arch/x86/mm/highmem_32.c

   1 #include <linux/highmem.h>
   2 #include <linux/module.h>
   3 #include <linux/swap.h> /* for totalram_pages */
   4
   5 void *kmap(struct page *page)
   6 {
   7         might_sleep();
   8         if (!PageHighMem(page))
   9                 return page_address(page);
  10         return kmap_high(page);
  11 }
  12
  13 void 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 is is not legal to sleep, so atomic
  28  * kmaps are appropriate for short, tight code paths only.
  29  */
  30 void *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         arch_flush_lazy_mmu_mode();
  48
  49         return (void *)vaddr;
  50 }
  51
  52 void *kmap_atomic(struct page *page, enum km_type type)
  53 {
  54         return kmap_atomic_prot(page, type, kmap_prot);
  55 }
  56
  57 void kunmap_atomic(void *kvaddr, enum km_type type)
  58 {
  59         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  60         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  61
  62         /*
  63          * Force other mappings to Oops if they'll try to access this pte
  64          * without first remap it.  Keeping stale mappings around is a bad idea
  65          * also, in case the page changes cacheability attributes or becomes
  66          * a protected page in a hypervisor.
  67          */
  68         if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
  69                 kpte_clear_flush(kmap_pte-idx, vaddr);
  70         else {
  71 #ifdef CONFIG_DEBUG_HIGHMEM
  72                 BUG_ON(vaddr < PAGE_OFFSET);
  73                 BUG_ON(vaddr >= (unsigned long)high_memory);
  74 #endif
  75         }
  76
  77         arch_flush_lazy_mmu_mode();
  78         pagefault_enable();
  79 }
  80
  81 /*
  82  * This is the same as kmap_atomic() but can map memory that doesn't
  83  * have a struct page associated with it.
  84  */
  85 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  86 {
  87         return kmap_atomic_prot_pfn(pfn, type, kmap_prot);
  88 }
  89 EXPORT_SYMBOL_GPL(kmap_atomic_pfn); /* temporarily in use by i915 GEM until vmap */
  90
  91 struct page *kmap_atomic_to_page(void *ptr)
  92 {
  93         unsigned long idx, vaddr = (unsigned long)ptr;
  94         pte_t *pte;
  95
  96         if (vaddr < FIXADDR_START)
  97                 return virt_to_page(ptr);
  98
  99         idx = virt_to_fix(vaddr);
 100         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 101         return pte_page(*pte);
 102 }
 103
 104 EXPORT_SYMBOL(kmap);
 105 EXPORT_SYMBOL(kunmap);
 106 EXPORT_SYMBOL(kmap_atomic);
 107 EXPORT_SYMBOL(kunmap_atomic);
 108
 109 void __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 }