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
  48         return (void *)vaddr;
  49 }
  50
  51 void *kmap_atomic(struct page *page, enum km_type type)
  52 {
  53         return kmap_atomic_prot(page, type, kmap_prot);
  54 }
  55
  56 void 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  */
  83 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  84 {
  85         return kmap_atomic_prot_pfn(pfn, type, kmap_prot);
  86 }
  87 EXPORT_SYMBOL_GPL(kmap_atomic_pfn); /* temporarily in use by i915 GEM until vmap */
  88
  89 struct 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
 102 EXPORT_SYMBOL(kmap);
 103 EXPORT_SYMBOL(kunmap);
 104 EXPORT_SYMBOL(kmap_atomic);
 105 EXPORT_SYMBOL(kunmap_atomic);
 106 EXPORT_SYMBOL(kmap_atomic_prot);
 107
 108 void __init set_highmem_pages_init(void)
 109 {
 110         struct zone *zone;
 111         int nid;
 112
 113         for_each_zone(zone) {
 114                 unsigned long zone_start_pfn, zone_end_pfn;
 115
 116                 if (!is_highmem(zone))
 117                         continue;
 118
 119                 zone_start_pfn = zone->zone_start_pfn;
 120                 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 121
 122                 nid = zone_to_nid(zone);
 123                 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 124                                 zone->name, nid, zone_start_pfn, zone_end_pfn);
 125
 126                 add_highpages_with_active_regions(nid, zone_start_pfn,
 127                                  zone_end_pfn);
 128         }
 129         totalram_pages += totalhigh_pages;
 130 }