SAFE public projects git trees. - safe/jmp/linux-2.6/blob - mm/highmem.c

   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                 if (pte_none(pkmap_page_table[i]))
  78                         BUG();
  79
  80                 /*
  81                  * Don't need an atomic fetch-and-clear op here;
  82                  * no-one has the page mapped, and cannot get at
  83                  * its virtual address (and hence PTE) without first
  84                  * getting the kmap_lock (which is held here).
  85                  * So no dangers, even with speculative execution.
  86                  */
  87                 page = pte_page(pkmap_page_table[i]);
  88                 pte_clear(&init_mm, (unsigned long)page_address(page),
  89                           &pkmap_page_table[i]);
  90
  91                 set_page_address(page, NULL);
  92         }
  93         flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
  94 }
  95
  96 static inline unsigned long map_new_virtual(struct page *page)
  97 {
  98         unsigned long vaddr;
  99         int count;
 100
 101 start:
 102         count = LAST_PKMAP;
 103         /* Find an empty entry */
 104         for (;;) {
 105                 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
 106                 if (!last_pkmap_nr) {
 107                         flush_all_zero_pkmaps();
 108                         count = LAST_PKMAP;
 109                 }
 110                 if (!pkmap_count[last_pkmap_nr])
 111                         break;  /* Found a usable entry */
 112                 if (--count)
 113                         continue;
 114
 115                 /*
 116                  * Sleep for somebody else to unmap their entries
 117                  */
 118                 {
 119                         DECLARE_WAITQUEUE(wait, current);
 120
 121                         __set_current_state(TASK_UNINTERRUPTIBLE);
 122                         add_wait_queue(&pkmap_map_wait, &wait);
 123                         spin_unlock(&kmap_lock);
 124                         schedule();
 125                         remove_wait_queue(&pkmap_map_wait, &wait);
 126                         spin_lock(&kmap_lock);
 127
 128                         /* Somebody else might have mapped it while we slept */
 129                         if (page_address(page))
 130                                 return (unsigned long)page_address(page);
 131
 132                         /* Re-start */
 133                         goto start;
 134                 }
 135         }
 136         vaddr = PKMAP_ADDR(last_pkmap_nr);
 137         set_pte_at(&init_mm, vaddr,
 138                    &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
 139
 140         pkmap_count[last_pkmap_nr] = 1;
 141         set_page_address(page, (void *)vaddr);
 142
 143         return vaddr;
 144 }
 145
 146 void fastcall *kmap_high(struct page *page)
 147 {
 148         unsigned long vaddr;
 149
 150         /*
 151          * For highmem pages, we can't trust "virtual" until
 152          * after we have the lock.
 153          *
 154          * We cannot call this from interrupts, as it may block
 155          */
 156         spin_lock(&kmap_lock);
 157         vaddr = (unsigned long)page_address(page);
 158         if (!vaddr)
 159                 vaddr = map_new_virtual(page);
 160         pkmap_count[PKMAP_NR(vaddr)]++;
 161         if (pkmap_count[PKMAP_NR(vaddr)] < 2)
 162                 BUG();
 163         spin_unlock(&kmap_lock);
 164         return (void*) vaddr;
 165 }
 166
 167 EXPORT_SYMBOL(kmap_high);
 168
 169 void fastcall kunmap_high(struct page *page)
 170 {
 171         unsigned long vaddr;
 172         unsigned long nr;
 173         int need_wakeup;
 174
 175         spin_lock(&kmap_lock);
 176         vaddr = (unsigned long)page_address(page);
 177         if (!vaddr)
 178                 BUG();
 179         nr = PKMAP_NR(vaddr);
 180
 181         /*
 182          * A count must never go down to zero
 183          * without a TLB flush!
 184          */
 185         need_wakeup = 0;
 186         switch (--pkmap_count[nr]) {
 187         case 0:
 188                 BUG();
 189         case 1:
 190                 /*
 191                  * Avoid an unnecessary wake_up() function call.
 192                  * The common case is pkmap_count[] == 1, but
 193                  * no waiters.
 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.
