/* * High memory handling common code and variables. * * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de * Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de * * * Redesigned the x86 32-bit VM architecture to deal with * 64-bit physical space. With current x86 CPUs this * means up to 64 Gigabytes physical RAM. * * Rewrote high memory support to move the page cache into * high memory. Implemented permanent (schedulable) kmaps * based on Linus' idea. * * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> */ #include <linux/mm.h> #include <linux/module.h> #include <linux/swap.h> #include <linux/bio.h> #include <linux/pagemap.h> #include <linux/mempool.h> #include <linux/blkdev.h> #include <linux/init.h> #include <linux/hash.h> #include <linux/highmem.h> #include <asm/tlbflush.h> static mempool_t *page_pool, *isa_page_pool; static void *page_pool_alloc(unsigned int __nocast gfp_mask, void *data) { unsigned int gfp = gfp_mask | (unsigned int) (long) data; return alloc_page(gfp); } static void page_pool_free(void *page, void *data) { __free_page(page); } /* * Virtual_count is not a pure "count". * 0 means that it is not mapped, and has not been mapped * since a TLB flush - it is usable. * 1 means that there are no users, but it has been mapped * since the last TLB flush - so we can't use it. * n means that there are (n-1) current users of it. */ #ifdef CONFIG_HIGHMEM static int pkmap_count[LAST_PKMAP]; static unsigned int last_pkmap_nr; static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); pte_t * pkmap_page_table; static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); static void flush_all_zero_pkmaps(void) { int i; flush_cache_kmaps(); for (i = 0; i < LAST_PKMAP; i++) { struct page *page; /* * zero means we don't have anything to do, * >1 means that it is still in use. Only * a count of 1 means that it is free but * needs to be unmapped */ if (pkmap_count[i] != 1) continue; pkmap_count[i] = 0; /* sanity check */ if (pte_none(pkmap_page_table[i])) BUG(); /* * Don't need an atomic fetch-and-clear op here; * no-one has the page mapped, and cannot get at * its virtual address (and hence PTE) without first * getting the kmap_lock (which is held here). * So no dangers, even with speculative execution. */ page = pte_page(pkmap_page_table[i]); pte_clear(&init_mm, (unsigned long)page_address(page), &pkmap_page_table[i]); set_page_address(page, NULL); } flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP)); } static inline unsigned long map_new_virtual(struct page *page) { unsigned long vaddr; int count; start: count = LAST_PKMAP; /* Find an empty entry */ for (;;) { last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK; if (!last_pkmap_nr) { flush_all_zero_pkmaps(); count = LAST_PKMAP; } if (!pkmap_count[last_pkmap_nr]) break; /* Found a usable entry */ if (--count) continue; /* * Sleep for somebody else to unmap their entries */ { DECLARE_WAITQUEUE(wait, current); __set_current_state(TASK_UNINTERRUPTIBLE); add_wait_queue(&pkmap_map_wait, &wait); spin_unlock(&kmap_lock); schedule(); remove_wait_queue(&pkmap_map_wait, &wait); spin_lock(&kmap_lock); /* Somebody else might have mapped it while we slept */ if (page_address(page)) return (unsigned long)page_address(page); /* Re-start */ goto start; } } vaddr = PKMAP_ADDR(last_pkmap_nr); set_pte_at(&init_mm, vaddr, &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot)); pkmap_count[last_pkmap_nr] = 1; set_page_address(page, (void *)vaddr); return vaddr; } void fastcall *kmap_high(struct page *page) { unsigned long vaddr; /* * For highmem pages, we can't trust "virtual" until * after we have the lock. * * We cannot call this from interrupts, as it may block */ spin_lock(&kmap_lock); vaddr = (unsigned long)page_address(page); if (!vaddr) vaddr = map_new_virtual(page); pkmap_count[PKMAP_NR(vaddr)]++; if (pkmap_count[PKMAP_NR(vaddr)] < 2) BUG(); spin_unlock(&kmap_lock); return (void*) vaddr; } EXPORT_SYMBOL(kmap_high); void fastcall kunmap_high(struct page *page) { unsigned long vaddr; unsigned long nr; int need_wakeup; spin_lock(&kmap_lock); vaddr = (unsigned long)page_address(page); if (!vaddr) BUG(); nr = PKMAP_NR(vaddr); /* * A count must never go down to zero * without a TLB flush! */ need_wakeup = 0; switch (--pkmap_count[nr]) { case 0: BUG(); case 1: /* * Avoid an unnecessary wake_up() function call. * The common