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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /mm/highmem.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'mm/highmem.c')
-rw-r--r--mm/highmem.c607
1 files changed, 607 insertions, 0 deletions
diff --git a/mm/highmem.c b/mm/highmem.c
new file mode 100644
index 000000000000..d01276506b00
--- /dev/null
+++ b/mm/highmem.c
@@ -0,0 +1,607 @@
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
31static mempool_t *page_pool, *isa_page_pool;
32
33static void *page_pool_alloc(unsigned int __nocast gfp_mask, void *data)
34{
35 unsigned int gfp = gfp_mask | (unsigned int) (long) data;
36
37 return alloc_page(gfp);
38}
39
40static 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
54static int pkmap_count[LAST_PKMAP];
55static unsigned int last_pkmap_nr;
56static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
57
58pte_t * pkmap_page_table;
59
60static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
61
62static 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(&init_mm, (unsigned long)page_address(page),
94 &pkmap_page_table[i]);
95
96 set_page_address(page, NULL);
97 }
98 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
99}
100
101static inline unsigned long map_new_virtual(struct page *page)
102{
103 unsigned long vaddr;
104 int count;
105
106start:
107 count = LAST_PKMAP;
108 /* Find an empty entry */
109 for (;;) {
110 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
111 if (!last_pkmap_nr) {
112 flush_all_zero_pkmaps();
113 count = LAST_PKMAP;
114 }
115 if (!pkmap_count[last_pkmap_nr])
116 break; /* Found a usable entry */
117 if (--count)
118 continue;
119
120 /*
121 * Sleep for somebody else to unmap their entries
122 */
123 {
124 DECLARE_WAITQUEUE(wait, current);
125
126 __set_current_state(TASK_UNINTERRUPTIBLE);
127 add_wait_queue(&pkmap_map_wait, &wait);
128 spin_unlock(&kmap_lock);
129 schedule();
130 remove_wait_queue(&pkmap_map_wait, &wait);
131 spin_lock(&kmap_lock);
132
133 /* Somebody else might have mapped it while we slept */
134 if (page_address(page))
135 return (unsigned long)page_address(page);
136
137 /* Re-start */
138 goto start;
139 }
140 }
141 vaddr = PKMAP_ADDR(last_pkmap_nr);
142 set_pte_at(&init_mm, vaddr,
143 &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
144
145 pkmap_count[last_pkmap_nr] = 1;
146 set_page_address(page, (void *)vaddr);
147
148 return vaddr;
149}
150
151void fastcall *kmap_high(struct page *page)
152{
153 unsigned long vaddr;
154
155 /*
156 * For highmem pages, we can't trust "virtual" until
157 * after we have the lock.
158 *
159 * We cannot call this from interrupts, as it may block
160 */
161 spin_lock(&kmap_lock);
162 vaddr = (unsigned long)page_address(page);
163 if (!vaddr)
164 vaddr = map_new_virtual(page);
165 pkmap_count[PKMAP_NR(vaddr)]++;
166 if (pkmap_count[PKMAP_NR(vaddr)] < 2)
167 BUG();
168 spin_unlock(&kmap_lock);
169 return (void*) vaddr;
170}
171
172EXPORT_SYMBOL(kmap_high);
173
174void fastcall kunmap_high(struct page *page)
175{
176 unsigned long vaddr;
177 unsigned long nr;
178 int need_wakeup;
179
180 spin_lock(&kmap_lock);
181 vaddr = (unsigned long)page_address(page);
182 if (!vaddr)
183 BUG();
184 nr = PKMAP_NR(vaddr);
185
186 /*
187 * A count must never go down to zero
188 * without a TLB flush!
189 */
190 need_wakeup = 0;
191 switch (--pkmap_count[nr]) {
192 case 0:
193 BUG();
194 case 1:
195 /*
196 * Avoid an unnecessary wake_up() function call.
197 * The common case is pkmap_count[] == 1, but
198 * no waiters.
199 * The tasks queued in the wait-queue are guarded
200 * by both the lock in the wait-queue-head and by
201 * the kmap_lock. As the kmap_lock is held here,
202 * no need for the wait-queue-head's lock. Simply
203 * test if the queue is empty.
204 */
205 need_wakeup = waitqueue_active(&pkmap_map_wait);
206 }
207 spin_unlock(&kmap_lock);
208
209 /* do wake-up, if needed, race-free outside of the spin lock */
210 if (need_wakeup)
211 wake_up(&pkmap_map_wait);
212}
213
214EXPORT_SYMBOL(kunmap_high);
215
216#define POOL_SIZE 64
217
218static __init int init_emergency_pool(void)
219{
220 struct sysinfo i;
221 si_meminfo(&i);
222 si_swapinfo(&i);
223
224 if (!i.totalhigh)
225 return 0;
226
227 page_pool = mempool_create(POOL_SIZE, page_pool_alloc, page_pool_free, NULL);
228 if (!page_pool)
229 BUG();
230 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
231
232 return 0;
233}
234
235__initcall(init_emergency_pool);
236
237/*
238 * highmem version, map in to vec
239 */
240static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
241{
242 unsigned long flags;
243 unsigned char *vto;
244
245 local_irq_save(flags);
246 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
247 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
248 kunmap_atomic(vto, KM_BOUNCE_READ);
249 local_irq_restore(flags);
250}
251
252#else /* CONFIG_HIGHMEM */
253
254#define bounce_copy_vec(to, vfrom) \
255 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
256
257#endif
258
259#define ISA_POOL_SIZE 16
260
261/*
262 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
263 * as the max address, so check if the pool has already been created.
264 */
265int init_emergency_isa_pool(void)
266{
267 if (isa_page_pool)
268 return 0;
269
270 isa_page_pool = mempool_create(ISA_POOL_SIZE, page_pool_alloc, page_pool_free, (void *) __GFP_DMA);
271 if (!isa_page_pool)
272 BUG();
273
274 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
275 return 0;
276}
277
278/*
279 * Simple bounce buffer support for highmem pages. Depending on the
280 * queue gfp mask set, *to may or may not be a highmem page. kmap it
281 * always, it will do the Right Thing
282 */
283static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
284{
285 unsigned char *vfrom;
286 struct bio_vec *tovec, *fromvec;
287 int i;
288
289 __bio_for_each_segment(tovec, to, i, 0) {
290 fromvec = from->bi_io_vec + i;
291
292 /*
293 * not bounced
294 */
295 if (tovec->bv_page == fromvec->bv_page)
296 continue;
297
298 /*
299 * fromvec->bv_offset and fromvec->bv_len might have been
300 * modified by the block layer, so use the original copy,
301 * bounce_copy_vec already uses tovec->bv_len
302 */
303 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
304
305 flush_dcache_page(tovec->bv_page);
306 bounce_copy_vec(tovec, vfrom);
307 }
308}
309
310static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
311{
312 struct bio *bio_orig = bio->bi_private;
313 struct bio_vec *bvec, *org_vec;
314 int i;
315
316 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
317 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
318
319 /*
320 * free up bounce indirect pages used
321 */
322 __bio_for_each_segment(bvec, bio, i, 0) {
323 org_vec = bio_orig->bi_io_vec + i;
324 if (bvec->bv_page == org_vec->bv_page)
325 continue;
326
327 mempool_free(bvec->bv_page, pool);
328 }
329
330 bio_endio(bio_orig, bio_orig->bi_size, err);
331 bio_put(bio);
332}
333
334static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done,int err)
335{
336 if (bio->bi_size)
337 return 1;
338
339 bounce_end_io(bio, page_pool, err);
340 return 0;
341}
342
343static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err)
344{
345 if (bio->bi_size)
346 return 1;
347
348 bounce_end_io(bio, isa_page_pool, err);
349 return 0;
350}
351
352static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
353{
354 struct bio *bio_orig = bio->bi_private;
355
356 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
357 copy_to_high_bio_irq(bio_orig, bio);
358
359 bounce_end_io(bio, pool, err);
360}
361
362static int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
363{
364 if (bio->bi_size)
365 return 1;
366
367 __bounce_end_io_read(bio, page_pool, err);
368 return 0;
369}
370
371static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err)
372{
373 if (bio->bi_size)
374 return 1;
375
376 __bounce_end_io_read(bio, isa_page_pool, err);
377 return 0;
378}
379
380static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig,
381 mempool_t *pool)
382{
383 struct page *page;
384 struct bio *bio = NULL;
385 int i, rw = bio_data_dir(*bio_orig);
386 struct bio_vec *to, *from;
387
388 bio_for_each_segment(from, *bio_orig, i) {
389 page = from->bv_page;
390
391 /*
392 * is destination page below bounce pfn?
