[thirdparty/linux.git] / mm / highmem.c

// SPDX-License-Identifier: GPL-2.0
/*
 * 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/export.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>
#include <linux/vmalloc.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

/*
 * Architecture with aliasing data cache may define the following family of
 * helper functions in its asm/highmem.h to control cache color of virtual
 * addresses where physical memory pages are mapped by kmap.
 */
#ifndef get_pkmap_color

/*
 * Determine color of virtual address where the page should be mapped.
 */
static inline unsigned int get_pkmap_color(struct page *page)
{
	return 0;
}
#define get_pkmap_color get_pkmap_color

/*
 * Get next index for mapping inside PKMAP region for page with given color.
 */
static inline unsigned int get_next_pkmap_nr(unsigned int color)
{
	static unsigned int last_pkmap_nr;

	last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
	return last_pkmap_nr;
}

/*
 * Determine if page index inside PKMAP region (pkmap_nr) of given color
 * has wrapped around PKMAP region end. When this happens an attempt to
 * flush all unused PKMAP slots is made.
 */
static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)
{
	return pkmap_nr == 0;
}

/*
 * Get the number of PKMAP entries of the given color. If no free slot is
 * found after checking that many entries, kmap will sleep waiting for
 * someone to call kunmap and free PKMAP slot.
 */
static inline int get_pkmap_entries_count(unsigned int color)
{
	return LAST_PKMAP;
}

/*
 * Get head of a wait queue for PKMAP entries of the given color.
 * Wait queues for different mapping colors should be independent to avoid
 * unnecessary wakeups caused by freeing of slots of other colors.
 */
static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
{
	static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);

	return &pkmap_map_wait;
}
#endif

atomic_long_t _totalhigh_pages __read_mostly;
EXPORT_SYMBOL(_totalhigh_pages);

unsigned int __nr_free_highpages (void)
{
	struct zone *zone;
	unsigned int pages = 0;

	for_each_populated_zone(zone) {
		if (is_highmem(zone))
			pages += zone_page_state(zone, NR_FREE_PAGES);
	}

	return pages;
}

static int pkmap_count[LAST_PKMAP];
static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);

pte_t * pkmap_page_table;

/*
 * 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

struct page *__kmap_to_page(void *vaddr)
{
	unsigned long addr = (unsigned long)vaddr;

	if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
		int i = PKMAP_NR(addr);
		return pte_page(pkmap_page_table[i]);
	}

	return virt_to_page(addr);
}
EXPORT_SYMBOL(__kmap_to_page);

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, PKMAP_ADDR(i), &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));
}

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;
	unsigned int last_pkmap_nr;
	unsigned int color = get_pkmap_color(page);

start:
	count = get_pkmap_entries_count(color);
	/* Find an empty entry */
	for (;;) {
		last_pkmap_nr = get_next_pkmap_nr(color);
		if (no_more_pkmaps(last_pkmap_nr, color)) {
			flush_all_zero_pkmaps();
			count = get_pkmap_entries_count(color);
		}
		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);
			wait_queue_head_t *pkmap_map_wait =
				get_pkmap_wait_queue_head(color);

			__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 - unmap 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;
	unsigned int color = get_pkmap_color(page);
	wait_queue_head_t *pkmap_map_wait;

	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.
		 */
		pkmap_map_wait = get_pkmap_wait_queue_head(color);
		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 /* CONFIG_HIGHMEM */

#ifdef CONFIG_KMAP_LOCAL

#include <asm/kmap_size.h>

static DEFINE_PER_CPU(int, __kmap_local_idx);

/*
 * With DEBUG_KMAP_LOCAL the stack depth is doubled and every second
 * slot is unused which acts as a guard page
 */
#ifdef CONFIG_DEBUG_KMAP_LOCAL
# define KM_INCR	2
#else
# define KM_INCR	1
#endif

static inline int kmap_local_idx_push(void)
{
	int idx = __this_cpu_add_return(__kmap_local_idx, KM_INCR) - 1;

	WARN_ON_ONCE(in_irq() && !irqs_disabled());
	BUG_ON(idx >= KM_MAX_IDX);
	return idx;
}

static inline int kmap_local_idx(void)
{
	return __this_cpu_read(__kmap_local_idx) - 1;
}

static inline void kmap_local_idx_pop(void)
{
	int idx = __this_cpu_sub_return(__kmap_local_idx, KM_INCR);

	BUG_ON(idx < 0);
}

#ifndef arch_kmap_local_post_map
# define arch_kmap_local_post_map(vaddr, pteval)	do { } while (0)
#endif

#ifndef arch_kmap_local_pre_unmap
# define arch_kmap_local_pre_unmap(vaddr)		do { } while (0)
#endif

#ifndef arch_kmap_local_post_unmap
# define arch_kmap_local_post_unmap(vaddr)		do { } while (0)
#endif

#ifndef arch_kmap_local_map_idx
#define arch_kmap_local_map_idx(idx, pfn)	kmap_local_calc_idx(idx)
#endif

#ifndef arch_kmap_local_unmap_idx
#define arch_kmap_local_unmap_idx(idx, vaddr)	kmap_local_calc_idx(idx)
#endif

#ifndef arch_kmap_local_high_get
static inline void *arch_kmap_local_high_get(struct page *page)
{
	return NULL;
}
#endif

/* Unmap a local mapping which was obtained by kmap_high_get() */
static inline bool kmap_high_unmap_local(unsigned long vaddr)
{
#ifdef ARCH_NEEDS_KMAP_HIGH_GET
	if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
		return true;
	}
#endif
	return false;
}

static inline int kmap_local_calc_idx(int idx)
{
	return idx + KM_MAX_IDX * smp_processor_id();
}

static pte_t *__kmap_pte;

static pte_t *kmap_get_pte(void)
{
	if (!__kmap_pte)
		__kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
	return __kmap_pte;
}

void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
{
	pte_t pteval, *kmap_pte = kmap_get_pte();
	unsigned long vaddr;
	int idx;

	preempt_disable();
	idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn);
	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
	BUG_ON(!pte_none(*(kmap_pte - idx)));
	pteval = pfn_pte(pfn, prot);
	set_pte_at(&init_mm, vaddr, kmap_pte - idx, pteval);
	arch_kmap_local_post_map(vaddr, pteval);
	preempt_enable();

	return (void *)vaddr;
}
EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot);

void *__kmap_local_page_prot(struct page *page, pgprot_t prot)
{
	void *kmap;

	if (!PageHighMem(page))
		return page_address(page);

	/* Try kmap_high_get() if architecture has it enabled */
	kmap = arch_kmap_local_high_get(page);
	if (kmap)
		return kmap;

	return __kmap_local_pfn_prot(page_to_pfn(page), prot);
}
EXPORT_SYMBOL(__kmap_local_page_prot);

void kunmap_local_indexed(void *vaddr)
{
	unsigned long addr = (unsigned long) vaddr & PAGE_MASK;
	pte_t *kmap_pte = kmap_get_pte();
	int idx;

	if (addr < __fix_to_virt(FIX_KMAP_END) ||
	    addr > __fix_to_virt(FIX_KMAP_BEGIN)) {
		/*
		 * Handle mappings which were obtained by kmap_high_get()
		 * first as the virtual address of such mappings is below
		 * PAGE_OFFSET. Warn for all other addresses which are in
		 * the user space part of the virtual address space.
		 */
		if (!kmap_high_unmap_local(addr))
			WARN_ON_ONCE(addr < PAGE_OFFSET);
		return;
	}

	preempt_disable();
	idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);
	WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));

	arch_kmap_local_pre_unmap(addr);
	pte_clear(&init_mm, addr, kmap_pte - idx);
	arch_kmap_local_post_unmap(addr);
	kmap_local_idx_pop();
	preempt_enable();
}
EXPORT_SYMBOL(kunmap_local_indexed);
#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;
};

static struct page_address_map page_address_maps[LAST_PKMAP];

/*
 * 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(const 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(const 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 */
		pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)];
		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);
				goto done;
			}
		}
		spin_unlock_irqrestore(&pas->lock, flags);
	}
done:
	return;
}

void __init page_address_init(void)
{
	int i;

	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);
	}
}

#endif	/* defined(HASHED_PAGE_VIRTUAL) */
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	3	* High memory handling common code and variables.
	4	*
	5	* (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de
	6	* Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de
	7	*
	8	*
	9	* Redesigned the x86 32-bit VM architecture to deal with
	10	* 64-bit physical space. With current x86 CPUs this
	11	* means up to 64 Gigabytes physical RAM.
	12	*
	13	* Rewrote high memory support to move the page cache into
	14	* high memory. Implemented permanent (schedulable) kmaps
	15	* based on Linus' idea.
	16	*
	17	* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
	18	*/
	19
	20	#include <linux/mm.h>
b95f1b31	21	#include <linux/export.h>
1da177e4 LT	22	#include <linux/swap.h>
	23	#include <linux/bio.h>
	24	#include <linux/pagemap.h>
	25	#include <linux/mempool.h>
	26	#include <linux/blkdev.h>
	27	#include <linux/init.h>
	28	#include <linux/hash.h>
	29	#include <linux/highmem.h>
eac79005	30	#include <linux/kgdb.h>
1da177e4	31	#include <asm/tlbflush.h>
186525bd	32	#include <linux/vmalloc.h>
a8e23a29	33
1da177e4 LT	34	/*
	35	* Virtual_count is not a pure "count".
	36	* 0 means that it is not mapped, and has not been mapped
	37	* since a TLB flush - it is usable.
	38	* 1 means that there are no users, but it has been mapped
	39	* since the last TLB flush - so we can't use it.
	40	* n means that there are (n-1) current users of it.
	41	*/
	42	#ifdef CONFIG_HIGHMEM
260b2367	43
15de36a4 MF	44	/*
	45	* Architecture with aliasing data cache may define the following family of
	46	* helper functions in its asm/highmem.h to control cache color of virtual
	47	* addresses where physical memory pages are mapped by kmap.
	48	*/
	49	#ifndef get_pkmap_color
	50
	51	/*
	52	* Determine color of virtual address where the page should be mapped.
	53	*/
	54	static inline unsigned int get_pkmap_color(struct page *page)
	55	{
	56	return 0;
	57	}
	58	#define get_pkmap_color get_pkmap_color
	59
	60	/*
	61	* Get next index for mapping inside PKMAP region for page with given color.
	62	*/
	63	static inline unsigned int get_next_pkmap_nr(unsigned int color)
	64	{
	65	static unsigned int last_pkmap_nr;
	66
	67	last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
	68	return last_pkmap_nr;
	69	}
	70
	71	/*
	72	* Determine if page index inside PKMAP region (pkmap_nr) of given color
	73	* has wrapped around PKMAP region end. When this happens an attempt to
	74	* flush all unused PKMAP slots is made.
	75	*/
	76	static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)
	77	{
	78	return pkmap_nr == 0;
	79	}
	80
	81	/*
	82	* Get the number of PKMAP entries of the given color. If no free slot is
	83	* found after checking that many entries, kmap will sleep waiting for
	84	* someone to call kunmap and free PKMAP slot.
	85	*/
	86	static inline int get_pkmap_entries_count(unsigned int color)
	87	{
	88	return LAST_PKMAP;
	89	}
	90
	91	/*
	92	* Get head of a wait queue for PKMAP entries of the given color.
	93	* Wait queues for different mapping colors should be independent to avoid
	94	* unnecessary wakeups caused by freeing of slots of other colors.
	95	*/
	96	static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
	97	{
	98	static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
	99
	100	return &pkmap_map_wait;
	101	}
	102	#endif
	103
ca79b0c2 AK	104	atomic_long_t _totalhigh_pages __read_mostly;
ca79b0c2 AK	105	EXPORT_SYMBOL(_totalhigh_pages);
3e4d3af5	106
13f876ba	107	unsigned int __nr_free_highpages (void)
c1f60a5a	108	{
33499bfe	109	struct zone *zone;
c1f60a5a CL	110	unsigned int pages = 0;
c1f60a5a CL	111
33499bfe JK	112	for_each_populated_zone(zone) {
	113	if (is_highmem(zone))
	114	pages += zone_page_state(zone, NR_FREE_PAGES);
2a1e274a	115	}
c1f60a5a CL	116
	117	return pages;
	118	}
	119
1da177e4	120	static int pkmap_count[LAST_PKMAP];
1da177e4 LT	121	static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
	122
	123	pte_t * pkmap_page_table;
	124
3297e760 NP	125	/*
	126	* Most architectures have no use for kmap_high_get(), so let's abstract
	127	* the disabling of IRQ out of the locking in that case to save on a
	128	* potential useless overhead.
	129	*/
	130	#ifdef ARCH_NEEDS_KMAP_HIGH_GET
	131	#define lock_kmap() spin_lock_irq(&kmap_lock)
	132	#define unlock_kmap() spin_unlock_irq(&kmap_lock)
	133	#define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags)
	134	#define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags)
	135	#else
	136	#define lock_kmap() spin_lock(&kmap_lock)
	137	#define unlock_kmap() spin_unlock(&kmap_lock)
	138	#define lock_kmap_any(flags) \
	139	do { spin_lock(&kmap_lock); (void)(flags); } while (0)
	140	#define unlock_kmap_any(flags) \
	141	do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
	142	#endif
	143
13f876ba	144	struct page __kmap_to_page(void vaddr)
5a178119 MG	145	{
	146	unsigned long addr = (unsigned long)vaddr;
	147
498c2280	148	if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
4de22c05	149	int i = PKMAP_NR(addr);
5a178119 MG	150	return pte_page(pkmap_page_table[i]);
	151	}
	152
	153	return virt_to_page(addr);
	154	}
13f876ba	155	EXPORT_SYMBOL(__kmap_to_page);
5a178119	156
1da177e4 LT	157	static void flush_all_zero_pkmaps(void)
	158	{
	159	int i;
5843d9a4	160	int need_flush = 0;
1da177e4 LT	161
	162	flush_cache_kmaps();
	163
	164	for (i = 0; i < LAST_PKMAP; i++) {
	165	struct page *page;
	166
	167	/*
	168	* zero means we don't have anything to do,
	169	* >1 means that it is still in use. Only
	170	* a count of 1 means that it is free but
	171	* needs to be unmapped
	172	*/
	173	if (pkmap_count[i] != 1)
	174	continue;
	175	pkmap_count[i] = 0;
	176
	177	/* sanity check */
75babcac	178	BUG_ON(pte_none(pkmap_page_table[i]));
1da177e4 LT	179
	180	/*
	181	* Don't need an atomic fetch-and-clear op here;
	182	* no-one has the page mapped, and cannot get at
	183	* its virtual address (and hence PTE) without first
	184	* getting the kmap_lock (which is held here).
	185	* So no dangers, even with speculative execution.
	186	*/
	187	page = pte_page(pkmap_page_table[i]);
eb2db439	188	pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]);
1da177e4 LT	189
1da177e4 LT	190	set_page_address(page, NULL);
5843d9a4	191	need_flush = 1;
1da177e4	192	}
5843d9a4 NP	193	if (need_flush)
5843d9a4 NP	194	flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
1da177e4 LT	195	}
1da177e4 LT	196
13f876ba	197	void __kmap_flush_unused(void)
ce6234b5	198	{
3297e760	199	lock_kmap();
ce6234b5	200	flush_all_zero_pkmaps();
3297e760	201	unlock_kmap();
ce6234b5 JF	202	}
ce6234b5 JF	203
1da177e4 LT	204	static inline unsigned long map_new_virtual(struct page *page)
	205	{
	206	unsigned long vaddr;
	207	int count;
15de36a4 MF	208	unsigned int last_pkmap_nr;
15de36a4 MF	209	unsigned int color = get_pkmap_color(page);
1da177e4 LT	210
1da177e4 LT	211	start:
15de36a4	212	count = get_pkmap_entries_count(color);
1da177e4 LT	213	/* Find an empty entry */
1da177e4 LT	214	for (;;) {
15de36a4 MF	215	last_pkmap_nr = get_next_pkmap_nr(color);
15de36a4 MF	216	if (no_more_pkmaps(last_pkmap_nr, color)) {
1da177e4	217	flush_all_zero_pkmaps();
15de36a4	218	count = get_pkmap_entries_count(color);
1da177e4 LT	219	}
	220	if (!pkmap_count[last_pkmap_nr])
	221	break; /* Found a usable entry */
	222	if (--count)
	223	continue;
	224
	225	/*
	226	* Sleep for somebody else to unmap their entries
	227	*/
	228	{
	229	DECLARE_WAITQUEUE(wait, current);
15de36a4 MF	230	wait_queue_head_t *pkmap_map_wait =
15de36a4 MF	231	get_pkmap_wait_queue_head(color);
1da177e4 LT	232
1da177e4 LT	233	__set_current_state(TASK_UNINTERRUPTIBLE);
15de36a4	234	add_wait_queue(pkmap_map_wait, &wait);
3297e760	235	unlock_kmap();
1da177e4	236	schedule();
15de36a4	237	remove_wait_queue(pkmap_map_wait, &wait);
3297e760	238	lock_kmap();
1da177e4 LT	239
	240	/* Somebody else might have mapped it while we slept */
	241	if (page_address(page))
	242	return (unsigned long)page_address(page);
	243
	244	/* Re-start */
	245	goto start;
	246	}
	247	}
	248	vaddr = PKMAP_ADDR(last_pkmap_nr);
	249	set_pte_at(&init_mm, vaddr,
	250	&(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
	251
	252	pkmap_count[last_pkmap_nr] = 1;
	253	set_page_address(page, (void *)vaddr);
	254
	255	return vaddr;
	256	}
	257
77f6078a RD	258	/**
	259	* kmap_high - map a highmem page into memory
	260	* @page: &struct page to map
	261	*
	262	* Returns the page's virtual memory address.
	263	*
	264	* We cannot call this from interrupts, as it may block.
	265	*/
920c7a5d	266	void kmap_high(struct page page)
1da177e4 LT	267	{
	268	unsigned long vaddr;
	269
	270	/*
	271	* For highmem pages, we can't trust "virtual" until
	272	* after we have the lock.
1da177e4	273	*/
3297e760	274	lock_kmap();
1da177e4 LT	275	vaddr = (unsigned long)page_address(page);
	276	if (!vaddr)
	277	vaddr = map_new_virtual(page);
	278	pkmap_count[PKMAP_NR(vaddr)]++;
75babcac	279	BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
3297e760	280	unlock_kmap();
1da177e4 LT	281	return (void*) vaddr;
	282	}
	283
	284	EXPORT_SYMBOL(kmap_high);
	285
3297e760 NP	286	#ifdef ARCH_NEEDS_KMAP_HIGH_GET
	287	/**
	288	* kmap_high_get - pin a highmem page into memory
	289	* @page: &struct page to pin
	290	*
	291	* Returns the page's current virtual memory address, or NULL if no mapping
5e39df56	292	* exists. If and only if a non null address is returned then a
3297e760 NP	293	* matching call to kunmap_high() is necessary.
	294	*
	295	* This can be called from any context.
	296	*/
	297	void kmap_high_get(struct page page)
	298	{
	299	unsigned long vaddr, flags;
	300
	301	lock_kmap_any(flags);
	302	vaddr = (unsigned long)page_address(page);
	303	if (vaddr) {
	304	BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
	305	pkmap_count[PKMAP_NR(vaddr)]++;
	306	}
	307	unlock_kmap_any(flags);
	308	return (void*) vaddr;
	309	}
	310	#endif
	311
77f6078a	312	/**
4e9dc5df	313	* kunmap_high - unmap a highmem page into memory
77f6078a	314	* @page: &struct page to unmap
3297e760 NP	315	*
	316	* If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
	317	* only from user context.
77f6078a	318	*/
920c7a5d	319	void kunmap_high(struct page *page)
1da177e4 LT	320	{
	321	unsigned long vaddr;
	322	unsigned long nr;
3297e760	323	unsigned long flags;
1da177e4	324	int need_wakeup;
15de36a4 MF	325	unsigned int color = get_pkmap_color(page);
15de36a4 MF	326	wait_queue_head_t *pkmap_map_wait;
1da177e4	327
3297e760	328	lock_kmap_any(flags);
1da177e4	329	vaddr = (unsigned long)page_address(page);
75babcac	330	BUG_ON(!vaddr);
1da177e4 LT	331	nr = PKMAP_NR(vaddr);
	332
	333	/*
	334	* A count must never go down to zero
	335	* without a TLB flush!
	336	*/
	337	need_wakeup = 0;
	338	switch (--pkmap_count[nr]) {
	339	case 0:
	340	BUG();
	341	case 1:
	342	/*
	343	* Avoid an unnecessary wake_up() function call.
	344	* The common case is pkmap_count[] == 1, but
	345	* no waiters.
	346	* The tasks queued in the wait-queue are guarded
	347	* by both the lock in the wait-queue-head and by
	348	* the kmap_lock. As the kmap_lock is held here,
	349	* no need for the wait-queue-head's lock. Simply
	350	* test if the queue is empty.
	351	*/
15de36a4 MF	352	pkmap_map_wait = get_pkmap_wait_queue_head(color);
15de36a4 MF	353	need_wakeup = waitqueue_active(pkmap_map_wait);
1da177e4	354	}
3297e760	355	unlock_kmap_any(flags);
1da177e4 LT	356
	357	/* do wake-up, if needed, race-free outside of the spin lock */
	358	if (need_wakeup)
15de36a4	359	wake_up(pkmap_map_wait);
1da177e4	360	}
1da177e4	361	EXPORT_SYMBOL(kunmap_high);
298fa1ad TG	362	#endif /* CONFIG_HIGHMEM */
	363
	364	#ifdef CONFIG_KMAP_LOCAL
	365
	366	#include <asm/kmap_size.h>
	367
	368	static DEFINE_PER_CPU(int, __kmap_local_idx);
	369
389755c2	370	/*
6e799cb6	371	* With DEBUG_KMAP_LOCAL the stack depth is doubled and every second
389755c2 TG	372	* slot is unused which acts as a guard page
389755c2 TG	373	*/
6e799cb6	374	#ifdef CONFIG_DEBUG_KMAP_LOCAL
389755c2 TG	375	# define KM_INCR 2
	376	#else
	377	# define KM_INCR 1
	378	#endif
	379
298fa1ad TG	380	static inline int kmap_local_idx_push(void)
298fa1ad TG	381	{
389755c2	382	int idx = __this_cpu_add_return(__kmap_local_idx, KM_INCR) - 1;
298fa1ad TG	383
	384	WARN_ON_ONCE(in_irq() && !irqs_disabled());
	385	BUG_ON(idx >= KM_MAX_IDX);
	386	return idx;
	387	}
	388
	389	static inline int kmap_local_idx(void)
	390	{
	391	return __this_cpu_read(__kmap_local_idx) - 1;
	392	}
	393
	394	static inline void kmap_local_idx_pop(void)
	395	{
389755c2	396	int idx = __this_cpu_sub_return(__kmap_local_idx, KM_INCR);
298fa1ad TG	397
	398	BUG_ON(idx < 0);
	399	}
	400
	401	#ifndef arch_kmap_local_post_map
	402	# define arch_kmap_local_post_map(vaddr, pteval) do { } while (0)
	403	#endif
3c1016b5	404
298fa1ad TG	405	#ifndef arch_kmap_local_pre_unmap
	406	# define arch_kmap_local_pre_unmap(vaddr) do { } while (0)
	407	#endif
	408
	409	#ifndef arch_kmap_local_post_unmap
	410	# define arch_kmap_local_post_unmap(vaddr) do { } while (0)
	411	#endif
	412
	413	#ifndef arch_kmap_local_map_idx
	414	#define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx)
	415	#endif
	416
	417	#ifndef arch_kmap_local_unmap_idx
	418	#define arch_kmap_local_unmap_idx(idx, vaddr) kmap_local_calc_idx(idx)
	419	#endif
	420
	421	#ifndef arch_kmap_local_high_get
	422	static inline void arch_kmap_local_high_get(struct page page)
	423	{
	424	return NULL;
	425	}
	426	#endif
	427
	428	/* Unmap a local mapping which was obtained by kmap_high_get() */
2a656cad	429	static inline bool kmap_high_unmap_local(unsigned long vaddr)
298fa1ad TG	430	{
298fa1ad TG	431	#ifdef ARCH_NEEDS_KMAP_HIGH_GET
2a656cad	432	if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
298fa1ad	433	kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
2a656cad TG	434	return true;
2a656cad TG	435	}
298fa1ad	436	#endif
2a656cad	437	return false;
298fa1ad TG	438	}
	439
	440	static inline int kmap_local_calc_idx(int idx)
	441	{
	442	return idx + KM_MAX_IDX * smp_processor_id();
	443	}
	444
	445	static pte_t *__kmap_pte;
	446
	447	static pte_t *kmap_get_pte(void)
	448	{
	449	if (!__kmap_pte)
	450	__kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
	451	return __kmap_pte;
	452	}
	453
	454	void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
	455	{
	456	pte_t pteval, *kmap_pte = kmap_get_pte();
	457	unsigned long vaddr;
	458	int idx;
	459
	460	preempt_disable();
	461	idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn);
	462	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
	463	BUG_ON(!pte_none(*(kmap_pte - idx)));
	464	pteval = pfn_pte(pfn, prot);
	465	set_pte_at(&init_mm, vaddr, kmap_pte - idx, pteval);
	466	arch_kmap_local_post_map(vaddr, pteval);
	467	preempt_enable();
	468
	469	return (void *)vaddr;
	470	}
	471	EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot);
	472
	473	void __kmap_local_page_prot(struct page page, pgprot_t prot)
	474	{
	475	void *kmap;
	476
	477	if (!PageHighMem(page))
	478	return page_address(page);
	479
	480	/* Try kmap_high_get() if architecture has it enabled */
	481	kmap = arch_kmap_local_high_get(page);
	482	if (kmap)
	483	return kmap;
	484
	485	return __kmap_local_pfn_prot(page_to_pfn(page), prot);
	486	}
	487	EXPORT_SYMBOL(__kmap_local_page_prot);
	488
	489	void kunmap_local_indexed(void *vaddr)
	490	{
	491	unsigned long addr = (unsigned long) vaddr & PAGE_MASK;
	492	pte_t *kmap_pte = kmap_get_pte();
	493	int idx;
	494
	495	if (addr < __fix_to_virt(FIX_KMAP_END) \|\|
	496	addr > __fix_to_virt(FIX_KMAP_BEGIN)) {
2a656cad TG	497	/*
	498	* Handle mappings which were obtained by kmap_high_get()
	499	* first as the virtual address of such mappings is below
	500	* PAGE_OFFSET. Warn for all other addresses which are in
	501	* the user space part of the virtual address space.
	502	*/
	503	if (!kmap_high_unmap_local(addr))
	504	WARN_ON_ONCE(addr < PAGE_OFFSET);
298fa1ad TG	505	return;
	506	}
	507
	508	preempt_disable();
	509	idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);
	510	WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
	511
	512	arch_kmap_local_pre_unmap(addr);
	513	pte_clear(&init_mm, addr, kmap_pte - idx);
	514	arch_kmap_local_post_unmap(addr);
	515	kmap_local_idx_pop();
	516	preempt_enable();
	517	}
	518	EXPORT_SYMBOL(kunmap_local_indexed);
	519	#endif
1da177e4	520
1da177e4 LT	521	#if defined(HASHED_PAGE_VIRTUAL)
	522
	523	#define PA_HASH_ORDER 7
	524
	525	/*
	526	* Describes one page->virtual association
	527	*/
	528	struct page_address_map {
	529	struct page *page;
	530	void *virtual;
	531	struct list_head list;
	532	};
	533
a354e2c8	534	static struct page_address_map page_address_maps[LAST_PKMAP];
1da177e4 LT	535
	536	/*
	537	* Hash table bucket
	538	*/
	539	static struct page_address_slot {
	540	struct list_head lh; /* List of page_address_maps */
	541	spinlock_t lock; /* Protect this bucket's list */
	542	} ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
	543
f9918794	544	static struct page_address_slot page_slot(const struct page page)
1da177e4 LT	545	{
	546	return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
	547	}
	548
77f6078a RD	549	/**
	550	* page_address - get the mapped virtual address of a page
	551	* @page: &struct page to get the virtual address of
	552	*
	553	* Returns the page's virtual address.
	554	*/
f9918794	555	void page_address(const struct page page)
1da177e4 LT	556	{
	557	unsigned long flags;
	558	void *ret;
	559	struct page_address_slot *pas;
	560
	561	if (!PageHighMem(page))
	562	return lowmem_page_address(page);
	563
	564	pas = page_slot(page);
	565	ret = NULL;
	566	spin_lock_irqsave(&pas->lock, flags);
	567	if (!list_empty(&pas->lh)) {
	568	struct page_address_map *pam;
	569
	570	list_for_each_entry(pam, &pas->lh, list) {
	571	if (pam->page == page) {
	572	ret = pam->virtual;
	573	goto done;
	574	}
	575	}
	576	}
	577	done:
	578	spin_unlock_irqrestore(&pas->lock, flags);
	579	return ret;
	580	}
	581
	582	EXPORT_SYMBOL(page_address);
	583
77f6078a RD	584	/**
	585	* set_page_address - set a page's virtual address
	586	* @page: &struct page to set
	587	* @virtual: virtual address to use
	588	*/
1da177e4 LT	589	void set_page_address(struct page page, void virtual)
	590	{
	591	unsigned long flags;
	592	struct page_address_slot *pas;
	593	struct page_address_map *pam;
	594
	595	BUG_ON(!PageHighMem(page));
	596
	597	pas = page_slot(page);
	598	if (virtual) { /* Add */
a354e2c8	599	pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)];
1da177e4 LT	600	pam->page = page;
	601	pam->virtual = virtual;
	602
	603	spin_lock_irqsave(&pas->lock, flags);
	604	list_add_tail(&pam->list, &pas->lh);
	605	spin_unlock_irqrestore(&pas->lock, flags);
	606	} else { /* Remove */
	607	spin_lock_irqsave(&pas->lock, flags);
	608	list_for_each_entry(pam, &pas->lh, list) {
	609	if (pam->page == page) {
	610	list_del(&pam->list);
	611	spin_unlock_irqrestore(&pas->lock, flags);
1da177e4 LT	612	goto done;
	613	}
	614	}
	615	spin_unlock_irqrestore(&pas->lock, flags);
	616	}
	617	done:
	618	return;
	619	}
	620
1da177e4 LT	621	void __init page_address_init(void)
	622	{
	623	int i;
	624
1da177e4 LT	625	for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
	626	INIT_LIST_HEAD(&page_address_htable[i].lh);
	627	spin_lock_init(&page_address_htable[i].lock);
	628	}
1da177e4 LT	629	}
1da177e4 LT	630
955cc774	631	#endif /* defined(HASHED_PAGE_VIRTUAL) */