arch/i386/mm/highmem-xen.c

   1 #include <linux/highmem.h>
   2 #include <linux/module.h>
   3
   4 void *kmap(struct page *page)
   5 {
   6         might_sleep();
   7         if (!PageHighMem(page))
   8                 return page_address(page);
   9         return kmap_high(page);
  10 }
  11
  12 void kunmap(struct page *page)
  13 {
  14         if (in_interrupt())
  15                 BUG();
  16         if (!PageHighMem(page))
  17                 return;
  18         kunmap_high(page);
  19 }
  20
  21 /*
  22  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  23  * no global lock is needed and because the kmap code must perform a global TLB
  24  * invalidation when the kmap pool wraps.
  25  *
  26  * However when holding an atomic kmap is is not legal to sleep, so atomic
  27  * kmaps are appropriate for short, tight code paths only.
  28  */
  29 static void *__kmap_atomic(struct page *page, enum km_type type, pgprot_t prot)
  30 {
  31         enum fixed_addresses idx;
  32         unsigned long vaddr;
  33
  34         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  35         pagefault_disable();
  36         if (!PageHighMem(page))
  37                 return page_address(page);
  38
  39         idx = type + KM_TYPE_NR*smp_processor_id();
  40         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  41         if (!pte_none(*(kmap_pte-idx)))
  42                 BUG();
  43         set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
  44
  45         return (void*) vaddr;
  46 }
  47
  48 void *kmap_atomic(struct page *page, enum km_type type)
  49 {
  50         return __kmap_atomic(page, type, kmap_prot);
  51 }
  52
  53 /* Same as kmap_atomic but with PAGE_KERNEL_RO page protection. */
  54 void *kmap_atomic_pte(struct page *page, enum km_type type)
  55 {
  56         return __kmap_atomic(page, type, PAGE_KERNEL_RO);
  57 }
  58
  59 void kunmap_atomic(void *kvaddr, enum km_type type)
  60 {
  61         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  62         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  63
  64         /*
  65          * Force other mappings to Oops if they'll try to access this pte
  66          * without first remap it.  Keeping stale mappings around is a bad idea
  67          * also, in case the page changes cacheability attributes or becomes
  68          * a protected page in a hypervisor.
  69          */
  70         if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx)) {
  71                 kpte_clear_flush(kmap_pte-idx, vaddr);
  72                 __flush_tlb_one(vaddr);
  73         } else {
  74 #ifdef CONFIG_DEBUG_HIGHMEM
  75                 BUG_ON(vaddr < PAGE_OFFSET);
  76                 BUG_ON(vaddr >= (unsigned long)high_memory);
  77 #endif
  78         }
  79
  80         pagefault_enable();
  81 }
  82
  83 /* This is the same as kmap_atomic() but can map memory that doesn't
  84  * have a struct page associated with it.
  85  */
  86 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  87 {
  88         enum fixed_addresses idx;
  89         unsigned long vaddr;
  90
  91         pagefault_disable();
  92
  93         idx = type + KM_TYPE_NR*smp_processor_id();
  94         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  95         set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
  96
  97         return (void*) vaddr;
  98 }
  99
 100 struct page *kmap_atomic_to_page(void *ptr)
 101 {
 102         unsigned long idx, vaddr = (unsigned long)ptr;
 103         pte_t *pte;
 104
 105         if (vaddr < FIXADDR_START)
 106                 return virt_to_page(ptr);
 107
 108         idx = virt_to_fix(vaddr);
 109         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 110         return pte_page(*pte);
 111 }
 112
 113 EXPORT_SYMBOL(kmap);
 114 EXPORT_SYMBOL(kunmap);
 115 EXPORT_SYMBOL(kmap_atomic);
 116 EXPORT_SYMBOL(kunmap_atomic);
 117 EXPORT_SYMBOL(kmap_atomic_to_page);