 199                  */
 200                 need_wakeup = waitqueue_active(&pkmap_map_wait);
 201         }
 202         spin_unlock(&kmap_lock);
 203
 204         /* do wake-up, if needed, race-free outside of the spin lock */
 205         if (need_wakeup)
 206                 wake_up(&pkmap_map_wait);
 207 }
 208
 209 EXPORT_SYMBOL(kunmap_high);
 210
 211 #define POOL_SIZE       64
 212
 213 static __init int init_emergency_pool(void)
 214 {
 215         struct sysinfo i;
 216         si_meminfo(&i);
 217         si_swapinfo(&i);
 218
 219         if (!i.totalhigh)
 220                 return 0;
 221
 222         page_pool = mempool_create_page_pool(POOL_SIZE, 0);
 223         if (!page_pool)
 224                 BUG();
 225         printk("highmem bounce pool size: %d pages\n", POOL_SIZE);
 226
 227         return 0;
 228 }
 229
 230 __initcall(init_emergency_pool);
 231
 232 /*
 233  * highmem version, map in to vec
 234  */
 235 static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
 236 {
 237         unsigned long flags;
 238         unsigned char *vto;
 239
 240         local_irq_save(flags);
 241         vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ);
 242         memcpy(vto + to->bv_offset, vfrom, to->bv_len);
 243         kunmap_atomic(vto, KM_BOUNCE_READ);
 244         local_irq_restore(flags);
 245 }
 246
 247 #else /* CONFIG_HIGHMEM */
 248
 249 #define bounce_copy_vec(to, vfrom)      \
 250         memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
 251
 252 #endif
 253
 254 #define ISA_POOL_SIZE   16
 255
 256 /*
 257  * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
 258  * as the max address, so check if the pool has already been created.
 259  */
 260 int init_emergency_isa_pool(void)
 261 {
 262         if (isa_page_pool)
 263                 return 0;
 264
 265         isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
 266                                        mempool_free_pages, (void *) 0);
 267         if (!isa_page_pool)
 268                 BUG();
 269
 270         printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE);
 271         return 0;
 272 }
 273
 274 /*
 275  * Simple bounce buffer support for highmem pages. Depending on the
 276  * queue gfp mask set, *to may or may not be a highmem page. kmap it
 277  * always, it will do the Right Thing
 278  */
 279 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
 280 {
 281         unsigned char *vfrom;
 282         struct bio_vec *tovec, *fromvec;
 283         int i;
 284
 285         __bio_for_each_segment(tovec, to, i, 0) {
 286                 fromvec = from->bi_io_vec + i;
 287
 288                 /*
 289                  * not bounced
 290                  */
 291                 if (tovec->bv_page == fromvec->bv_page)
 292                         continue;
 293
 294                 /*
 295                  * fromvec->bv_offset and fromvec->bv_len might have been
 296                  * modified by the block layer, so use the original copy,
 297                  * bounce_copy_vec already uses tovec->bv_len
 298                  */
 299                 vfrom = page_address(fromvec->bv_page) + tovec->bv_offset;
 300
 301                 flush_dcache_page(tovec->bv_page);
 302                 bounce_copy_vec(tovec, vfrom);
 303         }
 304 }
 305
 306 static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
 307 {
 308         struct bio *bio_orig = bio->bi_private;
 309         struct bio_vec *bvec, *org_vec;
 310         int i;
 311
 312         if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
 313                 set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
 314
 315         /*
 316          * free up bounce indirect pages used
 317          */
 318         __bio_for_each_segment(bvec, bio, i, 0) {
 319                 org_vec = bio_orig->bi_io_vec + i;
 320                 if (bvec->bv_page == org_vec->bv_page)
 321                         continue;
 322
 323                 mempool_free(bvec->bv_page, pool);
 324                 dec_page_state(nr_bounce);
 325         }
 326
 327         bio_endio(bio_orig, bio_orig->bi_size, err);
 328         bio_put(bio);
 329 }
 330
 331 static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done, int err)
 332 {
 333         if (bio->bi_size)
 334                 return 1;
 335
 336         bounce_end_io(bio, page_pool, err);
 337         return 0;
 338 }
 339
 340 static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err)
 341 {
 342         if (bio->bi_size)
 343                 return 1;
 344
 345         bounce_end_io(bio, isa_page_pool, err);
 346         return 0;
 347 }
 348
 349 static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
 350 {
 351         struct bio *bio_orig = bio->bi_private;
 352
 353         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
 354                 copy_to_high_bio_irq(bio_orig, bio);
 355
 356         bounce_end_io(bio, pool, err);
 357 }
 358
 359 static int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
 360 {
 361         if (bio->bi_size)
 362                 return 1;
 363
 364         __bounce_end_io_read(bio, page_pool, err);
 365         return 0;
 366 }
 367
 368 static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err)
 369 {
 370         if (bio->bi_size)
 371                 return 1;
 372
 373         __bounce_end_io_read(bio, isa_page_pool, err);
 374         return 0;
 375 }
 376
 377 static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig,
 378                                mempool_t *pool)
 379 {
 380         struct page *page;
 381         struct bio *bio = NULL;
 382         int i, rw = bio_data_dir(*bio_orig);
 383         struct bio_vec *to, *from;
 384
 385         bio_for_each_segment(from, *bio_orig, i) {
 386                 page = from->bv_page;
 387
 388                 /*
 389                  * is destination page below bounce pfn?
 390                  */
 391                 if (page_to_pfn(page) < q->bounce_pfn)
 392                         continue;
 393
 394                 /*
 395                  * irk, bounce it
 396                  */
 397                 if (!bio)
 398                         bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
 399
 400                 to = bio->bi_io_vec + i;
 401
 402                 to->bv_page = mempool_alloc(pool, q->bounce_gfp);
 403                 to->bv_len = from->bv_len;
 404                 to->bv_offset = from->bv_offset;
 405                 inc_page_state(nr_bounce);
 406
 407                 if (rw == WRITE) {
 408                         char *vto, *vfrom;
 409
 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);
 415                 }
 416         }
 417
 418         /*
 419          * no pages bounced
 420          */
 421         if (!bio)
 422                 return;
 423
 424         /*
 425          * at least one page was bounced, fill in possible non-highmem
 426          * pages
 427          */
 428         __bio_for_each_segment(from, *bio_orig, i, 0) {
 429                 to = bio_iovec_idx(bio, i);
 430                 if (!to->bv_page) {
 431                         to->bv_page = from->bv_page;
 432                         to->bv_len = from->bv_len;
 433                         to->bv_offset = from->bv_offset;
 434                 }
 435         }
 436
 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;
 441
 442         bio->bi_vcnt = (*bio_orig)->bi_vcnt;
 443         bio->bi_idx = (*bio_orig)->bi_idx;
 444         bio->bi_size = (*bio_orig)->bi_size;
 445
 446         if (pool == page_pool) {
 447                 bio->bi_end_io = bounce_end_io_write;
 448                 if (rw == READ)
 449                         bio->bi_end_io = bounce_end_io_read;
 450         } else {
 451                 bio->bi_end_io = bounce_end_io_write_isa;
 452                 if (rw == READ)
 453                         bio->bi_end_io = bounce_end_io_read_isa;
 454         }
 455
 456         bio->bi_private = *bio_orig;
 457         *bio_orig = bio;
 458 }
 459
 460 void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig)
 461 {
 462         mempool_t *pool;
 463
 464         /*
 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
 468          */
 469         if (!(q->bounce_gfp & GFP_DMA)) {
 470                 if (q->bounce_pfn >= blk_max_pfn)
 471                         return;
 472                 pool = page_pool;
 473         } else {
 474                 BUG_ON(!isa_page_pool);
 475                 pool = isa_page_pool;
 476         }
 477
 478         blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE);
 479
 480         /*
 481          * slow path
 482          */
 483         __blk_queue_bounce(q, bio_orig, pool);
 484 }
 485
 486 EXPORT_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  */
 495 struct 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  */
 504 static struct list_head page_address_pool;      /* freelist */
 505 static spinlock_t pool_lock;                    /* protects page_address_pool */
 506
 507 /*
 508  * Hash table bucket
 509  */
 510 static 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
 515 static struct page_address_slot *page_slot(struct page *page)
 516 {
 517         return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
 518 }
 519
 520 void *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         }
 542 done:
 543         spin_unlock_irqrestore(&pas->lock, flags);
 544         return ret;
 545 }
 546
 547 EXPORT_SYMBOL(page_address);
 548
 549 void 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         }
 587 done:
 588         return;
 589 }
 590
 591 static struct page_address_map page_address_maps[LAST_PKMAP];
 592
 593 void __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) */