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/swap.h>
21 #include <linux/bio.h>
22 #include <linux/pagemap.h>
23 #include <linux/mempool.h>
24 #include <linux/blkdev.h>
25 #include <linux/init.h>
26 #include <linux/hash.h>
27 #include <asm/pgalloc.h>
28 #include <asm/tlbflush.h>
30 static mempool_t
*page_pool
, *isa_page_pool
;
32 static void *page_pool_alloc(int gfp_mask
, void *data
)
34 int gfp
= gfp_mask
| (int) (long) data
;
36 return alloc_page(gfp
);
39 static void page_pool_free(void *page
, void *data
)
45 * Virtual_count is not a pure "count".
46 * 0 means that it is not mapped, and has not been mapped
47 * since a TLB flush - it is usable.
48 * 1 means that there are no users, but it has been mapped
49 * since the last TLB flush - so we can't use it.
50 * n means that there are (n-1) current users of it.
53 static int pkmap_count
[LAST_PKMAP
];
54 static unsigned int last_pkmap_nr
;
55 static spinlock_t kmap_lock __cacheline_aligned_in_smp
= SPIN_LOCK_UNLOCKED
;
57 pte_t
* pkmap_page_table
;
59 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait
);
61 static void flush_all_zero_pkmaps(void)
67 for (i
= 0; i
< LAST_PKMAP
; i
++) {
71 * zero means we don't have anything to do,
72 * >1 means that it is still in use. Only
73 * a count of 1 means that it is free but
74 * needs to be unmapped
76 if (pkmap_count
[i
] != 1)
81 if (pte_none(pkmap_page_table
[i
]))
85 * Don't need an atomic fetch-and-clear op here;
86 * no-one has the page mapped, and cannot get at
87 * its virtual address (and hence PTE) without first
88 * getting the kmap_lock (which is held here).
89 * So no dangers, even with speculative execution.
91 page
= pte_page(pkmap_page_table
[i
]);
92 pte_clear(&pkmap_page_table
[i
]);
94 set_page_address(page
, NULL
);
96 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP
));
99 static inline unsigned long map_new_virtual(struct page
*page
)
106 /* Find an empty entry */
108 last_pkmap_nr
= (last_pkmap_nr
+ 1) & LAST_PKMAP_MASK
;
109 if (!last_pkmap_nr
) {
110 flush_all_zero_pkmaps();
113 if (!pkmap_count
[last_pkmap_nr
])
114 break; /* Found a usable entry */
119 * Sleep for somebody else to unmap their entries
122 DECLARE_WAITQUEUE(wait
, current
);
124 __set_current_state(TASK_UNINTERRUPTIBLE
);
125 add_wait_queue(&pkmap_map_wait
, &wait
);
126 spin_unlock(&kmap_lock
);
128 remove_wait_queue(&pkmap_map_wait
, &wait
);
129 spin_lock(&kmap_lock
);
131 /* Somebody else might have mapped it while we slept */
132 if (page_address(page
))
133 return (unsigned long)page_address(page
);
139 vaddr
= PKMAP_ADDR(last_pkmap_nr
);
140 set_pte(&(pkmap_page_table
[last_pkmap_nr
]), mk_pte(page
, kmap_prot
));
142 pkmap_count
[last_pkmap_nr
] = 1;
143 set_page_address(page
, (void *)vaddr
);
148 void *kmap_high(struct page
*page
)
153 * For highmem pages, we can't trust "virtual" until
154 * after we have the lock.
156 * We cannot call this from interrupts, as it may block
158 spin_lock(&kmap_lock
);
159 vaddr
= (unsigned long)page_address(page
);
161 vaddr
= map_new_virtual(page
);
162 pkmap_count
[PKMAP_NR(vaddr
)]++;
163 if (pkmap_count
[PKMAP_NR(vaddr
)] < 2)
165 spin_unlock(&kmap_lock
);
166 return (void*) vaddr
;
169 void kunmap_high(struct page
*page
)
175 spin_lock(&kmap_lock
);
176 vaddr
= (unsigned long)page_address(page
);
179 nr
= PKMAP_NR(vaddr
);
182 * A count must never go down to zero
183 * without a TLB flush!
186 switch (--pkmap_count
[nr
]) {
191 * Avoid an unnecessary wake_up() function call.
192 * The common case is pkmap_count[] == 1, but
194 * The tasks queued in the wait-queue are guarded
195 * by both the lock in the wait-queue-head and by
196 * the kmap_lock. As the kmap_lock is held here,
197 * no need for the wait-queue-head's lock. Simply
198 * test if the queue is empty.
200 need_wakeup
= waitqueue_active(&pkmap_map_wait
);
202 spin_unlock(&kmap_lock
);
204 /* do wake-up, if needed, race-free outside of the spin lock */
206 wake_up(&pkmap_map_wait
);
211 static __init
int init_emergency_pool(void)
220 page_pool
= mempool_create(POOL_SIZE
, page_pool_alloc
, page_pool_free
, NULL
);
223 printk("highmem bounce pool size: %d pages\n", POOL_SIZE
);
228 __initcall(init_emergency_pool
);
231 * highmem version, map in to vec
233 static void bounce_copy_vec(struct bio_vec
*to
, unsigned char *vfrom
)
238 local_irq_save(flags
);
239 vto
= kmap_atomic(to
->bv_page
, KM_BOUNCE_READ
);
240 memcpy(vto
+ to
->bv_offset
, vfrom
, to
->bv_len
);
241 kunmap_atomic(vto
, KM_BOUNCE_READ
);
242 local_irq_restore(flags
);
245 #else /* CONFIG_HIGHMEM */
247 #define bounce_copy_vec(to, vfrom) \
248 memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
252 #define ISA_POOL_SIZE 16
255 * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
256 * as the max address, so check if the pool has already been created.
258 int init_emergency_isa_pool(void)
263 isa_page_pool
= mempool_create(ISA_POOL_SIZE
, page_pool_alloc
, page_pool_free
, (void *) __GFP_DMA
);
267 printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE
);
272 * Simple bounce buffer support for highmem pages. Depending on the
273 * queue gfp mask set, *to may or may not be a highmem page. kmap it
274 * always, it will do the Right Thing
276 static void copy_to_high_bio_irq(struct bio
*to
, struct bio
*from
)
278 unsigned char *vfrom
;
279 struct bio_vec
*tovec
, *fromvec
;
282 __bio_for_each_segment(tovec
, to
, i
, 0) {
283 fromvec
= from
->bi_io_vec
+ i
;
288 if (tovec
->bv_page
== fromvec
->bv_page
)
291 vfrom
= page_address(fromvec
->bv_page
) + fromvec
->bv_offset
;
293 bounce_copy_vec(tovec
, vfrom
);
297 static void bounce_end_io(struct bio
*bio
, mempool_t
*pool
)
299 struct bio
*bio_orig
= bio
->bi_private
;
300 struct bio_vec
*bvec
, *org_vec
;
303 if (!test_bit(BIO_UPTODATE
, &bio
->bi_flags
))
306 set_bit(BIO_UPTODATE
, &bio_orig
->bi_flags
);
309 * free up bounce indirect pages used
311 __bio_for_each_segment(bvec
, bio
, i
, 0) {
312 org_vec
= bio_orig
->bi_io_vec
+ i
;
313 if (bvec
->bv_page
== org_vec
->bv_page
)
316 mempool_free(bvec
->bv_page
, pool
);
320 bio_endio(bio_orig
, bio_orig
->bi_size
, 0);
324 static int bounce_end_io_write(struct bio
*bio
, unsigned int bytes_done
,int err
)
329 bounce_end_io(bio
, page_pool
);
333 static int bounce_end_io_write_isa(struct bio
*bio
, unsigned int bytes_done
, int err
)
338 bounce_end_io(bio
, isa_page_pool
);
342 static void __bounce_end_io_read(struct bio
*bio
, mempool_t
*pool
)
344 struct bio
*bio_orig
= bio
->bi_private
;
346 if (test_bit(BIO_UPTODATE
, &bio
->bi_flags
))
347 copy_to_high_bio_irq(bio_orig
, bio
);
349 bounce_end_io(bio
, pool
);
352 static int bounce_end_io_read(struct bio
*bio
, unsigned int bytes_done
, int err
)
357 __bounce_end_io_read(bio
, page_pool
);
361 static int bounce_end_io_read_isa(struct bio
*bio
, unsigned int bytes_done
, int err
)
366 __bounce_end_io_read(bio
, isa_page_pool
);
370 static void __blk_queue_bounce(request_queue_t
*q
, struct bio
**bio_orig
,
374 struct bio
*bio
= NULL
;
375 int i
, rw
= bio_data_dir(*bio_orig
);
376 struct bio_vec
*to
, *from
;
378 bio_for_each_segment(from
, *bio_orig
, i
) {
379 page
= from
->bv_page
;
382 * is destination page below bounce pfn?
