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/blktrace_api.h>
30 #include <asm/tlbflush.h>
31
32 static mempool_t *page_pool, *isa_page_pool;
33
34 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
35 {
36 return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
37 }
38
39 /*
40 * Virtual_count is not a pure "count".
41 * 0 means that it is not mapped, and has not been mapped
42 * since a TLB flush - it is usable.
43 * 1 means that there are no users, but it has been mapped
44 * since the last TLB flush - so we can't use it.
45 * n means that there are (n-1) current users of it.
46 */
47 #ifdef CONFIG_HIGHMEM
48
49 static int pkmap_count[LAST_PKMAP];
50 static unsigned int last_pkmap_nr;
51 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
52
53 pte_t * pkmap_page_table;
54
55 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
56
57 static void flush_all_zero_pkmaps(void)
58 {
59 int i;
60
61 flush_cache_kmaps();
62
63 for (i = 0; i < LAST_PKMAP; i++) {
64 struct page *page;
65
66 /*
67 * zero means we don't have anything to do,
68 * >1 means that it is still in use. Only
69 * a count of 1 means that it is free but
70 * needs to be unmapped
71 */
72 if (pkmap_count[i] != 1)
73 continue;
74 pkmap_count[i] = 0;
75
76 /* sanity check */
77 BUG_ON(pte_none(pkmap_page_table[i]));
78
79 /*
80 * Don't need an atomic fetch-and-clear op here;
81 * no-one has the page mapped, and cannot get at
82 * its virtual address (and hence PTE) without first
83 * getting the kmap_lock (which is held here).
84 * So no dangers, even with speculative execution.
85 */
86 page = pte_page(pkmap_page_table[i]);
87 pte_clear(&init_mm, (unsigned long)page_address(page),
88 &pkmap_page_table[i]);
89
90 set_page_address(page, NULL);
91 }
92 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
93 }
94
95 static inline unsigned long map_new_virtual(struct page *page)
96 {
97 unsigned long vaddr;
98 int count;
99
100 start:
101 count = LAST_PKMAP;
102 /* Find an empty entry */
103 for (;;) {
104 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
105 if (!last_pkmap_nr) {
106 flush_all_zero_pkmaps();
107 count = LAST_PKMAP;
108 }
109 if (!pkmap_count[last_pkmap_nr])
110 break; /* Found a usable entry */
111 if (--count)
112 continue;
113
114 /*
115 * Sleep for somebody else to unmap their entries
116 */
117 {
118 DECLARE_WAITQUEUE(wait, current);
119
120 __set_current_state(TASK_UNINTERRUPTIBLE);
121 add_wait_queue(&pkmap_map_wait, &wait);
122 spin_unlock(&kmap_lock);
123 schedule();
124 remove_wait_queue(&pkmap_map_wait, &wait);
125 spin_lock(&kmap_lock);
126
127 /* Somebody else might have mapped it while we slept */
128 if (page_address(page))
129 return (unsigned long)page_address(page);
130
131 /* Re-start */
132 goto start;
133 }
134 }
135 vaddr = PKMAP_ADDR(last_pkmap_nr);
136 set_pte_at(&init_mm, vaddr,
137 &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
138
139 pkmap_count[last_pkmap_nr] = 1;
140 set_page_address(page, (void *)vaddr);
141
142 return vaddr;
143 }
144
145 void fastcall *kmap_high(struct page *page)
146 {
147 unsigned long vaddr;
148
149 /*
150 * For highmem pages, we can't trust "virtual" until
151 * after we have the lock.
152 *
153 * We cannot call this from interrupts, as it may block
154 */
155 spin_lock(&kmap_lock);
156 vaddr = (unsigned long)page_address(page);
157 if (!vaddr)
158 vaddr = map_new_virtual(page);
159 pkmap_count[PKMAP_NR(vaddr)]++;
160 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
161 spin_unlock(&kmap_lock);
162 return (void*) vaddr;
163 }
164
165 EXPORT_SYMBOL(kmap_high);
166
167 void fastcall kunmap_high(struct page *page)
168 {
169 unsigned long vaddr;
170 unsigned long nr;
171 int need_wakeup;
172
173 spin_lock(&kmap_lock);
174 vaddr = (unsigned long)page_address(page);
175 BUG_ON(!vaddr);
176 nr = PKMAP_NR(vaddr);
177
178 /*
179 * A count must never go down to zero
180 * without a TLB flush!
181 */
182 need_wakeup = 0;
183 switch (--pkmap_count[nr]) {
184 case 0:
185 BUG();
186 case 1:
187 /*
188 * Avoid an unnecessary wake_up() function call.
189 * The common case is pkmap_count[] == 1, but
190 * no waiters.
191 * The tasks queued in the wait-queue are guarded
192 * by both the lock in the wait-queue-head and by
193 * the kmap_lock. As the kmap_lock is held here,
194 * no need for the wait-queue-head's lock. Simply
195 * test if the queue is empty.
196 */
197 need_wakeup = waitqueue_active(&pkmap_map_wait);
198 }
199 spin_unlock(&kmap_lock);
200
201 /* do wake-up, if needed, race-free outside of the spin lock */
202 if (need_wakeup)
203 wake_up(&pkmap_map_wait);
204 }
205
206 EXPORT_SYMBOL(kunmap_high);
207
208 #define POOL_SIZE 64
209
210 static __init int init_emergency_pool(void)
211 {
212 struct sysinfo i;
213 si_meminfo(&i);
214 si_swapinfo(&i);
215
216 if (!i.totalhigh)
217 return 0;
218
219 page_pool = mempool_create_page_pool(POOL_SIZE, 0);
220 BUG_ON(!page_pool);
221 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
222
223 return 0;
224 }
225
226 __initcall(init_emergency_pool);
227
228 /*
229 * highmem version, map in to vec
230 */
231 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
232 {
233 unsigned long flags;
234 unsigned char *vto;
235
236 local_irq_save(flags);
237 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
238 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
239 kunmap_atomic(vto, KM_BOUNCE_READ);
240 local_irq_restore(flags);
241 }
242
243 #else /* CONFIG_HIGHMEM */
244
245 #define bounce_copy_vec(to, vfrom) \
246 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
247
248 #endif
249
250 #define ISA_POOL_SIZE 16
251
252 /*
253 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
254 * as the max address, so check if the pool has already been created.
255 */
256 int init_emergency_isa_pool(void)
257 {
258 if (isa_page_pool)
259 return 0;
260
261 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
262 mempool_free_pages, (void *) 0);
263 BUG_ON(!isa_page_pool);
264
265 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
266 return 0;
267 }
268
269 /*
270 * Simple bounce buffer support for highmem pages. Depending on the
271 * queue gfp mask set, *to may or may not be a highmem page. kmap it
272 * always, it will do the Right Thing
273 */
274 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
275 {
276 unsigned char *vfrom;
277 struct bio_vec *tovec, *fromvec;
278 int i;
279
280 __bio_for_each_segment(tovec, to, i, 0) {
281 fromvec = from->bi_io_vec + i;
282
283 /*
284 * not bounced
285 */
286 if (tovec->bv_page == fromvec->bv_page)
287 continue;
288
289 /*
290 * fromvec->bv_offset and fromvec->bv_len might have been
291 * modified by the block layer, so use the original copy,
292 * bounce_copy_vec already uses tovec->bv_len
293 */
294 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
295
296 flush_dcache_page(tovec->bv_page);
297 bounce_copy_vec(tovec, vfrom);
298 }
299 }
300
301 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
302 {
303 struct bio *bio_orig = bio->bi_private;
304 struct bio_vec *bvec, *org_vec;
305 int i;
306
307 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
308 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
309
310 /*
311 * free up bounce indirect pages used
312 */
313 __bio_for_each_segment(bvec, bio, i, 0) {
314 org_vec = bio_orig->bi_io_vec + i;
315 if (bvec->bv_page == org_vec->bv_page)
316 continue;
317
318 mempool_free(bvec->bv_page, pool);
319 dec_page_state(nr_bounce);
320 }
321
322 bio_endio(bio_orig, bio_orig->bi_size, err);
323 bio_put(bio);
324 }
325
326 static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done, int err)
327 {
328 if (bio->bi_size)
329 return 1;
330
331 bounce_end_io(bio, page_pool, err);
332 return 0;
333 }
334
335 static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err)
336 {
337 if (bio->bi_size)
338 return 1;
339
340 bounce_end_io(bio, isa_page_pool, err);
341 return 0;
342 }
343
344 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
345 {
346 struct bio *bio_orig = bio->bi_private;
347
348 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
349 copy_to_high_bio_irq(bio_orig, bio);
350
351 bounce_end_io(bio, pool, err);
352 }
353
354 static int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
355 {
356 if (bio->bi_size)
357 return 1;
358
359 __bounce_end_io_read(bio, page_pool, err);
360 return 0;
361 }
362
363 static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err)
364 {
365 if (bio->bi_size)
366 return 1;
367
368 __bounce_end_io_read(bio, isa_page_pool, err);
369 return 0;
370 }
371
372 static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig,
373 mempool_t *pool)
374 {
375 struct page *page;
376 struct bio *bio = NULL;
377 int i, rw = bio_data_dir(*bio_orig);
378 struct bio_vec *to, *from;
379
380 bio_for_each_segment(from, *bio_orig, i) {
381 page = from->bv_page;
382
383 /*
384 * is destination page below bounce pfn?
385 */
386 if (page_to_pfn(page) < q->bounce_pfn)
387 continue;
388
389 /*
390 * irk, bounce it
391 */
392 if (!bio)
393 bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
394
395 to = bio->bi_io_vec + i;
396
397 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
398 to->bv_len = from->bv_len;
399 to->bv_offset = from->bv_offset;
400 inc_page_state(nr_bounce);
401
402 if (rw == WRITE) {
403 char *vto, *vfrom;
404
405 flush_dcache_page(from->bv_page);
406 vto = page_address(to->bv_page) + to->bv_offset;
407 vfrom = kmap(from->bv_page) + from->bv_offset;
408 memcpy(vto, vfrom, to->bv_len);
409 kunmap(from->bv_page);
410 }
411 }
412
413 /*
414 * no pages bounced
415 */
416 if (!bio)
417 return;
418
419 /*
420 * at least one page was bounced, fill in possible non-highmem
421 * pages
422 */
423 __bio_for_each_segment(from, *bio_orig, i, 0) {
424 to = bio_iovec_idx(bio, i);
425 if (!to->bv_page) {
426 to->bv_page = from->bv_page;
427 to->bv_len = from->bv_len;
428 to->bv_offset = from->bv_offset;
429 }
430 }
431
432 bio->bi_bdev = (*bio_orig)->bi_bdev;
433 bio->bi_flags |= (1 << BIO_BOUNCED);
434 bio->bi_sector = (*bio_orig)->bi_sector;
435 bio->bi_rw = (*bio_orig)->bi_rw;
436
437 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
438 bio->bi_idx = (*bio_orig)->bi_idx;
439 bio->bi_size = (*bio_orig)->bi_size;
440
441 if (pool == page_pool) {
442 bio->bi_end_io = bounce_end_io_write;
443 if (rw == READ)
444 bio->bi_end_io = bounce_end_io_read;
445 } else {
446 bio->bi_end_io = bounce_end_io_write_isa;
447 if (rw == READ)
448 bio->bi_end_io = bounce_end_io_read_isa;
449 }
450
451 bio->bi_private = *bio_orig;
452 *bio_orig = bio;
453 }
454
455 void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig)
456 {
457 mempool_t *pool;
458
459 /*
460 * for non-isa bounce case, just check if the bounce pfn is equal
461 * to or bigger than the highest pfn in the system -- in that case,
462 * don't waste time iterating over bio segments
463 */
464 if (!(q->bounce_gfp & GFP_DMA)) {
465 if (q->bounce_pfn >= blk_max_pfn)
466 return;
467 pool = page_pool;
468 } else {
469 BUG_ON(!isa_page_pool);
470 pool = isa_page_pool;
471 }
472
473 blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE);
474
475 /*
476 * slow path
477 */
478 __blk_queue_bounce(q, bio_orig, pool);
479 }
480
481 EXPORT_SYMBOL(blk_queue_bounce);
482
483 #if defined(HASHED_PAGE_VIRTUAL)
484
485 #define PA_HASH_ORDER 7
486
487 /*
488 * Describes one page->virtual association
489 */
490 struct page_address_map {
491 struct page *page;
492 void *virtual;
493 struct list_head list;
494 };
495
496 /*
497 * page_address_map freelist, allocated from page_address_maps.
498 */
499 static struct list_head page_address_pool; /* freelist */
500 static spinlock_t pool_lock; /* protects page_address_pool */
501
502 /*
503 * Hash table bucket
504 */
505 static struct page_address_slot {
506 struct list_head lh; /* List of page_address_maps */
507 spinlock_t lock; /* Protect this bucket's list */
508 } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
509
510 static struct page_address_slot *page_slot(struct page *page)
511 {
512 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
513 }
514
515 void *page_address(struct page *page)
516 {
517 unsigned long flags;
518 void *ret;
519 struct page_address_slot *pas;
520
521 if (!PageHighMem(page))
522 return lowmem_page_address(page);
523
524 pas = page_slot(page);
525 ret = NULL;
526 spin_lock_irqsave(&pas->lock, flags);
527 if (!list_empty(&pas->lh)) {
528 struct page_address_map *pam;
529
530 list_for_each_entry(pam, &pas->lh, list) {
531 if (pam->page == page) {
532 ret = pam->virtual;
533 goto done;
534 }
535 }
536 }
537 done:
538 spin_unlock_irqrestore(&pas->lock, flags);
539 return ret;
540 }
541
542 EXPORT_SYMBOL(page_address);
543
544 void set_page_address(struct page *page, void *virtual)
545 {
546 unsigned long flags;
547 struct page_address_slot *pas;
548 struct page_address_map *pam;
549
550 BUG_ON(!PageHighMem(page));
551
552 pas = page_slot(page);
553 if (virtual) { /* Add */
554 BUG_ON(list_empty(&page_address_pool));
555
556 spin_lock_irqsave(&pool_lock, flags);
557 pam = list_entry(page_address_pool.next,
558 struct page_address_map, list);
559 list_del(&pam->list);
560 spin_unlock_irqrestore(&pool_lock, flags);
561
562 pam->page = page;
563 pam->virtual = virtual;
564
565 spin_lock_irqsave(&pas->lock, flags);
566 list_add_tail(&pam->list, &pas->lh);
567 spin_unlock_irqrestore(&pas->lock, flags);
568 } else { /* Remove */
569 spin_lock_irqsave(&pas->lock, flags);
570 list_for_each_entry(pam, &pas->lh, list) {
571 if (pam->page == page) {
572 list_del(&pam->list);
573 spin_unlock_irqrestore(&pas->lock, flags);
574 spin_lock_irqsave(&pool_lock, flags);
575 list_add_tail(&pam->list, &page_address_pool);
576 spin_unlock_irqrestore(&pool_lock, flags);
577 goto done;
578 }
579 }
580 spin_unlock_irqrestore(&pas->lock, flags);
581 }
582 done:
583 return;
584 }
585
586 static struct page_address_map page_address_maps[LAST_PKMAP];
587
588 void __init page_address_init(void)
589 {
590 int i;
591
592 INIT_LIST_HEAD(&page_address_pool);
593 for (i = 0; i < ARRAY_SIZE(page_address_maps); i++)
594 list_add(&page_address_maps[i].list, &page_address_pool);
595 for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
596 INIT_LIST_HEAD(&page_address_htable[i].lh);
597 spin_lock_init(&page_address_htable[i].lock);
598 }
599 spin_lock_init(&pool_lock);
600 }
601
602 #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */
603
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