case is pkmap_count[] == 1, but * no waiters. * The tasks queued in the wait-queue are guarded * by both the lock in the wait-queue-head and by * the kmap_lock. As the kmap_lock is held here, * no need for the wait-queue-head's lock. Simply * test if the queue is empty. */ need_wakeup = waitqueue_active(&pkmap_map_wait); } spin_unlock(&kmap_lock); /* do wake-up, if needed, race-free outside of the spin lock */ if (need_wakeup) wake_up(&pkmap_map_wait); } EXPORT_SYMBOL(kunmap_high); #define POOL_SIZE 64 static __init int init_emergency_pool(void) { struct sysinfo i; si_meminfo(&i); si_swapinfo(&i); if (!i.totalhigh) return 0; page_pool = mempool_create(POOL_SIZE, page_pool_alloc, page_pool_free, NULL); if (!page_pool) BUG(); printk("highmem bounce pool size: %d pages\n", POOL_SIZE); return 0; } __initcall(init_emergency_pool); /* * highmem version, map in to vec */ static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) { unsigned long flags; unsigned char *vto; local_irq_save(flags); vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ); memcpy(vto + to->bv_offset, vfrom, to->bv_len); kunmap_atomic(vto, KM_BOUNCE_READ); local_irq_restore(flags); } #else /* CONFIG_HIGHMEM */ #define bounce_copy_vec(to, vfrom) \ memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) #endif #define ISA_POOL_SIZE 16 /* * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA * as the max address, so check if the pool has already been created. */ int init_emergency_isa_pool(void) { if (isa_page_pool) return 0; isa_page_pool = mempool_create(ISA_POOL_SIZE, page_pool_alloc, page_pool_free, (void *) __GFP_DMA); if (!isa_page_pool) BUG(); printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE); return 0; } /* * Simple bounce buffer support for highmem pages. Depending on the * queue gfp mask set, *to may or may not be a highmem page. kmap it * always, it will do the Right Thing */ static void copy_to_high_bio_irq(struct bio *to, struct bio *from) { unsigned char *vfrom; struct bio_vec *tovec, *fromvec; int i; __bio_for_each_segment(tovec, to, i, 0) { fromvec = from->bi_io_vec + i; /* * not bounced */ if (tovec->bv_page == fromvec->bv_page) continue; /* * fromvec->bv_offset and fromvec->bv_len might have been * modified by the block layer, so use the original copy, * bounce_copy_vec already uses tovec->bv_len */ vfrom = page_address(fromvec->bv_page) + tovec->bv_offset; flush_dcache_page(tovec->bv_page); bounce_copy_vec(tovec, vfrom); } } static void bounce_end_io(struct bio *bio, mempool_t *pool, int err) { struct bio *bio_orig = bio->bi_private; struct bio_vec *bvec, *org_vec; int i; if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags)) set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags); /* * free up bounce indirect pages used */ __bio_for_each_segment(bvec, bio, i, 0) { org_vec = bio_orig->bi_io_vec + i; if (bvec->bv_page == org_vec->bv_page) continue; mempool_free(bvec->bv_page, pool); dec_page_state(nr_bounce); } bio_endio(bio_orig, bio_orig->bi_size, err); bio_put(bio); } static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done,int err) { if (bio->bi_size) return 1; bounce_end_io(bio, page_pool, err); return 0; } static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err) { if (bio->bi_size) return 1; bounce_end_io(bio, isa_page_pool, err); return 0; } static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err) { struct bio *bio_orig = bio->bi_private; if (test_bit(BIO_UPTODATE, &bio->bi_flags)) copy_to_high_bio_irq(bio_orig, bio); bounce_end_io(bio, pool, err); } static int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err) { if (bio->bi_size) return 1; __bounce_end_io_read(bio, page_pool, err); return 0; } static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err) { if (bio->bi_size) return 1; __bounce_end_io_read(bio, isa_page_pool, err); return 0; } static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig, mempool_t *pool) { struct page *page; struct bio *bio = NULL; int i, rw = bio_data_dir(*bio_orig); struct bio_vec *to, *from; bio_for_each_segment(from, *bio_orig, i) { page = from->bv_page; /* * is destination page below bounce pfn? */ if (page_to_pfn(page) < q->bounce_pfn) continue; /* * irk, bounce it */ if (!bio) bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt); to = bio->bi_io_vec + i; to->bv_page = mempool_alloc(pool, q->bounce_gfp); to->bv_len = from->bv_len; to->bv_offset = from->bv_offset; inc_page_state(nr_bounce); if (rw == WRITE) { char *vto, *vfrom; flush_dcache_page(from->bv_page); vto = page_address(to->bv_page) + to->bv_offset; vfrom = kmap(from->bv_page) + from->bv_offset; memcpy(vto, vfrom, to->bv_len); kunmap(from->bv_page); } } /* * no pages bounced */ if (!bio) return; /* * at least one page was bounced, fill in possible non-highmem * pages */ __bio_for_each_segment(from, *bio_orig, i, 0) { to = bio_iovec_idx(bio, i); if (!to->bv_page) { to->bv_page = from->bv_page; to->bv_len = from->bv_len; to->bv_offset = from->bv_offset; } } bio->bi_bdev = (*bio_orig)->bi_bdev; bio->bi_flags |= (1 << BIO_BOUNCED); bio->bi_sector = (*bio_orig)->bi_sector; bio->bi_rw = (*bio_orig)->bi_rw; bio->bi_vcnt = (*bio_orig)->bi_vcnt; bio->bi_idx = (*bio_orig)->bi_idx; bio->bi_size = (*bio_orig)->bi_size; if (pool == page_pool) { bio->bi_end_io = bounce_end_io_write; if (rw == READ) bio->bi_end_io = bounce_end_io_read; } else { bio->bi_end_io = bounce_end_io_write_isa; if (rw == READ) bio->bi_end_io = bounce_end_io_read_isa; } bio->bi_private = *bio_orig; *bio_orig = bio; } void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig) { mempool_t *pool; /* * for non-isa bounce case, just check if the bounce pfn is equal * to or bigger than the highest pfn in the system -- in that case, * don't waste time iterating over bio segments */ if (!(q->bounce_gfp & GFP_DMA)) { if (q->bounce_pfn >= blk_max_pfn) return; pool = page_pool; } else { BUG_ON(!isa_page_pool); pool = isa_page_pool; } /* * slow path */ __blk_queue_bounce(q, bio_orig, pool); } EXPORT_SYMBOL(blk_queue_bounce); #if defined(HASHED_PAGE_VIRTUAL) #define PA_HASH_ORDER 7 /* * Describes one page->virtual association */ struct page_address_map { struct page *page; void *virtual; struct list_head list; }; /* * page_address_map freelist, allocated from page_address_maps. */ static struct list_head page_address_pool; /* freelist */ static spinlock_t pool_lock; /* protects page_address_pool */ /* * Hash table bucket */ static struct page_address_slot { struct list_head lh; /* List of page_address_maps */ spinlock_t lock; /* Protect this bucket's list */ } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER]; static struct page_address_slot *page_slot(struct page *page) { return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)]; } void *page_address(struct page *page) { unsigned long flags; void *ret; struct page_address_slot *pas; if (!PageHighMem(page)) return lowmem_page_address(page); pas = page_slot(page); ret = NULL; spin_lock_irqsave(&pas->lock, flags); if (!list_empty(&pas->lh)) { struct page_address_map *pam; list_for_each_entry(pam, &pas->lh, list) { if (pam->page == page) { ret = pam->virtual; goto done; } } } done: spin_unlock_irqrestore(&pas->lock, flags); return ret; } EXPORT_SYMBOL(page_address); void set_page_address(struct page *page, void *virtual) { unsigned long flags; struct page_address_slot *pas; struct page_address_map *pam; BUG_ON(!PageHighMem(page)); pas = page_slot(page); if (virtual) { /* Add */ BUG_ON(list_empty(&page_address_pool)); spin_lock_irqsave(&pool_lock, flags); pam = list_entry(page_address_pool.next, struct page_address_map, list); list_del(&pam->list); spin_unlock_irqrestore(&pool_lock, flags); pam->page = page; pam->virtual = virtual; spin_lock_irqsave(&pas->lock, flags); list_add_tail(&pam->list, &pas->lh); spin_unlock_irqrestore(&pas->lock, flags); } else { /* Remove */ spin_lock_irqsave(&pas->lock, flags); list_for_each_entry(pam, &pas->lh, list) { if (pam->page == page) { list_del(&pam->list); spin_unlock_irqrestore(&pas->lock, flags); spin_lock_irqsave(&pool_lock, flags); list_add_tail(&pam->list, &page_address_pool); spin_unlock_irqrestore(&pool_lock, flags); goto done; } } spin_unlock_irqrestore(&pas->lock, flags); } done: return; } static struct page_address_map page_address_maps[LAST_PKMAP]; void __init page_address_init(void) { int i; INIT_LIST_HEAD(&page_address_pool); for (i = 0; i < ARRAY_SIZE(page_address_maps); i++) list_add(&page_address_maps[i].list, &page_address_pool); for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) { INIT_LIST_HEAD(&page_address_htable[i].lh); spin_lock_init(&page_address_htable[i].lock); } spin_lock_init(&pool_lock); } #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */