arch/mips/mm/highmem.c

   1 #include <linux/module.h>
   2 #include <linux/highmem.h>
   3 #include <asm/fixmap.h>
   4 #include <asm/tlbflush.h>
   5
   6 static pte_t *kmap_pte;
   7
   8 unsigned long highstart_pfn, highend_pfn;
   9
  10 void *__kmap(struct page *page)
  11 {
  12         void *addr;
  13
  14         might_sleep();
  15         if (!PageHighMem(page))
  16                 return page_address(page);
  17         addr = kmap_high(page);
  18         flush_tlb_one((unsigned long)addr);
  19
  20         return addr;
  21 }
  22 EXPORT_SYMBOL(__kmap);
  23
  24 void __kunmap(struct page *page)
  25 {
  26         BUG_ON(in_interrupt());
  27         if (!PageHighMem(page))
  28                 return;
  29         kunmap_high(page);
  30 }
  31 EXPORT_SYMBOL(__kunmap);
  32
  33 /*
  34  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  35  * no global lock is needed and because the kmap code must perform a global TLB
  36  * invalidation when the kmap pool wraps.
  37  *
  38  * However when holding an atomic kmap is is not legal to sleep, so atomic
  39  * kmaps are appropriate for short, tight code paths only.
  40  */
  41
  42 void *__kmap_atomic(struct page *page, enum km_type type)
  43 {
  44         enum fixed_addresses idx;
  45         unsigned long vaddr;
  46
  47         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  48         pagefault_disable();
  49         if (!PageHighMem(page))
  50                 return page_address(page);
  51
  52         debug_kmap_atomic(type);
  53         idx = type + KM_TYPE_NR*smp_processor_id();
  54         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  55 #ifdef CONFIG_DEBUG_HIGHMEM
  56         BUG_ON(!pte_none(*(kmap_pte - idx)));
  57 #endif
  58         set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
  59         local_flush_tlb_one((unsigned long)vaddr);
  60
  61         return (void*) vaddr;
  62 }
  63 EXPORT_SYMBOL(__kmap_atomic);
  64
  65 void __kunmap_atomic(void *kvaddr, enum km_type type)
  66 {
  67 #ifdef CONFIG_DEBUG_HIGHMEM
  68         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  69         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  70
  71         if (vaddr < FIXADDR_START) { // FIXME
  72                 pagefault_enable();
  73                 return;
  74         }
  75
  76         BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  77
  78         /*
  79          * force other mappings to Oops if they'll try to access
  80          * this pte without first remap it
  81          */
  82         pte_clear(&init_mm, vaddr, kmap_pte-idx);
  83         local_flush_tlb_one(vaddr);
  84 #endif
  85
  86         pagefault_enable();
  87 }
  88 EXPORT_SYMBOL(__kunmap_atomic);
  89
  90 /*
  91  * This is the same as kmap_atomic() but can map memory that doesn't
  92  * have a struct page associated with it.
  93  */
  94 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  95 {
  96         enum fixed_addresses idx;
  97         unsigned long vaddr;
  98
  99         pagefault_disable();
 100
 101         debug_kmap_atomic(type);
 102         idx = type + KM_TYPE_NR*smp_processor_id();
 103         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 104         set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
 105         flush_tlb_one(vaddr);
 106
 107         return (void*) vaddr;
 108 }
 109
 110 struct page *__kmap_atomic_to_page(void *ptr)
 111 {
 112         unsigned long idx, vaddr = (unsigned long)ptr;
 113         pte_t *pte;
 114
 115         if (vaddr < FIXADDR_START)
 116                 return virt_to_page(ptr);
 117
 118         idx = virt_to_fix(vaddr);
 119         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 120         return pte_page(*pte);
 121 }
 122
 123 void __init kmap_init(void)
 124 {
 125         unsigned long kmap_vstart;
 126
 127         /* cache the first kmap pte */
 128         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
 129         kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
 130 }