arch/mips/mm/highmem.c

   1 #include <linux/module.h>
   2 #include <linux/highmem.h>
   3 #include <linux/sched.h>
   4 #include <linux/smp.h>
   5 #include <asm/fixmap.h>
   6 #include <asm/tlbflush.h>
   7
   8 static pte_t *kmap_pte;
   9
  10 unsigned long highstart_pfn, highend_pfn;
  11
  12 void *kmap(struct page *page)
  13 {
  14         void *addr;
  15
  16         might_sleep();
  17         if (!PageHighMem(page))
  18                 return page_address(page);
  19         addr = kmap_high(page);
  20         flush_tlb_one((unsigned long)addr);
  21
  22         return addr;
  23 }
  24 EXPORT_SYMBOL(kmap);
  25
  26 void kunmap(struct page *page)
  27 {
  28         BUG_ON(in_interrupt());
  29         if (!PageHighMem(page))
  30                 return;
  31         kunmap_high(page);
  32 }
  33 EXPORT_SYMBOL(kunmap);
  34
  35 /*
  36  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  37  * no global lock is needed and because the kmap code must perform a global TLB
  38  * invalidation when the kmap pool wraps.
  39  *
  40  * However when holding an atomic kmap is is not legal to sleep, so atomic
  41  * kmaps are appropriate for short, tight code paths only.
  42  */
  43
  44 void *kmap_atomic(struct page *page)
  45 {
  46         unsigned long vaddr;
  47         int idx, type;
  48
  49         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  50         pagefault_disable();
  51         if (!PageHighMem(page))
  52                 return page_address(page);
  53
  54         type = kmap_atomic_idx_push();
  55         idx = type + KM_TYPE_NR*smp_processor_id();
  56         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  57 #ifdef CONFIG_DEBUG_HIGHMEM
  58         BUG_ON(!pte_none(*(kmap_pte - idx)));
  59 #endif
  60         set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
  61         local_flush_tlb_one((unsigned long)vaddr);
  62
  63         return (void*) vaddr;
  64 }
  65 EXPORT_SYMBOL(kmap_atomic);
  66
  67 void __kunmap_atomic(void *kvaddr)
  68 {
  69         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  70         int type;
  71
  72         if (vaddr < FIXADDR_START) { // FIXME
  73                 pagefault_enable();
  74                 return;
  75         }
  76
  77         type = kmap_atomic_idx();
  78 #ifdef CONFIG_DEBUG_HIGHMEM
  79         {
  80                 int idx = type + KM_TYPE_NR * smp_processor_id();
  81
  82                 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  83
  84                 /*
  85                  * force other mappings to Oops if they'll try to access
  86                  * this pte without first remap it
  87                  */
  88                 pte_clear(&init_mm, vaddr, kmap_pte-idx);
  89                 local_flush_tlb_one(vaddr);
  90         }
  91 #endif
  92         kmap_atomic_idx_pop();
  93         pagefault_enable();
  94 }
  95 EXPORT_SYMBOL(__kunmap_atomic);
  96
  97 /*
  98  * This is the same as kmap_atomic() but can map memory that doesn't
  99  * have a struct page associated with it.
 100  */
 101 void *kmap_atomic_pfn(unsigned long pfn)
 102 {
 103         unsigned long vaddr;
 104         int idx, type;
 105
 106         pagefault_disable();
 107
 108         type = kmap_atomic_idx_push();
 109         idx = type + KM_TYPE_NR*smp_processor_id();
 110         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 111         set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
 112         flush_tlb_one(vaddr);
 113
 114         return (void*) vaddr;
 115 }
 116
 117 struct page *kmap_atomic_to_page(void *ptr)
 118 {
 119         unsigned long idx, vaddr = (unsigned long)ptr;
 120         pte_t *pte;
 121
 122         if (vaddr < FIXADDR_START)
 123                 return virt_to_page(ptr);
 124
 125         idx = virt_to_fix(vaddr);
 126         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 127         return pte_page(*pte);
 128 }
 129
 130 void __init kmap_init(void)
 131 {
 132         unsigned long kmap_vstart;
 133
 134         /* cache the first kmap pte */
 135         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
 136         kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
 137 }