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 EXPORT_SYMBOL(kmap);
  13
  14 void kunmap(struct page *page)
  15 {
  16         if (in_interrupt())
  17                 BUG();
  18         if (!PageHighMem(page))
  19                 return;
  20         kunmap_high(page);
  21 }
  22 EXPORT_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  */
  32 void *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 }
  51 EXPORT_SYMBOL(kmap_atomic_prot);
  52
  53 void *__kmap_atomic(struct page *page)
  54 {
  55         return kmap_atomic_prot(page, kmap_prot);
  56 }
  57 EXPORT_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  */
  63 void *kmap_atomic_pfn(unsigned long pfn)
  64 {
  65         return kmap_atomic_prot_pfn(pfn, kmap_prot);
  66 }
  67 EXPORT_SYMBOL_GPL(kmap_atomic_pfn);
  68
  69 void __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_pop();
  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         }
  91 #ifdef CONFIG_DEBUG_HIGHMEM
  92         else {
  93                 BUG_ON(vaddr < PAGE_OFFSET);
  94                 BUG_ON(vaddr >= (unsigned long)high_memory);
  95         }
  96 #endif
  97
  98         pagefault_enable();
  99 }
 100 EXPORT_SYMBOL(__kunmap_atomic);
 101
 102 struct page *kmap_atomic_to_page(void *ptr)
 103 {
 104         unsigned long idx, vaddr = (unsigned long)ptr;
 105         pte_t *pte;
 106
 107         if (vaddr < FIXADDR_START)
 108                 return virt_to_page(ptr);
 109
 110         idx = virt_to_fix(vaddr);
 111         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 112         return pte_page(*pte);
 113 }
 114 EXPORT_SYMBOL(kmap_atomic_to_page);
 115
 116 void __init set_highmem_pages_init(void)
 117 {
 118         struct zone *zone;
 119         int nid;
 120
 121         for_each_zone(zone) {
 122                 unsigned long zone_start_pfn, zone_end_pfn;
 123
 124                 if (!is_highmem(zone))
 125                         continue;
 126
 127                 zone_start_pfn = zone->zone_start_pfn;
 128                 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 129
 130                 nid = zone_to_nid(zone);
 131                 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 132                                 zone->name, nid, zone_start_pfn, zone_end_pfn);
 133
 134                 add_highpages_with_active_regions(nid, zone_start_pfn,
 135                                  zone_end_pfn);
 136         }
 137         totalram_pages += totalhigh_pages;
 138 }