384 if (page_to_pfn(page
) < q
->bounce_pfn
)
391 bio
= bio_alloc(GFP_NOIO
, (*bio_orig
)->bi_vcnt
);
393 to
= bio
->bi_io_vec
+ i
;
395 to
->bv_page
= mempool_alloc(pool
, q
->bounce_gfp
);
396 to
->bv_len
= from
->bv_len
;
397 to
->bv_offset
= from
->bv_offset
;
402 vto
= page_address(to
->bv_page
) + to
->bv_offset
;
403 vfrom
= kmap(from
->bv_page
) + from
->bv_offset
;
404 memcpy(vto
, vfrom
, to
->bv_len
);
405 kunmap(from
->bv_page
);
416 * at least one page was bounced, fill in possible non-highmem
419 bio_for_each_segment(from
, *bio_orig
, i
) {
420 to
= bio_iovec_idx(bio
, i
);
422 to
->bv_page
= from
->bv_page
;
423 to
->bv_len
= from
->bv_len
;
424 to
->bv_offset
= from
->bv_offset
;
428 bio
->bi_bdev
= (*bio_orig
)->bi_bdev
;
429 bio
->bi_flags
|= (1 << BIO_BOUNCED
);
430 bio
->bi_sector
= (*bio_orig
)->bi_sector
;
431 bio
->bi_rw
= (*bio_orig
)->bi_rw
;
433 bio
->bi_vcnt
= (*bio_orig
)->bi_vcnt
;
435 bio
->bi_size
= (*bio_orig
)->bi_size
;
437 if (pool
== page_pool
) {
438 bio
->bi_end_io
= bounce_end_io_write
;
440 bio
->bi_end_io
= bounce_end_io_read
;
442 bio
->bi_end_io
= bounce_end_io_write_isa
;
444 bio
->bi_end_io
= bounce_end_io_read_isa
;
447 bio
->bi_private
= *bio_orig
;
451 void blk_queue_bounce(request_queue_t
*q
, struct bio
**bio_orig
)
456 * for non-isa bounce case, just check if the bounce pfn is equal
457 * to or bigger than the highest pfn in the system -- in that case,
458 * don't waste time iterating over bio segments
460 if (!(q
->bounce_gfp
& GFP_DMA
)) {
461 if (q
->bounce_pfn
>= blk_max_pfn
)
465 BUG_ON(!isa_page_pool
);
466 pool
= isa_page_pool
;
472 __blk_queue_bounce(q
, bio_orig
, pool
);
475 #if defined(HASHED_PAGE_VIRTUAL)
477 #define PA_HASH_ORDER 7
480 * Describes one page->virtual association
482 struct page_address_map
{
485 struct list_head list
;
489 * page_address_map freelist, allocated from page_address_maps.
491 static struct list_head page_address_pool
; /* freelist */
492 static spinlock_t pool_lock
; /* protects page_address_pool */
497 static struct page_address_slot
{
498 struct list_head lh
; /* List of page_address_maps */
499 spinlock_t lock
; /* Protect this bucket's list */
500 } ____cacheline_aligned_in_smp page_address_htable
[1<<PA_HASH_ORDER
];
502 static struct page_address_slot
*page_slot(struct page
*page
)
504 return &page_address_htable
[hash_ptr(page
, PA_HASH_ORDER
)];
507 void *page_address(struct page
*page
)
511 struct page_address_slot
*pas
;
513 if (!PageHighMem(page
))
514 return lowmem_page_address(page
);
516 pas
= page_slot(page
);
518 spin_lock_irqsave(&pas
->lock
, flags
);
519 if (!list_empty(&pas
->lh
)) {
520 struct page_address_map
*pam
;
522 list_for_each_entry(pam
, &pas
->lh
, list
) {
523 if (pam
->page
== page
) {
530 spin_unlock_irqrestore(&pas
->lock
, flags
);
534 void set_page_address(struct page
*page
, void *virtual)
537 struct page_address_slot
*pas
;
538 struct page_address_map
*pam
;
540 BUG_ON(!PageHighMem(page
));
542 pas
= page_slot(page
);
543 if (virtual) { /* Add */
544 BUG_ON(list_empty(&page_address_pool
));
546 spin_lock_irqsave(&pool_lock
, flags
);
547 pam
= list_entry(page_address_pool
.next
,
548 struct page_address_map
, list
);
549 list_del(&pam
->list
);
550 spin_unlock_irqrestore(&pool_lock
, flags
);
553 pam
->virtual = virtual;
555 spin_lock_irqsave(&pas
->lock
, flags
);
556 list_add_tail(&pam
->list
, &pas
->lh
);
557 spin_unlock_irqrestore(&pas
->lock
, flags
);
558 } else { /* Remove */
559 spin_lock_irqsave(&pas
->lock
, flags
);
560 list_for_each_entry(pam
, &pas
->lh
, list
) {
561 if (pam
->page
== page
) {
562 list_del(&pam
->list
);
563 spin_unlock_irqrestore(&pas
->lock
, flags
);
564 spin_lock_irqsave(&pool_lock
, flags
);
565 list_add_tail(&pam
->list
, &page_address_pool
);
566 spin_unlock_irqrestore(&pool_lock
, flags
);
570 spin_unlock_irqrestore(&pas
->lock
, flags
);
576 static struct page_address_map page_address_maps
[LAST_PKMAP
];
578 void __init
page_address_init(void)
582 INIT_LIST_HEAD(&page_address_pool
);
583 for (i
= 0; i
< ARRAY_SIZE(page_address_maps
); i
++)
584 list_add(&page_address_maps
[i
].list
, &page_address_pool
);
585 for (i
= 0; i
< ARRAY_SIZE(page_address_htable
); i
++) {
586 INIT_LIST_HEAD(&page_address_htable
[i
].lh
);
587 spin_lock_init(&page_address_htable
[i
].lock
);
589 spin_lock_init(&pool_lock
);
592 #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */