kernel/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         pte_t pte = mk_pte(page, prot);
  36         unsigned long vaddr;
  37         int idx, type;
  38
  39         preempt_disable_nort();
  40         pagefault_disable();
  41
  42         if (!PageHighMem(page))
  43                 return page_address(page);
  44
  45         type = kmap_atomic_idx_push();
  46         idx = type + KM_TYPE_NR*smp_processor_id();
  47         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  48         BUG_ON(!pte_none(*(kmap_pte-idx)));
  49 #ifdef CONFIG_PREEMPT_RT_FULL
  50         current->kmap_pte[type] = pte;
  51 #endif
  52         set_pte(kmap_pte-idx, pte);
  53         arch_flush_lazy_mmu_mode();
  54
  55         return (void *)vaddr;
  56 }
  57 EXPORT_SYMBOL(kmap_atomic_prot);
  58
  59 void *kmap_atomic(struct page *page)
  60 {
  61         return kmap_atomic_prot(page, kmap_prot);
  62 }
  63 EXPORT_SYMBOL(kmap_atomic);
  64
  65 /*
  66  * This is the same as kmap_atomic() but can map memory that doesn't
  67  * have a struct page associated with it.
  68  */
  69 void *kmap_atomic_pfn(unsigned long pfn)
  70 {
  71         return kmap_atomic_prot_pfn(pfn, kmap_prot);
  72 }
  73 EXPORT_SYMBOL_GPL(kmap_atomic_pfn);
  74
  75 void __kunmap_atomic(void *kvaddr)
  76 {
  77         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  78
  79         if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
  80             vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
  81                 int idx, type;
  82
  83                 type = kmap_atomic_idx();
  84                 idx = type + KM_TYPE_NR * smp_processor_id();
  85
  86 #ifdef CONFIG_DEBUG_HIGHMEM
  87                 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  88 #endif
  89                 /*
  90                  * Force other mappings to Oops if they'll try to access this
  91                  * pte without first remap it.  Keeping stale mappings around
  92                  * is a bad idea also, in case the page changes cacheability
  93                  * attributes or becomes a protected page in a hypervisor.
  94                  */
  95 #ifdef CONFIG_PREEMPT_RT_FULL
  96                 current->kmap_pte[type] = __pte(0);
  97 #endif
  98                 kpte_clear_flush(kmap_pte-idx, vaddr);
  99                 kmap_atomic_idx_pop();
 100                 arch_flush_lazy_mmu_mode();
 101         }
 102 #ifdef CONFIG_DEBUG_HIGHMEM
 103         else {
 104                 BUG_ON(vaddr < PAGE_OFFSET);
 105                 BUG_ON(vaddr >= (unsigned long)high_memory);
 106         }
 107 #endif
 108
 109         pagefault_enable();
 110         preempt_enable_nort();
 111 }
 112 EXPORT_SYMBOL(__kunmap_atomic);
 113
 114 struct page *kmap_atomic_to_page(void *ptr)
 115 {
 116         unsigned long idx, vaddr = (unsigned long)ptr;
 117         pte_t *pte;
 118
 119         if (vaddr < FIXADDR_START)
 120                 return virt_to_page(ptr);
 121
 122         idx = virt_to_fix(vaddr);
 123         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 124         return pte_page(*pte);
 125 }
 126 EXPORT_SYMBOL(kmap_atomic_to_page);
 127
 128 void __init set_highmem_pages_init(void)
 129 {
 130         struct zone *zone;
 131         int nid;
 132
 133         /*
 134          * Explicitly reset zone->managed_pages because set_highmem_pages_init()
 135          * is invoked before free_all_bootmem()
 136          */
 137         reset_all_zones_managed_pages();
 138         for_each_zone(zone) {
 139                 unsigned long zone_start_pfn, zone_end_pfn;
 140
 141                 if (!is_highmem(zone))
 142                         continue;
 143
 144                 zone_start_pfn = zone->zone_start_pfn;
 145                 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 146
 147                 nid = zone_to_nid(zone);
 148                 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 149                                 zone->name, nid, zone_start_pfn, zone_end_pfn);
 150
 151                 add_highpages_with_active_regions(nid, zone_start_pfn,
 152                                  zone_end_pfn);
 153         }
 154 }