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         inc_preempt_count();
  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                 dec_preempt_count();
  66                 preempt_check_resched();
  67                 return;
  68         }
  69
  70         if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
  71                 BUG();
  72
  73         /*
  74          * force other mappings to Oops if they'll try to access
  75          * this pte without first remap it
  76          */
  77         pte_clear(&init_mm, vaddr, kmap_pte-idx);
  78         local_flush_tlb_one(vaddr);
  79 #endif
  80
  81         dec_preempt_count();
  82         preempt_check_resched();
  83 }
  84
  85 #ifndef CONFIG_LIMITED_DMA
  86 /*
  87  * This is the same as kmap_atomic() but can map memory that doesn't
  88  * have a struct page associated with it.
  89  */
  90 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  91 {
  92         enum fixed_addresses idx;
  93         unsigned long vaddr;
  94
  95         inc_preempt_count();
  96
  97         idx = type + KM_TYPE_NR*smp_processor_id();
  98         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  99         set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
 100         flush_tlb_one(vaddr);
 101
 102         return (void*) vaddr;
 103 }
 104 #endif /* CONFIG_LIMITED_DMA */
 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
 119 EXPORT_SYMBOL(__kmap);
 120 EXPORT_SYMBOL(__kunmap);
 121 EXPORT_SYMBOL(__kmap_atomic);
 122 EXPORT_SYMBOL(__kunmap_atomic);
 123 EXPORT_SYMBOL(__kmap_atomic_to_page);