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         arch_flush_lazy_mmu_mode();
  49
  50         return (void *)vaddr;
  51 }
  52 EXPORT_SYMBOL(kmap_atomic_prot);
  53
  54 void *kmap_atomic(struct page *page)
  55 {
  56         return kmap_atomic_prot(page, kmap_prot);
  57 }
  58 EXPORT_SYMBOL(kmap_atomic);
  59
  60 /*
  61  * This is the same as kmap_atomic() but can map memory that doesn't
  62  * have a struct page associated with it.
  63  */
  64 void *kmap_atomic_pfn(unsigned long pfn)
  65 {
  66         return kmap_atomic_prot_pfn(pfn, kmap_prot);
  67 }
  68 EXPORT_SYMBOL_GPL(kmap_atomic_pfn);
  69
  70 void __kunmap_atomic(void *kvaddr)
  71 {
  72         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  73
  74         if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
  75             vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
  76                 int idx, type;
  77
  78                 type = kmap_atomic_idx();
  79                 idx = type + KM_TYPE_NR * smp_processor_id();
  80
  81 #ifdef CONFIG_DEBUG_HIGHMEM
  82                 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  83 #endif
  84                 /*
  85                  * Force other mappings to Oops if they'll try to access this
  86                  * pte without first remap it.  Keeping stale mappings around
  87                  * is a bad idea also, in case the page changes cacheability
  88                  * attributes or becomes a protected page in a hypervisor.
  89                  */
  90                 kpte_clear_flush(kmap_pte-idx, vaddr);
  91                 kmap_atomic_idx_pop();
  92                 arch_flush_lazy_mmu_mode();
  93         }
  94 #ifdef CONFIG_DEBUG_HIGHMEM
  95         else {
  96                 BUG_ON(vaddr < PAGE_OFFSET);
  97                 BUG_ON(vaddr >= (unsigned long)high_memory);
  98         }
  99 #endif
 100
 101         pagefault_enable();
 102 }
 103 EXPORT_SYMBOL(__kunmap_atomic);
 104
 105 struct page *kmap_atomic_to_page(void *ptr)
 106 {
 107         unsigned long idx, vaddr = (unsigned long)ptr;
 108         pte_t *pte;
 109
 110         if (vaddr < FIXADDR_START)
 111                 return virt_to_page(ptr);
 112
 113         idx = virt_to_fix(vaddr);
 114         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 115         return pte_page(*pte);
 116 }
 117 EXPORT_SYMBOL(kmap_atomic_to_page);
 118
 119 void __init set_highmem_pages_init(void)
 120 {
 121         struct zone *zone;
 122         int nid;
 123
 124         for_each_zone(zone) {
 125                 unsigned long zone_start_pfn, zone_end_pfn;
 126
 127                 if (!is_highmem(zone))
 128                         continue;
 129
 130                 zone_start_pfn = zone->zone_start_pfn;
 131                 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 132
 133                 nid = zone_to_nid(zone);
 134                 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 135                                 zone->name, nid, zone_start_pfn, zone_end_pfn);
 136
 137                 add_highpages_with_active_regions(nid, zone_start_pfn,
 138                                  zone_end_pfn);
 139         }
 140 }