2 * High memory handling common code and variables.
4 * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de
5 * Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de
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.
12 * Rewrote high memory support to move the page cache into
13 * high memory. Implemented permanent (schedulable) kmaps
14 * based on Linus' idea.
16 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
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>
32 static mempool_t *page_pool, *isa_page_pool;
34 static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
36 return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
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.
49 static int pkmap_count[LAST_PKMAP];
50 static unsigned int last_pkmap_nr;
51 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
53 pte_t * pkmap_page_table;
55 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
57 static void flush_all_zero_pkmaps(void)
63 for (i = 0; i < LAST_PKMAP; i++) {
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
72 if (pkmap_count[i] != 1)
77 BUG_ON(pte_none(pkmap_page_table[i]));
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.
86 page = pte_page(pkmap_page_table[i]);
87 pte_clear(&init_mm, (unsigned long)page_address(page),
88 &pkmap_page_table[i]);
90 set_page_address(page, NULL);
92 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
95 static inline unsigned long map_new_virtual(struct page *page)
102 /* Find an empty entry */
104 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
105 if (!last_pkmap_nr) {
106 flush_all_zero_pkmaps();
109 if (!pkmap_count[last_pkmap_nr])
110 break; /* Found a usable entry */
115 * Sleep for somebody else to unmap their entries
118 DECLARE_WAITQUEUE(wait, current);
120 __set_current_state(TASK_UNINTERRUPTIBLE);
121 add_wait_queue(&pkmap_map_wait, &wait);
122 spin_unlock(&kmap_lock);
124 remove_wait_queue(&pkmap_map_wait, &wait);
125 spin_lock(&kmap_lock);
127 /* Somebody else might have mapped it while we slept */
128 if (page_address(page))
129 return (unsigned long)page_address(page);
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));
139 pkmap_count[last_pkmap_nr] = 1;
140 set_page_address(page, (void *)vaddr);
146 void kmap_flush_unused(void)
148 spin_lock(&kmap_lock);
149 flush_all_zero_pkmaps();
150 spin_unlock(&kmap_lock);
153 EXPORT_SYMBOL(kmap_flush_unused);
156 void fastcall *kmap_high(struct page *page)
161 * For highmem pages, we can't trust "virtual" until
162 * after we have the lock.
164 * We cannot call this from interrupts, as it may block
166 spin_lock(&kmap_lock);
167 vaddr = (unsigned long)page_address(page);
169 vaddr = map_new_virtual(page);
170 pkmap_count[PKMAP_NR(vaddr)]++;
171 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
172 spin_unlock(&kmap_lock);
173 return (void*) vaddr;
176 EXPORT_SYMBOL(kmap_high);
178 void fastcall kunmap_high(struct page *page)
184 spin_lock(&kmap_lock);
185 vaddr = (unsigned long)page_address(page);
187 nr = PKMAP_NR(vaddr);
190 * A count must never go down to zero
191 * without a TLB flush!
194 switch (--pkmap_count[nr]) {
199 * Avoid an unnecessary wake_up() function call.
200 * The common case is pkmap_count[] == 1, but
202 * The tasks queued in the wait-queue are guarded
203 * by both the lock in the wait-queue-head and by
204 * the kmap_lock. As the kmap_lock is held here,
205 * no need for the wait-queue-head's lock. Simply
206 * test if the queue is empty.
208 need_wakeup = waitqueue_active(&pkmap_map_wait);
210 spin_unlock(&kmap_lock);
212 /* do wake-up, if needed, race-free outside of the spin lock */
214 wake_up(&pkmap_map_wait);
217 EXPORT_SYMBOL(kunmap_high);
221 static __init int init_emergency_pool(void)
230 page_pool = mempool_create_page_pool(POOL_SIZE, 0);
232 printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
237 __initcall(init_emergency_pool);
240 * highmem version, map in to vec
242 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
247 local_irq_save(flags);
248 vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
249 memcpy(vto + to->bv_offset, vfrom, to->bv_len);
250 kunmap_atomic(vto, KM_BOUNCE_READ);
251 local_irq_restore(flags);
254 #else /* CONFIG_HIGHMEM */
256 #define bounce_copy_vec(to, vfrom) \
257 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
261 #define ISA_POOL_SIZE 16
264 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
265 * as the max address, so check if the pool has already been created.
267 int init_emergency_isa_pool(void)
272 isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
273 mempool_free_pages, (void *) 0);
274 BUG_ON(!isa_page_pool);
276 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
281 * Simple bounce buffer support for highmem pages. Depending on the
282 * queue gfp mask set, *to may or may not be a highmem page. kmap it
283 * always, it will do the Right Thing
285 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
287 unsigned char *vfrom;
288 struct bio_vec *tovec, *fromvec;
291 __bio_for_each_segment(tovec, to, i, 0) {
292 fromvec = from->bi_io_vec + i;
297 if (tovec->bv_page == fromvec->bv_page)
301 * fromvec->bv_offset and fromvec->bv_len might have been
302 * modified by the block layer, so use the original copy,
303 * bounce_copy_vec already uses tovec->bv_len
305 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
307 flush_dcache_page(tovec->bv_page);
308 bounce_copy_vec(tovec, vfrom);
312 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
314 struct bio *bio_orig = bio->bi_private;
315 struct bio_vec *bvec, *org_vec;
318 if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
319 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
322 * free up bounce indirect pages used
324 __bio_for_each_segment(bvec, bio, i, 0) {
325 org_vec = bio_orig->bi_io_vec + i;
326 if (bvec->bv_page == org_vec->bv_page)
329 mempool_free(bvec->bv_page, pool);
330 dec_page_state(nr_bounce);
333 bio_endio(bio_orig, bio_orig->bi_size, err);
337 static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done, int err)
342 bounce_end_io(bio, page_pool, err);
346 static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err)
351 bounce_end_io(bio, isa_page_pool, err);
355 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
357 struct bio *bio_orig = bio->bi_private;
359 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
360 copy_to_high_bio_irq(bio_orig, bio);
362 bounce_end_io(bio, pool, err);
365 static int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
370 __bounce_end_io_read(bio, page_pool, err);
374 static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err)
379 __bounce_end_io_read(bio, isa_page_pool, err);
383 static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig,
387 struct bio *bio = NULL;
388 int i, rw = bio_data_dir(*bio_orig);
389 struct bio_vec *to, *from;
391 bio_for_each_segment(from, *bio_orig, i) {
392 page = from->bv_page;
395 * is destination page below bounce pfn?
397 if (page_to_pfn(page) < q->bounce_pfn)
404 bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
406 to = bio->bi_io_vec + i;
408 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
409 to->bv_len = from->bv_len;
410 to->bv_offset = from->bv_offset;
411 inc_page_state(nr_bounce);
416 flush_dcache_page(from->bv_page);
417 vto = page_address(to->bv_page) + to->bv_offset;
418 vfrom = kmap(from->bv_page) + from->bv_offset;
419 memcpy(vto, vfrom, to->bv_len);
420 kunmap(from->bv_page);
431 * at least one page was bounced, fill in possible non-highmem
434 __bio_for_each_segment(from, *bio_orig, i, 0) {
435 to = bio_iovec_idx(bio, i);
437 to->bv_page = from->bv_page;
438 to->bv_len = from->bv_len;
439 to->bv_offset = from->bv_offset;
443 bio->bi_bdev = (*bio_orig)->bi_bdev;
444 bio->bi_flags |= (1 << BIO_BOUNCED);
445 bio->bi_sector = (*bio_orig)->bi_sector;
446 bio->bi_rw = (*bio_orig)->bi_rw;
448 bio->bi_vcnt = (*bio_orig)->bi_vcnt;
449 bio->bi_idx = (*bio_orig)->bi_idx;
450 bio->bi_size = (*bio_orig)->bi_size;
452 if (pool == page_pool) {
453 bio->bi_end_io = bounce_end_io_write;
455 bio->bi_end_io = bounce_end_io_read;
457 bio->bi_end_io = bounce_end_io_write_isa;
459 bio->bi_end_io = bounce_end_io_read_isa;
462 bio->bi_private = *bio_orig;
466 void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig)
471 * for non-isa bounce case, just check if the bounce pfn is equal
472 * to or bigger than the highest pfn in the system -- in that case,
473 * don't waste time iterating over bio segments
475 if (!(q->bounce_gfp & GFP_DMA)) {
476 if (q->bounce_pfn >= blk_max_pfn)
480 BUG_ON(!isa_page_pool);
481 pool = isa_page_pool;
484 blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE);
489 __blk_queue_bounce(q, bio_orig, pool);
492 EXPORT_SYMBOL(blk_queue_bounce);
494 #if defined(HASHED_PAGE_VIRTUAL)
496 #define PA_HASH_ORDER 7
499 * Describes one page->virtual association
501 struct page_address_map {
504 struct list_head list;
508 * page_address_map freelist, allocated from page_address_maps.
510 static struct list_head page_address_pool; /* freelist */
511 static spinlock_t pool_lock; /* protects page_address_pool */
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];
521 static struct page_address_slot *page_slot(struct page *page)
523 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
526 void *page_address(struct page *page)
530 struct page_address_slot *pas;
532 if (!PageHighMem(page))
533 return lowmem_page_address(page);
535 pas = page_slot(page);
537 spin_lock_irqsave(&pas->lock, flags);
538 if (!list_empty(&pas->lh)) {
539 struct page_address_map *pam;
541 list_for_each_entry(pam, &pas->lh, list) {
542 if (pam->page == page) {
549 spin_unlock_irqrestore(&pas->lock, flags);
553 EXPORT_SYMBOL(page_address);
555 void set_page_address(struct page *page, void *virtual)
558 struct page_address_slot *pas;
559 struct page_address_map *pam;
561 BUG_ON(!PageHighMem(page));
563 pas = page_slot(page);
564 if (virtual) { /* Add */
565 BUG_ON(list_empty(&page_address_pool));
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);
574 pam->virtual = virtual;
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);
591 spin_unlock_irqrestore(&pas->lock, flags);
597 static struct page_address_map page_address_maps[LAST_PKMAP];
599 void __init page_address_init(void)
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);
610 spin_lock_init(&pool_lock);
613 #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */