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}
  12EXPORT_SYMBOL(kmap);
  13
  14void kunmap(struct page *page)
  15{
  16        if (in_interrupt())
  17                BUG();
  18        if (!PageHighMem(page))
  19                return;
  20        kunmap_high(page);
  21}
  22EXPORT_SYMBOL(kunmap);
  23
  24/*
  25 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  26 * no global lock is needed and because the kmap code must perform a global TLB
  27 * invalidation when the kmap pool wraps.
  28 *
  29 * However when holding an atomic kmap it is not legal to sleep, so atomic
  30 * kmaps are appropriate for short, tight code paths only.
  31 */
  32void *kmap_atomic_prot(struct page *page, pgprot_t prot)
  33{
  34        unsigned long vaddr;
  35        int idx, type;
  36
  37        /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  38        pagefault_disable();
  39
  40        if (!PageHighMem(page))
  41                return page_address(page);
  42
  43        type = kmap_atomic_idx_push();
  44        idx = type + KM_TYPE_NR*smp_processor_id();
  45        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  46        BUG_ON(!pte_none(*(kmap_pte-idx)));
  47        set_pte(kmap_pte-idx, mk_pte(page, prot));
  48
  49        return (void *)vaddr;
  50}
  51EXPORT_SYMBOL(kmap_atomic_prot);
  52
  53void *__kmap_atomic(struct page *page)
  54{
  55        return kmap_atomic_prot(page, kmap_prot);
  56}
  57EXPORT_SYMBOL(__kmap_atomic);
  58
  59/*
  60 * This is the same as kmap_atomic() but can map memory that doesn't
  61 * have a struct page associated with it.
  62 */
  63void *kmap_atomic_pfn(unsigned long pfn)
  64{
  65        return kmap_atomic_prot_pfn(pfn, kmap_prot);
  66}
  67EXPORT_SYMBOL_GPL(kmap_atomic_pfn);
  68
  69void __kunmap_atomic(void *kvaddr)
  70{
  71        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  72
  73        if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
  74            vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
  75                int idx, type;
  76
  77                type = kmap_atomic_idx();
  78                idx = type + KM_TYPE_NR * smp_processor_id();
  79
  80#ifdef CONFIG_DEBUG_HIGHMEM
  81                WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  82#endif
  83                /*
  84                 * Force other mappings to Oops if they'll try to access this
  85                 * pte without first remap it.  Keeping stale mappings around
  86                 * is a bad idea also, in case the page changes cacheability
  87                 * attributes or becomes a protected page in a hypervisor.
  88                 */
  89                kpte_clear_flush(kmap_pte-idx, vaddr);
  90                kmap_atomic_idx_pop();
  91        }
  92#ifdef CONFIG_DEBUG_HIGHMEM
  93        else {
  94                BUG_ON(vaddr < PAGE_OFFSET);
  95                BUG_ON(vaddr >= (unsigned long)high_memory);
  96        }
  97#endif
  98
  99        pagefault_enable();
 100}
 101EXPORT_SYMBOL(__kunmap_atomic);
 102
 103struct page *kmap_atomic_to_page(void *ptr)
 104{
 105        unsigned long idx, vaddr = (unsigned long)ptr;
 106        pte_t *pte;
 107
 108        if (vaddr < FIXADDR_START)
 109                return virt_to_page(ptr);
 110
 111        idx = virt_to_fix(vaddr);
 112        pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 113        return pte_page(*pte);
 114}
 115EXPORT_SYMBOL(kmap_atomic_to_page);
 116
 117void __init set_highmem_pages_init(void)
 118{
 119        struct zone *zone;
 120        int nid;
 121
 122        for_each_zone(zone) {
 123                unsigned long zone_start_pfn, zone_end_pfn;
 124
 125                if (!is_highmem(zone))
 126                        continue;
 127
 128                zone_start_pfn = zone->zone_start_pfn;
 129                zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 130
 131                nid = zone_to_nid(zone);
 132                printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 133                                zone->name, nid, zone_start_pfn, zone_end_pfn);
 134
 135                add_highpages_with_active_regions(nid, zone_start_pfn,
 136                                 zone_end_pfn);
 137        }
 138        totalram_pages += totalhigh_pages;
 139}
 140