arch/mips/mm/highmem.c

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