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