orig = bio;
466 }
467
468 void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig)
469 {
470 mempool_t *pool;
471
472 /*
473 * for non-isa bounce case, just check if the bounce pfn is equal
474 * to or bigger than the highest pfn in the system -- in that case,
475 * don't waste time iterating over bio segments
476 */
477 if (!(q->bounce_gfp & GFP_DMA)) {
478 if (q->bounce_pfn >= blk_max_pfn)
479 return;
480 pool = page_pool;
481 } else {
482 BUG_ON(!isa_page_pool);
483 pool = isa_page_pool;
484 }
485
486 /*
487 * slow path
488 */
489 __blk_queue_bounce(q, bio_orig, pool);
490 }
491
492 EXPORT_SYMBOL(blk_queue_bounce);
493
494 #if defined(HASHED_PAGE_VIRTUAL)
495
496 #define PA_HASH_ORDER 7
497
498 /*
499 * Describes one page->virtual association
500 */
501 struct page_address_map {
502 struct page *page;
503 void *virtual;
504 struct list_head list;
505 };
506
507 /*
508 * page_address_map freelist, allocated from page_address_maps.
509 */
510 static struct list_head page_address_pool; /* freelist */
511 static spinlock_t pool_lock; /* protects page_address_pool */
512
513 /*
514 * Hash table bucket
515 */
516 static struct page_address_slot {
517 struct list_head lh; /* List of page_address_maps */
518 spinlock_t lock; /* Protect this bucket's list */
519 } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
520
521 static struct page_address_slot *page_slot(struct page *page)
522 {
523 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
524 }
525
526 void *page_address(struct page *page)
527 {
528 unsigned long flags;
529 void *ret;
530 struct page_address_slot *pas;
531
532 if (!PageHighMem(page))
533 return lowmem_page_address(page);
534
535 pas = page_slot(page);
536 ret = NULL;
537 spin_lock_irqsave(&pas->lock, flags);
538 if (!list_empty(&pas->lh)) {
539 struct page_address_map *pam;
540
541 list_for_each_entry(pam, &pas->lh, list) {
542 if (pam->page == page) {
543 ret = pam->virtual;
544 goto done;
545 }
546 }
547 }
548 done:
549 spin_unlock_irqrestore(&pas->lock, flags);
550 return ret;
551 }
552
553 EXPORT_SYMBOL(page_address);
554
555 void set_page_address(struct page *page, void *virtual)
556 {
557 unsigned long flags;
558 struct page_address_slot *pas;
559 struct page_address_map *pam;
560
561 BUG_ON(!PageHighMem(page));
562
563 pas = page_slot(page);
564 if (virtual) { /* Add */
565 BUG_ON(list_empty(&page_address_pool));
566
567 spin_lock_irqsave(&pool_lock, flags);
568 pam = list_entry(page_address_pool.next,
569 struct page_address_map, list);
570 list_del(&pam->list);
571 spin_unlock_irqrestore(&pool_lock, flags);
572
573 pam->page = page;
574 pam->virtual = virtual;
575
576 spin_lock_irqsave(&pas->lock, flags);
577 list_add_tail(&pam->list, &pas->lh);
578 spin_unlock_irqrestore(&pas->lock, flags);
579 } else { /* Remove */
580 spin_lock_irqsave(&pas->lock, flags);
581 list_for_each_entry(pam, &pas->lh, list) {
582 if (pam->page == page) {
583 list_del(&pam->list);
584 spin_unlock_irqrestore(&pas->lock, flags);
585 spin_lock_irqsave(&pool_lock, flags);
586 list_add_tail(&pam->list, &page_address_pool);
587 spin_unlock_irqrestore(&pool_lock, flags);
588 goto done;
589 }
590 }
591 spin_unlock_irqrestore(&pas->lock, flags);
592 }
593 done:
594 return;
595 }
596
597 static struct page_address_map page_address_maps[LAST_PKMAP];
598
599 void __init page_address_init(void)
600 {
601 int i;
602
603 INIT_LIST_HEAD(&page_address_pool);
604 for (i = 0; i < ARRAY_SIZE(page_address_maps); i++)
605 list_add(&page_address_maps[i].list, &page_address_pool);
606 for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
607 INIT_LIST_HEAD(&page_address_htable[i].lh);
608 spin_lock_init(&page_address_htable[i].lock);
609 }
610 spin_lock_init(&pool_lock);
611 }
612
613 #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */