arch/mips/mm/highmem.c

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