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 #include <linux/bootmem.h>
   5
   6 void *kmap(struct page *page)
   7 {
   8         might_sleep();
   9         if (!PageHighMem(page))
  10                 return page_address(page);
  11         return kmap_high(page);
  12 }
  13 EXPORT_SYMBOL(kmap);
  14
  15 void kunmap(struct page *page)
  16 {
  17         if (in_interrupt())
  18                 BUG();
  19         if (!PageHighMem(page))
  20                 return;
  21         kunmap_high(page);
  22 }
  23 EXPORT_SYMBOL(kunmap);
  24
  25 /*
  26  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  27  * no global lock is needed and because the kmap code must perform a global TLB
  28  * invalidation when the kmap pool wraps.
  29  *
  30  * However when holding an atomic kmap it is not legal to sleep, so atomic
  31  * kmaps are appropriate for short, tight code paths only.
  32  */
  33 void *kmap_atomic_prot(struct page *page, pgprot_t prot)
  34 {
  35         unsigned long vaddr;
  36         int idx, type;
  37
  38         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  39         pagefault_disable();
  40
  41         if (!PageHighMem(page))
  42                 return page_address(page);
  43
  44         type = kmap_atomic_idx_push();
  45         idx = type + KM_TYPE_NR*smp_processor_id();
  46         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  47         BUG_ON(!pte_none(*(kmap_pte-idx)));
  48         set_pte(kmap_pte-idx, mk_pte(page, prot));
  49         arch_flush_lazy_mmu_mode();
  50
  51         return (void *)vaddr;
  52 }
  53 EXPORT_SYMBOL(kmap_atomic_prot);
  54
  55 void *kmap_atomic(struct page *page)
  56 {
  57         return kmap_atomic_prot(page, kmap_prot);
  58 }
  59 EXPORT_SYMBOL(kmap_atomic);
  60
  61 /*
  62  * This is the same as kmap_atomic() but can map memory that doesn't
  63  * have a struct page associated with it.
  64  */
  65 void *kmap_atomic_pfn(unsigned long pfn)
  66 {
  67         return kmap_atomic_prot_pfn(pfn, kmap_prot);
  68 }
  69 EXPORT_SYMBOL_GPL(kmap_atomic_pfn);
  70
  71 void __kunmap_atomic(void *kvaddr)
  72 {
  73         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  74
  75         if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
  76             vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
  77                 int idx, type;
  78
  79                 type = kmap_atomic_idx();
  80                 idx = type + KM_TYPE_NR * smp_processor_id();
  81
  82 #ifdef CONFIG_DEBUG_HIGHMEM
  83                 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  84 #endif
  85                 /*
  86                  * Force other mappings to Oops if they'll try to access this
  87                  * pte without first remap it.  Keeping stale mappings around
  88                  * is a bad idea also, in case the page changes cacheability
  89                  * attributes or becomes a protected page in a hypervisor.
  90                  */
  91                 kpte_clear_flush(kmap_pte-idx, vaddr);
  92                 kmap_atomic_idx_pop();
  93                 arch_flush_lazy_mmu_mode();
  94         }
  95 #ifdef CONFIG_DEBUG_HIGHMEM
  96         else {
  97                 BUG_ON(vaddr < PAGE_OFFSET);
  98                 BUG_ON(vaddr >= (unsigned long)high_memory);
  99         }
 100 #endif
 101
 102         pagefault_enable();
 103 }
 104 EXPORT_SYMBOL(__kunmap_atomic);
 105
 106 struct page *kmap_atomic_to_page(void *ptr)
 107 {
 108         unsigned long idx, vaddr = (unsigned long)ptr;
 109         pte_t *pte;
 110
 111         if (vaddr < FIXADDR_START)
 112                 return virt_to_page(ptr);
 113
 114         idx = virt_to_fix(vaddr);
 115         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 116         return pte_page(*pte);
 117 }
 118 EXPORT_SYMBOL(kmap_atomic_to_page);
 119
 120 void __init set_highmem_pages_init(void)
 121 {
 122         struct zone *zone;
 123         int nid;
 124
 125         /*
 126          * Explicitly reset zone->managed_pages because set_highmem_pages_init()
 127          * is invoked before free_all_bootmem()
 128          */
 129         reset_all_zones_managed_pages();
 130         for_each_zone(zone) {
 131                 unsigned long zone_start_pfn, zone_end_pfn;
 132
 133                 if (!is_highmem(zone))
 134                         continue;
 135
 136                 zone_start_pfn = zone->zone_start_pfn;
 137                 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 138
 139                 nid = zone_to_nid(zone);
 140                 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 141                                 zone->name, nid, zone_start_pfn, zone_end_pfn);
 142
 143                 add_highpages_with_active_regions(nid, zone_start_pfn,
 144                                  zone_end_pfn);
 145         }
 146 }