[linux.git] / mm / highmem.c

/*
 * High memory handling common code and variables.
 *
 * (C) 1999 Andrea Arcangeli, SuSE GmbH, [email protected]
 *          Gerhard Wichert, Siemens AG, [email protected]
 *
 *
 * 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 <[email protected]>
 */

#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 <linux/kgdb.h>
#include <asm/tlbflush.h>

/*
 * 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

unsigned long totalhigh_pages __read_mostly;
EXPORT_SYMBOL(totalhigh_pages);

unsigned int nr_free_highpages (void)
{
	pg_data_t *pgdat;
	unsigned int pages = 0;

	for_each_online_pgdat(pgdat) {
		pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
			NR_FREE_PAGES);
		if (zone_movable_is_highmem())
			pages += zone_page_state(
					&pgdat->node_zones[ZONE_MOVABLE],
					NR_FREE_PAGES);
	}

	return pages;
}

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);

/*
 * Most architectures have no use for kmap_high_get(), so let's abstract
 * the disabling of IRQ out of the locking in that case to save on a
 * potential useless overhead.
 */
#ifdef ARCH_NEEDS_KMAP_HIGH_GET
#define lock_kmap()             spin_lock_irq(&kmap_lock)
#define unlock_kmap()           spin_unlock_irq(&kmap_lock)
#define lock_kmap_any(flags)    spin_lock_irqsave(&kmap_lock, flags)
#define unlock_kmap_any(flags)  spin_unlock_irqrestore(&kmap_lock, flags)
#else
#define lock_kmap()             spin_lock(&kmap_lock)
#define unlock_kmap()           spin_unlock(&kmap_lock)
#define lock_kmap_any(flags)    \
		do { spin_lock(&kmap_lock); (void)(flags); } while (0)
#define unlock_kmap_any(flags)  \
		do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
#endif

static void flush_all_zero_pkmaps(void)
{
	int i;
	int need_flush = 0;

	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 */
		BUG_ON(pte_none(pkmap_page_table[i]));

		/*
		 * 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);
		need_flush = 1;
	}
	if (need_flush)
		flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
}

/**
 * kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings
 */
void kmap_flush_unused(void)
{
	lock_kmap();
	flush_all_zero_pkmaps();
	unlock_kmap();
}

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);
			unlock_kmap();
			schedule();
			remove_wait_queue(&pkmap_map_wait, &wait);
			lock_kmap();

			/* 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;
}

/**
 * kmap_high - map a highmem page into memory
 * @page: &struct page to map
 *
 * Returns the page's virtual memory address.
 *
 * We cannot call this from interrupts, as it may block.
 */
void *kmap_high(struct page *page)
{
	unsigned long vaddr;

	/*
	 * For highmem pages, we can't trust "virtual" until
	 * after we have the lock.
	 */
	lock_kmap();
	vaddr = (unsigned long)page_address(page);
	if (!vaddr)
		vaddr = map_new_virtual(page);
	pkmap_count[PKMAP_NR(vaddr)]++;
	BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
	unlock_kmap();
	return (void*) vaddr;
}

EXPORT_SYMBOL(kmap_high);

#ifdef ARCH_NEEDS_KMAP_HIGH_GET
/**
 * kmap_high_get - pin a highmem page into memory
 * @page: &struct page to pin
 *
 * Returns the page's current virtual memory address, or NULL if no mapping
 * exists.  If and only if a non null address is returned then a
 * matching call to kunmap_high() is necessary.
 *
 * This can be called from any context.
 */
void *kmap_high_get(struct page *page)
{
	unsigned long vaddr, flags;

	lock_kmap_any(flags);
	vaddr = (unsigned long)page_address(page);
	if (vaddr) {
		BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
		pkmap_count[PKMAP_NR(vaddr)]++;
	}
	unlock_kmap_any(flags);
	return (void*) vaddr;
}
#endif

/**
 * kunmap_high - map a highmem page into memory
 * @page: &struct page to unmap
 *
 * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
 * only from user context.
 */
void kunmap_high(struct page *page)
{
	unsigned long vaddr;
	unsigned long nr;
	unsigned long flags;
	int need_wakeup;

	lock_kmap_any(flags);
	vaddr = (unsigned long)page_address(page);
	BUG_ON(!vaddr);
	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);
	}
	unlock_kmap_any(flags);

	/* do wake-up, if needed, race-free outside of the spin lock */
	if (need_wakeup)
		wake_up(&pkmap_map_wait);
}

EXPORT_SYMBOL(kunmap_high);
#endif

#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)];
}

/**
 * page_address - get the mapped virtual address of a page
 * @page: &struct page to get the virtual address of
 *
 * Returns the page's virtual address.
 */
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);

/**
 * set_page_address - set a page's virtual address
 * @page: &struct page to set
 * @virtual: virtual address to use
 */
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) */

#ifdef CONFIG_DEBUG_HIGHMEM

void debug_kmap_atomic(enum km_type type)
{
	static int warn_count = 10;

	if (unlikely(warn_count < 0))
		return;

	if (unlikely(in_interrupt())) {
		if (in_nmi()) {
			if (type != KM_NMI && type != KM_NMI_PTE) {
				WARN_ON(1);
				warn_count--;
			}
		} else if (in_irq()) {
			if (type != KM_IRQ0 && type != KM_IRQ1 &&
			    type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
			    type != KM_BOUNCE_READ && type != KM_IRQ_PTE) {
				WARN_ON(1);
				warn_count--;
			}
		} else if (!irqs_disabled()) {	/* softirq */
			if (type != KM_IRQ0 && type != KM_IRQ1 &&
			    type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
			    type != KM_SKB_SUNRPC_DATA &&
			    type != KM_SKB_DATA_SOFTIRQ &&
			    type != KM_BOUNCE_READ) {
				WARN_ON(1);
				warn_count--;
			}
		}
	}

	if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
			type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ ||
			type == KM_IRQ_PTE || type == KM_NMI ||
			type == KM_NMI_PTE ) {
		if (!irqs_disabled()) {
			WARN_ON(1);
			warn_count--;
		}
	} else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
		if (irq_count() == 0 && !irqs_disabled()) {
			WARN_ON(1);
			warn_count--;
		}
	}
#ifdef CONFIG_KGDB_KDB
	if (unlikely(type == KM_KDB && atomic_read(&kgdb_active) == -1)) {
		WARN_ON(1);
		warn_count--;
	}
#endif /* CONFIG_KGDB_KDB */
}

#endif
Commit	Line	Data
1da177e4 LT	1	/*
	2	* High memory handling common code and variables.
	3	*
	4	* (C) 1999 Andrea Arcangeli, SuSE GmbH, [email protected]
	5	* Gerhard Wichert, Siemens AG, [email protected]
	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 <[email protected]>
	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>
eac79005	29	#include <linux/kgdb.h>
1da177e4 LT	30	#include <asm/tlbflush.h>
1da177e4 LT	31
1da177e4 LT	32	/*
	33	* Virtual_count is not a pure "count".
	34	* 0 means that it is not mapped, and has not been mapped
	35	* since a TLB flush - it is usable.
	36	* 1 means that there are no users, but it has been mapped
	37	* since the last TLB flush - so we can't use it.
	38	* n means that there are (n-1) current users of it.
	39	*/
	40	#ifdef CONFIG_HIGHMEM
260b2367	41
c1f60a5a	42	unsigned long totalhigh_pages __read_mostly;
db7a94d6	43	EXPORT_SYMBOL(totalhigh_pages);
c1f60a5a CL	44
	45	unsigned int nr_free_highpages (void)
	46	{
	47	pg_data_t *pgdat;
	48	unsigned int pages = 0;
	49
2a1e274a	50	for_each_online_pgdat(pgdat) {
d23ad423 CL	51	pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
d23ad423 CL	52	NR_FREE_PAGES);
2a1e274a MG	53	if (zone_movable_is_highmem())
	54	pages += zone_page_state(
	55	&pgdat->node_zones[ZONE_MOVABLE],
	56	NR_FREE_PAGES);
	57	}
c1f60a5a CL	58
	59	return pages;
	60	}
	61
1da177e4 LT	62	static int pkmap_count[LAST_PKMAP];
	63	static unsigned int last_pkmap_nr;
	64	static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
	65
	66	pte_t * pkmap_page_table;
	67
	68	static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
	69
3297e760 NP	70	/*
	71	* Most architectures have no use for kmap_high_get(), so let's abstract
	72	* the disabling of IRQ out of the locking in that case to save on a
	73	* potential useless overhead.
	74	*/
	75	#ifdef ARCH_NEEDS_KMAP_HIGH_GET
	76	#define lock_kmap() spin_lock_irq(&kmap_lock)
	77	#define unlock_kmap() spin_unlock_irq(&kmap_lock)
	78	#define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags)
	79	#define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags)
	80	#else
	81	#define lock_kmap() spin_lock(&kmap_lock)
	82	#define unlock_kmap() spin_unlock(&kmap_lock)
	83	#define lock_kmap_any(flags) \
	84	do { spin_lock(&kmap_lock); (void)(flags); } while (0)
	85	#define unlock_kmap_any(flags) \
	86	do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
	87	#endif
	88
1da177e4 LT	89	static void flush_all_zero_pkmaps(void)
	90	{
	91	int i;
5843d9a4	92	int need_flush = 0;
1da177e4 LT	93
	94	flush_cache_kmaps();
	95
	96	for (i = 0; i < LAST_PKMAP; i++) {
	97	struct page *page;
	98
	99	/*
	100	* zero means we don't have anything to do,
	101	* >1 means that it is still in use. Only
	102	* a count of 1 means that it is free but
	103	* needs to be unmapped
	104	*/
	105	if (pkmap_count[i] != 1)
	106	continue;
	107	pkmap_count[i] = 0;
	108
	109	/* sanity check */
75babcac	110	BUG_ON(pte_none(pkmap_page_table[i]));
1da177e4 LT	111
	112	/*
	113	* Don't need an atomic fetch-and-clear op here;
	114	* no-one has the page mapped, and cannot get at
	115	* its virtual address (and hence PTE) without first
	116	* getting the kmap_lock (which is held here).
	117	* So no dangers, even with speculative execution.
	118	*/
	119	page = pte_page(pkmap_page_table[i]);
	120	pte_clear(&init_mm, (unsigned long)page_address(page),
	121	&pkmap_page_table[i]);
	122
	123	set_page_address(page, NULL);
5843d9a4	124	need_flush = 1;
1da177e4	125	}
5843d9a4 NP	126	if (need_flush)
5843d9a4 NP	127	flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
1da177e4 LT	128	}
1da177e4 LT	129
77f6078a RD	130	/**
	131	* kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings
	132	*/
ce6234b5 JF	133	void kmap_flush_unused(void)
ce6234b5 JF	134	{
3297e760	135	lock_kmap();
ce6234b5	136	flush_all_zero_pkmaps();
3297e760	137	unlock_kmap();
ce6234b5 JF	138	}
ce6234b5 JF	139
1da177e4 LT	140	static inline unsigned long map_new_virtual(struct page *page)
	141	{
	142	unsigned long vaddr;
	143	int count;
	144
	145	start:
	146	count = LAST_PKMAP;
	147	/* Find an empty entry */
	148	for (;;) {
	149	last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
	150	if (!last_pkmap_nr) {
	151	flush_all_zero_pkmaps();
	152	count = LAST_PKMAP;
	153	}
	154	if (!pkmap_count[last_pkmap_nr])
	155	break; /* Found a usable entry */
	156	if (--count)
	157	continue;
	158
	159	/*
	160	* Sleep for somebody else to unmap their entries
	161	*/
	162	{
	163	DECLARE_WAITQUEUE(wait, current);
	164
	165	__set_current_state(TASK_UNINTERRUPTIBLE);
	166	add_wait_queue(&pkmap_map_wait, &wait);
3297e760	167	unlock_kmap();
1da177e4 LT	168	schedule();
1da177e4 LT	169	remove_wait_queue(&pkmap_map_wait, &wait);
3297e760	170	lock_kmap();
1da177e4 LT	171
	172	/* Somebody else might have mapped it while we slept */
	173	if (page_address(page))
	174	return (unsigned long)page_address(page);
	175
	176	/* Re-start */
	177	goto start;
	178	}
	179	}
	180	vaddr = PKMAP_ADDR(last_pkmap_nr);
	181	set_pte_at(&init_mm, vaddr,
	182	&(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
	183
	184	pkmap_count[last_pkmap_nr] = 1;
	185	set_page_address(page, (void *)vaddr);
	186
	187	return vaddr;
	188	}
	189
77f6078a RD	190	/**
	191	* kmap_high - map a highmem page into memory
	192	* @page: &struct page to map
	193	*
	194	* Returns the page's virtual memory address.
	195	*
	196	* We cannot call this from interrupts, as it may block.
	197	*/
920c7a5d	198	void kmap_high(struct page page)
1da177e4 LT	199	{
	200	unsigned long vaddr;
	201
	202	/*
	203	* For highmem pages, we can't trust "virtual" until
	204	* after we have the lock.
1da177e4	205	*/
3297e760	206	lock_kmap();
1da177e4 LT	207	vaddr = (unsigned long)page_address(page);
	208	if (!vaddr)
	209	vaddr = map_new_virtual(page);
	210	pkmap_count[PKMAP_NR(vaddr)]++;
75babcac	211	BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
3297e760	212	unlock_kmap();
1da177e4 LT	213	return (void*) vaddr;
	214	}
	215
	216	EXPORT_SYMBOL(kmap_high);
	217
3297e760 NP	218	#ifdef ARCH_NEEDS_KMAP_HIGH_GET
	219	/**
	220	* kmap_high_get - pin a highmem page into memory
	221	* @page: &struct page to pin
	222	*
	223	* Returns the page's current virtual memory address, or NULL if no mapping
5e39df56	224	* exists. If and only if a non null address is returned then a
3297e760 NP	225	* matching call to kunmap_high() is necessary.
	226	*
	227	* This can be called from any context.
	228	*/
	229	void kmap_high_get(struct page page)
	230	{
	231	unsigned long vaddr, flags;
	232
	233	lock_kmap_any(flags);
	234	vaddr = (unsigned long)page_address(page);
	235	if (vaddr) {
	236	BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
	237	pkmap_count[PKMAP_NR(vaddr)]++;
	238	}
	239	unlock_kmap_any(flags);
	240	return (void*) vaddr;
	241	}
	242	#endif
	243
77f6078a RD	244	/**
	245	* kunmap_high - map a highmem page into memory
	246	* @page: &struct page to unmap
3297e760 NP	247	*
	248	* If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
	249	* only from user context.
77f6078a	250	*/
920c7a5d	251	void kunmap_high(struct page *page)
1da177e4 LT	252	{
	253	unsigned long vaddr;
	254	unsigned long nr;
3297e760	255	unsigned long flags;
1da177e4 LT	256	int need_wakeup;
1da177e4 LT	257
3297e760	258	lock_kmap_any(flags);
1da177e4	259	vaddr = (unsigned long)page_address(page);
75babcac	260	BUG_ON(!vaddr);
1da177e4 LT	261	nr = PKMAP_NR(vaddr);
	262
	263	/*
	264	* A count must never go down to zero
	265	* without a TLB flush!
	266	*/
	267	need_wakeup = 0;
	268	switch (--pkmap_count[nr]) {
	269	case 0:
	270	BUG();
	271	case 1:
	272	/*
	273	* Avoid an unnecessary wake_up() function call.
	274	* The common case is pkmap_count[] == 1, but
	275	* no waiters.
	276	* The tasks queued in the wait-queue are guarded
	277	* by both the lock in the wait-queue-head and by
	278	* the kmap_lock. As the kmap_lock is held here,
	279	* no need for the wait-queue-head's lock. Simply
	280	* test if the queue is empty.
	281	*/
	282	need_wakeup = waitqueue_active(&pkmap_map_wait);
	283	}
3297e760	284	unlock_kmap_any(flags);
1da177e4 LT	285
	286	/* do wake-up, if needed, race-free outside of the spin lock */
	287	if (need_wakeup)
	288	wake_up(&pkmap_map_wait);
	289	}
	290
	291	EXPORT_SYMBOL(kunmap_high);
1da177e4 LT	292	#endif
1da177e4 LT	293
1da177e4 LT	294	#if defined(HASHED_PAGE_VIRTUAL)
	295
	296	#define PA_HASH_ORDER 7
	297
	298	/*
	299	* Describes one page->virtual association
	300	*/
	301	struct page_address_map {
	302	struct page *page;
	303	void *virtual;
	304	struct list_head list;
	305	};
	306
	307	/*
	308	* page_address_map freelist, allocated from page_address_maps.
	309	*/
	310	static struct list_head page_address_pool; /* freelist */
	311	static spinlock_t pool_lock; /* protects page_address_pool */
	312
	313	/*
	314	* Hash table bucket
	315	*/
	316	static struct page_address_slot {
	317	struct list_head lh; /* List of page_address_maps */
	318	spinlock_t lock; /* Protect this bucket's list */
	319	} ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
	320
	321	static struct page_address_slot page_slot(struct page page)
	322	{
	323	return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
	324	}
	325
77f6078a RD	326	/**
	327	* page_address - get the mapped virtual address of a page
	328	* @page: &struct page to get the virtual address of
	329	*
	330	* Returns the page's virtual address.
	331	*/
1da177e4 LT	332	void page_address(struct page page)
	333	{
	334	unsigned long flags;
	335	void *ret;
	336	struct page_address_slot *pas;
	337
	338	if (!PageHighMem(page))
	339	return lowmem_page_address(page);
	340
	341	pas = page_slot(page);
	342	ret = NULL;
	343	spin_lock_irqsave(&pas->lock, flags);
	344	if (!list_empty(&pas->lh)) {
	345	struct page_address_map *pam;
	346
	347	list_for_each_entry(pam, &pas->lh, list) {
	348	if (pam->page == page) {
	349	ret = pam->virtual;
	350	goto done;
	351	}
	352	}
	353	}
	354	done:
	355	spin_unlock_irqrestore(&pas->lock, flags);
	356	return ret;
	357	}
	358
	359	EXPORT_SYMBOL(page_address);
	360
77f6078a RD	361	/**
	362	* set_page_address - set a page's virtual address
	363	* @page: &struct page to set
	364	* @virtual: virtual address to use
	365	*/
1da177e4 LT	366	void set_page_address(struct page page, void virtual)
	367	{
	368	unsigned long flags;
	369	struct page_address_slot *pas;
	370	struct page_address_map *pam;
	371
	372	BUG_ON(!PageHighMem(page));
	373
	374	pas = page_slot(page);
	375	if (virtual) { /* Add */
	376	BUG_ON(list_empty(&page_address_pool));
	377
	378	spin_lock_irqsave(&pool_lock, flags);
	379	pam = list_entry(page_address_pool.next,
	380	struct page_address_map, list);
	381	list_del(&pam->list);
	382	spin_unlock_irqrestore(&pool_lock, flags);
	383
	384	pam->page = page;
	385	pam->virtual = virtual;
	386
	387	spin_lock_irqsave(&pas->lock, flags);
	388	list_add_tail(&pam->list, &pas->lh);
	389	spin_unlock_irqrestore(&pas->lock, flags);
	390	} else { /* Remove */
	391	spin_lock_irqsave(&pas->lock, flags);
	392	list_for_each_entry(pam, &pas->lh, list) {
	393	if (pam->page == page) {
	394	list_del(&pam->list);
	395	spin_unlock_irqrestore(&pas->lock, flags);
	396	spin_lock_irqsave(&pool_lock, flags);
	397	list_add_tail(&pam->list, &page_address_pool);
	398	spin_unlock_irqrestore(&pool_lock, flags);
	399	goto done;
	400	}
	401	}
	402	spin_unlock_irqrestore(&pas->lock, flags);
	403	}
	404	done:
	405	return;
	406	}
	407
	408	static struct page_address_map page_address_maps[LAST_PKMAP];
	409
	410	void __init page_address_init(void)
	411	{
	412	int i;
	413
	414	INIT_LIST_HEAD(&page_address_pool);
	415	for (i = 0; i < ARRAY_SIZE(page_address_maps); i++)
	416	list_add(&page_address_maps[i].list, &page_address_pool);
	417	for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
	418	INIT_LIST_HEAD(&page_address_htable[i].lh);
	419	spin_lock_init(&page_address_htable[i].lock);
	420	}
	421	spin_lock_init(&pool_lock);
	422	}
	423
	424	#endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */
f4112de6	425
ff3d58c2	426	#ifdef CONFIG_DEBUG_HIGHMEM
f4112de6 AM	427
	428	void debug_kmap_atomic(enum km_type type)
	429	{
5ebd4c22	430	static int warn_count = 10;
f4112de6	431
5ebd4c22	432	if (unlikely(warn_count < 0))
f4112de6 AM	433	return;
	434
	435	if (unlikely(in_interrupt())) {
d4515646 SS	436	if (in_nmi()) {
	437	if (type != KM_NMI && type != KM_NMI_PTE) {
	438	WARN_ON(1);
	439	warn_count--;
	440	}
	441	} else if (in_irq()) {
f4112de6 AM	442	if (type != KM_IRQ0 && type != KM_IRQ1 &&
f4112de6 AM	443	type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
d4515646	444	type != KM_BOUNCE_READ && type != KM_IRQ_PTE) {
f4112de6 AM	445	WARN_ON(1);
	446	warn_count--;
	447	}
	448	} else if (!irqs_disabled()) { /* softirq */
	449	if (type != KM_IRQ0 && type != KM_IRQ1 &&
	450	type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
	451	type != KM_SKB_SUNRPC_DATA &&
	452	type != KM_SKB_DATA_SOFTIRQ &&
	453	type != KM_BOUNCE_READ) {
	454	WARN_ON(1);
	455	warn_count--;
	456	}
	457	}
	458	}
	459
	460	if (type == KM_IRQ0 \|\| type == KM_IRQ1 \|\| type == KM_BOUNCE_READ \|\|
d4515646 SS	461	type == KM_BIO_SRC_IRQ \|\| type == KM_BIO_DST_IRQ \|\|
	462	type == KM_IRQ_PTE \|\| type == KM_NMI \|\|
	463	type == KM_NMI_PTE ) {
f4112de6 AM	464	if (!irqs_disabled()) {
	465	WARN_ON(1);
	466	warn_count--;
	467	}
	468	} else if (type == KM_SOFTIRQ0 \|\| type == KM_SOFTIRQ1) {
	469	if (irq_count() == 0 && !irqs_disabled()) {
	470	WARN_ON(1);
	471	warn_count--;
	472	}
	473	}
eac79005 JW	474	#ifdef CONFIG_KGDB_KDB
	475	if (unlikely(type == KM_KDB && atomic_read(&kgdb_active) == -1)) {
	476	WARN_ON(1);
	477	warn_count--;
	478	}
	479	#endif /* CONFIG_KGDB_KDB */
f4112de6 AM	480	}
	481
	482	#endif