1 files changed, 607 insertions, 0 deletions

diff --git a/mm/highmem.c b/mm/highmem.c
new file mode 100644
index 000000000000..d01276506b00
--- /dev/null
+++ b/mm/highmem.c
@@ -0,0 +1,607 @@
+/*
+ * 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);      
+        }
+
+        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;
+
+                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) */