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 <asm/tlbflush.h>
31 static mempool_t
*page_pool
, *isa_page_pool
;
33 static void *page_pool_alloc(int gfp_mask
, void *data
)
35 int gfp
= gfp_mask
| (int) (long) data
;
37 return alloc_page(gfp
);
40 static void page_pool_free(void *page
, void *data
)
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.
54 static int pkmap_count
[LAST_PKMAP
];
55 static unsigned int last_pkmap_nr
;
56 static spinlock_t kmap_lock __cacheline_aligned_in_smp
= SPIN_LOCK_UNLOCKED
;
58 pte_t
* pkmap_page_table
;
60 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait
);
62 static void flush_all_zero_pkmaps(void)
68 for (i
= 0; i
< LAST_PKMAP
; i
++) {
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
77 if (pkmap_count
[i
] != 1)
82 if (pte_none(pkmap_page_table
[i
]))
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.
92 page
= pte_page(pkmap_page_table
[i
]);
93 pte_clear(&pkmap_page_table
[i
]);
95 set_page_address(page
, NULL
);
97 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP
));
100 static inline unsigned long map_new_virtual(struct page
*page
)
107 /* Find an empty entry */
109 last_pkmap_nr
= (last_pkmap_nr
+ 1) & LAST_PKMAP_MASK
;
110 if (!last_pkmap_nr
) {
111 flush_all_zero_pkmaps();
114 if (!pkmap_count
[last_pkmap_nr
])
115 break; /* Found a usable entry */
120 * Sleep for somebody else to unmap their entries
123 DECLARE_WAITQUEUE(wait
, current
);
125 __set_current_state(TASK_UNINTERRUPTIBLE
);
126 add_wait_queue(&pkmap_map_wait
, &wait
);
127 spin_unlock(&kmap_lock
);
129 remove_wait_queue(&pkmap_map_wait
, &wait
);
130 spin_lock(&kmap_lock
);
132 /* Somebody else might have mapped it while we slept */
133 if (page_address(page
))
134 return (unsigned long)page_address(page
);
140 vaddr
= PKMAP_ADDR(last_pkmap_nr
);
141 set_pte(&(pkmap_page_table
[last_pkmap_nr
]), mk_pte(page
, kmap_prot
));
143 pkmap_count
[last_pkmap_nr
] = 1;
144 set_page_address(page
, (void *)vaddr
);
149 void fastcall
*kmap_high(struct page
*page
)
154 * For highmem pages, we can't trust "virtual" until
155 * after we have the lock.
157 * We cannot call this from interrupts, as it may block
159 spin_lock(&kmap_lock
);
160 vaddr
= (unsigned long)page_address(page
);
162 vaddr
= map_new_virtual(page
);
163 pkmap_count
[PKMAP_NR(vaddr
)]++;
164 if (pkmap_count
[PKMAP_NR(vaddr
)] < 2)
166 spin_unlock(&kmap_lock
);
167 return (void*) vaddr
;
170 EXPORT_SYMBOL(kmap_high
);
172 void fastcall
kunmap_high(struct page
*page
)
178 spin_lock(&kmap_lock
);
179 vaddr
= (unsigned long)page_address(page
);
182 nr
= PKMAP_NR(vaddr
);
185 * A count must never go down to zero
186 * without a TLB flush!
189 switch (--pkmap_count
[nr
]) {
194 * Avoid an unnecessary wake_up() function call.
195 * The common case is pkmap_count[] == 1, but
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.
203 need_wakeup
= waitqueue_active(&pkmap_map_wait
);
205 spin_unlock(&kmap_lock
);
207 /* do wake-up, if needed, race-free outside of the spin lock */
209 wake_up(&pkmap_map_wait
);
212 EXPORT_SYMBOL(kunmap_high
);
216 static __init
int init_emergency_pool(void)
225 page_pool
= mempool_create(POOL_SIZE
, page_pool_alloc
, page_pool_free
, NULL
);
228 printk("highmem bounce pool size: %d pages\n", POOL_SIZE
);
233 __initcall(init_emergency_pool
);
236 * highmem version, map in to vec
238 static void bounce_copy_vec(struct bio_vec
*to
, unsigned char *vfrom
)
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
);
250 #else /* CONFIG_HIGHMEM */
252 #define bounce_copy_vec(to, vfrom) \
253 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
257 #define ISA_POOL_SIZE 16
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.
263 int init_emergency_isa_pool(void)
268 isa_page_pool
= mempool_create(ISA_POOL_SIZE
, page_pool_alloc
, page_pool_free
, (void *) __GFP_DMA
);
272 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE
);
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
281 static void copy_to_high_bio_irq(struct bio
*to
, struct bio
*from
)
283 unsigned char *vfrom
;
284 struct bio_vec
*tovec
, *fromvec
;
287 __bio_for_each_segment(tovec
, to
, i
, 0) {
288 fromvec
= from
->bi_io_vec
+ i
;
293 if (tovec
->bv_page
== fromvec
->bv_page
)
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
301 vfrom
= page_address(fromvec
->bv_page
) + tovec
->bv_offset
;
303 flush_dcache_page(tovec
->bv_page
);
304 bounce_copy_vec(tovec
, vfrom
);
308 static void bounce_end_io(struct bio
*bio
, mempool_t
*pool
)
310 struct bio
*bio_orig
= bio
->bi_private
;
311 struct bio_vec
*bvec
, *org_vec
;
314 if (!test_bit(BIO_UPTODATE
, &bio
->bi_flags
))
318 * free up bounce indirect pages used
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
)
325 mempool_free(bvec
->bv_page
, pool
);
328 bio_endio(bio_orig
, bio_orig
->bi_size
, err
);
332 static int bounce_end_io_write(struct bio
*bio
, unsigned int bytes_done
,int err
)
337 bounce_end_io(bio
, page_pool
);
341 static int bounce_end_io_write_isa(struct bio
*bio
, unsigned int bytes_done
, int err
)
346 bounce_end_io(bio
, isa_page_pool
);
350 static void __bounce_end_io_read(struct bio
*bio
, mempool_t
*pool
)
352 struct bio
*bio_orig
= bio
->bi_private
;
354 if (test_bit(BIO_UPTODATE
, &bio
->bi_flags
))
355 copy_to_high_bio_irq(bio_orig
, bio
);
357 bounce_end_io(bio
, pool
);
360 static int bounce_end_io_read(struct bio
*bio
, unsigned int bytes_done
, int err
)
365 __bounce_end_io_read(bio
, page_pool
);
369 static int bounce_end_io_read_isa(struct bio
*bio
, unsigned int bytes_done
, int err
)
374 __bounce_end_io_read(bio
, isa_page_pool
);
378 static void __blk_queue_bounce(request_queue_t
*q
, struct bio
**bio_orig
,
382 struct bio
*bio
= NULL
;
383 int i
, rw
= bio_data_dir(*bio_orig
);
384 struct bio_vec
*to
, *from
;
386 bio_for_each_segment(from
, *bio_orig
, i
) {
387 page
= from
->bv_page
;
390 * is destination page below bounce pfn?
392 if (page_to_pfn(page
) < q
->bounce_pfn
)
399 bio
= bio_alloc(GFP_NOIO
, (*bio_orig
)->bi_vcnt
);
401 to
= bio
->bi_io_vec
+ i
;
403 to
->bv_page
= mempool_alloc(pool
, q
->bounce_gfp
);
404 to
->bv_len
= from
->bv_len
;
405 to
->bv_offset
= from
->bv_offset
;
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
);
425 * at least one page was bounced, fill in possible non-highmem
428 bio_for_each_segment(from
, *bio_orig
, i
) {
429 to
= bio_iovec_idx(bio
, i
);
431 to
->bv_page
= from
->bv_page
;
432 to
->bv_len
= from
->bv_len
;
433 to
->bv_offset
= from
->bv_offset
;
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
;
442 bio
->bi_vcnt
= (*bio_orig
)->bi_vcnt
;
443 bio
->bi_idx
= (*bio_orig
)->bi_idx
;
444 bio
->bi_size
= (*bio_orig
)->bi_size
;
446 if (pool
== page_pool
) {
447 bio
->bi_end_io
= bounce_end_io_write
;
449 bio
->bi_end_io
= bounce_end_io_read
;
451 bio
->bi_end_io
= bounce_end_io_write_isa
;
453 bio
->bi_end_io
= bounce_end_io_read_isa
;
456 bio
->bi_private
= *bio_orig
;
460 void blk_queue_bounce(request_queue_t
*q
, struct bio
**bio_orig
)
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
469 if (!(q
->bounce_gfp
& GFP_DMA
)) {
470 if (q
->bounce_pfn
>= blk_max_pfn
)
474 BUG_ON(!isa_page_pool
);
475 pool
= isa_page_pool
;
481 __blk_queue_bounce(q
, bio_orig
, pool
);
484 EXPORT_SYMBOL(blk_queue_bounce
);
486 #if defined(HASHED_PAGE_VIRTUAL)
488 #define PA_HASH_ORDER 7
491 * Describes one page->virtual association
493 struct page_address_map
{
496 struct list_head list
;
500 * page_address_map freelist, allocated from page_address_maps.
502 static struct list_head page_address_pool
; /* freelist */
503 static spinlock_t pool_lock
; /* protects page_address_pool */
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
];
513 static struct page_address_slot
*page_slot(struct page
*page
)
515 return &page_address_htable
[hash_ptr(page
, PA_HASH_ORDER
)];
518 void *page_address(struct page
*page
)
522 struct page_address_slot
*pas
;
524 if (!PageHighMem(page
))
525 return lowmem_page_address(page
);
527 pas
= page_slot(page
);
529 spin_lock_irqsave(&pas
->lock
, flags
);
530 if (!list_empty(&pas
->lh
)) {
531 struct page_address_map
*pam
;
533 list_for_each_entry(pam
, &pas
->lh
, list
) {
534 if (pam
->page
== page
) {
541 spin_unlock_irqrestore(&pas
->lock
, flags
);
545 EXPORT_SYMBOL(page_address
);
547 void set_page_address(struct page
*page
, void *virtual)
550 struct page_address_slot
*pas
;
551 struct page_address_map
*pam
;
553 BUG_ON(!PageHighMem(page
));
555 pas
= page_slot(page
);
556 if (virtual) { /* Add */
557 BUG_ON(list_empty(&page_address_pool
));
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
);
566 pam
->virtual = virtual;
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
);
583 spin_unlock_irqrestore(&pas
->lock
, flags
);
589 static struct page_address_map page_address_maps
[LAST_PKMAP
];
591 void __init
page_address_init(void)
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
);
602 spin_lock_init(&pool_lock
);
605 #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */