LXR linux/arch/x86/mm/highmem

   1#include <linux/highmem.h>
   2#include <linux/module.h>
   3#include <linux/swap.h> /* for totalram_pages */
   4
   5void *kmap(struct page *page)
   6{
   7        might_sleep();
   8        if (!PageHighMem(page))
   9                return page_address(page);
  10        return kmap_high(page);
  11}
  12
  13void kunmap(struct page *page)
  14{
  15        if (in_interrupt())
  16                BUG();
  17        if (!PageHighMem(page))
  18                return;
  19        kunmap_high(page);
  20}
  21
  22/*
  23 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  24 * no global lock is needed and because the kmap code must perform a global TLB
  25 * invalidation when the kmap pool wraps.
  26 *
  27 * However when holding an atomic kmap it is not legal to sleep, so atomic
  28 * kmaps are appropriate for short, tight code paths only.
  29 */
  30void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
  31{
  32        enum fixed_addresses idx;
  33        unsigned long vaddr;
  34
  35        /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  36        pagefault_disable();
  37
  38        if (!PageHighMem(page))
  39                return page_address(page);
  40
  41        debug_kmap_atomic(type);
  42
  43        idx = type + KM_TYPE_NR*smp_processor_id();
  44        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  45        BUG_ON(!pte_none(*(kmap_pte-idx)));
  46        set_pte(kmap_pte-idx, mk_pte(page, prot));
  47
  48        return (void *)vaddr;
  49}
  50
  51void *kmap_atomic(struct page *page, enum km_type type)
  52{
  53        return kmap_atomic_prot(page, type, kmap_prot);
  54}
  55
  56void kunmap_atomic(void *kvaddr, enum km_type type)
  57{
  58        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  59        enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  60
  61        /*
  62         * Force other mappings to Oops if they'll try to access this pte
  63         * without first remap it.  Keeping stale mappings around is a bad idea
  64         * also, in case the page changes cacheability attributes or becomes
  65         * a protected page in a hypervisor.
  66         */
  67        if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
  68                kpte_clear_flush(kmap_pte-idx, vaddr);
  69        else {
  70#ifdef CONFIG_DEBUG_HIGHMEM
  71                BUG_ON(vaddr < PAGE_OFFSET);
  72                BUG_ON(vaddr >= (unsigned long)high_memory);
  73#endif
  74        }
  75
  76        pagefault_enable();
  77}
  78
  79/*
  80 * This is the same as kmap_atomic() but can map memory that doesn't
  81 * have a struct page associated with it.
  82 */
  83void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  84{
  85        return kmap_atomic_prot_pfn(pfn, type, kmap_prot);
  86}
  87EXPORT_SYMBOL_GPL(kmap_atomic_pfn); /* temporarily in use by i915 GEM until vmap */
  88
  89struct page *kmap_atomic_to_page(void *ptr)
  90{
  91        unsigned long idx, vaddr = (unsigned long)ptr;
  92        pte_t *pte;
  93
  94        if (vaddr < FIXADDR_START)
  95                return virt_to_page(ptr);
  96
  97        idx = virt_to_fix(vaddr);
  98        pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
  99        return pte_page(*pte);
 100}
 101
 102EXPORT_SYMBOL(kmap);
 103EXPORT_SYMBOL(kunmap);
 104EXPORT_SYMBOL(kmap_atomic);
 105EXPORT_SYMBOL(kunmap_atomic);
 106EXPORT_SYMBOL(kmap_atomic_prot);
 107EXPORT_SYMBOL(kmap_atomic_to_page);
 108
 109void __init set_highmem_pages_init(void)
 110{
 111        struct zone *zone;
 112        int nid;
 113
 114        for_each_zone(zone) {
 115                unsigned long zone_start_pfn, zone_end_pfn;
 116
 117                if (!is_highmem(zone))
 118                        continue;
 119
 120                zone_start_pfn = zone->zone_start_pfn;
 121                zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 122
 123                nid = zone_to_nid(zone);
 124                printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 125                                zone->name, nid, zone_start_pfn, zone_end_pfn);
 126
 127                add_highpages_with_active_regions(nid, zone_start_pfn,
 128                                 zone_end_pfn);
 129        }
 130        totalram_pages += totalhigh_pages;
 131}
 132