393 */
394 if (page_to_pfn(page) < q->bounce_pfn)
395 continue;
396
397 /*
398 * irk, bounce it
399 */
400 if (!bio)
401 bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
402
403 to = bio->bi_io_vec + i;
404
405 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
406 to->bv_len = from->bv_len;
407 to->bv_offset = from->bv_offset;
408
409 if (rw == WRITE) {
410 char *vto, *vfrom;
411
412 flush_dcache_page(from->bv_page);
413 vto = page_address(to->bv_page) + to->bv_offset;
414 vfrom = kmap(from->bv_page) + from->bv_offset;
415 memcpy(vto, vfrom, to->bv_len);
416 kunmap(from->bv_page);
417 }
418 }
419
420 /*
421 * no pages bounced
422 */
423 if (!bio)
424 return;
425
426 /*
427 * at least one page was bounced, fill in possible non-highmem
428 * pages
429 */
430 __bio_for_each_segment(from, *bio_orig, i, 0) {
431 to = bio_iovec_idx(bio, i);
432 if (!to->bv_page) {
433 to->bv_page = from->bv_page;
434 to->bv_len = from->bv_len;
435 to->bv_offset = from->bv_offset;
436 }
437 }
438
439 bio->bi_bdev = (*bio_orig)->bi_bdev;
440 bio->bi_flags |= (1 << BIO_BOUNCED);
441 bio->bi_sector = (*bio_orig)->bi_sector;
442 bio->bi_rw = (*bio_orig)->bi_rw;
443
444 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
445 bio->bi_idx = (*bio_orig)->bi_idx;
446 bio->bi_size = (*bio_orig)->bi_size;
447
448 if (pool == page_pool) {
449 bio->bi_end_io = bounce_end_io_write;
450 if (rw == READ)
451 bio->bi_end_io = bounce_end_io_read;
452 } else {
453 bio->bi_end_io = bounce_end_io_write_isa;
454 if (rw == READ)
455 bio->bi_end_io = bounce_end_io_read_isa;
456 }
457
458 bio->bi_private = *bio_orig;
459 *bio_orig = bio;
460}
461
462void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig)
463{
464 mempool_t *pool;
465
466 /*
467 * for non-isa bounce case, just check if the bounce pfn is equal
468 * to or bigger than the highest pfn in the system -- in that case,
469 * don't waste time iterating over bio segments
470 */
471 if (!(q->bounce_gfp & GFP_DMA)) {
472 if (q->bounce_pfn >= blk_max_pfn)
473 return;
474 pool = page_pool;
475 } else {
476 BUG_ON(!isa_page_pool);
477 pool = isa_page_pool;
478 }
479
480 /*
481 * slow path
482 */
483 __blk_queue_bounce(q, bio_orig, pool);
484}
485
486EXPORT_SYMBOL(blk_queue_bounce);
487
488#if defined(HASHED_PAGE_VIRTUAL)
489
490#define PA_HASH_ORDER 7
491
492/*
493 * Describes one page->virtual association
494 */
495struct page_address_map {
496 struct page *page;
497 void *virtual;
498 struct list_head list;
499};
500
501/*
502 * page_address_map freelist, allocated from page_address_maps.
503 */
504static struct list_head page_address_pool; /* freelist */
505static spinlock_t pool_lock; /* protects page_address_pool */
506
507/*
508 * Hash table bucket
509 */
510static struct page_address_slot {
511 struct list_head lh; /* List of page_address_maps */
512 spinlock_t lock; /* Protect this bucket's list */
513} ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
514
515static struct page_address_slot *page_slot(struct page *page)
516{
517 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
518}
519
520void *page_address(struct page *page)
521{
522 unsigned long flags;
523 void *ret;
524 struct page_address_slot *pas;
525
526 if (!PageHighMem(page))
527 return lowmem_page_address(page);
528
529 pas = page_slot(page);
530 ret = NULL;
531 spin_lock_irqsave(&pas->lock, flags);
532 if (!list_empty(&pas->lh)) {
533 struct page_address_map *pam;
534
535 list_for_each_entry(pam, &pas->lh, list) {
536 if (pam->page == page) {
537 ret = pam->virtual;
538 goto done;
539 }
540 }
541 }
542done:
543 spin_unlock_irqrestore(&pas->lock, flags);
544 return ret;
545}
546
547EXPORT_SYMBOL(page_address);
548
549void set_page_address(struct page *page, void *virtual)
550{
551 unsigned long flags;
552 struct page_address_slot *pas;
553 struct page_address_map *pam;
554
555 BUG_ON(!PageHighMem(page));
556
557 pas = page_slot(page);
558 if (virtual) { /* Add */
559 BUG_ON(list_empty(&page_address_pool));
560
561 spin_lock_irqsave(&pool_lock, flags);
562 pam = list_entry(page_address_pool.next,
563 struct page_address_map, list);
564 list_del(&pam->list);
565 spin_unlock_irqrestore(&pool_lock, flags);
566
567 pam->page = page;
568 pam->virtual = virtual;
569
570 spin_lock_irqsave(&pas->lock, flags);
571 list_add_tail(&pam->list, &pas->lh);
572 spin_unlock_irqrestore(&pas->lock, flags);
573 } else { /* Remove */
574 spin_lock_irqsave(&pas->lock, flags);
575 list_for_each_entry(pam, &pas->lh, list) {
576 if (pam->page == page) {
577 list_del(&pam->list);
578 spin_unlock_irqrestore(&pas->lock, flags);
579 spin_lock_irqsave(&pool_lock, flags);
580 list_add_tail(&pam->list, &page_address_pool);
581 spin_unlock_irqrestore(&pool_lock, flags);
582 goto done;
583 }
584 }
585 spin_unlock_irqrestore(&pas->lock, flags);
586 }
587done:
588 return;
589}
590
591static struct page_address_map page_address_maps[LAST_PKMAP];
592
593void __init page_address_init(void)
594{
595 int i;
596
597 INIT_LIST_HEAD(&page_address_pool);
598 for (i = 0; i < ARRAY_SIZE(page_address_maps); i++)
599 list_add(&page_address_maps[i].list, &page_address_pool);
600 for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
601 INIT_LIST_HEAD(&page_address_htable[i].lh);
602 spin_lock_init(&page_address_htable[i].lock);
603 }
604 spin_lock_init(&pool_lock);
605}
606
607#endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */